Effects of Temperature and Heat Transfer on Shock Train Structures inside Constant-Area Isolators

Abstract

Effects of temperature and heat transfer on shock train structures and isolator performance were investigated both experimentally and numerically. Two heat-sink isolators, one with a rectangular configuration and one with a round configuration, with identical cross-sectional areas and a length of 25, were operated with Mach 1.8 and 2.2 flows. Pressure profiles inside the shock train and temperatures on the isolator walls were measured. It was found that heat addition to a low Mach number flow inside an isolator can choke the flow and potentially decrease the isolator performance. On the other hand, heat removal from the flow can enhance the isolator performance by retarding flow choking. The numerical analysis shows that heat addition to a supersonic flow can increase boundary layer thickness and decrease both flow Mach number and the amount of heat required to choke the flow. Shock trains generated in a high-temperature flow are relatively long, and therefore may require a long isolator to prevent engine unstart. NOMENCLATURE H = isolator duct height L0.8 = shock train length M = Mach number P = pressure PR = pressure ration across the isolator, Pb/P1 T = temperature t = time u = freestream velocity x = freestream direction xs = shock train leading edge y = transverse direction z = spanwise direction γ = specific heat ratio θ = boundary layer momentum thickness Superscript