Experimental results for a microscale ethanol vapor jet ejector

A microscale jet ejector driven by ethanol vapor is designed and tested to induce a suction draft using a supersonic converging–diverging micronozzle. A three-dimensional axisymmetric nozzle is fabricated using electro-discharge machining to produce a throat diameter of 187 µm with an expansion ratio of 3:1. The motive nozzle achieves a design mass flow efficiency of 93% compared to isentropic calculations. Two different ejector area ratios are compared using ethanol vapor and nitrogen gas separately to motivate and entrain ambient air. The experimental data indicate that the ejector can produce a sufficient suction draft to satisfy both microengine mass flow and power off-take requirements to enable its substitution for high-speed microscale pumping turbomachinery.

[1]  S. Spearing,et al.  Microfabrication of a high pressure bipropellant rocket engine , 2001 .

[2]  Luc G. Fréchette,et al.  Design of a Microfabricated Rankine Cycle Steam Turbine for Power Generation , 2003 .

[3]  Masayoshi Esashi,et al.  MEMS-based components of a miniature fuel cell/fuel reformer system , 2004 .

[4]  P. W. B. Semmens,et al.  How steam locomotives really work , 2003 .

[5]  Kenneth S. Breuer,et al.  Viscous Effects in Supersonic MEMS-Fabricated Micronozzles , 1998, Micro-Electro-Mechanical Systems (MEMS).

[6]  Jeffrey H. Lang,et al.  MICRO-HEAT ENGINES, GAS TURBINES, AND ROCKET ENGINES -THE MIT MICROENGINE PROJECT- , 1997 .

[7]  I. Alatiqi,et al.  Evaluation of steam jet ejectors , 2002 .

[8]  C. Livermore,et al.  Design of a MEMS-based microchemical oxygen-iodine laser (/spl mu/COIL) system , 2004, IEEE Journal of Quantum Electronics.

[9]  Jonathan M. Protz An assessment of the aerodynamic, thermodynamic, and manufacturing issues for the design, development, and microfabrication of a demonstration micro engine , 2000 .

[10]  Li Wang,et al.  Fabrication and Testing of a High-Speed Microscale Turbocharger , 2008, Journal of Microelectromechanical Systems.

[11]  Dorian Liepmann,et al.  Design and Fabrication of a Silicon-Based MEMS Rotary Engine , 2001, Micro-Electro-Mechanical Systems (MEMS).

[12]  Chiang Juay Teo,et al.  Hydrostatic Gas Journal Bearings for Micro-Turbomachinery , 2005 .

[13]  Nobuhide Kasagi,et al.  Development of Large-entrainment-ratio Micro Ejector for Catalytic Combustor , 2005 .

[14]  J. Mueller,et al.  A micromachined vapor jet pump , 2005 .

[15]  Ken Balkwill Engineering Sciences Data Unit (ESDU) , 2009 .

[16]  K. Annen,et al.  Linearly-Oscillating Miniature Internal Combustion Engine (MICE) for Portable Electric Power , 2003 .

[17]  Kyle Jiang,et al.  Design and fabrication of a micro Wankel engine using MEMS technology , 2004 .