Experimental Measurements of Ingestion Through Turbine Rim Seals: Part 1—Externally-Induced Ingress

Sangan, Carl M.; Zhou, Kaifeng; Owen, J. Michael; Pountney, Oliver J.; Wilson, Mike; Lock, Gary

doi:10.1115/gt2011-45310

Cited by 17 publications

(40 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is a significant result, as it shows that the simple orifice model from Owen [1] can qualitatively predict ingress not only to an upstream wheel-space where the externally-induced ingress is dominated by the steady-state pressure asymmetry from the vanes, but also downstream where ingress is the result of a less powerful driving mechanism. Figure 10 shows the effect of four flow coefficients, CF = 0, 0.24, 0.29, and 0.36, on the variation The experimental data are fitted with the theoretical effectiveness equations from Sangan et al [11] using the maximum likelihood method described by Zhou et al [12]. All sets of experimental measurements demonstrate good agreement with the theoretical values.…”

Section: Variation Of Concentration Effectiveness With Sealing Flowmentioning

confidence: 78%

“…For any value of Φ 0 , the effectiveness in the downstream wheel-space is higher than that upstream; this indicates a weaker driver for ingress downstream. The experimental data are fitted with the theoretical effectiveness equations from Sangan et al [11] using the maximum likelihood method described by Zhou et al [12]. All sets of experimental measurements demonstrate good agreement with the theoretical values.…”

Section: Variation Of Concentration Effectiveness With Sealing Flowmentioning

confidence: 96%

See 1 more Smart Citation

Performance of Rim-Seals in Upstream and Downstream Cavities over a Range of Flow Coefficients

Patinios

Scobie

Sangan

et al. 2017

IJTPP

View full text Add to dashboard Cite

This paper presents measurements of CO 2 concentration and pressure in a new, highly instrumented and versatile, 1.5-stage gas turbine facility. The rig, which has been specifically designed for investigations related to hot gas ingestion, features interchangeable rim-seals, blading configurations, and the capability to operate at a wide range of flow coefficients. The turbine section includes an upstream and a downstream wheel-space on either side of a rotor disc featuring turned blades. Measurements of CO 2 concentration and steady static pressure were used to assess the pressure field in the turbine annulus and to investigate the performance of a radial clearance rim seal in both wheel-spaces. The wealth of data presented will be of great significance for computational fluid dynamics (CFD) validation studies considering downstream cavities. Pressure measurements were made at various locations in the turbine annulus for a range of flow coefficients. In the annulus upstream of the rotor blades the square root of the peak-to-trough pressure difference was shown to increase linearly with the flow coefficient. The radial variation in concentration effectiveness in the upstream and downstream wheel-spaces is provided for a range of sealing flow rates at an operating point near the design condition for the stage. In both cases, the concentration on the stator walls was virtually invariant with the radius and equal to that in the rotating core. The results also showed that for the same effectiveness, a smaller value of non-dimensional sealing flow is required in the downstream wheel-space, indicating a weaker driver for ingress. Off-design measurements of the value of the sealing flow parameter when the concentration effectiveness is 95% in both wheel-spaces are also provided for a range of flow coefficients. In the upstream wheel-space, the sealing flow parameter, and hence ingress, is shown to increase linearly with flow coefficient and be proportional to the square root of the peak-to-trough difference of the circumferential pressure variation in the annulus. Downstream of the blades, both the sealing flow parameter and the square root of the peak-to-trough pressure difference reach a minimum near the operating point, indicating that ingress is affected by the vane pressure field immediately downstream of the seal clearance.

show abstract

Section: Variation Of Concentration Effectiveness With Sealing Flowmentioning

confidence: 78%

Section: Variation Of Concentration Effectiveness With Sealing Flowmentioning

confidence: 96%

Performance of Rim-Seals in Upstream and Downstream Cavities over a Range of Flow Coefficients

Patinios

Scobie

Sangan

et al. 2017

IJTPP

View full text Add to dashboard Cite

show abstract

“…The geometry (not to scale) and boundary conditions are illustrated in Figure 2 The model (including the vane and blade geometries) is based on the design of an experimental rig at the University of Bath described by Sangan et al 1 The rig contains 32 stator vanes and 41 rotor blades, however for simplicity a configuration of 32 vanes and 32 blades has been studied computationally. Hence, an 11.25 degree sector model is considered, having one vane and one blade in the mainstream annulus.…”

Section: Computational Modelmentioning

confidence: 99%

“…The study was carried out prior to an experimental investigation, to be reported elsewhere. 1,2 and the computed flow field information has been used to inform and interpret the experiments.…”

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:

Self Cite

View full text Add to dashboard Cite

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.

show abstract

“…Measured variation of sealing effectiveness " with È o for an axial clearance seal at the design condition 20. (Concentration measurements made on the stator surface at r/b ¼ 0.958 -see inset.…”

mentioning

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:

View full text Add to dashboard Cite

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.

show abstract

Experimental Measurements of Ingestion Through Turbine Rim Seals: Part 1—Externally-Induced Ingress

Cited by 17 publications

References 0 publications

Performance of Rim-Seals in Upstream and Downstream Cavities over a Range of Flow Coefficients

Performance of Rim-Seals in Upstream and Downstream Cavities over a Range of Flow Coefficients

Computation of ingestion through gas turbine rim seals

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

Contact Info

Product

Resources

About