Experimental Investigations On The Characteristics Of Turbine Cascades

For the purpose of studying the formation and propagation of secondary flow vortices structure,the flow field around rectilinear turbine cascades have been probed in detail.This experiment is conducted in a low-speed cascade wind tunnel. Firstly,for the purpose of its symmetry and periodicity,the test equipment is altered; in order to acquire the nature of wind tunnel wall characteristics,thicknesses of cascades inlet boundary layers are surveyed.Secondly,the flow over blade surfaces and endwall surfaces are visualized by using thread at different Re and different incidence angles,the phenomena can be observed intuitively;the static pressures are taken on the suction and pressure surfaces by a"U"multiple-water-column manometer,four types of complication are taken into account.Finally,the measurements of velocity are taken at various axial planes within and downstream of the cascades by PIV,five instantaneous entire velocity fields along blade height and outlet plane are acquired.As a result,it is beneficial to optimize the blade flow field.In summary,PIV is a whole-field laser measurement technique,which can give the particularly instantaneous on-line velocity distribution;it has been widely employed to investigate the complicated internal flow fields in turbomachinery.