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The misalignment is generally inevitable in the process of machining and assembly of rotor systems with gas foil bearings, but the exploration on this phenomenon is relatively less. Therefore, the purpose of this paper is to carry out the thermo-elastohydrodynamic analysis of the foil bearing with misalignment, especially the inhomogeneous foil bearing.

The rotor is allowed to misalign in two non-rotating directions. Then the static and dynamic performance of the inhomogeneous foil bearing is studied. The thermal-elastohydrodynamic analysis is realized by combining the Reynolds equation, foil deformation equation and energy equation. The small perturbation method is used to calculate the dynamic coefficients, then the critical whirl ratio is obtained.

The gas pressure, film thickness and temperature distribution distort when the misalignment appears. The rotor misalignment can improve the loading capacity but rise the gas temperature at the same time. Furthermore, the rotor misalignment can affect the critical whirl ratio which demonstrates that it is necessary to analyze the misalignment before the rotordynamic design.

The value of this paper is the exploration of the thermo-elastohydrodynamic performance of the inhomogeneous foil bearing with misalignment, the analysis procedure and the corresponding results are valuable for the design of turbo system with gas foil bearings.

The treatment of Reynolds equation when the film thickness is unknown and the center of pressure is known, together with the energy and the bending equation, allows a realistic simulation of the performance of large thrust bearing. In a spring‐supported thrust‐pad bearing the distortion caused by the generated pressure thermal gradient yields a surface profile of opposite shapes. The thermoelastic analysis performed here makes it possible to determine the resultant film shape of the thrust pad.

The purpose of this paper is to acquire sealing properties of supercritical CO₂ (S-CO₂) T-groove seal under ultra-high-speed conditions by thermo-elastohydrodynamic lubrication (TEHL) analysis.

Considering the choked flow effect, the finite difference method is applied to solve the gas state equation, Reynolds equation and energy equation. The temperature, pressure and viscosity distributions of the lubricating film are analyzed, and sealing characteristics is also obtained.

The face distortions induced by increasing rotational speed leads to the convergent face seal gap. When the linear velocity of rotation exceeds 400 m/s, the maximum temperature difference of the sealing film is approximately 140 K, and the viscosity of CO₂ is altered by 17.80%. Near the critical temperature point of CO₂, while the seal temperature increases by 50 K, the opening force of the T-groove non-contact seal enhances by 20% and the leakage rate declines by 80%.

The TEHL characteristics of the T-groove non-contact seal are numerically analyzed under ultra-high-speed, considering the real gas effect and choked flow effect. In the supercritical conditions, the influence of rotational speed, seal temperature, seal pressure and film thickness on sealing performance and face distortions is analyzed.

The current trend of modern industry is to use machineries which rotate at high speed along with the capability of carrying heavy rotor loads. This paper aims at static thermal analysis of two different profiles of non-circular journal bearings – a true elliptical bearing and orthogonal bearing.

The Reynolds equation has been solved through finite difference method to compute the oil film pressure. Parabolic temperature profile approximation technique has been used to solve the energy equation and thus used for computation of various bearing performance characteristics such as thermo-hydrodynamic oil film pressure, temperature, load capacity, Sommerfeld number and power loss characteristics across the bearing. The effect of ellipticity ratio on the bearing performance characteristics has also been obtained for both the elliptical and vertical offset bearing using three different commercially available grades of oil (Hydrol 32, 68 and 100).

It has been observed that the thermo-hydrodynamic pressure and temperature rise of the oil film is less in orthogonal bearing as compared to the true elliptical bearing for same operating conditions. The effect of ellipticity ratio of non-circularity on bearing performance parameters have been observed to be less in case of elliptical bearing as compared to orthogonal bearing. It has been concluded that though the rise in oil film temperature is high for true elliptical bearing, but still it should be preferred over orthogonal profile under study, as it has comparably good load-carrying capacity.

The performance parametric analysis will help the designers to select such kind of non-circular journal bearing for various applications.

This paper aims to acquire the phase distribution and sealing performance of supercritical carbon dioxide (SCO₂) dry gas seals with phase transitions.

The SCO₂ spiral groove dry gas seal is taken as the research object. The finite differential method is applied to solve the governing equations. Furthermore, the phase distribution and the sealing performance are obtained. Compared to the ideal gas model, the effect of phase transitions on sealing performance is also explored.

Vaporization is likely to occur near the inner radius when SCO₂ dry gas seals are operated near the critical point. Whether phase transitions are considered in the model affects the sealing performance seriously. When phase transitions are considered, the sealing performance depends significantly on the working conditions, and unexpected results are produced when inlet conditions approach the critical point.

The numerical model for SCO₂ dry gas seals with phase transitions is established. The phase distribution and the sealing performance of SCO₂ dry gas seals are explored.

The elastic deformation of crankshaft bearing surface will be caused when acted by oil film pressure, which will affect the lubrication performance of crankshaft bearing. The model of the single bearing housing was usually used in the calculation of the elastic deformation of bearing surface. In actual internal combustion engine, the main bearing housing is combined together with engine block; deformation of the main bearing surface will be affected by deformation of the engine block. The purpose of this paper is to investigate the effect of deformation of the whole engine block on the hydrodynamic lubrication performance of main bearings.

The loads of main bearings were calculated by the whole crankshaft beam‐element finite element method. The lubrication of crankshaft bearings was analyzed by dynamic method. The elastic deformations of bearing surface under oil film pressure were calculated by compliance matrix method. The compliance matrix was established by finite element analysis.

It may be not necessary to consider the effect of elastic deformation of bearing surface under film pressure in the lubrication analyses of main bearings for internal combustion engine when the very high calculating accuracy is not required.

The elastohydrodynamic lubrications of crankshaft bearings considering the deformation of engine block were analyzed for the main bearings of an engine. Till now, whether or not the complicated model of the whole cylinder block should be considered to calculate the elastic deformation of main bearing surface in the lubrication analyses of crankshaft main bearings has not been done.

The purpose of this paper is to develop a good calculation model to accurately predict the lubrication characteristic of main bearings of diesel engine and improve the service life.

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the Component Mode Synthesis (CMS) method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an elastohydrodynamic (EHD)-mixed lubrication model of the main bearings for the diesel engine is developed and researched with the finite volume method and the finite element method.

Obviously, the mixed lubrication of bearings is normal, while full hydrodynamic lubrication is transient. The results show that under the whole flexible block model, maximum oil film pressure, maximum asperity contact pressure and radial shell deformation decrease, while minimum oil film thickness increases. Oil flow over edge decreases, and so does friction loss. Therefore, coordination deformation ability of whole engine block is favorable to mean load. In the whole block model, friction contact happens on both upper shell and lower shell positions. In addition, average oil film fill ratio at the key position becomes smaller in the whole engine block model, and consequently increases the chances of cavitations erosion more. So, wearing resistance of both upper and lower shells and anti-cavitations erosion ability must be enhanced simultaneously.

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the CMS method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an EHD-mixed lubrication model of the main bearings for the diesel engine is built, which can predict the lubrication of journal bearings more accurately.

The paper aims to analyze the evolution of the lubrication regime by studying the variation of friction coefficient with the rotational speed of the shaft and the impact of the applied load in the starting phase of a cylindrical journal bearing. The paper also aims to ensure that the oil layer is large enough for the rough edges of the outer layer of the bushing and the shaft cannot come into contact. The bearing is made of steel backing material and babbitted (88 per cent tin) on its inner surface.

A numerical analysis is performed taking into account the thermal effect to better predict the operating performance of a hydrodynamic plain cylindrical journal bearing during the start-up and observe the variation of the heat production in bushing inner surface. The flow is modeled based on the Reynolds equation and discretized using the finite volume method.

The evolutions of the start-up speeds of the bearing have remarkable influence on friction torque; average temperature and dissipated power increased with increasing speed and increasing load, but the maximum pressure and the eccentricity decreased with the increase of the start-up speed. The friction coefficient, minimum film thickness and attitude angle increase with elevation of start-up speed.

For the start-up speed of 750, 1,000 and 1,800 rpm and an applied load of 1,000 N, the regime of lubrication of the bearing passes the hydrodynamic regime to the mixed regime; therefore, during start-up and under heavy loads, the bearing must move very quickly at these speeds to avoid contact of the inner surface of the bearing and the shaft.

This paper aims to study the impact of transient velocity changes on sealing performance during reciprocating sealing processes.

Establish a model of transient mixed lubrication, solve the transient Reynolds equation, consider the effect of temperature rise at the seal interfaces, and determine the behavior of the seal interfaces, such as film thickness and fluid pressure. Evaluation with friction and leakage rate, calculate the variation of sealing performance with reciprocating velocity under different working conditions, and verify it through bench experiments.

Within a reciprocating stroke, the frictional force decreases with increasing velocity, and the frictional force of the outstroke is greater than that of the instroke; at the time of the stroke transition, the fluid pressure is smallest and the rough peak contact pressure is greatest. At present, the dynamic pressure effect of fluids is the largest, and the friction force also increases, which increases the risk of material wear and failure. Friction and leakage increase with increasing pressure and root mean square roughness. As temperature increases, friction increases and leakage decreases. In studying the performance variations of seal components through a reciprocating sealing experiment, it was found that the friction force decreases with increasing velocity, which is consistent with the calculated results and more similar to the calculated results considering the temperature rise.

This study provides a reference for the study of transient sealing performance.