Abstract:This study focuses on influence of Reynolds number on characteristics of cavity flow using Particle Image Velocimetry (PIV). Results show that time-mean velocity fields display same structures at different Reynolds numbers, namely, main flow and backflow vortex structures. The maximum vorticity locates at the entrance corner, and high value vorticity gathers in the boundary separation zone. At the impinging corner, values of turbulent intensities and Reynolds stress reach maximum. The stream-wise lengths of high value zone of turbulent intensities and Reynolds stress increase with the increase of Reynolds number, but it is opposite to low value zone in the entrance corner. Distribution forms of characteristic parameter of longitudinal and vertical spectrum resemble each other at different Reynolds numbers. Variation of Reynolds number results into mixing range changes of backflow and characteristic changes of the incoming flow, which will influence the distribution of spectrum in the cavity.