CFD Analysis And Heating Strategy Design Of Heated Twin Humidity Sensor

Heated twin humidity sensor can achieve continuous detection of atmospheric humidity. In order to improve the response speed, it should be exposed outside of the radiosonde, directly contacts with air. At this time, hydrometeors like liquid, ice crystals will cover on the surface of heated twin humidity sensor, which makes it easy to lower measuring precision and response speed. In order to improve the measuring precision and response speed, it is necessary to dry the heated twin humidity sensor.In this paper, software like Pro/E is used to build3-D model of four kinds of the size of the heated twin humidity sensor; The modular method of ICEM CFD is used to mesh heated twin humidity sensor by which a higher quality of grid is obtained, the calculation time is reduced and the calculation accuracy is improved; Computational fluid dynamics (CFD) method is used, steady-state analysis has been implemented to simulate the interaction of the twin sensors with different spacing. Transient analysis has been carried out to obtain dynamic parameters, including the lengths of time heating and cooling stages.The results show, for cases where rising velocity of the radiosonde is6m/s, for sensor which size is6mm*4mm*0.625mm, if the distance between two sensors is no less than3mm, their temperatures do not affect each other; for sensor which size is3mm*2mm*0.5mm, if the distance between two sensors is no less than1.5mm, their temperatures do not affect each other; for sensor which size is1.5mm*1mm*0.4mm, the temperatures of two sensors do not affect each other under the condition that their distance is no less than1mm; for sensor which size is0.75mm*0.5mm*0.4mm, the temperatures of two sensors do not affect each other, if their distance is no less than0.8mm. According to the simulation results, for heated twin humidity sensor which size is6mm*4mm*0.625mm, two heating strategies, high-altitude and low-altitude modes, are proposed to optimize the measurement cycle, where40P℃and46℃are selected as the amplitudes of temperature drop, respectively; for heated twin humidity sensor which size is3mm*2mm*0.5mm, high-altitude and low-altitude modes, are proposed to optimize the measurement cycle, where42℃and48℃are selected as the amplitudes of temperature drop, respectively; for heated twin humidity sensor which size is1.5mm*1mm*0.4mm or0.75mm*0.5mm*0.4mm, high-altitude and low-altitude modes, are all proposed to optimize the measurement cycle of48℃.