Effect And Correction Of Natural Wind On The Aerodynamic Coefficients Of Structures Measuring By Transiting Test

Structural aerodynamic coefficient transiting test method is a new test method for measuring the aerodynamic performance of structures using the wind of a driving car.This method can be applied to aerodynamic research,design and manufacturing of bridges,high-rise buildings,long-span structures,transportation facilities,wind turbines,automobiles,environmental engineering and so on.In addition to wind tunnel tests,numerical models and field measurements,the transiting test offers a new attempt and option for structural wind engineering and aerodynamic research.However,the transiting test method is also vulnerable to external conditions such as natural wind.Therefore,it is of great significance to study the influence of natural wind on structural aerodynamic coefficient transiting test methods and modify it for improving the accurate of transiting tests.Based on the wind pressure coefficient test of CAARC building model and the aerodynamic coefficient test of triangular prismatic structure,this thesis introduces the natural wind measurement system on the basis of the original test study of transiting test,studies the effect and correction of natural wind on the test result of transiting test,refines the transiting test method and provides guidance and recommendations for the subsequent test study of transiting test.Firstly,based on the building wind pressure coefficient transiting test,the effect of natural wind was studied.The natural wind which is a single variable factor is measured by the ultrasonic anemometer at a fixed location,and mean wind pressure coefficient and the fluctuating wind pressure coefficient are used to qualitatively and quantitatively describe the influence of natural wind on the CAARC building wind pressure coefficient transiting test.The results show that the excessive natural wind disturbs the turbulent characteristics of the car’s driving wind field.When the natural wind is in the range of 0-3.0 m/s,the average wind pressure coefficient is less affected,and the pulsating wind pressure coefficient is greatly affected,and the influence of the natural wind less than 1.66 m/s is limited and can be neglected within a certain error range.It is recommended that the CAARC wind pressure coefficient transiting test should be carried out when the natural wind is less than 1.66 m/s.Secondly,based on the structural aerodynamic coefficient transiting test,the effect of natural wind was studied.The natural wind which is a single variable factor is measured by the ultrasonic anemometer at a fixed location.The results of force and pressure measurements are used to qualitatively and quantitatively describe and explain the effect of natural wind on the aerodynamic coefficient of the triangular prism in transiting test.The results show that the driving wind field of vehicle,aerodynamic force coefficient and aerodynamic pressure coefficient are significantly influenced by the strong natural wind greater than 1.71 m/s,which can not be ignored;the influence of the natural wind less than1.71 m/s is limited and can be neglected within a certain error range.In addition,the natural wind has no influence on the trend of the pressure coefficient curve of the measuring point,and the natural wind has less influence on the positive pressure area of the windward side,which is lower than the negative pressure area of the leeward side.It is recommended that the structure aerodynamic coefficient sports car test be conducted under the condition that the natural wind is less than 1.71 m/s to improve the accuracy of the test results.Finally,based on the analysis of the results of the building wind pressure coefficient transiting test and the structural aerodynamic coefficient transiting test results with natural wind,the method of two measurements in both directions is proposed to modify the effect of natural wind on transiting tests.The impact on transiting tests with windward and leeward was analyzed and compared under different natural wind conditions.The results show that this correction method has certain feasibility for correcting the influence of natural wind,which can reduce the influence of natural wind on transiting tests,and improve the accuracy and provide guidance for subsequent transiting tests.