Published in 49th AIAA Aerospace Sciences Meeting and Exhibit: Orlando, FL, January 4, 2011.
This paper details the results of ongoing efforts to improve upon the meshing techniques required to produce accurate RANS CFD solutions for attached and separated flows for a Circulation Control aircraft. Work, thus far, under the current NASA Research Announcement (NRA) project has revolved around an unstructured near-body volume mesh due to its robustness for complicated geometries. However, it has been found that this technique does a poor job capturing detailed flow features such as the boundary layer, shear layer, and wake of large velocity-gradient regions. Its hindrance is primarily due to the limitations of current computational resources, thus new techniques are investigated to improve the quallty of CFD solutions while not impeding on resources. High quality hybrid near-body volume meshes that combine structured and unstructured meshing have been utilized to meet the goals of the project. The area around the engine and circulation control slots serves as the basis for improved meshing techniques. So far, a hybrid mesh has been successfully generated around the engine and the results of the CFD solutions have improved immensely.
The focus of this paper is to show a comparison of the quality of the CFD solution of old and new meshing techniques. In addition, preilminary results of a hybrid mesh around the circulation control slots are discussed and will be the focus of future work. It has been determined that the primary meshing software used, ICEM CFD does not allow enough user control to adequately refine particular regions in the flow field, thus, alternative meshing software will have to be explored. Current computing resources limit the total size of the mesh to about 35 million. However, given this constraint, the results clearly show that the hybrid mesh attains more refined and stable CFD solutions.
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