作　　者： ; ; ; (张俊杰）;

机构地区： 南京大学物理学院近代声学教育部重点实验室

出　　处： 《南京大学学报（自然科学版）》 2003年第4期517-524,共8页

摘　　要： 超声波测温是近40年发展起来的一种新型的测温技术,其理论基础是超声波传播速度与介质温度有确定关系,目前的超声测温计存在着自动化程度低、在线检测困难以及测量精度差等缺点,给出了一种以热处理温度为3 000℃的优质石墨棒作为测温介质、采用基于超声波脉冲技术的零点回鸣法测量声速、并通过微机控制自动跟踪测量温度的超声波测温系统。实验结果和理论分析表明该测温系统工作稳定,具备长期自动跟踪测温能力,系统声时测量分辨率可达0.2μs。 On the basis that ultrasound velocities are determined by the temperature of the objects, several ultrasonic thermometries have been presented in the past forty years. But most of the methods are with lower automatization, lower accuracy and difficult in on-line control. By using a pulse echo technique and zero point-around method, the automatic measurement of the travel time of ultrasound can be performed by our system, which consists of an ultrasound generator, a transducer, a graphite bar and a computer. When the distance of the ultrasonic propagation is determined, the measurement of the ultrasound velocity is equivalent to that of the ultrasound travel time. Thus the automatic temperature measurement is accomplished. A series of experiments, in which one end of the graphite bar is put into a furnace, for the measurement of ultrasound travel time in furnace's temperature ranging from 190 to 605℃ are elaborated in this paper. The results show that the ultrasound travel time reaches the maximum of 1 574. 4μs at the temperature of 430 t. The system keeps track of the ultrasound travel time accurately and runs stably even after continuously working for more than 48 hours. Its capacity of tracking allows for a time variation within 25μs with the time resolution of 0.2μs. Besides, the theoretical calculation of the temperature distribution in the graphite bar using FEM is obtained. Then the ultrasound travel time and velocity are also calculated by the longitudinal wave formula of solids and the Young's modulus variation with the temperature. The theoretical values are in good agreement with the experimental results. While the temperature of the graphite bar ranges from 300 to 1 000 ℃ , the theoretical variation of the ultrasound travel time is 81 μs. Therefore a better sensitivity and precision can be obtained by our system with a 0.2μs time resolution. In addition, the system is capable of on-line controlling in a wide range of temperature.

关 键 词： 超声波测温 在线检测 测量精度 超声波传播速度 介质温度 超声波脉冲

领　　域： [理学] [理学] [一般工业技术] [机械工程] [机械工程]