Prediction of Ingestion Through Turbine Rim Seals—Part I: Rotationally Induced Ingress

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Flow Rate ◽  
Turbine Blades ◽  
External Pressure ◽  
Swirling Flows ◽  
Radial Gradient ◽  
Mainstream Flow ◽  
Predicted Values ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Good Agreement

The mainstream flow past the stationary nozzle guide vanes and rotating turbine blades in a gas turbine creates an unsteady nonaxisymmetric variation in pressure in the annulus, radially outward of the rim seal. The ingress and egress occur through those parts of the seal clearance where the external pressure is higher and lower, respectively, than that in the wheel-space; this nonaxisymmetric type of ingestion is referred to here as externally induced (EI) ingress. Another cause of ingress is that the rotating air inside the wheel-space creates a radial gradient of pressure so that the pressure inside the wheel-space can be less than that outside; this creates rotationally induced (RI) ingress, which—unlike EI ingress—can occur, even if the flow in the annulus is axisymmetric. Although the EI ingress is usually dominant in a turbine, there are conditions under which both EI and RI ingress are significant, these cases are referred to as combined ingress. In Part I of this two-part paper, the so-called orifice equations are derived for compressible and incompressible swirling flows, and the incompressible equations are solved analytically for the RI ingress. The resulting algebraic expressions show how the nondimensional ingress and egress vary with Θ0, which is the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. It is shown that ε, the sealing effectiveness, depends principally on Θ0, and the predicted values of ε are in mainly in good agreement with the available experimental data.

Prediction of Ingestion Through Turbine Rim Seals—Part 1: Rotationally-Induced Ingress

2009 ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Flow Rate ◽  
Swirling Flow ◽  
Turbine Blades ◽  
External Pressure ◽  
Radial Gradient ◽  
Mainstream Flow ◽  
Predicted Values ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Good Agreement

The mainstream flow past the stationary nozzle guide vanes and rotating turbine blades in a gas turbine creates an unsteady non-axisymmetric variation of pressure in the annulus radially outward of the rim seal. Ingress and egress occur through those parts of the seal clearance where the external pressure is higher and lower, respectively, than that in the wheel-space; this non-axisymmetric type of ingestion is referred to here as externally-induced (EI) ingress. Another cause of ingress is that the rotating air inside the wheel-space creates a radial gradient of pressure so that the pressure inside the wheel-space can be less than that outside; this creates rotationally-induced (RI) ingress, which — unlike EI ingress — can occur even if the flow in the annulus is axisymmetric. Although EI ingress is usually dominant in a turbine, there are conditions under which both EI and RI ingress are significant: these cases are referred to as combined ingress. In Part 1 of this two-part paper, the so-called orifice equations are derived for compressible and incompressible swirling flow, and the incompressible equations are solved analytically for RI ingress. The resulting algebraic expressions show how the nondimensional ingress and egress vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. It is shown that ε, the sealing effectiveness, depends principally on Θ0, and the predicted values of ε are in mainly good agreement with available experimental data. Part 2 (ASME GT2009-59122) concentrates on the solution and validation of the orifice equations for EI and combined ingress.

Experimental Measurements of Ingestion Through Turbine Rim Seals: Part 4 — Off-Design Conditions

2013 ◽  
Author(s):  
James A. Scobie ◽  
Carl M. Sangan ◽  
Roy Teuber ◽  
Oliver J. Pountney ◽  
J. Michael Owen ◽  
...  
Keyword(s):  
Large Deviation ◽  
Turbine Blades ◽  
Design Flow ◽  
Flow Coefficient ◽  
Turbine Stage ◽  
Mainstream Flow ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Experimental Rig ◽  
Good Agreement

This paper describes results obtained from an experimental facility which models ingress through the rim seal into the upstream wheel-space of an axial-turbine stage. The experimental rig included 32 nozzle guide vanes and 41 symmetrical turbine blades, and the paper presents measurements of ε (the sealing effectiveness) for single- and double-clearance seals for both over-speed (where the blades rotate faster than at the design point) and under-speed conditions. The design flow coefficient was CF = 0.538, and tests were conducted for 0 < CF < 0.9, which is larger than the range experienced in engines. The measured values of ε were correlated by the ‘effectiveness equations’ for rotationally-induced (RI) and externally-induced (EI) ingress. The correlated effectiveness curves were used to determine Φmin′ (the value of the sealing flow parameter when ε = 0.95), and the variation of Φmin′ with CF was in mainly good agreement with the theoretical curve for CI (combined ingress), which covered the transition from RI to EI ingress. Departure of the measured values of Φmin′ from the CI curve occurred at very low values of CF for all the seals tested; this was attributed to the effects of separation of the mainstream flow over the turbine blades at large ‘deviation angles’ between the flow and the blades. The measurements are expected to be qualitatively similar to but quantitatively different from those experienced in engines.

Prediction of Ingestion Through Turbine Rim Seals—Part II: Externally Induced and Combined Ingress

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Gas Turbines ◽  
Swirling Flows ◽  
Published Data ◽  
Flow Rates ◽  
Hot Gas ◽  
Predicted Values ◽  
Good Agreement

Ingress of hot gas through the rim seals of gas turbines can be modeled theoretically using the so-called orifice equations. In Part I of this two-part paper, the orifice equations were derived for compressible and incompressible swirling flows, and the incompressible equations were solved for axisymmetric rotationally induced (RI) ingress. In Part II, the incompressible equations are solved for nonaxisymmetric externally induced (EI) ingress and for combined EI and RI ingress. The solutions show how the nondimensional ingress and egress flow rates vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. For EI ingress, a “saw-tooth model” is used for the circumferential variation of pressure in the external annulus, and it is shown that ε, the sealing effectiveness, depends principally on Θ0; the theoretical variation of ε with Θ0 is similar to that found in Part I for RI ingress. For combined ingress, the solution of the orifice equations shows the transition from RI to EI ingress as the amplitude of the circumferential variation of pressure increases. The predicted values of ε for EI ingress are in good agreement with the available experimental data, but there are insufficient published data to validate the theory for combined ingress.

Prediction of Ingestion Through Turbine Rim Seals—Part 2: Externally-Induced and Combined Ingress

2009 ◽  
Author(s):  
J. Michael Owen
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Gas Turbines ◽  
Swirling Flow ◽  
Published Data ◽  
Flow Rates ◽  
Hot Gas ◽  
Predicted Values ◽  
Good Agreement

Ingress of hot gas through the rim seals of gas turbines can be modelled theoretically using the so-called orifice equations. In Part 1 (ASME GT 2009-59121) of this two-part paper, the orifice equations were derived for compressible and incompressible swirling flow, and the incompressible equations were solved for axisymmetric rotationally-induced (RI) ingress. In Part 2, the incompressible equations are solved for non-axisymmetric externally-induced (EI) ingress and for combined EI and RI ingress. The solutions show how the nondimensional ingress and egress flow rates vary with Θ0, the ratio of the flow rate of sealing air to the flow rate necessary to prevent ingress. For EI ingress, a ‘saw-tooth model’ is used for the circumferential variation of pressure in the external annulus, and it is shown that ε, the sealing effectiveness, depends principally on Θ0; the theoretical variation of ε with Θ0 is similar to that found in Part 1 for RI ingress. For combined ingress, the solution of the orifice equations shows the transition from RI to EI ingress as the amplitude of the circumferential variation of pressure increases. The predicted values of ε for EI ingress are in good agreement with available experimental data, but there are insufficient published data to validate the theory for combined ingress.

scholarly journals Wall-Modelled Large Eddy Simulations of Axial Turbine Rim Sealing

2020 ◽  
Author(s):  
Donato M. Palermo ◽  
Feng Gao ◽  
Dario Amirante ◽  
John W. Chew ◽  
Anna Bru Revert ◽  
...  
Keyword(s):  
Eddy Viscosity ◽  
Passive Scalar ◽  
Rotor Blades ◽  
Computational Time ◽  
Scalar Concentration ◽  
Large Eddy ◽  
Annulus Flow ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Good Agreement

Abstract This paper presents WMLES simulations of a chute type turbine rim seal. Configurations with an axisymmetric annulus flow and with nozzle guide vanes fitted (but without rotor blades) are considered. The passive scalar concentration solution and WMLES are validated against available data in the literature for uniform convection and a rotor-stator cavity flow. The WMLES approach is shown to be effective, giving significant improvements over an eddy viscosity turbulence model, in prediction of rim seal effectiveness compared to research rig measurements. WMLES requires considerably less computational time than wall-resolved LES, and has the potential for extension to engine conditions. All WMLES solutions show rotating inertial waves in the chute seal. Good agreement between WMLES and measurements for sealing effectiveness in the configuration without vanes is found. For cases with vanes fitted the WMLES simulation shows less ingestion than the measurements, and possible reasons are discussed.

Wall-Modelled Large Eddy Simulations of Axial Turbine Rim Sealing

2021 ◽  
Author(s):  
Donato Maria Palermo ◽  
Feng Gao ◽  
Dario Amirante ◽  
John W. Chew ◽  
Anna Bru Revert ◽  
...  
Keyword(s):  
Eddy Viscosity ◽  
Passive Scalar ◽  
Rotor Blades ◽  
Computational Time ◽  
Scalar Concentration ◽  
Large Eddy ◽  
Annulus Flow ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Good Agreement

Abstract This paper presents WMLES simulations of a chute type turbine rim seal. Configurations with an axisymmetric annulus flow and with nozzle guide vanes fitted (but without rotor blades) are considered. The passive scalar concentration solution and WMLES are validated against available data in the literature for uniform convection and a rotor-stator cavity flow. The WMLES approach is shown to be effective, giving significant improvements over an eddy viscosity turbulence model, in prediction of rim seal effectiveness compared to research rig measurements. WMLES requires considerably less computational time than wall-resolved LES, and has the potential for extension to engine conditions. All WMLES solutions show rotating inertial waves in the chute seal. Good agreement between WMLES and measurements for sealing effectiveness in the configuration without vanes is found. For cases with vanes fitted the WMLES simulation shows less ingestion than the measurements, and possible reasons are discussed.

scholarly journals Heat Transfer to Rotating Turbine Blades in a Flow Undisturbed by Wakes

1994 ◽  
Author(s):  
T. Garside ◽  
R. W. Moss ◽  
R. W. Ainsworth ◽  
S. N. Dancer ◽  
M. G. Rose
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbine Blades ◽  
Heat Fluxes ◽  
Reverse Direction ◽  
Similar Data ◽  
Blade Surface ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

The flow over the high pressure blades of a gas turbine is disturbed by wakes and shock waves from the nozzle guide vanes upstream. These disturbances lead to increased heat transfer to the blade surfaces, the accurate prediction of which is an essential stage in the design process. The Oxford Rotor experiment consists of a highly instrumented 0.5 m diameter shroudless turbine which is supplied with air from a piston tube during the 200 ms run time and simulates realistic engine Mach and Reynolds numbers. Previous experiments have measured blade surface pressures and heat transfer rates, and compared them with similar data from linear cascades. The present work is designed to enable the accuracy of rotation terms in computational fluid dynamics (CFD) calculations to be assessed, by providing heat transfer data from the rotating frame in the absence of wakes. Flow disturbances were avoided by removing the nozzle guide vanes, the correct angle of incidence onto the rotor blades being achieved by rotating the rotor in the reverse direction. Blade surface heat fluxes were measured using thin film gauges. In the absence of the usual blade-passing fluctuations, the root-mean-square fluctuation in heat flux was typically only 7% of the DC level. Nusselt numbers are compared with cascade data and CFD predictions from both a three-dimensional viscous Navier-Stokes equation solver and a two-dimensional boundary layer prediction. The low inlet turbulence level produced a long laminar region on the suction surface followed by sudden transition. CFD predictions of Nusselt number on this surface were very sensitive to the choice of boundary layer state, and the experimental level was approximately mid-way between predictions with a transitional intermittency distribution and those with a turbulent distribution. On the pressure surface the levels were approximately 25% below predicted levels, and possible reasons for this are considered.

scholarly journals Multi-Purpose Fuel: Problems That We Face

1969 ◽  
Author(s):  
John S. Siemietkowski
Keyword(s):  
Turbine Blades ◽  
Engine Performance ◽  
Problem Area ◽  
Turbine Engine ◽  
Short Period ◽  
Marine Diesel ◽  
Fuel Filter ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes ◽  
Cycle Endurance

A Pratt and Whitney FT4A Marine Gas Turbine Engine rated at 25,000 HP for a 100°F inlet day, was tested at the Naval Ship Engineering Center Philadelphia Division for a total of 201 hours, 15 minutes. The engine was subjected to an initial 30 hour “coking” run, conducted at 10,000 HP, 2380 rpm, to determine adverse effects on the engine under simulated destroyer type operation. Following the 30 hour coking run, the engine was subjected to a 150 hour cycle endurance operation. Salt was admitted to the inlet air. A combustion section inspection was performed at the end of the 30 hour coking run. No detrimental effects were noted at that time. An overall combustion section inspection was performed at the end of the test. A fuel manifold and nozzle spray check was performed with both acceptable for further use. First stage turbine blades showed some degree of sulfidation, while the nozzle guide vanes showed evidence of coating loss and partial penetration into the base metal (on only the uncoated vanes). The major problem area during the test was the failure of the coalescer fuel filter to function properly with Multi-Purpose fuel. Due to the higher pour point (with attendant “wax” precipitation) of the fuel in comparison with normal Marine Diesel (MIL-F-16884), plugging of the coalescer filter elements occurred in a very short period of time. Engine performance over the entire test was satisfactory approximating that of previous FT4A testing.

Analysis of the Influence of Geometric Structure on the Rotationally Induced Ingress

2017 ◽  
Author(s):  
Liu Zhenxia ◽  
Ma Jun ◽  
Hu Jianping ◽  
Zhang Lifen
Keyword(s):  
Fluid Dynamics ◽  
Flow Rate ◽  
Geometric Structure ◽  
3D Model ◽  
Turbine Blades ◽  
Fluid Flows ◽  
Not Given ◽  
Radial Gradient ◽  
Velocity Triangle ◽  
Cooling Air

Rotating air inside the wheel-space creates a radial gradient of pressure which drives the gas ingress through the rim seal. This kind of reason for the gas ingestion is called rotationally induced ingress (RI). The minimum sealing flow rate was proportional to the seal-clearance. The geometric structure, including the position of the seal-clearance, is also important to predict the minimum sealing flow rate for RI ingestion. This paper gets the sealing efficiency and the flow results of different geometric structure through the method of 3D steady compressible CFD (Computational Fluid Dynamics). Because the analysis of the influence of geometry is given under the condition of RI ingestion, a 3D model without turbine blades has been chosen. Some experiments initially revealed that the different seal-clearance positions have different sealing efficiency. However, what position would have best sealing efficiency was not given. If the position of seal-clearance is selected in the rotor disc or the static disc, the effect of the “pump” of the rotor disc is more obvious, which makes the gas ingestion serious. When the position of seal-clearance is near the rotor disc, the gas is fully mixed with the cooling air after the ingestion and then flows to the side of the static disc. Therefore, the sealing efficiency of the structure, whose seal-clearance position is near the rotor disc, will be higher than that, whose seal-clearance position is close to the static disc. When the fluid flows to the static disc, the velocity triangle shows that a barrier will be created between the cavity and mainstream in a particular seal-clearance position, which makes the efficiency higher than other positions.

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