Research On Liquid-Solid Contact Resistance Characteristics Of MHD Micro-angle Vibration Sensor

With the rapid development of aerospace technology,various types of space sensors are the hotspots of research,and the inertial elements used for inertial navigation put forward higher requirements for various accuracy.The micro-angle vibration sensor based on Magnetohydrodynamics(MHD)is an effective sensor that has been verified in space.It has the characteristics of wide frequency band,impact resistance,low noise and small size.Noise is the key technical indicator of the MHD micro-angle vibration sensor.The liquid-solid contact resistance between the conductive fluid and the fluid ring is the main source of noise.In order to improve the sensitivity of the sensor and reduce noise,it is necessary to carry out research on the characteristics of the liquid-solid contact resistance.Based on the working principle of the sensor and the mechanism of noise generation,this paper systematically analyzes the factors affecting the liquid-solid contact resistance and establishes a theoretical model of the liquid-solid contact resistance.A set of liquid-solid contact resistance measurement devices and are designed.Using this device test to quantify the influence of various factors on the liquid-solid contact resistance,which has a certain guiding significance for the design of MHD sensors.The specific work is as follows:(1)The formation mechanism of liquid-solid contact resistance on sensor noise is analyzed theoretically.Based on the Holm classic model theory,the theoretical model of the liquid-solid contact resistance of the MHD micro-angle vibration sensor is derived and established.The relationship between contact resistance and contact area,roughness,film,resistivity and conductive spot radius is derived.(2)On the basis of analyzing and summarizing the existing contact resistance test methods,the method of measuring liquid-solid contact resistance by the average difference method under oxygen-free conditions is proposed.The proposed method can eliminate and reduce the surface oxidation of conductive fluid,wire resistance and testing.A set of liquid-solid contact resistance measurement device was designed and built to realize accurate measurement.(3)Using the measuring device,the influence of contact area,roughness,film layer and temperature on liquid-solid contact resistance was explored.The results show that as the contact area increases,the liquid-solid contact resistance decreases and becomes stable.As the roughness and the thickness of the film increase,the liquid-solid contact resistance increases significantly and becomes unstable.As the temperature increases,the viscosity and resistivity of the conductive fluid are simultaneously affected and the result of mutual superposition makes the liquid-solid contact resistance slowly rise.The test results are consistent with the theoretical derivation.The research results of this paper can provide theoretical basis and data reference for the design of MHD micro-angle vibration sensor to reduce the liquid-solid contact resistance.