Multi-Regime Shape Optimization of Fan Vanes for Energy Conversion Efficiency using CFD, 3D Optical Scanning and Parameterization

Abstract An enhanced reverse engineering procedure was developed for roof fan re-design. An original numerical workflow for robust shape optimization based on maximum energy conversion efficiency was developed. It operates using a sample of multiple operating regimes coupled with CFD simulations. The initial shape solution was originally obtained in point cloud form by optical 3D scanning and subsequent B-spline based parameterization of shape. The CFD simulation of the scanned shape using 3D RANS based software was shown to agree very well with the measured features, experimentally obtained in our lab with the actual initial-shape fan. By manipulating the control points of parametric curves, the developed evolutionary optimization workflow was subsequently able to create shape-optimized vanes. This original procedure was applied to cases of constant-thickness and profiled single curvature vanes, both for single-regime and robust multi-point operating conditions. The corresponding increase in efficiency gained by our computational procedure was correlated with respective velocity and pressure distributions and suppression of flow separation. The novel numerical procedure developed here therefore provides a numerical framework for generic object geometry to re-shape itself autonomously. The change in shape ensures maximum energy conversion efficiency for a given composition of operating regimes. The gain in efficiency with optimized vane shapes proves to be significant in the wide range of flow rates around the best efficiency point.

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