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Influence of steam leakage through vane, gland, and shaft seals on rotordynamics of high-pressure rotor of a 1,000 MW ultra-supercritical steam turbine

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Abstract

A comparative analysis of the influence of steam leakage through vane, gland, and shaft seals on the rotordynamics of the high-pressure rotor of a 1,000 MW ultra-supercritical steam turbine was performed using numerical calculations. The rotordynamic coefficients associated with steam leakage through the three labyrinth seals were calculated using the control-volume method and perturbation analysis. A stability analysis of the rotor system subject to the steam forcing induced by the leakage flow was performed using the finite element method. An analysis of the influence of the labyrinth seal forcing on the rotordynamics was carried out by varying the geometrical parameters pertaining to the tooth number, seal clearance, and inner diameter of the labyrinth seals, along with the thermal parameters with respect to pressures and temperatures. The results demonstrated that the steam forcing with an increase in the length of the blade for the vane seal significantly influences the rotordynamic coefficients. Furthermore, the contribution of steam forcing to the instability of the rotor is decreased and increased with increases in the seal clearance and tooth number, respectively. The comparison of the rotordynamic coefficients associated with steam leakage through the vane seal, gland seal, and shaft seal convincingly disclosed that, although the steam forcing attenuates the stability of the rotor system, the steam turbine is still operating under safe conditions.

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Abbreviations

A :

unsteady cross-sectional area of the cavity (m2)

A 0 :

steady annular flow area (m2)

C 0 :

orifice contraction coefficient

C 1 :

kinetic energy carry-over coefficient

C r :

steady radial clearance (m)

[C]:

matrix of damping coefficients for the rotor system with seals

h 0 :

stagnant enthalpy (J/kg)

h 0iseal :

enthalpy at the ith orifice (J/kg)

H :

unsteady labyrinth seal radial clearance (m)

\({H_1 \left({\theta, t}\right)}\) :

perturbation clearance (m)

[K]:

matrix of stiffness coefficients for the rotor system with seals

L :

cavity length (m)

m i :

steady-state leakage flow rate at the ith orifice (kg/s)

[M]:

matrix of mass for the rotor system with seals

N :

tooth number

P 0i , P i :

steady and unsteady pressure at the ith cavity (Pa)

P 1i (θ, t):

perturbation pressure in the ith cavity (Pa)

\({\dot{q}_{0i},\dot {q}_i}\) :

steady and unsteady leakage flow rate per unit length (kg/s-m)

\({\dot {q}_{1i}\left({\theta, t}\right)}\) :

perturbation leakage flow rate per unit length (kg/s-m)

R s :

rotor radius (m)

U 0iseal :

velocity at the ith orifice (m/s)

V 0i , V i :

steady and unsteady circumferential velocities in the ith cavity (m/s)

\({V_{1i}\left({\theta,t}\right)}\) :

perturbation circumferential velocities in the ith cavity (m/s)

{Z}:

displacement tensor

\({\{{\dot{Z}}\}}\) :

velocity tensor

\({\{{\ddot{Z}}\}}\) :

acceleration tensor

δ i :

the ith order logarithmic decrement

ρ 0i , ρ i :

steady and unsteady gas density in the ith cavity (kg/m3)

ρ 1i (θ, t):

perturbation gas density in the ith cavity (kg/m3)

ρ 0iseal :

steady gas density at the ith clearance (kg/m3)

τ r0i , τ ri :

steady and unsteady shear stresses at the rotor wall (N/m2)

τ r1i (θ, t):

perturbation shear stress at the rotor wall (N/m2)

τ s0i , τ si :

steady and unsteady shear stresses at the stator wall (N/m2)

τ s1i (θ, t):

perturbation shear stress at the stator wall (N/m2)

θ :

azimuthal position

α r :

dimensionless shear stress length at the rotor wall

α s :

dimensionless shear stress length at the stator wall

ω ci :

the ith order critical rotating speed (rpm)

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Authors and Affiliations

  1. School of Mechanical Engineering, Shanghai Jiao Tong University, Key Laboratory of Power Machinery and Engineering, Ministry of Education, Shanghai, 200240, China

    P. N. Jiang, W. Z. Wang & Y. Z. Liu

  2. Department of R&D, Shanghai Turbine Company, 333 Jiang Chuan Road, Shanghai, 200240, China

    P. N. Jiang

  3. School of Mechanical Engineering, Shanghai Jiao Tong University, State Key Laboratory of Mechanical System and Vibration, Shanghai, 200240, China

    G. Meng

Authors
  1. P. N. Jiang
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  2. W. Z. Wang
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  3. Y. Z. Liu
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  4. G. Meng
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Correspondence to W. Z. Wang.

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Jiang, P.N., Wang, W.Z., Liu, Y.Z. et al. Influence of steam leakage through vane, gland, and shaft seals on rotordynamics of high-pressure rotor of a 1,000 MW ultra-supercritical steam turbine. Arch Appl Mech 82, 177–189 (2012). https://doi.org/10.1007/s00419-011-0547-7

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