Numerical Predictions of the Effect of Rotation on Fluid Flow and Heat Transfer in an Engine-Similar Two-Pass Internal Cooling Channel With Smooth and Ribbed Walls

Abstract

In the present study, a two-pass internal cooling channel with engine-similar cross-sections was investigated numerically. The channel featured a trapezoidal inlet pass, a sharp 180° bend and a nearly rectangular outlet pass. Calculations were conducted for a configuration with smooth walls and walls equipped with 45° skewed ribs (P/e = 10, e/dh = 0.1) at a Reynolds number of Re = 50,000. The present study focused on the effect of rotation on fluid flow and heat transfer. The investigated rotation numbers were Ro = 0.0 and 0.10. The computations were performed by solving the Reynolds-averaged Navier-Stokes equations (RANS method) with the commercial Finite-Volume solver FLUENT using a low-Re k-ω-SST turbulence model. The numerical grids were block-structured hexahedral meshes generated 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 and outlet pass side wall. Heat transfer in the outlet pass was strongly altered by rotation. In contrast to the smooth channel, rotation showed less influence on heat transfer in the ribbed channel. This is due to a strong secondary flow field induced by the 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.

Heat Transfer Augmentation Technologies for Internal Cooling of Turbine Components of Gas Turbine Engines

“…Several other experimental investigations of heat transfer and flow behavior in rotating channels consider effects of channel shape and orientation [169,[248][249][250][251], pin fins [169,251,252], impingement cooling [253], dimpled surfaces [254], arrays of spherical protrusions [255], trailing edge cooling [256][257][258], and rib turbulators [148,149,166,169,259,260]. For example, Tse and Steubner [98] measure different velocity components in a serpentine channel with 45 ∘ ribs.…”

Numerical Calculations on Flow and Heat Transfer in Smooth and Ribbed Two-Pass Square Channels under Rotational Effects

“…They compared the heat transfer characteristics in different rotational number with different rib space. In order to be similar with real blade coolant passage, a modified entrance is added to the channel inlet as in the literature of Huh et al [17] and Schüler et al [18]. In their study, different entrance modifications were made to make the fluid flow close to real engine conditions.…”

combined numerical and experimental study of heat transfer of a turbine airfoil cooling channel with angled ribs and a 180-degree u-bend turn

“…In 2002, L. Al-Hadhrami and J C. Han studied effect of rotation on heat transfer. [4] In 2011, M. Schuler and H.M. Dreher used numerical methods to investigate rotational effect on heat transfer [5] and their results match the experimental results of Taslim et al in 1991. [6] Investigation of different sides of ribbed wall was done by J. Gong, T. Gao and G. Li in 2012.…”

“…Friction factor of test section has two different parts. The first is two legs' friction factor which shown by equation (5). Another factor to estimate flow energy loss is shown by equation 9.…”

“…Mass flow rate of Baseline (Up) and Up-Point (Down) vs P plen and P in Then friction factors can be analyzed by equation(5). Results are shown in the following figures.…”