Implementation of non-reflecting boundary conditions in a finite volume unstructured solver for the study of turbine cascades

The analysis of component interaction in the turbomachinery field is nowadays of growing importance. This leads to the combination of different approaches, such as Large Eddy Simulation for combustors and Unsteady Reynolds-Averaged Navier-Stokes equations for turbines, and is responsible for the increase of both computational effort and required accuracy of the numerical tools. To guarantee accurate results and efficient convergence rates, numerical schemes must handle the spurious reflecting waves coming from the boundaries of truncated domains. This can be achieved by means of Non-Reflecting Boundary Conditions. The research activity described in the present paper is aimed at implementing the method of Non-Reflecting Boundary Conditions for the Linearized Euler Equations proposed by Giles in an in-house finite volume implicit time-marching solver. The methodology is validated using the available experimental data obtained at the von Karman Institute for Fluid Dynamics on the LS89 High-Pressure Turbine vane for both subsonic and transonic working condition. The implemented approach demonstrates its importance for the correct evaluation of the pressure distribution both on the vane surface and in the pitchwise direction when the computational domain is truncated at the experimental probe's position.