Jet Noise Prediction for Chevron Nozzle Flows with Wall-Modeled Large-Eddy Simulations

AMS Seminar Series

Speaker: Gerrit-Daniel Stich, Science and Technology Corporation/NASA Advanced Supercomputing Division
March 25, 2021

Presentation

Seminar Slide Deck (PDF-51MB)

Abstract

Results from ongoing research on jet noise prediction with wall-modeled large-eddy simulations (WMLES) performed with the LAVA computational framework will be presented. In particular the focus of this study is on mixing enhancements from a single stream chevron nozzle at Reynolds number of 1 million. Although the concept of chevron nozzles to reduce jet noise is not new, our understanding of its impact on the overall noise is still not well understood. As a first step towards predicting noise reduction due to mixing enhancement concepts from first principles with WMLES, we simulate the noise generated by a single stream chevron nozzle SMC001 as well as its equivalent axisymmetric round jet nozzle SMC000. Detailed comparisons are made with a dedicated experiment conducted at NASA’s Glenn Research Center and good agreement was achieved. Two different approaches to introduce a turbulent boundary layer were compared but show no major impact on the results. This is especially important given future work where multi-stream nozzles are considered and extended costs of resolving the internal BL would have a bigger cost impact. A permeable Ffowcs Williams Hawkings (FWH) surface enclosing the jet is used to predict far-field noise from the simulated flow-field and excellent comparison to microphone array measurements is achieved within the resolved frequency band. Sensitivity of far-field noise predictions to grid resolution is systematically documented. Near-field comparisons to PIV data shows great agreement for both velocity and normal stresses, however a systematic TKE overshoot at the nozzle exit is seen in the shear-layer. The work shows a cost reduction of an order of magnitude compared to an earlier study of this configuration due to algorithmic and software improvements and demonstrates that WMLES can be used as a cost-competitive approach for jet noise predictions.

Biography

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 Stanford University, Stich joined the Launch Ascent and Vehicle Aerodynamics (LAVA) group in February 2016. Gerrit-Daniel Stich has worked on a wide range of NASA mission related applications and helped push the envelope of simulation technologies for unsteady scale-resolving simulations in support of multiple programs within NASA’s Aeronautics Research Mission Directorate (ARMD). He is one of the developers of LAVA which aims at solving challenging aerodynamics, aeroacoustics and aeroelastic problems with high-fidelity numerical tools. Gerrit-Daniel has supported the development and advancements of hybrid Reynolds-Averaged Navier-Stokes Large-Eddy Simulation (RANS/LES) models as well as the development of wall-modeled LES within the LAVA solver framework. In addition, he has also been part of the team to develop NASA’s first in-house Lattice Boltzmann Method (LBM) solver and applied this method successfully in support of NASA’s Revolutionary Vertical Lift Technology (RVLT) project for the prediction of noise created by Small Scale Unmanned Aerial Vehicles (UAV). He also has been utilizing state-of-the-art WMLES methodologies to contribute NASA’s mission to predict lift at high angles of attack (Clmax) within certification by analysis efforts supported by NASA’s Transformational Tools and Technologies (TTT) project. Gerrit-Daniel’s most recent efforts support NASA’s Commercial Supersonic Technology (CST) project with high fidelity scale-resolving simulation data for the prediction of jet noise from first principles.