Numerical Investigation on Two Streamline-Traced Busemann Inlet-Isolators

Abstract

This paper presents a computational fluid dynamics (CFD) study of flow characteristics within three-dimensional Busemann inlet with isolator models. The primary aim of the study was to compare various performances between two streamline-traced inlets, one with a square capture shape and the other with a circular capture shape; both were based on a truncated Busemann inlet. In addition, a square-to-circular isolator and a circular isolator were added after the square inlet and the circular inlet, respectively, in order to assess the impact of the inlet on the flowfield of the isolator. The investigation reveals that because of the existence of dihedral angle in Busemann inlet, boundary layer separation occurs in the square inlet configuration, which makes it having the starting Mach number of about 0.2 higher than that of the circular inlet; besides, the total pressure recovery coefficient of the square inlet at the off-design conditions is about 6% lower than that of the circular one. The dihedral angle also affects the isolator performance, and the resultant maximum sustainable back pressure of the square-to-circular isolator is 7% lower than that of the circular isolator. It was finally concluded from present CFD studies that the flow conditions at the exit of the inlet do have a notable influence on the flow field of the isolator, and the circular inlet with the isolator has overall better performance.