Research On Shock Tube Velocity Measurement Technique And Design Of Processing Circuit

Shock tube has been commonly used to demarcate pressure sensor dynamically.The accurate measurement of shock wave velocity is an important parameter to calibrated for pressure sensor.There are plurality of faults in the velocity measuring apparatus for shock wave propagation,such as complex mounting structure,large measurement error,etc.And then velocity measuring method of shock tube therefore is researched in this study in combination with the velocity measuring technology in light screen detection,and a new method of optical-probe velocity measurement has been proposed.The thesis focuses on the following aspects:(1)Optical-probe of velocity measuring is designed for shock wave velocity measurement.The optical-probe sensor is designed according to the theory of shock wave propagation and the principle of velocity measuring technology of light screen detection.The selection of light source and detector have been done,and then the light source and the installation structure of detectors both based on the optical fiber transmission are also designed acording to the external structure of shock tube.(2)Signal processing circuit with high sensitivity and high frequency response is designed.The corresponding signal detection circuit and amplification circuit are designed by means of the selected detector,so as to realize the photoelectric conversion of output signal when the shock wave went through the detection area,the amplification and driven of signal and so on.Thereby,the signal which can be discerned by signal acquisition instrument is output.(3)The signal extraction method of shock wave of the moment through screen time is researched.It has been studied the extraction of the feature moment of shock wave signal by means of singularity detection on wavelet transform in the algorithm of weak signal,so as to obtain the time through which the shock wave crossed from two-way optical probe detection field.And thereby the propagation velocity of the shock wave is calculated.(4)The relevant validation test is done by establishing the velocity measuring device of optical probe.It comprises the steps as follows:According to the overall design of the optical probe velocity measurement,the process of physical changes when optical probe went through screen is simulated by controlling the changes of light energy of light source in laboratory,to verify the response characteristics of processing circuit.At last,the time value between two-way signals is calculated by means of taking feature points of two-way signals with wavelet singularity detection method.With the optical probe simulation tests result,the feasibility of design scheme is verified.