Determination of the Discharge Coefficient of a Thin-Walled Orifice Used in Hydrostatic Bearings

The characteristics of hydrostatic bearings can be influenced by the compensating device they use, for example, a thin-walled orifice (diaphragm). The flow through the orifice is given by a law where an ad hoc discharge coefficient appears, and, in order to guarantee the characteristics of the hydrostatic bearing, this coefficient must be calibrated. The aim of this work is to provide an accurate estimation of the discharge coefficient under specific conditions. Therefore an experimental bench was designed and a numerical model was carried out. The results obtained then by the experimental and theoretical approach were compared with the values given by the literature. Finally, the influence of the discharge coefficient on the behavior of a thrust bearing is examined.

Download Full-text

Simulation on Multi-Oil-Cavity and Multi-Oil-Pad Hydrostatic Bearings

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.274.274 ◽

2013 ◽

Vol 274 ◽

pp. 274-277 ◽

Cited By ~ 1

Author(s):

Xiao Qiu Xu ◽

Jun Peng Shao ◽

Xiao Dong Yang ◽

Yan Qin Zhang ◽

Xiao Dong Yu ◽

...

Keyword(s):

Hydraulic System ◽

Thrust Bearing ◽

Three Dimensional ◽

Structure Design ◽

Analysis Software ◽

Hydrostatic Bearing ◽

Hydrostatic Bearings ◽

Simulation Results ◽

Three Dimensional Models ◽

Volume Method

Taking multi-oil-cavity and multi-oil-pad hydrostatic bearings as studied projects, firstly make brief instructions for structure characteristics and working principal of hydraulic system; Then, build three-dimensional models of multi-oil-cavity and multi-oil-pad hydrostatic bearings respectively. Adopting finite volume method, oil film mesh is generated by universal finite analysis software CFD; then, carry on numerical simulations for pressure distribution and temperature distribution of the two studied hydrostatic thrust bearing under various viscosity, and make comparative analysis for difference between the two studied hydrostatic thrust bearing. Based on the analysis of numerical simulation results, the conclusions whether oil-return groove is set for hydrostatic bearing could be received. Simulation results reveal truly the influence of setting oil-return groove or not on hydrostatic thrust bearing, and improve structure design for hydrostatic thrust bearing.

Download Full-text

Hydrodynamic Analysis of Hydrostatic Bearings With Runner Misalignment and Pad Damage

Volume 7B: Structures and Dynamics ◽

10.1115/gt2013-95951 ◽

2013 ◽

Author(s):

Timothy Dimond ◽

David Barnes

Keyword(s):

Film Thickness ◽

Analytical Solutions ◽

Thrust Bearing ◽

Load Capacity ◽

Element Solution ◽

Flow Loop ◽

Hydrodynamic Analysis ◽

Hydrostatic Bearing ◽

Hydrostatic Bearings ◽

Minimum Film Thickness

Hydrostatic bearings are used in applications where surface speeds are low, or viscosities are insufficient to develop significant load capacity due to shear flow. They are also used in jacking applications for initial liftoff of rotors under low or no rotation conditions, especially for heavy rotors where significant babbitt damage would otherwise occur. Traditional hydrostatic bearing analyses assume isothermal lubricating flows. Analytical solutions also assume that the pressure in the pocket of the hydrostatic bearing is constant. This assumption is only approximately correct for low and zero operating speeds. Analytical solutions also assume that the runner and pad surfaces are parallel. The analytical solutions are not capable of capturing damage or misalignment effects. This paper describes a hydrodynamic analysis of a hydrostatic thrust bearing. The solution is based on a finite element solution to the generalized Reynolds equation. The finite element solution is applied in both the pocket and pad regions of the hydrostatic bearings. The analysis includes a flow loop balance that considers the effects of pressure losses in the lubricant supply piping, allowing for modeling of saturation effects in bearing load capacity. The flow loop balance for the lubrication supply is coupled with the bearing solution. This allows for pad loads to vary as a function of circumferential position in thrust bearings. The analysis was applied to the operation of a hydrostatic thrust bearing system for the HUSIR radio telescope at the Massachusetts Institute of Technology. Simplified models of pad damage and runner misalignment were considered in the analysis. The minimum film thickness and pressure profile was calculated. Runner misalignment reduced minimum film thickness by up to 80% when compared to a parallel runner under identical loading conditions. Runner damage equivalent to twice the nominal film thickness reduced the minimum film thickness by approximately 10%.

Download Full-text

The Influence of Roughness on the Discharge Coefficient of a Broad-Crested Weir

Journal of Hydrology and Hydromechanics ◽

10.2478/v10098-012-0009-0 ◽

2012 ◽

Vol 60 (2) ◽

pp. 101-114 ◽

Cited By ~ 7

Author(s):

Jana Pařílková ◽

Jaromír Říha ◽

Zbyněk Zachoval

Keyword(s):

Discharge Coefficient ◽

Accurate Estimation ◽

Theoretical Knowledge ◽

Management Research ◽

Roughness Parameters ◽

Method Of Determination ◽

University Of Technology ◽

Research Faculty ◽

Theoretical Results

The Influence of Roughness on the Discharge Coefficient of a Broad-Crested Weir The use of environmentally-friendly materials in hydraulic engineering (e.g. the stone lining of weirs at levees) calls for the more accurate estimation of the discharge coefficient for broad-crested weirs with a rough crest surface. However, in the available literature sources the discharge coefficient of broad-crested weirs is usually expressed for a smooth crest. The authors of this paper have summarized the theoretical knowledge related to the effect of weir crest surface roughness on the discharge coefficient. The method of determination of the head-discharge relation for broad-crested weirs with a rough crest surface is proposed based on known discharge coefficient values for smooth surfaces and on the roughness parameters of the weir. For selected scenarios the theoretical results were compared with experimental research carried out at the Laboratory of Water Management Research, Faculty of Civil Engineering (FCE), Brno University of Technology (BUT).

Download Full-text

Numerical Simulation and Experimental Study of the Hydrostatic Spindle with Orifice Restrictors

The Open Mechanical Engineering Journal ◽

10.2174/1874155x01610010079 ◽

2016 ◽

Vol 10 (1) ◽

pp. 79-92

Author(s):

He Qiang ◽

Li Lili ◽

Ren Fengzhang ◽

Volinsky Alex

Keyword(s):

Thrust Bearing ◽

Rotation Speed ◽

Cold Drawing ◽

Rolling Bearings ◽

Element Analysis ◽

Rotating Speed ◽

Hydrostatic Bearing ◽

Fluid Flow Velocity ◽

Hydrostatic Bearings ◽

The Finite Element Analysis

Based on the theory of hydrostatic bearings, this paper presents a study of replacing the rolling bearings in a cold drawing spindle with the liquid hydrostatic bearings. An unloading mechanism is designed, containing two hydrostatic radial bearings and a thrust bearing, according to the mechanical characteristics of the spindle. In this study, a mathematical model of the hydrostatic bearing oil pad is developed. The effects of the rotating speed on pressure and flow fields of the oil pad are simulated using the finite element analysis and verified experimentally. The pressure in all recesses decreases with the rotation speed. Oil velocity of the radial hydrostatic bearing recess increases with the rotation speed, while the fluid flow velocity has almost no correlation with the rotation speed of the thrust bearing. The numerical and experimental results of the pressure in the recesses are consistent, confirming the validity and feasibility of this design.

Download Full-text

Simultaneous Determination of Antidiabetic Thiazolidinediones Using Flow Through Voltammetric Sensor

Current Pharmaceutical Analysis ◽

10.2174/1573412910666140818215811 ◽

2014 ◽

Vol 10 (4) ◽

pp. 239-245 ◽

Cited By ~ 1

Author(s):

Lai-Hao Wang ◽

Yan-Lin Song

Keyword(s):

Simultaneous Determination ◽

Voltammetric Sensor ◽

Flow Through

Download Full-text

Review of Research on Hydrostatic Bearings

Recent Patents on Mechanical Engineering ◽

10.2174/2212797613999201217124359 ◽

2020 ◽

Vol 13 ◽

Author(s):

Xiaodong Yu ◽

Yu Wang ◽

Junfeng Wang ◽

Wenkai Zhou ◽

Hongwei Bi ◽

...

Keyword(s):

High Speed ◽

Static Pressure ◽

Development Trend ◽

Cnc Machining ◽

Pressure Effects ◽

Cnc Machine Tools ◽

Future Research ◽

Theoretical Formula ◽

Hydrostatic Bearing ◽

Hydrostatic Bearings

Background: Hydrostatic bearings have the advantages of strong bearing capacity, good stability, small friction coefficient and long life. The performance of liquid hydrostatic bearings directly affect the accuracy and efficiency of CNC machining equipment. The performance is conducive to the development of CNC machine tools towards high speed and heavy load, so it is necessary to sort out and summarize the existing research results. Objective: This study summarizes the current development status of hydrostatic bearings and explains the development trend of hydrostatic bearings. Methods: According to the recently published journal articles and patents, the recent experimental research on hydrostatic thrust bearings is summarized. This paper summarizes many factors that affect the performance of hydrostatic bearings, and discusses the causes of various factors on hydrostatic bearings. Finally, future research on hydrostatic bearings is presented. Results: The study discusses experimental methods, simulation processes, and experimental results. Conclusion: This study can produce dynamic and static pressure effects by changing the structure of the oil cavity of the hydrostatic bearing. This effect can make up for the static pressure loss. By improving the theoretical formula and mathematical model and proposing a new simulation method, the accuracy of the hydrostatic bearing simulation is satisfied; the future development trend of the hydrostatic bearing is proposed.

Download Full-text

Determination of Environmental Factors for the Implementation of the Exploitability Index in Industrial Aggregate Mining Using Multi-Criteria Analysis

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi10040196 ◽

2021 ◽

Vol 10 (4) ◽

pp. 196

Author(s):

Julio Manuel de Luis-Ruiz ◽

Benito Ramiro Salas-Menocal ◽

Gema Fernández-Maroto ◽

Rubén Pérez-Álvarez ◽

Raúl Pereda-García

Keyword(s):

Environmental Factors ◽

Environmental Factor ◽

Human Life ◽

Accurate Estimation ◽

Analytic Hierarchy ◽

Main Components ◽

Hierarchy Process ◽

Made In

The quality of human life is linked to the exploitation of mining resources. The Exploitability Index (EI) assesses the actual possibilities to enable a mine according to several factors. The environment is one of the most constraining ones, but its analysis is made in a shallow way. This research is focused on its determination, according to a new preliminary methodology that sets the main components of the environmental impact related to the development of an exploitation of industrial minerals and its weighting according to the Analytic Hierarchy Process (AHP). It is applied to the case of the ophitic outcrops in Cantabria (Spain). Twelve components are proposed and weighted with the AHP and an algorithm that allows for assigning a normalized value for the environmental factor to each deposit. Geographic Information Systems (GISs) are applied, allowing us to map a large number of components of the environmental factors. This provides a much more accurate estimation of the environmental factor, with respect to reality, and improves the traditional methodology in a substantial way. It can be established as a methodology for mining spaces planning, but it is suitable for other contexts, and it raises developing the environmental analysis before selecting the outcrop to be exploited.

Download Full-text