In the paper, a solution of one dimensional fore region pressure build up is put forward. The performance of spring supported thrust bearing is carried out with 3 dimensional thermo elasto hydrodynamic (TEHD) lub...In the paper, a solution of one dimensional fore region pressure build up is put forward. The performance of spring supported thrust bearing is carried out with 3 dimensional thermo elasto hydrodynamic (TEHD) lubrication theory inclusive of inlet pressure build up, thermal elastic distortion of pad and thermal effect. The effects of fore region pressure build up and the variation of some operating conditions on the performance of the pad are studied.展开更多
Thrust bearing is a key component of the propulsion system of a ship. It transfers the propulsive forces from the propeller to the ship＇s hull, allowing the propeller to push the ship ahead. The performance of a thru...Thrust bearing is a key component of the propulsion system of a ship. It transfers the propulsive forces from the propeller to the ship＇s hull, allowing the propeller to push the ship ahead. The performance of a thrust bearing pad is critical. When the thrust bearing becomes damaged, it can cause the ship to lose power and can also affect its operational safety. For this paper, the distribution of the pressure field of a thrust pad was calculated with numerical method, applying Reynolds equation. Thrust bearing properties for loads were analyzed, given variations in outlet thickness of the pad and variations between the load and the slope of the pad. It was noticed that the distribution of pressure was uneven. As a result, increases of both the outlet thickness and the slope coefficient of the pad were able to improve load beating capability.展开更多
Common fluid film bearing issues(mainly high bearing temperature)preventing reliable operation of turbomachinery will be addressed.Atheoretical review of radial and thrust bearing performance will be included for a ba...Common fluid film bearing issues(mainly high bearing temperature)preventing reliable operation of turbomachinery will be addressed.Atheoretical review of radial and thrust bearing performance will be included for a basic understanding on how to handle the bearing issues.Some theoretical plots will be presented to demonstrate the effect of key bearing design parameters on bearing performance.Advanced bearing materials beyond babbitt will also be introduced as bearing upgrade options to overcome bearing issues.Case studies on radial and thrust bearing upgrades to mitigate or eliminate the bearing issues will be shared.Some of the common vibration problems preventing reliable operation of turbomachinery will also be described with suggestions on how to eliminate or mitigate the problems via changes to bearing design features or new bearing technology.A couple of case studies representing each vibration problem will be presented.展开更多
In hydrodynamic bearings traditional bearing alloys:Babbitts and bronzes are most frequently utilized.Polymer sliding layers are sometimes applied as a valuable alternative.Hard diamond-like carbon(DLC)coatings,which ...In hydrodynamic bearings traditional bearing alloys:Babbitts and bronzes are most frequently utilized.Polymer sliding layers are sometimes applied as a valuable alternative.Hard diamond-like carbon(DLC)coatings,which are also considered for certain applications may show some advantages,as well.Although material selection is of secondary importance in a full film lubrication regime it becomes important in mixed friction conditions,which is crucial for bearings with frequent starts and stops.Experimental research aimed at studying the performance of fluid film bearings in the specific operating regime,including the transition to mixed friction,is described in the paper.The tests were carried out on four tilting pad bearings of different material compositions:Steel/bronze,DLC/steel,steel/polyether ether ketone(PEEK),and steel/Babbitt.The tests comprised stopping under load and reproduction of the Stribeck curve by decreasing rotational speed to very low values,and observing the changes of friction force during the transition to mixed friction regime.Analysis of the transition conditions and other results showed clear differences between the tested bearings,illustrating the feasibility of less popular material compositions for bearings operating in specific conditions.More specifically,the DLC/steel bearing was demonstrating superior performance,i.e.lower friction,transition to mixed friction occurring at higher load,and more stable performance at start-stop regime over the other tested bearings.展开更多
The effects of surface roughness characteristics on the fluid load capacity of tilt pad thrust bearings with water lubrication were studied by the average flow model.The flow factors utilized in the average flow model...The effects of surface roughness characteristics on the fluid load capacity of tilt pad thrust bearings with water lubrication were studied by the average flow model.The flow factors utilized in the average flow model were simulated with various surface roughness parameters including skewness,kurtosis and the roughness directional pattern.The results indicated that the fluid load capacity was not only affected by the RMS roughness but also by the surface roughness characteristics.The fluid load capacity was dramatically affected by the roughness directional pattern.The skewness had a lower effect than the roughness directional pattern.The kurtosis had no notable effect on the fluid load capacity.It was possible for the fluid load capacity of the tilt pad thrust bearings to be improved by the skewness and roughness direction pattern control.展开更多
文摘In the paper, a solution of one dimensional fore region pressure build up is put forward. The performance of spring supported thrust bearing is carried out with 3 dimensional thermo elasto hydrodynamic (TEHD) lubrication theory inclusive of inlet pressure build up, thermal elastic distortion of pad and thermal effect. The effects of fore region pressure build up and the variation of some operating conditions on the performance of the pad are studied.
基金Supported by the Natural Science Foundation of China under Grant No.50675162the Program of Introducing Talents of Discipline to Universities under Grant No.B08031the Key Project of Hubei Province Science & Technology Fund under Grant No.2008CAD027
文摘Thrust bearing is a key component of the propulsion system of a ship. It transfers the propulsive forces from the propeller to the ship＇s hull, allowing the propeller to push the ship ahead. The performance of a thrust bearing pad is critical. When the thrust bearing becomes damaged, it can cause the ship to lose power and can also affect its operational safety. For this paper, the distribution of the pressure field of a thrust pad was calculated with numerical method, applying Reynolds equation. Thrust bearing properties for loads were analyzed, given variations in outlet thickness of the pad and variations between the load and the slope of the pad. It was noticed that the distribution of pressure was uneven. As a result, increases of both the outlet thickness and the slope coefficient of the pad were able to improve load beating capability.
文摘Common fluid film bearing issues(mainly high bearing temperature)preventing reliable operation of turbomachinery will be addressed.Atheoretical review of radial and thrust bearing performance will be included for a basic understanding on how to handle the bearing issues.Some theoretical plots will be presented to demonstrate the effect of key bearing design parameters on bearing performance.Advanced bearing materials beyond babbitt will also be introduced as bearing upgrade options to overcome bearing issues.Case studies on radial and thrust bearing upgrades to mitigate or eliminate the bearing issues will be shared.Some of the common vibration problems preventing reliable operation of turbomachinery will also be described with suggestions on how to eliminate or mitigate the problems via changes to bearing design features or new bearing technology.A couple of case studies representing each vibration problem will be presented.
文摘In hydrodynamic bearings traditional bearing alloys:Babbitts and bronzes are most frequently utilized.Polymer sliding layers are sometimes applied as a valuable alternative.Hard diamond-like carbon(DLC)coatings,which are also considered for certain applications may show some advantages,as well.Although material selection is of secondary importance in a full film lubrication regime it becomes important in mixed friction conditions,which is crucial for bearings with frequent starts and stops.Experimental research aimed at studying the performance of fluid film bearings in the specific operating regime,including the transition to mixed friction,is described in the paper.The tests were carried out on four tilting pad bearings of different material compositions:Steel/bronze,DLC/steel,steel/polyether ether ketone(PEEK),and steel/Babbitt.The tests comprised stopping under load and reproduction of the Stribeck curve by decreasing rotational speed to very low values,and observing the changes of friction force during the transition to mixed friction regime.Analysis of the transition conditions and other results showed clear differences between the tested bearings,illustrating the feasibility of less popular material compositions for bearings operating in specific conditions.More specifically,the DLC/steel bearing was demonstrating superior performance,i.e.lower friction,transition to mixed friction occurring at higher load,and more stable performance at start-stop regime over the other tested bearings.
基金the National Basic Research Program of China (973)，the National Natural Science Foundation of China
文摘The effects of surface roughness characteristics on the fluid load capacity of tilt pad thrust bearings with water lubrication were studied by the average flow model.The flow factors utilized in the average flow model were simulated with various surface roughness parameters including skewness,kurtosis and the roughness directional pattern.The results indicated that the fluid load capacity was not only affected by the RMS roughness but also by the surface roughness characteristics.The fluid load capacity was dramatically affected by the roughness directional pattern.The skewness had a lower effect than the roughness directional pattern.The kurtosis had no notable effect on the fluid load capacity.It was possible for the fluid load capacity of the tilt pad thrust bearings to be improved by the skewness and roughness direction pattern control.
