Effect of Primary Flow Mach Number on the Non-mixed Length in a Two-Dimensional Supersonic Ejector

Abstract

Understanding the flow physics of confined supersonic jet is of primary importance in the design of the supersonic ejector [1] systems. Supersonic ejectors are reportedly used in gas dynamic lasers, wind tunnels, propulsive devices, and fuel cells. One important parameter of study in such device is non-mixed length [2] (NML). A schematic of the flow field observed in a supersonic ejector is shown in Fig. 1. Non-mixed length is defined as the zone where primary and secondary flows maintain distinct characteristics, visually [3]. Conventional techniques like pressure measurement have limitations in determining NML precisely due to constraints in placing the number of pressure sensors, spatially. Optical diagnostics tool like planar laser Mie scattering [4] (PLMS) helps to probe the flow better. This chapter explores the effect of primary flow Mach number (1.5, 2.0, 2.5, and 3.0) on the non-mixed length at different primary flow stagnation pressures (5–10 bar) using wall static pressure measurements and PLMS technique. For this experimentation, an existing supersonic gaseous ejector facility is utilized. Air is used as the working fluid in both primary and secondary flow.