Study of Strut Interference in High-Speed Flows

Abstract

Strut-support interference effects were investigated at a nominal Mach number of 6. Cylinder and rhombus models are used; moreover, models called half shock-bump (SB) and SB applied to the front and both sides of the shock-bump shape are used. This is beneficial for free-stream flow recovery around the model surface by bumping the compression and expansion waves at a unit Reynolds number of approximately 17.8 x 103/m and a total enthalpy of approximately 1.9 MJ/kg. A quantitative density field analysis is conducted using the background-oriented schlieren technique, which is validated by measuring the shock stand-off distance and density increase rate on a hemisphere model. In this study, flow interference is divided into the measurements of the recompression shock zone thickness as a wake interference and the free-stream flow density recovery beyond the oblique shock as a strut interference. In the SB model, the thickness of the recompression shock zone is approximately 4.4 +/- 0.2 mm, which is a reduction of approximately 53% compared with the cylinder model. In the oblique shock wave height measurements, defined by measuring the intersection of the increasing and decreasing points of density, the SB model shows a height of 16.4 mm, which is approximately 33.6% less than the 24.7 mm height of the cylinder model. In addition, the free-stream flow density beyond the oblique shock wave in the SB model is found to have an approximately 10% deviation from the free-stream density of 0.016 kg/m3, which is more effective than the 106% higher value in the cylinder model. Through such studies of flow interference, the effect of the SB shape on the strut-support is verified.