Supersonic flow in miniature nozzles of planar configuration

Abstract

Supersonic flow of nitrogen gas through miniature nozzles of planar configuration was investigated experimentally and compared with numerical simulations to assess the applicability and accuracy of the various viscous-flow models. The design Mach number of the nozzles is 3, and the inlet pressures range from 0 to 10 atm (gauge). The measured thrust of the meso nozzle with a throat area of 0.773 mm2 agreed well with the numerical solution (96%). The agreement of the micro nozzle, with a throat area of 0.0625 mm2, decreased to 80% for pressure differences beyond the design flow condition. At low-pressure differences, separated flow occurred after the shock in the nozzle, causing unstable and asymmetric velocity distributions on the nozzle exit plane. Thrust was found to be not only a function of pressure difference but also a function of the flow history. The numerical simulation was successful in modeling these effects, but at different pressures.