| In the process of designing and realizing high-performance turbulence probe by using highperformance MEMS pressure sensor,the traditional method is to use professional wind tunnel equipment to complete the wind tunnel calibration of each probe at the corresponding calibration point in batches.The main problem is the high cost.On this background,this paper designs and develops a miniature low turbulence desktop calibration wind tunnel for probe calibration application,which can effectively solve the problem of probe cost control.The main research contents are as follows:First,the structure and fixture design of desktop low turbulence wind tunnel;Through the index decomposition,the size and inner diameter of the fan in the power section,as well as the size of the stable section and the contraction section are determined.On this basis,the 3D modeling and design work of fan structure is completed by using CAD tools,and the 3D modeling and design work of power blade and guide vane shape is completed by using cfturbo.The design of honeycomb grid is completed.In addition,according to the requirements of the probe index,a 2-DOF,digital positioning probe clamp design was completed,which was used for the probe clamping and orientation automatic control in the probe calibration operation,and the design eliminated the error caused by the windward angle factor of the probe measurement.The second is the hydrodynamics simulation of desktop low turbulence wind tunnel;When the grid and contraction curve are determined,the simulation results show that the outlet air flow is uniform and the turbulence is small,which meets the design requirements.In order to ensure that the material selection of the power blade meets the structural safety requirements,the fluid structure coupling analysis of the resin material blade is carried out to determine that the selection of the resin material for the key power blade is safe and reliable.The third is the design of control system for desktop low turbulence wind tunnel;According to the operational requirements of wind tunnel,the low turbulence wind tunnel and fixture control system are designed and implemented.The control system of desktop low turbulence wind tunnel realizes the feedback control of wind speed quantitative output according to the air pressure sensor signal and motor speed signal;the fixture control system realizes the precise quantitative control of the windward angle(orientation,pitch)under the state of probe clamping.The automatic control target of calibration process is realized,and the operability of desktop low turbulence wind tunnel is improved.Fourth,prototype debugging and index verification;Through 3D printing,the power section,stable section and contraction section of the wind tunnel are made respectively,the whole culvert is assembled,and the test platform for calibration of the wind tunnel is built.The hot wire anemometer with high measurement accuracy and good repeatability is used for wind speed measurement,the flow field quality of the designed calibration wind tunnel is tested,and the dynamic pressure of different wind speeds is measured by BMP 180 air pressure sensor The dynamic pressure stability coefficient of the calibration wind tunnel is calculated and four sets of measurement data are given.The instantaneous value of the wind speed at the target point on the optimum measuring surface is measured,and the average value of the wind speed and the fluctuation amplitude of the air outlet are obtained by processing the test data.The test data show that the technical specifications of wind tunnel design have been achieved and meet the performance requirements of wind tunnel design. |
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