Investigation of film cooling on nose cone by a forward facing array of micro-jets in Hypersonic flow

A numerical study has been performed to investigate the film-cooling heat reduction performance of a single jet (diameter 2 mm and 0.9 mm), and an array forward facing of micro-jets (diameter 300 pm each) of the same effective area (corresponding to the respective single jet). Helium and/or Nitrogen are injected as coolant gases from the tip of the nose through an array of micro into a Mach 5.9 counterflow free stream. Parametric studies were conducted on injection total pressure with various diameters by 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 depending upon the specific configuration. These flow features were found to have subtle effects on the overall system performance. Total heat load reductions of up to 40% over a nose were achieved for micro jet with low Pressure Ratio. Significant wall heat transfer reductions were also found in all cases. The heat transfer rates were strongly influenced by injection mass flow rate, and only moderately affected by the number of micro jets. The maximum heat reduction performance was found in the highest injection total jet pressure (consequently more mass flow rate) with the highest micro array. (C) 2015 Elsevier Ltd. All rights reserved.