scholarly journals Experimental and numerical study on the performance of the smooth-land labyrinth seal

2016 ◽  
Vol 760 ◽  
pp. 012033 ◽  
Author(s):  
A Szymanski ◽  
S Dykas ◽  
W Wróblewski ◽  
M Majkut ◽  
M Strozik
Keyword(s):  
Numerical Study ◽  
Labyrinth Seal

Sharper Labyrinth Seal Edges to Allow Greater Clearance Without Increased Leakage

1995 ◽  
Author(s):  
David L. Rhode ◽  
M. J. Guidry
Keyword(s):  
Numerical Study ◽  
Energy Generation ◽  
Labyrinth Seal ◽  
Leakage Rate ◽  
Turbulence Energy ◽  
Resistance Increase ◽  
Leakage Resistance ◽  
Edge Sharpness ◽  
Damage Susceptibility

Abstract A numerical study was undertaken to examine the effects of utilizing sharper edges for increasing the leakage resistance of advanced labyrinth seal configurations. Such an increase allows the designer to enlarge the extremely small knife clearance, providing a seal with less damage susceptibility at the same leakage rate. The maximum possible leakage resistance increase from changing three cavity edges to perfectly sharp ones was estimated from the present computations. In addition, previous measurements of the edge sharpness effect on the leakage through orifices are appropriately utilized to obtain a rough estimate of the resistance increase for generic seals. The latter allows consideration of a broader range of application. Further, turbulence energy generation contours reveal that only one particular cavity edge needs to be sharpened in order to obtain a significantly increased leakage resistance.

scholarly journals Numerical Simulation of Secondary Flow in Gas Turbine Disc Cavities, Including Conjugate Heat Transfer

1996 ◽  
Author(s):  
Y.-H. Ho ◽  
M. M. Athavale ◽  
J. M. Forry ◽  
R. C. Hendricks ◽  
B. M. Steinetz
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Conjugate Heat Transfer ◽  
Gas Flow ◽  
Numerical Study ◽  
Labyrinth Seal ◽  
Temperature Fields ◽  
Heat Transfer Analysis ◽  
Flow Rates ◽  
Turbine Disc

A numerical study of the flow and heat transfer in secondary flow elements of the entire inner portion of the turbine section of the Allison T-56/501D engine is presented. The flow simulation included the interstage cavities, rim seals and associated main path flows, while the energy equation also included the solid parts of the turbine disc, rotor supports, and stator supports. Solutions of the energy equations in these problems usually face the difficulty in specifications of wall thermal boundary conditions. By solving the entire turbine section this difficulty is thus removed, and realistic thermal conditions are realized on all internal walls. The simulation was performed using SCISEAL, an advanced 2D/3D CFD code for predictions of fluid flows and forces in turbomachinery seals and secondary flow elements. The mass flow rates and gas temperatures at various seal locations were compared with the design data from Allison. Computed gas flow rates and temperatures in the rim and labyrinth seal show a fair 10 good comparison with the design calculations. The conjugate heat transfer analysis indicates temperature gradients in the stationary intercavity walls, as well as the rotating turbine discs. The thermal strains in the stationary wall may lead to altered interstage labyrinth seal clearances and affect the disc cavity flows. The temperature, fields in the turbine discs also may lead to distortions that can alter the rim seal clearances. Such details of the flow and temperature fields are important in designs of the turbine sections to account for possible thermal distortions and their effects on the performance. The simulation shows that the present day CFD codes can provide the means to understand the complex flow field and thereby aid the design process.

Numerical Investigation of an Improved Gas and Steam Turbine Seal

1996 ◽  
Vol 210 (6) ◽  
pp. 477-479 ◽  
Author(s):  
M H Gordon ◽  
U M Kelkar ◽  
M C Johnson
Keyword(s):  
High Temperature ◽  
Numerical Investigation ◽  
High Speed ◽  
Numerical Study ◽  
Dynamic Pressure ◽  
Labyrinth Seal ◽  
Optimal Shape ◽  
Steam Turbines ◽  
Brush Seal ◽  
Sealing Mechanism

A numerical study has been conducted to assess the viability of a new sealing mechanism for gas and steam turbines. This new static-to-rotating sealing mechanism is mounted on flexible legs which permit radial movement and is designed to take advantage of the hydro-dynamic pressure forces, which result from fluid leaking around the seal, to maintain an ideally small and constant clearance. Relatively simple seal geometries have been numerically tested to find an optimal shape. These results indicate that a substantial sealing improvement (between two and four times less leakage) relative to a labyrinth seal is possible. Although these results show that a brush seal is more effective than the present seal, the present seal is designed to operate in high-speed and high-temperature environments in which the brush seal would degrade.

A Numerical Study of Labyrinth Seal Flutter

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
L. di Mare ◽  
M. Imregun ◽  
J. S. Green ◽  
A. I. Sayma
Keyword(s):  
Numerical Study ◽  
Large Diameter ◽  
Labyrinth Seal ◽  
Navier Stokes ◽  
Time Step ◽  
Modal Model ◽  
Flutter Analysis ◽  
Time Histories ◽  
Structural Motion ◽  
Good Agreement

A numerical study of a labyrinth-type turbine seal flutter in a large turbofan engine is described. The flutter analysis was conducted using a coupled fluid-structure interaction code, which was originally developed for turbomachinery blade applications. The flow model is based on an unstructured, implicit Reynolds-averaged Navier–Stokes solver. The solver is coupled to a modal model for the structure obtained from a standard structural finite element code. During the aeroelasticity computations, the aerodynamic grid is moved at each time step to follow the structural motion, which is due to unsteady aerodynamic forces applied onto the structure by the fluid. Such an integrated time-domain approach allows the direct computation of aeroelastic time histories from which the aerodynamic damping, and hence, the flutter stability, can be determined. Two different configurations of a large-diameter aeroengine labyrinth seal were studied. The first configuration is the initial design with four fins, which exhibited flutter instability during testing. The second configuration is a modified design with three fins and a stiffened ring. The steady-state flow was computed for both configurations, and good agreement was reached with available reference data. An aeroelasticity analysis was conducted next for both configurations, and the model was able to predict the observed flutter behavior in both cases. A flutter mechanism is proposed, based on the matching of the structural frequencies to the frequencies of waves traveling in the fluid, in the interfin cavities and in the high- and low-pressure cavities.

scholarly journals Numerical Study of Shaft-Seal Parameters for Various Geometry Configurations and Operation Regimes

2018 ◽  
Vol 180 ◽  
pp. 02100 ◽  
Author(s):  
Petr Straka
Keyword(s):  
Numerical Study ◽  
Pressure Ratio ◽  
Labyrinth Seal ◽  
Geometrical Parameters ◽  
Turbine Stage ◽  
Shaft Seal ◽  
Flow Angle ◽  
Geometric Configurations ◽  
Outlet Flow ◽  
Flow Through

The contribution deals with numerical modelling of flow through the shaft labyrinth seal for various geometric configurations and operating states. The objective is to obtain dependency of the mass flow rate through the seal and the outlet flow angle from the seal on the pressure ratio and the rotation speed for various seal clearances and other geometrical parameters. The results will be used as a background for modification of the test-rig for axial turbine stage.

An Experimental and Numerical Study of Labyrinth Seal Flow

2005 ◽  
Author(s):  
A. D. Vakili ◽  
A. J. Meganathan ◽  
M. Michaud ◽  
S. Radhakrishnan
Keyword(s):  
Numerical Study ◽  
Field Measurements ◽  
Labyrinth Seal ◽  
Labyrinth Seals ◽  
Streamline Curvature ◽  
Seal Design ◽  
Turbine Generators ◽  
Flow Stagnation ◽  
Viscous Losses ◽  
Modeling And Experiments

Leakage flow in 2-D constant rotor diameter stepped labyrinth seals is investigated by means of pressure and velocity field measurements and numerical simulation of 2-D and axisymmetric models. The basis of investigation is a generic stepped labyrinth seal currently used in industry in steam turbine generators. The performance of the baseline seal design was compared with new seal designs with specific features changed in order to examine their influence on leakage characteristics through such seals. Numerical modeling and experiments were performed over a range of seal pressure ratios from 1 to 10. A number of configurations were evaluated both experimentally and numerically. This paper discusses flow details associated with only one configuration as compared with the baseline. Results have been helpful in the understanding of seal flow leakage and total pressure loss mechanisms. Mechanisms of leakage reduction in labyrinth seals included turbulence induced viscous losses, chamber vortex generation, flow stagnation losses, and increased flow streamline curvature. Numerical results provided insight into the flow field details and were helpful in facilitating basic physical understandings used for improved seal designs.

Analysis of Gas Turbine Rim Cavity Ingestion With Axial Purge Flow Injection

2019 ◽  
Author(s):  
Christopher W. Robak ◽  
Amir Faghri ◽  
Karen A. Thole
Keyword(s):  
Experimental Data ◽  
Complex Geometry ◽  
Numerical Study ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Purge Flow ◽  
Inner Diameter ◽  
Urans Cfd

Abstract Turbine rim cavities require an adequate supply of cooling purge flow to prevent hot gas ingestion from overheating metal components beneath the gas path airfoils. Purge flow is typically introduced into rim cavities through a labyrinth seal at the inner diameter of the cavity, or through conduits in the metal walls of the rim cavity. This numerical study will focus on purge flow introduced through axial holes in the stationary side of a turbine realistic rim cavity. Three dimensional Unsteady Reynolds-average Navier-Stokes (URANS) CFD modeling is utilized to model of cavity sealing effectiveness as a function of axial purge flow rate. CFD modeling is compared with experimental data from the test turbine in the Steady Thermal Aero Research Turbine (START). Results show good agreement with experimental data, especially at lower purge flow rates. Analytical depictions of the flow field setup in the rim cavity are provided, explaining trends observed in experimental data. Differences in sealing effectiveness trends between the upper and lower portions of the rim cavity are predicted by CFD modeling, adding insight to ingestion phenomena in turbine realistic rim cavities with complex geometry and flow leakage paths.

Mechanical Growth of Labyrinth Seal

2013 ◽  
Vol 465-466 ◽  
pp. 578-581
Author(s):  
Saurav Das ◽  
Hoong Thiam Toh
Keyword(s):  
Experimental Work ◽  
Rotational Speed ◽  
Qualitative Agreement ◽  
Numerical Study ◽  
Labyrinth Seal ◽  
Radial Deformation

A preliminary numerical study has been conducted to study the effect of rotational speed on centrifugal growth in a six-tooth straight labyrinth seal. The distribution of the radial deformation along the seal axis for the rotational speed ranging from 100 rpm to 1500 rpm is reported in this paper. The radial deformation which decreases the clearance between the rotating and stationary parts of sealing surface is an indication that centrifugal growth occurs. The results of the simulation indicate that centrifugal growth increases as rotational speed increases. This finding is in qualitative agreement with other numerical and experimental work reported in the literature.

Time-Resolved Numerical Study of Axial Gap Effects on Labyrinth-Seal Leakage and Secondary Flow in a LP Turbine

2013 ◽  
Author(s):  
Marc H.-O. Biester ◽  
Florian Wiegmann ◽  
Yavuz Guendogdu ◽  
Joerg R. Seume
Keyword(s):  
Secondary Flow ◽  
Numerical Study ◽  
Flow Direction ◽  
Labyrinth Seal ◽  
Flow Structures ◽  
Leakage Flow ◽  
Labyrinth Seals ◽  
Time Resolved ◽  
Flow Angle ◽  
Blade Row

One of the most promising ways to improve the efficiency of modern turbomachinery is the reduction of secondary flow-structures and associated losses. A widely spread approach is the usage of shrouded airfoils in combination with labyrinth-seals. The disadvantage of this arrangement is a small but inevitable labyrinth-leakage flow that tends to increase the secondary-flow structures. The present work investigates how the axial gap of the blade rows and the corresponding shift of the labyrinth’s inlet and outlet influences leakage related effects on the flow-field and loss-generation. In order to capture the inter-blade and leakage interaction properly, time-resolved RANS computations of a 1 1/2 stage low pressure turbine have been performed. Besides accounting for labyrinth seals, fillets have been modeled. The axial gap is varied from 20% to 80% axial chord length. Clocking-effects induced by the axial gap variation are compensated. The leakage flow nearly retains the flow direction of the flow entering the blade row. In case of the largest axial gap, mixing causes the flow-angle of the leakage to tend towards that of the main-flow, thus reducing the incidence on the downstream blade row. Therefore, the turning of the low-momentum flow is increased compared to a small axial gap. This leads to a higher loading in the affected region and an increased passage vortex can be observed. By comparing the entropy generation of computations with and without labyrinth seals, the regions where leakage-related losses occur are identified and the relevant mechanisms are distinguished.

Leakage and Rotordynamics Numerical Study of Circular Grooved and Rectangular Grooved Labyrinth Seals

2013 ◽  
Author(s):  
Emanuel Marsis ◽  
Gerald Morrison
Keyword(s):  
Cfd Simulation ◽  
Numerical Study ◽  
Low Pressure ◽  
Labyrinth Seal ◽  
Labyrinth Seals ◽  
Cfd Simulations ◽  
Circular Groove ◽  
Groove Design ◽  
Seal Design ◽  
Rectangular Groove

Labyrinth seals are used in many turbomachines to reduce the leakage from high to low pressure zones. In this paper, a new labyrinth seal design with a circular groove is presented. A 2D CFD simulation was used to model the leakage and optimize the tooth thickness of the new design and compare it to the traditional labyrinth seals with a rectangular groove. The rotordynamics coefficients for the new circular groove design as well as the traditional rectangular groove design were computed using 3D CFD simulations. The results show that the new proposed design provides less leakage than the traditional rectangular groove design. Moreover the new design provides more direct damping when compared to the traditional rectangular labyrinth seal.

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