Shape Optimization of a Low Pressure Turbine Cascade Endwall Using a Genetic Algorithm
Technical Report,01 May 2017,01 Oct 2019
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH WRIGHT-PATTERSON AFB United States
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Various approaches have been used to shape the endwall and blade profile in order to reduce the endwall losses in turbine passages. This study describes the workflow used to design an optimized endwall contour for a front-loaded high-lift low pressure turbine research profile. Endwall contours were defined using a series of Bezier curves across the passage to create a smooth contoured surface. A new computational mesh was generated for each design configuration by morphing the baseline mesh of a passage with a flat endwall until it matched each new contour shape. Two different contour designs were fabricated and installed in a low speed linear cascade wind tunnel to validate the workflow. One contour shape was designed using approaches described in open literature. The second shape was optimized using a genetic algorithm using passage total pressure loss as the objective function. The optimization process produced a unique and aggressive contour shape. Comparisons between the planar and the contoured endwall shapes are presented both experimentally and computationally. Although the two different contours produced a similar reduction in passage loss, the analysis shows that the effect of the two contours on the endwall flow field are significantly different providing insight into the fluid dynamic mechanism responsible for the reduction in endwall losses.
- Jet and Gas Turbine Engines
- Fluid Mechanics