3D CFD Ingestion Evaluation of a High Pressure Turbine Rim Seal Disk Cavity

Mirzamoghadam, A. V.; Heitland, G.; Morris, Mark C.; Smoke, J.; Malak, M.; Howe, Jack C.

doi:10.1115/gt2008-50531

Cited by 18 publications

(6 citation statements)

References 4 publications

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“…Mirzamoghadam et al [9] reported 3D CFD computations for a full stage HP turbine rotor-stator wheelspace. Based on these computational results, they found that the asymmetrical annulus pressure can give rise to ingestion even at relatively high sealing flow rates.…”

Section: Ihtc15-8457mentioning

confidence: 99%

Effects of Ingestion on the Flow and Heat Transfer in a Rotor-Stator System

Wang¹,

Wilson²

2014

Proceedings of the 15th International Heat Transfer Conference

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Ingestion (or ingress) of hot mainstream gas into the wheel-spaces between the rotor and stator discs in the high pressure stages of gas turbines is one of the most important internal cooling problems for engine designers. A rim seal at the periphery of the wheel-space and a radial outflow of sealing air are used to reduce or prevent this damaging ingestion. The sealing air is also used for rotor disc cooling. In this paper, a simplified axisymmetric computational fluid dynamics (CFD) model of a gas turbine rotor-stator wheel-space is used to predict the effects of ingress on the flow and heat transfer. The steady flow computations are carried out using the CFD code ANSYS/CFX and the shear stress transport (SST) turbulence model. The rotational Reynolds number, inlet flow rates and thermal boundary settings are selected to represent the operating conditions of an ingress experimental rig, and comparisons are made between computations and measurements of heat transfer in the wheel-space. The computed heat transfer from the steady model (in terms of values of local Nusselt number on the rotor) is in broad agreement with measurements obtained using thermochromic liquid crystal in a transient experiment. Alternative wall-surface thermal boundary conditions are investigated in order to study the sensitivity of computed Nusselt numbers to these modelling assumptions.

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Section: Ihtc15-8457mentioning

confidence: 99%

Effects of Ingestion on the Flow and Heat Transfer in a Rotor-Stator System

Wang¹,

Wilson²

2014

Proceedings of the 15th International Heat Transfer Conference

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“…Zhou et al 3 reviewed previous computational studies related to ingress, including those by Hills et al, 4 Laskowski et al, 5 Rabs et al, 6 Johnson et al, 7 Wang et al, 8 Zhou et al 9 and Mirzamoghadam et al 10,11 A number of authors have noted that the statistical convergence for pressure variations in the annulus is more quickly and more easily obtained than the cooling effectiveness field in the wheel-space.…”

Section: Computational Fluid Dynamicsmentioning

confidence: 99%

Computational extrapolation of turbine sealing effectiveness from test rig to engine conditions

Teuber

Maltson

et al. 2012

Proceedings of the Institution of Mechanical Engineers, Part A:

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The commercial computational fluid dynamics code ANSYS CFX 12.1 has been employed to carry out unsteady Reynolds-averaged Navier-Stokes computations to investigate the fluid mechanics of two different rim-seal geometries in a three-dimensional model of a turbine stage. The mainstream annulus, seal and wheel-space geometries are based on an experimental test rig used at the University of Bath. The calculated peak-to-trough pressure difference in the annulus, which is the main driving mechanism for ingestion, is in good agreement with experimental measurements. There is also a good agreement between the computed and measured swirl ratios in the wheel-space. Computed values of concentration-based sealing effectiveness are obtained over a range of sealing flow rates for both an axial clearance and a radial clearance rim seal. A good agreement with gas concentration measurements is found for the axial clearance seal over a certain range of sealing flow rates. Some under-prediction of the amount of ingestion for the radial clearance seal is obtained. The computed mainstream pressure coefficient increases progressively with mainstream Mach number in moving from quasi-incompressible experimental rig conditions to the compressible flow conditions encountered in engines. It is shown that the minimum sealing flow rate required to prevent ingestion increases as mainstream Mach number increases. A scaling method is proposed to allow sealing flow rates to prevent ingestion obtained from low Mach number experiments to be extrapolated to engine-representative conditions.

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“…Owen et al also gave an overview of findings from previous computational studies, including those by Hills et al, 5 Laskowski et al, 6 Rabs et al, 7 Johnson et al, 8 Wang et al, 9 Zhou et al, 10 Lewis and Wilson 11 and Mirzamoghadam et al 12,13 Decisions on some of the modelling approaches employed in the present work were made taking these findings into consideration.…”

Section: Introductionmentioning

confidence: 99%

Computation of ingestion through gas turbine rim seals

Zhou

Wilson

Owen

et al. 2012

Proceedings of the Institution of Mechanical Engineers, Part G:

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Three-dimensional unsteady computational fluid dynamics is applied to the ingestion of fluid from a non-uniform mainstream annulus flow via a rim-seal into a rotor-stator wheel-space. The results provide understanding of the complex flow and information for the development of more efficient computational models and analytical 'orifice models'. The commercial computational fluid dynamics code CFX has been used to carry out unsteady Reynolds-averaged Navier-Stokes computations with an shear stress transport turbulence model. A scalar equation is employed to represent the seeded tracer gas that can be used in experiments to determine sealing effectiveness, and the variation of effectiveness with sealing flow rate is determined for a simple axial clearance seal and one combination of axial and rotational Reynolds numbers. The computational domain comprises one pitch in a row of stator vanes and rotor blades. The rotating blade is accounted for by a sliding interface between the stationary and rotating sections of the model, located downstream of the seal clearance. The unsteady computations confirm that the magnitude of the peak-to-trough pressure difference in the annulus is the principal driving mechanism for ingestion (or ingress) into the wheel-space. This pressure difference is used in orifice models to predict sealing effectiveness; its magnitude however depends on the locations in the annulus and the wheel-space that are chosen for its evaluation as well as the sealing flow rate. The computational fluid dynamics is used to investigate the appropriateness of the locations that are often used to determine the pressure difference. It is shown that maximum ingestion occurs when the static pressure peak produced by the vane combines with that produced by the blade, and that highly swirled ingested flow could contact both the stator and rotor disk when little sealing flow is provided. The relationships between the unsteady simulations and simplified, more computationally efficient steady computations are also investigated. For the system considered here, ingress is found to be dictated principally by the pressure distribution caused by the vane. The effect of the rotating blade on the pressure distribution in the annulus is investigated by comparing the unsteady results with those for steady models that do not involve a blade. It is found that the presence of the blade increases the pressure asymmetry in the annulus. Although the pressure asymmetry predicted by unsteady and steady models have a similar magnitude, the sealing effectiveness is over-predicted considerably for the corresponding steady model. If a 'thin seal' geometric approximation is used in the steady model, however, similar effectiveness results compared with the unsteady model may be obtained much more economically.

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3D CFD Ingestion Evaluation of a High Pressure Turbine Rim Seal Disk Cavity

Cited by 18 publications

References 4 publications

Effects of Ingestion on the Flow and Heat Transfer in a Rotor-Stator System

Effects of Ingestion on the Flow and Heat Transfer in a Rotor-Stator System

Computational extrapolation of turbine sealing effectiveness from test rig to engine conditions

Computation of ingestion through gas turbine rim seals

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