Research On Particles Flow Characteristics And Its Disturbance On Temperature Measurement For Composite Blackbody Cavity Sensor

Currently, blackbody cavity liquid steel continuous temperature measurement sensor is widely used in tundish temperature measurement.Because of the structure of double casing, the response speed and stability of temperature measurement are influenced by its structure. For the closed bottom inner tube, creep and thermal shock behaviour will happen when temperature is high. So it leads to the fracture of inner tube. In the improvement scheme, the closed bottom of inner tube is removed and length of inner tube is shortened, Nevertheless, another problem appeared that soot would generate from the outer tube at high temperature which affects the accuracy of temperature measurement seriously. Therefore, nitrogen was blown into the cavity to exhaust soot. In tackling these questions, this paper do a study on the particle flow characteristics and a analysis of effects of exhausting soot on sensor structure and operating parameters. Then, generating the model between particle concentration and temperature measurement. The paper do a research on ieterference of measured temperature. The main researches are as follows:(1) Establishment of a model of composite cavity’s coupled fields. In this thesis, it analyse the mechanism of heat and mass transfer and particle flow characteristics. And make modification and improvement on the coupled field model.(2) Optimization of sesor structure and operating parameters. This paper do a research on the change of particle concentration field, when the factors changed, for example, flow rate of nitrogen,the distance between inner tube and the bottom of target surface and outlet etc. Then give result of the optimum operation condition. The result showed that important factors of all are nitrogen flow rate and the distance between inner tube and target surf ace. When the distance between inner tube and target surface is 390mm and nitrogen flow rate is 1.5m3/h, the effect of smoke exhaust is better than others.(3) Model of measured temperature interfence. Particle concentration obtain through simulation,then compute the theoretical temperature with model established, and compare with experimental data to verify the accuracy of the model. The results show that:under different simulation condition of use of sensor, the relative deviation is less than 20%.The results received from simulation can be used to guide the actual manufacture and application of the sensor.