This study explores the effects of wear and shaft-shape error defects on the tribo-dynamic responses of water-lubricated bearings under nonlinear propeller disturbance using a numerical model. The model proposed in this paper is verified by comparing the results from experiments and simulations in published studies. Numerical simulation studies reveal the effects of nonlinear propeller disturbance on the dynamic behavior and lubrication performance, such as hydrodynamic force, contact force, and journal trajectory, of the water-lubricated bearings with wear and shaft-shape errors. In addition, the effects of the critical factors for wear and shaft-shape errors, including wear depth, deviation angle, magnitude, and waviness order, on the tribo-dynamic responses of water-lubricated bearings are identified. The results of numerical spectrum analyses show that the nonlinear disturbance significantly affects the dynamic behavior (shown as the fluctuation range of the journal trajectory increases), and reasonable wear parameters can improve the lubrication performance of the water-lubricated bearing. Moreover, the effects of shaft-shape errors on the transient hydrodynamic force, contact force, film thickness, pressure, and journal trajectory are greater than that of wear.

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Purpose The purpose of this paper is to verify the effectiveness of the proposed transient mixed lubrication and wear coupling model [mixed lubrication and wear (MLW) coupling model] under water lubricated conditions by comparing with the experimental results. Design/methodology/approach Water lubricated bearings are the key parts of the transmission system of an underwater vehicle and some surface ships. In this study, the friction and wear behaviors of rubber, nylon and polyether ether ketone (PEEK) samples with stainless steel underwater lubrication were compared by using ring-block contact structure on multifunctional friction and wear test bench-5000 friction and wear tester. Findings The results show that the transient wear depth and wear amount of PEEK, nylon and rubber samples under water lubrication are in good agreement with the calculated results of the theoretical model, which verifies the rationality and scientific nature of the MLW coupling model. Thus, the numerical model is applicable for the wear prediction of the journal bearing under water-lubricated conditions. Furthermore, numerical and experimental results reveal that the anti-wear performance among three water-lubricated materials can be ranked by: PEEK > nylon > rubber. Originality/value It is expected that this study can provide more information for experimental and numerical research of water-lubricated bearings under water-lubricated conditions.

The purpose of this study is to assess the role of the turbulence on the lubrication performances of coupled journal-thrust water-lubricated bearing with micro grooves using a numerical model. The results of the simulation model are compared to the published experimental data to verify the validity of the numerical model. The load capacity, maximum film pressure and local Reynolds number variations with the rotating speed, eccentricity, radial clearance, axial geometric gap and micro groove depth for coupled journal-thrust water-lubricated bearing are examined. Furthermore, the calculated results under the turbulent flow are compared with those under laminar flow for coupled and separate bearings. The results show that the turbulence effect can improve the lubrication performances by enlarging fluid pressure and load capacity of the coupled journal-thrust bearing and the laminar flow assumption is no longer applicable to the actual operating conditions of the water-lubricated bearings at a high rotation speed. In addition, there are existed optimal micro groove depths for both journal bearing and thrust bearing to reach the peak of the load capacity while the optimal micro groove depths for journal bearing and thrust bearing are not the same.