Effects of bleed hole size on supersonic boundary layer bleed mass flow rate

Abstract

The bleed hole diameter, depth, and boundary layer thickness are key design parameters of a supersonic bleed system. The evolution trend of single-hole bleed flow coefficient with the ratio of boundary layer thickness to bleed hole diameter and the ratio of bleed hole depth to diameter is investigated by numerical simulations under choking and non-choking conditions. The results show that the subsonic leading edge of the circular hole and the subsonic part of the boundary layer are the main factors causing lateral flow of the bleed hole. The effect of diameter on bleed mass flow rate is due to the viscous effect which reduces the effective diameter. The larger the ratio of displacement thickness to bleed hole diameter, the more obvious the viscous effect is. The depth affects bleed flow rate by changing the opening and closing states of the separation zone. When a certain depth is reached, the development of the boundary layer reduces the effective captured stream tube and thus reduces the bleed mass flow rate. The main objective of the study is to obtain the physical mechanism of the bleed hole size parameters affecting the bleed mass flow rate, and to provide theoretical guidance for the selection of the size of bleed holes in the design of a porous arrays bleed system in hypersonic inlets.

Parameter Influence on the Porous Bleed Performance with & without Shock-Boundary Layer Interaction

“…In contrast to experiments, numerical investigations make extracting the mass flow rates for individual holes feasible. Nevertheless, recent numerical studies [7,[14][15][16][17][18] lack in showing and analyzing the local mass flow rates. Also, the change of the flow field in the holes along the porous bleed is unregarded.…”

Mixing and combustion in supersonic/hypersonic flows

“…Shock wave/boundary layer interaction is a common phenomenon which occurs in the internal and external flow fields of hypersonic vehicles. Zhang et al (2020) evaluated numerically the influences of the bleed hole diameter, depth, and boundary layer thickness on the bleed mass flow rate of a porous array bleed system in a hypersonic inlet, and explored its potential physical mechanism. Hou et al (2020) investigated self-excited oscillation in an isolator with background waves by means of a wind tunnel experiment.…”