A Numerical Study of Fluid Flow Around Two-Dimensional Lifting Surfaces.
MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF MECHANICAL ENGINEERING
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There are always differences between theoretical and experimental results in the study of lifting surfaces. Bounding box control volume measurements infrequently yield exact conservation of mass or consistent values for lift and drag coefficients. Numerically calculated wakes often differ from experimental data. Quite often, an empirical correction can be applied to fit theory to experiment to account for these differences. However, as the demands for state of the art foil design increase, fluid dynamicists are pressed to look carefully at these inconsistencies in order to improve current design and analysis methods. Using a Reynolds Averaged Navier Stokes RANS computer code and a highly refined fluid mesh, one can begin to explore the subtle characteristics of the fluid flow in the entire domain and the details of certain key regions around a foil. Specific areas of great interest are flow around the trailing edge, flow within the boundary layer, wake profiles and the influence of tunnel wall boundaries in experimental facilities. The overall goal of this thesis is to resolve some of the discrepancies between theoretical results and experimental data. A computer code has been developed to generate the geometry for the fluid flow domain surrounding an arbitrary foil shape at a specified angle of attack in the MIT Marine Hydrodynamics Laboratory MHL water tunnel. This geometry is provided as input data for the RANS solver. A suite of software tools are developed to provide post processing analysis to compare the RANS solution with other numerical techniques and experimental measurements. Through the use of case studies, the numerical results of the RANS code are compared with recent MHL experimental data and other computational tools. A comparison is made between the experimental and RANS code results using a control volume analysis.
- Fluid Mechanics