| Gas micro-flow control valves play an important role in aerospace,medical equipment,automation instruments and other fields.The continuous control function of the micro-flow gas is realized by adjusting the micro-flow control valve,which meets the continuous control demand for the gaseous microfluid flow.Conventional gaseous flow control valve for precise regulation is difficult to satisfy the requirements of the problem,and this paper designs a gas micro flow control valve based on the principle of compressible gas flow,and studies the valve core structure.The specific research contents are as follows:(1)The overall structure of gas micro flow control valve was designed and the contour curve of valve core is fitted.A piezoelectric-driven flow valve was designed,the structure and working principle of the flow valve were clarified.Analyze the force of the flow valve structure,and select the compression spring,piezoelectric element and sealing ring that meet the work requirements.In order to obtain linear flow characteristics,a mathematical model of the flow valve orifice is established.Based on the principle of gas flow,the formula for calculating the gas flow at the orifice of the flow valve is derived.Combined with the compressible gas state equation,deduce and calculate the spool contour curve of the gas micro-flow control valve,and different functions are used to fit the solution data to obtain the spool profile fitting function with high coefficient of determination.Use fluent numerical analysis,the flow field models under different spool profile fitting functions are simulated,and choose the polynomial fitting curve as the spool profile of the flow valve.(2)The influence of spool displacement on flow field performance of flow valve is analyzed,and the spool structure parameters of flow valve are optimized.Combined with digital modeling and simulation technology,the design theory of gas micro-flow control valve is verified.The influence of valve core displacement on the flow field characteristics such as pressure,velocity change and vortex strength in the valve cavity are analyzed.Aiming at reducing the unbalance force and vortex strength of valve core and improving the flow stability of flow valve,the influence of the structural parameters of valve core and valve seat on the flow field performance is analyzed across the board,and the optimized structural parameters are determined.Different structural parameters are selected as test points by the uniform test design method,and the test results are regression analyzed,the response function of multi-objective optimization is established and solved in order to determine the best parameters of flow valve spool structure.(3)The flow test platform of flow valve prototype is built and the flow test experiment is carried out.Select the processing materials of some parts of the flow valve microvalve,make the flow valve parts and complete the assembly work of the flow valve,and then fix it to the installation platform.Select the type of experimental equipment such as constant pressure pump,piezoelectric ceramic controller,gas flow meter,etc.,and connect the experimental equipment to complete the construction of the flow test platform of the flow valve prototype.The displacement characteristics of the selected piezoelectric ceramics are tested with a capacitance micrometer,and the relationship curve between the input voltage and the output displacement is obtained.The 40° cone spool is used to verify the displacement transmission capacity and air tightness of the overall structure of the flow valve prototype.Then test the output flow of the polynomial spool flow valve under different input displacements.The results show that the flow valve has the ability of realizing the on-off adjustment and continuous control of the gas micro-flow.In the case of large spool displacement,the flow increment of the polynomial spool is reduced by 74% compared with the cone spool,thus verifying the gas micro-flow control the effectiveness of the valve. |
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