Research On Calibration Method And Device Of Underwater Shock Wave Pressure Sensing System

The magnitude of the underwater shock wave pressure is the main technical indicator to evaluate underwater weapon systems.Piezoelectric pressure sensor is widely used in underwater shock wave pressure test for its well-performed dynamic characteristics and high natural frequency.However,because the low-frequency characteristics of piezoelectric pressure measurement system are not ideal enough,the method of static calibration is not appropriate in the process.At present,the standard explosive pellet method is commonly used to dynamically calibrate the underwater shock wave pressure sensing system.By this method,the theoretical value is obtained according to the empirical formula of the mass of the explosive pellet and underwater shock wave pressure.The theoretical value is then used in the dynamic calibration of the measurement system.But due to the complexity of underwater explosions and the uncertainty of standard explosive pellet,the accuracy of this method is difficult to guarantee.To avoid this problem,the author presents a dynamic method to calibrate the underwater shock wave pressure sensing system based on pre-pressurized water shock tube.He has also studied the characteristics of the calibration signal and designed the mechanical structure of the calibration device.In this thesis,the method of "comparative calibration" based on pre-pressurized water shock tube is introduced to discuss the preloading system' s effect on the improvement of the calibration signal's peak value and on the elimination of sensor's "negative pressure".The author has studied the dissemination channels of value of quantity in underwater shock wave pressure measurement system and the method to obtain its dissemination characteristics.In order to study the propagation characteristics and frequency characteristics of the pressure's pulse signal inside the water shock tube,an analytic simulation model was created with the finite element software AUTODYN to find out the condition to form stable plane waves and the effective range of frequency band of the pressure's pulse signal inside the water shock tube.The similarity between the pressure's pulse signal in water shock tube and the pressure's signal of actual underwater explosion shock wave was evaluated and calculated.Based on large amount of data from the simulation,the author found out the pattern of the respective influence of the tube's cavity length,the amount of preloaded explosives and the magnitude of preloaded pressure on the peak value of the pressure's pulse signal.The author has designed a set of pre-pressurized water shock tube calibration device that meets the requirement of strengths and tightness,for which he has chosen the material of the shock tube,designed the shape of the cross section,the ways the tubes are connected and the sensors are installed and other details,and checked the strengths of the connecting pieces.According to the calibration requirements,a standard pressure monitoring system was set up and a small amount of water shock tube commissioning test was conducted.A dynamic method to calibrate the measurement system of underwater shock wave pressure based on water shock tube is studied,and a calibration device for pre-pressurized water shock tube is designed to offer technical support for this system.