The Effects of Geometry and Inertia on Face Seal Performance—Laminar Flow

1968 ◽  
Vol 90 (2) ◽  
pp. 333-341 ◽  
Author(s):  
H. J. Sneck
Keyword(s):  
Laminar Flow ◽  
Centrifugal Force ◽  
Good Evidence ◽  
Lubrication Theory ◽  
Inertial Effect ◽  
Leakage Flow ◽  
Inertial Effects ◽  
Face Seal ◽  
Geometric Deviations ◽  
The Ideal

The “short bearing” equation of lubrication theory, modified to include inertial effects, is used to study the influence of geometric deviations from the ideal. It is found that the centrifugal force could be responsible for hydrodynamic features of the leakage flow which are theoretically unexplainable in the absence of this inertial effect. There is good evidence that the theory and the results are applicable over the entire laminar range of operation, provided the nominal clearance is small compared to the nominal radius.

The Effects of Geometry and Inertia on Face Seal Performance—Turbulent Flow

1968 ◽  
Vol 90 (2) ◽  
pp. 342-350 ◽  
Author(s):  
H. J. Sneck
Keyword(s):  
Laminar Flow ◽  
Turbulent Flow ◽  
Velocity Distribution ◽  
Power Law ◽  
Apparent Viscosity ◽  
Lubrication Theory ◽  
Inertial Effects ◽  
Face Seal ◽  
Geometric Deviations ◽  
The Ideal

The “short bearing” equation of lubrication theory, modified to include the inertial effects, is used to study the influence of geometric deviations from the ideal. The turbulent nature of the flow is described by an isotropic apparent viscosity and a power-law velocity distribution. It is found that geometric deviations from the ideal are less influential than in laminar flow.

Interaction of Shroud Leakage Flow and Main Flow in a Three-Stage LP Turbine

2003 ◽  
Vol 127 (4) ◽  
pp. 649-658 ◽  
Author(s):  
Jochen Gier ◽  
Bertram Stubert ◽  
Bernard Brouillet ◽  
Laurent de Vito
Keyword(s):  
Main Flow ◽  
Secondary Flows ◽  
Test Facility ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Jet Engines ◽  
Flow Interactions ◽  
Lp Turbine ◽  
The Impact ◽  
The Ideal

Endwall losses significantly contribute to the overall losses in modern turbomachinery, especially when aerodynamic airfoil load and pressure ratios are increased. In turbines with shrouded airfoils a large portion of these losses are generated by the leakage flow across the shroud clearance. Generally the related losses can be grouped into losses of the leakage flow itself and losses caused by the interaction with the main flow in subsequent airfoil rows. In order to reduce the impact of the leakage flow and shroud design related losses a thorough understanding of the leakage losses and especially of the losses connected to enhancing secondary flows and other main flow interactions has to be understood. Therefore, a three stage LP turbine typical for jet engines is being investigated. For the three-stage test turbine 3D Navier-Stokes computations are performed simulating the turbine including the entire shroud cavity geometry in comparison with computations in the ideal flow path. Numerical results compare favorably against measurements carried out at the high altitude test facility at Stuttgart University. The differences of the simulations with and without shroud cavities are analyzed for several points of operation and a very detailed quantitative loss breakdown is presented.

Mistuning Modeling and its Validation for Small Turbine Wheels

2013 ◽  
Author(s):  
David Hemberger ◽  
Dietmar Filsinger ◽  
Hans-Jörg Bauer
Keyword(s):  
Amplification Factor ◽  
Numerical Models ◽  
Lower Sensitivity ◽  
Fe Model ◽  
Mode Localization ◽  
Geometric Deviations ◽  
Probabilistic Study ◽  
Calculated Amplitude ◽  
Amplitude Amplification ◽  
The Ideal

The production of bladed structures, e.g. turbine and compressor wheels, is a subject of statistical scatter. The blades are designed to be identical but differ due to small manufacturing tolerances. This so called mistuning can lead to increased vibration amplitudes compared to the ideal tuned case. The object of this study is to create and validate numerical models to evaluate such mistuning effects of turbine wheels for automotive turbocharger applications. As a basis for the numerical analysis vibration measurements under stand-still conditions were carried out by using a laser surface velocimeter (LSV). The scope of this investigation was to identify the mistuning properties of the turbine wheels namely the frequency deviation from the ideal, cyclic symmetrical tuned system. Experimental modal analyses as well as blade by blade measurements were performed. Moreover 3D scanning techniques were employed to determine geometric deviations. Numerical FE models and a simplified multi degree of freedom model (EBM) were created to reproduce the measured mistuning effects. The prediction of mode localization and the calculated amplitude amplification were evaluated. The best results were obtained with a FE model that employs individual sectorial stiffnesses. The results also indicate that the major contribution to mistuning is made by material inhomogeneities and not by geometric deviations from ideal dimensions. With the adjusted FE model a probabilistic study has been performed to investigate the influence of the mistuning on the amplitude amplification factor. It has been found that at a certain level of mistuning the amplification factor remains constant or slightly decreases. By introducing intentional mistuning a lower sensitivity as well as a decrease of the amplitude amplification could be achieved.

Influence of leakage flow variation on delivery pressure ripple in a vane pump

2013 ◽  
Vol 228 (2) ◽  
pp. 342-357 ◽  
Author(s):  
Yoshiharu Inaguma ◽  
Keiichi Nakamura
Keyword(s):  
Operating Conditions ◽  
Design Stage ◽  
Leakage Flow ◽  
Vane Pump ◽  
Flow Variation ◽  
Ideal Flow ◽  
Chamber Volume ◽  
Delivery Pressure ◽  
Pressure Ripple ◽  
The Ideal

This article describes the theoretical analysis and experimental verification of the influence of variations of leakage flow as well as ideal flow on delivery pressure ripple in a balanced vane pump. The analytical model for simulating the delivery pressure ripple of the pump is simplified. It is composed of only the ripple of the ideal flow based on the theoretical pump displacement determined from geometrical pump dimensions, the leakage flow variation dependent on the pump dimensions including clearances and pump-operating conditions, an oil chamber volume in the pump and the impedance of a hydraulic circuit with a throttle valve set close to a pump outlet. The purpose of this study is to predict the pump delivery pressure ripple at the design stage of the vane pump. This article reveals that the delivery pressure ripple can be theoretically predicted through the calculations of the leakage flow as well as the ideal flow. The waveform of the delivery pressure ripple calculated agrees well with the measured one. The leakage flow variation significantly affects the delivery pressure ripple and it can be also calculated accurately from the pump dimensions including the clearances and pump-operating conditions. In addition, the components of the leakage flow are clarified and their effects on the delivery pressure ripple are investigated.

Analytical Investigation of the Spiral Groove Face Seal

1973 ◽  
Vol 95 (4) ◽  
pp. 499-510 ◽  
Author(s):  
H. J. Sneck ◽  
J. F. McGovern
Keyword(s):  
Mathematical Model ◽  
Parametric Design ◽  
Analytical Investigation ◽  
Performance Characteristics ◽  
Comprehensive Model ◽  
Inertial Effects ◽  
Face Seal ◽  
Spiral Groove ◽  
Design Studies

An analytical investigation of both a simplified and a comprehensive mathematical model of a spiral groove face seal, using the “narrow seal” approximation. The sealing fluid is assumed to be incompressible and Newtonian. The inertial effects associated with seal curvature are incorporated in the comprehensive model. The results of the analysis are programmed for computer computation in order to facilitate their application in parametric design studies. Performance characteristics are calculated for some particular seal designs.

scholarly journals Numerical Flow Analysis in a Rotating Square Duct and a Rotating Curved-Duct

2000 ◽  
Vol 6 (1) ◽  
pp. 1-9
Author(s):  
Je Hyun Baekt ◽  
Chang Hwan Ko
Keyword(s):  
Laminar Flow ◽  
Viscous Fluid ◽  
Secondary Flow ◽  
Centrifugal Force ◽  
Coriolis Force ◽  
Axial Velocity ◽  
Numerical Study ◽  
Axial Direction ◽  
Square Duct ◽  
Rotation Rates

A numerical study is conducted on the fully-developed laminar flow of an incompressible viscous fluid in a square duct rotating about a perpendicular axis to the axial direction of the duct. At the straight duct, the rotation produces vortices due to the Coriolis force. Generally two vortex cells are formed and the axial velocity distribution is distorted by the effect of this Coriolis force. When a convective force is weak, two counter-rotating vortices are shown with a quasi-parabolic axial velocity profile for weak rotation rates. As the rotation rate increases, the axial velocity on the vertical centreline of the duct begins to flatten and the location of vorticity center is moved near to wall by the effect of the Coriolis force. When the convective inertia force is strong, a double-vortex secondary flow appears in the transverse planes of the duct for weak rotation rates but as the speed of rotation increases the secondary flow is shown to split into an asymmetric configuration of four counter-rotating vortices. If the rotation rates are increased further, the secondary flow restabilizes to a slightly asymmetric double-vortex configuration. Also, a numerical study is conducted on the laminar flow of an incompressible viscous fluid in a90°-bend square duct that rotates about axis parallel to the axial direction of the inlet. At a90°-bend square duct, the feature of flow by the effect of a Coriolis force and a centrifugal force, namely a secondary flow by the centrifugal force in the curved region and the Coriolis force in the downstream region, is shown since the centrifugal force in curved region and the Coriolis force in downstream region are dominant respectively.

The Eccentric Face Seal with A Tangentially Varying Film Thickness

1969 ◽  
Vol 91 (4) ◽  
pp. 748-755 ◽  
Author(s):  
H. J. Sneck
Keyword(s):  
Film Thickness ◽  
Phase Angle ◽  
Leakage Flow ◽  
Face Seal ◽  
Surface Waviness ◽  
Total Leakage

It is shown analytically that face seal eccentricity combined with surface waviness can contribute an inward or outward leakage component to the total leakage flow depending on the phase angle between the eccentricity and the waviness.

Inertial Considerations in Parallel Circular Squeeze Film Bearings

1970 ◽  
Vol 92 (4) ◽  
pp. 588-592 ◽  
Author(s):  
J. A. Tichy ◽  
W. O. Winer
Keyword(s):  
Newtonian Fluid ◽  
Film Flow ◽  
Momentum Equation ◽  
Lubrication Theory ◽  
Squeeze Film ◽  
Experimental Measurements ◽  
Inertial Effects ◽  
Regular Perturbation ◽  
Parallel Surfaces ◽  
Good Agreement

A second order regular perturbation solution for squeeze film flow of a Newtonian fluid between circular parallel surfaces is presented. All the inertial terms are included in the momentum equation. Experimental measurements of pressure in a squeeze film at high squeeze rates are shown to be in good agreement with the solution. The solution is particularly useful in assessing the extent to which fluid inertial effects would cause the classical lubrication theory to be in error for any particular squeeze film. The inertial effects are shown to be functions of two readily determined dimensionless parameters, the squeeze Reynold’s number Res and the squeeze acceleration number A.

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