At that fraction of theoretical, the efficiencies of optimized two phase turbines would be in the low 60 percent range with organic working fluids and in the mid 50 percent range with steam and water. The efficiencies with nitrogen and water and Refrigerant 22 were 86 percent of theoretical. The turbine efficiency was 0.55 with nitrogen and water of 0.02 quality and 94 m/s velocity, 0.57 with Refrigerant 22 of 0.27 quality and 123 m/s velocity, and 0.30 with steam and water of 0.27 quality and 457 m/s velocity. Tests of a 2-Stage, Axial-Flow, 2-Phase TurbineĪ two phase flow turbine with two stages of axial flow impulse rotors was tested with three different working fluid mixtures at a shaft power of 30 kW. Several unconventional fan and turbine arrangements are indicated and the applications of these arrangements are discussed. It also shows that significant efficiency gains could be obtained by using some of these techniques.Ī general representation for axial-flow fans and turbinesĪ general representation of fan and turbine arrangements on a single classification chart is presented that is made possible by a particular definition of the stage of an axial-flow fan or turbine. The study enables one to draw conclusions about the nature of the flowfield in the rotor tip region. Rotating frame five hole probe measurements as well as stationary frame phase averaged total pressure measurements downstream of a single stage turbine facility were taken. The current investigation is performed in the Axial Flow Turbine Research Facility (AFTRF) of the Pennsylvania State University. Lastly, the widely used concept of squealer tip is studied. Next, a very short winglet obtained by slightly extending the tip platform in the tangential direction is investigated. Coolant flow from a tip trench is used to counter the momentum of the leakage jet. Three tip desensitization techniques, both active and passive, are examined. The current study uses several concepts to reduce the severity of losses introduced by the leakage vortex. The leakage flow, mainly induced by the pressure differential across the rotor tip section, usually rolls into a stream-wise vertical structure near the suction side part of the blade tip. It is also responsible for up to a third of aerodynamic losses in a turbine stage.
The leakage flow near the tip of unshrouded rotor blades in axial turbines imposes significant thermal loads on the blade. Aerodynamic tip desensitization in axial flow turbines
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