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The work presented in this paper used rigorous 3D flow-field analysis combined with multi-objective constrained shape design optimization for the design of complete blade + bladelet configurations for a three-blade horizontal-axis wind turbine. The fluid flow analysis in this work was performed using Openfoam software. The 3D, steady, incompressible, turbulent flow Reynolds-Averaged Navier–Stokes equations were solved in the rotating frame of reference for each combination of wind turbine blade and bladelet geometry. The free stream uniform wind speed in all cases was assumed to be 9 m s−1. The three simultaneous design optimization objectives were as follows: (a) maximize the coefficient of power, (b) minimize the coefficient of thrust force, and (c) minimize twisting moment around the blade axis. The bladelet geometry was fully defined by using a small number of parameters. The optimization was carried out by creating a multidimensional response surface for each of the simultaneous objectives. The response surfaces were based on radial basis functions, where the support points were designs analyzed using the high-fidelity computational fluid dynamics (CFD) analysis of the full blade + bladelet geometry. The response surfaces were then coupled to an optimization algorithm in modefrontier software. The predicted values of the objective functions for the optimum designs were then again validated using Openfoam high-fidelity analysis code. Results for a Pareto-optimized bladelet on a given blade indicate that more than 4% increase in the coefficient of power at minimal thrust force penalty is possible at off-design conditions compared to the same wind turbine rotor blade without a bladelet.

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The ability of various arrays of micro pin-fins to reduce maximum temperature of an integrated circuit with a 4 × 3 mm footprint and a 0.5 × 0.5 mm hot spot was investigated numerically. Micro pin-fins having circular, symmetric airfoil and symmetric convex lens cross sections were optimized to handle a background uniform heat flux of 500 W cm−2 and a hot spot uniform heat flux of 2000 W cm−2. A fully three-dimensional conjugate heat transfer analysis was performed and a multi-objective, constrained optimization was carried out to find a design for each pin-fin shape capable of cooling such high heat fluxes. The two simultaneous objectives were to minimize maximum temperature and minimize pumping power, while keeping the maximum temperature below 85 °C. The design variables were the inlet average velocity and shape, size and height of the pin-fins. A response surface was generated for each of the objectives and coupled with a genetic algorithm to arrive at a Pareto frontier of the best trade-off solutions. Stress–deformation analysis incorporating hydrodynamic and thermal loads was performed on the three Pareto optimized configurations. Von-Mises stress for each configuration was found to be significantly below the yield strength of silicon.

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