Christopher Marks (Committee Member), Rolf Sondergaard (Committee Member), Mitch Wolff (Advisor)
Master of Science in Mechanical Engineering (MSME)
Various approaches have been used to shape the geometry at the junction of the endwall and the blade profile in high-lift low-pressure turbine passages in order to reduce the endwall losses. This thesis will detail the workflow to produce an optimized non-axisymmetric endwall contour design for a front-loaded high-lift research turbine profile. Validation of the workflow was performed and included a baseline planar and test contour case for a future optimization study. Endwall contours were defined using a series of Bezier curves across the passage to create a smooth surface. A parametric based approach was used to develop the test contour shape with a goal of directing incoming endwall flow at the leading edge towards the suction side of the blade. A commercial RANS flow solver was used to model the flow through the passage. The test contour performance was measured in a low-speed linear cascade wind tunnel to verify that the numerical tools adequately captured the necessary endwall flow physics. The numerical model showed excellent agreement of total pressure loss and endwall flow structure compared with experimental measurements. Utilizing the validated workflow, the grid size, mesh deformation method, and commercial RANS flow solver, previously determined to be adequate, were used to optimize the endwall and gave confidence that the optimized contour would perform well experimentally. A genetic algorithm was used to optimize the endwall and to improve the total pressure loss characteristics. Experimental measurements for the final optimized endwall were obtained in the low-speed wind tunnel. Comparisons between the planar endwall, test case endwall, and optimized endwall shapes were made to show how different shapes affect the flowfield. The test case endwall was found to reduce the losses associated with the passage vortex, while the optimized endwall reduced losses associated with the suction side corner separation vortex.
Department or Program
Department of Mechanical and Materials Engineering
Year Degree Awarded
Copyright 2018, all rights reserved. My ETD will be available under the "Fair Use" terms of copyright law.