横风作用下移动点湍流脉动特性风洞试验研究

Experimental research on turbulent fluctuation characteristics experienced at a moving point under crosswind

为了研究移动点历经的湍流脉动风特性,设计了一套能够实现测量探针以均匀速度在流场中移动的试验系统,测量了不同风速-车速比(风速与移动点速度的比值)下的湍流脉动特性,提出了半椭圆湍流积分尺度模型,分析了与静止点观测结果相比的湍流脉动风速谱及能谱的变化。研究结果表明,移动点测得的湍流脉动特性与静止点测量结果存在明显的不同。对于某一固定来流风速,随着移动点速度的增加,纵向湍流积分尺度减小,相比Balzer及Cooper积分尺度模型,半椭圆模型的描述更加准确。基于半椭圆模型的脉动速度谱具有较高的精度,移动点历经的湍流谱能量因运动而重新分布,并表现出明显的Doppler效应。随着观测点移动速度的增加,脉动速度谱整体向更高的频率偏移,高频区域中的谱值增大,低频区域中的谱值减小,且能量向更高的波数区传递。

In order to study the turbulent fluctuation characteristics experienced at a moving point,a test system that can realize the measurement probe moving in the flow field at a uniform speed was designed,and the turbulent fluctuation characteristics at different speed ratio of the wind to the moving point was measured.A semi-elliptical turbulence integral scale model was proposed,the changes of the turbulent fluctuating wind speed spectrum and energy spectrum compared with the results at a stationary point were analyzed.Results show that the turbulent fluctuation characteristics measured at a moving point are significantly different from those measured at a stationary point.For a certain incoming wind speed,as the speed of the moving point increases,the longitudinal turbulence integral scale decreases,and the description of the semi-elliptic model is more accurate compared with the Balzer’s and Cooper’s integral scale models.The fluctuating speed spectrum based on the semi-elliptic model has high accuracy.The turbulent energy spectrum experienced at a moving point is redistributed due to the movement,and it shows an obvious Doppler effect.As the moving speed of the observation point increases,the overall fluctuating speed spectrum shifts to higher frequencies,the spectral value increases in the high frequency region and decreases in the low frequency region,and the energy is transferred to the higher wavenumber region.