He Xiao-Ting, Ran Jun-Song, Wu Ji, Li Fei-Yan, Sun Jun-Yi
School of Civil Engineering, Chongqing University, Chongqing 400045, China.
Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University), Ministry of Education, Chongqing 400045, China.
Sensors (Basel). 2024 Sep 28;24(19):6291. doi: 10.3390/s24196291.
A circular capacitive rainfall sensor can operate from non-touch mode to touch mode; that is, under the action of enough rainwater, its movable electrode plate can form a circular contact area with its fixed electrode plate. Therefore, the weight of rainwater is borne by only its movable electrode plate in non-touch mode operation but by both its movable and fixed electrode plates in touch mode operation, and the total capacitance of its touch mode operation is much larger than that of its non-touch mode operation. Essential to its numerical design and calibration is the ability to predict the deflection shape of its moveable electrode plate to determine its total capacitance. This requires the analytical solution to the fluid-structure interaction problem of its movable electrode plate under rainwater. In our previous work, only the analytical solution for the fluid-structure interaction problem before its movable electrode plate touches its fixed electrode plate was obtained, and how to numerically design and calibrate a circular non-touch mode capacitive rainfall sensor was illustrated. In this paper, the analytical solution for the fluid-structure interaction problem after its movable electrode plate touches its fixed electrode plate is obtained, and how to numerically design and calibrate a circular touch mode capacitive rainfall sensor is illustrated for the first time. The numerical results show that the total capacitance and rainwater volume when the circular capacitive rainfall sensor operates in touch mode is indeed much larger than that when the same circular capacitive rainfall sensor operates in non-touch mode, and that the average increase in the maximum membrane stress per unit rainwater volume when the circular capacitive rainfall sensor operates in touch mode can be about 20 times smaller than that when the same circular capacitive rainfall sensor operates in non-touch mode. This is where the circular touch mode capacitive rainfall sensor excels.
圆形电容式降雨传感器可从非接触模式切换到接触模式；也就是说，在足够雨水的作用下，其可移动电极板能与固定电极板形成圆形接触区域。因此，在非接触模式运行时，雨水重量仅由其可移动电极板承担，而在接触模式运行时则由可移动和固定电极板共同承担，且其接触模式运行时的总电容量远大于非接触模式运行时的总电容量。对其进行数值设计和校准的关键在于能够预测其可移动电极板的挠曲形状以确定其总电容量。这就需要求解其可移动电极板在雨水作用下的流固耦合问题的解析解。在我们之前的工作中，仅得到了可移动电极板接触固定电极板之前的流固耦合问题的解析解，并说明了如何对圆形非接触模式电容式降雨传感器进行数值设计和校准。本文首次得到了可移动电极板接触固定电极板之后的流固耦合问题的解析解，并说明了如何对圆形接触模式电容式降雨传感器进行数值设计和校准。数值结果表明，圆形电容式降雨传感器在接触模式下运行时的总电容量和雨水量确实远大于其在非接触模式下运行时的情况，且圆形电容式降雨传感器在接触模式下运行时每单位雨水量的最大薄膜应力平均增加量比其在非接触模式下运行时小约20倍。这正是圆形接触模式电容式降雨传感器的优势所在。
