Abstract
This paper studies the nonlinear dynamic characteristics of a flexible rotor supported by self-acting gas bearings theoretically. The multiple degree freedom model of flexible rotor is established by the finite element method and analyzed coupled with the transient gas lubricated Reynolds equation by employing the forecasting orbit method. The Reynolds equation is solved by the alternating direction implicit method and the dynamic response of the rotor is calculated by the Newmark integral method. To settle the problem that the two kinds of transient solving processes (transient Reynolds equation for bearing and transient equation of motion for rotor) cannot be solved simultaneously, which arises from the fact that they need each other’s results as their initial values, the multi-field coupling algorithm based on the forecasting method is proposed and applied in this paper. By employing the numerical method, the rotor trajectory diagram, phase diagram, frequency spectrum, power spectrum, bifurcation diagram, and vibration mode diagram were obtained. It is to note that the dynamic characteristics of self-acting gas bearing–rotor system and whirling instability of the system could be depicted successfully. This would establish the foundation for contributing to a further understanding of the gas bearing–flexible rotor system.
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Abbreviations
- c :
-
average air film thickness
- e :
-
eccentricity
- e x ,e y :
-
eccentricity in x, y direction
- h :
-
air film thickness
- l T :
-
the length of the rotor element
- p :
-
air film pressure
- p a :
-
atmospheric pressure
- t :
-
time
- x,y,z :
-
coordinates
- A :
-
the section area of the rotor
- F x ,F y :
-
the gas film forces act on the rotor
- F n ,F n+1 :
-
the gas film forces at time n and n+1
- H :
-
dimensionless air film thickness
- H n :
-
gas film thickness function at time n
- \(H_{\mathrm{forecast}}^{n + 1}\) :
-
gas film thickness function at time n+1 by forecasting
- I y :
-
moment of the inertia for rotor
- L :
-
the length of the bearing
- NX :
-
the mesh number of circumferential direction
- NZ :
-
the mesh number of bearing length direction
- P :
-
dimensionless pressure
- P n+1 :
-
dimensionless pressure at time n+1
- Q :
-
the square of the P; Q=P 2
- R :
-
radius of the bearing
- W :
-
load capacity
- ε :
-
the eccentricity ratio
- η :
-
the dynamic viscosity of air
- θ :
-
the angular coordinate
- θ 0 :
-
attitude angle
- ξ :
-
the dimensionless coordinates in length direction
- ρ :
-
the air density under arbitrary pressure
- ρ a :
-
the air density under atmospheric pressure
- ρ r :
-
the density of the rotor
- τ :
-
the dimensionless time
- φ :
-
the attitude angle
- ω :
-
rotating angular speed of the shaft
- Λ :
-
the bearing number
- Φ s :
-
shear factor for the rotor
References
Yang, P., Zhu, K.Q., et al.: On the nonlinear stability of self-acting gas journal bearings. Tribol. Int. 42(1), 71–76 (2009)
Sternlicht, B.: Elastic and damping properties of cylindrical journal bearings. J. Basic Eng. 81, 101–108 (1959)
Rentzepis, G.M., Sternlicht, B.: On the stability of rotors in cylindrical journal bearings. J. Basic Eng. 84(3), 521–532 (1961)
Ausman, J.S.: An improved analytical solution for self-acting, gas-lubricated journal bearings of finite length. J. Basic Eng. 83(2), 188–194 (1961)
Lund, J.W.: The stability of an elastic rotor in journal bearings with flexible, damped supports. J. Appl. Mech. 87, 911–920 (1965)
Castelli, V., Elrod, H.G.: Solution of the stability problem for 360 degree self-acting, gas-lubricated bearing. J. Basic Eng. 87(1), 199–212 (1961)
Castelli, V., Stevenson, C.H.: A Semi-implicit Numerical Method for Treating the Time Transient Gas Lubrication Equation. Mechanical Technology Inc, New York, TID-23853 (1967)
Dimofte, F.: Fast methods to numerically integrate the Reynolds equation for gas fluid films. New York, NASA Technical Memorandum, 105415 (1992)
Bou-sa, B., Grau, G., Iordanoff, I.: On nonlinear rotor dynamic effects of aerodynamic bearings with simple flexible rotors. J. Eng. Gas Turbine Power 130(1), 012503 (2008)
Wang, C., Jang, M., Yeh, Y.: Bifurcation and nonlinear dynamic analysis of a flexible rotor supported by relative short gas journal bearings. Chaos Solitons Fractals 32(2), 566–582 (2007)
Wang, C.C.: Application of a hybrid method to the nonlinear dynamic analysis of a flexible rotor supported by a spherical gas-lubricated bearing system. Nonlinear Anal. 70(5), 2035–2053 (2009)
Wang, C.C.: Bifurcation and nonlinear analysis of a flexible rotor supported by a relative short spherical gas bearing system. Commun. Nonlinear Sci. Numer. Simul. 15(9), 2659–2671 (2010)
Frederic, J.B.: A monolithical fluid-structure interaction algorithm applied to the piston problem. Comput. Methods Appl. Mech. Eng. 167, 369–391 (1998)
Michler, C., Hulshoff, S.J., van Brummelen, E.H., et al.: A monolithic approach to fluid-structure interaction. Comput. Fluids 33, 839–848 (2004)
Longatte, E., Verreman, V., Bendjeddou, Z., et al.: Comparison of strong and partitioned fluid structure code coupling methods. In: ASME, Pressure Vessels and Piping Division (Publication) PVP, v 4, Proceedings of the ASME Pressure Vessels and Piping Conference 2005—Fluid-Structure Interaction, PVP2005, pp. 447–455 (2005)
Etienne, S., Pelletier, D., Garon, A.: An updated lagrangian monolithic formulation for steady-state fluid-structure interaction problems. In: 43rd AIAA Aerospace Sciences Meeting and Exhibit—Meeting Papers, pp. 239–253 (2005)
Piperno, S., Farhat, C., Larrouturou, B.: Partitioned procedures for the transient solution of coupled aeroelastic problems—Part I: Model problem, theory and two-dimensional applications. Comput. Methods Appl. Mech. Eng. 124, 79–112 (1995)
Piperno, S.: Explicit/implicit fluid/structure staggered procedures with a structural predictor and fluid subcycling for 2d inviscid aeroelastic simulations. Int. J. Numer. Methods Fluids 25, 1207–1226 (1997)
Farhat, C., Lesoinne, C., Letallec, P.: Load and motion transfer algorithms for fluid/structure interaction problems with non-matching discrete interfaces: momentum and energy conservation, optimal discrimination and application to aeroelasticity. Comput. Methods Appl. Mech. Eng. 157(1–2), 95–114 (1998)
Piperno, S.: Partitioned procedures for the transient solution of coupled aeroelastic problems—Part II: Energy transfer analysis and three-dimensional applications. Comput. Methods Appl. Mech. Eng. 190(24–25), 3147–3170 (2001)
Malik, M., Bert, C.W.: Differential quadrature solutions for steady-state incompressible and compressible lubrication problems. J. Tribol. 116(2), 296–302 (1994)
Reynolds, D.B., Gross, W.A.: Experimental investigation of whirl in self-acting air-lubricated journal bearings. Tribol. Trans. 5(2), 392–403 (1962)
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Zhang, Gh., Sun, Y., Liu, Zs. et al. Dynamic characteristics of self-acting gas bearing–flexible rotor coupling system based on the forecasting orbit method. Nonlinear Dyn 69, 341–355 (2012). https://doi.org/10.1007/s11071-011-0268-z
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DOI: https://doi.org/10.1007/s11071-011-0268-z