Flow characteristics of preswirl cavity and rotorstator cavity of a coverplate 45° preswirl system structure were studied experimentally. Static pressure distribution on the stator

total pressure distribution on the mid plane (z/S=0326) and variations of the flow resistance coefficient in cavity and prenozzle discharge coefficient were obtained under high rotation speed. The results show that the pressure distribution in cavity is affected by the flow distribution weakly. The turbulent flow parameter is one of the primary control parameters of flow characteristics. The flow structure in cavity is mainly divided into two parts

the free vortex structures of rotorstator cavity

and the recirculation and low pressure zones in preswirl cavity. The flow resistance coefficient of the cavity rise significantly with the increase of the turbulent flow parameter. The discharge coefficient of preswirl nozzle increases with the increasing pressure ratio of preswirl nozzle.