Aerothermal Optimization of Fully Cooled Turbine Blade Tips

Abstract

Optimal turbine blade tip designs have the potential to enhance aerodynamic performance while reducing the thermal loads on one of the most vulnerable parts of the gas turbine. This paper describes a novel strategy to perform a multi-objective optimization of the tip geometry of a cooled turbine blade. The parameterization strategy generates arbitrary rim shapes around the coolant holes on the blade tip. The tip geometry performance is assessed using steady Reynolds-Averaged Navier-Stokes simulations with the k-ω SST model for the turbulence closure. The fluid domain is discretized with hexahedral elements, and the entire optimization is performed using identical mesh characteristics in all simulations. This is done to ensure an adequate comparison among all investigated designs. Isothermal walls were imposed at engine-representative levels to compute the convective heat flux for each case. The optimization objectives were a reduction in heat load and an increase in turbine row efficiency. The multi-objective optimization is performed using a differential evolution strategy. Improvements were achieved in both the aerodynamic efficiency and heat load reduction, relative to a conventional squealer tip arrangement. Furthermore, this work demonstrates that the inclusion of over-tip coolant flows impacts the over-tip flow field, and that the rim-coolant interaction can be used to create a synergistic performance enhancement.

Exploring Topology Optimisation of High Pressure Turbine Blade Tips

“…As shown by Caloni et al [11], blade tips which combine common designs like winglet and squealer shapes with different openings can bring efficiency benefit without increase in heat load. Andreoli et al [14] showed that creating a topology free optimisation of squealer tips has a great potential in exploring different squealer topologies in single optimisation workflow. Therefore, in this work, different optimisations are carried out, gradually exploring a design space to create the novel topology free turbine tip optimisation.…”

“…Comparing the squealer and carved design, authors state that squealer tips are superior to carved designs, offering larger reduction in the heat load for the price of smaller aerodynamic efficiency drop. Andreoli et al [14] did a multi-objective optimisation of turbine tips with film cooling. They parametrized geometry using mapping of the Bezier surface in non-dimensional plane which represented the blade tip.…”

Loss classification and review of secondary flow models in gas turbine cascades

“…Для уменьшения потерь вследствие утечек в радиальном зазоре применяют как активные, так и пассивные методы. Большинство опубликованных в открытых источниках методов являются пассивными и заключаются в геометрическом воздействии на структуру течения в области радиального зазора рабочей решетки ТВД: бандажирование лопаток [28][29][30], применение истираемых покрытий, применение различных форм уплотнений торцов рабочих лопаток [31] и др. Среди пассивных методов: гидростатический (например, наддув радиального зазора [32]), тепловой, механический и комбинированный.…”

Effects of Partial Suction Side Rim on the Aerodynamics and Heat Transfer Cooling Performance of the Turbine Blade Squealer Tip

“…The results stated that removing the pressure side rim at the trailing edge could improve the tip cooling efficiency near the trailing edge. Andreoli et al [12] carried out the multiobjective optimization of the squealer tip rim profile. The optimized blade tip heat flux dropped by 65% and the aerodynamics efficiency increased by 0.65%.…”