In modern low pressure turbines the efforts to increase aerodynamic blade loading by increasing blade pitch and optimizing midspan performance in order to reduce weight and complexity can produce increased losses in the endwall region. Airfoils of high flow turning and high pressure gradients between the blades generate strong secondary flows which impair the global aerodynamic performance of the blades. In addition, the unsteady incoming wakes take influence on transition phenomena on the blade surfaces and the inlet boundary layer, and consequently affect the development and the evolution of the secondary flows. In this paper, the T106 cascade is used to identify the effect of unsteady wakes on the development of secondary flows in a turbine cascade. Numerical and experimental results are compared at different flux coefficients and Strouhal numbers, the relative differences and similarities are analyzed.

Secondary flow and loss development in the T106Div-EIZ low-pressure turbine cascade are investigated utilizing (U)RANS simulations in cases with and without periodically incoming wakes at $M{a}_{2th}=0.59$ and $R{e}_{2th}=2\times {10}^5$ . The predictions are compared to experimental data presented by Kirik and Niehuis (2015). The axial mid-span and overall loss development in the T106Div-EIZ and the T106A-EIZ in the steady case are analyzed regarding the effects caused by the different loading distributions and by the divergent endwall geometry. Furthermore, the entropy generation is analyzed in the T106Div-EIZ with periodically incoming wakes in several axial positions of interest and compared to the undisturbed steady case. It is found that in the front-loaded T106Div-EIZ, the incoming wakes cause a premature endwall loss production in the front part of the passage, resulting in a lower intensity of the secondary flow downstream of the passage and a redistribution of the loss generation components.