A performance evaluation of MEMS-based micronozzles

Abstract

An investigation is made into the modeling, design and testing of micron scale Laval nozzles. Such nozzles can provide orbital maneuvering for small spacecraft or attitude control and stationkeeping for their larger counterparts. The flow in the nozzle is modeled by means of a two dimensional finite volume NavierStokes simulation which predicts viscous losses with a decrease in nozzle scale. Calculations show mass flow is reduced to 93% of the ideal in viscid flow for a throat Reynolds number of 500. The nozzles modeled are fabricated through deep reactive ion etching in an inductively coupled plasma. Nozzle throat dimensions of 30 microns reduce to 20 microns over the depth of the nozzle. Nozzle testing reveals choked conditions exist, and the flow rates are similar for different geometries of the same throat dimensions.