Three statistical jet noise prediction models are compared for a representative set of single-stream jet cases, which include cold and hot jets of the Strategic Investment in Lowcarbon Engine Technology (SILOET) experiment at acoustic Mach number 0.875 and the cold jets of the NASA Small Hot Jet Acoustic Rig (SHJAR) experiment at acoustic Mach numbers 0.5 and 0.9. The implemented models are those proposed by Tam and Auriault, Khavaran, and the Goldstein Generalised Acoustic Analogy (GAA). By the virtue of reduced-order modelling, which is based on the single-point meanflow and turbulence statistics, all these implementations use a number of empirical dimensionless source parameters for far-field noise spectra predictions. In comparison with the Tam and Auriault model, the Khavaran and GAA model implementations use several dimensionless parameters, which are available from the previous literature and assumed to be more-or-less universal for a class of single-stream jets. These parameters include the fluctuating enthalpy function and the dimensionless amplitudes of auto-covariances of turbulent fluctuating stresses and velocities available from the literature. The comparison of the three models is aimed not only at assessing their accuracy for a range of jet conditions, observer angles, and frequencies, but also to examine their robustness outside of a reference jet experiment for which their source models were calibrated. For the input to each model, the meanflow, turbulence kinetic energy, and dissipation rate extracted from Large Eddy Simulations
Flow and noise solutions using Large Eddy Simulation (LES) are evaluated for two jets at acoustic Mach numbers 0.6 and 0.8. The jets correspond to Doak Laboratory Experiment performed at the University of Southampton. LES method is based on the Compact Accurately Boundary-Adjusting High-Resolution Technique (CABARET) scheme and is implemented on Graphics Processing Units. In comparison with many other jet noise benchmarks, the Doak jet cases include well-defined boundary conditions corresponding to the meanflow velocity and turbulent intensity profiles measured just downstream of the nozzle exit. The far-field noise predictions are obtained using two approaches. First, the LES solutions are coupled with the penetrable surface formation of the Ffowcs Williams-Hawkings method. The second approach is based on the reducedorder implementation of the Generalised Acoustic Analogy model for which time averaged quantities are obtained from the LES solutions. All numerical solutions are compared with the flow and acoustic microphone measurements from the Doak experiment. The results are cross-validated using the sJet code, which corresponds to an empirical model obtained from interpolations over a large set of NASA jet noise data.
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