Development of Intelligent Wind Turbine Generator with Tandem Rotors: Optimization of Wind Rotor Profiles

这种智能风力发电机具有以下特点。(1)两个风转子在低风速时开始旋转，但后风转子与前风转子反向旋转。(2)风速的增大使两种转速都增大，后风转子在额定风速下达到最大转速。(3)随着风速的增加，后风转子逐渐减速，并开始与前风转子同向旋转，输出可以保持不变。(4)而且，即使在风差的情况下，反向旋转也使输出更高。为了得到该机组的最佳型线，在台架试验中对双旋转电枢式双馈感应发电机的特性进行了研究，并在风洞和CFD.1中对两种风力转子的叶片型线进行了优化。发电机经试验证实，该发电机与串联式风力发电机配合良好，输入电路即内电枢可获得更多的电动机和二次输出。两风转子最优直径比随着后风转子直径的增大，输出增大，比值D=（后风转子直径）/（前风转子直径）=1。D=0.84时的后风转子在较高风速下可以与前风转子同向旋转，而D=0.84以上的后风转子不能随风速变化而改变旋转方向。即最优比值D=0.84.3左右。两风转子之间的最佳间距是使后风转子尽可能靠近前风转子，以获得丰硕的输出。风转子周围的流动情况每经过风转子子午线流速减小一次。在较高的风速下，后风转子开始与前风转子同向旋转，使气流沿轮毂壁面上游流动。然后，后风转子发挥在制动器和/或俯仰控制，抑制过旋转的地方。建议的最佳叶片轮廓，这是可取的，前风转子的叶片轮廓没有弧度在轮毂侧给予足够的风能后风转子。串级风转子的噪声水平大于单级风转子的噪声水平，反向旋转时的噪声水平大于同方向旋转时的噪声水平。噪声随后风转子直径的减小而减小。少

This intelligent wind turbine generator has the following peculiarities. (1) Both wind rotors start rotating at the low wind speed, but the rear wind rotor counter-rotates against the front wind rotor. (2) The increase of the wind speed makes both rotational speeds increase, and the rear wind rotor reaches the maximum rotational speed at the rated wind speed. (3) With more increment of the wind speed, the rear wind rotor decelerates gradually and begins to rotate in the same direction as the front wind rotor, and the output can be kept constant. (4) Moreover, the counter-rotation makes the output higher even if in the poor wind circumstance. To get the optimum profiles of this unit, the characteristics of the double rotational armature type doubly fed induction generator were examined in the bench tests, and the blade profiles of both wind rotors were optimized in the wind tunnel and by CFD.1. GeneratorIt was confirmed that the generator works well in cooperation with the tandem wind r … More otors and the secondary output can be got from the input circuit, namely the inner armature.2. Optimum diameter ratio between both wind rotorsThe output increases with the increase of the rear wind rotor diameter, under the ratio D=(rear wind rotor diameter)/(front wind rotor diameter)=1. The rear wind rotor under D=0.84 can rotate in the same direction as the front wind rotor at the higher wind speed, but the rotor over D=0.84 can not change the rotational direction in response to the wind speed. That is, the optimum ratio is about D=0.84.3. Optimum span between both wind rotorsIt is desirable to make the rear wind rotor close to the front wind rotor as possible, to get the fruitful output.4. Flow condition around wind rotorsThe meridian flow velocity decreases every through the wind rotor. At the higher wind speed, the rear wind rotor comes to rotate in the same direction as the front wind rotor, and makes the flow runs upstream along the hub wall. Then, the rear wind rotor plays in place of the brake and/or pitch control which suppresses the over rotation.5. Proposal of the optimum blade profileIt is desirable that the blade profile of the front wind rotor has not the camber at the hub side for giving the sufficient wind energy to the rear wind rotor.6. Acoustic noiseThe noise level of the tandem wind rotors is larger than that of the single wind rotor, and the level at the counter-rotating operation is larger than that at the rotating operation in the same direction. The noise becomes lower with the decrease of the diameter of the rear wind rotor. Less