Experimental Study on Aerodynamics of Microelectromechanical Systems Based Single-Crystal-Silicon Microscale Supersonic Nozzle

Abstract

In this paper, the design, microfabrication, and direct measurement of the static pressure distribution for the aerodynamics of a single-crystal-silicon microscale supersonic nozzle are described. The microscale supersonic nozzle has a convergent–divergent section and a throat area of 100μm × 300μm. The microscale supersonic nozzle was fabricated by silicon bulk micromachining technology. The degree of the rarefaction of nozzle flow was determined by the Knudsen number (Kn). The operation envelope that determines whether the continuum or rarefied flow assumption is appropriate can be expressed as a function of Kn and related parameters. The effect of nonadiabatic operation on microscale nozzle flow was investigated on the basis of wall heat transfer. These physical correlations were taken into account for the classical Shapiro's equations to analyze the microscale nozzle flow aerodynamics (Shapiro, 1953, The Dynamics and Thermodynamics of Compressible Fluid Flow, Ronald, New York, Chap. 7,8; Greitzer et al., 2006, Internal Flow, Cambridge University, Cambridge, UK, Chap. 2,10). Furthermore, the solutions of Shapiro's equations were compared with the experimental results by the authors and other research institutions in order to demonstrate the validity of the proposed aerodynamics design concept for microscale continuum flow.