Sfdflexs Computational Analyses of Squeeze Film Dampers

The TAMU Turbomachinery Research Consortium funded the development of computational analysis programs for squeeze film dampers (SFDs)

sfdfem	calculates fluid film forces and damping force coefficients (Ctt,Crt) in finite length squeeze film dampers executing circular centered motions (1986)
sfdflexs	calculates instantaneous fluid film forces for arbitrary journal motions and circular centered orbits in multiple-(flexure) pad integral squeeze film dampers (1996).

Analysis: The fluid flow in the squeeze film lands is described by Reynolds equation for generation of the hydrodynamic squeeze film pressure due to arbitrary motions of the damper journal center.Flow relations for end seals, i.e., local seal: end seal without large axial groove. global seal: end seal with large axial plenum.

Flow model: Laminar and isothermal flow
Governing Equations: Reynolds equation
Numerical method of solution: finite elements
Limitations and Restrictions: Isothermal squeeze film dampers without fluid inertia
Cavitation model: Gumbel condition (chop negative pressures) or Reynolds condition (dP/dx=0) at cavitation inception zone

Input- MS Excel® Graphical User Interface - worksheet
Output - MS Excel® Graphical User Interface - worksheet - Field data files for plotting pressure and film thickness as Z=Z(X,Y) surfaces.

Language: FORTRAN77 Source code provided.

Users: Texas A&M Turbomachinery Research Consortium members.

Availability: Supplied to industrial members of TAMU Turbomachinery Research Consortium free of charge

Other software based on approximate solutions to analytical models:

COEFCCO-CL2	calculates the damping and inertia force coefficients for finite length squeeze film dampers (SFDs) executing circular centered motions within the bearing clearance. The model includes dampers with open ends and (locally) sealed ends with asymmetric discharge coefficients.
CIJLDSFD	calculates the linearized damping and inertia force coefficients for finite length open ends squeeze film dampers (SFDs) executing small amplitude motions about an equilibrium position within the bearing clearance.

Method: Analytical approximate solution to flow equations including fluid inertia. Accurate Correction factors to long SFD model are given in closed form. Fully Developed, laminar isothermal-isoviscous flow model
Governing Equations: Continuity and averaged-inertia momentum equations for squeeze film flow. Flow relations for end seals (local type).
Cavitation model: cut negative pressures
Limitations and Restrictions: Isothermal SFDs with squeeze film Reynolds numbers (Res) < 20. Full film or pi-film cavitation models
Input- MS Excel® Graphical User Interface - worksheet
Output - MS Excel® Graphical User Interface – worksheet: Table of force coefficients vs. journal orbit radius or journal static center.