Optimization of rotating blades with dynamic-behavior constraints

The optimal design of rotating pretwisted blades subject to dynamic behavior constraints is studied. The restrictions on multiple blade natural frequencies and on maximum blade dynamic deflections are considered the dynamic behavior constraints. The aerodynamic forces acting on the rotating blades are simulated as harmonic excitations. Optimization techniques of the optimality-criterion method and the method of modified feasible directions have been successfully developed and applied to minimize the weight of rotating pretwisted blades. Based on these techniques, the numerical results show that the effect of setting angle on the optimal design weight for the first frequency-constraint case is more significant than that for the second frequency-constraint case. It is also shown that the changes of pretwist angle will considerably affect the optimal design weight for the second frequency-constraint case. However the effect is not significant for the fundamental frequency-constraint case. The results also indicate that the increase of rotating speed will decrease the optimal design weight.