Validating a Monotonically-Integrated Large Eddy Simulation Code for Subsonic Jet Acoustics

Abstract

The results of subsonic jet validation cases for the Naval Research Lab's Jet Engine Noise REduction (JENRE) code are reported. Two set points from the Tanna matrix, set point 3 (Ma = 0.5, unheated) and set point 7 (Ma = 0.9, unheated) are attempted on three different meshes. After a brief discussion of the JENRE code and the meshes constructed for this work, the turbulent statistics for the axial velocity are presented and compared to experimental data, with favorable results. Preliminary simulations for set point 23 (Ma = 0.5, Tj/T∞ = 1.764) on one of the meshes are also described. Finally, the proposed configuration for the farfield noise prediction with JENRE's Ffowcs-Williams Hawking solver are detailed. Nomenclature x, y, zCartesian coordinates, with origin at the nozzle exit and centerline, x indicating the axial coordinate, increasing downstream r Radial coordinate, r 2 = y 2 + z 2 ∆ Approximate mesh spacing L Length of the mesh region meant to resolve the turbulent nearfield D j Exit diameter of the nozzle U j Fully-expanded jet exit velocity U , U Mean and root-mean square of axial velocity, respectively T j Fully-expanded jet exit temperature T , T Mean and root-mean square of temperature, respectively T 0 , T Startup and statistics-gathering simulation times, respectively θ Polar angle, with θ = 0 pointing upstream (i.e. the negative-x direction) y τ Estimate of viscous length scale in the nozzle boundary layer

Assessment of artificial fluid properties for high-order accurate large-eddy simulations of shock-free compressible turbulent flows with strong temperature gradients

“…In this section, we study a spatially developing round jet configuration having different jet-to-ambient temperature ratios corresponding to the experiments by Bridges and Wernet (BW-Exp) [39]. This experimental dataset has been used for the assessment of LES results by many groups [57,58,59,60]. In addition, a similar configuration comprising of a stronger temperature ratio, representative of typical reacting flows (e.g.…”

CABARET solutions on graphics processing units for NASA jets: Grid sensitivity and unsteady inflow condition effect

“…For example, [8] and [19] showed that the difference between applying the realistic unsteady inflow condition and the simple initial laminar inflow condition could be very large (O(5dB) in terms of the far-field noise spectra) for the jet flows they considered. On the other hand, for other high-speed jet flows such as considered by [7] or in case of [13] and [14], who considered the same SMC000 nozzle geometry as in the current article, there were laminar inflow conditions used which didn't lead to a drastic deterioration of the solution accuracy compared to the experiment either in terms of the far-field noise spectra or noise-sensitive jet flow properties such as the fourth-order velocity correlations.…”

“…The flow conditions inside the nozzle were not recorded and the experimental data available include the flow Particle Image Velocimetry (PIV) and the far-field microphone measurement data. Thanks to the availability of both the flow data and the far-field acoustic measurement, the SHJAR database has already attracted attention for validation of LES methods [12][13][14] as well as hybrid Rynolds Averaged Navier Stokes (RANS)-LES approaches [15][16][17].…”

Jet Flow and Noise Predictions for the Doak Laboratory Experiment

“…There are relatively few high-quality jet noise databases, where both the flow data and the far-field acoustic measurements are available. One of them, the so-called SHJAR (Small Hot Jet Acoustic Rig) [12,13] at NASA has attracted significant attention for validation of LES methods [14][15][16][17] as well as hybrid Reynolds Averaged Navier-Stokes (RANS)-LES approaches [18][19][20][21]. In addition to conventional fixed-grid Navier-Stokes methods, alternative unsteady Computational Fluid Dynamics (CFD) methods of particle-in-cell type such as Lattice Boltzmann (LBM) were tested and showed their computational efficiency for flow and noise predictions for the NASA jet noise problems [22,23].…”