Temperature Effect

Since the luminescent intensity of PSP is intrinsically temperature-dependent, a temperature change on a model during a wind tunnel run results in a significant bias error in PSP measurements if the temperature effect is not corrected. In addition, temperature influences the total uncertainty of PSP measurements through the sensitivity coefficients of the variables in the error propagation equation. Hence, the surface temperature on a model must be known in order to correct the temperature effect of PSP. In general, the surface temperature distribution can be measured experimentally using TSP or IR camera and determined numerically by solving the motion and energy equations of flows coupled with the heat conduction equation for a model. For a compressible boundary layer on an adiabatic wall, the adiabatic wall temperature Taw can be estimated using a simple relation

TaJT0 = [1 + r( y – 1)M2 /2][1 + (y-1)M2/2]-1, where r is the recovery factor for the boundary layer, T0 is the total temperature, M is the local Mach number, and у is the specific heat ratio.