桨叶分段线性扭转对降低旋翼振动载荷的作用分析OACSTPCD

Piecewise linear blade twist is studied as a method for reducing the rotor vibratory loads.A rotor model based on an elastic beam concept is used to predict the loads.A four-bladed rotor with a shape similar to the UH-60 rotor is used as a baseline for comparisons.The blade is divided into three segments,which are inner,middle and outer segments respectively.Effect of the twist at different segments on the loads is discussed.The twists at all the segments can reduce the 4/rev(revolution)vertical hub force at low speeds.The 4/rev force can be reduced by 99.5%with a-24°/R(R is the blade radius)twist at the middle segment at 80 km/h.The twist at the inner segment is not helpful for reducing the 4/rev rolling and pitching moments,while the twists at other segments can control both the moments at most speeds.A parameter sweep is conducted to minimize these loads.To reduce the 4/rev force,all the segments need to be twisted at low speeds,while untwisted blades perform better at high speeds.For controlling the 4/rev moments,the outer segment should be highly twisted at low speeds,while high twists at the middle segment are essential at medium to high speeds.