The Design Of Acoustic Parametric Array Wind Speed Measurement System

Accurate measurement of wind speed is of great significance on many occasions.In order to obtain an accurate wind speed,the method for measurement of wind speed has been developing all the time,including the mechanical method,the hotwire measurement method and the acoustic method.Nowadays the ultrasonic wind speed measurement method is popularly used.However,the high frequency and short transmission distance of ultrasonic give rise to a rather short measurement range.The acoustic parametric array system can produce high-pointing low-frequency sound.Its sound waves travel a great distance with a clear distribution of sound fields.All of these features make it possible to measure wind speed in large spaces.Based on it,this thesis puts forward a new method for simulating the wind field and the sound field.An acoustic parametric array wind speed measurement system is designed based on the triangle measuring model developed by adopting the phase difference method and parametric array technology for acoustic.Firstly,the theory of acoustic parametric array is studied,and the sound field of acoustic parameters is simulated by analyzing the nonlinear characteristics of acoustic parameters.The sound field distribution of different signal frequency is emphatically analyzed and compared with the ultrasonic sound field.The feasibility of measuring the wind speed by the acoustic parametric array is verified through theoretical research and a simulation model.Secondly,the wind field is simulated by using the vector autoregressive(AR)model and the wavelet decomposition method.On the basis of the wind field,the sound field of ultrasonic and acoustic array are simulated.The simulation results show that the sound field is shifted along the direction of the wind field,which verifies the feasibility of using the acoustic parameter array to measure the wind speed.Then the wind speed measurement model based on phase difference is established,and the calculation formula of wind speed and wind direction is deduced according to the established wind speed measurement model.Afterwards,the preprocessing algorithm of the acoustic parametric array is analyzed by simulation comparison experiments.It is pointed out that the required bandwidth of the full carrier SSB modulation algorithm is half the width of the DSB modulation algorithm.Moreover,the full carrier SSB modulation algorithm is power saving and has no distortion in the single frequency input mode.Therefore,the full carrier SSB modulation algorithm is chosen as a signal processing algorithm in this paper.Finally,the hardware and software experimental platform for the acoustic parameters wind speed measurement system is designed.The theoretical research and simulation is verified by the signal transmission and reception test.The system of acoustic parameters based on phase difference is developed,tested and analyzed respectively.The test results show that the acoustic parameters wind speed measurement system can provide both accurate measurement of wind speed and measurement of wind speed in large spaces.