超声风速风向仪设计

发布时间：2018-07-12 14:57

本文选题：风速风向仪 + 超声　；参考：《电子科技大学》2014年硕士论文

【摘要】：介绍了风速风向仪的几种实现方式,对采用超声来实现风速测量的几种方法的原理、各自的优缺点,以及影响测量精度因素进行了讨论,并对超声风速风向仪国内外的国内外研究现状做了介绍。分别从超声换能的谐振频率与到达时间测量准确度、超声传播衰减特性、发射信号指向性等几个参数的关系的角度进行了分析,选择了适合的工作频率。对换能器结构、换能器的压电材料、声阻抗匹配层设计、背衬材料、工艺流程等进行了讨论。分析了两种类型超声换能器的设计方法:第一种是工作在径向振动模式来实现的单频压电超声换能器;第二种是利用压电材料柱体的径向和纵向振动模态接近,通过两种模态耦合来形成的宽带换能器。多换能器组的空间拓扑结构对矢量风速的测量准确度有重要影响,本文对直通式和反射式两种结构分别进行了分析,提出了一种两者相结合的超声探头拓扑结构,并采用计算流体动力学技术对其进行了仿真分析,拓展了单个超声探头的风速测量范围。文中利用FPGA内部的锁相环设计了激励调制信号产生电路,驱动电路采用MOSFET电路实现。接收端的超声探头输出的探测信号幅度非常小,包含大量因声学干扰和电学干扰引起的噪声信号,本文设计了一种多级放大、滤波结构,放大信号的同时很好地抑制了噪声信号。放大后的模拟信号被数模转换电路转换成数字信号,并送入FPGA进行处理。文章采用硬件编程语言,实现了超声信号传播时间测量,讨论并比较了过零检测法、相位检测法和相关检测法等三种超声信号到达时间测量方法。本文完成了一种二维超声风速风向仪设计,通过采用直通式与反射式相结合的超声探头,使风速仪在0~150m/s风速范围内的测量准确度优5%。
[Abstract]:Several methods of wind speed wind instrument are introduced. The principle of several methods for measuring wind speed by ultrasonic wave, their advantages and disadvantages, and factors affecting the measurement accuracy are discussed. The current research situation at home and abroad at home and abroad of the ultrasonic wind speed wind instrument is introduced. The resonance frequency and the arrival time of the ultrasonic energy exchange are measured respectively. The relationship between the quantity accuracy, the attenuation characteristic of ultrasonic propagation and the directivity of the transmitting signal is analyzed, and the suitable working frequency is selected. The structure of the transducer, the piezoelectric material of the transducer, the design of the acoustic impedance matching layer, the backing material and the process flow are discussed. The design of the two types of ultrasonic transducer is analyzed. Method: the first one is a single frequency piezoelectric ultrasonic transducer that works in the radial vibration mode. The second kind is the broadband transducer using the radial and longitudinal vibration modes of the piezoelectric material column and the coupling of the two modes. The spatial topology of the multi transducer group has an important influence on the measurement accuracy of the vector wind speed. In this paper, the two structures of direct and reflective types are analyzed, and a combination of ultrasonic probe topology is proposed. The simulation analysis is carried out by using computational fluid dynamics technology to expand the velocity measurement range of a single ultrasonic probe. In this paper, the excitation modulation signal is designed by using the phase-locked loop in FPGA. The circuit, the drive circuit is realized by the MOSFET circuit. The amplitude of the detection signal output by the receiver is very small. It contains a large number of noise signals caused by acoustic interference and electrical interference. In this paper, a multistage amplification, filter structure, magnified signal are designed and the noise signal is suppressed well. The analog signal after amplification is counted. The mode conversion circuit is converted into a digital signal and sent to FPGA for processing. In this paper, we use the hardware programming language to realize the measurement of the transmission time of ultrasonic signals, discuss and compare three methods of measuring the time of arrival of ultrasonic signals, such as zero crossing detection, phase detection and correlation detection. This paper has completed a two-dimensional ultrasonic wind speed wind direction instrument. The accuracy of the anemometer in the range of 0~150m/s wind speed is 5%.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB552

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