Acoustic and velocity field over 3D cavities

Effects of wall mounted cavity on a Mach 1.7 freestream flow over it are investigated experimentally and numerically. Three different three dimensional （3D） cavity configurations have been used in the study. The results are compared with those of a two dimensional （2D） cavity. Flow field over the cavity is observed to depend intensely on the cavity width and on the allied aerodynamic flow structure in the vicinity of the cavity. Pressure oscillations generated by presence of wall mounted cavity in supersonic freestream was also observed to affect the fluid motion over cavities. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi：10.1063/2.1301201]

Supersonic Cavity Flows over Concave and Convex Walls

Supersonic cavity flows are characterized by compression and expansion waves, shear layer, and oscillations inside the cavity. For decades, investigations into cavity flows have been conducted, mostly with flows at zero pressure gradient entering the cavity in straight walls. Since cavity flows on curved walls exert centrifugal force, the features of these flows are likely to differ from those of straight wall flows. The aim of the present work is to study the flow physics of a cavity that is cut out on a curved wall. Steady and unsteady numerical simulations were carried out for supersonic flow through curved channels over the cavity with L/H = 1. A straight channel flow was also analyzed which serves as the base model. The velocity gradient along the width of the channel was observed to increase with increasing the channel curvature for both concave and convex channels. The pressure on the cavity floor increases with the increase in channel curvature for concave channels and decreases for convex channels. Moreover, unsteady flow characteristics are more dependent on channel curvature under supersonic free stream conditions.

Supersonic Cavity Based Combustion with Kerosene/Hydrogen Fuel

A comparative study with kerosene and hydrogen fuel in a model scramjet combustor has been carried out numerically. The effect of fuel-air equivalence ratio on the flow field properties in a cavity based mixing mechanism at a freestream Mach number of 2.08 has been probed. The investigation has been carried out in a two dimensional numerical model where a cavity of length to depth ratio of 2 is mounted on one of the walls of the flow channel. The flow field shock structure is observed to change with the change in fuel-air equivalence ratio. Total pressure loss is observed to depend both on fuel air equivalence ratio and the fuel type. The spread of fuel in the test section shows marked variation with the equivalence ratio. Performance of injector location on the fuel-air mixing is also probed during the course of the investigation.