CRANFIELD UNIVERSITY SCHOOL OF MECHANICAL ENGINEERING Ph.D. THESIS AcademicYear 1996/7 Louay ALEED VARIABLE CYCLE PROPULSION SYSTEMS FOR A SUPERSONIC CIVILTRANSPORT Supervisor: Dr. P. Pilidis April 1997 This thesis is submitted in partial fulfilment of the requirements for the Degree of Doctor of Philosophy. Summary Summary The different aspects of overall performance of three variable cycle engines (VCE) candidatesfor future supersoniccivil transport are analysedin this work. These aspects concern the design and off-design points performance, the airframe engine integration and variable geometrycompressor and turbine design and performance. The three engines are compared to a traditional turbojet. The variable compressor maps were obtained with their running lines for the whole mission profile including the transition mode from medium býpassratio to a lower bypassratio turbofan. The specific fuel consumption (SFC) of the VCEs showed a significant improvement, especially at subsonic cruise, relative to a Turbojet engine. The extent of the variable geometry on the compressor stator angles, mixing area and the nozzle throat and exit areasis evaluated. The Fuel bill is estimatedfor two standardmission profiles. The effect of installation is estimatedon an isolated nacelle. A sizing calculation is carried out for the whole nacelleincluding the intake and the nozzle. The drag due to the friction, pre-entry, afterbody and the shock waves is calculatedin order to estimated the installed performanceof the three engines. In the search of improving the VCE performanceat subsonic cruise, the use of variable geometry at the low pressure turbine for the Turbofan-Turbojet engine is investigated. The effects of varying the LP turbine guide vanes stagger angle on the engine performance and component parametersare analysed. The turbine efficiency and non-dimensionalmass flow changesdue to the use of variable geometry are estimated. An updated version of the Turbornatch program was corrected and tested in order to study variable cycle engines,especially to simulatethe transition from one mode to another. II Acknowledgments Acknowledgments I would like to thank my supervisor Dr. P. Pilidis, for his help and friendship. Thanksalso to Barbara Wilsonfor her kindnessand help. Thanks to my parents andfamily Maha, Rami and shadi I would like to thank the Higher Institute of Applied Science and Technology (HIAST)for theirfinancial support. Finally, thanks to God who created us and gave us the hope and the intelligence to undertakesuch a work. Hi Table Of Contents TABLE OF CONTENTS 11 SUMMARY 90........................... a ..... * ..... 000*00............. *. **** ........... *. *.. * ......... 111I ACKNOWLEDGEMENTS .................................................................................... OF CONTENTS IV TABLE ........................................................................................ FIGURES vi LIST OF ........................................................................................... ix NOTATION .................0 .... 0.. *.... 0 ................ oo* ..... 000** .......................... 00 ... CHAPTERI Introduction ...................................................................I 1.1-The FutureSST 2 ................................................................................ 1.2-Aim Of The Work 7 ............................................................................ 1.3-Bibliograhpic Review 9 ....................................................................... 2 Variable Cycle Engine Philosophy CHAPTER ..........................14 2.1- Introduction 15 ................................................................................... 2.2- Engine With Variable Geometry Components 16 ................................ 2.3- Engine With Two Design Points 17 .................................................... 2.4- Matching Two Cycles In One Engine 20 ............................................. 2.5- Three CandidatesVCE For Future SSTs 28 ........................................ 2.6- AdvantagesAnd DisadvantagesOf VCE 30 ........................................ Design Point Analysis CHAPTER3 .................................................41 3.1 Introduction 42 - ................................................................................... 3.2-SupersonicDesign Point Performance 43 ............................................. 3.3-SubsonicDesie-n Point Performance 48 ................................................ 3.4- Take-off Noise Consideration 52 ........................................................ CHAPTER 4 Variable Geometry Compressor Design Performance and . ..............................................54 4.1 Introduction 55 - ................................................................................... 4.2- Variable Cycle Engine Simulation 56 .................................................. 4.3- CompressorDesign 58 ........................................................................ 4.4- Turbine Design 63 ............................................................................... 4.5- ResultsAnd Performance 66 ............................................................... 4.6- Fuel Bill 75 ......................................................................................... 4.7- Conclusion 78 .................................................................................... IV Table Of Contents ClUPTER5 Airframe Engine Integration ......................................95 5.1 Introduction - ................................................................................... aA v 5.2- Thrust And Drag Definition ýý ...........................................................97 5.3 Nacelle Sizing ................................................................................99 5.4- Drag Calculation 104 .......................................................................... 5.5- Installed Thrust 107 ............................................................................ 5.6- Effect Of Bypass Ratio On SupersonicDrag 109 5.7- RemarksAnd Conclusion III ............................................................. CHAPTER 6 Variable Geometry Turbine Design Performance and ................................................121 6.1 122 -Introduction .................................................................................. 6.2-Variable Area Turbine Design Considerations 127 ............................... 6.3-Turbofan-Turbojet Variable Geometry Low Pressure Turbine 130 ....... 6.4- Effect Of Adjustable Guide Vanes On Turbine Efficiency And Non-Dimensional Mass Flow 136 ....................................................... 6.5- Conclusion 138 .................................................................................. CHAPTER 7 Conclusion ...................................................................148 7.1 Conclusions 149 - ................................................................................. 7.2- Contribution 153 ................................................................................ 7.3- FurtherWork 154 ............................................................................... REFERENCES 155 ......................................................................................... APPENDIX A Modifications Of TurbomatchProgram ............... A. 1 - A. 15 APPENDIX B Turbofan-TurbojetEngine ..................................... B.1 - B.37 APPENDIX C CA Mid-TandemFan Engine ..................................... - C.27 APPENDIX D Double BypassEngine ..........................................D. 1 - D.23 APPENDIX E Parameters Compressor& Turbine Design .............E. 1 - E.5 V Table Of Figures TABLE OF FIGURES Figure 1.1 Future SST Aircraft 4 ....................................................................... Figure 1.2 Comparison MM ConventionalEngines 5 of and ............................. Figure 2.1 Effect Of SupersonicBypass Ratio On LP CompressorMatching 19 Figure 2.2 Explanation To Variable Geometry 31 .............................................. Figure 2.3 Effect Of Overall PressureRatio On The HPT Non-Dimensional Mass Flow For Different TET And BPR At SubsonicMode... 32 Figure 2.4 Effect Of SupersonicHPC PressureRatio On LPT NI?MF 33 ........ Figure 2.5 Effect Of HPC PressureRatio On LPT Non-Dimensional Mass Flow For Different Overall PressureRatios 34 .................................. Figure 2.6 Effect Of PressureRatios On Mixing Total Pressure Point A (OPR TET 1300, BPR 2.3) 35 =6.56, = = ...................... Figure 2.7 Effect Of PressureRatios On Mixing Total Pressure Point B (OPR TET 1200, BPR 1.8) 36 =7.4, = =, ........................ Figure 2.8 Effect Of PressureRatios On Mixing Total Pressure Point C (OPR TET 100 BPR 1.3) 37 =8.85, =I , = ...................... Figure 2.9 Example Of A VCE LP CompressorRunning Line 26 ...................... Figure 2.10 Turbofan-Turbojet Engine 38 ........................................................... Figure 2.1.1 Mid-Tandem Fan Engine 39 .............................................................. Figure 2.12 Double BypassEngine 40 ................................................................. Figure 3.1 Turbojet Engine SupersonicDesign Point Performance 43 ................ Figure 3.2 Turbofan-Turboj SupersonicDesign Point Performance 44 et ............ Figure 3.3 Mid-Tandem Fan SupersonicDesign Point Performance 45 .............. Figure 3.4 Double BypassEngine SupersonicDesign Point Performance 45 ...... Figure 3.5 Turbofan-Turbojet SubsonicDesign Point