Numerical investigation of supersonic annular flow about struts of various thicknesses

Abstract

Introduction T HE objective of this numerical study is to investigate flow development in the vicinity of a strut (finite-length fin) of various thicknesses that intersects curved endwalls with well-developed turbulent boundary layers for weak-to-strong interaction strengths. To accomplish this, four diamond-shaped, symmetric struts were placed circumferentially equidistant in an annular flow passage with a steady supersonic core flow. This type of application may exist, for example, in dual combustion ramjets with supersonic annular flow or other configurations where struts are needed between the cowl and centerbody. The current investigation extends previous studies by Williams et al.' by examining the influence of strut thickness on interaction phenomena induced by each strut configuration. The interactions occur in an annular flow passage with convex and concave curved endwalls for the inner and outer walls, respectively, and include the effect of crossing shocks between struts. The inner-toouter wall radius ratio is 0.7, the annular gap-to-strut chord ratio is 0.7, and the strut chord is 2.54 cm long. The maximum thickness of the struts examined includes 0.125, 0.188, 0.25, and 0.5 chord lengths, which corresponds to strut half-angles of 7, 11, 14, and 26.5 deg, respectively. The contraction ratios for the four 14and 26.5-deg struts, 1.09 and 1.19, respectively, are less than the maximum permissible value for Mach 3 of 1.39, so that these supersonic flows can be established experimentally. The turbulent boundary layers on the walls of the annular duct are roughly 0.15 strut chords thick at a location 0.5 chords upstream of the strut and the inviscid core has a nominal Mach number of 3.0. The calculations were made at a Reynolds number based on the strut chord of 3 x 10.