Reducing solid particle erosion of an axial fan with sweep and lean using multidisciplinary design optimization

Abstract

A multidisciplinary design optimization (MDO) system is established to reduce solid particle erosion of an axial induced draft fan with sweep and lean. The method improves the erosion resistance of the fan blade in the aerodynamic design stage through a change of blade sweep and lean. The multidisciplinary design optimization approach takes the place of the traditional time-consuming design method by automatic calculation of the flow field, stress distribution, dynamic frequencies, and erosion distribution for blade, controlled by an optimization strategy. A multi-objective particle swarm optimization (MOPSO) algorithm combined with radial basis function approximation model is employed for finding a compromise between the conflicting demands of high efficiency and low average erosion rate with constraints on the pressure ratio and structural responses for the blade. The Navier–Stokes solver, finite element method (FEM) is used to predict the aerodynamic performance and mechanical performance of the blade, respectively. Particle paths in a viscous flow are calculated using the Lagrangian method and Tabakoff rebound model. And then Tabakoff erosion model is used to predict erosion of the blade surface. Several representative designs are selected along the Pareto front to verify using computer aided engineering tools. A compromise solution is used to analyze in detail. Compared with the reference design, the optimal design increases the η/ η0 slightly by 0.53%, while decreases the ɛavg / ɛavg0 markedly by 13.7%. The result shows that the optimized blade favors a reduced total pressure due to its forward sweep. The decrease of the ɛavg/ ɛavg0 is attributed to a reduced impact velocity and impact angle. The analysis of variance technique indicates that the blade lean has a direct impact on performances with respect to efficiency, erosion, and von Mises stress of the blade, and the blade sweep law near hub has an immeasurable influence on blade von Mises stress. As a conclusion, it can be drawn that the proposed approach may open a new opportunity for the design of axial fan to reduce erosion damage of blade taking other disciplines into consideration. Meanwhile, the multidisciplinary design optimization system can be extended to other turbomachinery and erosion-resistant design fields.