Eect of Turbulence Fluctuations on Surface Heating Rate in Hypersonic Turbulent Boundary Layers

In this paper, we investigate the eect of turbulence uctuations on surface heating rate by conducting direct numerical simulations (DNS) of reacting hypersonic turbulent boundary layers at conditions typical of reen-try vehicles. Surface heat uxes, including conductive heat ux and cat-alytic heat ux, are computed and compared for both supercatalytic and noncatalytic walls. At all conditions considered, it is found that turbulence uctuations cause large uctuations in surface heat ux. The instantaneous heat load on the surface can be as large as about 1:7 times the mean value for the condition considered. Turbulence uctuations have subtle in uence on the mean heating rate. We also nd that the eect of turbulence-chemistry interaction on surface heating rate is insignicant at all conditions consid-ered. Nomenclature t time x streamwise coordinate y spanwise coordinate z wall-normal coordinate R ̂ universal gas constant, 8:314, J/(moleK) mixture thermal conductivity, J/(Kms) mixture viscosity, kg/(ms