Numerical Modelling of High Pressure Gas Face Seals

2005 ◽  
Vol 128 (2) ◽  
pp. 396-405 ◽  
Author(s):  
Sébastien Thomas ◽  
Noël Brunetière ◽  
Bernard Tournerie
Keyword(s):  
High Pressure ◽  
Thermal Effects ◽  
Operating Conditions ◽  
Compressible Fluids ◽  
Face Seal ◽  
Choked Flow ◽  
Exit Boundary ◽  
Face Seals ◽  
Real Behavior ◽  
Gas Face Seal

An axisymetric numerical model of face seals operating with compressible fluids at high pressure is presented. Inertia terms are included using an averaged method and thermal effects are considered. The real behavior of gases at high pressure is taken into account. An original exit boundary condition is used to deal with choked flow. The model is validated by comparison with experimental data and analytical solutions. Finally, the influence of the operating conditions on the performance of a high-pressure gas face seal is analyzed. It is shown that when the flow is choked, the mass flow rate is reduced and the behavior of the seal becomes unstable.

Numerical Modelling of High Pressure Gas Face Seals

2005 ◽  
Author(s):  
Se´bastien Thomas ◽  
Noe¨l Brunetie`re ◽  
Bernard Tournerie
Keyword(s):  
High Pressure ◽  
Thermal Effects ◽  
Operating Conditions ◽  
Compressible Fluids ◽  
Face Seal ◽  
Choked Flow ◽  
Exit Boundary ◽  
Face Seals ◽  
Gas Face Seal ◽  
Comparison With Experimental Data

A numerical model of face seals operating with compressible fluids at high pressure is presented. Inertia terms are included using an averaged method and thermal effects are considered. The real behaviour of gases at high pressure is taken into account. An original exit boundary condition is used to deal with choked flow. The model is validated by comparison with experimental data and analytical solutions. Finally, the influence of the operating conditions on the performance of a high-pressure gas face seal is analysed.

Thermoelastohydrodynamic Behavior of Mechanical Gas Face Seals Operating at High Pressure

2007 ◽  
Vol 129 (4) ◽  
pp. 841-850 ◽  
Author(s):  
Sébastien Thomas ◽  
Noël Brunetière ◽  
Bernard Tournerie
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Numerical Modeling ◽  
Face Seal ◽  
Inertia Effects ◽  
Real Gas ◽  
Choked Flow ◽  
Face Seals ◽  
Mechanical Face Seal ◽  
Gas Expansion

A numerical modeling of thermoelastohydrodynamic mechanical face seal behavior is presented. The model is an axisymmetric one and it is confined to high pressure compressible flow. It takes into account the behavior of a real gas and includes thermal and inertia effects, as well as a choked flow condition. In addition, heat transfer between the fluid film and the seal faces is computed, as are the elastic and thermal distortions of the rings. In the first part of this paper, the influence of the coning angle on mechanical face seal characteristics is studied. In the second part, the influence of the solid distortions is analyzed. It is shown that face distortions strongly modify both the gap geometry and the mechanical face seal’s performance. The mechanical distortions lead to a converging gap, while the gas expansion, by cooling the fluid, creates a diverging gap.

Numerical Analysis of Dry Gas Face Seals With Spiral Groove and Inner Annular Groove

2008 ◽  
Author(s):  
Xu-Dong Peng ◽  
Li-Li Tan ◽  
Ji-Yun Li ◽  
Song-En Sheng ◽  
Shao-Xian Bai
Keyword(s):  
Reynolds Equation ◽  
Geometric Parameters ◽  
Axial Stiffness ◽  
Face Seal ◽  
Optimization Principle ◽  
Face Seals ◽  
The Face ◽  
Gas Face Seal ◽  
Film Stiffness ◽  
Spiral Grooves

A two-dimensional Reynolds equation was established for isothermal compressible gas between the two faces of a dry gas face seal with both spiral grooves and an inner annular groove onto the hard face. The opening force, the leakage rate, the axial film stiffness and the film stiffness to leakage ratio were calculated by finite element method. The comparisons with the sealing performances of a typical gas face seal only with spiral grooves onto its hard face were made. The effects of the face geometric parameters on the static behavior of such a seal were analyzed. The optimization principle for geometric parameters of a dry gas face seals with spiral grooves and an inner annular groove was presented. The recommended geometric parameters of spiral grooves and circular groove presented by optimization can ensure larger axial stiffness while lower leakage rates.

Hydrodynamic Lubrication and Wear in Wavy Contacting Face Seals

1978 ◽  
Vol 100 (1) ◽  
pp. 81-90 ◽  
Author(s):  
A. O. Lebeck ◽  
J. L. Teale ◽  
R. E. Pierce
Keyword(s):  
Surface Roughness ◽  
Hydrodynamic Lubrication ◽  
Surface Profile ◽  
Operating Conditions ◽  
Face Seal ◽  
Hydrodynamic Load ◽  
Surface Waviness ◽  
Wear Rates ◽  
Elastic Deflection ◽  
Face Seals

A model of face seal lubrication is proposed and developed. Hydrodynamic lubrication for rough surfaces, surface waviness, asperity load support, elastic deflection, and wear are considered in the model. Predictions of the ratio of hydrodynamic load support to asperity load support are made for a face seal sealing a low viscosity liquid where some contact does occur and surface roughness is important. The hydrodynamic lubrication is caused by circumferential surface waviness on the seal faces. Waviness is caused by initial out of flatness or any of the various distortions that occur on seal ring faces in operation. The equilibrium solution to the problem yields one dimensional hydrodynamic and asperity pressure distributions, mean film thickness, elastic deflection, and friction for a given load on the seal faces. The solution is found numerically. It is shown that the fraction of hydrodynamic load support depends on many parameters including the waviness amplitude, number of waves around the seal, face width, ring stiffness, and most importantly, surface roughness. For the particular seal examined the fraction of load support would be small for the amount of waviness expected in this seal. However, if the surface roughness were lower, almost complete lift-off is possible. The results of the analysis show why the initial friction and wear rates in mechanical face seals may vary widely; the fraction of hydrodynamic load support depends on the roughness and waviness which are not necessarily controlled. Finally, it is shown how such initial waviness effects disappear as the surface profile is altered by wear. This may take a long or short time, depending on the initial amount of hydrodynamic load support, but unless complete liftoff is achieved under all operating conditions, the effects of initial waviness will vanish in time for steady state conditions. Practical implications are drawn for selecting some seal parameters to enhance initial hydrodynamic load support without causing significant leakage.

Behavior of Hydrostatic and Hydrodynamic Noncontacting Face Seals

1968 ◽  
Vol 90 (2) ◽  
pp. 510-519 ◽  
Author(s):  
H. S. Cheng ◽  
C. Y. Chow ◽  
D. F. Wilcock
Keyword(s):  
Large Diameter ◽  
Initial Imperfection ◽  
Static Stability ◽  
Compressible Fluids ◽  
Face Seal ◽  
Spiral Groove ◽  
Design Data ◽  
Dynamic Tracking ◽  
Face Seals ◽  
Groove Seal

In this paper, the pressure generation and static stability of face-type seals are discussed and an expression is developed to estimate the effectiveness of hydrodynamic action in these seals. Some design data are presented for the hydrostatic step seal, hydrostatic-orifice compensated seal, hybrid spiral-groove seal, and the shrouded Rayleigh step seal. These data are applicable to large-diameter seals for compressible fluids. The seal ring distortions due to initial imperfection, pressure, and thermal expansion are discussed. Approaches to estimate and to minimize the effects of these distortions are outlined. Finally, the ability of a face seal to track the vibrations of the runner is also discussed and methods required to determine the dynamic tracking for rigid or flexible seals are described.

The Parameters Influencing High-Pressure Mechanical Gas Face Seal Behavior in Static Operation

2009 ◽  
Vol 52 (5) ◽  
pp. 643-654 ◽  
Author(s):  
NOËL BRUNETIERE ◽  
SEBASTIEN THOMAS ◽  
BERNARD TOURNERIE
Keyword(s):  
High Pressure ◽  
Face Seal ◽  
Static Operation ◽  
Gas Face Seal

Experimental Studies on Thermoelastic Effects in Hydrodynamically Lubricated Face Seals

1979 ◽  
Vol 101 (3) ◽  
pp. 275-281 ◽  
Author(s):  
B. N. Banerjee ◽  
R. A. Burton
Keyword(s):  
Thermal Effects ◽  
Thermal Equilibrium ◽  
Axial Load ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Surface Waviness ◽  
Thermal Growth ◽  
Face Seals ◽  
Theoretical Predictions ◽  
Thermoelastic Effects

Experiments are reported where face-seat specimens were operated hydrodynamically at conditions close to thermal equilibrium. Changes in surface waviness and mean film thickness were monitored, and compared with theoretical predictions of thermal growth of waviness. Discrepancies were attributed to imperfect response of the gimbals to axial run-out. This run-out was increased by thermal effects at high sliding speeds and led to interactions which influenced the growth of two-lobed waves on the contact face. Operation proved stable, as predicted, under the carefully controlled operating conditions of fixed axial load and self aligning contact.

Low-Leakage Shaft End Seals for Utility-Scale Supercritical CO2 Turboexpanders

2016 ◽  
Author(s):  
Rahul A. Bidkar ◽  
Edip Sevincer ◽  
Jifeng Wang ◽  
Azam M. Thatte ◽  
Andrew Mann ◽  
...  
Keyword(s):  
Large Diameter ◽  
Operating Conditions ◽  
Face Seal ◽  
Cfd Model ◽  
Efficiency Loss ◽  
Power Cycles ◽  
Low Leakage ◽  
Face Seals ◽  
Utility Scale ◽  
Cycle Efficiency

Supercritical carbon dioxide (sCO2) power cycles could be a more efficient alternative to steam Rankine cycles for power generation from coal. In this paper, the end seal layout for a nominally 500 MWe sCO2 turbine is presented and the shaft end sealing requirements for such utility-scale sCO2 turbines are discussed. Shaft end leakage from a closed-loop sCO2 cycle and the associated recompression load can result in net cycle efficiency loss of about 0.55% points to 0.65% points for a nominally 500 MWe sCO2 power cycle plant. Low-leakage hydrodynamic face seals are capable of reducing this leakage loss (and net cycle efficiency loss), and are considered a key enabling component technology for achieving 50–52% or greater thermodynamic cycle efficiencies with indirect coal-fired sCO2 power cycles. In this paper, a hydrodynamic face seal concept is presented for end seals on utility-scale sCO2 turbines. A 3D computational fluid dynamics (CFD) model with real gas CO2 properties is developed for studying the physics of the thin fluid film separating the seal stationary ring and the rotor. The results of the 3D CFD model are also compared with the predictions of a Reynolds-equation-based solver. The 3D CFD model results show large viscous shear and the associated windage heating challenge in sCO2 face seals. Following the CFD model, an axisymmetric finite-element analysis (FEA) model is developed for parametric optimization of the face seal cross-section with the goal of minimizing the coning of the stationary ring. A preliminary thermal analysis of the seal is also presented. The fluid, structural and thermal results show that large-diameter (about 24 inch) face seals with small coning or out-of-plane deformations (of the order of 0.0005 inch) are possible. The fluid, structural and thermal results are used to highlight the design challenges in developing large-diameter and high-differential-pressure face seals for the operating conditions of utility-scale sCO2 turbines.

scholarly journals Dynamic Response to Rotating-Seat Runout in Noncontacting Face Seals

1981 ◽  
Vol 103 (4) ◽  
pp. 587-592 ◽  
Author(s):  
I. Etsion
Keyword(s):  
Dynamic Response ◽  
Dynamic Characteristics ◽  
Operating Conditions ◽  
Face Seal ◽  
Small Perturbations ◽  
Good Insight ◽  
Face Seals ◽  
Tracking Ability ◽  
Mechanical Face Seal ◽  
Insight Into

The dynamic response of a flexibly-mounted ring to runout of the rotating seat in mechanical face seal is analyzed assuming small perturbations. It is found that tracking ability of the stator depends only on its dynamic characteristics and operating conditions and is not affected by the amount of runout. Three different modes of dynamic response are shown and the condition for parallel tracking is presented. The present analysis is limited to flat-faced seals with no secondary seal damping. Nevertheless it provides a good insight into the dynamic behavior of noncontacting face seals.

Thermal Effects in Face Seals

1969 ◽  
Vol 91 (3) ◽  
pp. 434-437 ◽  
Author(s):  
H. J. Sneck
Keyword(s):  
Temperature Distribution ◽  
Turbulent Flow ◽  
Incompressible Fluid ◽  
Thermal Effects ◽  
Face Seal ◽  
Temperature Level ◽  
Face Seals ◽  
Laminar And Turbulent Flow ◽  
Parallel Surfaces

The laminar and turbulent flow of an incompressible fluid between the rotating parallel surfaces of a face seal is investigated analytically to determine the influence of conduction, convection, and dissipation on the temperature distribution. A method of estimating the general temperature level within the seal is suggested.

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