Simulation of Roughness Effects on Hypersonic Blunt Body Entry Heating
Start Date
2-3-2011 4:35 PM
Description
The objective of the current work is to improve Computational Fluid Dynamics (CFD) prediction of turbulent heating in the presence of distributed surface roughness. Typically, distributed surface roughness is encountered in earth or planetary entry of spacecraft with ablative heat shields. The current approach is based on the use of a combination of CFD analysis and experimental observations to improve the turbulence modeling needed to predict the effects of roughness on turbulent surface heating. Several experiments are used to guide as well as validate proposed modification to the commonly used Baldwin-Lomax turbulence model to improve its prediction of heat transfer in the presence of surface roughness. Specifically, the current work describes two different modifications to the inner layer of the Baldwin-Lomax model. The modifications are implemented in the DPLR code but could be easily utilized in any CFD code that uses the Baldwin-Lomax model. The proposed modifications are consistent with similar modifications developed earlier to treat surface mass injection. This has the potential to eventually develop a model capable of treating combined roughness and surface blowing. Heat transfer data obtained from both the original and modified roughness models are compared with several heat transfer data obtained from available experiments with surface roughness corresponding to values encountered during flight conditions. The results clearly show that the proposed modification produce a much better prediction of the heating augmentation due to surface roughness.
Simulation of Roughness Effects on Hypersonic Blunt Body Entry Heating
The objective of the current work is to improve Computational Fluid Dynamics (CFD) prediction of turbulent heating in the presence of distributed surface roughness. Typically, distributed surface roughness is encountered in earth or planetary entry of spacecraft with ablative heat shields. The current approach is based on the use of a combination of CFD analysis and experimental observations to improve the turbulence modeling needed to predict the effects of roughness on turbulent surface heating. Several experiments are used to guide as well as validate proposed modification to the commonly used Baldwin-Lomax turbulence model to improve its prediction of heat transfer in the presence of surface roughness. Specifically, the current work describes two different modifications to the inner layer of the Baldwin-Lomax model. The modifications are implemented in the DPLR code but could be easily utilized in any CFD code that uses the Baldwin-Lomax model. The proposed modifications are consistent with similar modifications developed earlier to treat surface mass injection. This has the potential to eventually develop a model capable of treating combined roughness and surface blowing. Heat transfer data obtained from both the original and modified roughness models are compared with several heat transfer data obtained from available experiments with surface roughness corresponding to values encountered during flight conditions. The results clearly show that the proposed modification produce a much better prediction of the heating augmentation due to surface roughness.