| 串列扑翼间前缘涡在不同间距下对平均推力的影响 |
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| 作者姓名： | 贾博博 宫武旗 |
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| 作者单位： | 西安交通大学能源与动力工程学院流体机械及工程系，陕西西安 710049 |
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| 摘 要： | 利用压力传感器测量扑翼的瞬时力，利用数字粒子测速仪（digital particle image velocimetry，DPIV）系统测量扑翼的前缘涡以及周围的流场，来揭示前缘涡在不同间距下对扑翼平均推力的影响.实验在一个低Reynolds数循环水洞中进行，两串列扑翼均做二维正弦平动.在固定的相位差下，当间距增加时，后翅前缘涡对前翅的影响具有相似性，均提高或者均降低前翅的平均推力.前翅平均推力的提高是由于后翅的前缘涡提高了前翅尾部的射流速度以及有效攻角.随着间距的增加，后翅前缘涡对前翅的影响急剧下降，使得前翅的平均推力快速接近于单翼值.在固定的相位差下，当间距增加时，前翅的脱落涡对后翅的影响变化非常大，后翅的平均推力可能先升高后降低，这是因为间距改变了前翅脱落涡作用于后翅的时间点.当前翅脱落涡遇到后翅，并且和后翅的前缘涡有相同的旋转方向时，前翅的脱落涡会抑制后翅前缘涡的形成，并且后翅的有效攻角减小，其平均推力降低.如果这两个涡的旋转方向相反，那么后翅有效攻角就会增大，平均推力值就会提高.
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| 关 键 词： | 串列扑翼 水洞 平均推力 前缘涡 DPIV系统 |
| 收稿时间： | 2017-01-15 |
Influence of Leading-Edge Vortex on Mean Thrust of Two Plunging Wings in Tandem under Different Spacing Distances |
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| Affiliation: | Department of Fluid Machinery and Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China |
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| Abstract: | An experimental study was performed in a low Reynolds number water tunnel for two tandem wings undergoing a 2D sinusoidal plunging motion. To investigate the effect of the spacing distance between the forewing and hindwing on the mean thrust coefficients of the two wings, a three-component force sensor and a two-dimensional digital particle image velocimetry (DPIV) system were used to measure the aerodynamic forces of the wings and to observe the leading edge vortex (LEV) around them. When the phase difference between the forewing and hindwing was fixed, the effect of LEV around the hindwing on the forewing shows similarity at different spacing distances, namely, increasing or decreasing the mean thrust of the forewing all the time. The increase of the mean thrust coefficient of the forewing is due to the LEV of the hindwing enhancing the jet velocity behind the forewing and its effective angle of attack. As spacing distance increases, the effect of the LEV of the hindwing on the forewing declines sharply, resulting in the mean thrust coefficient of the forewing approaching to the value of the reference single wing quickly. When the phase difference was fixed, the effect of the forewing-shed vortex on the hindwing was large. The mean thrust of the hindwing may firstly increase and then decrease as the spacing distance increases. This may due to the spacing distance changes the timing of the forewing-shed vortex affecting the hindwing. When the forewing-shed vortex encounters the hindwing and has an opposite sense of rotation with the LEV around the hindwing, the effective angle of attack of the hindwing and the mean thrust of the hindwing increase. If the two vortices have the same sense of rotation, the value of the hindwing decreases. |
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