Reducing Shock Interactions in Transonic Turbine via Three-Dimensional Aerodynamic Shaping

In a high-pressure turbine that is used in combination with a contrarotating low-pressure turbine, the geometry of the low-pressure turbine guide vane gives rise to a shock reflection that has a significant impact on the upstream blade. In consequence, both the performance of the high-pressure turbine and its resistance to high-cycle fatigue failure (i.e., its durability) can be affected. Here, a series of design studies is undertaken in an attempt to mitigate the unsteadiness that arises due to shock interactions in such a turbine. A new method for estimating the forcing function experienced by the high-pressure turbine blade is proposed and evaluated. This method, identified as approximation by surface normal projections, requires only the airfoil geometries and locations as input and demonstrates a significant advantage over an approach to three-dimensional aerodesign consisting exclusively of time-resolved, multirow simulations. The implementation of the approximation by surface normal projections method, in conjunction with a genetic algorithm, is shown to have resulted in superior airfoil geometries with respect to preventing high-cycle fatigue failure and with a reduction of computation time for the analysis of a single airfoil by four orders of magnitude.