Effects of Pre-Swirl Angle on Flow Characteristics of Pre-Swirl Nozzle

Experimental measurements and numerical simulations on the discharge coefficient of pre-swirl nozzles with pre-swirl angles 30°,25°,20° and 15°,respectively,were carried out under pressure ratio range 1.1~1.9.The effects of pressure ratio and pre-swirl angle on the velocity and flow angle at the nozzle inlet and outlet,discharge coefficient and pre-swirl effectiveness were investigated via CFD work.Experiment and CFD results of discharge coefficient coincide well with each other.Data show that the discharge coefficient and pre-swirl effectiveness increase with the increase of pressure ratio.It is observed that the decrease of pre-swirl angle will lead to an almost unchanged discharge coefficient,while the pre-swirl effectiveness raises remarkably because of decreasing flow exit angle,with a maximal increase of 10%.