Density fluctuations measurement by rayleigh scattering using a single photomultiplier

Rayleigh scattering provides a direct nonintrusive method for density measurement, which is of particular interest in aeroacoustics. However, two major concerns arise linked to the use of photomultipliers. First, the detection of photon flux is corrupted by the presence of dust particles in the flow. An original signal processing is proposed in this study to remove their signatures. Second, the random arrival of photons on a photomultiplier induces shot noise, which can be partly removed by using two photomultipliers. It is shown in this study that a single photomultiplier combined with suitable processing can also be used to remove shot noise. Both approaches are compared for the case of a compressible subsonic jet exhausting in an anechoic wind tunnel. © Copyright 2017 by the authors.