Analysis of the measurement error in the cross section perpendicular to flow using 2D-PIV

As an important means of field testing,conventional two dimensional Particle Im-age Velocimetry (2D-PIV)has been widely applied to various flow measurements.Measurement error arises when 2D-PIV is applied to measure the cross section perpendicular to the flow due to geometric perspective relations.The error factors are analyzed and a model of the error in the measurement plane is established.The correctness of the error model is verified by experimental tests .It is concluded that the normal speed and off-axis angle of view are the key influencing fac-tors.The calculation results show that the maximum perspective error can be up to 9 .3%of nor-mal speed.According to the analysis of error model,the effect of perspective error on measure-ment of streamwise vortex flow field mainly exhibits in three aspects:changing the velocity value of flow field,changing the shape of vortex,and changing the position of the vortex.Finally, some approaches to reduce the error are proposed,which can improve the measurement for the application of 2D-PIV in the cross section perpendicular to the flow.