Wall pressure fluctuations induced by a compressible coaxial jet in installed configuration

In this paper wall pressure fluctuations induced by a subsonic coaxial jet grazing a wing have been experimentally investigated. The wall pressure signature on the wing was characterised in both static and flight conditions. This study is part of a broader research activity that has been carried out during the Collaborative European project JERONIMO (ACP2-GA-2012-314692) funded under the 7th Framework Programme. Measurements presented therein have been performed in the CEPRA 19 large-scale wind tunnel facility where an instrumented scaled wing model was installed close to a coaxial compressible jet. The pressure field on the wing was measured by flush-mounted pressure transducers installed on the pressure side. Experiments were carried out with the coaxial jet operating in single-stream-like jet conditions, i.e. with same flow conditions for the primary and secondary jets, at two different Mach numbers Mj=0.6 and Mj=0.75. Flight effect was explored for the jet flow condition Mj=0.75, with the flight-stream Mach number Mf set equal to 0.18. Data were analysed in time and frequency domains and particular attention was devoted to determine universal scalings of the spectral quantities. Semi-empirical models commonly used in canonical turbulent boundary layers to reproduce the wall pressure coherence are tested and verified for both the static and flight conditions.