Research On Calibration Method Of Low Frequency Vector Hydrophone In Slow Wave Tube

This thesis is the study of the vector hydrophone calibration in the standing wave tube whose wall is made of elastic material.Previous traditional standing wave tube is made of stainless steel whose wall thickness is more greater than the radius.Under these circumstances we can get a sound field in a hard boundary tube.From a new point of view,we want to establish a standing wave field in a flexible tube whose wall is made of acrylic,and to study whether it satisfies the requirement of calibrating the vector hydrophone.The slow wave tube can not only extend the measuring frequency up to 5Hz but also provide more convenience,save more space and cost,we can prove whether this method can be applied in engineering practice.Firstly,the natural frequencies of the radiation surface,the sound tube and the sound field inside the tube were simulated by a software which is named COMSOL Multiphysics.Then we try to use the Solidworks to draw the system required parts for rendering factory to process.Then measured a large number of sound field information including the sound pressure and the vector information and water quality point vibration acceleration.After this job,we draw the experimental data of measurement in software which is named Matrix Laboratory.The results show that in the z axis direction,the acoustic pressure is positive proportion to sin(kz),the water quality point vibration acceleration is positive proportion to cos(kz),at the meaning time the fluctuation of sound pressure on water column cross is less than 0.7 dB,acceleration and pressure along the axial direction in the designed slow wave tube is proportional to sine function.After all the measurement,we know that this slow wave tube which is made acrylic of can basically meet the requirments and this is the necessary.In the end,This is a necessary condition for calibrating a vector hydrophone in a standing wave tube.Finally,we calibrated two vector hydrophones of different sizes by using this slow wave tube device whose sensitivity is known for us.Through a large number of measured data shows that the calibration device in this thesis can not only satisfy the requirement of vector hydrophone calibration but also can extend low frequency limit.The measurement results show that the size of the vector hydrophones need to be calibrated in this calibration device should be less than 60 mm,only in this case the frequency of working band will be in 5-500 Hz.