A New Micro-Hydrodynamic Herringbone Bearing Using Slant Groove Depth Arrangements for Performance Enhancement

2017 ◽  
Vol 33 (5) ◽  
pp. 725-737
Author(s):  
Y. T. Lee ◽  
A. S. Yang ◽  
Y. H. Juan ◽  
C. S. Liu ◽  
Y. H. Chang
Keyword(s):  
Pressure Distribution ◽  
Performance Enhancement ◽  
Load Capacity ◽  
Three Dimensional ◽  
Measurement Data ◽  
Groove Depth ◽  
Friction Torque ◽  
Lubricant Film ◽  
Radial Stiffness ◽  
Good Agreement

AbstractThis study presents a new groove profile using the slant groove depth arrangements to enhance the performance of micro-HGJBs. The computational analysis was based on the steady-state three-dimensional conservation equations of mass and momentum in conjunction with the cavitation model to examine the complex lubricated flow field. The simulated results of load capacity and circumferential pressure distribution of lubricant film are in good agreement with the measurement data and the predictions cited in the literature. Numerical experiments were extended to determine the pressure distribution, load capacity, radial stiffness and friction torque by varying the slant ratio of groove depth, eccentricity ratio, rotational speed and attitude angle. The cavitation extent of lubricant film was also studied for different slant groove patterns.

Residual Stress Prediction for Non-Axisymmetric Vessel Penetration Welds

2008 ◽  
Author(s):  
Kazuo Ogawa ◽  
Nobuyoshi Yanagida ◽  
Koichi Saito
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Three Dimensional ◽  
Measurement Data ◽  
Fe Model ◽  
Stress Distributions ◽  
Dimensional Finite Element ◽  
Stress Prediction ◽  
Three Dimensional Finite Element ◽  
Good Agreement

Residual stress distribution in an oblique nozzle jointed to a vessel with J-groove welds was analyzed using a three-dimensional finite element method. All welding passes were considered in a 180-degree finite element (FE) model with symmetry. Temperature and stress were modeled for simultaneous bead laying. To determine residual stress distributions at the welds experimentally, a mock-up specimen was manufactured. The analytical results show good agreement with the experimental measurement data, indicating that FE modeling is valid.

scholarly journals Design and analysis of flow rectifier of gas turbine flowmeter

2013 ◽  
Vol 17 (5) ◽  
pp. 1504-1507 ◽  
Author(s):  
Zhi-Fei Li ◽  
Zheng Du ◽  
Kai Zhang ◽  
Dong-Sheng Li ◽  
Zhong-Di Su ◽  
...  
Keyword(s):  
Experimental Data ◽  
Flow Field ◽  
Computational Model ◽  
Pressure Distribution ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Pressure Loss ◽  
Three Dimensional ◽  
Turbine Flowmeter ◽  
Good Agreement

Three-dimensional computational model for a gas turbine flowmeter is proposed, and the finite volume based SIMPLEC method and k-? turbulence model are used to obtain the detailed information of flow field in turbine flowmeter, such as velocity and pressure distribution. Comparison between numerical results and experimental data reveals a good agreement. A rectifier with little pressure loss is optimally designed and validated numerically and experimentally.

Correlation-Based Riblet Model for Turbomachinery Applications

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Viktor Koepplin ◽  
Florian Herbst ◽  
Joerg R. Seume
Keyword(s):  
Three Dimensional ◽  
Measurement Data ◽  
Navier Stokes ◽  
Pressure Gradients ◽  
Compressor Cascade ◽  
Design Code ◽  
Experimental Values ◽  
Turbomachinery Design ◽  
Plate Measurement ◽  
Good Agreement

An empirical riblet model for manufactured V-shaped and trapezoidal riblets which is suitable for turbomachinery application is presented. The implementation of the riblet effect employs a correlation-based correction for the damping of the specific dissipation rate ω in the vicinity of the wall which has been previously presented by other researchers. In the current paper, the correlations are extended into the drag-increasing regime and are extended to account for the effect of misalignment of the riblets relative to the flow and for the effect of adverse pressure gradients. In order to account for the latter in modern, massive parallel Reynolds-averaged Navier–Stokes (RANS) codes, a local Clauser parameter has been newly derived. The model is implemented in a three-dimensional (3D) turbomachinery design code and validated with flat plate measurement data and a NACA6510 compressor cascade. The predictions of the experimental values are in very good agreement with the experimental data, showing the capability of the model for designing riblet structured turbomachinery blading.

The Influence of Surface Patterning on the Thermal Properties of Textured Thrust Bearings

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Gen Fu ◽  
Alexandrina Untaroiu
Keyword(s):  
Surrogate Model ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Three Dimensional ◽  
Major Axis ◽  
Friction Torque ◽  
Design Parameters ◽  
Textured Surfaces ◽  
Lubricated Contacts ◽  
Radial Extent

Contact performance can be enhanced by using textured surfaces. These are also found to have influences on lubricated contacts. A procedure to find the optimal partially textured thrust bearing configuration is presented in this study. A parallel sector-pad thrust bearing is simulated by a three-dimensional (3D) computational fluid dynamics (CFD) model. The stationary surface of the bearing is textured with dimples, while the rotor surface is flat. The results of the baseline model are validated by experimental data. In this study, we compare rectangular and elliptical dimples by investigating design parameters, such as major the length of the major axis (width), the length of the minor axis (length), dimple depth, circumferential space between two dimples, radial space between two dimples, radial extent, circumferential extent are selected as design parameters. A parametric study is conducted to investigate the influence of the texture geometries and a surrogate model is created. Based on the surrogate model, a multi-objective optimization scheme is used to navigate the design space and find the optimal texture structure that provides a lower maximal temperature inside the fluid film, higher load capacity, and lower friction torque. The results show that the optimal radial extent of the texture is around 80% of the pad radial length for both cases. The optimal length of the elliptical dimples in the circumferential direction is about 30% larger than the value of the rectangular dimples. In the final optimal design, the maximal temperature reduces 1.1% and 1.3% for rectangular and elliptical dimples while the load capacities are maintained at the same level.

On the Field of Temperatures in Lubricating Films

1967 ◽  
Vol 89 (4) ◽  
pp. 483-491 ◽  
Author(s):  
N. Tipei ◽  
Al. Nica
Keyword(s):  
Temperature Distribution ◽  
Pressure Distribution ◽  
Energy Equation ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Dimensional Case ◽  
Experimental Measurements ◽  
Lubricating Film ◽  
Good Agreement

The temperature distribution in the lubricating film of journal bearings for the three-dimensional case is obtained by using the results already known regarding the pressure distribution in the film and by integrating the energy equation. Relations for the divergent and convergent zones of the bearing are established by taking into account the viscosity and the side leakage; the distribution of the temperature along the bearing width is also considered. Comparisons between the theoretical values and experimental measurements are also performed, resulting in good agreement.

Performance of novel air foil thrust bearings with taper-groove on surface of top foil

2020 ◽  
Vol 235 (1) ◽  
pp. 79-92
Author(s):  
Hongyang Hu ◽  
Ming Feng
Keyword(s):  
Film Thickness ◽  
Thrust Bearing ◽  
Load Capacity ◽  
Groove Depth ◽  
Friction Torque ◽  
Width Ratio ◽  
Local Dynamic ◽  
The Novel ◽  
Rarefaction Effect ◽  
Foil Thrust Bearing

To improve the load capacity of air foil thrust bearing, the micro taper-grooves on the surface of top foil was introduced and studied. A modified Reynolds equation considering the gas rarefaction effect was established, in which the Knudsen number was affected by the film thickness and pressure. A new bump stiffness model was built with the consideration of bump rounding, friction, and bending stiffness of foil. By considering the variation of gas film thickness, the load capacity, friction torque, and power loss of novel bearing with grooves were calculated by the finite difference method. Moreover, the effect law of groove parameters, groove shape and grooves number on the novel bearing performance was studied systematically. The results show that the predicted axial load capacity considering gas rarefaction effect is decreased slightly in smaller clearance and more consistent with the actual test data. The novel air foil thrust bearing with taper-groove can weaken the air end leakage and enhance the local dynamic pressure efficiently in the parallel portion of top foil, thus improving the static characteristics of bearing. For the novel air foil thrust bearing with taper-groove depth of 10 µm, the load capacity can be increased by about 13.33%, compared with traditional bearing. With the increments of taper-groove depth and length on top foil, the load capacity can be increased. However, the friction torque is decreased when there is a longer taper-groove in the circumferential direction. Meanwhile, the optimal groove width ratio is about 0.5, and the structure of multi-grooves is beneficial to the decreased friction torque. The validity of presented theoretical model has been verified by the literature data, and the results are expected to be helpful to bearing designers, researchers, and academicians concerned.

Calculation of the Hydroplaning of a Deformable Smooth-Shaped and Longitudinally-Grooved Tire

1997 ◽  
Vol 25 (4) ◽  
pp. 265-287 ◽  
Author(s):  
H. Grogger ◽  
M. Weiss
Keyword(s):  
Pressure Distribution ◽  
Contact Area ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Water Film ◽  
Iterative Solution ◽  
Groove Depth ◽  
Surface Model ◽  
Finite Element Program ◽  
Lift And Drag

Abstract The dynamic hydroplaning of a deformable automobile tire is calculated. The three-dimensional flow around the tire is described by an efficient free surface model and the Navier-Stokes equations. The effects of turbulence are modeled by the well-known k,ε-model. The deformation of the tire is calculated using a noncommercial finite element program, in which all components of the three-dimensional tire are taken into account with their own mechanical and constitutive behavior. The deformation of the tire during stationary hydroplaning is found by an iterative solution procedure. The result of the calculation is the pressure distribution and the velocity field. The integration of the pressure distribution acting on the tire surface yields the lift and drag forces as well as lift and drag coefficients. The calculations are performed for a smooth-shaped tire at speeds of 30, 60, and 90 km/h driving speed and an 8 mm high water film. The results are compared with those of the undeformable tire. The calculated pressure distribution on the pavement shows very good agreement with experimentally obtained data. At 90 km/h the model predicts that the water penetrates the contact area of the tire whereas the tire still has contact with the road in the shoulder area. This is also found in experiments. Further, calculations are performed for a deformable tire with three circumferential grooves. Here the influence of different water depths at a speed of 90 km/h is investigated. The groove depth of the tire is 8 mm whereas the water depth varies between 4, 8, and 12 mm. The calculations show the intrusion of a water wedge into the contact area. As in previous studies it is found that the tire deformation has a very strong influence on the resulting lift forces.

Analysis of the Contact Deformation of a Radial Tire with Camber Angle

1995 ◽  
Vol 23 (1) ◽  
pp. 26-51 ◽  
Author(s):  
S. Kagami ◽  
T. Akasaka ◽  
H. Shiobara ◽  
A. Hasegawa
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Contact Region ◽  
Contact Deformation ◽  
Contact Pressure Distribution ◽  
Radial Tire ◽  
Ring Model ◽  
Camber Angle ◽  
Contact Free ◽  
Good Agreement

Abstract The contact deformation of a radial tire with a camber angle, has been an important problem closely related to the cornering characteristics of radial tires. The analysis of this problem has been considered to be so difficult mathematically in describing the asymmetric deformation of a radial tire contacting with the roadway, that few papers have been published. In this paper, we present an analytical approach to this problem by using a spring bedded ring model consisting of sidewall spring systems in the radial, the lateral, and the circumferential directions and a spring bed of the tread rubber, together with a ring strip of the composite belt. Analytical solutions for each belt deformation in the contact and the contact-free regions are connected by appropriate boundary conditions at both ends. Galerkin's method is used for solving the additional deflection function defined in the contact region. This function plays an important role in determining the contact pressure distribution. Numerical calculations and experiments are conducted for a radial tire of 175SR14. Good agreement between the predicted and the measured results was obtained for two dimensional contact pressure distribution and the camber thrust characterized by the camber angle.

A Free Energy Perturbation Approach to Estimate the Intrinsic Solubilities of Drug-like Small Molecules

2019 ◽  
Author(s):  
Sayan Mondal ◽  
Gary Tresadern ◽  
Jeremy Greenwood ◽  
Byungchan Kim ◽  
Joe Kaus ◽  
...  
Keyword(s):  
Solid State ◽  
Small Molecules ◽  
Three Dimensional ◽  
Aqueous Solubility ◽  
Computational Approach ◽  
Free Energy Perturbation ◽  
Perturbation Approach ◽  
Energy Perturbation ◽  
State Form ◽  
Good Agreement

<p>Optimizing the solubility of small molecules is important in a wide variety of contexts, including in drug discovery where the optimization of aqueous solubility is often crucial to achieve oral bioavailability. In such a context, solubility optimization cannot be successfully pursued by indiscriminate increases in polarity, which would likely reduce permeability and potency. Moreover, increasing polarity may not even improve solubility itself in many cases, if it stabilizes the solid-state form. Here we present a novel physics-based approach to predict the solubility of small molecules, that takes into account three-dimensional solid-state characteristics in addition to polarity. The calculated solubilities are in good agreement with experimental solubilities taken both from the literature as well as from several active pharmaceutical discovery projects. This computational approach enables strategies to optimize solubility by disrupting the three-dimensional solid-state packing of novel chemical matter, illustrated here for an active medicinal chemistry campaign.</p>

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