Prediction of jet Mach and Reynolds numbers from acoustic measurements

* Presenting author
Day / Time: 21.03.2018, 09:20-09:40
Room: MW 1050
Typ: Regulärer Vortrag
Abstract: We study the noise generation mechanisms in a turbulent and compressible jet and how the jet noise is affected by changes in the main parameters. The objectives of this part of the study are to (i) establish a relationship between the parameters of the fluid mechanics with the properties of the acoustics in order to (ii) predict the Mach and the Reynolds numbers of turbulent and compressible jets from acoustic measurements. We compare the jet noise from numerical simulations with laboratory experiments and field work experiments of more than 15 000 volcanic jets at Mount Etna and Stromboli volcanoes. Using correlations from the literature, we confirmed that the peak Strouhal number of the Turbulent Mixing Noise component increases with larger Reynolds numbers. Moreover, we found the relationship between the peak Helmholtz number of the Broadband Shock Noise with the fully expanded Mach number. We applied existing correlations from the literature to own numerical and experimental results and we reproduced the same behavior when changing the Reynolds number and found the effect of the Mach number in the jet noise. This is especially useful when no direct access to the jet flow is possible, as in volcanic flows.