Evaluating the Immersed Boundary Method in a Ribbed Duct for the Internal Cooling of Turbine Blades

In this paper, immersed boundary method (IBM) is evaluated in a ribbed duct geometry to show the potential of simulating a complex geometry with a simple structured grid. In this framework, instead of resolving the geometry with a body conforming grid, the geometry is immersed into a volume background grid, and the immersed boundary cuts through the background grid and catches the geometry features. A fully developed rib roughed duct geometry is simulated with IBM at a bulk Reynolds number of 1.5 × 104. Three cases have been examined: a stationary case; a case of positive rotation at a rotation number (Ro = ΩDh/U) of 0.3 (destabilizing); and a case of negative rotation at Ro = −0.3 (stabilizing). The dynamic Smagorinsky subgird stress model is used with a second-order central difference discretization. Time averaged mean, turbulent quantities are presented, together with heat transfer. It is found that in general, the simulation with IBM resolves the bulk mean features of the flow with very good accuracy. In the stationary and positive rotation cases, the recirculation patterns and reattachment point predicted by IBM agree very well with the experiment data. In the negative rotation case, prediction of the recirculation zone shows some differences with the experiment. The IBM approach over predicts the turbulent statistics under destabilizing conditions. The overall good agreement between IBM and experimental results suggests that IBM is a promising method to apply to complex blade geometries.Copyright © 2015 by ASME