TurboPulse

Design Complex, HAL Bengaluru

TURBO PULSE November 2022 Issue No. 07 Dear Readers, We the editorial team, feel privileged to be part of the re-launched newsletter of AERDC the “Turbopulse”. We are happy to publish this special revival edition, though after a gap but with same zest and vigor. The team is in high spirits to present \"Turbopulse\" in its all new E-version with this re-launched edition. Front Cover: GTEG-60 “TurboPulse” the rythym of team AERDC will be a quarterly AI-20 Turboprop Engine published newsletter, covering on technical articles, case studies, An-32 Military Transport Aircraft information on developmental activities of in-house engines & test beds, book reviews and individual achievements & awards. (Photo Courtesy: Money Control ) We would like to thank the contributors for this newsletter, C. A. Neeralagi without their efforts this special edition would not have been possible. We would hereby like to thank our GM & CD for their HOD(Design) encouragement & support to this newsletter publication. My special thanks goes to the editorial team for extending their time H. Shivaprakash and suggestions. It is indeed their effort and commitment which made it possible to publish this newsletter as planned. DGM(Design-AW) With these words, I and editorial team wish you all a pleasant A. Padmavathi read and wish to better the publication with your valuable suggestions and comments. DGM(D-AW) Together we can…. Empower, Lead and Impact. Voolla Nagaraju C. A. Neeralagi CM(HR) Editor-in-Chief Ashutosh Panda Write to us at: [email protected] CM(D-EDD) Published by GM, AERDC for internal circulation only Prateek Mehrotra CM(D-ATH) G. Ramesha CM(D-ENS) M. R. Mithun Kumar DM(IC)

Dear Readers, “Increasing the visibility of any organization can only be realized with a good communication.” It is with immense pleasure and absolute humility we celebrate with you the re-launching of “Turbopulse” an E-Newsletter as the voice of Team AERDC. With this special revival issue, on behalf of the Team AERDC, I would like to extend a very warm welcome to the readership of this newsletter. I am confident that this newsletter would inform all readers on the initiatives that are underway to create a stronger and more competent gas turbine legacy. Over the recent years, all reforms in AERDC have been thoughtfully planned to forge a synthesis of 4Cs Critical thinking, Communication, Collaboration and Creativity in all our design practices enabling our team to meet the dynamics of a global design environment. In this contemporary world where cut throat competition has become a part and parcel of life, it is of supreme importance that we enhance the continuous learning culture to sustain in the realms of this challenging labyrinth. Finally, I express my sincere appreciation to the editorial team who has spent a great deal of effort and time to dig deeper into the immense intellectual wealth of the AERDC fraternity and brings you the best. “Knowledge will forever govern ignorance. And people who mean to be their own Governors, must arm themselves with the power which knowledge gives. So Keep reading and keep sharing your thoughts. …Happy Reading to all ! Ramesh K General Manager, AERDC

Dear Readers, First of all, congratulations to the revival launch of Turbopulse in E-version and welcome all the esteemed readers to this special issue. Indeed, it is a real delight to address you with these few words on this special occasion which is worth honoring. This issue includes a collection of some notable articles that covers a diversity of topics in the area of engine design and technology development. I hope you will find them informative and educative. Turbopulse provides an ideal forum for information in various segments of gas turbine field in the form of research papers, survey papers, progress reports on promising developments, case studies and up-coming technological breakthroughs. With the fast-paced changes in the global market today, organizations are continuously challenged and searching for ways to increase revenues by securing access to cutting-edge technology and constantly innovating the way they do business. Therefore, Knowledge sharing and communication are to be aligned and geared to meet these remarkable challenges. I am glad to offer high appreciation to the editorial team for their commendable effort put forth for the grand revival of this newsletter and hope Turbopulse will be more informative in the future. The need of the hour is to collaborate, innovate and keep growing in order to keep pace with the changes that are inevitable.” So Keep reading and keep sharing your thoughts !!! Girish K Degaonkar Chief Designer, AERDC

November 2022 Issue No.07  GTEG-60 Success Story 06  Air Starter (ATS) Unit for Jaguar Aircraft 12  Indigenous Development of Aero Gas Turbine Engines 14 – A Rotor Dynamics Perspective 22  5-Axis Machining of Impeller at AERDC 24  Electron Beam Physical Vapour Deposition Coatings 27 for Gas Turbines  Indigenisation of Turbine Rotors of Mirage 2000 29 Starter: A Step Towards ‘Atmanirbhar Bharat’ 33  Multi Purpose Rotordynamics Test Rig – An Accom- 37 plishment of AERDC  A Comprehensive Approach —To Investigate Turbine 39 42 Blade Damage Due to Over Temperature 43  Engine Test Bed & Module Change Workshop for 44 46 Adour Mk811 of Jaguar Aircraft 48  Major Achievements - Quarter – II (2022-23) 50  Another Patent to AERDC 51 52  Paper Presented 54  See Yourself in Cyber: Together we make it Safer  MvÀÄÛPÀ¢AzÀ GvÀÄÛAUÀzÀªÀgÉUÉ  UÀUÀ£ÀZÀÄQÌ d®¥ÁvÀ  Book Review  Academic Achievements  Inspired but inspirational Enfielders: The Royals of Engines  TurboCrossword

H. Shivaprakash Deputy General Manager (Design-AW) Gas Turbine Electrical Generator (GTEG-60) APU is designed developed and certified by AERDC to meet the specific requirements of AN-32 main engines AI-20D starting, as well as standby power supply. RMSO was received for design, development, and certification of GTEG-60 APU with supply of two prototype units for Ground integration and flight trials in Feb 2013. The GTEG-60 is a turbo shaft engine, mainly consists of single stage centrifugal compressor; reverse flow annular combustion chamber, two stage axial turbine and reduction gear box to provide drive for LRU’s such as DC generator, Blower, Oil pump and fuel pump. LEADING PARTICULARS (ISA-SLS) Rated Power 110 kW Salient Features: Pressure Ratio 3.63  Single Stage Centrifugal Compressor  Reverse Flow Annular Combustor Electric Power 18 kW / 60 kW  Two Stage Axial Flow Gas Generator Turbine  Fuel Pump, Oil Pump, Starter Motor EGT < 700 deg C  Microprocessor based fuel metering unit Speed 50500 rpm Starting altitude 3.2 km Weight 135 kg (incl. generator) NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 6

GTEG-60 on AERDC Test Bed AERDC built 4 prototype units, PT1, PT2, PT3 the limited Qualification tests for GTEG-60. and PT4 . Major qualification tests such as ‘Vibration’, ‘G load’ and ‘Shock’ test have been carried PT1– Prototype engine was built in 2015 in a out as per the MIL 810 STD and specific to span of 2 years and this first unit was tested AN-32 aircraft requirements. successfully to the peak power of 80 kW in HAL, Koraput Division in Mar 2015. Further, PT2- Prototype unit has been built and tested same unit has been taken to 3BRD in Leh cold weather conditions in Mar 2016. Chandigarh and tested to start AI 20D main The APU was loaded upto 90 kW using engines on test bed in June 2015. Based on electrical load bank at ambient temperature – the satisfactory performance and clearance 5 deg C. Further, PT2 unit was used for from RCMA-E and ORDAQA-E, further units endurance testing. More than 2000 main have been built. engine starting cycles and 680 starts have been completed on AERDC Test bed. PT1 unit was further used for completing all Koraput Test Bench 3BRD Test Bed Chandigarh NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 7

Z-axis Engine Vibration Test G-Load Test X and Y axis Engine Vibration Test AERDC, GTEG team has coordinated with Directives and allotment of aircraft, BRD SLRDC for development of TGECU (Turbo Kanpur for integration and RCMA-K for Mod generator engine control unit), RCMA-E for approval and Issue of FCN and finally ORDAQA engine qualification, acceptance tests and for engine qualification tests and QA operational clearance, Air HQ for TASK coverage’s. Cold Weather Trials at Leh Hot Weather Trials at Leh Sea Level Hot Weather Trials at Jamnagar NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 8

Ist Flight of GTEG at AFS Yelahanka Task directives have been issued by Air HQ on runs have been carried out. During main 16th Nov 2017 for flight trials to evaluate the engine starting, the input voltage to the TGECU performance of Indigenous GTEG-60 on AN-32 used to drop below 16V and leads to auto aircraft. ASTE Bangalore has played a major cut-off of TGECU. The team has understood role in coordination for allotment of aircraft the requirements and designed suitable DC-DC and flight evaluation trials. converter to resolve the issue. The stake holders, DTE of Eng T(R-1) and GTEG-60 ground run on AN-32 aircraft has RCMA-K issued Mod clearance for fabrication been carried out in coordination with ORDAQA and installation of electrical looms and on 24th Oct 2018, after issuing software GTEG-60 mounting on AN-32 aircraft. change note. Main engines start trials with GTEG-60 APU were successful and PT3 & PT4 RCMA-E issued ground and flight integration units were integrated on the AN-32 aircraft clearance for PT3 prototype unit on and tested as per ASTE test schedule. All the 26-03-2018. Ground run has been carried out ground tests at Bangalore were completed and on 24th April 2018, the control law required performance parameters of the GTEG-60 few modifications to take care of engine during main engine starts were found satisfac- acceleration and deceleration during main tory. The structural integrity during low and engine starting load engaging and disengaging. high speed taxi trials were carried and found Further control law has been modified and test satisfactory. After flight sortie the engine was NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 9

Inspected and found satisfactory. Further All the observations given by ASTE during the testing at various ambient conditions were trials has been taken care by AERDC and ASTE carried out at Jamnagar (hot and cold), has submitted the flight evaluation report to Srinagar (cold), Chandigarh (cold), and Leh (hot Air HQ. and cold). The GTEG Team has ferried along A production order, RMSO was received on with AN-32 aircraft during testing and acquired 25th Aug 2022 to manufacture and supply 10 the APU load and engine health parameters at GTEG-60 units. all the air bases. IPR Certificate of Registration of Design Design No. 303306 Title of the work: Gear Box of Auxilliary Power Unit for Transport Aircraft. Certificate of Registration of copyrights Registration No. L-88906/2020 Title of the work: Acceptance Test Procedure for GTEG-60 APU Patent Certificate Patent No. 406086 Title of the work: High Efficiency Centrifugal Compressor Module for Small Gas Turbine Engine NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 10

Awards  The efforts towards different phases of development and certification of GTEG-60 have paved the path for several laurels and team was awarded with SODET Excellence award for technology development and Innovation for the year 2019-20.  Mission Raksha Gyan Shakti, recognition for the outstanding contribution towards self-reliance in defense of invention of Model of APU for Transport Aircraft and grant of Industrial Design.  In the recently conducted Defence Expo, Team GTEG-60 has bagged prestigious Raksha Mantri Award RAKSHA SRIJAN RATN for the year 2021-22 The success lies in the concerted team effort and passion to work together towards a common vision makes the Project to reach the Goal NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 11

Air Starter (ATS 37) is designed for starting the Rolls-Royce Amar Singh Deputy General Manager Adour-Mk 804E/811 engines on Jaguar aircraft through bleed air from aircraft mounted Air Producer. During main engine start-up, Kaushik Das the starter drives the aircraft engine(s) upto light-up speed and Chief Manager (Design-SD) assist during acceleration. The aircraft engine becomes self- sustained within few seconds and quill shaft gets decoupled from the starter drive through sprag clutch mechanism. Salient Design Features of HAL Air Starter  It is a drop-in replacement of existing one  It does not have any mass penalty and meets the stipulated performance parameters  Good operational capability (on ground) in extreme climatic conditions and altitudes, without special preparation  Low cost of ownership ATS Specification  Air Flow Rate (Intake) : 0.417 kg/s  Expansion Ratio : 3:1  Output Shaft Rotation Speed : 6000 RPM  Output Shaft Power : 36.8 kW  Operating Temp (on ground) : -20 to 50 C  Operating Altitude (on ground) : 3048 m (10000 ft)  Overall height : 219.75 mm  Overall width : 200 mm  Overall length : 290 mm  Weight : 6.8 kg NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 12

Applications : Adour Mk804/Mk811 : Jaguar  Engine  Host Aircraft Major Achievements  Airworthiness Certification  Productionising and supply of units to IAF  Foreign exchange savings of the tune of billions of Rupees Business Potential  Self reliance in Air Starter technology  Productionising indigenous Air Starter is beneficial both from commercial and operational point of view  Expertise gained in design, development, certification and production of air starter can be extended for various other platforms NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 13

Dr. T. H. Gonsalves Chief Manager (Design—SD) Modern Aero Gas Turbine development rotor dynamics can be detrimental to the operation and in some extreme cases may lead is an engineering challenge for its ever to grounding of the entire fleet. increasing performance, reliability and safety requirements. The design of elements of gas In this article, an insight into the fundamental turbine is an iterative interdisciplinary process requirements and the approach to be followed to meet the overall defined specification. In in the design and operation of small and addition to the above, to be relevant in a highly medium aero gas turbine engines is discussed specialized market, the advanced cutting edge from the rotor dynamics point of view. technologies have to be continuously incorporated. Hence, the aero gas turbine Background development has to pass through a series of complex engineering processes before it High vibration is one of the most commonly culminates in airworthiness certification. Rotor encountered issue by any rotating machinery. dynamics is one such important process of Often, resolving the high vibration design and operation which deals with the encountered by the rotating machine can be dynamics of rotor-bearing-support system. very tricky and consumes a lot of resources. Based on the rotor dynamic analysis, each Trouble shooting of the vibration problem element of rotor-bearing-support system is itself can be troublesome even after following designed. The main objective of rotor dynamics all the laid down manufacturing and assembly is to design a rotating machine with least procedures. There are many instances of vibration for the safe and smooth operation engines being kept lying for years in the shop during the entire life cycle. Any laxity in the due to unidentified high vibration problem. At times, high vibration can be nightmare to all the associated design, production and quality NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 14

But in some rare cases, the cause for high the 20th century, the industrial turbine vibration may be inherent in the design itself. operation was limited below the first critical Hence, a scientific and holistic approach is speed. Any attempt to operate above or in essential in dealing with rotor dynamics of aero proximity of the first critical speed encountered engines from design to the final operation. violent and uncontrolled vibrations. Similarly, many industrial turbines encountered Design and Development catastrophic failures due to rotor dynamic instability. Therefore, it was assumed that the Contrary to the common understanding that operating speeds shall be free from critical and rotor dynamics involves only the rotating instabilities. The reason for the rotor dynamic system and its supporting bearings (rotor- instability was later attributed to the rotating bearing system), rotor dynamics involves internal damping (RID) due to the bolted joints dynamics of all the elements of the rotating used for joining compressors and turbines. The machine (rotor-bearing-support system). subsequent emergence of curvic coupling joints Therefore, the designer involved in the rotor eliminated this instability problem. The modern dynamics shall have the complete knowledge gas turbine engines are now able to operate of all the elements such as rotating assemblies, above their first two rotor dynamic critical the supporting bearings, stationary casings and speeds. The application of advanced bearings, all LRU’s. Any unaccounted possible excitation flexible supports with damping using modern source can create serious rotor dynamic finite element based rotor dynamic analysis problem during the development testing or any tools has paved the way for higher operating point of time in service. Rotor dynamics is the speeds. Rotor dynamics designers can now study of dynamic behavior of rotor-bearing position the critical speeds as per their design system considering all the possible direct requirements using these state-of-the-art (including the self-excitations) and indirect technologies. Hence, solving the rotor dynamic influences of other rotating and static problems is an evolving process by continuous structural elements of the rotating machine. research, design and testing of elements of rotor-bearing support system. As the science and technology progressed over the years, understanding of rotor dynamics is  The basic rotor dynamic activities such as also evolved. The initial pioneering Jeffcott and modal analysis and support stiffness Rankine rotor dynamic models assumed a sensitivity analysis are carried out to simply supported shaft with a central rotor identify the possible resonances in the disc. Similarly, most of the early rotor dynamic operating range and the effect of bearing estimations were based on the basic structural supports in terms of bearing span, number vibration approximations. In the early years of NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 15

Figure 1 illustrates a typical rotor dynamics analysis process flow of rotor-bearing-support system. Fig-1 : Rotor dynamic analysis flow diagram stiffness values. second forward whirl mode is close to lower operating speed range.  Critical speed analysis identifies the critical speeds and the associated strain and kinetic  In the Campbell diagram, at zero speed the energies in the rotor and bearing supports. forward and backward frequencies are If the strain energy is more in the supports identical. As the speed increases, the in comparison to the rotor, the vibration gyroscopic damping of the rotors induce mode is identified as bearing/rigid mode as stiffening effect on forward whirl motion of desirable for the smooth operation. If the the rotor-bearing. As a consequence, the strain energy is more in rotors, then the forward whirl frequency increases as the mode is a bending/flexible mode which is operating speed increase. For the backward undesirable in the operating range. whirl, the gyroscopic damping induces softening effect due to which the frequency  The Campbell diagram shown in Figure 2 of vibration reduces. identifies the critical speeds with in the operating range. The gas generator  The backward whirl motion is a rotor rotor-bearing-support system of Shakti dynamic behavior which is as on today not engine with optimum damping in the form fully understood. Even though all the rotor of squeeze film damper is operating with dynamic calculations estimate the backward two forward whirl rigid bearing modes. The whirl speeds, they are mostly ignored. The NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 16

Fig-2 : Campbell diagram/mode shapes of Shakti Gas Generator Rotor-Bearing system  commonly known backward whirl where backward (BW) whirl critical speeds excitation sources are the blade-casing identified to be excited by the unbalance rubbing, bearing damage and unbalance of and resulted in failures such as the blower counter rotating dual rotor-bearing system wheel shaft shear neck failures of oil with inter shaft bearing. There are instances cooling system (OCS) shown in Figure 3. Fig-3 : OCS shaft shear neck fracture NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 17

 The long slender flexible shaft of power study by the author on similar slender shaft turbine rotor-bearing system of Shakti rotor-bearing system has revealed that engine operates with two critical speeds using the hybrid stiffer material for the close to the operating speed. Due to longer shaft can effectively overcome this bearing span of the flexible shaft, in the first problem. As shown in Figure 4 and Figure mode the rotor strain energy is more than 5, the shaft deflection can be reduced to a bearing supports. Due to the flexibility of whopping 300%. However, these the shaft relative to the bearing supports, encouraging theoretical estimates require maintaining low level of deflection is further experimental testing/investigation essential for the safe operation. A research to incorporate on any application. Fig- 4 : Campbell diagram comparison of steel and stiffer shaft Fig-5 : Unbalance response comparison of steel and hybrid material shaft NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 18

Manufacturing and Assembly unbalance is above the acceptable limit, the engine will have high first order vibration Following the production process of each and (1x). The poor assembly due to excessive run every component/system of in due diligence out, alignment, loose assembly etc., induce is of paramount importance for smooth higher orders vibration (1x, 2x, 3x..,) resulting operation of the rotating machine. Every in failure due to high vibratory stresses. deviation in the part from the drawing/ standard specification will have a direct effect Sometimes the most unexpected cause such on the rotor dynamics of the engine. A poorly as overriding of two independent structural machined rotor with high eccentricity due to components can also create very high level of manufacturing defects such as runout will vibration. The poor assembly of flame tube have high unbalance. The balancing of with fuel burners resulted overriding of rotating system shall be performed precisely burners on the swirlers as shown in Figure 6. to meet the acceptable unbalance limits. The Correcting the overriding and other related residual unbalance limits are prescribed/ improvements in structural assembly has decided based on the rotor dynamic analysis resolved the problem which was initially and type of the application. If the balancing presumed to be due to high rotor unbalance. carried out is erroneous and the residual Fig-6 : Flame tube and fuel burner assembly of GTSU/GTEG/AP NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 19

Development and Production Testing the testing. In many cases it was found that the vibration signature was not properly analyzed For any rotating machine to be safe during its and concluded improperly to create high speed operation, the use of the state-of- unnecessary operational hindrances. the art health monitoring system is very essen- tial. The vibration health monitoring system Operation shall have order analysis such as frequency spectrum, waterfall plot, bode plots and other Monitoring and analysis of rotor dynamics advanced fault diagnostics tools. Vibration (vibration) of gas turbine engine in service is measurement devices such as accelerometers, required for the safety during continuous velocity pickups and displacement probes shall operation and to establish the findings of any have proper range and accuracy levels to fit issues that may encounter in the future. into the application. The selection of Though, in-service only limited instrumentation appropriate vibration measurement unit is possible for health monitoring, the (acceleration in ‘g’, velocity in mm/sec or inch/ measurement shall cover all the basic vibration sec and displacement microns or mils) is critical information required for understanding and for the safe testing. For high speed operation resolving any problem that may encounter of GTSU/GTEG/Air Generator etc., vibration during the in-service operation. There are measurement in ‘g’ is appropriate. For low and instances where the design of rotor-bearing medium speed engines mm/sec (or inch/sec) is system was revised based on the in-service the most appropriate unit of measurement. vibration feedback. All the environmental Sometimes, displacement units in microns or conditions are practically not feasible to mils is used for large engine application which simulate in digital or experimental models operates below 10000 rpm. during development. In one such example, the vibration damper used in an aero engine widely Before testing, the first and the most important used by commercial airliners was found to be step shall be to calibrate the entire vibration in-adequate in a certain part of the world due acquisition and analysis setup. The calibration to its unique environmental conditions. The shall be carried out in intervals as specified and continuous monitoring and acquisition of shall be recorded without any ambiguities. The vibration data was helpful in timely identifying acceptable vibration levels for alarm/abort the problem. shall be very clear before starting the test. The specified vibration limits shall be strictly abided Conclusions during the testing. In case of high vibration, the issue shall be analyzed properly before taking As brought out in the introduction and in the any decision to either abort or to continue with subsequent discussions, the rotor dynamic analysis is a continuous process throughout the NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 20

modern technological innovations of any drawings. element of rotor-bearing-support system can be implemented in gas turbine engine It is also very important to remember that the application after the in-depth theoretical and measured rotor dynamic/vibration test data experimental analysis. shall be analyzed properly and otherwise can have detrimental effect on any engine The inadequacy of a certain design or a flaw development program. can be rectified only after thorough analysis and proper understanding. Though most of the Test data from all the ground/flight testing and rotor dynamic design flaws are proven to be other rotor dynamic experiments can be not suitable to the operation of the engine, utilized in model updating of rotor-bearing some can be overcome by improved systems to further improve the rotor dynamic manufacturing/assembly. Hence, it is prediction. important to understand the role of quality assurance of parts and systems in meeting the Finally, it is concluded that rotor dynamics and requirements given in relevant standards/ vibration analysis has an important role to play in the entire life cycle of aero engine from design to the final in-service operation. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 21

Shiva Kumar U Nandakumar Senior Manager (Design—ENS) Chief Manager (Mfg) AERDC has taken up the indigenization of Air producer engine for Jaguar Aircraft. The impeller is a critical component in the centrifugal compressor of the engine. The CNC unit of AERDC, with team members Mr Shivakumar. U, SM (D-ENS) for CNC programming, Mr Jaya Prakash Maharana SM (P&P) for Fixture design & Mr Nandakumar CM (Mfg) for Manufacturing, mentored by Mr Ebenezer Daniel, CM (P&P) & Mr V Reddy, DGM (D-ENS), have taken up the in-house manufacturing of the impeller. The impeller features 11 nos. of thin aluminum blades with high twist angle. The primary challenge in machining is not only the 5 axis programming for complete approach & collision avoidance, but also to calculate cutting parameters such as depth of cut, feed rate and step-over to maintain the deflection of part within the tolerance limit due to the cutting force. Fig-1 : Impeller 3D model Fig-2 : Manufactured Impeller @ AERDC NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 22

The Multi-axis CNC programming is done using roughing” and “SWARF finishing” technology. MasterCAM & Esprit CAM softwares and the With the ‘Constant chip load roughing’ method theoretical calculations were done to establish the feed rate & depth of cut was increased by 4 the cutting parameters, with the aim to reduce times than conventional machining and with blade deflection due to the cutting force. The “SWARF finishing” method, the complete side machining was carried out in 5-axis milling (flank) of the tool was used for finishing instead machine and the first prototype was of the tool-tip, which helped to finish the manufactured within 4 days of design blades in single pass of the tool. By completion. The total cycle time was 82 hours implementing both the methodology, the to machine from bar-stock to the final finished machining time is reduced from 82 hours to 10 product. hours and achieved an average accuracy of 35 microns. So far, 7 nos. of impellers have been The program was further optimized for batch manufactured in-house. production by introducing “Constant chip load NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 23

S. Esakki Muthu Deputy General Manager (Design—SM &D) The thermal barrier coatings (TBC’s) are insulating ceramic coatings deposited over bond coated supper alloys. TBC’s are used to reduce the metal temperature which consequently improves the component durability and allows for adopting higher turbine entry temperatures. The coatings are done through Plasma spray or Electron Beam Physical Vapour Deposition (EBPVD) methods. EBPVD finds vast applications in various field like gas turbines, automobile engines, microelectronics, space applications, medical implants, semiconductor industry and optical industry. EBPVD methods are used in semiconductor to form thermal and chemical barrier coatings to protect surfaces against corrosive environment. In optical industry, it is used to impart the desired reflective and transmissive properties and used to improve the wear resistance of cutting tools. Gas Turbine Applications yttria stabilised zirconia (YSZ) ZrO2 + Y2O3 has one of the lowest thermal conductivity value at EBPVD coatings are broadly used as thermal elevated temperatures, with a rank of 2.3 W/m isolators between the substrate and hot gases -K at 1000oC and low thermal expansion of in turbine engines. The TBC’s are applied to the 11x10-6 (0C)-1. The YSZ coatings are used for hot engine components like combustor, nozzle corrosion protection at high temperature as guide vanes, rotating blades, shrouds and well as thermal strike resistivity to the afterburners. The TBC system consists of Nickel components. based super alloy substrate (Base metal), a me- tallic bond coat (Ni-Co-Cr-Al-Y) and a ceramic Large strain is developed due to mismatch top coat. The ceramic top coat is 7% wt yttria between the coefficient of thermal expansion stabilised zirconia (7YSZ). (CTE) of top coat and substrate. The EBPVD TBC system has high strain tolerance due to the Thermal conduction has to be low, which re- columnar microstructure of the YSZ top coat. quires an outer layer of ceramic material. The NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 24

The Bond coat MCrAlY (M = Ni or Co) Fig-1 : EBPVD coated cooled HP Turbine blade of deposited on the substrate provides strong GP-7200 Engine mechanical bonding between the substrate and top coat. The bond coat elements are Ni-45 to 48%, Co-21-23%, Cr-19-21%, Al-12.5-13.5%, Y-0.5-0.75%. Top coat is Yttrium stabilized zirconia, ZrO2+ 7%Y2O3. The bond coat thickness of 60-100 microns and top coat thickness of 160 to 200 microns is carried out for medium gas turbine blades. The EBPVD coated cooled HP Turbine blade of GP-7200 Engine is shown in Fig-1. In the EBPVD coating facility, the blades are fixed on the rotating fixture inside the chamber. The chamber temperature is maintained with respect to coating material. Fig-2 : EBPVD coating Facility Schematic NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 25

Properties EB-PVD Plasma Spray Thermal Conductivity (W/mK) 1.5 0.8 Surface Roughness (μm) 1.0 10 Adhesive Strength (MPa) 400 20-40 Erosion rate 1 7 Microstructure Columnar Laminated The advantage of EBPVD coatings over plasma spray coatings (Ref. Fig-3) are. Fig-3 : Micro-structure of EBPVD and Plasma Sprayed TBC The coating ingots are vapourised through Electron Beam. The vapours are deposited over the blade for a period based on thickness (Ref. Fig-2) The EBPVD coatings enhance the creep-fatigue life of the turbine components. It improves the oxidation resistance at elevated temperature. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 26

Syed Mazhar Ahmed Dr. Joseph Shibu K Amar Singh Senior Manager (Design) Chief Manager (Design) Deputy General Manager (Design) Noelle-180 Jet Fuel Starting (JFS) System is designed for starting the SNECMA M53-P2 engine of Mirage-2000 aircraft without the need for external ground support services. During main engine starting, the starter drives the engine upto light-up speed and continues to assist during the acceleration phase till self-sustaining speed. The main engine becomes self-sustained in approximately 30 s. The starting system is basically a turbo shaft engine comprising two distinct sections: gas generator and starter (turbine/gearbox). The gas generator comprises the starter motor, the air intake assembly and the core engine including the Compressor Wheel, Combustor and Gas Generator Turbine Rotor (GGTR). The starter section includes Free Power Turbine Rotor (FPTR), reduction gear box and an output shaft. AERDC has taken up and completed the indigenisation of Compressor Wheel, GGTR and FPTR in pursuit of self-reliance in design and manufacturing of core critical components. This article briefly narrates the indigenization process adopted. GGTR FPTR Compressor wheel NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 27

Imported GGTR and FPTR are manufactured assembled in heated condition, the same has from Nickel-based alloys through investment been established iteratively through casting. A detailed study is carried out to experimentation. explore the possible indigenization routes for The indigenously developed compressor wheel these components. As the component has been tested at 115% and 122% overspeed requirement per year was limited, forging conditions along with 6600 cycles of spin to route was chosen for the manufacturing to demonstrate the structural integrity and life of meet the optimal cost over the entire life span the component respectively. On similar lines of the components. AERDC used indigenous the indigenously developed turbine have been Nimonic alloy forgings developed and supplied tested at 115% and 122% overspeed and 10000 by HAL F&F division. cycles of spin to demonstrate structural integrity and the life. Functional tests were also Aerothermal analysis has been carried out for carried out for 25 starts to demonstrate the the given mass flow rate, pressure and performance (speed Vs torque characteristics) temperature to generate blade profiles for in the assembled conditions. stipulated performance. 3D model of Based on the satisfactory type test inspections, components have been created and Modal & the components were provisionally cleared for stress analysis have been performed to verify production and fitment trials on NOELLE-180 the structural integrity and fatigue life. These starter, for 1000 starts through Letter of analysis corroborated the design requirements Technical Approval (LoTA). for adequate service life without any weight penalty. Subsequently, detail drawings of the Indigenization of these components has components were generated. resulted in Foreign Exchange (FE) savings of 3.05 crore till date and it is expected to accrue Compressor wheel consist of a steel inducer FE savings of 40 crore in the next 30 years of part and an aluminium impeller, assembled anticipated service. together by a spring washer and two dowels. The design of spring washer was most critical Successful development of these components as it controls the separation force experienced is another step towards Atmanirbhar Bharat in by the impeller and inducer due to the the field of Jet Fuel Starter repair, maintenance momentum of the air flow. The separation and overhaul. force was estimated through numerical analysis and the spring washer was designed. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 28 As the assembly of the impeller and inducer of compressor wheel requires the spring washer to have a certain slope and is to be heated and

Rashmi Prabha Dash Manager (Design—EDD) A ERDC is establishing state of the art Multipurpose Rotordynamics Test Facility for design validation of various engine rotor systems. A brief about the design challenges faced in arriving the best solutions for various elements of the test set up is highlighted in this article. Our division is indigenously developing a twin spool medium thrust class engine for military trainer aircrafts and has taken privileged initiative to design and develop the rotordynamics test rig for evaluating performance of rotor system. Rotor system is the most important part of the engine as it has to withstand excessive stresses at high speed levels. Rotor system being the safety critical hardware of the engine, needs design validation through experimental tests for its structural integrity. Objectives and Importance of the Rig Rotordynamics is one of the important discipline in high speed rotating machinery design, concerned with the behavior and diagnosis of rotating structures. In this discipline, every concept and new technology of rotor-bearing support system is to be analyzed and tested experimentally before implementing in the actual design. The experimental rotordynamics test needs a test rig to be performed. The multipurpose rotordynamics test rig is a versatile platform for demonstrating all the phenomenon in classical rotordynamics to know the behavior of the full rotor system, such as  Influence of unbalance force  Vibration pattern and over all vibration level  Critical speeds and impacts of misalignment  Impacts on bearings  The gyroscopic effect and alignment issues NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 29

Fig-1 : Generic representation of the Rig Fig-2 : Front Pedestal of Multi Spool Rotor Rig The test rig will cater for single and twin spool design process for few elements of the test rig rotor system. It will assist in design validation are discussed here. through testing for intended application. The test facility proposed is of generic nature Equivalent Rotor Design encompassing various rotor configurations such as simply supported, both sides over An equivalent rotor system is used for testing. hanging, one side over hanging etc. This rig can There are several limitations that restrict the accommodate different rotor dimensions, use of real engine rotors for test rig evaluation, wheel diameters, speeds and bearing spans. such as The test facility will comprise of Test Bench, Instrumented Pedestals, DC drives, Gear Boxes,  Huge power is needed to drive the real Flexible Couplings, Lubrication system, Axial engine rotor system loading system and Safety enclosure. The generic representation of the test rig is shown  Safety issues in case of blade-off condition above in Figure 1. can be avoided Detail Design Perspective  Commercial aspects The design of the test rig aims at proper Most of the other components such as clamping, positioning and assembling the rotor bearings, seals and casing depend mainly system with the rig pedestals for evaluating the on the rotor’s design. Understanding the functional and operational characteristics of complexity of the engine system, it is the rotor-bearing support systems. The basic always advisable to use rotor system simi- concepts and challenges faced during the lar to the main engine in the rotor test rig. There are some practical difficulties, which restricts the use of actual rotor as a test specimen like,  Actual rotor system demands more power while testing NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 30

 Manufacturing process is more multifaceted Moment of Inertia, Bearing Span and and time consuming (In case of equivalent Natural Frequency is similar in the rotor, manufacturing process is easier with equivalent rotor as in the actual engine. lead time due to use of common material like steel alloy) Over simplified model such as Jeffcott rotor might be an option for the test rig but to  The geometry is of simple disc type, instead of visualize the nearest behavior of the rotor the blisk type (bladed disc). The mass, Polar system under operating condition equivalent rotor is the best option. Fig-3 : Single spool Equivalent Rotor arrangement Fig-4 : Twin spool Equivalent Rotor arrangement Rotor Arrangements co-axially rotating with different speeds and are engaged via inter shaft bearing. One of the test rotors for present study is twin spool equivalent rotor system for Conducting test for twin spool equivalent medium thrust class engine application. Twin rotors demands high order workmanship and spool equivalent rotor system has similar sophistication. The objective of the test is to complexities as actual twin spool rotor study the interactions between high pressure system of engine. The reason is two shafts (HP) and low pressure(LP) rotors, connected NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 31

through intershaft bearing at design and off assembled and subsequently used on design conditions. Twin spool equivalent Rotordynamics Test Rig. rotor arrangement with bearings supports is shown in Figure 4. The state of the art design will facilitate the incorporation of following features to make it Pedestal Design more realistic The pedestal is the major load bearing part of  The best and flexible arrangement of Ped- the test rig. It facilitates the appropriate estals features for supporting, positioning, clamping and centering the rotor system. The rotors  Precision mounting of equivalent rotors in are very crucial parts and are designed with a single spool and twin spool rotor precision class. Testing of Rotor system arrangements demands equivalent precision and accuracy in the test rig pedestals. Aligning the full rotor  Establish desired misalignment in the assembly, creating misalignment, measuring equivalent Rotor system the misalignment and axial loading are some of the challenges for the test rig pedestal  Provisioning Safety aspects of the test design. equipment Proper arrangement has been ensured for  Adequate positioning of measuring misalignment and axial loading. Front Pedestal instruments is having provision for misalignment and rear pedestal contains provision for axial loading. A Conclusion load cell is proposed for force measurement and two dial indicators are positioned on In the Rotordynamics Test Rig, the equivalent either sides of the pedestals to record and rotor can be tested for operating range and maintain misalignment. Different parts of a any short fall will be emerged out in course of pedestal are shown in the Figure 2. testing. Based on the results, corrective measures can be implemented on the Best Impression hardware prior to fitment on actual engine well in advance. Rotor system can be verified The proposed design of pedestals, for bearing supports, dynamic characteristics, intermediate pedestal, alignment device and and sensitivity on unbalanced distributions, equivalent rotors will fetch the best suitable Interactions of HP (high pressure) and LP (low arrangements that can be manufactured, pressure) spools in presence of inters haft bearing, effect of axial load on ball bearing and the effect of misalignment. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 32

Ashutosh Panda Chief Manager (Design—EDD) The components of a turbine especially blades and disk are subjected to a wide variety of damaging influences, which act together in an exceptionally complex sequence. Due to the demands for high turbine inlet temperature and creep resistance, the rotor blades of modern gas turbines are produced by investment casting which allows the realization of complex inner cooling air channels. The air for the protective cooling air film is directed to the surface through many openings. The typical blade materials are nickel-based alloys in which a precipitation phase (Ni3Al) hardens these materials and ensures sufficient creep strength. These alloys can be polycrystalline, single crystal, or directionally solidified, depending on the casting process used. Alignment or avoidance of grain boundaries is done because these are special weak points for creep stress and thermal fatigue. Though ample care used to be taken during damage analysis, including the identification design stages and operational cycle formula- and assessment of root causes in a systematic tion, some unprecedented situation during way. This topic does not completely cover all exploitation causes violations in operational the damage scenarios, but rather offers an modes which lead to build up of abnormal overview approach for preliminary engine parameters that affect the engine encapsulation of severity of specific damages structure adversely. that are caused by overly high blade temperatures. Damages occur due to over It is not possible to develop a sufficiently safe temperature are primarily creep, oxidation, and and successful remedy without a reliable thermal fatigue. Fig-1 : Representative sketch of blade internal Fig-2 : Low pressure turbine blade with over- and external cooling heat mark NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 33

Over temperature in turbine blades can have sistance, such as most used Ni-based materials, then the amount, size, form and composition of very different causes? Some of them are as fol- this phase can be used to determine the thermal influences. lows: However, a puzzling factor is the fact that long Unusually high gas temperatures (compressor, subsequent periods of operation at normal and/or combustion chamber problems) temperature alter the analyzable symptoms Lack of cooling air due to changes in the blad- which is due to further hardening. Another ing (e.g. constriction of cooling air ducts due to possibility for analysis of thermal influences is a blockages or plastic deformation ) metallographic inspection of protective coatings Poor cooling air inflow (e.g. due to problems (diffusion coatings, applied thermal barrier with the compressor or with seals). coatings) for distinctive changes. Hot parts sub- Poor heat input and removal (e.g. spalling of ject to high creep loads can show so-called creep thermal barrier coatings, surface roughness, and openings in their structure or on the fractured oxidation in cooling air ducts). surface. These opening or pores provide clues Consequently, before arriving at any conclusion with respect to acting damage mechanism, direction of loads, and degree of damage. the following queries must be answered within Unlike the forged turbine blades of older generation engines, the cast alloys typically the outline of the required damage analysis: used today do not exhibit pronounced creep pore formation. The lack of creep pores does not Was there really a damage-inducing over tem- allow one to conclude that creep was the cause perature? of damage. How high was the over temperature or how How high was the over temperature? much it exceeded beyond the limit? The minimum attained temperatures can be Which parts and zones are affected? determined by structural characteristics, When exactly did the over temperature hap- pen? fracture surface features and signs of melting. What was the duration of the over tem- This assumes that these effects only occur at perature? specific temperatures. If there are pronounced Which characteristics or events can rea- sonably explain the over temperature? signs of diffusion, then the time-based influence An inquisitive approach for answering must be considered. these questions may be as follows: Which parts and part zones are affected? Was there really a damage-inducing over temperature? The geometric distribution (i.e. on the rotor or Distinctive externally noticeable signs indicate relative to the gas flow) of the overheated the occurrence of damage-causing thermal loads. Over temperatures that do not create any engine parts and their concurrently altered outwardly observable damage symptoms must also be identified. If the engine parts are made operating behavior (i.e. combustion chamber, from materials that depend on the gamma phase (hardening phase) for their creep re- cooling air supply, or compressor) can provide important clues regarding the progress and NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 34

Fig-3 : HP turbine blade with overheat damages Fig-4 : HP turbine blade with severe oxidation of the damage. Traces of hot streaks in the process. The tarnishing probably occurred at the combustion chamber are a typical indicator for very end of the damage process, possibly during over temperature. If overheating is suspected, the cooling phase. Due to the additional the combustion chamber must also be atmospheric influence, extreme care must be inspected for indications of a poor temperature taken when drawing conclusions. profile. Signs of this include deformations, cracking, fractures, and unusual coke buildup, The thickness of oxide coatings only allows a very damaged or blocked nozzles, etc. rough estimation of time, if any. One must consider that fresh fractured surfaces are very When did the over temperature occur? oxidation-friendly at first and those cracks oxidize differently than surfaces which are more Response to this question is essential not only exposed to the atmosphere. The estimation of a for the damage mechanism, but also for more damage-causing operating temperature becomes exact assessment of the part temperatures increasingly realistic with every known additional based on structural changes. Information for source of information regarding the time-based this can be found in testing protocols or data growth. documented. Records that are not directly relevant to temperatures can also be useful (i.e. Which characteristics or events can rea- parameter changes that indicate a stall/surge or sonably explain the over temperature? the vibration indicator for a discrepancy). Replying this question demands an all-inclusive What was the duration of the over tem- view of the damage process. For this reason, a perature? criterion for sufficiently accurate conclusion is that all affected components and preferably the If the time of the process, especially the creation entire engine should be made available for of the over temperature, is sufficiently limited, it analysis. No satisfactory conclusion can be can reveal the duration of the incident. expected if there is a “pre-selection” of parts or if Tarnishing can be expected only on fresh metal only visibly damaged parts are available for surfaces which were created during the damage study. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 35

Conclusion The sensible compilation of observations to the above queries sets a clear tone for subsequent failure investigation to establish the root cause for over temperature in engines. This line of attack during investigations enables the MRO team to provide vital inputs for design engineers for pursuing enhanced R&D so that they can hand over an improved & more reliable power plant in future. We can humbly say this input is a promising investment which yields rich dividend in future. How can two people fairly share a cake with a single knife cut? Ans: The first person begins by dividing the cake into two pieces. Then the second person chooses which piece they will take. This means both sides will be satisfied. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 36

MCW training at HAL, Bengaluru AERDC signed a contract with MOD for installation and commissioning of ‘Engine Test Bed & Module Change Workshop’ for Adour Mk811 of Jaguar Aircraft on turn-key basis at 33 Wing, Air Force Station located at Jamnagar. The Engine Test Bed is designed for U-type where intake and exhaust systems are vertical for minimum noise, overhanging thrust stand for access to accessories and advanced instrumentation and control system for engine testing, analysis. Design, Installation, commissioning and calibration of all systems are completed on site. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 37

AERDC Division organized an extensive training program which was conducted in two phases at En- gine Division and Air force Station Jamnagar from July 2022 to September 2022. 4 Batches of Air force personal from 7 Wg, 17 Wg and 33 Wg comprising of 15 officers/technicians each were imparted training. Each phase consisted of 6 days which included class room sessions and on-job training cover- ing all the MCW and ETB systems. The training has equipped the participants (60 Nos. approx) to inde- pendently carry out upcoming assembly, testing and maintenance related activities of Adour Mk811 ETB Training at IAF Jamnagar NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 38

Project : GTSU-127E Achievements : One more starter engine is making its way into the gas turbine starters segment of AERDC i.e. GTSU-127-E. The GE-414 engine of LCA Mk-II needs a starter of 135 kW, a 25 kW more powerful engine in comparison to the GTSU-110 which starts the GE-404 engine of LCA Mk-I aircraft. ADA, the platform designer, has entrusted AERDC for the design and development of this starter engine. The final approval for fund sanction is yet to be obtained from MoD. However, AERDC has gone ahead with development of the engine to the specification provided by ADA and has successfully built a TD unit with its internal fund. The TD unit has been tested for light-up, acceleration and initial performance. The test was carried out in the presence of Shri K Ramesh, GM (AERDC), Shri G P Ravi Shankar, Technical Director (Propulsion), ADA & his team, Shri. Girish K Degaonkar, CD(AERDC) and AERDC team. Project : Commissioning and Handing over of AMAGB attitude Test rig to Engine Division Achievements : AERDC has commissioned and handed over the LCA-AMAGB attitude test rig to Engine Division (BC). AERDC had taken the responsibility of designing, manufacturing, installation and commissioning of AMAGB attitude test rig at Engine Division. This rig has been indigenously designed and manufactured to cater to the attitude simulation test requirement. The rig can work under the following conditions; Load carrying capacity : Approx. 60 kgs of UUT Pitching upto 360 degrees Rolling upto 360 degrees Hydraulic loading of AMAGB up to 15 kW Running of AMAGB upto 16810 RPM NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 39

Project : Qualification test of AP –Jaguar Achievements : Air Producer(AP)-for Jaguar Engine, project taken under indigenization drive with ““FORM, FIT and FUNCTION” genesis has raced past all pitfalls to hit the testing field within 12 months from the date of preliminary design. AP engine is used to start main engines (ADOUR-804/811) of JAGUAR aircraft. The engine has undergone performance trials at Leh, South Pullu and Khardung-La. The engine is now under qualification tests like g-load, vibration and shock etc. at AERDC. A total of 44+ engines are already on order on HAL of which AERDC has to deliver 14 engines in the development batch starting from 1st quarter of 2023-24. Project : Indigenous FADECs Achievements : In a valiant effort to indigenize the FADECs for the flagship engine design programs of HAL (HTFE-25 and HTSE-1200), AERDC has entrusted its sister division SLRDC for designing the hardware. SLRDC has delivered the technological demonstrator units of FADEC to AERDC of both HTFE-25 and HTSE-1200 engines. The testing is planned in 5 phases. Phase-0 and Phase-I testing has ben completed at AERDC. The control system software (OFP) for “Starting Sequence” is tested with engine harness by connecting engine mounted sensors. The data is monitored on ARINC 429 GUI developed by SLRDC. The CLAW for engine starting sequence is implemented and the actuation of relays & digital output was checked for specified sequence and timing values. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 40

Project : Testing of HTSE 1200 Jet mode Engine with indigenous Valve Block Unit Achievements : The fuel system for HTSE-1200 engine is being designed in modules namely, Pump, metering unit, valve block, atomizers and control system. The valve block unit consisting of 4 valves has been manufactured and tested both in test rig and on the engine successfully. The jet mode engine has been run upto idle speed in the test bed with indigenous valve block. Project : Endurance run of PTAE-W Achievements : PTAE-W in its original version can meet an endurance of 50 minutes. However, for the CATS-W application, an endurance of 120+ minutes is essential. In order to meet this requirement, necessary design modification of the lubrication system was made. The design has been validated by running the engine continuously on the test bed for 125 minutes. The oil tank capacity has been enhanced from 1.65 to 4.2 liter. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 41

Prateek Mehrotra Chief Manager (Design-ATD) HAL, AERDC has been awarded a patent for that it helps in reducing the accumulation of low momentum fluid, thereby improving stability design of a high efficiency centrifugal margins and efficiency. compressor by the patent office, Chennai during the month of September 2022. The This compressor module has been successfully patent is related to the design and development tested on GTSU-110 as a drop-in replacement of a centrifugal compressor module, used as a towards development of its higher power drop-in replacement in GTSU-110 for its higher variant of 127kW. power density variant. The same compressor module with modified air Designed by Prateek Mehrotra (Chief Manager, intake (90 degree bend configuration) has been Design- Aerothermodynamics) and M. used in GTEG-60 engine, a variant of GTSU Devathathan (Ex-Senior Manager, Design- engine. Aerothermodynamics), the impeller is with backswept blades, wherein combination of The same compressor module with flow splitter thickness distribution, blade angle distribution downstream to the radial diffuser and volute has and blade lean angle is defined in such a way been designed for development of Air Producer variant of GTSU engine. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 42

Dr. R. Siva Srinivas Senior Manager (Design) A paper titled “Vibration Response Prediction in Rotor systems with External Damping by Deep Learning using Geometrical Features” has been presented at VETOMAC conference held at BMS College, Bengaluru on Dec 16-18, 2021. The authors of the paper are Dr. R Siva Srinivas (SM-D), Dr. Rajiv Tiwari (Professor, Mech. Engg. Dept., IIT Guwahati), Amar Singh (DGM-D), Girish K Degaonkar (CD-AERDC) and K Ramesh (GM- AERDC). The paper describes the development of Artificial Neural Networks (ANN) algorithm which uses geometric features of bearing housings, unbalance magnitude and phase, rotational speed as inputs and predicts the vibration response of rotor system. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 43

A. Padmavathi Deputy General Manager (Design-AW) Globally, October is celebrated as Cyber Security Awareness Month (CSAM) and this year’s theme is 'See Yourself in Cyber: Together we make it Safer', focusing on the ‘people’ part of cybersecurity, providing information and resources to help spread awareness. Today in this fast moving era, where all things are just a click away, our world is becoming increasingly dependent on Internet of things and needs a stronger cyber security. Cybersecurity Awareness Month serves as a reminder to everyone that there are numerous ways to safeguard, maintain digital hygiene, follow security best practices and strive for a safer cyberspace. When we say See Yourself in Cyber, we mean see yourself in cyber no matter what role you play. As an individual or consumer or entrepreneur, take basic steps to protect your online information and privacy. There are ways to protect yourself online : - Update your software: don’t delay Best Practices  Bad actors will exploit flaws in the system, network defenders are working hard to fix them as soon as they can, but their work relies on all of us updating our software with their latest fixes.  Act promptly! If you see a software update notification don’t delay it, better keep auto-updates ON.  Update the operating system on your mobile phones, tablets and Laptops. And update your applications – especially the web browsers- on all your devices too.  For portable media, perform full scan of hard drives, pen drives and SD cards with an updated antivirus before open/use them. Enable Multi-Factor Authentication (MFA) Best Practices  You need more than a password to project you online accounts and enabling MFA makes you significantly less likely to get hacked. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 44

Think before You Click: Beware of phishing and email Scams Best Practices  Verify before clicking web links received over emails /SMS  Do not open suspicious emails or attachments claiming to be from known senders, if you aren’t expecting.  Check for red flags such as strange email addresses grammatical mistakes or misspellings  Beware of possible malware in email attachments  Never share personal or financial information over the internet Think before You Click: Beware of phishing and email Scams Best Practices  Creating strong passwords is an easy way to improve your cyber security. Strong password include one uppercase letter, one lowercase letter, at least one number and 11 or more characters  Use password managers to generate and remember different, complex passwords for each of your accounts. A password manager will encrypt passwords securing them for you.  Make a habit to use different passwords for different accounts.  Change them periodically.  Avoid saving passwords in browsers.  Enable your phone’s fingerprint or facial recognition feature for authenticating apps. Be Cyber Security aware on social media Best Practices  Avoid sharing sensitive personal details, financial details, DOB, house address and contact details on social media.  Review the privacy and security settings of your social accounts periodically.  Don’t fall for fake news updates coming from unverified accounts. Rely on verified accounts only for news updates.  Think before you act! Avoid clicking on any enticing link received over chat, DM, post, etc.  Block accounts posting objectionable content and report suspicious activity immediately. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 45

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Dr. K V L Narayana Rao Chief Manager (Design-ATH) Aero Engine Research and Design Centre Book Title: Gas Turbine Combustion by Arthur H. Lefebvre and Dilip R Ballal, Third Edition, CRC Press, © 2010 by Taylor and Francis Group. ISBN -13: 978-1-4200-8605-8 (Ebook-PDF) Introduction and Background: This book primarily focuses on the design, manufacture, and operation of gas turbine combustors in applications ranging from aeronautical to power generation. It serves as design manual and research reference in the field of gas turbine combustion. This book is essentially self-contained and as- sumes only a modest prior knowledge of physics and chemistry. The authors are one of the Pioneers in the field of Gas turbine combustors who published many articles/Journal papers in various peer reviewed Journals. The literature referred in this book are cited authentic and reliable. Discussion on salient features, Findings and Usefulness: The combustor aerodynamics discussed in Chapter 4, is useful in predicting the pressure losses for a given combustor geometry. The performance equations and some of the empirical correlations of pattern factor data given in Chapter-4 and Chapter-5 are found to be salient features brought out this book. The chapters on estimation of Combustor geometry, Combustion efficiency, Fuel atomization, Ignition and Heat transfer provides a very useful and fundamental information in the design and development of novel combustor designs. This book offers great help in understanding combustor fundamentals and has a clear purpose in the field of Gas Turbine Combustion. NOVEMBER 2022 | ISSUE 07 | TURBO PULSE | 50