Development And Performance Study Of Wind Tunnel Test System For Micro Aircraft

The micro aircraft has the advantages of good concealment,low aerodynamic noise and high maneuverability,and has broad development space and application prospects in the future,among which the design of aerodynamic performance has always been the focus and difficulty of micro aircraft research.Due to the large difference between the relevant aerodynamic characteristics of micro aircraft and conventional aircraft,a large number of unsteady aerodynamic theories will be used in the research process,so their aerodynamic performance can generally only be studied through experimental tests.The micro aircraft itself is small in size and light in weight,and the force generated during the movement is small,and it is difficult to measure it.Therefore,based on the existing micro aircraft,this paper designed a wind tunnel test system,the main work content is as follows:In order to meet the low flow rate and high quality flow field required for the test of micro aircraft,this paper developed a low-speed wind tunnel,which adopts straight-flow structure as a whole,and according to the relevant wind tunnel design theory,the wind tunnel sections including the power section are designed in detail,and the three-dimensional modeling of each section is completed by using CATIA software;at the same time,an ANSYS software was used to simulate the shrinkage section of the wind tunnel,and a reasonable shrinkage curve was selected according to the simulation results.In order to evaluate the flow field quality of the wind tunnel more accurately,the internal flow field of the wind tunnel was tested,and according to the test results,the flow field quality was analyzed from three aspects: the average wind speed of the center,the uniformity and turbulence degree of the flow field,and the stability of the air flow.The results show that the flow rate of the internal flow field of the wind tunnel is low,the uniformity of the flow field and the stability of the air flow are better,and the turbulence degree is also low,which can meet the requirements of the micro aircraft for the test flow field.Subsequently,this paper designed a small-scale three-component strain balance,which can be combined with low-speed wind tunnels to form a complete wind tunnel test system.According to the specific design requirements,This paper completes the selection of strain gauges,the selection of manufacturing materials,the determination of the measuring range and the design of the overall three-dimensional structure of the balance,and an ANSYS simulation software was used to complete the static simulation,strength verification and modal analysis of the overall structure of the strain balance.The simulation results show that the strength and natural frequency of the strain balance meet the design requirements,and the interdimensional coupling error is small,and the sensitivity of each component to the load is good,which can meet the design requirements.In order to further evaluate the overall performance of the strain balance,this paper carried out a static calibration test,in the data acquisition system built,uses the pulley loading weight method and the transformation attitude method to complete the static calibration of the strain balance,obtains the change image between the input and output on each component of the balance,and uses MATLAB software to perform the least squares fitting of the data,and obtains the fitting relationship between input and output.According to the calibration results,this paper calculated the calibration matrix and decoupling matrix of the strain balance,and studied and analyzed the performance of the strain balance from six aspects,including sensitivity,resolution,and interdimensional coupling error.The results show that the overall performance of the strain balance is better,with low interdimensional coupling error and higher sensitivity,which can meet the test requirements of micro aircraft.