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O ffice N ational d’ É tudes et de R echerches A érospatiales

15 - 17 september 2004 4th European Micro-UAV meeting Toulouse Micro engines for micro drones propulsion Joël Guidez, Clément Dumand, Olivier Dessornes, Yves Ribaud. O ffice N ational d’ É tudes et de R echerches A érospatiales. Outline of the presentation. 1/ Introduction : micro-systems

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O ffice N ational d’ É tudes et de R echerches A érospatiales

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  1. 15 - 17 september 2004 4th European Micro-UAV meetingToulouseMicro engines for micro drones propulsionJoël Guidez, Clément Dumand, Olivier Dessornes, Yves Ribaud Office National d’Études et de Recherches Aérospatiales

  2. Outline of the presentation • 1/ Introduction : micro-systems • 2/ Application to micro-drones • 3/ Energetics micro-systems • 4/ Micro-turbine • 5/ Conclusion and perspectives

  3. 1 / INTRODUCTION • What is a MEMS (Micro Electro-Mechanical System) ? • Miniaturization • Components : silicon, silicon-carbide • Applications : - sensors - actuators - energetics micro-systems SiC Si

  4. puissance RF et transmission filtres digitaux onvertisseur CAD capteur de température Accelerometer What ’s MEMS ? a sensitive element… Actuator (switch) …frequently in silicon Gear Miror packaging electronics Pressure sensor cea Leti 4

  5. 1 mm TMIT (Tokyo) But, it ’s also : an energetics micro-system Micron-scale counterflow heat exchanger 20 mm Micro-turbine MIT 5

  6. 2 / APPLICATION TO MICRO-DRONES • Mini and micro-drones • fixed wing/rotating wing • flapping wing • Main specifications Microbat Caltech 6

  7. Various MAV versions

  8. Microdrone : specifications • «Flying binocular» : system for collection of proximity information • Dimension up to 15 cm : length and wingspan • Hovering, flight at 50 km/h • Autonomy : 20 mn to 1h • Power : 20 to 50 W • Mass  80 g • Data transmission in real time (Video or other)

  9. 3 / Energetics micro-systems : a lot of micro-systems and actors • Micro-turbine : • MIT, Tokyo, Hoseï, Sendaï University, Tokyo Metropolitan Institute of Technology, IHI, Onera, VKI, ERM, Leuwen University, National University of Singapore... • Reciprocating free piston engine : • Georgia Tech, Berkeley, Birmingham University, KAIST (Corée) • Wankel Micro-motor : • Berkeley, Birmingham University • Thermoelectric micro-generator : • USC, Tohoku University, CEA, Onera, National University of Singapore • Thermophotovoltaïc generator : • National University of Singapore, California State Polytechnic University ... • Liquid rocket engine : • MIT, Uppsala University, QinetiQ, LAAS

  10. Reciprocating free-piston engine stator of electric generator Exhaust valve Main shaft piston Inlet valve Combustion chamber Electrical leads Single variation KAIST Korea 1 mm thick glass Combustion chamber 1 mm Piston 2 x 2 mm cea Leti 10

  11. Mini and micro-Wankel engine • Presently 2.4 mm Si model • Aim : Si fabrication, 1 mm x 300 µm • 10 to 100 mW • SiC-coated Si 13 mm 3 W 10000 rpm 11 Berkeley

  12. MIT Micro-turbine

  13. ONERA micro-turbine « upper combustor without premixed channel » hydrogene Combustion chamber exhaust turbine .,.. compressor air inlet

  14. THERMOELECTRIC GENERATOR Thermoelectric microgenerator Thermoelectric wall Combustion chamber Hot Junction Ceramic Metallic Conductor P N P N P Semi conductor P or N i U Cold junction Ge-Si : 3 W/cm² h 5% « Swiss roll » USC

  15. Reciprocating free piston engine rotating engine (Wankel) turbine engine thermoelectric system thermophotovoltaïque system Difficulties Comparison between micro-systems Advantages Well known Well known Good conversion mecanic/electric Quasi static system Relatively simple System quasi static Heat losses, friction, low frequency Low rotating speed and low power Complexity, high rotating speed, journal bearing Connectic, catlytic combustion To control this technique

  16. 4 mm 4 / MICRO-TURBINE • Thermodynamic cycle • Energetic balance • Small scales problems... • Combustion/ignition MIT 200 mm

  17. Ch comb. T Thermodynamic cycle C Brayton-Joule cycle hth = 1 - 1/tc (g-1/g) tc = 3 hth=0.27 tc = 4 hth=0.33 hc=0.7et ht=0.6, thus h cycle 0.11 à 0.14 T Ch comb T C S

  18. 56 W convection 8 W radiation 48 W T = 288 K Air flow air 0.4 g/s Fuel : 46.6 g/h T = 670 K compressor T = 930 K stator T = 1600 K chamber T = 840 K turbine Net Power 34 W Internal Heat Exchanges Thermal losses in exhaust gases 56 W ( T = 1103 K ) Work efficiency External Heat Losses convection 8 W 430 W 3.4 % radiation 48 W MICRO-TURBINE : ENERGETIC BALANCE 23 W 51 W 33 W 19 W 3 W 6 W 34 W 82 W P comb = 503 W 28 W 16 W 9 W 12 W Net power 17 W Global efficiency 3,4 % 18

  19. 1,7%<global efficiency<10% Fuels : H2, CxHy COMPARISON OF PERFORMANCES 10000 Specific energy Autonomy : 1 h 20 mn Wh/kg 1000 MICRO TURBINE 100 BATTERIES 10 Specific power SUPER CAPACITORS W/Kg 1 1 10 100 1000 10000 100000

  20. Micro-scale combustorsSpecific problems • 1/ Low Reynolds number (< 1000) • 2/ Residence time close to reaction time (Da around 1) • 3/ Important heat losses (ratio S/V unfavourable) • 4/ To improve ignition system (reusable) • 5/ Quenching, self ignition in premixed channel mixing

  21. Combustion :mixing, residence time, quenching fuel Mixing fuel/air Mixing fresh gas/burned gas air Da = residence time/ reaction time Da > 1  c  0,5 ms, thus Vmin = m’.c.r.T/P  (4 mm)3 Quenching distance : d// = Pe.a/SL  0,2 mm (H2)  0,7 mm (Propane)

  22. 0D model results PASR PSR Residence time in the micro-combustor =t s / t m Heat losses Mixing ratio

  23. ONERA ’s CFD code Development tool in order to select the best configurations of the micro-combustor m’ = 0,1 g/s P = 3 bar Tp = 950 K Model : Ecklund (7 reactions) Equi.ratio = 0,6

  24. Set-up for combustion tests Air and fuel inlet Injection strut cooled, air and fuel inlet Micro-combustion chamber Window for optical measurements (IR caméra, Raman...) Vessel cooled by nitrogen Exhaust Combustion products Micro-combustor Vessel with micro-combustor

  25. 5 / SUMMARY AND CONCLUSIONS PhD work: > experimental study of mixing without combustion : 2004 and 2005 > computations : 0D and 3D (for the design of the future combustors) Combustion tests : > to carry out ignition tests (hot wire or film, electrical discharge) > to assess the flame stability (influence of heat losses, equivalence ratio, type of fuel (hydrogen or hydrocarbon) ... > to evaluate the combustor efficiency (heat balance, RAMAN scattering) Micro-systems : > to study new concepts of micro-turbines and specific combustors for direct electrical generation (catalytic combustion)... > thrust and journal bearings Cooperations : > with other ONERA’s department for PLIF, RAMAN, thermoelectricity, igniter, flow simulation inside micro-compressor ... > CEA (LITEN), INPG/LEG, Silmach, NEDO (post doc.), TMIT ... Manufacturing, mehanical/electrical conversion

  26. 5 / MICRO-TECHNOLOGIES Micro-manufacturing Centrifugal Compressor Si, Sic, Si3N4 Centripetal turbine MIT

  27. 200 mm GAS THRUST BEARING AND JOURNAL BEARING • Rotating speed about 1 million rpm MIT

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