Scaling of noise from heated subsonic jets with properties from RANS CFD

V. H. P. d. Rosa¹; R. H. Self¹; C. R. S. Ilário²

¹ ISVR, University of Southampton, Southampton, UK; ² Embraer, São José dos Campos, Brazil

doi:10.20906/CPS/COB-2015-0273

Resumo

Scaling laws traditionally use global information about the jet such as exit velocity and temperature; in this paper a scaling law that takes input from a numerical RANS solution is presented. By using Lighthill acoustic analogy, the sources of jet mixing noise are split in two components related to (i) Reynolds stresses and (ii) entropy fluctuations. The contribution of each component to the overall sound pressure level (OASPL) is computed for subsonic single-stream jets at different exit velocities and temperatures, and results are compared with experimental data. Moreover, the OASPL results are used to compute the noise spectrum by shifting two experimental master spectra. The results agree well with experiments for observer angles close to 90 degrees for all cases, confirming the need to consider the entropy term for heated subsonic jets and how it scales with the logarithm of the local temperature gradient. This study is a step towards the development of a RANS-based model to predict the contribution of entropy fluctuations to the total jet mixing noise.

Palavras-chave: jet noise; Lighthill equation; RANS CFD; scaling law