Improvement of Operating Characteristics of High-Speed Hydrodynamic Journal Bearings by Optimum Design: Part I— Formulation of Methodology and Its Application to Elliptical Bearing Design

2000 ◽  
Vol 123 (2) ◽  
pp. 305-312 ◽  
Author(s):  
H. Hashimoto ◽  
K. Matsumoto
Keyword(s):  
Optimum Design ◽  
High Speed ◽  
Optimization Technique ◽  
Orientation Angle ◽  
Journal Bearings ◽  
Graphical Form ◽  
Operating Characteristics ◽  
Design Variables ◽  
Wide Range ◽  
Bearing Design

This paper describes the optimum design methodology for improving operating characteristics of hydrodynamic journal bearings and its application to elliptical journal bearing design used in high-speed rotating machinery. The hybrid optimization technique combining the direct search method and the successive quadratic programming is applied effectively to find the optimum solutions. In the optimum design of elliptical journal bearings, the design variables such as vertical and horizontal radial clearances, bearing length-to-diameter ratio and bearing orientation angle are determined to minimize the objective function defined by the weighted sum of maximum averaged oil film temperature rise, leakage flow rate, and the inversion of whirl onset speed of the journal under many constraints. The results obtained are shown in graphical form for a wide range of journal rotational speed. Comparing the optimized operating characteristics with the characteristics calculated from the random selected design variables, the effectiveness of optimum design is clarified.

Improvement of the Static and Dynamic Characteristics of Magnetic Head Sliders by Optimum Design

1999 ◽  
Vol 122 (1) ◽  
pp. 280-287 ◽  
Author(s):  
Hiromu Hashimoto ◽  
Yasuhisa Hattori
Keyword(s):  
Objective Function ◽  
Optimum Design ◽  
Amplitude Ratio ◽  
Optimization Technique ◽  
Hard Disk Drives ◽  
Maximum Amplitude ◽  
Disk Surface ◽  
Operating Conditions ◽  
Magnetic Head ◽  
Design Variables

The aim of this paper is to develop a general methodology for the optimum design of magnetic head sliders in improving the spacing characteristics between a slider and disk surface under static and dynamic operating conditions of hard disk drives and to present an application of the methodology to the IBM 3380-type slider design. To generate the optimal design variables, the objective function is defined as the weighted sum of the minimum spacing, the maximum difference in the spacing due to variation of the radial location of the head, and the maximum amplitude ratio of the slider motion. Slider rail width, taper length, taper angle, suspension position, and preload are selected as the design variables. Before the optimization of the head, the effects of these five design variables on the objective function are examined by a parametric study, and then the optimum design variables are determined by applying the hybrid optimization technique, combining the direct search method and successive quadratic programming. From the obtained results, the effectiveness of optimum design on the spacing characteristics of magnetic heads is clarified. [S0742-4787(00)03701-2]

Effect of Journal Misalignment on the Oil Film Pressure and Temperature Distribution of 3-Lobe Offset Journal Bearing

2005 ◽  
Author(s):  
S. Strzelecki ◽  
Z. Towarek
Keyword(s):  
Temperature Distribution ◽  
High Speed ◽  
Journal Bearing ◽  
Journal Bearings ◽  
Good Stability ◽  
Rotating Machines ◽  
Film Pressure ◽  
Bearing Design ◽  
Journal Misalignment ◽  
Oil Film Pressure

The design of turbines and compressors operating at the high rotational speeds applies the 3-lobe journal bearings. In many cases the classic 3-lobe journal bearings supporting the rotors, are showing the problem of rotor stability. This problem can be avoided by the application of 3-lobe Offset bearings. This type of bearing fulfils the conditions of reliable bearing design and good stability in the case of high speed rotating machines.

Reliability-based optimum design for mechanical problems using genetic algorithms

2008 ◽  
Vol 222 (9) ◽  
pp. 1791-1799 ◽  
Author(s):  
Y-T Tsai ◽  
H-C Chang
Keyword(s):  
Genetic Algorithms ◽  
Optimum Design ◽  
Optimization Technique ◽  
Structural Complexity ◽  
Optimal Solution ◽  
Unconstrained Minimization ◽  
Reliability Design ◽  
Performance Indexes ◽  
Design Variables ◽  
Relationship Of

A reliability oriented design approach for mechanical or structural components is implemented primarily based on strength—stress interference (SSI) theory. This paper demonstrates a principle for combining SSI theory and an optimization technique for developing a reliability-based optimum design for mechanical problems. The independently paired information (strength and stress distributions) are basic while progressing reliability design. For a complex system, the independently paired information sometimes is not easily clarified due to the structural complexity or the coupled relationship of the loads. To treat these problems, the paper proposes to express the independently paired information from the viewpoint of supply-requirement of a design in performance. The supply (provided by a design) is analogized to the strength as well as the requirement (requested by the customer) to the stress. Based on the viewpoint of supply-requirement, the paper presents four types of performance-related reliability measurement to fulfil reliability design for mechanical problems. The reliability measurements are derived according to the related design variables that formulate the performance indexes. Next, the designed problem expressed with probabilistic formulation is transformed into an unconstrained minimization problem subjected to the constraints of the performance needs and its reliability target. Genetic algorithms (GAs) are used to find the optimal solution for the reliability design problem. The related theories and an example of design are reported in this paper to depict the proposed method.

scholarly journals An Instrumented High-Speed Rotor With Embedded Telemetry for the Continuous Spatial Pressure Profile Measurement in Gas Lubricated Bearings: A Proof of Concept

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Karim Shalash ◽  
Jürg Schiffmann
Keyword(s):  
System Identification ◽  
High Speed ◽  
Pressure Field ◽  
Pressure Profile ◽  
Journal Bearings ◽  
Profile Measurement ◽  
Pressure Measurements ◽  
Wide Range ◽  
Static Conditions

Abstract Pressure is the constitutive quantity governing the flow field in gas lubricated bearings. Knowledge of the pressure is of principal importance in the fundamental understanding of such bearings as well as for the validation of their models. Pressure measurements can be done from the bearing side using pressure taps, yet, several details will not be captured. In order to acquire a continuous scan of the pressure field inside the bearing, it is necessary to measure from the rotor side. This paper presents an instrumented measurement high-speed rotor with embedded pressure probes and a wireless telemetry that is capable of the continuous pressure field measurement within the gas film of journal bearings. The rotor was tested on externally pressurized gas journal bearings (EPGJBs) (D = 40 mm and L/D = 1), and pressure profile measurements were acquired up to 37.5 krpm (DN 1.5 M). Measurements at discrete points using pressure taps inside the test bearing were also performed for comparison. The measurements from both sides (bearing and rotor) were in good agreement at quasi-static conditions. At higher operational speeds, it was necessary to perform an in situ system identification and calibration for the embedded pressure probes using the bearing side measurements as a reference. The in situ system identification technique was successful to reconstruct the attenuated pressure signals for a wide range of supply pressures (amplitudes) and rotor speeds (excitation frequencies). The instrumented rotor was proven qualified to perform time-resolved pressure measurements within the gas film of journal bearings up to 37.5 krpm.

A Tribological Study of Partial-Arc Bearings With Egg-Shaped Surface Texture for Microturbine Applications

2012 ◽  
Author(s):  
D. A. Bompos ◽  
P. G. Nikolakopoulos ◽  
C. I. Papadopoulos ◽  
L. Kaiktsis
Keyword(s):  
Friction Coefficient ◽  
High Speed ◽  
Stokes Equations ◽  
Slenderness Ratio ◽  
Substantial Improvement ◽  
Journal Bearings ◽  
Navier Stokes ◽  
Small Scale ◽  
Tribological Study ◽  
Wide Range

Recent research has demonstrated that proper use of texture geometries can improve the performance of journal and thrust bearings. In particular, for journal bearings, elliptical and egg-shaped texture patterns appear as promising candidates for improving bearing performance, in terms of load carrying capacity and friction coefficient. The expected advantages should also hold for partial-arc bearings, which, for small scale – high speed applications, are characterized by significant advantages, in comparison to full bearings. In the present paper, a tribological study of partial-arc journal bearings with periodic egg-shaped texture applied on the stator surface is presented. Computational Fluid Dynamics (CFD) simulations are performed and processed to yield the bearing performance indices. Here, the bearing geometry and the texture characteristics are defined parametrically; a wide range of bearing designs is thus accounted for. Flow simulations are based on the numerical solution of the Navier-Stokes equations for incompressible isothermal flow. The effects of dimple shape, bearing eccentricity, bearing arc angle, and slenderness ratio on the bearing performance are investigated. The present results demonstrate that a substantial improvement of journal bearing performance, especially in terms of the friction coefficient, in comparison to that of smooth bearings, is feasible.

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