Optimization of Rotating Cooling Channel with Pin Fins Downstream of Turning Region

Abstract

The heat transfer performance of a rotating two-pass rectangular channel with staggered pin-fin arrays is optimized through Reynolds-averaged Navier–Stokes analysis, a surrogate method, and a multi-objective evolutionary algorithm. As the Pareto-optimal front produces a set of optimal solutions, the trends in the objective functions in relation to the design variables are predicted by a hybrid multi-objective evolutionary algorithm. Two objective functions related to heat transfer and friction loss, respectively, have been considered to estimate the performance of the cooling channel in turbine blades. Twodesign variables are selected, viz., the ratio of the diameter to height of the pin fins and the ratio of the streamwise spacing between the pin fins to height of the pin fins, and 20 designs are generated by Latin hypercube sampling. A response surface approximation model as a surrogate model is constructed for each objective function, and a hybrid multi-objective evolutionary algorithm is applied to obtain the Pareto-optimal front. The Reynolds number that is based on the hydraulic diameter of the channel is fixed at 10,000, while the rotation number is held constant at 0.15. The turning region upstream of the pin fins enhances the heat transfer through the channel, since a strong vortical flow structure is created in this region. At some optimal points on the Pareto-optimal front, it is found that the present multi-objective optimization enhances both the heat transfer performance and the pressure-loss characteristics. The effects of the rotation number on the heat transfer and pressure loss are also discussed.