On the optimization of 3D-flow and heat transfer by using the Ice Formation Method: Vane endwall heat transfer

• Application of IFM to vane/endwall junction yields ice-contoured endwalls.
• Created contours reduce heat transfer compared to flat endwall.
• Heat transfer reductions result from weakening of vortex system and secondary flows.
• Heat transfer closely linked to entropy production rates due to heat conduction.

Technical flow devices are usually optimized by using numerical algorithms that analyze a multitude of design variants for the flow restraining geometry until an optimum solution is found. In this paper, we present an alternative approach: the Ice Formation Method (IFM). We show the application of this method to a turbine vane endwall in order to optimize the endwall with respect to heat transfer. On the basis of a flat endwall, we first created ice-contoured endwalls in our water channel test facility. We then analyzed these contours using numerical simulations with air to approve them for the working medium of gas turbines. Results show that the IFM reliably creates contours with reduced heat transfer coefficients (HTC). In this vein, we created one contour that reduces the average HTC by 5.2% compared to the baseline. Analyzing this contour revealed that it adapts to the flow field by breaking up the near endwall vortices and thus reducing secondary flows. We found that this reduction in HTC results from the natural character of the IFM to reduce entropy production rates due to heat conduction.