Hydrodynamic journal bearings are used to support the planetary gears in the transmission system of a Geared Turbo Fan engine, and they operate under severe working conditions, such as misalignment, high speed, and he...Hydrodynamic journal bearings are used to support the planetary gears in the transmission system of a Geared Turbo Fan engine, and they operate under severe working conditions, such as misalignment, high speed, and heavy load. Surface texture is regarded as an effective approach to improve mechanical properties under severe working conditions. However, the effects of surface texture on misaligned journal bearings under severe conditions have not been well studied. Therefore, a thermoelastohydrodynamic(TEHD) lubricating model with a textured and misaligned journal is presented in this study. Solid deformation, heat transfer between oil and the bearing, and heat convection between air and the bearing are considered in the model. The effects of cavitation and viscosity-temperature are also taken into account. The impacts of surface texture parameters and the misalignment angle on lubricating properties are investigated in the model. Results indicate that the bearing lubricating performance is greatly improved by optimal surface texture considering journal misalignment. The maximum oil film pressure and load-carrying capacity of a journal bearing increase with journal misalignment. Meanwhile, the oil film temperature increases sharply while considering misalignment.展开更多
To understand the engine main bearings＇ working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine main bearings are rarely consid...To understand the engine main bearings＇ working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine main bearings are rarely considered simultaneously in most studies. A typical finite element model is selected and the effect of thermoelastohydrodynamic（TEHD） reaction on engine main bearings is investigated. The calculated method of main bearing＇s thermal hydrodynamic reaction and journal misalignment effect is finite difference method, and its deformation reaction is calculated by using finite element method. The oil film pressure is solved numerically with Reynolds boundary conditions when various bearing characteristics are calculated. The whole model considers a temperature-pressure-viscosity relationship for the lubricant, surface roughness effect, and also an angular misalignment between the journal and the bearing. Numerical simulations of operation of a typical I6 diesel engine main bearing is conducted and importance of several contributing factors in mixed lubrication is discussed. The performance characteristics of journal misaligned main bearings under elastohydrodynamic（EHD） and TEHD loads of an I6 diesel engine are received, and then the journal center orbit movement, minimum oil film thickness and maximum oil film pressure of main bearings are estimated over a wide range of engine operation. The model is verified through the comparison with other present models. The TEHD performance of engine main bearings with various effects under the influences of journal misalignment is revealed, this is helpful to understand EHD and TEHD effect of misaligned engine main bearings.展开更多
The thermoelastohydrodynamic performance of an inclined-ellipse dimpled gas face seal is analyzed. The pressure distributions of the gas film and temperature fields of the seal rings and gas film are presented conside...The thermoelastohydrodynamic performance of an inclined-ellipse dimpled gas face seal is analyzed. The pressure distributions of the gas film and temperature fields of the seal rings and gas film are presented considering thermal and elastic distortions.Then, the influences of texturing parameters, including dimple inclination angle and dimple depth, on sealing performance are investigated under different operating parameters such as rotational speeds and seal pressures. The results show that face distortions lead to a decrease in the hydrodynamic effect at high rotational speed. The analysis shows that the opening force can decrease by more than 50% as the rotational speed increases from 0 to 35000 r min^(-1). The influence of face distortion on the seal performance, such as opening force and leakage characteristic, gradually increases with the rotational speed.展开更多
基金co-supported by the National Natural Science Foundation of China(No.51505384)the Natural Science Foundation of Shaanxi Province of China(No.2017JM5032)
文摘Hydrodynamic journal bearings are used to support the planetary gears in the transmission system of a Geared Turbo Fan engine, and they operate under severe working conditions, such as misalignment, high speed, and heavy load. Surface texture is regarded as an effective approach to improve mechanical properties under severe working conditions. However, the effects of surface texture on misaligned journal bearings under severe conditions have not been well studied. Therefore, a thermoelastohydrodynamic(TEHD) lubricating model with a textured and misaligned journal is presented in this study. Solid deformation, heat transfer between oil and the bearing, and heat convection between air and the bearing are considered in the model. The effects of cavitation and viscosity-temperature are also taken into account. The impacts of surface texture parameters and the misalignment angle on lubricating properties are investigated in the model. Results indicate that the bearing lubricating performance is greatly improved by optimal surface texture considering journal misalignment. The maximum oil film pressure and load-carrying capacity of a journal bearing increase with journal misalignment. Meanwhile, the oil film temperature increases sharply while considering misalignment.
基金Supported by National Science and Technology Support Program of China:Vibration and Noise Reduction Technology Research and Application of Bulldozers and Other Earth Moving Machinery(Grant No.2015BAF07B04)
文摘To understand the engine main bearings＇ working condition is important in order to improve the performance of engine. However, thermal effects and thermal effect deformations of engine main bearings are rarely considered simultaneously in most studies. A typical finite element model is selected and the effect of thermoelastohydrodynamic（TEHD） reaction on engine main bearings is investigated. The calculated method of main bearing＇s thermal hydrodynamic reaction and journal misalignment effect is finite difference method, and its deformation reaction is calculated by using finite element method. The oil film pressure is solved numerically with Reynolds boundary conditions when various bearing characteristics are calculated. The whole model considers a temperature-pressure-viscosity relationship for the lubricant, surface roughness effect, and also an angular misalignment between the journal and the bearing. Numerical simulations of operation of a typical I6 diesel engine main bearing is conducted and importance of several contributing factors in mixed lubrication is discussed. The performance characteristics of journal misaligned main bearings under elastohydrodynamic（EHD） and TEHD loads of an I6 diesel engine are received, and then the journal center orbit movement, minimum oil film thickness and maximum oil film pressure of main bearings are estimated over a wide range of engine operation. The model is verified through the comparison with other present models. The TEHD performance of engine main bearings with various effects under the influences of journal misalignment is revealed, this is helpful to understand EHD and TEHD effect of misaligned engine main bearings.
基金supported by the National Natural Science Foundation of China(Grant No.51275473)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LR14E050001)
文摘The thermoelastohydrodynamic performance of an inclined-ellipse dimpled gas face seal is analyzed. The pressure distributions of the gas film and temperature fields of the seal rings and gas film are presented considering thermal and elastic distortions.Then, the influences of texturing parameters, including dimple inclination angle and dimple depth, on sealing performance are investigated under different operating parameters such as rotational speeds and seal pressures. The results show that face distortions lead to a decrease in the hydrodynamic effect at high rotational speed. The analysis shows that the opening force can decrease by more than 50% as the rotational speed increases from 0 to 35000 r min^(-1). The influence of face distortion on the seal performance, such as opening force and leakage characteristic, gradually increases with the rotational speed.
