<p style="text-align: justify">Tip leakage flow is inevitable due to the existence of the tip clearance over &nbsp;rotor blades in turbines. This not only deteriorates blade aerodynamic performance, but also induces severe thermal damage for the tip surface. In order to decrease the tip leakage mass flow rate and improve the tip heat transfer, tip geometry of a transonic turbine cascade is first optimized using a self-developed topology optimization scheme. Subsequently, tip cooling holes are&nbsp;applied and designed&nbsp;over&nbsp;a&nbsp;topology optimized blade tip. Afterwards geometrical positions of tip&nbsp;cooling holes are optimized.&nbsp;Design variable used in the study for optimizing the cooling holes&nbsp;is a material parameter defined at each grid node along the blade camber line. This idea is based on the&nbsp;topology optimization&nbsp;method.&nbsp;The objective&nbsp;of doing so is to minimize energy loss coefficient of the blade cascade and maximize the tip&nbsp;heat transfer intensity. A response surface optimization based on the&nbsp;design of experiment (DOE)&nbsp;analysis is employed, and a multi-objective Genetic Algorithm is used to get Pareto optimum solutions. During the&nbsp;DOE process, in order to reduce computational costs, a CFD method using injection source terms is integrated for numerical simulations. Optimized tip geometries and cooling holes are finally re-constructed.&nbsp;The influence of the new&nbsp;designed tip configuration&nbsp;on blade aero-thermal performance is&nbsp;evaluated via CFD simulations using body-fitted mesh. Results indicate that the optimized tip structure&nbsp;without cooling holes&nbsp;can inhibit tip leakage flow and decreases the blade loss by 5.61% when compared to a flat tip. When tip cooling holes are applied, the tip heat transfer performance is improved while the aerodynamic performance has little change. This positive impact of tip injection on the blade aero-thermal performance&nbsp;can be further improved via adjusting injection mass flow rates.</p>

Multi-Objective Optimization of Turbine Blade Tip With Tip Cooling Holes

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2021/volume/84898

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