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Hybrid reynolds-averaged/large eddy simulation of a cavity flameholder; assessment of modeling sensitivities
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Baurle, R. A. |
| Copyright Year | 2015 |
| Description | Steady-state and scale-resolving simulations have been performed for flow in and around a model scramjet combustor flameholder. The cases simulated corresponded to those used to examine this flowfield experimentally using particle image velocimetry. A variety of turbulence models were used for the steady-state Reynolds-averaged simulations which included both linear and non-linear eddy viscosity models. The scale-resolving simulations used a hybrid Reynolds-averaged / large eddy simulation strategy that is designed to be a large eddy simulation everywhere except in the inner portion (log layer and below) of the boundary layer. Hence, this formulation can be regarded as a wall-modeled large eddy simulation. This effort was undertaken to formally assess the performance of the hybrid Reynolds-averaged / large eddy simulation modeling approach in a flowfield of interest to the scramjet research community. The numerical errors were quantified for both the steady-state and scale-resolving simulations prior to making any claims of predictive accuracy relative to the measurements. The steady-state Reynolds-averaged results showed a high degree of variability when comparing the predictions obtained from each turbulence model, with the non-linear eddy viscosity model (an explicit algebraic stress model) providing the most accurate prediction of the measured values. The hybrid Reynolds-averaged/large eddy simulation results were carefully scrutinized to ensure that even the coarsest grid had an acceptable level of resolution for large eddy simulation, and that the time-averaged statistics were acceptably accurate. The autocorrelation and its Fourier transform were the primary tools used for this assessment. The statistics extracted from the hybrid simulation strategy proved to be more accurate than the Reynolds-averaged results obtained using the linear eddy viscosity models. However, there was no predictive improvement noted over the results obtained from the explicit Reynolds stress model. Fortunately, the numerical error assessment at most of the axial stations used to compare with measurements clearly indicated that the scale-resolving simulations were improving (i.e. approaching the measured values) as the grid was refined. Hence, unlike a Reynolds-averaged simulation, the hybrid approach provides a mechanism to the end-user for reducing model-form errors. |
| File Size | 3588955 |
| Page Count | 26 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20150006033 |
| Archival Resource Key | ark:/13960/t0sr3w77x |
| Language | English |
| Publisher Date | 2015-01-05 |
| Access Restriction | Open |
| Subject Keyword | Aircraft Propulsion And Power Numerical Analysis Fluid Mechanics And Thermodynamics Von Karman Equation Fourier Transformation Sensitivity Analysis Power Spectra Computational Fluid Dynamics Supersonic Combustion Ramjet Engines Scale Effect Velocity Distribution Assessments Steady State Environment Simulation Flame Holders Reynolds Stress Errors Cavities Large Eddy Simulation Reynolds Averaging Flow Velocity Dynamic Models Pressure Measurement Computational Grids Combustion Chambers Mach Number Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
