Numerical study on the rotor solidity characteristics of axial turbine element stages

To explore the influence of the rotor solidity on the axial turbine element stage flow status and performance,unsteady numerical simulations on the turbine element stages with five different rotor solidity were conducted,and the rotor solidity influence on the element stage reaction,blade inlet and outlet flow angles,stator and rotor flow fields and loss status was investigated.The research results indicate that the effects of the rotor solidity alteration on the turbine element stage flow status and performance are directly associated with the stator solidity.When the stator solidity remains constant,The rotor solidity alteration changes the turbine element stage reaction by changing the mass flow rate through the element stage.As the rotor solidity increased to a certain extent,shocks will arise from the excessive expansion and acceleration of the gas flow in the stator region,as well as the flow separation caused by the shock interaction with the boundary layer.As the rotor solidity reduced to a certain extent,an large positive flow incidence will occur at the rotor inlet and cause a great range of flow separation on the rotor suction side.When the stator solidity remains constant,there's one best rotor solidity,resulting in the best turbine element stage performance.