2009 · 12 citations · 0 references
EngineeringAerospace EngineeringAerodynamicsComputational Fluid DynamicsFluid DynamicsComputational AerodynamicsEngine Performance CharacteristicsNozzle DesignNozzle FlowTurbofan EnginesWind Turbine TechnologyMaximum FlowMaximum Flow RateNozzle GeometryTurbine EfficiencyTurbine OperationTurbine PerformanceVariable Geometry NozzlesVariable Geometry Turbines
A meanline model of a radial inflow turbine with a variable geometry nozzle is presented. The existence of a clearance gap in a variable geometry nozzle presents a significant challenge in the prediction of turbine performance. First, the nozzle clearance carries a portion of the flow that is not turned by the nozzle vanes. The amount of flow in the clearance region is related to the size of the clearance as well as the nozzle setting angle or the throat area. This under-turned flow influences the power output and turbine efficiency. Furthermore, the maximum flow rate that is allowed to pass the nozzle is increased because of the presence of the clearance, altering the turbine map in turbine operation.