Design of non-axisymmetric endwall of a stator to improve the efficiency of a high pressure turbine: A pseudo objective function

This paper presents an optimization method to improve the efficiency of a high pressure turbine by constructing non-axisymmetric endwalls on the hub and the shroud of the stator of a high pressure turbine. The numerical investigation was conducted through commercial tool Fine^TM/Turbo. The optimization was quantified by using optimization algorithms based on the pseudo-objective function. The objective was to increase total-to-total efficiency with the constraint on the mass flow rate equal to the design point value. In order to ensure that global optimum had been achieved, the function of parameters was first approximated through the artificial neural network, and then optimum was achieved by implementing the genetic algorithm. It was adopted through the design and optimization environment of Fine^TM/Design3D. The endwall of the hub and the endwall of the shroud of the stator were optimized together. The result of the investigation showed that the optimized shape of the endwalls can significantly help to reduce the transverse pressure gradient. The total pressure loss coefficient and spanwise mass averaged entropy were reduced. The design of the optimized turbine under steady simulations was confirmed through unsteady simulations.