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Engine Design and Performance Analysis for Small-Scale Micro Air Vehicles

This document presents a comprehensive analysis of engine concepts suitable for small-scale Micro Air Vehicles (MAVs) focusing on achieving high power density and efficiency. It explores various engine types, including Tesla turbines, Otto engines, and hot air engines, assessing their performance for a 0.6-gram MAV that requires 125 W/kg power density with 5% efficiency. The study also examines hydrogen peroxide as a clean fuel source, along with catalytic reactions for power generation. The conclusions highlight the potential and limitations of each engine type in MAV applications.

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Engine Design and Performance Analysis for Small-Scale Micro Air Vehicles

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  1. DESIGN ANALYSISfor a SMALL SCALE ENGINE by Tim van Wageningen

  2. Contents • - Motivation • - Concepts • Performance Analysis • Conclusions • Questions ±40 min 2 MOTIVATIONS - CONCEPTS – PERFORMANCE I / II / III - CONCLUSIONS

  3. Nature Technology small large scale → Atalanta project 3 MOTIVATIONS - CONCEPTS – PERFORMANCE I / II / III - CONCLUSIONS

  4. Micro Air Vehicle Flapping Wing Mechanism MAV • Designed by Casper Bolsman • 0.6 gram • Performance estimate: • 0.5 W power output • Needed power density of • system: 125 W/kg • 6 minutes of flight time with • 5% efficiency 4 MOTIVATIONS - CONCEPTS – PERFORMANCE I / II / III - CONCLUSIONS

  5. MAV in Action 5 MOTIVATIONS - CONCEPTS – PERFORMANCE I / II / III - CONCLUSIONS

  6. Hydrogen Peroxide • - Master thesis of ArjanMeskers at the PME • department, TU Delft • Chemical energy: high energy density • - Monopropellant • - Clean products: oxygen and water vapor • - Example catalysts: -Manganese oxide • -Silver • -Platinum 6 MOTIVATIONS - CONCEPTS – PERFORMANCE I / II / III - CONCLUSIONS

  7. Catalytic Reaction in Action 7 MOTIVATIONS - CONCEPTS – PERFORMANCE I / II / III - CONCLUSIONS

  8. Thesis Assignment • Find an engine concept that: • is suitable for the MAV • 125 W/kg • 5% efficiency • uses hydrogen peroxide as fuel 8 MOTIVATIONS - CONCEPTS – PERFORMANCE I / II / III - CONCLUSIONS

  9. Possibilities 9 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  10. 3 different approaches Turbine Piston Cylinder + + + + + 10 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  11. Concept I: Tesla Turbine Engine • + Easy implementation • + Theory of Tesla Turbine • predicts good efficiency at • small scale • Conversion from rotation • to linear motion + + 11 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  12. Concept I: Tesla Turbine Engine + + 12 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  13. Concept II: Otto Engine • + Proven concept on regular • scale • Projects in literature show • bad performance because of • fluid leakage problem • - Implementation difficult + 13 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  14. Concept II: Otto engine + 14 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  15. Concept III: Hot Air Engine • + Easy implementation • + Promising scaling aspects • because heat transfer is more • effective • Poor performance on regular • scale + + 15 MOTIVATIONS - CONCEPTS – PERFORMANCE I / II / III - CONCLUSIONS

  16. Concept III: Hot Air Engine + + 16 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  17. Performance • - What influences the performance of • these concepts? • - Concept I • - Concept II • - Concept III • Are the concepts suited for the MAV? • Power density • Efficiency 17 MOTIVATIONS - CONCEPTS - PERFORMANCEI / II / III - CONCLUSIONS

  18. Concept I: Tesla Turbine Engine 18 MOTIVATIONS - CONCEPTS - PERFORMANCEI / II / III - CONCLUSIONS

  19. Concept I: Tesla Turbine Engine: model Assumptions: Laminar flow No entrance effects Incompressible fluid 19 MOTIVATIONS - CONCEPTS - PERFORMANCEI / II / III - CONCLUSIONS

  20. Power Efficiency Pressure difference Length of belts (radius of discs) Height of gap (spacing between discs) 20 MOTIVATIONS - CONCEPTS - PERFORMANCEI / II / III - CONCLUSIONS

  21. Measurements with small scale Tesla turbines Pressure difference: ~20 kPa Measured Performance 45 mW 18% efficiency Estimated power density: 2 W/kg [2] V.G. Krishnan et al. A micro Tesla turbine for power generation from low pressure heads and evaporation driven flows. Transducers, 11:1851 – 1854, June 2011. 21 MOTIVATIONS - CONCEPTS - PERFORMANCEI / II / III - CONCLUSIONS

  22. Concept I, Tesla Turbine Engine: conclusions • Power density is too low: • pressure difference • must be increased • considerably • Simple model + measurements • show that TTE is not suitable for the • current size MAV 22 MOTIVATIONS - CONCEPTS - PERFORMANCEI / II / III - CONCLUSIONS

  23. Concept II: Otto Engine 23 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  24. Concept II, Otto Engine: combining 3 models Catalytic Reaction Exhaust Flow Heat Loss + + 24 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  25. Catalytic Reaction: model Drop on a catalytic surface Similar conditions as during experiments Energy Balance: 25 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  26. Catalytic Reaction: model [1] A.J.H. Meskers. High energy density micro-actuation based on gas generation by means of catalyst of liquid chemical energy. Masters thesis, TU Delft, 2010. 26 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  27. Catalytic Reaction: high fuel concentrations 27 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  28. Exhaust Flow: model Compressible flow through a round nozzle Based on momentum equation 28 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  29. Heat transfer Heat is transferred via -conduction -convection -radiation 29 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  30. Concept II, Otto Engine: combining models + + = • Dealing with model uncertainties: 30 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  31. Otto Engine: observations -Reaction times are fast enough -Trade off for fuel used per cycle -Condensation in cylinder 31 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  32. Concept II, Otto Engine: Results • Model shows performance above • the current requirements of the • MAV (125 W/kg @ 5% efficiency) 32 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  33. Concept II, Otto Engine: considerations • Model neglects: • fluid leakage through cylinder/piston gap • fluid friction at exhaust • fuel delivery system • Condensation in cylinder problem • needs to be addressed 33 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  34. Concept III: Hot Air Engine 34 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  35. Concept III, Hot Air Engine: models Catalytic Reaction Heat Reservoirs Heat Loss + + 35 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  36. Concept III, Hot Air Engine: Catalytic Reaction Constant temperature Mass balance 36 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  37. Concept III, Hot Air Engine: Heat Reservoirs Under reversible conditions Estimate for heat transfer rates Schematic • Using definition • Fouriers law • Optimistic and • pessimistic value 37 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  38. Model Results + + = Resulting performance of model 38 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  39. Considerations for Small Scale Hot Air Engine • Model neglects losses of • fluid flow between piston cylinder gap • heat leakage of Decomposition Unit to • the working fluid 39 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  40. Conclusions for Small Scale Hot Air Engine • Heat transfer is not yet fast enough • on this scale, which results in low • performance • Concept III is not suited for the MAV 40 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  41. Overall Conclusions • Of the considered possibilities, the • small scale Otto engine is the best • option for the MAV: • Power density at 5% efficiency: • Concept 1: << 2 W/kg • Concept 2: 245 – 440 W/kg • Concept 3: 0.5 – 8 W/kg 41 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  42. Overall Conclusions • Actual implementation • of concept II requires • more detailed analysis: • - Solving the fluid leakage problem • - Fuel pump • Exhaust port • Condensation 42 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS

  43. Thank You! 43 MOTIVATIONS - CONCEPTS - PERFORMANCE I / II / III - CONCLUSIONS -END

  44. Detailed slides 44 DETAILED SLIDES

  45. Scaling? Engine 2 S = 0.5 L = 5 A = 2.5 V = 1.25 Engine 1 S = 1 L = 10 A = 10 V = 10 Scaling factor Length Area Volume 16 PERFORMANCE

  46. Approach of others? 6 PREMILAIRY RESEARCH

  47. Possibilities 7 PREMILAIRY REASEARCH

  48. Power Efficiency Pressure difference Length of belts (radius of disks) Height of gap (spacing between disks) 40 PERFORMANCE

  49. Energy flow in concepts Carnot cycle = 7 CONCEPTS

  50. Carnot Cycle zero power output! 8 PERFORMANCE

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