Research On Method Of Ultrasonic Cavitation Detection Based On The Single Photon Detection Technology

The ultrasonic cavitation is a kind of dynamic processes, which commonly referred to the growth and collapse of micro-bubbles (cavitation nucleus) in the fluid when the ultrasonic pressure reaches a certain value. During this process, a local temperature near this activity has been shown to be as high as5000K, and the pressure produced may be as high as100MPa, accompanied by a strong shock wave and micro jet which may be as high as400km/h. Currently, on account of the environment with high temperature and pressure, the ultrasonic cavitation has been widely applied in life service business, chemical engineering, material science*environmental science and medicine and so on.However, the advantages and disadvantages are appeared in different applications alternately, since the ultrasonic cavitation is caused by many complex factors and the application of history is not long enough. Thus, the quantitative detection of ultrasonic cavitation is very important, because of safety and efficacy in the application. At present, a series of physical and chemical method has been adopted in the quantitative detection of ultrasonic cavitation, such as the method of time-difference, the method of cavitation noise measurement, the method of hydrophone measuring, the method of metal foil membrane detection, the method of medical image detection, the method of iodine release, the method of conductivity measuring, the method of terephthalic acid fluorescence measuring, the method of electron spin resonance (ESR) detection and the method of staining and so on. These methods are time-consuming, or fail to realize regional measurement, or difficult to achieve non-contact measurement. Therefore, a new quantitative detection method should be proposed, which has the advantage of fast measurement, non-contact detection and regional detection.In this paper, the detection method of ultrasonic cavitation based on the single photon detection technology has been proposed, and the following aspects have been done in my work.Firstly, the detection model of ultrasonic cavitation has been established. According to the mechanism of ultrasonic cavitation, it can be detected by the detection of ultrasonic cavitation bubbles. The quantitative detection method of ultrasonic cavitation bubbles has been put forward by the use of the light scattering theory, especially the Mie scattering theory. Owing to the single photon detection technology, the weak scattering light, which caused by ultrasonic cavitation bubbles, can be quantitative detected. Combined with the mechanism of ultrasonic cavitation, the light scattering theory and the theory of single photon detection, the detection model of ultrasonic cavitation has been established. Moreover, the performance of the detection method, including accuracy, stability and linearity, has been discussed. As the theoretical foundation, it will be beneficial to the development of ultrasonic cavitation detection device and the detection experiment of ultrasonic cavitation.Secondly, the detection device of ultrasonic cavitation has been developed. According to the single photon detection technology based detection model, the steady-state photon counting (SSPC) based detection device and the time-correlated single photon counting (TCSPC) based detection device have been developed, including the light source module, the structure of the optical path, the time measurement module and the data processing and control module. Moreover, by modifying the TCSPC based detection device, a laser ranging experiment has been done to verify its reliability. As the equipment foundation, it will be beneficial to the detection experiment of ultrasonic cavitation.Thirdly, the detection experiment of ultrasonic cavitation has been carried out on the basis of the the detection model and the detection device. To test the performance of these two devices, the formazin solution, which is a kind of stable particles suspension, has been adopted in the simulation experiment. By comparing their measurement results with analyzing their advantages and disadvantages, the SSPC based detection device has been confirmed as the detection device of ultrasonic cavitation. After that, some preliminary experiments have been done in different viscosity of liquid under different intensity of ultrasonic. Moreover, the ultrasonic cavitation of different zones in the sample cell has also been detected. At last, the shortcomings of the existing experiments have been analyzed and the new goals for the future work have been put forward.