Rub-Groove Width and Depth Effects on Flow Predictions for Straight-Through Labyrinth Seals

2004 ◽  
Vol 126 (4) ◽  
pp. 781-787 ◽  
Author(s):  
David L. Rhode ◽  
Richard G. Adams
Keyword(s):  
Turbulence Model ◽  
Groove Depth ◽  
Groove Width ◽  
Navier Stokes ◽  
Radial Clearance ◽  
Two Dimensional ◽  
Labyrinth Seals ◽  
Dramatic Effect ◽  
Finite Volume Discretization ◽  
Depth Effects

A fully compressible, two-dimensional axisymmetric, turbulent Navier-Stokes code using the finite-volume discretization approach was utilized to obtain an enhanced understanding of the effects of rub-grooves in straight-through, abradable labyrinth seals. The high-Re form of the k-ε turbulence model was used. The code was first validated against measurements of straight-through honeycomb labyrinths, and accurate results were obtained. It was found that in most of the cases considered (tooth tip outside of its rub groove), the presence of rub-grooves increases the leakage, except for the case of the large pre-rub clearance and narrow rub-groove width. The presence of the large- or the intermediate-width rub-grooves allows the rub-groove depth to exert a fairly large effect on the leakage, especially for the smallest pre-rub radial clearance. Further, the presence of a narrow rub-groove with the smallest pre-rub radial clearance gives a dramatic effect on the streamwise (i.e., cavity-to-cavity) variation in overall flow patten.

scholarly journals Numerical Investigation on Flow Characteristics and Aerodynamic Performance of a 1.5-Stage SCO2 Axial-Inflow Turbine with Labyrinth Seals

2020 ◽  
Vol 10 (1) ◽  
pp. 373 ◽  
Author(s):  
Qiuwan Du ◽  
Di Zhang
Keyword(s):  
Pressure Ratio ◽  
Flow Characteristics ◽  
Groove Depth ◽  
Aerodynamic Performance ◽  
Rotor Blades ◽  
Groove Width ◽  
Cavity Surface ◽  
Labyrinth Seals ◽  
Blade Tip ◽  
Peak Value

The leakage problem of supercritical carbon dioxide (SCO2) axial-inflow turbine brings great challenges to the efficiency and security of the power system. Labyrinth seals are usually utilized to improve the leakage characteristics of the blade tip. In this paper, a 1.5-stage SCO2 axial-inflow turbine is established and labyrinth seals are arranged on the top of the first stage stator and rotor blades. The effects of seal clearance, groove on seal cavity surface and circle groove shape on flow characteristics and aerodynamic performance under different pressure ratio are investigated. Increasing seal clearance can significantly weaken the turbine performance. Arranging rectangle, circle and V-shaped grooves on the seal cavity surface near the outlet of the seal gap can enhance the energy dissipation, reduce the relative leakage and improve the power and efficiency. Increasing the groove width can improve the aerodynamic performance while the effect of the groove depth is weak. The configuration where the circle groove width is 50% of the pitch of seal tooth achieves the best performance with the relative leakage of stator1 and rotor, power and efficiency of 6.04 × 10−3, 8.09 × 10−3, 3.467 MW and 86.86% respectively. With an increase in pressure ratio, the relative leakage increases firstly and then remains almost constant. The power increases while the efficiency increases firstly and then decreases, reaching the peak value under the design condition.

Incompressible Navier-Stokes Computation of the NREL Airfoils Using a Symmetric Total Variational Diminishing Scheme

1994 ◽  
Vol 116 (4) ◽  
pp. 174-182 ◽  
Author(s):  
S. L. Yang ◽  
Y. L. Chang ◽  
O. Arici
Keyword(s):  
Turbulence Model ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Wind Tunnel Test ◽  
Factorization Method ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Approximate Factorization ◽  
Two Dimensional Flow ◽  
Good Agreement

The purpose of this paper is to present a numerical study of flow fields for the NREL S805 and S809 airfoils using a spatially second-order symmetric total variational diminishing scheme. The steady two-dimensional flow is modeled as turbulent, viscous, and incompressible and is formulated in the pseudo-compressible form. The turbulent flow is closed by the Baldwin-Lomax algebraic turbulence model. Numerical solutions are obtained by the implicit approximate-factorization method. The accuracy of the numerical results is compared with the Delft two-dimensional wind tunnel test data. For comparison, the Eppler code results are also included. Numerical solutions of pressure and lift coefficients show good agreement with the experimental data, but not the drag coefficients. To properly simulate the post-stall flow field, a better turbulence model should be used.

Study on a Type of Low-Leakage Brush Seal Porous Media Model

2013 ◽  
Vol 312 ◽  
pp. 345-349 ◽  
Author(s):  
Shou Qing Huang ◽  
Shuang Fu Suo ◽  
Kai Bing Du ◽  
Yong Jian Li ◽  
Yu Ming Wang
Keyword(s):  
Ring Structure ◽  
Navier Stokes ◽  
Radial Clearance ◽  
Two Dimensional ◽  
Low Leakage ◽  
Brush Seal ◽  
Porous Media Model ◽  
Retaining Ring ◽  
Anisotropic Porous Medium ◽  
Porous Medium Model

Computation Fluid Dynamics (CFD) has been employed to calculate the pressure, flow distributions and leakage of brush seal by using Reynolds-Averaged-Navier-Stokes (RANS) method and two-dimensional axisymmetric anisotropic porous medium model. The leakage in brush seal with radial clearance has a marked increase compared with contact brush seal. The leakages of brush seal with different radial clearances have been investigated comparing contact brush seal. A type ofretaining ring structure has been employedto reduce the leakage on radial clearance condition. Also the disturbance effect of retaining ring on bristle pack has been studied.

Clocking Effects in a 1.5-Stage Axial Turbine: Boundary Layer Behaviour at Midspan

2004 ◽  
Author(s):  
Sven Ko¨nig ◽  
Axel Heidecke ◽  
Bernd Stoffel ◽  
Andreas Fiala ◽  
Karl Engel
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Pressure Distribution ◽  
Static Pressure ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Discretization Scheme ◽  
Low Pressure Turbine ◽  
Finite Volume Discretization ◽  
Hot Film

This paper presents an experimental and numerical investigation on the influence of clocking on the boundary layer behaviour of the second stator in a 1.5-stage axial low pressure turbine. Surface mounted hot-film sensors were used to measure the quasi shear stress on the second stator and static pressure tappings to obtain the pressure distribution. All experiments were carried out at midspan for different clocking positions. The supporting numerical calculations were conducted with a two-dimensional Navier-Stokes solver using a finite volume discretization scheme and the v′2f turbulence model.

Computed Effect of Rub-Groove Size on Stepped Labyrinth Seal Performance

2000 ◽  
Author(s):  
David L. Rhode ◽  
Richard G. Adams
Keyword(s):  
Friction Coefficient ◽  
Stokes Equations ◽  
Numerical Study ◽  
Groove Depth ◽  
Radial Clearance ◽  
Intermediate Step ◽  
Labyrinth Seals ◽  
Wall Functions ◽  
Small Clearance ◽  
Wide Groove

A numerical study was undertaken to explore the effects of the size of wear-in rub grooves that are typically cut into the abradable land of stepped labyrinth seals. The elliptic form of the 2-D axisymmetric Navier-Stokes equations for compressible turbulent flow were solved. The relationships among the friction coefficient, the leakage Reynolds number, the groove depth and width and the pre-rub radial clearance were examined. It was found that the standard k-ε turbulence model and wall functions are effective for computing the friction coefficient and leakage for labyrinth seals with honeycomb land surfaces, both with and without the presence of rub grooves. The so-called rub grooves are the result of labyrinth teeth cutting wear grooves into the abradable surface of the land (stationary housing of the seal). Furthermore, it was found that the case of a small pre-rub tooth radial clearance, a wide rub groove and an intermediate step height is the most sensitive to the presence of a rub groove, with a leakage increase over the no-groove case of about 100 percent and 194 percent for the shallow and deep grooves, respectively. It was also found, for example, that the leakage varied with pre-rub clearance and groove width, in order from lowest to highest leakage, as: (a) small clearance and narrow groove, (b) small clearance and wide groove, (c) large clearance and narrow groove and (d) large clearance and wide groove.

Numerical Investigations for Leakage and Windage Heating in Straight-Through Labyrinth Seals

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Kali Charan Nayak ◽  
Pradip Dutta
Keyword(s):  
Cell Size ◽  
Turbulence Model ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Labyrinth Seal ◽  
Radial Clearance ◽  
Labyrinth Seals ◽  
Turbine Engine ◽  
Honeycomb Cell

The ability to quantify leakage flow and windage heating for labyrinth seals with honeycomb lands is critical in understanding gas turbine engine system performance and predicting its component life. Variety of labyrinth seal configurations (number of teeth, stepped or straight, honeycomb cell size) are in use in gas turbines, and for each configuration, there are many geometric factors that can impact a seal's leakage and windage characteristics. This paper describes the development of a numerical methodology aimed at studying the effect of honeycomb lands on leakage and windage heating. Specifically, a three-dimensional computational fluid dynamics (CFD) model is developed utilizing commercial finite volume-based software incorporating the renormalization group (RNG) k-ε turbulence model with modified Schmidt number. The modified turbulence model is benchmarked and fine-tuned based on several experiments. Using this model, a broad parametric study is conducted by varying honeycomb cell size, pressure ratio (PR), and radial clearance for a four-tooth straight-through labyrinth seal. The results show good agreement with available experimental data. They further indicate that larger honeycomb cells predict higher seal leakage and windage heating at tighter clearances compared to smaller honeycomb cells and smooth lands. However, at open seal clearances larger honeycomb cells have lower leakage compared to smaller honeycomb cells.

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