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A rotordynamic analysis of an annular honeycomb seal using a two-control volume model

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Abstract

Basic equations are derived for an annular honeycomb gas seal based on a two-control volume model. The two-control volume model includes additionally a transient radial velocity component at a porous honeycomb stator surface while a conventional one-control volume model takes only the axial and the circumferential velocity components in a seal. By using a perturbation analysis and a numerical integration method, the basic equations are solved to yield the force and the corresponding dynamic coefficients developed by the seal. The two-control volume model analysis is compared to both the one-control volume model and experimental results. The comparisons show that the two-control volume analysis generally improves the predictions of rotordynamic coefficients, especially, for direct damping.

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Abbreviations

b :

Honeycomb cell width (mm)

C, c :

Direct and cross-coupled damping coefficients (N · s/mm)

C e :

Nominal radial clearance at seal entrance (mm)

C x :

Nominal radial clearance at seal exit (mm)

C v :

Specific heat at constant volume

d :

Honeycomb cell depth (mm)

D h :

Hydraulic diameter (m)

e n :

Surface roughness height (m)

f :

Fanning friction factor

F x ,F y :

Components of seal reaction force (N)

H :

Local film thickness (mm)

K, k :

Direct and cross-coupled stiffness (N/mm)

L :

Seal length (m)

Ma :

Mach number

P :

Pressure (bar)

R :

Seal radius (m)

Re :

Reynolds number

T :

Temperature (oK)

t :

Time (s)

U s ,U r :

Bulk-flow velocities relative to stator and rotor of Eq. (6)

U z ,U g :

Fluid velocity in the axial and circum-ferential direction (m/s)

V :

Fluid velocity in the radial direction (m/s)

X,Y :

Rotor displacements from its static position (m)

ε:

Eccentricity perturbation (m)

π:

Fluid density (kg/m3)

ω:

Rotor angular velocity (rad/s)

d, b :

Reservoir and sump

γ, s :

Rotor and stator

z, ϕ:

Axial and circumferential directions

0, 1:

Zeroth and first-order perturbations

References

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Authors and Affiliations

  1. Architectural Equipment Engineering Department, Kyung-won University, Sungnam, Korea

    T. W. Ha

  2. Mechanical Engineering Department, Turbomachinery Laboratory, Texas A & M University, Texas, USA

    D. W. Childs

Authors
  1. T. W. Ha
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  2. D. W. Childs
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Ha, T.W., Childs, D.W. A rotordynamic analysis of an annular honeycomb seal using a two-control volume model. KSME Journal 10, 332–340 (1996). https://doi.org/10.1007/BF02942642

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  • DOI: https://doi.org/10.1007/BF02942642

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