Abstract
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 2 t h = 0 . 59 and R e 2 t h = 2 × 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.
Highlights
The trend of high-lift airfoils in modern low-pressure turbines of high-bypass jet engines has led to higher pressure gradients in the blade passages
Steady and unsteady numerical analyses were conducted in order to investigate the effect of periodically incoming wakes on the axial loss development throughout the T106Div-EIZ turbine cascade
T106Div-EIZ produces more intense secondary flows in the passage. This is caused by the higher front-loading, and by the endwall geometry, which influence the roll-up of the incoming endwall boundary layer and the axial loss development in front of the cascade
Summary
The trend of high-lift airfoils in modern low-pressure turbines of high-bypass jet engines has led to higher pressure gradients in the blade passages. The cascades had identical pitch, axial chord, inlet angle, and exit Mach number, but featured different airfoil designs They highlighted the importance of blade loading distribution in regard to loss generation, the maximum velocity location and diffusion on the suction surface. The work presented in this paper combines multiple aspects of the aforementioned works in its investigation of the effects of periodically incoming wakes and blade loading distribution on loss generation in a turbine cascade. In the T106Div-EIZ cascade, the divergent endwalls and the higher front-loading of the blades cause different inflow endwall boundary layer development and stronger secondary flows compared to the parallel endwall case under the same exit flow conditions, which has shown relatively weak secondary flows in previous investigations. The T106Div-EIZ cascade provides a better basis for an analysis of the axial overall and endwall loss development throughout and downstream of the blade passage
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