A direct numerical approach to compute the nonlinear rotordynamic coefficient of the noncircular gas journal bearing

Yadav, Saurabh; Rajput, Arvind K.; Ram, Nathi; Sharma, Satish C.

doi:10.1177/1350650117719602

Cited by 9 publications

(6 citation statements)

References 30 publications

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“…The fluid film thickness of a two-lobe bearing is calculated by using following expression 17,24 where x¯l,z¯l are the coordinate of the lobe centre and θl k is the lobe angle.…”

Section: Discussionmentioning

confidence: 99%

Stability analysis of a rigid rotor supported by two-lobe hydrodynamic journal bearings operating with a non-Newtonian lubricant

Yadav

Rajput

Ram

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part J:

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In the present work, an investigation has been performed on a rigid rotor supported by two-lobe journal bearings operating with a non-Newtonian lubricant. The governing Reynolds equation for pressure field is solved by using non-linear finite element method. Further to study the dynamic stability of the bearing system, governing equation of motion for the rotor position is solved by fourth order Runge–Kutta method. Bifurcation and Poincaré maps of two-lobe bearings are presented for different values of the non-Newtonian parameter and bearing ellipticity ratio. The numerical results illustrate that the ellipticity of a bearing with a dilatant lubricant improve the stability of the rotordynamic system.

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“…The fluid film thickness of a two-lobe bearing is calculated by using following expression 17,24 where x¯l,z¯l are the coordinate of the lobe centre and θl k is the lobe angle.…”

Section: Discussionmentioning

confidence: 99%

Stability analysis of a rigid rotor supported by two-lobe hydrodynamic journal bearings operating with a non-Newtonian lubricant

Yadav

Rajput

Ram

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part J:

Self Cite

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“…Static [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and dynamic [12,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] performances of conventional rigid bore aerodynamic journal bearings have been explored by many researchers in the past from various investigation perspectives. Thermal effects, influence of inertia force, rarefication and turbulence on the static performances have been explored and presented by the authors [4,5,11].…”

Section: Introductionmentioning

confidence: 99%

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

Pattnayak¹,

Pandey²,

Dutt³

2021

Surf. Topogr.: Metrol. Prop.

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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.

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“…Yadav et al presented a direct numerical approach to compute the nonlinear rotor dynamic coefficient of the noncircular gas bearings. 9 In this study, they used a double partial differential approach to compute the dynamic characteristics of analyzed journal bearings. Results show that the bearing ellipticity ratio significantly affects the nonlinear trajectory of the journal center.…”

Section: Introductionmentioning

confidence: 99%

Effect of texture geometry on the performance of noncircular aerodynamic journal bearings

Mehrjardi¹

2021

Proceedings of the Institution of Mechanical Engineers, Part J:

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Today, considerable uses of aerodynamic journal bearings have attracted the attention of many researchers in the field of tribology. Therefore, the theoretical and experimental analysis of their performance has been the subject of many researches. Growing application of the gas journal bearings is due to their capability in various engineering fields such as instrumentation and high-speed machines like spindles, small-scale turbomachines, and precision gyroscopes, dental milling machines, and many other rotor-bearing systems. Upgrading the performance of gas bearings by changing their geometry or using new compressible lubricants has always been one of the suggestions proposed by the tribology researchers. Recently, the development of new technologies such as laser milling and lithography increased the possibility of creating textured surfaces as a way to improve the performance of journal bearings. So, in this study, the effects of texture geometry on the steady-state performance of two-lobe noncircular aerodynamic journal bearings are presented. For this purpose, the governing Reynolds equation of hydrodynamic gas lubrication is analyzed by finite element method according to the changes of the lubricant film thickness in presence of the cubical, cylindrical, and ellipsoidal surface textures. Results show that the creation of textures on the lower lobe compared to the upper lobe or the whole surface is more effective on the performance of two-lobe aerodynamic bearings. Also, increasing both the dimple depth and the amount of bearings noncircularity, especially at shallow texture depth, cause more significant changes in the lubricant film pressure distribution and the bearing performance parameters such as load-carrying capacity, attitude angle, and frictional power loss. Further, it is obvious that the creation of cubical, cylindrical and ellipsoidal textures especially at shallow depth with an increase in the noncircularity of bearings’ geometry have a higher impact on the steady-state performance of the studied rotor-bearing system, respectively.

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A direct numerical approach to compute the nonlinear rotordynamic coefficient of the noncircular gas journal bearing

Cited by 9 publications

References 30 publications

Stability analysis of a rigid rotor supported by two-lobe hydrodynamic journal bearings operating with a non-Newtonian lubricant

Stability analysis of a rigid rotor supported by two-lobe hydrodynamic journal bearings operating with a non-Newtonian lubricant

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

Effect of texture geometry on the performance of noncircular aerodynamic journal bearings

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