A Model for Squeeze Film Dampers Operating With Air Entrainment and Validation With Experiments

Dı́az, Belén Dı́az; Andrés, Luis San

doi:10.1115/1.1330742

Cited by 57 publications

(31 citation statements)

References 19 publications

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“…Fig. 3 shows that by directly applying equation (13) or (14) the volume of transferred liquid will not be preserved because the double hatched area will be lost. To avoid this situation, a method called "split operator" is commonly used [20], [21], [25], [26].…”

Section: ( )mentioning

confidence: 96%

“…The key point in solving equations (13) or (14) is the evaluation of f i when interfaces are present in the computational cell. The interface crossing a computational cell has an arbitrary slope.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Thus, the model associated to a low reference volume fraction such as, model. The cavitation model used by Singhal in a CFD software[10], uses a comparable approach to deal with vapor cavitation.NUMERICAL MODEL FOR AIR INGESTION WITH THE VOF METHODAs mentioned in the Introduction, Diaz and San Andrés[12],[13] have proposed an approach for air ingestion obtained after some simplifications of the RP equation (i.e. including only surface tension effects).…”

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confidence: 99%

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A Volume of Fluid Method for Air Ingestion in Squeeze Film Dampers

Gehannin

Arghir

Bonneau

2016

Tribology Transactions

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The present work introduces a numerical model for squeeze film dampers (SFD) operating simultaneously with vapor cavitation and air ingestion. The pressure is given by the Reynolds equation. The vapor cavitation model used in this work is based on Rayleigh-Plesset equation and was previously presented. Air ingestion occurring in open end SFD is dealt with by using a volume of fluid CFD method never employed in Lubrication problems up to now. The original volume of fluid (VOF) method proposed by Hirt and Nichols was adapted for capturing and tracking the free boundary between air and liquid in a thin film lubricant. Numerical results are compared with experimental data of Adiletta and Pietra showing the simultaneous influence of vapor cavitation and air ingestion in an open end SFD. These two phenomena have typical pressure values and appear at different locations and with a different extent. The vapor threshold is located on the low-pressure zone and is the lowest pressure value in the SFD, usually close to Downloaded by [University of California, San Diego] at 03:12 31 December 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 absolute zero. The air ingestion is characterised by a zone of almost constant pressure, usuallyclose to the atmospheric pressure (or, more generally, equal to the outer, exit pressure) and located between the minimum and the maximum pressures in the SFD. The numerical model proposed in this paper deals simultaneously with these two effects. A simplified version of the air ingestion model for standard SFD applications is also introduced. Keywordssqueeze film damper, air ingestion, vapor cavitation Downloaded by [University of California, San Diego] at 03:12 31 December 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 3 NOMENCLATURE A Bubble surface [mm²] C Radial clearance [mm] CFS Additional fluid flux [m 3 ] d Offset [mm] D Squeeze diameter [mm] dt Time step [s] dz Axial space step [m] dx Circumferential space step [m] e Eccentricity [m] f Lubricant volume flow rate [m 3 ] F Volume fraction of lubricant H Film thickness [mm] L Squeeze length [mm] N CFL Courant-Friedrichs-Levy Number B O Bearing center [m] J O Journal center [m] p Absolute pressure [Pa] a p Reference pressure [Pa] B p Bubble pressure [Pa] v p Vapor pressure [Pa] Downloaded by [University of California, San Diego] at 03:12 31 December 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 4 q Total transfered volume [m 3 ] R Bubble radius [m] r Orbit radius [mm] a R Reference bubble radius [m] S Lateral surface of the cell [ 2 m ] u Average velocity at the volume faces [m.s -1 ] U Average norm velocity [ 1 . m s -] U 0 1 H x V dy H = ò , Average axial velocity [ 1 . m s -] W 0 1 H z V dy H = ò , Average circumferential velocity [ 1 . m s -] V =Hdxdz, Volume of the cell [m 3 ] ( ) , , x y z V V V V = r Velocity vector [ 1 . m s -] a Volume fraction of vapor phase a a Reference volume fraction of vapor phase k Dilatation viscosity [ 1 . . N s m -] m Lubricant viscosity [Pa.s] air m Air viscosity [Pa.s] GNC m Non-condensable gas viscosity [Pa...

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Section: Accepted Manuscriptmentioning

confidence: 99%

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A Volume of Fluid Method for Air Ingestion in Squeeze Film Dampers

Gehannin

Arghir

Bonneau

2016

Tribology Transactions

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“…The hole feed system affects the damper performance in a direct way, in view of the pressure build up resulting from the interaction between the film land flow and the injection holes. An indirect influence can also show up whenever the feeding capability is not high enough to prevent air entrainment into the film, which leads to operation with a bubbly oil (Diaz and San Andres, 2001). Hence, the hole feed system model must be able to provide good estimates of the pressure at the oil injection holes as well as of the flow into the film.…”

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confidence: 98%

Interaction of Squeeze Film Dampers and Hole Feed Systems and Its Influence on the Dynamics of a Jeffcott Rotor

Rodrigues¹,

Jézéquel²,

Thouverez³

2004

The International Journal of Rotating Machinery

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The oil feeding of a squeeze film damper through holes can be an interesting solution to improve the damper's energy dissipation capability since it increases the journal's effective squeezing surface. While groove feeding has been extensively studied, only a few works have addressed the problem of hole fed dampers. The squeeze film damper model may be able to estimate the pressure at the feed holes as well as the flow into the film. A fundamental issue in the modeling of the hole feed system is the choice of the adequate boundary conditions. Existing published models consider the supply pressure to be constant at a specific section of the hydraulic system. The pressures at the oil injection holes are then obtained via local flow balances taking into account a linear flow resistance across the feed conduits. The model developed in the present work is based on the application of the simplified form of the energy equation commonly used in hydraulics, with approximate pressure drop coefficients. As a boundary condition we impose the power supplied to the pump. The nonlinear hydraulics problem is coupled with the squeeze flow and the Newton-Raphson method is employed to solve the set of nonlinear equations. The influence of the hole feed system on the unbalance response and stability of a Jeffcott rotor is analyzed in regards to the number of feed holes and the power supplied to the pump. The feed system behavior is also studied. technological developments to occur in rotating machinery during the last three decades. When correctly conceived, these dampers can improve rotor stability, attenuate vibration levels, and reduce transmissibility. A significant number of theoretical and experimental works have been published since the 1960s as the interest in the application of this kind of damper grew strong. As far as the oil film pressure distribution is concerned, the majority of the studies have focused on cavitation modeling, fluid inertia effects, non-Newtonian fluid behavior, and operation with bubbly oil. Despite the consensus about the importance of the damper's boundary conditions, namely the feed system and the leakage conditions, a relatively limited number of works addressed these issues. Regarding the feed system, circumferential groove-fed dampers have already been extensively examined by San Andres (1992) and Arauz and San Andres (1994), who evidenced the influence of the interaction between land and groove flows on the SFD performance. However, for hole fed dampers, a configuration which can turn out to be an interesting way to improve damping capability (Wang and Hahn, 1995), only a few models have been proposed. The hole feed system affects the damper performance in a direct way, in view of the pressure build up resulting from the interaction between the film land flow and the injection holes. An indirect influence can also show up whenever the feeding capability is not high enough to prevent air entrain-ment into the film, which leads to operation with a bubbly oil (Diaz and San Andres, 2001). Hence, t...

show abstract

“…An indirect influence can also show up whenever the feeding capability is not high enough to prevent air entrainment into the film, which leads to operation with a bubbly oil (Diaz and San Andres, 2001). Hence, the hole feed system model must be able to provide good estimates of the pressure at the oil injection holes as well as of the flow into the film.…”

mentioning

confidence: 99%

Interaction of Squeeze Film Dampers and Hole Feed Systems and Its Influence on the Dynamics of a Jeffcott Rotor

Rodrigues

Thouverez²,

Jézéquel³

2004

International Journal of Rotating Machinery

View full text Add to dashboard Cite

The oil feeding of a squeeze film damper through holes can be an interesting solution to improve the damper's energy dissipation capability since it increases the journal's effective squeezing surface. While groove feeding has been extensively studied, only a few works have addressed the problem of hole fed dampers. The squeeze film damper model may be able to estimate the pressure at the feed holes as well as the flow into the film. A fundamental issue in the modeling of the hole feed system is the choice of the adequate boundary conditions. Existing published models consider the supply pressure to be constant at a specific section of the hydraulic system. The pressures at the oil injection holes are then obtained via local flow balances taking into account a linear flow resistance across the feed conduits. The model developed in the present work is based on the application of the simplified form of the energy equation commonly used in hydraulics, with approximate pressure drop coefficients. As a boundary condition we impose the power supplied to the pump. The nonlinear hydraulics problem is coupled with the squeeze flow and the Newton-Raphson method is employed to solve the set of nonlinear equations. The influence of the hole feed system on the unbalance response and stability of a Jeffcott rotor is analyzed in regards to the number of feed holes and the power supplied to the pump. The feed system behavior is also studied. A significant number of theoretical and experimental works have been published since the 1960s as the interest in the application of this kind of damper grew strong. As far as the oil film pressure distribution is concerned, the majority of the studies have focused on cavitation modeling, fluid inertia effects, non-Newtonian fluid behavior, and operation with bubbly oil. Despite the consensus about the importance of the damper's boundary conditions, namely the feed system and the leakage conditions, a relatively limited number of works addressed these issues. Regarding the feed system, circumferential groove-fed dampers have already been extensively examined by San Andres (1992) and Arauz and San Andres (1994), who evidenced the influence of the interaction between land and groove flows on the SFD performance. However, for hole fed dampers, a configuration which can turn out to be an interesting way to improve damping capability (Wang and Hahn, 1995), only a few models have been proposed.The hole feed system affects the damper performance in a direct way, in view of the pressure build up resulting from the interaction between the film land flow and the injection holes. An indirect influence can also show up whenever the feeding capability is not high enough to prevent air entrainment into the film, which leads to operation with a bubbly oil (Diaz and San Andres, 2001). Hence, the hole feed system model must be able to provide good estimates of the pressure at the oil injection holes as well as of the flow into the film. Marmol and Vance (1978) proposed a finite difference discretization of ...

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A Model for Squeeze Film Dampers Operating With Air Entrainment and Validation With Experiments

Cited by 57 publications

References 19 publications

A Volume of Fluid Method for Air Ingestion in Squeeze Film Dampers

A Volume of Fluid Method for Air Ingestion in Squeeze Film Dampers

Interaction of Squeeze Film Dampers and Hole Feed Systems and Its Influence on the Dynamics of a Jeffcott Rotor

Interaction of Squeeze Film Dampers and Hole Feed Systems and Its Influence on the Dynamics of a Jeffcott Rotor

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