Experimental Measurements of Ingestion Through Turbine Rim Seals: Part 3—Single and Double Seals

2012 ◽  
Author(s):  
Carl M. Sangan ◽  
James A. Scobie ◽  
J. Michael Owen ◽  
Oliver J. Pountney ◽  
Mike Wilson ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Experimental Measurements ◽  
Pressure Measurements ◽  
Turbine Stage ◽  
Research Facility ◽  
Three Dimensional Flow ◽  
Co2 Gas ◽  
Performance Limit ◽  
Gas Concentration ◽  
Hot Gas

This paper describes experimental results from a research facility which experimentally models hot gas ingress into the wheel-space of an axial turbine stage. Measurements of CO2 gas concentration in the rim-seal region and inside the wheel-space are used to assess the performance of generic (though engine-representative) single and double seals in terms of the variation of concentration effectiveness with sealing flow rate. The variation of pressure in the turbine annulus, which governs externally-induced ingress, was obtained from steady pressure measurements downstream of the vanes. The benefit of using double seals is demonstrated: the ingested gas is shown to be predominately confined to the outer wheel-space radially outward of the inner seal; in the inner wheel-space, radially inward of the inner seal, the effectiveness is shown to be significantly higher. Criteria for ranking the performance of single and double seals are proposed, and the performance limit for any double seal is shown to be one in which the inner seal is exposed to rotationally-induced ingress. Although the ingress is a consequence of an unsteady, three-dimensional flow field and the cause-effect relationship between pressure and the sealing effectiveness is complex, the experimental data is shown to be successfully calculated by simple effectiveness equations developed from a theoretical model. The data illustrate that, for similar turbine-stage velocity triangles, the effectiveness can be correlated using two empirical parameters. In principle, these correlations could be extrapolated to a geometrically-similar turbine operating at engine-representative conditions.

Experimental Measurements of Ingestion Through Turbine Rim Seals—Part III: Single and Double Seals

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Carl M. Sangan ◽  
Oliver J. Pountney ◽  
James A. Scobie ◽  
Mike Wilson ◽  
J. Michael Owen ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Experimental Measurements ◽  
Pressure Measurements ◽  
Turbine Stage ◽  
Research Facility ◽  
Three Dimensional Flow ◽  
Co2 Gas ◽  
Performance Limit ◽  
Gas Concentration ◽  
Hot Gas

This paper describes experimental results from a research facility, which experimentally models hot gas ingress into the wheel-space of an axial turbine stage. Measurements of CO2 gas concentration in the rim-seal region and inside the wheel-space are used to assess the performance of generic (though engine-representative) single and double seals in terms of the variation of concentration effectiveness with sealing flow rate. The variation of pressure in the turbine annulus, which governs externally induced ingress, was obtained from steady pressure measurements downstream of the vanes. The benefit of using double seals is demonstrated: the ingested gas is shown to be predominately confined to the outer wheel-space radially outward of the inner seal; and in the inner wheel-space, radially inward of the inner seal, the effectiveness is shown to be significantly higher. Criteria for ranking the performance of single and double seals are proposed, and the performance limit for any double seal is shown to be one in which the inner seal is exposed to rotationally induced ingress. Although the ingress is a consequence of an unsteady, three-dimensional flow field and the cause-effect relationship between pressure and the sealing effectiveness is complex, the experimental data is shown to be successfully calculated by simple effectiveness equations developed from a theoretical model. The data illustrate that, for similar turbine-stage velocity triangles, the effectiveness can be correlated using two empirical parameters. In principle, these correlations could be extrapolated to a geometrically similar turbine operating at engine-representative conditions.

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

2011 ◽  
Author(s):  
Carl M. Sangan ◽  
Kunyuan Zhou ◽  
J. Michael Owen ◽  
Oliver J. Pountney ◽  
Mike Wilson ◽  
...  
Keyword(s):  
Three Dimensional ◽  
External Pressure ◽  
Operating Conditions ◽  
Turbine Stage ◽  
Research Facility ◽  
Three Dimensional Flow ◽  
Co2 Gas ◽  
Gas Concentration ◽  
Hot Gas ◽  
New Research

This paper describes a new research facility which experimentally models hot gas ingestion into the wheel-space of an axial turbine stage. Measurements of CO2 gas concentration in the rim-seal region and inside the cavity are used to assess the performance of two generic (though engine-representative) rim-seal geometries in terms of the variation of concentration effectiveness with sealing flow rate. The variation of pressure in the turbine annulus, which governs this externally-induced (EI) ingestion, was obtained from steady pressure measurements downstream of the vanes and near the rim seal upstream of the rotating blades. Although the ingestion through the rim seal is a consequence of an unsteady, three-dimensional flow field and the cause-effect relationship between pressure and the sealing effectiveness is complex, the experimental data is shown to be successfully calculated by simple effectiveness equations developed from a previously published orifice model. The data illustrate that, for similar turbine-stage velocity triangles, the effectiveness can be correlated using a non-dimensional sealing parameter, Φo. In principle, and within the limits of dimensional similitude, these correlations should apply to a geometrically-similar engine at the same operating conditions. Part 2 of this paper describes an experimental investigation of rotationally-induced (RI) ingress, where there is no mainsteam flow and consequently no circumferential variation of external pressure.

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

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Carl M. Sangan ◽  
Oliver J. Pountney ◽  
Kunyuan Zhou ◽  
Mike Wilson ◽  
J. Michael Owen ◽  
...  
Keyword(s):  
Three Dimensional ◽  
External Pressure ◽  
Operating Conditions ◽  
Turbine Stage ◽  
Three Dimensional Flow ◽  
Co2 Gas ◽  
Gas Concentration ◽  
Hot Gas ◽  
Mainstream Flow ◽  
New Research

This paper describes a new research facility which experimentally models hot gas ingestion into the wheel-space of an axial turbine stage. Measurements of the CO2 gas concentration in the rim-seal region and inside the cavity are used to assess the performance of two generic (though engine-representative) rim-seal geometries in terms of the variation of concentration effectiveness with sealing flow rate. The variation of pressure in the turbine annulus, which governs this externally-induced (EI) ingestion, was obtained from steady pressure measurements downstream of the vanes and near the rim seal upstream of the rotating blades. Although the ingestion through the rim seal is a consequence of an unsteady, three-dimensional flow field and the cause-effect relationship between the pressure and the sealing effectiveness is complex, the experimental data is shown to be successfully calculated by simple effectiveness equations developed from a previously published orifice model. The data illustrate that, for similar turbine-stage velocity triangles, the effectiveness can be correlated using a nondimensional sealing parameter, Φo. In principle, and within the limits of dimensional similitude, these correlations should apply to a geometrically-similar engine at the same operating conditions. Part II of this paper describes an experimental investigation of rotationally-induced (RI) ingress, where there is no mainstream flow and consequently no circumferential variation of external pressure.

Influence of Leakage Flows on Hot Gas Ingress

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Marios Patinios ◽  
Irvin L. Ong ◽  
James A. Scobie ◽  
Gary D. Lock ◽  
Carl M. Sangan
Keyword(s):  
Flow Structure ◽  
Turbine Stage ◽  
Co2 Gas ◽  
Gas Concentration ◽  
Leakage Flows ◽  
Hot Gas ◽  
Interface Gaps ◽  
Axial Clearance ◽  
Pass Through ◽  
Do So

One of the most important problems facing gas turbine designers today is the ingestion of hot mainstream gases into the wheel-space between the turbine disk (rotor) and its adjacent casing (stator). A rim seal is fitted at the periphery and a superposed sealant flow—typically fed through the bore of the stator—is used to prevent ingress. The majority of research studies investigating ingress do so in the absence of any leakage paths that exist throughout the engine's architecture. These inevitable pathways are found between the mating interfaces of adjacent pieces of hardware. In an environment where the turbine is subjected to aggressive thermal and centrifugal loading, these interface gaps can be difficult to predict and the resulting leakage flows which pass through them even harder to account for. This paper describes experimental results from a research facility which experimentally models hot gas ingestion into the wheel-space of an axial turbine stage. The facility was specifically designed to incorporate leakage flows through the stator disk; leakage flows were introduced axially through the stator shroud or directly underneath the vane carrier ring. Measurements of CO2 gas concentration, static pressure, and total pressure were used to examine the wheel-space flow structure with and without ingress from the mainstream gas-path. Data are presented for a simple axial-clearance rim-seal. The results support two distinct flow-structures, which are shown to be dependent on the mass-flow ratio of bore and leakage flows. Once the leakage flow was increased above a certain threshold, the flow structure is shown to transition from a classical Batchelor-type rotor-stator system to a vortex-dominated structure. The existence of a toroidal vortex immediately inboard of the outer rim-seal is shown to encourage ingestion.

Performance of a Finned Turbine Rim Seal

2014 ◽  
Author(s):  
Carl M. Sangan ◽  
James A. Scobie ◽  
J. Michael Owen ◽  
Gary D. Lock ◽  
Kok Mun Tham ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Turbine Stage ◽  
Research Facility ◽  
Flow Rates ◽  
Co2 Gas ◽  
Gas Concentration ◽  
Solid Body Rotation ◽  
Turbine Disc ◽  
Purge Flow ◽  
Improved Performance

In gas turbines, rim seals are fitted at the periphery of the wheel-space between the turbine disc and its adjacent casing; their purpose is to reduce the ingress of hot mainstream gases. A superposed sealant flow, bled from the compressor, is used to purge the wheel-space or at least dilute the ingress to an acceptable level. The ingress is caused by the circumferential variation of pressure in the turbine annulus radially outward of the seal. Engine designers often use double rim seals where the variation in pressure is attenuated in the outer wheel-space between the two seals. This paper describes experimental results from a research facility which models an axial turbine stage with engine-representative rim seals. The radial variation of CO2 gas concentration, swirl and pressure, in both the inner and outer wheel-space, are presented over a range of purge flow rates. The data are used to assess the performance of two seals: a datum double-rim seal and a derivative with a series of radial fins. The concept behind the finned seal is that the radial fins increase the swirl in the outer wheel-space; measurements of swirl show the captive fluid between the fins rotate with near solid body rotation. The improved attenuation of the pressure asymmetry, which governs the ingress, results in an improved performance of the inner geometry of the seal. The fins also increased the pressure in the outer wheel-space and reduced the ingress though the outer geometry of the seal.

Influence of Leakage Flows on Hot Gas Ingress

2018 ◽  
Author(s):  
Marios Patinios ◽  
Irvin L. Ong ◽  
James A. Scobie ◽  
Gary D. Lock ◽  
Carl M. Sangan
Keyword(s):  
Flow Structure ◽  
Turbine Stage ◽  
Co2 Gas ◽  
Gas Concentration ◽  
Leakage Flows ◽  
Hot Gas ◽  
Interface Gaps ◽  
Axial Clearance ◽  
Pass Through ◽  
Do So

One of the most important problems facing gas turbine designers today is the ingestion of hot mainstream gases into the wheel-space between the turbine disc (rotor) and its adjacent casing (stator). A rim seal is fitted at the periphery and a superposed sealant flow — typically fed through the bore of the stator — is used to prevent ingress. The majority of research studies investigating ingress do so in the absence of any leakage paths that exist throughout the engine’s architecture. These inevitable pathways are found between the mating interfaces of adjacent pieces of hardware. In an environment where the turbine is subjected to aggressive thermal and centrifugal loading these interface gaps can be difficult to predict and the resulting leakage flows which pass through them even harder to account for. This paper describes experimental results from a research facility which experimentally models hot gas ingestion into the wheel-space of an axial turbine stage. The facility was specifically designed to incorporate leakage flows through the stator disc; leakage flows were introduced axially through the stator shroud or directly underneath the vane carrier ring. Measurements of CO2 gas concentration, static pressure and total pressure were used to examine the wheel-space flow structure with and without ingress from the mainstream gas-path. Data is presented for a simple axial-clearance rim-seal. The results support two distinct flow-structures, which are shown to be dependent on the mass-flow ratio of bore and leakage flows. Once the leakage flow was increased above a certain threshold, the flow structure is shown to transition from a classical Batchelor-type rotor-stator system to a vortex-dominated structure. The existence of a toroidal vortex immediately inboard of the outer rim-seal is shown to encourage ingestion.

Performance of a Finned Turbine Rim Seal

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Carl M. Sangan ◽  
James A. Scobie ◽  
J. Michael Owen ◽  
Gary D. Lock ◽  
Kok Mun Tham ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Turbine Disk ◽  
Turbine Stage ◽  
Research Facility ◽  
Flow Rates ◽  
Co2 Gas ◽  
Gas Concentration ◽  
Solid Body Rotation ◽  
Purge Flow ◽  
Improved Performance

In gas turbines, rim seals are fitted at the periphery of the wheel-space between the turbine disk and its adjacent casing; their purpose is to reduce the ingress of hot mainstream gases. A superposed sealant flow, bled from the compressor, is used to purge the wheel-space or at least dilute the ingress to an acceptable level. The ingress is caused by the circumferential variation of pressure in the turbine annulus radially outward of the seal. Engine designers often use double-rim seals where the variation in pressure is attenuated in the outer wheel-space between the two seals. This paper describes experimental results from a research facility that models an axial turbine stage with engine-representative rim seals. The radial variation of CO2 gas concentration, swirl, and pressure, in both the inner and outer wheel-space, are presented over a range of purge flow rates. The data are used to assess the performance of two seals: a datum double-rim seal and a derivative with a series of radial fins. The concept behind the finned seal is that the radial fins increase the swirl in the outer wheel-space; measurements of swirl show the captive fluid between the fins rotate with near solid body rotation. The improved attenuation of the pressure asymmetry, which governs the ingress, results in an improved performance of the inner geometry of the seal. The fins also increased the pressure in the outer wheel-space and reduced the ingress though the outer geometry of the seal.

Effect of Wake Passing on Unsteady Aerodynamic Performance in a Turbine Stage

2006 ◽  
Author(s):  
K. Yamada ◽  
K. Funazaki ◽  
K. Hiroma ◽  
M. Tsutsumi ◽  
Y. Hirano ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Suction Side ◽  
Turbine Stage ◽  
Three Dimensional Flow ◽  
Unsteady Aerodynamic ◽  
Unsteady Effect ◽  
Unsteady Rans ◽  
Wake Passing ◽  
Stage Efficiency

In the present work, unsteady RANS simulations were performed to clarify several interesting features of the unsteady three-dimensional flow field in a turbine stage. The unsteady effect was investigated for two cases of axial spacing between stator and rotor, i.e. large and small axial spacing. Simulation results showed that the stator wake was convected from pressure side to suction side in the rotor. As a result, another secondary flow, which counter-rotated against the passage vortices, was periodically generated by the stator wake passing through the rotor passage. It was found that turbine stage efficiency with the small axial spacing was higher than that with the large axial spacing. This was because the stator wake in the small axial spacing case entered the rotor before mixing and induced the stronger counter-rotating vortices to suppress the passage vortices more effectively, while the wake in the large axial spacing case eventually promoted the growth of the secondary flow near the hub due to the migration of the wake towards the hub.

Effect of Temperature Nonuniformity on Heat Transfer in an Unshrouded Transonic HP Turbine: An Experimental and Computational Investigation

2010 ◽  
Author(s):  
Imran Qureshi ◽  
Andy D. Smith ◽  
Kam S. Chana ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Test Facility ◽  
Effect Of Temperature ◽  
Inlet Temperature ◽  
Experimental Measurements ◽  
Turbine Stage ◽  
Cfd Simulations ◽  
Turbine Inlet

Detailed experimental measurements have been performed to understand the effects of turbine inlet temperature distortion (hot-streaks) on the heat transfer and aerodynamic characteristics of a full-scale unshrouded high pressure turbine stage at flow conditions that are representative of those found in a modern gas turbine engine. To investigate hot-streak migration, the experimental measurements are complemented by three-dimensional steady and unsteady CFD simulations of the turbine stage. This paper presents the time-averaged measurements and computational predictions of rotor blade surface and rotor casing heat transfer. Experimental measurements obtained with and without inlet temperature distortion are compared. Time-mean experimental measurements of rotor casing static pressure are also presented. CFD simulations have been conducted using the Rolls-Royce code Hydra, and are compared to the experimental results. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough UK. This is a short duration transonic facility, which simulates engine representative M, Re, Tu, N/T and Tg /Tw at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation temperature distortion generator, capable of simulating well-defined, aggressive temperature distortion both in the radial and circumferential directions, at the turbine inlet.

Experimental and Numerical Investigation of the Influence of Rotor Blades on Hot Gas Ingestion Into the Upstream Cavity of an Axial Turbine Stage

2000 ◽  
Author(s):  
Dieter Bohn ◽  
Bernd Rudzinski ◽  
Norbert Sürken ◽  
Wolfgang Gärtner
Keyword(s):  
Carbon Dioxide ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Positive Influence ◽  
Rotor Blades ◽  
Gas Concentration ◽  
Hot Gas ◽  
Carbon Dioxide Gas ◽  
Static Pressure Distribution ◽  
Nozzle Guide

The phenomenon of hot gas ingestion through turbine rim seals is experimentally and numerically investigated for a complete stage with nozzle guide vanes and uncooled helicopter turbine rotor blades. In the experimental part, two different geometrical rim seal configurations are examined: 1. a simple axial gap between rotor and stator disk and 2. an axial gap between the rotor disk and a rim seal lip at the periphery of the stator disk. The results obtained are compared to experiments carried out for the same geometry but without rotor blades. The influence of the presence of rotor blades on hot gas ingestion is examined for different parameters such as nondimensional seal flow rate, Reynolds number in the turbine annulus and rotational speed. For the determination of the sealing efficiency measurements of carbon dioxide gas concentration are carried out in the wheelspace. The static pressure distribution in the cavity is measured by means of pressure taps at the stator disk. It is shown that for configuration 1 the presence of rotor blades causes a considerable drop in sealing efficiency whereas for configuration 2 the sealing efficiency increases significantly. In the numerical part results of three-dimensional unsteady CFD calculations for configuration 2 are compared to steady calculations for the same configuration without blades. Predictions of hot gas ingestion and carbon dioxide gas concentration in the hub region and inside the cavity are presented. Special emphasis is put on unsteady effects arising from rotor movement. A local ingestion zone rotating at approximately half rotor speed is numerically predicted. As indicated by the experimental results the rotor blades have a positive influence on the predicted sealing efficiency.

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