Hypersonic Viscous Drag Reduction via Multiporthole Injector Arrays

Abstract

A numerical study has been performed to investigate the film-cooling drag reduction performance of a small-scale multiport injector array, in addition to its potential for improved boundary-layer combustion-induced drag reduction. Hydrogen fuel is injected on a flat plate through an array consisting of four streamwise aligned flush circular portholes into a Mach 4.5 crossflow. Parametric studies were conducted on injectant mass flow rate and streamwise jet-to-jet spacing using the Reynolds-averaged Navier–Stokes equations with Menter’s Shear Stress Transport turbulence model. Complex jet interactions were found in the injection region with a variety of flow features dependent upon the specific configuration. These flow features were found to have subtle effects on the overall system performance. Total viscous drag reductions of up to 60% over a plate length of 0.5 m were achieved, with local drag reductions of over 90% in the near field. Significant wall heat transfer reductions were also found in all cases. Drag reduction and wall heat transfer rates were strongly influenced by injectant mass flow rate, and only moderately effected by streamwise spacing. The maximum drag reduction performance was found for the highest injectant mass flow rate and closest streamwise jet-to-jet spacing. In contrast, mixing performance generally improved with reduced mass flow rate and increased streamwise spacing.