Design of Fully Cooled Turbine Blade Using Shape and Film Cooling Combined Optimization
DescriptionGas turbines are widely used in power generation and aircraft propulsion. The efficiency of a gas turbine can be improved by increasing the turbine inlet temperature, which now far exceeds the melting temperature of the blade material. Therefore, turbine blades must be protected by cooling, typically by injecting cooler air through hundreds of pores on the blade (fully cooled turbine) to create a protective film over the blade surface. In conventional turbine design, the blade shape and the film cooling system are designed sequentially based on the assumption that cooling flow passively attaches to the blade surface without interfering with the mainstream. Recent studies, especially those in the transonic turbine, showed that the coolant could interact with and change the mainstream, which challenges the fundamental assumption of the sequential design process. Moreover, the sequential design process needs costly interactions between the aerodynamics and heat transfer departments and is susceptible to being trapped in the local optimization. Thus, the concurrent design, which simultaneously optimizes blade shape and film cooling, is proposed to eliminate the interactions between the two departments and achieve global optimization with better aerothermal performance (aerodynamic efficiency and temperature distribution) in the fully cooled turbine blade. Challenges in concurrent optimization of the fully cooled turbine include parameterization (mathematical modelling), mesh generation, and high computational cost. First, based on the PI’s previous work, a parameterization system and a mesh generator ad hoc for the fully cooled turbine will be developed and released to the turbomachinery community as a free software. Second, we will implement our novel algorithm, the multi-scale method, to provide high-fidelity cooling simulations with affordable computational costs using source terms added to the coarse mesh. These methods, looped by the optimizer, lead to concurrent optimization. If our proposed concurrent optimization has substantially better aerothermal performance than the sequential optimization would, a novel direction to improve the efficiency and extend the lifespan of the gas turbine blade will be achieved. The flow physics analysis will be used to quantitatively study the underlying mechanism for the extra gains obtained from the concurrent optimization and provide design guidelines for fully cooled turbine blades. Moreover, the source terms used in the multi-scale method will have several novel applications in cooling-related simulations, for instance, the cooling injection patch using contoured source terms and the machine learning–accelerated computational fluid dynamics simulations using source terms as physics-informed training objectives.
|Effective start/end date
|1/01/24 → …