Numerical Solutions for Ultra-Micro Wave Rotors (UµWR)

‡Starting in 1995, with the MIT “Micro Gas Turbine” project, the mechanical engineering research world has explored more and more the idea of “Power MEMS” 1 . Microfabricated turbomachinery like turbines, compressors, pumps, but also electric generators, heat exchangers, internal combustion engines and rocket engines have been on the focus list of researchers for the past 10 years. The reason is simple: the output power is proportional to the mass flow rate of working fluid through the engine, or the cross-sectional area and the mass or volume of the engine is proportional to the cube of the characteristic length, thus the power density (Power/Mass=L -1 ). This is the so-called “cube square law”. Although in theory everything is perfect, the following investigations showed that there are many engineering challenges at microscale and the solutions found in the past half of century for large scale mechanical devices do not necessarily apply to the new design space. This paper studies the possibilities of incorporating a wave rotor to an ultra-micro gas turbine. It discusses the advantages of wave rotor as topping units for gas turbines, especially at microscale and proposes some designs of ultra-micro wave rotors. The numerical simulations of these wave rotors are presented, results obtained using FLUENT, a Computational Fluid Dynamics (CFD) commercial code.