Analysis of the influence of periodic passing wakes on the secondary flow near the endwall of a linear LPT cascade using DNS and U-RANS

Authors

D. Koschichow - Institut Supérieur de l’Aéronautique et de
J. Fröhlich - Institute of Fluid Mechanics, TU Dresden, Germany
R. Ciorciari - Institute of Jet Propulsion, Universität der Bundeswehr München, Germany
R. Niehuis - Institute of Jet Propulsion, Universität der Bundeswehr München, Germany

Abstract

The paper presents an analysis of the impact of periodically passing wakes on the secondary flow near the endwall in a linear aft-loaded T106 low-pressure turbine cascade. Highly resolved Direct Numerical Simulations (DNS) and unsteady Reynolds Averaged Navier-Stokes (U-RANS) simulations were carried out to capture the transient turbulent motion and periodic components of the flow in detail. The Reynolds number is 90,000 based on the chord length and the exit flow velocity. The evolution of the boundary layers along the endwall are addressed with time-averaged and phase-averaged results. The present paper is one of the first to address this topic by means of DNS. In front of the cascade, both DNS and U-RANS yield very similar results concerning the impact of the incoming wakes on the endwall boundary layer. In the passage, the endwall flow computed with both approaches is different, though. It remains unaffected by the wakes in the DNS while an impact is predicted with U-RANS. Furthermore, the endwall boundary layer exhibits differences in shape factor and turbulent kinetic energy