Large-Eddy Simulations of a Supersonic Heated Jet

Abstract

Large-eddy simulations of imperfectly expanded jet flows from a convergent-divergent nozzle with a heated (600K) and a cold jet conditions have been carried out. Mach wave radiation is present outside the jet core and the heated jet shows a much larger density shear-layer spreading than the cold jet. The potential core length is shortened, but the shock-cell shape and shock-cell spacing remain similar to those shown in the cold jet. It is found that the Crocco-Busemann equation captures well the correlation between the temperature and the axial velocity in the cold jet, but it underestimates the nonlinear variations in the shock-containing region in the heated jet. Temperature effect has more impact on the high-frequency components of pressure fluctuations near the nozzle exit, but the impact moves to lowand mid-frequency ranges further downstream. The convection speed of the near-field pressure waves increases with the temperature. The addition of inflow random pressure perturbations increases the velocity shear-layer spreading and turbulence intensities near the nozzle exit, but it reduces the screech intensity and the peak intensity of the overall pressure fluctuation level. The heated jet is found to be more sensitive to the inflow pressure perturbations than the cold jet.