In this study,we designed an oil-filled motor that can be used at full-ocean depths,and investigated the friction losses caused by the rotating seal and the properties of the oil.The direct current(DC)motor is encapsu...In this study,we designed an oil-filled motor that can be used at full-ocean depths,and investigated the friction losses caused by the rotating seal and the properties of the oil.The direct current(DC)motor is encapsulated in an aluminum alloy housing.A rubber diaphragm is used to balance the internal and external pressures so that the motor can work on the seabed without pressure difference.To study the resistance caused by the rotating seal,a numerical model of the Glyd ring and the rotating shaft was established.Results from a rotational torque test agreed with those from numerical analysis.The kinematic viscosity of four oils was measured at 1-25℃.Oil bath experiments in an incubator showed that the resistance from oil is highly correlated with its dynamic viscosity.Dimethicone appears to be very suitable as an insulating oil for these motors.The working characteristics of the motor were tested in a high-pressure chamber.The results showed that the motor needs to overcome higher oil resistance under higher pressure.A prototype of a pressure-adaptive motor was designed and applied successfully in the hadal zone at a water depth of more than 10000 m.展开更多
We focus on the friction loss measurement and reduction of the timing belt guide plates of a fourcylinder gasoline engine. To minimize the friction loss caused by the dynamic friction of the guide plates during timing...We focus on the friction loss measurement and reduction of the timing belt guide plates of a fourcylinder gasoline engine. To minimize the friction loss caused by the dynamic friction of the guide plates during timing belt motion and improve the efficiency of the internal combustion engine(ICE), we adopt four different plastic materials in fabricating the guide plates. With controlled engine boundary conditions and operational modes, an AVL electric dynamometer is used to measure the output of the engine. The results indicate that selecting polytetrafluoroethylene(PTFE) as the additive in fabricating the guide plates can effectively reduce the friction loss, so that the output torque and output power of the engine can be improved, thus reducing fuel consumptions. This work also has positive impact on the efficiency optimization of similar ICEs.展开更多
To improve the power density and simplify the seal structure,the Wet-Type Permanent Magnet Synchronous Motor(WTPMSM)technique has been applied to aerospace Electro-Hydrostatic Actuators(EHA).In a WTPMSM,the stator and...To improve the power density and simplify the seal structure,the Wet-Type Permanent Magnet Synchronous Motor(WTPMSM)technique has been applied to aerospace Electro-Hydrostatic Actuators(EHA).In a WTPMSM,the stator and the rotor are both immersed in the aviation hydraulic oil.Although the heat dissipation performance of the WTPMSM can be enhanced,the aviation hydraulic oil will cost an extra oil frictional loss in the narrow airgap of the WTPMSM.This paper proposes an accurate oil frictional loss model for the WTPMSM,in which the wide speed range(0–20 kr/min)and the narrowness of the airgap(0.5–1.5 mm)are its features.Firstly,the mechanism of the oil frictional loss in the airgap of the WTPMSM is revealed.Then an accurate oil frictional loss model is proposed considering the nonlinear influence caused by the Taylor vortex.Furthermore,the influence of motor dimensions on oil frictional loss is analyzed.Finally,the proposed oil frictional loss model is verified by experiments,which provides a guideline for engineers to follow in the WTPMSM design.展开更多
According to the dimensional tolerances on hydrodynamic journal bearing system, a nonlinear oil film force model was established,and the Reynolds' equation was solved by adopting finite difference method. In order...According to the dimensional tolerances on hydrodynamic journal bearing system, a nonlinear oil film force model was established,and the Reynolds' equation was solved by adopting finite difference method. In order to fulfill different dimensional tolerances in the system,adopting 2kfactor design and using the eccentricity ratio corresponding to the stability critical curve,the effects of the friction power loss brought by the dimensional tolerances of the dynamic viscosity,bearing width,bearing diameter and journal diameter were analyzed. The effect on dynamic characteristics of the hydrodynamic journal bearing system was quantitatively analyzed,and the nonlinear dynamic analysis, modeling and calculation methods were studied while considering the manufacturing tolerances. The results show that in contrast to the impacts of the tolerances in journal diameter,dynamic viscosity and bearing width,the bearing diameter tolerance would lead to the rise in the power loss, and the dimensional tolerances have different degrees of impacts on the journal bearing system. The friction power loss decreased as the eccentricity ratio increased, and when the eccentricity ratio was 0. 695 the power loss came to the minimum.The investigation would find the best solution and reduce energy consumption,then control varieties of nonlinear dynamical behavior effectively,and provide a theoretical basis for hydrodynamic journal bearing system in parameter design.展开更多
In Underbalanced Drilling(UBD)method,it is difficult to predict the equivalent circulation density due to co-existence of three phases which are air,cuttings and drilling fluid.This study presents the application of a...In Underbalanced Drilling(UBD)method,it is difficult to predict the equivalent circulation density due to co-existence of three phases which are air,cuttings and drilling fluid.This study presents the application of a developed model inspired from a novel intelligent algorithm namely radial basis function optimized by genetic algorithm(GA-RBF)algorithm to calculate frictional pressure loss of two-phase gasified drilling fluid flow along with cutting as the third phase in inclined wellbore portions.The suggested approach was conducted to extensive data reported in literature and was based on Rate of Penetration(ROP),wellbore inclination,pipe rotation and in situ flow rate of each phase.The results of this study show that the proposed model could reproduce the experimental frictional pressure loss data to an acceptable accuracy due to high correlation coefficient(R^(2)>0.99)and very small values of average absolute relative deviation(AARD)(2.166726),standard deviation(STD)(0.038222)and root mean square error(RMSE)(0.008783).Results of this study could couple with commercial drilling simulators to accurately predict the frictional pressure loss of three phase flow.展开更多
This study introduces a prediction method for bearing friction power loss,focusing on the interplay of bearing skidding and cage motion stability on the tribological properties of ball bearings.The internal friction s...This study introduces a prediction method for bearing friction power loss,focusing on the interplay of bearing skidding and cage motion stability on the tribological properties of ball bearings.The internal friction source is first identified in eight forms according to the interaction analysis among bearing components.Then,the ring flexibility generated by the assembly state of a rotor-bearing system and the cage flexibility caused by the centrifugal effect are considered,and the effects of the spatial displacement of outer ring and contact force on the outer ring deformation are also analyzed.Furthermore,the traction effect of the ball-raceway and the hydrodynamic lubrication of the cage-guiding ring are discussed to establish an improved bearing dynamic model.The validity and reliability of the present method are confirmed through a comparative analysis with experimental data.Finally,the relationships between the dynamic behavior and friction power loss are investigated.The results highlight the critical role of the friction loss of bearing components subjected to lubricant viscosity resistance and the sliding friction loss of the cage-guiding ring in determining the total tribological properties.The dynamic behavior can also be optimized by adjusting the bearing preload and cage structure to effectively weaken the bearing friction power loss.展开更多
基金supported by the National Key R&D Program of China(No.2018YFC0310601)the Strategic Priority Research Program of the Chinese Academy of Science(No.XDA22000000)+1 种基金the National Key Research and Development Program of China(Nos.2016YFC0300800 and 2017YFC006500)the Key Program of Sanya Yazhouwan,China。
文摘In this study,we designed an oil-filled motor that can be used at full-ocean depths,and investigated the friction losses caused by the rotating seal and the properties of the oil.The direct current(DC)motor is encapsulated in an aluminum alloy housing.A rubber diaphragm is used to balance the internal and external pressures so that the motor can work on the seabed without pressure difference.To study the resistance caused by the rotating seal,a numerical model of the Glyd ring and the rotating shaft was established.Results from a rotational torque test agreed with those from numerical analysis.The kinematic viscosity of four oils was measured at 1-25℃.Oil bath experiments in an incubator showed that the resistance from oil is highly correlated with its dynamic viscosity.Dimethicone appears to be very suitable as an insulating oil for these motors.The working characteristics of the motor were tested in a high-pressure chamber.The results showed that the motor needs to overcome higher oil resistance under higher pressure.A prototype of a pressure-adaptive motor was designed and applied successfully in the hadal zone at a water depth of more than 10000 m.
基金the Shanghai Automotive Industry Science and Technology Development Foundation(No.1614)
文摘We focus on the friction loss measurement and reduction of the timing belt guide plates of a fourcylinder gasoline engine. To minimize the friction loss caused by the dynamic friction of the guide plates during timing belt motion and improve the efficiency of the internal combustion engine(ICE), we adopt four different plastic materials in fabricating the guide plates. With controlled engine boundary conditions and operational modes, an AVL electric dynamometer is used to measure the output of the engine. The results indicate that selecting polytetrafluoroethylene(PTFE) as the additive in fabricating the guide plates can effectively reduce the friction loss, so that the output torque and output power of the engine can be improved, thus reducing fuel consumptions. This work also has positive impact on the efficiency optimization of similar ICEs.
基金This work was supported in part by National Natural Science Foundation of China(Nos.52177028 and U2141226)in part by Major Program of the National Natural Science Foundation of China(No.51890882)in part by Aeronautical Science Foundation of China(No.201907051002).
文摘To improve the power density and simplify the seal structure,the Wet-Type Permanent Magnet Synchronous Motor(WTPMSM)technique has been applied to aerospace Electro-Hydrostatic Actuators(EHA).In a WTPMSM,the stator and the rotor are both immersed in the aviation hydraulic oil.Although the heat dissipation performance of the WTPMSM can be enhanced,the aviation hydraulic oil will cost an extra oil frictional loss in the narrow airgap of the WTPMSM.This paper proposes an accurate oil frictional loss model for the WTPMSM,in which the wide speed range(0–20 kr/min)and the narrowness of the airgap(0.5–1.5 mm)are its features.Firstly,the mechanism of the oil frictional loss in the airgap of the WTPMSM is revealed.Then an accurate oil frictional loss model is proposed considering the nonlinear influence caused by the Taylor vortex.Furthermore,the influence of motor dimensions on oil frictional loss is analyzed.Finally,the proposed oil frictional loss model is verified by experiments,which provides a guideline for engineers to follow in the WTPMSM design.
基金National Natural Science Foundations of China(No.11272100,No.50865001)
文摘According to the dimensional tolerances on hydrodynamic journal bearing system, a nonlinear oil film force model was established,and the Reynolds' equation was solved by adopting finite difference method. In order to fulfill different dimensional tolerances in the system,adopting 2kfactor design and using the eccentricity ratio corresponding to the stability critical curve,the effects of the friction power loss brought by the dimensional tolerances of the dynamic viscosity,bearing width,bearing diameter and journal diameter were analyzed. The effect on dynamic characteristics of the hydrodynamic journal bearing system was quantitatively analyzed,and the nonlinear dynamic analysis, modeling and calculation methods were studied while considering the manufacturing tolerances. The results show that in contrast to the impacts of the tolerances in journal diameter,dynamic viscosity and bearing width,the bearing diameter tolerance would lead to the rise in the power loss, and the dimensional tolerances have different degrees of impacts on the journal bearing system. The friction power loss decreased as the eccentricity ratio increased, and when the eccentricity ratio was 0. 695 the power loss came to the minimum.The investigation would find the best solution and reduce energy consumption,then control varieties of nonlinear dynamical behavior effectively,and provide a theoretical basis for hydrodynamic journal bearing system in parameter design.
文摘In Underbalanced Drilling(UBD)method,it is difficult to predict the equivalent circulation density due to co-existence of three phases which are air,cuttings and drilling fluid.This study presents the application of a developed model inspired from a novel intelligent algorithm namely radial basis function optimized by genetic algorithm(GA-RBF)algorithm to calculate frictional pressure loss of two-phase gasified drilling fluid flow along with cutting as the third phase in inclined wellbore portions.The suggested approach was conducted to extensive data reported in literature and was based on Rate of Penetration(ROP),wellbore inclination,pipe rotation and in situ flow rate of each phase.The results of this study show that the proposed model could reproduce the experimental frictional pressure loss data to an acceptable accuracy due to high correlation coefficient(R^(2)>0.99)and very small values of average absolute relative deviation(AARD)(2.166726),standard deviation(STD)(0.038222)and root mean square error(RMSE)(0.008783).Results of this study could couple with commercial drilling simulators to accurately predict the frictional pressure loss of three phase flow.
基金the Key R&D Program of the Ministry of Industry and Information Technology(No.TC220H05VHZ)the National Natural Science Foundation of China(No.52175250).
文摘This study introduces a prediction method for bearing friction power loss,focusing on the interplay of bearing skidding and cage motion stability on the tribological properties of ball bearings.The internal friction source is first identified in eight forms according to the interaction analysis among bearing components.Then,the ring flexibility generated by the assembly state of a rotor-bearing system and the cage flexibility caused by the centrifugal effect are considered,and the effects of the spatial displacement of outer ring and contact force on the outer ring deformation are also analyzed.Furthermore,the traction effect of the ball-raceway and the hydrodynamic lubrication of the cage-guiding ring are discussed to establish an improved bearing dynamic model.The validity and reliability of the present method are confirmed through a comparative analysis with experimental data.Finally,the relationships between the dynamic behavior and friction power loss are investigated.The results highlight the critical role of the friction loss of bearing components subjected to lubricant viscosity resistance and the sliding friction loss of the cage-guiding ring in determining the total tribological properties.The dynamic behavior can also be optimized by adjusting the bearing preload and cage structure to effectively weaken the bearing friction power loss.
