Cavitation at Micro-Scale in MEMS Fluid Machinery

Abstract

Cavitation has long been a concern in the engineering of fluid machinery. The state of the art in MEMS is now such that micro-machines are being designed and built which, by conventional macro-world criteria, can operate in cavitating regimes. Specifically, cavitation in 900-micron-chord cascades characteristic of micro-centrifugal pumps was investigated through analysis and experiment for working fluids of water and ethanol. The primary finding was that cavitation in these micro-devices exhibited static and dynamic behavior very similar to that expected in large scale flows. Furthermore, conventional cavitation models coupled to 2D and 3D CFD simulations matched the micro-scale data well in predicting the onset of cavitation and the length of the cavitation zones. Also, no mechanical damage from cavitation was found. This implies that vacitation in micro-machines will offer no unusual surprises to device designers.