Spectral characteristics of pitot noise

For experimental studies of transition from laminar to turbulent boundary layer flow it is important to know the ambient noise spectrum in the facility. In supersonic wind tunnels this is often assessed by measuring pitot pressure noise. A discussion of such measurements is given, e. g., by Salyer et al. [1], see also Parziale et al. [2]. The question arises as to whether the noise measured by a pitot tube is a good measure of the free–stream noise. In order to examine this question, we performed a parameter study of the problem by making Euler computations of supersonic flow over a pitot tube when white acoustic noise is introduced at the inflow boundary.