减弱湍流影响的超声波测风技术研究

发布时间：2018-04-26 23:22

本文选题：阵列 + 圆柱绕流　；参考：《南京信息工程大学》2017年硕士论文

【摘要】：当前超声波测风阵列均存在圆柱或类圆柱结构,在流场中每个圆柱结构均等同于一个涡街发生器。当风速和圆柱间间距不同时,决定涡形态的雷诺数值大小相异,即流体绕柱流动产生的湍流形态发生变化,测风路径上流场分布不稳定,造成风速和风向信息采集源误差。减弱超声波测风阵列中湍流对测风路径的干扰,降低湍流对信号采集精度的影响,提高超声波测风精度,在气象探测领域具有重要的理论意义和应用价值。本文分析了换能器阵列影响风流场的因素,改进了超声波测风阵列设计,推导了风速和风向计算公式。通过仿真,与两种常用的超声波测风阵列进行了比较,通过对改进型阵列和对比阵列建模分析,降低了湍流对测风精度的影响,验证了所设计阵列的稳定性和有效性;结合软硬件设计,建立了测风实验平台。具体工作内容如下:采用六个收发一体的超声波换能器,设置独立的三条测风路径,根据不同来流方向,建立了风速计算模型,推导了风速和风向计算公式,结合换能器晶片的工作特性,对换能器选型进行了理论计算,降低了换能器阵列的阴影效应。利用FLUENT等软件,对改进型等边三角阵列,十字相交阵列,塔式结构进行建模,通过网格划分,高度离散阵列测风区域,设置不同雷诺数、来流风速和风向等参数,仿真了流场在三种不同阵列中分布特性,得到阵列速度云图和测风路径速度变化图,通过分析不同雷诺数下测风路径上涡的形态对风速影响,验证了测风阵列改进后的的稳定性和有效性,说明了所设计阵列能提高测风精度。同时通过仿真分析,指出了阵列密集,圆柱数量多,在空气绕流时改变了换能器周围流场分布,增强了换能器间耦合作用,使湍流加剧,影响测量精度,这为测风阵列小型化设计提供了理论依据。结合所设计的超声波测风阵列,分析了测量工作原理,设计了测量电路,基于时差法,搭建了实验平台。通过在实际风场中测试,分析了不同路径超声波渡越时间之间的差异,验证了湍流扰动对测风精度影响,为进一步完善超声波测风系统打下了坚实的基础。
[Abstract]:At present, there are cylindrical or cylindrical structures in the ultrasonic wind array. In the flow field, each cylindrical structure is equal to a vortex generator. When the wind speed and the distance between the cylinders are different, the Reynolds number which determines the vortex shape is different, that is, the turbulent flow pattern caused by the flow around the cylinder changes, and the distribution of the flow field on the wind measurement path is unstable, which results in the source error of collecting wind speed and wind direction information. It is of great theoretical significance and application value to reduce the interference of turbulence in ultrasonic wind array to wind path, to reduce the influence of turbulence on signal acquisition accuracy, and to improve the accuracy of ultrasonic wind measurement. In this paper, the influence factors of transducer array on wind flow field are analyzed, the design of ultrasonic wind array is improved, and the calculation formulas of wind speed and wind direction are derived. The simulation results are compared with two kinds of ultrasonic wind measurement arrays. By modeling and analyzing the improved array and contrast array, the influence of turbulence on the wind measurement accuracy is reduced, and the stability and effectiveness of the designed array are verified. Combined with the design of software and hardware, the experimental platform of wind measurement is established. The main contents of the work are as follows: using six ultrasonic transducers as a whole, three independent wind measuring paths are set up. According to the different flow directions, the wind speed calculation model is established, and the calculation formulas of wind speed and wind direction are derived. Combined with the working characteristics of the transducer chip, the selection of the transducer is calculated theoretically, which reduces the shadow effect of the transducer array. Using FLUENT and other software, the improved equilateral triangular array, cross intersection array and tower structure are modeled. The parameters such as different Reynolds number, wind speed and wind direction are set up by grid division, height discrete array wind measurement area, etc. The distribution characteristics of the flow field in three different arrays are simulated, and the array velocity cloud map and the wind path velocity change diagram are obtained. The effect of vortex shape on the wind speed is analyzed under different Reynolds numbers. The stability and effectiveness of the improved wind measurement array are verified, which shows that the designed array can improve the accuracy of wind measurement. At the same time, through simulation analysis, it is pointed out that the array is dense, the number of cylinders is large, the distribution of flow field around the transducer is changed when the air flows around, the coupling effect between the transducers is enhanced, the turbulence intensifies, and the measurement accuracy is affected. This provides a theoretical basis for the miniaturization design of wind measurement array. Combined with the designed ultrasonic wind measurement array, the principle of the measurement is analyzed, the measuring circuit is designed, and the experimental platform is built based on the time difference method. The difference of ultrasonic transit time between different paths is analyzed by testing in actual wind field. The influence of turbulence disturbance on wind measurement accuracy is verified, which lays a solid foundation for further improvement of ultrasonic wind measurement system.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB55

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