Aerodynamic optimization of an impulse turbine rotor cascade is described in this paper. The aim of the optimization is to minimize the total pressure losses through the cascade by reshaping the turbine airfoil. For a more realistic calculation of the boundary layer and the associated losses, laminar/turbulent transition is computed by means of the commercial CFD code Fluent. The solver underwent an accurate validation before it is inserted into the optimization loop. A proper optimization procedure is developed which is based on a sequential use of two modules: first, a global search is performed using a genetic algorithm, then a local optimization is carried out by means of a Sequential Quadratic Programming (SQP) algorithm. The benefits of this approach are demonstrated, in that the total pressure coefficient of the cascade can be lowered up to 25%.
On the development of methods of the laminar-turbulent transition prediction
