scholarly journals Propeller Excitation of Longitudinal Vibration Characteristics of Marine Propulsion Shafting System

2014 ◽  
Vol 2014 ◽  
pp. 1-19 ◽  
Author(s):  
Ganbo Zhang ◽  
Yao Zhao ◽  
Tianyun Li ◽  
Xiang Zhu
Keyword(s):  
Natural Frequency ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Longitudinal Vibration ◽  
Axial Stiffness ◽  
Oil Film ◽  
Marine Propulsion ◽  
Hydrodynamic Lubrication Theory ◽  
Small Perturbation Method ◽  
Thrust Load

The submarine experiences longitudinal vibration in the propulsion shafting system throughout most of run. A transfer matrix model of the propulsion shafting system, in which the dynamic characteristics of oil film within thrust bearing are considered, is established to describe the dynamic behavior. Using hydrodynamic lubrication theory and small perturbation method, the axial stiffness and damping of oil film are deduced in great detail, followed by numerical estimation of the foundation stiffness with finite element method. Based upon these values of dynamic parameters, the Campbell diagram describing natural frequencies in terms of shafting rotating speeds is available, and the effect on the 1st natural frequency of considerable variations in thrust bearing stiffness is next investigated. The results indicate that the amplitude of variation of the 1st natural frequency in range of low rotating speeds is great. To reduce off-resonance response without drastic changes in propulsion shafting system architecture, the measure of moving thrust bearing backward is examined. The longitudinal vibration transmission through propulsion shafting system results in subsequent axial excitation of hull; the thrust load acting on hull is particularly concerned. It is observed that the measures of structural modification are of little benefit to minimize thrust load transmitted to hull.

The Influence of Gear Parameters on Oil Film Thickness of Tooth Surface

2011 ◽  
Vol 79 ◽  
pp. 293-297
Author(s):  
Li Hong Liu ◽  
Zhan Ni Li ◽  
Han Bing Cao
Keyword(s):  
Film Thickness ◽  
Hydrodynamic Lubrication ◽  
Gear Ratio ◽  
Tooth Surface ◽  
Speed Ratio ◽  
Oil Film ◽  
Single Tooth ◽  
Hydrodynamic Lubrication Theory ◽  
Tooth Flank ◽  
Center Distance

Applying elastic-hydrodynamic lubrication theory, oil film thickness of tooth surface was studies in accordance with the quasi-steady state. This paper focused on the influence of gear parameters such as gear ratio, module and center distance on the thickness of oil film of tooth flank. The results show, as speed ratio increases, oil film thickness increases significantly. When the number of teeth is fixed, oil film thickness increases significantly with the increase of module. When center distance is fixed, oil film thickness declines greatly with the increase of module in both into meshing and out of meshing points. Therefore when center distance is fixed, less module and more teeth are selected，on the condition that gear intensity is met. By results analyzing, the minimal oil film thickness may occur in the single tooth meshing area and into meshing or out of meshing points.

Modeling and Analysis of High-Speed Journal Bearing Based on Thermal Hydrodynamic Lubrication Theory

2013 ◽  
Vol 380-384 ◽  
pp. 82-86 ◽  
Author(s):  
Song Sheng Li ◽  
Yu Xin Lu ◽  
Ma Li Dong ◽  
Juan Shao ◽  
Feng Yu
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Hydrodynamic Lubrication ◽  
Lubrication Theory ◽  
Engineering Practice ◽  
Isothermal Model ◽  
Modeling And Analysis ◽  
Oil Film ◽  
Rotating Speed ◽  
Hydrodynamic Lubrication Theory

Journal bearing in high-speed working conditions will generate a lot of heat, which affects its working performance. Based on hydrodynamic lubrication theory, a model of the thermal hydrodynamic lubrication was built, and the distributions of temperatures and pressures of the oil film were obtained from the simultaneous solution of generalized Reynolds, energy and viscosity-temperature equations. The results show that the temperature will increase and the pressure decrease of the lubrication oil film with the rising of the rotating speed, which will make the the bearing capacity decrease. Compared with the traditional isothermal model, the thermal hydrodynamic lubrication model is more consistent with the engineering practice.

scholarly journals Dynamic analysis of double-helical gear system considering effect of oil film among meshing teeth

2020 ◽  
Vol 12 (5) ◽  
pp. 168781402092011
Author(s):  
Minghu Yin ◽  
Yahui Cui ◽  
Xiangjun Meng ◽  
Jinzhong Zuo ◽  
Yuhao Qi
Keyword(s):  
Dynamic Analysis ◽  
High Speed ◽  
Dynamic Models ◽  
Hydrodynamic Lubrication ◽  
Helical Gear ◽  
Gear System ◽  
Heavy Load ◽  
Oil Film ◽  
Hydrodynamic Lubrication Theory ◽  
Meshing Characteristics

The oil film among meshing teeth is just like a spring-damping element, and it can dominate the friction and meshing characteristics of the gear pair and influence its dynamic performances further. Thus, this article focuses on a double-helical gear system and makes efforts to consider the effect of the oil film among meshing teeth more deeply, which can enhance the precision of dynamic analysis for the gear system. First, based on the elasto-hydrodynamic lubrication theory and “microtomy” method, the models of friction and meshing characteristics are developed including the friction state and spring-damping effect of the oil film among meshing teeth; then, the dynamic models of the double-helical gear system with the effect of the oil film among meshing teeth are established, and finally, the experiments are carried out to verify the value of the models developed in this article. According to the theoretical and experimental analyses, it can be seen that the dynamic model considering the effect of the oil film among the meshing teeth is more precise and practical, and the effect of the oil film should be considered in the dynamic analysis of the gear system, especially at the condition with heavy load or high speed.

Characteristics Analysis of Angular Contact Ball Bearing Based on the Oil Film Stiffness1

2011 ◽  
Vol 480-481 ◽  
pp. 599-604
Author(s):  
Zhi Feng Liu ◽  
Hao Zhou ◽  
Yong Sheng Zhao
Keyword(s):  
Ball Bearing ◽  
Hydrodynamic Lubrication ◽  
Rolling Bearing ◽  
Angular Contact Ball Bearing ◽  
Oil Film ◽  
Stiffness Model ◽  
Characteristics Analysis ◽  
Bearing Stiffness ◽  
Hydrodynamic Lubrication Theory ◽  
Film Stiffness

The bearing stiffness model is established based on the Hertz contact theory and the hydrodynamic lubrication theory of rolling bearing in this paper, the dynamic characteristics of the angular contact ball bearing and the relationship between the bearing preload, the speed and the stiffness of the angular contact ball bearing is analyzed, as well as the influence of the oil film stiffness on the bearing total stiffness. The results from taking 71924ACD/P4A bearing as an example shows that the preload and the speed have important effect on the stiffness of bearing. By the contrast of two kinds of situations, a conclusion can be drawn that when considering the oil film stiffness,the total stiffness reduces 0-40% than not considering the oil film stiffness.

Design of Main Pump Motor’s Water Lubricated Bearing and Research on its Lubrication Performances

2012 ◽  
Vol 538-541 ◽  
pp. 1971-1974
Author(s):  
Xin Rong Wang ◽  
Xiao Hai Li ◽  
Ya Chao Cui ◽  
Li Hua Yang
Keyword(s):  
Carrying Capacity ◽  
Thrust Bearing ◽  
Working Condition ◽  
Hydrodynamic Lubrication ◽  
Thrust Bearings ◽  
Structure Of Water ◽  
Low Viscosity ◽  
Factors Influencing ◽  
Hydrodynamic Lubrication Theory ◽  
The Right

Water-lubricated thrust bearing is a key component of certain main pump motor. In this paper, the right structure of water-lubricated thrust graphite bearings is designed based on low viscosity hydrodynamic lubrication theory by combining the bearings running working condition, and the frictional accessory material is also determined by theoretical analysis and test. The factors influencing lubrication performances of water-lubricated thrust bearings are analyzed; the methods improving lubrication performances are put forward to guarantee that water-lubricated thrust graphite bearings have the good lubrication performances, good carrying capacity and longer work life.

Performance of Centrally Pivoted Sector Thrust-Bearing Pads—Sea Trials Aboard USS Barry (DD 933)

1964 ◽  
Vol 86 (3) ◽  
pp. 483-496 ◽  
Author(s):  
R. C. Elwell ◽  
R. E. Gustafson ◽  
J. C. Reid
Keyword(s):  
Film Thickness ◽  
Simultaneous Measurement ◽  
Thrust Bearing ◽  
Full Range ◽  
Hydrodynamic Type ◽  
Oil Film ◽  
Thrust Bearings ◽  
The Third ◽  
Marine Propulsion ◽  
Rough Water

This paper is the third in a series which presents the results of a study of main marine propulsion bearings of the conventional pivoted-pad, hydrodynamic type. It presents a description of tests conducted at sea on the main propulsion thrust bearings of the destroyer USS Barry (DD 933). Steady steaming tests in both calm and rough water are reported, for the full range of design speeds and loads. Data taken in these tests are compared to the values predicted by the analytical results of the first two papers in this series. These earlier papers analyzed the performance of such bearings under conditions of constant speed and load. Data from simultaneous measurement of 59 temperatures and 18 oil-film thickness gages is presented.

Mode Coupling in Torsional and Longitudinal Shafting Vibrations

1983 ◽  
Vol 20 (03) ◽  
pp. 257-271
Author(s):  
Michael G. Parsons
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Longitudinal Vibration ◽  
Added Mass ◽  
Mode Shapes ◽  
Regression Equations ◽  
Vibration Problem ◽  
Vibratory Response ◽  
Marine Propulsion ◽  
Coupling Characteristics

The effect of propeller coupling on the torsional and longitudinal vibration of marine propulsion shafting is studied. Recent research on the nature and computation of propeller added mass and damping is reviewed. It is now possible to estimate the inertia coupling and velocity coupling characteristics which couple the torsional and longitudinal vibration of a marine propeller. Regression equations suitable for estimating the torsional and longitudinal added mass and damping of 4-, 5-, 6-, and 7-bladed Wageningen B-Series propellers are presented in the Appendix. The torsional and longitudinal modeling of a typical marine propulsion plant is reviewed. The numerical techniques and computer programs used in solving the free vibration problem for natural frequencies and mode shapes and the forced vibration problem for vibratory response are introduced. Results for a realistic numerical example are presented to compare the natural frequencies, mode shapes, and vibratory response which are obtained when the propeller coupling is neglected with those obtained with the propeller coupling included. In general, the natural frequencies are shown to change by less than 2 percent. The modes shapes can show significant change. Vibratory response can be either increased or decreased. Some cases show that neglecting the propeller coupling can result in more than a 50 percent underprediction of the vibratory response. The coupling effects are greatest when a torsional natural frequency obtained with the propeller coupling neglected and a longitudinal natural frequency obtained with the propeller coupling neglected converge.

Evaluation standard and improvement method for multi-column envelope profile in single screw compressors

2020 ◽  
Vol 234 (6) ◽  
pp. 900-916
Author(s):  
Rui Huang ◽  
Guoqing Chen ◽  
Ting Li ◽  
Quanke Feng
Keyword(s):  
Hydrodynamic Lubrication ◽  
Optimization Method ◽  
Calculation Model ◽  
Test Results ◽  
Evaluation Standard ◽  
Oil Film ◽  
Single Screw ◽  
Improvement Method ◽  
Hydrodynamic Lubrication Theory ◽  
Total Oil

Multi-column envelope profile is the newly proposed engagement pair’s profile for single screw compressors. Based on hydrodynamic lubrication theory, a calculation model of the oil film moments for star wheel teeth with multi-column envelope profile was established. In order to balance the total oil film moments of the teeth, a profile evaluation standard and improvement method for the multi-column envelope profile were proposed. Then, the profile for a single screw compressor was optimized. The meshing pair with optimized profile is loaded into a prototype to carry out the running test. Results show that the optimization method improves the wear resistance of the star wheel teeth, especially the teeth’s front side, and enhances the running stability of the compressor.

Comparison with Thermo Hydrodynamic Lubrication between 2D and 3D Model in Thrust Bearing by Computing Simulation

2010 ◽  
Vol 129-131 ◽  
pp. 1336-1340
Author(s):  
Zhi Lan Chen ◽  
Jun Zhu
Keyword(s):  
3D Model ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Three Dimensional ◽  
Axial Direction ◽  
Maximum Temperature ◽  
Interface Problem ◽  
Oil Film ◽  
Lubrication Performance ◽  
Calculated Model

As the interface problem of discontinuity boundary condition between the oil film and the pad in thrust bearing, a conjugated solution method by using the temperature continuity and the heat flux continue is proposed. The three-dimensional calculated model of thrust bearing is constructed and solved by using finite difference method. Comparing with 2D model, the characteristics of the lubrication performance of 3D model are more different. The results show that the three-dimensional calculated model not only revealed the relation of temperature variation between the oil film layer and the pad in axial direction, but also exactly reflected real temperature distribution in the pad surface. In the same oil feed temperature condition, the minimum film thickness is 63.8μm and the maximum temperature on the pad surface reached 55°C for 3D mode, 72.6μm and 60°C for 2D mode.

On the Thrust Bearing Characteristics in Turbulent Flow

1981 ◽  
Vol 103 (3) ◽  
pp. 453-458 ◽  
Author(s):  
K. Venkateswarlu ◽  
Cz. M. Rodkiewicz
Keyword(s):  
Theoretical Analysis ◽  
Turbulent Flow ◽  
Numerical Method ◽  
Eddy Viscosity ◽  
Thrust Bearing ◽  
Hydrodynamic Lubrication ◽  
Governing Equations ◽  
Eddy Viscosity Model ◽  
Hydrodynamic Lubrication Theory ◽  
Made In

A theoretical analysis was made of the effects of the inclusion of inertia, viscous, and turbulence terms in hydrodynamic lubrication theory is applied to a thrust bearing. The solution to the governing equations is obtained by an iterative numerical method. An improved eddy viscosity model is employed to evaluate the turbulence term. Results are compared with existing measurements made in bearing models and also with other theoretical solutions. The contribution of inertia and viscous terms is discussed in light of the obtained results.

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