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Investigations of Interaction of the Main Flow with Root and Tip Leakage Flows in an axial turbine Stage by Means of a Source/Sink Approach for a 3D Navier-Stokes Solver

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Journal of Thermal Science 2001年第3期10卷 198-204页

作者： PiotrLampart SergeyYershov 等 InstituteofFluidFlowMachinery PolishAcademyofSciencesGdanskPoland InstituteofMechanicalEngineeringP

The effect of interaction of the main flow with root and tip leakage flows on the performance of an high pressure (HP) stage of an impulse turbine is studied numerically. The flow in blade-to-blade channels and axial gaps is computed with the aid of a 3D Navier-Stokes solver FlowER. The numerical scheme is modified to include the source/sink-type boundary conditions in places at the endwalls referring to design locations of injection of leak- age and windage flows into, or extract from, the blade-to-blade passage. The turbine stage is computed in three configurations. First, computations are made without tip leakage and windage flows with source/sink slots closed. Second, tip leakage slots are open. Third, both tip leakage and windage flow slots are open, and the obtained flow characteristics including kinetic energy losses in the stage are compared so as to estimate the interaction of the main and leakage flows.

关键词： axial turbine high-pressure stage tip leakage windage flow stage losses.

An Innovative Passive Tip-Leakage Control Method for axial turbines:Basic Concept and Performance Potential

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Journal of Thermal Science 2007年第3期16卷 215-222页

作者： Markus Hamik Reinhard Willinger Institute for Thermodynamics and Energy Conversion Vienna University of TechnologyGetreidemarkt 9/302A-1060 ViennaAustria

The present paper introduces a new concept for passive turbine tip-leakage control. The basic idea of the method is the connection of the blade leading edge and the blade tip by an internal channel. Due to the difference between the stagnation pressure at the leading edge and the low pressure at the blade tip, a small amount of the working fluid is extracted from the blade passage. At the blade tip, a jet is injected roughly perpendicular to the tip gap flow driven by the blade pressure difference. It is proposed that the jet blocks at least a part of the tip gap flow. Since the tip-leakage losses are proportional to the tip gap mass flow rate, the tip injection results in a reduction of the associated losses. After the introduction of the concept, an analytical model is presented which describes the reduction of the tip gap discharge coefficient due to the tip injection. Furthermore, the analytical model is supported by the results of a preliminary CFD analysis. Finally, the potential of the efficiency improvement by the passive blade tip injection method is reported.

关键词： axial turbine tip-leakage flow blade tip injection efficiency

Aerodynamic and heat transfer performances of a highly loaded transonic turbine rotor with upstream generic rim seal cavity

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Propulsion and Power Research 2021年第4期10卷 317-331页

作者： Zakaria Mansouri Faculty of Engineering The University of NottinghamNottinghamUnited Kingdom ABYLSEN Sciences&Technologies Rhône-Alpes Grenoble38000France

In turbine disk cavity,rim seals are fitted between the stator and its adjacent rotor disk.A coolant air injected through the turbine disk cavity to prevent the ingress of mainstream hot *** purpose of this paper is to investigate numerically the effect of the upstream purge flow on the aero and thermal performances of a high pressure turbine *** investigations are conducted on a generic rim seal cavity inspired from a realistic turbofan *** purge fractions(PF)equal to 0.2%,0.5%,1.0%and 1.5%of the mainstream are *** simulations are done by solving the three-dimensional Reynolds averaged Navier-Stokes and energy transport *** results include the effect of the PF on the cooling effectiveness,the sealing effectiveness,the secondary flows with losses and the heat transfer behavior,within the cavity and across the rotor *** low PF of 0.2%provided a low cooling effectiveness,a moderate sealing effectiveness and minimum *** high PF of 1.5%gave a high cooling effectiveness,a best sealing effectiveness and maximum *** medium PF of 1.0%supplied a compromise between the aerodynamic and thermal design needs with good cooling and sealing efficiencies and a tolerable level of losses.

关键词： axial turbine Thermal characteristics Aerodynamic losses Generic cavity Purge flow Rim seal Numerical simulation

Control of LP turbine Rotor Blade Underloading Using Stator Blade Compound Lean at Root

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Journal of Thermal Science 2000年第2期9卷 115-121页

作者： Piotr Lampart (Institute of Fluid Flow Machinery, Polish Academy of Sciences, Gdansk, Poland) Institute of Fluid Flow Machinery Polish Academy of Sciences Gdansk Poland

Due to a large gradient of reaction, LP rotor blades remain underloaded at the root over some range of volumetric flow rates. An interesting design to control the flow through the root passage of the overloaded stator and underloaded moving blade row is compound lean at the root of stator blades. The paper describes results of numerical investigations from a 3D NS solver FlowER conducted for several configurations of stator blade compound lean. The computations are carried out for a wide range of volumetric flow rates, accounting for the nominal operating regime as well as low and high load. It is found that compound lean induces additional blade force, streamwise curvature and redistribution of flow parameters in the stage, including pressure and mass flow rate spanwise that can improve the flow conditions in both the stator and the rotor. The obtained efficiency improvements depend greatly on the flow regime, with the highest gains in the region of low load.

关键词： axial turbine low-pressure stage stage losses separation shock wave compound lean