Structure of flow fields in low pressure impactor

Abstract

In order to clarify the detailed flow fields of impinging jets in a low pressure impactor, nitrogen and argon flow fields are investigated experimentally and numerically at a relatively small range of Pdown/Pup, where Pdown is the downstream stagnation pressure and Pup the upstream stagnation pressure. The pressure at the center of collection plate, Pc, is measured in addition to the flow visualization by Laser Induced Fluorescence (LIF) technique, which is used in previous study. Furthermore, the flow fields in a low pressure impactor have been simulated by solving the axisymmetric Euler equation through Harten-Yee TVD method. The effects of Pdown/Pup and H/D on flow fields are examined in detail, where H is the jet-to-plate distance and D the nozzle diameter. The calculated shock wave position on jet axis and the pressure at the center of collection plate are in reasonable agreement with the experimental results. It is found that the structure of flow fields changes drastically at a certain value of Pdown/Pup and there exist hysteresis phenomena in the relationship between the value of Pc/Pup and that of Pdowb/Pup for both gases. The formation of the separation bubble at a certain value of H/D is discussed. © 1998 Taylor & Francis Group, LLC.