Flow and noise predictions of the isolated subsonic jets from the Doak Laboratory experiment

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 reduced-order 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

Jet Installation Noise Modelling for Round and Chevron Jets

Wall-Modelled Large Eddy Simulations (LES) are conducted using a 17 high-resolution CABARET method, accelerated on Graphics Process 18 ing Units (GPUs), for a canonical configuration that includes a flat 19 plate within the linear hydrodynamic region of a single-stream jet. This 20 configuration was previously investigated through experiments at the 21 University of Bristol. The simulations investigate jets at acoustic Mach 22 numbers of 0.5 and 0.9, focusing on two types of nozzle geometries: 23 round and chevron nozzles. These nozzles are scaled-down versions (3:1 24 scale) of NASA’s SMC000 and SMC006 nozzles. The parameters from 25 the LES, including flow and noise solutions, are validated by com 26 parison with experimental data. Notably, the mean flow velocity and 27 turbulence distribution are compared with NASA’s PIV measurements. 28 Additionally, the near-field and far-field pressure spectra are evaluated 29 in comparison with data from the Bristol experiments. For far-field 30 noise predictions, a range of techniques are employed, ranging from 31 the Ffowcs Williams-Hawkings (FW-H) method in both permeable and 1 Springer Nature 2021 LATEX template 2 Jet Installation Noise Modelling for Round and Chevron Jets 32 impermeable control surface formulations, to the trailing edge scatter 33 ing model by Lyu and Dowling, which is based on the Amiet trailing 34 edge noise theory. The permeable control surface FW-H solution, incor 35 porating all jet mixing and installation noise sources, is within 2dB of 36 the experimental data across most frequencies and observer angles for 37 all considered jet cases. Moreover, the impermeable control surface FW 38 H solution, accounting for some quadrupole noise contributions, proves 39 adequate for accurate noise spectra predictions across all frequencies 40 at larger observer angles. The implemented edge-scattering model suc 41 cessfully captures the mechanism of low-frequency sound amplification, 42 dominant at low frequencies and high observer angles. Furthermore, this 43 mechanism is shown to be effectively consistent for both M = 0.5 44 and M = 0.9, and for jets from both round and chevron nozzles

Jet flow and noise predictions for the Doak laboratory experiment

Large-eddy simulations (LESs) are performed for two isolated unheated jet flows corresponding to a Doak Laboratory experiment performed at the University of Southampton. The jet speeds studied correspond to acoustic Mach numbers of 0.6 and 0.8 as well as Reynolds numbers based on the nozzle exit diameter of about one million. The LES method is based on the compact accurately boundary-adjusting high-resolution technique (CABARET) and is implemented on graphics processing units (GPUs) to obtain 1000–1100 convective time units for statistical averaging with reasonable run times. In comparison with the previous jet LES calculations with the GPU CABARET method, the mean-flow velocity and turbulent intensity profiles are matched with the hot-wire measurements just downstream of the nozzle exit. The far-field noise spectra of the Doak jets are evaluated using two methods: the Ffowcs Williams–Hawkings approach and a reduced-order implementation of the Goldstein generalized acoustic analogy. The flow and noise results are compared with hot-wire and acoustic microphone measurements of the Doak Laboratory and critically analyzed in comparison with the NASA small hot jet acoustic rig database