Author: Daryl Yao-Wah Lee
Publisher:
ISBN: 9781339544069
Category :
Languages : en
Pages :
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A computational fluid dynamics (CFD) procedure has been developed to predict the three-dimensional unsteady flow through a multi-stage axial turbine including the effects of heat transfer. This procedure simultaneously solves the unsteady Reynold's-averaged Navier-Stokes equations for the flow along with the heat conduction equation for the solid. Solution time is minimized through the use of multiple central processing units (CPUs).The blades of the multi-stage turbine move in time and the flow interacts with adjacent vane (stationary) passages through the use of a parallel, sliding-grid, inter-blade-row treatment. Described are the techniques used to solve the governing equations, the inter-blade-row treatment, and the parallelization of the overall approach. The uniqueness of this prediction method lies in the unsteady, multi-stage conjugate solution and the use of multiple combined cores. The approach is validated for the High Impact Technology Turbine designed and tested at the Air Force Research Laboratory.
Author: Vikram Shyam
Publisher: BiblioGov
ISBN: 9781289035730
Category :
Languages : en
Pages : 42
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Unsteady 3-D RANS simulations have been performed on a highly loaded transonic turbine stage and results are compared to steady calculations as well as to experiment. A low Reynolds number k-epsilon turbulence model is employed to provide closure for the RANS system. A phase-lag boundary condition is used in the tangential direction. This allows the unsteady simulation to be performed by using only one blade from each of the two rows. The objective of this work is to study the effect of unsteadiness on rotor heat transfer and to glean any insight into unsteady flow physics. The role of the stator wake passing on the pressure distribution at the leading edge is also studied. The simulated heat transfer and pressure results agreed favorably with experiment. The time-averaged heat transfer predicted by the unsteady simulation is higher than the heat transfer predicted by the steady simulation everywhere except at the leading edge. The shock structure formed due to stator-rotor interaction was analyzed. Heat transfer and pressure at the hub and casing were also studied. Thermal segregation was observed that leads to the heat transfer patterns predicted by steady and unsteady simulations to be different.
Author: Vikram Shyam
Publisher:
ISBN:
Category :
Languages : en
Pages : 121
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Abstract: This is the first 3-D unsteady RANS simulation of a highly loaded transonic turbine stage and results are compared to steady calculations and experiments. A low Reynolds number [kappa]-[epsilon] turbulence model is employed to provide closure for the RANS system. Phase-lag is used in the tangential direction to account for stator-rotor interaction. Due to the highly loaded characteristics of the stage, inviscid effects dominate the flowfield downstream of the rotor leading edge minimizing the effect of segregation to the leading edge region of the rotor blade. Unsteadiness was observed at the tip surface that results in intermittent 'hot spots'. It is demonstrated that unsteadiness in the tip gap is governed by both inviscid and viscous effects due to shock-boundary layer interaction and is not heavily dependent on pressure ratio across the tip gap. This is contrary to published observations that have primarily dealt with subsonic tip flows. The high relative Mach numbers in the tip gap lead to a choking of the leakage flow that translates to a relative attenuation of losses at higher loading. The efficacy of a new tip geometry is discussed to minimize heat flux at the tip while maintaining choked conditions. Simulated heat flux and pressure on the blade and hub agree favorably with experiment and literature. The time-averaged simulation provides a more conservative estimate of heat flux than the steady simulation. The shock structure formed due to stator-rotor interaction is analyzed. A preprocessor has also been developed as a conduit between the unstructured multi-block grid generation software GridPro and the CFD code TURBO.
Author: Douglas L. Sondak
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: John J. Adamczyk
Publisher:
ISBN:
Category : Blades
Languages : en
Pages : 0
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1042
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 312
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Author: Douglas L. Sondak
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: John J. Adamczyk
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Author: Natalia V. Smelova
Publisher:
ISBN:
Category : Air flow
Languages : en
Pages : 236
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