Research On Measurement Of Ultrasonic Transit Time Based On Sing-around Method

Pressure is one of the most important parameters in modern industry. In order to ensure the devices working properly and safely, it is necessary to monitor and control the pressure. Conventional methods, most of them belonging to the invasive method, to measure the pressure require drilling a hole in the wall of the devices, which not only induces local stress concentration, but also brings many safety problems. In this paper, a description of a method to measure the pressure non-invasively based on the ultrasonic is given. With this method, the pressure can be gotten by measuring the transit time difference of ultrasonic under different pressures.The measurement and inspection based on ultrasonic usually request accurate measurement of ultrasonic transit time in the medium. A sing-around device was developed to measure ultrasonic transit time for the ultrasonic nondestructive measurement of pressure. In the device, the electrical signal from the receiver is gated out to retrigger the transmitter. The device employs stable circuitry to maximize stability and detection sensitivity. The results of experiment suggest that detection of a 0.2ns change in transit time difference should be detectable with this device. The main work is listed as follows:(1) A method of sing-around which is able to measure the transit time in high precision is presented. Based on this method a device was designed.(2) The device was developed to measure the pressure based on the Rayleigh Wave. A serial of system testing on this device show that it has high precision and stability.(3) A number of experiments were done with this device. The practical experiments clearly show that the model of the ultrasonic nondestructive measurement of pressure is correct. It suggests that the monitoring of the surface wave velocity variations might be used for characterizing the pressure in the vessel.(4) The affect of temperature was discussed according to some phenomena in the experiment. A method was presented to correct the errors caused by the temperature fluctuation. The experimental results show that this method can eliminate or weaken the affect of temperature effectively.