“…The bearing geometric structure parameters and operating conditions of the computational model are listed in Table 1. Figure 7(a) is taken from the results of Wang et al., 22 and Figure 7(b) is the calculated result of the present study. As can be seen, Figure 7(a) and (b) shows similar pressure distribution in both the circumferential and axial directions, which indicates the validity of the computational model.…”
This paper studies the effect of angular misalignment on the dynamic characteristics of externally pressurized air journal bearing with four degrees of freedom. The linear perturbation method is applied to the Reynolds equation to obtain the steady-state equation and perturbation equations, and then the finite difference method and an iterative method are used to solve the Reynolds equation. Various eccentricity ratios and rotating speeds are taken into considerations for the comparisons of dynamic stiffness coefficients and damping coefficients of the air journal bearing under different tilt angles. In addition, the influences of perturbation frequency ratio on the dynamic performances of the air journal bearing are also estimated.
“…The bearing geometric structure parameters and operating conditions of the computational model are listed in Table 1. Figure 7(a) is taken from the results of Wang et al., 22 and Figure 7(b) is the calculated result of the present study. As can be seen, Figure 7(a) and (b) shows similar pressure distribution in both the circumferential and axial directions, which indicates the validity of the computational model.…”
This paper studies the effect of angular misalignment on the dynamic characteristics of externally pressurized air journal bearing with four degrees of freedom. The linear perturbation method is applied to the Reynolds equation to obtain the steady-state equation and perturbation equations, and then the finite difference method and an iterative method are used to solve the Reynolds equation. Various eccentricity ratios and rotating speeds are taken into considerations for the comparisons of dynamic stiffness coefficients and damping coefficients of the air journal bearing under different tilt angles. In addition, the influences of perturbation frequency ratio on the dynamic performances of the air journal bearing are also estimated.
“…The pressure field in the gas film is described with the Reynolds equation as follows 25,38 where p is pressure, ϕ and z are the computational axes, u and w are the circumferential velocity and axial velocity of the piston, m·in is the mass flow rate 37 at the orifice inlet described by equation (3) below, δi=1 with orifice and δi=0 without the orifice. ℜ is ideal gas constant, T is the atmospheric temperature, and h is the gap thickness 39 expressed in equation (4).…”
Section: Mathematical Modelingmentioning
confidence: 99%
“…The initial and boundary conditions of the pressure field in the gas film are shown in Figure 3, which can be expressed in the time domain K as follows 37,38,43 Figure 3.Computational domain of the journal bearing.…”
Section: Mathematical Modelingmentioning
confidence: 99%
“…The bearing load force components in x and y directions are written in equations (14) to (17) as given in literature 38,44 …”
Section: Mathematical Modelingmentioning
confidence: 99%
“…Friction force in the axial direction FfZ should be calculated as follows (similar to the equation in literature 38,44 ) …”
In this work, the backflow phenomenon exhibited in the gas journal bearings is investigated. The effect of operational parameters such as eccentricity ratio ɛ, axial velocity of the bearing vz, misalignment angles [Formula: see text] and [Formula: see text] on the backflow behavior, and load force and axial friction force of the bearing are studied numerically. The differential transformation method and finite difference method are utilized to solve the dimensionless Reynolds equations required in the analysis. The performance parameters such as pressure distribution, gas flow rate, load force, and axial friction force are examined in the numerical simulations. The investigation reveals that when the bearing is operated in normal working zone, the load force F increases significantly with an increase in eccentricity ɛ; however, F may only increase slightly when the bearing operates in the backflow zone. It is suggested that the pressure Ps should be set greater than 5.0, Pc smaller than or equal to 3.0 to avoid the backflow behavior. The axial friction force [Formula: see text] is largely determined by the pressure [Formula: see text], and increases as pressure Pc increases.
As the progress of the high-speed performance requirement for porous gas journal bearings continuing, the aerodynamic effect, which plays a key role in the state of lubrication, causes the porous gas journal bearings being gradually to be used as hybrid bearings. This paper firstly presents a theoretical analysis on the lubrication mechanism of the hybrid bearings. The gas flow in the porous and clearance is modelled by using the mass continuity equation. Two
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