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Hybrid RANS/LES Simulation of Jet Surface Interaction Noise

AMS Seminar Series

Speaker: Gerrit-Daniel Stich, Science and Technology Corporation / NASA Advanced Supercomputing Division

Presentation

Seminar Slide Deck (PDF-69.1MB)

Abstract

NASA's Commercial Supersonic Technology (CST) project has formulated a technical challenge to design a quiet propulsion system for a low boom supersonic aircraft that meets Federal Aviation Authority's airport noise regulations with sufficient margin. Several proposed configurations take advantage of shielding from the wing or other air-frame components. Development of carefully validated computational tools are necessary for critically evaluating installation concepts that are currently being proposed to meet the technical challenge. Semi-empirical models that predict the noise reduction potential of arbitrary shielding surfaces are yet to mature. Another key challenge is the systematic assessment of additional noise from the interaction between high speed jet turbulence and a surface in it's vicinity. As a first step towards predicting noise reduction due to radical installation concepts from first principles, we simulate the noise generated by a high speed turbulent round jet near a simple planar surface. Detailed comparisons are made with a dedicated experiment conducted at NASA's Glenn Research Center. Sensitivity of far-field noise predictions to grid resolution is systematically documented. A permeable Ffowcs Williams Hawkings (FWH) surface enclosing both the jet and the shielding surface is used to predict far-field noise from the simulated flow-field. Details of the structured overset grids, numerical discretization, and turbulence model are provided. Near-field comparisons to PIV data and far-field comparisons to microphone array measurements are discussed. Excellent agreement for an initial validation study on an isolated free round jet was obtained and the findings were utilized in the jet surface interaction study. The split between shielded and reflected side of the microphone array was captured with good agreement, as well as the peak in the noise spectra due to scattering of turbulent energy into sound by the trailing edge of the surface.

Biography

Photo of Gerrit-Daniel Stich
Gerrit-Daniel Stich is a research scientist in the Computational Aerosciences Branch of the NASA Advanced Supercomputing Division at NASA Ames Research Center. He has a degree in aeronautics and astronautics from the University of Stuttgart, Germany. After a research year at the Flow Physics and Aeroacoustics Laboratory at the University of Stanford, Stich joined the Launch Ascent and Vehicle Aerodynamics (LAVA) group in February 2016.

Stich has worked on a wide range of NASA mission related applications ranging from high lift prediction on a full scale aircraft during the 3rd High-Lift Prediction Workshop (HLPW3) utilizing Reynolds Averaged Navier-Stokes (RANS) to scale resolving large-eddy simulations (LES) in order to predict noise from propulsion systems such as jets including jet surface interaction noise, aeroacoustic analysis of high-lift devices and noise created by small scale aerial vehicles. Apart from his work in computational fluid dynamics (CFD) utilizing the Navier-Stokes (NS) equations, Stich is also part of the development team focusing on LAVA Lattice-Boltzmann (LB) based flow solver.