Understanding of losses caused by unsteady effects is essential in efforts to improve the efficiency of modern turbomachines. In the present research work, the unsteady midspan flow in a typical high pressure axial turbine was investigated using a compressible Navier Stokes solver. The aim of this study was to take a closer look at trends in the loss behavior depending on several flow and geometry parameters as well as to give a physical explanation of these trends. Two different definitions of loss coefficients were also employed for the loss assessment and its suitability for evaluation of “unsteady losses” was discussed considering accuracy and physical aspects.
