Fluid Mechanics Analysis Of Sounding Temperature Sensor

Due to the increasing amount of attention that has been focused on disaster prevention as well as the need of dealing with climate change, it is expected that the accuracy of the measurement air temperature with high altitude can reach to0.1℃. However, the errors caused by solar radiation may be as much as3℃or worse in upper air, which has become the bottleneck when improving the accuracy of upper air radiosonde temperature sensors. Because of some shortages in the traditional research methods, it is difficult to achieve a high precision.A computational fluid dynamics (CFD) method is employed to simulate the sounding temperature sensor, and the result can be used as a reference for actual measurement. The results show that the reflectivity of surface coating of thermistor bead and solar incident angle and sun azimuth and lead angle are important factors that affect the errors.Based on the actual sensor devices, a geometrical model of sounding temperature sensor for various lead angles is established, which utilizes a parametric design concept. Then, hexahedral grids are generated for the established geometrical model. The environment around the sensor is simulated in this model. Subsequently, convection-solar radiation coupled thermal boundary condition was applied externally. Finally, heat transfer analysis was performed by using fluid-coupling method.Errors of solar radiation were calculated using the aforementioned factors. According to the results of the calculation, three-dimensional diagrams can be accomplished. The relationship between solar radiation and the error-introducing factors can be obtained. The effect of each factor on the radiation error can vary from1.3℃to2.5℃. According to the modeling results, Marquardt and Global Optimization method can be employed in fitting formulas. Using these techniques, the solar radiation errors as a function of the several factors may be obtained precisely, quickly and easily. The simulation results can be used as a reference for error correcting, which has a potential to improve the measuring accuracy.