自然对流对气流式角速度传感器的影响

Effect of Natural Convection on the Gas-flow Angular Rate Sensor

解释了自然对流对气流式角速度传感器的影响机理。利用ANSYS-FLOTRAN CFD软件,通过建模、划分网格、加载和求解等途径,计算了在输入不同角速度时气流式角速度敏感元件内的流场。结果表明,由于自然对流的存在,无角速度输入时两热电阻丝处的气流速度之差Δv随倾斜角的不同发生改变,检测电桥输出一个零位电压ΔU,平均绝对偏差为16 mV,在传感器灵敏度为40 mV.[(°)/s]-1时,误差达到0.4(°)/s,导致零位重复性变差;由于自然对流的存在,有角速度输入时两热电阻丝处的气流速度之差Δv也随倾斜角的不同发生,不同角速度情况下,不同倾斜角引起的检测电桥电压ΔU平均相对偏差为2.4%,误差达到0.03(°)/s,引起灵敏度不稳定;自然对流对气流式角速度传感器的零位重复性的影响较大,对灵敏度的稳定性影响较小。该文为消除自然对流对气流式角速度传感器的影响,提高传感器的零位重复性和灵敏度的稳定性提供了理论和实验依据。

In this paper, the effect mechanism from natural convection on the gas-flow angular rate sensor is discussed. Using ANSYS-FLOTRAN CFD program, the stream field of gas in gas-flow angular rate sensing element on inputting different angular rate has been obtained by a series of procedure,such as model building, meshing,loading and equation solving. The results show that in existence of the natural convection, when there is no inputting angular rate,the velocity difference △v of gas flow at both hot wires will change with the tilt angle, the detection result is that the Bridge outputs a zero voltage. In the static status, the velocity of gas flow shows a symmetry distribution through central axis of enclosure,the fluid velocity at both hot wires is equal,so the current of both hot wires are also equal. The output of the Bridge circuit is zero △U,and the mean absolute error is 16my,when sensors sensitivity is 40 mV · [（°）/s]^-1 ,error is up to 0.4（°）/s,leading to worse zero reproducibility. In existence of natural convection,when there is an inputting angular rate , the velocity differenceAv of gas flow at both hot wires will also change with the tilt angle, different tilt angles make the mean comparative error of detecting Bridge voltage △U reach 2.4 % and the error get to 0.03（°）/s with the different angular rate,so leading to the instability of sensibility. The natural convection has a great influence on the gas-flow angular rate sensor＇s zero reproducibility and a small one on the stability of sensitivity. In this paper, both the theory and experiment foundation have been given in order to eliminate the influence of natural convection on the gas-flow angular rate sensor and to improve sensor＇s zero reproducibility as well as the stability of sensitivity.