Computational evaluation of dynamic coefficients of thrust bearings; effect of artificial texturing on thermohydrodynamic performance

This paper presents the exploration for improving the static and dynamic performance behaviours of a self-acting rigid gas journal bearing employing some new conceived micro-depth pocketed surface topographies at the bore. The conceived micro-pockets comprise of relatively large size rectangular pocket having micro-depth at bearing bore in the converging zone followed by placing of different designs of sub-pockets at the trailing edge of the previous one in the direction of journal rotation. The form of equation achieved from Patir and Cheng’s model for the case of hydrodynamic lubrication regime and the related dynamic pressure equations have been solved using the finite volume method discretisation scheme followed by the solution of the algebraic equations using the Gauss-Seidel iterative method. The minimum film thickness, frictional force, side leakage, bearing dynamic coefficients, effective stiffness, effective damping, and critical mass parameters have been investigated with each new bore surface topography and compared with the performances of conventional aerodynamic journal bearing. Substantial improvements in both static and dynamic performances have been found with the new micro-pocketed bore surface topographies as compared to conventional one. Moreover, the established best bore design has produced significant increase (21%) in minimum film thickness, substantial reduction (12%) in coefficient of friction, and excellent improvement (170%) in the stability parameter (critical mass) as compared to the conventional case.

Section: Governing Equations For Dynamic Performancesmentioning

confidence: 99%

Effects of new micro-pocketed bore surface topographies on the performance behaviours of aerodynamic journal bearing

Pattnayak¹,

Pandey²,

Dutt³

2021

“…Therefore, the improvement of lubrication performance and the reduction of wear are the key problem required to be solved urgently for water lubricated bearings. Surface texturing is an effective method to improve tribological performances of contacting surface, which has been widely used in many mechanical components [3][4][5][6][7]. Experimental studies reveal that the reasonable distribution and geometric parameters of texture are capable for enhancing the load capacity, yielding larger hydrodynamic pressure, reducing coefficient of friction(COF) and wear rate [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

A simulation model to comparative analysis the effect of texture bottom shape on wear and lubrication performances for micro-groove water lubricated bearings

Jin¹,

Xiao²,

Xiang³

et al. 2021

The novelty of this paper is to explore the role of the texture bottom shape on the transient wear performance under mixed lubrication condition using a numerical model. In the numerical model, the transient interaction between the effects of wear and mixed lubrication are analyzed by incorporating the wear depth distribution into the equation of lubrication gap in each time step. A validating experiment is performed to demonstrate the effectiveness of the numerical model. The wear and lubrication performances of bearings with five bottom shapes, i.e., semi ellipse, rectangle, isosceles triangle, left triangle and right triangle, are evaluated comparatively. Additionally, the effects of operating time, operating conditions (linear speed and external load) and some input parameters on tribological performances at different bottom shapes are discussed. The simulation results reveal that the texture bottom shape has significant effect on transient wear performance, thereinto, the groove with left triangle bottom shape obtain optimal transient wear and lubrication performances compared with the other four bottom shapes. The frictional behaviors of water lubricated bearing’s contacting surface would be improved by optimizing the texture’s internal structural shape especially under severe wear operating condition.

“…In recent years, numerous studies have shown that non-smooth surfaces have great potential in improving the lubrication and wear resistance of friction pairs [18][19][20]. Specifically, the main functions of surface textures/topographies can be classified into several types according to different lubrication states: (1) under mixed to dry friction, acting as traps to capture wear debris and reducing resistance and adhesion [21]; (2) under mixed to boundary lubrication, providing micro-reservoirs and resulting in numerous micro-fluid film bearings to enhance lubrication of friction pairs [22]; (3) under hydrodynamic lubrication, generating hydrodynamic pressure to increase the load-carrying capacity [23,24]. Among them, the main function mechanism of surface texture/topography under hydrodynamic lubrication can be explained as follows: In hydrodynamic lubrication, positive pressure will be generated when fluid flows along a convergent gap, but not along a divergent gap.…”

Section: Introductionmentioning

confidence: 99%

“…(2) under mixed to boundary lubrication, providing micro-reservoirs and resulting in numerous microfluid film bearings to enhance lubrication of friction pairs [22]; (3) under hydrodynamic lubrication, generating hydrodynamic pressure to increase the loadcarrying capacity [23,24]. Among them, the main function mechanism of surface texture/topography under hydrodynamic lubrication can be explained as follows: In hydrodynamic lubrication, positive pressure will be generated when fluid flows along a convergent gap, but not along a divergent gap.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on sealing performance of non-contact finger seal with herringbone groove surface topography

Chen¹,

Zhang²,

Cui³

et al. 2021

Since the last decade, the non-contact finger seal (NCFS) has attracted an increasing number of researchers due to its inherent flexibility and non-contact features, which can significantly improve the service life and reduce the leakage rate of the finger seals. In this paper, to enhance the NCFS sealing performance, lifting pads with twenty (20) different herringbone groove surface topographies are proposed based on the uniform design method. Numerical analysis is carried out based on the two-way fluid-structure interaction (FSI) method to better mimic the actual working conditions. The analysis of results using statistical tools reveals that the herringbone groove topographies placed on the bottom surface of low-pressure lifting pads can significantly improve the load-carrying capacity and sealing performance. In addition, the correlation analysis of the sealing performance and geometric parameters of the herringbone groove demonstrate that reducing the groove width or increasing the groove internal angle can improve the lifting and leakage capacities. Finally, the optimal herringbone groove and general structure (no groove) are comparatively analysed under variable working conditions, and the results show that the former has much better sealing performance.