Abstract:In this paper, the steady-state characteristics, including film pressure, load capacity, stiffness, misalignment moment of aerostatic bearings considering two types of misalignment (along vertical direction [Formula: see text] and along horizontal direction [Formula: see text]) are studied under pure-static and hybrid condition. The journal misalignment effects on the steady-state characteristics under pure-static condition and hybrid condition are studied comparatively. The results show that the load capacity… Show more
“…By adopting finite difference method, equations (8), (9), and (10) can be turned into equations (11), (12), and (13), and their computational domain is presented in Figure 2. 22 where each coefficient is shown in the Appendix 1. The boundary conditions of equations (11), (12), and (13) are given as follows Figure 2.Computational domain of Reynolds equation and grid structure.…”
Section: Mathematical Modelmentioning
confidence: 99%
“…The boundary conditions of equations (11), (12), and (13) are given as follows Figure 2.Computational domain of Reynolds equation and grid structure. 22 Atmosphere boundary: P 0 ( i ,1) = P 0 ( i,m + 1) = 1;If P0=1,PX=PY=0;P0(ϕ)=P0(ϕ+2π),PX(ϕ)=PX(ϕ+2π) and PY(ϕ)=PY(ϕ+2π)…”
Section: Mathematical Modelmentioning
confidence: 99%
“…The comparison study about misalignment effects under pure-static condition and hybrid condition on the steady-state performances of aerostatic bearings were studied in detail. 22 As mentioned above, the studies of the misalignment effect on the performances of the aerostatic bearings focus on the steady-state performances and do not cover the misalignment effect on the stability threshold of aerostatic bearings-rotor system. The aims of the present research are to decrease the gap and the research can be taken as the further work of Zhang et al 22 that we published previously.…”
Section: Adopted Thementioning
confidence: 99%
“…The comparison study about misalignment effects under pure-static condition and hybrid condition on the steady-state performances of aerostatic bearings were studied in detail. 22…”
Section: Introductionmentioning
confidence: 99%
“…The aims of the present research are to decrease the gap and the research can be taken as the further work of Zhang et al. 22 that we published previously. The misalignment effects along two perpendicular directions on dynamic coefficients are studied comparatively in detail, and then the effects of the misalignment along two perpendicular directions on the stability of journal aerostatic bearing are studied comparatively.…”
Under misalignment condition, the film thickness distribution of aerostatic journal bearings is changed comparing with condition without misalignment, which results in the change of performances of aerostatic journal bearings. In the paper, the effects of misalignment along two perpendicular directions (along the vertical direction θ y and along the horizontal direction θ x) on the dynamic coefficients and stability thresholds of both critical whirl ratio and critical inertial force calculated by the motion equation of rigid rotor-aerostatic journal bearing system are studied comparatively. The results indicate that the dynamic coefficients, critical whirl ratio, and critical inertial force are more sensitive to θ x compared with θ y. Moreover, the stability threshold of whirl ratio reduces with increasing the misalignment degree, while stability threshold of inertial force increases with increasing the misalignment degree.
“…By adopting finite difference method, equations (8), (9), and (10) can be turned into equations (11), (12), and (13), and their computational domain is presented in Figure 2. 22 where each coefficient is shown in the Appendix 1. The boundary conditions of equations (11), (12), and (13) are given as follows Figure 2.Computational domain of Reynolds equation and grid structure.…”
Section: Mathematical Modelmentioning
confidence: 99%
“…The boundary conditions of equations (11), (12), and (13) are given as follows Figure 2.Computational domain of Reynolds equation and grid structure. 22 Atmosphere boundary: P 0 ( i ,1) = P 0 ( i,m + 1) = 1;If P0=1,PX=PY=0;P0(ϕ)=P0(ϕ+2π),PX(ϕ)=PX(ϕ+2π) and PY(ϕ)=PY(ϕ+2π)…”
Section: Mathematical Modelmentioning
confidence: 99%
“…The comparison study about misalignment effects under pure-static condition and hybrid condition on the steady-state performances of aerostatic bearings were studied in detail. 22 As mentioned above, the studies of the misalignment effect on the performances of the aerostatic bearings focus on the steady-state performances and do not cover the misalignment effect on the stability threshold of aerostatic bearings-rotor system. The aims of the present research are to decrease the gap and the research can be taken as the further work of Zhang et al 22 that we published previously.…”
Section: Adopted Thementioning
confidence: 99%
“…The comparison study about misalignment effects under pure-static condition and hybrid condition on the steady-state performances of aerostatic bearings were studied in detail. 22…”
Section: Introductionmentioning
confidence: 99%
“…The aims of the present research are to decrease the gap and the research can be taken as the further work of Zhang et al. 22 that we published previously. The misalignment effects along two perpendicular directions on dynamic coefficients are studied comparatively in detail, and then the effects of the misalignment along two perpendicular directions on the stability of journal aerostatic bearing are studied comparatively.…”
Under misalignment condition, the film thickness distribution of aerostatic journal bearings is changed comparing with condition without misalignment, which results in the change of performances of aerostatic journal bearings. In the paper, the effects of misalignment along two perpendicular directions (along the vertical direction θ y and along the horizontal direction θ x) on the dynamic coefficients and stability thresholds of both critical whirl ratio and critical inertial force calculated by the motion equation of rigid rotor-aerostatic journal bearing system are studied comparatively. The results indicate that the dynamic coefficients, critical whirl ratio, and critical inertial force are more sensitive to θ x compared with θ y. Moreover, the stability threshold of whirl ratio reduces with increasing the misalignment degree, while stability threshold of inertial force increases with increasing the misalignment degree.
In the actual working condition, due to the manufacturing errors, improper installation, load, thermal deformation or other factors can cause the journal surface to produce the form and position errors. The mathematical models are developed that takes into account the form and position errors, the lubrication performance of four-recess capillary restrictor hybrid journal bearings with different journal tilt angles and cylindricities is studied, and the effect of eccentricity on the oil film lubrication performance is analysed. The results show that the dimensionless oil film pressure and loading capacity increase as the journal tilt angle and eccentricity increase considering journal tilt, and the friction coefficient tends to increase and then decrease. Compared with journal alignment, the oil film thickness distorts, the oil film pressure peak shifts to the edge of bearing, and the horizontal tilt has a greater impact on bearing when the journal is tilted. The oil film pressure distribution has no significant change considering cylindricity errors, while the oil film pressure value increases, the loading capacity increases and the coefficient of friction decreases as the cylindricity and eccentricity increase. The research shows that the presence of a certain cylindricity error contributes to the lubrication performance of four-recess capillary restrictor hybrid journal bearings.
In this paper, finite element method is used to calculate the static performance of gas journal bearing, in which rotation speed term is introduced into the stiffness matrix of linear triangular element to realize the performance calculation of the bearing with rotation speed. The results indicate that the average gas film thicknesses corresponding to the maximum load capacity and stiffness, and the minimum attitude angle increase with the growth of orifice diameter. Load capacity and stiffness significantly improved with the increase of rotation speed, eccentricity ratio and supply pressure when the bearing has thin average gas film thickness. Attitude angle increases with the growth of rotation speed, while the growth rate slows down or even decreases at high speed. The most effective way of reducing attitude angle is to increase supply pressure. It can be found that rotation speed affects attitude angle through changing gas pressure difference between two orifices, while other parameters have the same effect by changing gas pressure at orifice outlet.
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