Recent Progress of Hot Jet Aeroacoustics using 3-D Large-Eddy Simulation

Abstract

Improvements in computing speed over the past decade have made Large Eddy Simulation (LES) an attractive tool to study jet noise. In addition, the study of turbulent hot jets for noise prediction is desirable compared to cold/isothermal jets since all jet engines fitted on aircraft operate at hot exhaust conditions. In this regard, we present results for two heated jets with temperature ratios of Tj/T∞ = 1.76 and Tj/T∞ = 2.70, respectively. A computational grid with approximately 4.8 million grid points is used the simulation. Spatial filtering is used as an implicit subgrid scale SGS model in place of the classical Smagorinsky and Dynamic Smagorinsky models. To study the far-field noise, the porous Ffowcs Williams-Hawkings (FWH) surface integral acoustic formulation is employed. The jet development results obtained using our LES methodology are consistent with other LES data and experimental results. The predicted OASPL values for our heated jets follow the trend measured by experiments though our results over-predict by approximately 3dB. Overall, our LES methodology coupled with the Ffowcs Williams-Hawkings aeroacoustics methodology provide satisfactory results.

Numerical Simulation of Supersonic Jet Flows and their Noise

“…In order to investigate the influence of the initial shear layer thickness, two values of θ 0 (0.09r 0 and 0.06r 0 ) are used in this study. The former value has been used by Bodony and Lele 24 and Lew et al 16 and they were able to achieve good agreement with the experiments on turbulent statistics and farfield noise. For laboratory jets, however, the measured value of θ 0 is usually an order of magnitude or more smaller (∼ 2 × 10 −2 r 0 ) 25 compared to that used in LES and DNS of jets.…”

“…Due to limited of computational resources, most of the simulations are performed on the coarse grid unless explicit mentioned. This coarse grid has been used by Lew et al 16,17 to study subsonic hot and isothermal jets with very good results. Figure 1 shows the x-y cross sectional plane of the coarse computational grid.…”

“…Our 3-D LES methodology has demonstrated its success in the prediction of subsonic jet noise. [13][14][15][16][17] However, the ability of our method to predict supersonic jet flows and the related noise fields has not been validated. Therefore, the objective of the current study is to investigate the capability of our 3-D LES methodology for supersonic jet simulations.…”

Matched Hybrid Approaches to Predict Jet Noise by Using Large Eddy Simulation

“…However, roughly 20 points are necessary to correctly discretize this length scale and such a value then leads to huge meshes, even for simple geometries. Thus, a higher ratio of 0.01 -0.05 is usually chosen for LES, as for Bogey et al 4,5 , Lew et al 18 , Bodony et al 3 or Zhao et al…”

Turbulent jet simulation using high-order DG methods for aeroacoustic analysis

“…To date, a number of strategies have been developed to obtain a turbulent flow at nozzle exit. They consist in adding disturbances in the boundary layer inside the nozzle which are either divergence-free "vortex-ring" [7,8,9,10], perturbations based on annular mixing layer linear stability theory [11,12] or a geometrical tripping [13,14,15], in order to force the transition towards a turbulent state. Nonetheless a fine mesh resolution is needed to convect the turbulent fluctuations.…”