Numerical Prediction of Noise from Round and Beveled Nozzles

Numerical simulations of the flow field and the noise generated by round and beveled nozzles are carried out. The objective of this study is to gain insights into the flow characteristics that yield a noise reduction for the beveled nozzle. For aircraft applications, the geometry of the nozzles must be optimized both for aerodynamic and acoustic performance. Results from both RANS and LES computations are presented. The aerodynamic predictions from RANS are in very good agreement with experimental measurements. The noise predictions from LES agree with the trends observed in the measurements. Given the complexity of the problem and the extreme grid requirements, good spectral predictions are obtained, albeit with a strict limit on the maximum Strouhal number. For the subsonic jets, the noise is consistently under-predicted close to the jet direction. The results are encouraging and this study is a part of on-going efforts to better understand the flow physics, and possibly derive fresh ideas from a broad visibility of the turbulence.