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Experimental and Analytical Investigation of Short Squeeze-Film Damper (SFD) Under Circular-Centered Orbit (CCO) Motion

  • Shaik KarimullaEmail author
  • B. K. Dutta
  • G. Gouthaman
Original Paper
  • 8 Downloads

Abstract

Modern rotating machines operate at higher shaft speeds, crossing a few bending critical speeds, which often induce large dynamic loads on the bearing supports that may increase the rotor orbital whirl motion. Accurate prediction of squeeze-film damper (SFD) forces is the key issue for designers to arrive at a suitable design. An experimental setup was developed with eccentric shaft to find the damper forces. Submerged type damper with relatively large clearance was considered for the present work. It results in higher gap Reynolds number (Re) which varies from 1.5 to 15 in the present case. Four force sensors are used to measure the damper forces and two eddy current probes were used to measure the damper orbit. Circular-centered orbit (CCO) of eccentricity ratio (ε) 0.176 was used in the present work. Theoretical modeling of SFD forces is considered with viscous, inertial, temporal contributions under laminar and turbulent conditions. Modified Reynolds equation with short damper approximation is used to derive the SFD forces for 2π- film. Fourier coefficients of measured forces and displacements are estimated and used to extract the 1× components and phase information. Radial and tangential forces were calculated from the measured total forces to find the contributions of viscous and inertial forces. Experimental forces are compared with theoretically predicted forces and they are in good agreement with the experimental results.

Keywords

Squeeze-film damper Circular-centered orbit Experimentation Short bearing approximation 

Abbreviations

P

Gauge pressure in the damper, N/m2

μ

Dynamic viscosity of the lubricant, N-s/m2

ρ

Density of damper oil, Kg/m3

h

Thickness of the film, m

θ

Circumferential coordinate, rad

t

Time, s

τ

Non-dimensional time, s

R

Radius of damper, m

L

Length of the damper, m

z

Axial coordinate in length direction

φ

Angle from positive Y-axis of the stationary coordinate system (X, Y, Z)

ω

Whirl velocity of the damper cup, rad/s

C

Initial radial clearance in the damper, m

e

Eccentricity (distance between the journal center and damper center), m

ε

Eccentricity ratio, (e/c)

btt

Tangential damping coefficient, N-s/m

brr

Radial damping coefficient, N-s/m

mrrad

Temporal in origin in radial direction

mrnon

Entirely convective in the momentum approximation and dimensionally convective in the energy approximation with small temporal and convective origin in radial direction

mrcen

Mixed temporal and convective origin in radial direction

mttan

Inertia due to tangential acceleration in tangential direction

mtcor

Inertia due to calories’ components in tangential direction

\(\dot{\varepsilon }\)

Radial velocity, rad/s

\(\varepsilon \dot{\varphi }\)

Tangential velocity, rad/s

\(\ddot{\varepsilon }\)

Radial acceleration, rad/s2

\(\varepsilon \ddot{\varphi }\)

Tangential acceleration, rad/s

\(\varepsilon \dot{\varphi }^{2}\)

Centripetal acceleration, rad/s2

\(2\dot{\varepsilon }\dot{\varphi }\)

Carioles acceleration, rad/s2

\(\frac{{\dot{\varepsilon }^{2} }}{\varepsilon }\)

Non-linear radial acceleration (which is not acceleration of the journal) but journal feels its effects due to the inertia effect, rad/s2

\(\left( {\varepsilon \dot{\varphi }} \right)^{2}\)

Non-linear tangential acceleration, rad/s2

fε

Radial component of force acting on damper, N

fφ

Tangential component of force acting on damper cup, N

fT

Total forces, N

Re Gap

Reynolds number, ρC2ω/μ

Notes

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Copyright information

© Krishtel eMaging Solutions Private Limited 2019

Authors and Affiliations

  1. 1.CEL-4, ChTD, Bhabha Atomic Research Centre (BARC)MumbaiIndia
  2. 2.Homi Bhabha National Institute (HBNI)MumbaiIndia
  3. 3.Bhabha Atomic Research Centre (BARC)MumbaiIndia

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