Numerical Predictions of Fluid Flow and Heat Transfer in a Rotating Engine-Similar Two-Pass Internal Cooling Channel With Smooth and Ribbed Walls

Kurzfassung

Numerical investigations of a two-pass internal cooling channel with engine-similar cross-sections were conducted. The channel featured a trapezoidal inlet pass, a sharp 180° bend, and a nearly rectangular second pass. Calculations were conducted for a smooth and a ribbed channel (α = 45°, P/e = 10, e/dh=0.1) at Re = 50,000 and four different rotation numbers Ro = 0, 0.02, 0.05 and 0.1. The Reynolds-averaged Navier-Stokes (RANS) equations were solved by the DLR Research Code TRACE developed at Institute of Propulsion Technology of German Aerospace Centre Cologne. A Wilcox k-ω turbulence model with additional modifications for rotating flows and stagnation point behaviour was applied. Computations were performed using block-structured grids created with POINTWISE. Flow field measurements were independently performed at DLR using Particle Image Velocimetry. In the smooth channel, rotation had a large impact on secondary flows. Especially, rotation induced vortices completely changed the flow field. Rotation also changed flow impingement on tip wall and outlet pass side wall. Heat transfer in the outlet pass was strongly altered by the influence of rotation. In contrast to the smooth channel, rotation showed less influence on heat transfer in the ribbed channel. This was due to a strong secondary flow field induced by ribs. However, in the outlet pass Coriolis force markedly affected the rib induced secondary flow field. The influence of rotation on heat transfer was visible in particular in the bend region and in the second pass directly downstream of the bend.