Algorithm Research And Transducer Array Design In Three-dimensional Ultrasonic Wind Measurement System

Ultrasound wind measurement has been attracted much attention as the mainstream method of meteorological wind measurement,and systematic research on ultrasonic wind measurement has gradually deepened in recent years.However,Traditional ultrasonic wind measurement system research often ignores the characteristics of fluid flow in wind field and the characteristics of ultrasonic signal noise distribution accompanying fluid transmission.In the algorithm research,the Gaussian model with low matching degree is directly applied,and in the array research,the influence of shadow effect is ignored,which result in lower system accuracy and stability.Based on the characteristics of Ultrasonic Wind measurement,this paper expounds its advantages and analyses the technical difficulties of current research,and determines the research directions for improving the accuracy and stability of the system measurement: the research on the algorithm of ultrasonic time delay estimation,the design of three-dimensional ultrasonic transducer array,the selection and design of hardware and software of the system.The research results of each part are applied to the three-dimensional ultrasonic wind measurement system.The theoretical accuracy and stability of the system are validated by simulation test of each part,and the performance indicators of the system in practical application are verified by system overall analysis and test.The phenomenon of non-Gaussian noise in the transmission of ultrasonic signals is very serious,which brings difficulties to the processing of time delay estimation algorithms.Aiming at this problem,this paper proposes a generalized fractional low-order covariance time delay estimation algorithm based on S?S-FLOCS.Based on the traditional time delay estimation algorithm,this method considers the distribution characteristics of colored noise,improves the filtering method with symmetric alpha stable distribution model,introduces fractional loworder covariance in spectrum estimation process,and builds filter with covariance coefficient parameters.The peak detection is performed on the signal processed by the covariance correlation function.In simulation,the root mean square error and standard deviation are analyzed by configuring different noise environments and different SNR conditions.Aiming at the problem of ignoring the influence of shadow effect in transducer arrays commonly used in three-dimensional ultrasonic wind measurement technology,this paper designs a non-positive array that imitates the special tetrahedral edge based on the viscous compressible unsteady Newtonian flow field.The array increases the uniformity of wind velocity between the transducer probes by reducing the turbulence in the wake region of the wind measurement path.The k-? turbulence model is selected in the array simulation,the transducer array model is established by GAMBIT software,and the environmental parameters such as gas flow rate and Reynolds number are configured in the FLUENT software to simulate the data results of the array in the low-velocity laminar flow region and the high-velocity turbulent region.Analyze its velocity distribution cloud map and wind path velocity line chart.Combining time delay estimation algorithm and transducer array,the three-dimensional ultrasonic wind measurement system experimental platform based on FPGA chip and Verilog HDL language is built.The overall framework and main functions of the system are determined,and the design of hardware platform and software platform is completed.Hardware design mainly includes core processing and control circuit,power supply circuit,ultrasonic driving and receiving circuit,signal acquisition circuit,storage circuit and display circuit.Software design mainly includes the overall software design process of FPGA,ultrasonic logic control,algorithm processing.The field test,wind tunnel test and basic environmental test of the designed three-dimensional ultrasonic wind measurement system are carried out.Based on the analysis of the current research hotspots of three-dimensional ultrasonic wind measurement,combined with the theoretical knowledge of digital signal processing and hydrodynamics,this paper proposes a generalized fractional low-order covariance time delay estimation algorithm based on S?S-FLOCS,designs a non-orthogonal transducer array,and establishes an experimental platform for three-dimensional ultrasonic wind measurement system.The experimental results show that the designed system basically achieves the expected target and has high accuracy and stability.