Numerical Study of Cage Dynamics Focused on Hydrodynamic Effects of Guidance Land Clearances for Different Ball-Pocket Clearances in Cryogenic Environments

2017 ◽  
Author(s):  
Bok Seong Choe ◽  
Jeon Kook Lee ◽  
Doyoung Jeon ◽  
Yongbok Lee
Keyword(s):  
Ball Bearing ◽  
Rotation Speed ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Cfd Analysis ◽  
Dynamic Motion ◽  
Light Load ◽  
Dynamic Forces ◽  
Inner Race

This study presents the dynamic motion of a ball bearing cage submerged in a cryogenic fluid under high-speed conditions. The dynamic motion of the cage has been studied as a function of the race land–cage and ball–cage pocket clearances for different inner race rotation speeds under light load conditions. In addition, this study conducted computational fluid dynamics (CFD) analysis using commercial software to analyze the fluid dynamic forces on the cage. The hydraulic force obtained from the CFD analysis was coded in commercial ball bearing analysis software as a function of the eccentricity ratio and rotation speed of the cage. Finally, the dynamic motion of the ball bearing cage considering the effects of fluid dynamic forces has been studied. The results include the cage whirling amplitude, fluctuation of cage whirling speed, and cage wear for various cage clearances and rotation speeds. The cage outer guidance clearances studied were 1.14, 1.04, 0.94, 0.84, and 0.74 mm and the ball–pocket clearances were 0.62, 0.92, 1.22, 1.52, and 1.82 mm. The rotation speeds of the inner race were 5,000, 8,000, and 11,000 rpm. The cage whirling amplitude decreases as the outer guidance clearance decreases, and it decreases as the rotation speed increases up to 11,000 rpm because of the increasing hydrodynamic force of the liquid nitrogen (LN2). However, the probability density function (PDF) curves indicate that an increase in the rotor speed increases the standard deviation in the cage whirling frequency. The wear loss of the cage was greatest for the largest race land–cage and the smallest ball–cage pocket clearances, owing to the increased number of intermittent collisions between the cage and the ball bearings (ball–race). Consequently, the analysis results for various operating conditions (inner race rotation speeds, cage clearances, traction coefficients, etc.) are in good agreement with the reference results.

Numerical Study of Cage Dynamics Focused on Hydrodynamic Effects of Guidance Land Clearances for Different Ball-Pocket Clearances in Cryogenic Environments

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Bokseong Choe ◽  
Jeonkook Lee ◽  
Doyoung Jeon ◽  
Yongbok Lee
Keyword(s):  
Ball Bearing ◽  
Rotation Speed ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Cfd Analysis ◽  
Dynamic Motion ◽  
Light Load ◽  
Dynamic Forces ◽  
Inner Race

This study presents the dynamic motion of a ball bearing cage submerged in a cryogenic fluid under high-speed conditions. The dynamic motion of the cage has been studied as a function of the race land-cage and ball-cage pocket clearances for different inner race rotation speeds under light load conditions. In addition, this study conducted computational fluid dynamics (CFD) analysis using commercial software to analyze the fluid dynamic forces on the cage. The hydraulic force obtained from the CFD analysis was coded in commercial ball bearing analysis software as a function of the eccentricity ratio and rotation speed of the cage. Finally, the dynamic motion of the ball bearing cage considering the effects of fluid dynamic forces has been studied. The results include the cage whirling amplitude, fluctuation of cage whirling speed, and cage wear for various cage clearances and rotation speeds. The cage whirling amplitude decreases as the outer guidance clearance decreases, and it decreases as the rotation speed increases up to 11,000 rpm because of the increasing hydrodynamic force of the liquid nitrogen (LN2). However, the probability density function curves indicate that an increase in the rotor speed increases the standard deviation in the cage whirling frequency. The wear loss of the cage was greatest for the largest race land-cage and the smallest ball-cage pocket clearances. Consequently, the analysis results for various operating conditions (inner race rotation speeds, cage clearances, traction coefficients, etc.) are in good agreement with the reference results.

Experiments on the lift and drag of spheres suspended in a Poiseuille flow

1964 ◽  
Vol 20 (3) ◽  
pp. 513-527 ◽  
Author(s):  
R. Eichhorn ◽  
S. Small
Keyword(s):  
Reynolds Number ◽  
Poiseuille Flow ◽  
Rotation Speed ◽  
Fluid Dynamic ◽  
Particle Diameter ◽  
Dynamic Forces ◽  
Shear Parameter ◽  
Fluid Properties ◽  
Approach Velocity ◽  
Lift And Drag

An experimental investigation of the fluid dynamic forces on spheres suspended in a Poiseuille flow was performed. Small spheres of polystyrene, nylon, and Lucite, having diameters ranging from 0.061 in. to 0.126 in. were suspended in Poiseuille flows in a 0.419 in. diameter tube. Variations in particle size and density, the fluid properties, and the angle of inclination of the tube, resulted in a sphere Reynolds number (based on particle diameter and approach velocity) ranging from 80 to 250. The results are presented as curves which include the coefficients of lift and drag, and the dimensionless rotation speed plotted versus Reynolds number and a dimensionless shear parameter.

Experimental and Numerical Study of Stall Flutter in a Transonic Low-Aspect Ratio Fan Blisk

2003 ◽  
Author(s):  
A. J. Sanders ◽  
K. K. Hassan ◽  
D. C. Rabe
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Strain Gages ◽  
Pressure Transducers ◽  
Low Aspect Ratio ◽  
Benchmark Data

Experiments are performed on a modern design transonic shroudless low-aspect ratio fan blisk that experienced both subsonic/transonic and supersonic stall-side flutter. High-response flush mounted miniature pressure transducers are utilized to measure the unsteady aerodynamic loading distribution in the tip region of the fan for both flutter regimes, with strain gages utilized to measure the vibratory response at incipient and deep flutter operating conditions. Numerical simulations are performed and compared with the benchmark data using an unsteady three-dimensional nonlinear viscous computational fluid dynamic (CFD) analysis, with the effects of tip clearance, vibration amplitude, and the number of time steps-per-cycle investigated. The benchmark data are used to guide the validation of the code and establish best practices that ensure accurate flutter predictions.

Ball Bearing Response to Cage Unbalance

1986 ◽  
Vol 108 (3) ◽  
pp. 462-466 ◽  
Author(s):  
P. K. Gupta ◽  
J. F. Dill ◽  
J. W. Artuso ◽  
N. H. Forster
Keyword(s):  
Entire Range ◽  
High Speed ◽  
Ball Bearing ◽  
Operating Conditions ◽  
Angular Contact Ball Bearing ◽  
Turbine Engine ◽  
Wide Range ◽  
Inner Race ◽  
Good Agreement ◽  
Engine Bearing

Motion of the cage in a high-speed angular contact ball bearing is experimentally investigated as a function of prescribed unbalance, up to operating speeds corresponding to three million DN. The predictions of cage motion made by the recently developed computer model, ADORE, are validated in the light of the experimental data. It is shown the cage whirl velocity is essentially equal to its angular velocity at all levels of unbalance and over a wide range of operating conditions. For the inner race guided turbine engine bearing, the cage/race interaction takes place directly opposite to the location of the unbalance and the severity of the interaction increases with the level of unbalance and the operating speed. ADORE predictions, over the entire range of unbalance and bearing operating conditions, are in very good agreement with the experimental observations.

Numerical Study on Flow around Three Circular Piers in Tandem Arrangement at a Supercritical Reynolds Number

2012 ◽  
Vol 170-173 ◽  
pp. 1932-1937
Author(s):  
Peng Hao ◽  
Guo Dong Li ◽  
Lan Yang ◽  
Gang Chen
Keyword(s):  
Reynolds Number ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Two Dimensional ◽  
Lateral Loads ◽  
Dynamic Design ◽  
Tandem Arrangement ◽  
Dynamic Forces ◽  
Les Model ◽  
Supporting Structures

As the support structures of building for crossing river, piers of bridge and/or aqueduct are generally arranged in tandem along the river direction, the fluid dynamic forces are main lateral loads acting on the Piers. Two-dimensional fluid computations have been performed using LES model to investigate the flows around three circular piers in tandem arrangements at a supercritical Reynolds number, Re =8.76×106. Both center-to-center spaces are L/D=2.6. The flows and fluid-dynamic forces obtained from the simulations are analyzed. The results can provide the basis for the dynamic design of the supporting structures of the aqueducts.

Numerical Study of the Co-Firing Pulverized Coal and Biomass

2012 ◽  
Vol 170-173 ◽  
pp. 3419-3424
Author(s):  
Yu Ting Cheng ◽  
Zhao Peng Jia ◽  
Shi Liu
Keyword(s):  
Gas Phase ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Complex Problem ◽  
Cfd Analysis ◽  
Radiation Model ◽  
Saw Dust ◽  
Turbulence Flow ◽  
Reduction Of Co2 ◽  
Pdf Model

This study presented Computational Fluid Dynamic (CFD) analysis of the effect of co-firing coal blended with biomass, which is saw dust here. This complex problem which is because of its turbulent on the chemical reactions has been simulated in this paper for the purpose to decline the large amount of cost of doing experiment. The CFD analysis includes the prediction of vectors of the gas phase and DPM burnout result alike. What’s more, the reduction of CO2 by coal blended with different proportions of biomass has been presented because of low content of char in biomass. The mathematical models consist of models for turbulence flow(RNG K-EPSILON MODEL);non-premixed model with two mixture fractions/PDF model; and radiation (P-1 radiation model). The coal is from An Qin in China, and then respectively blended with 5% and 10% saw dust for co-combustion.

scholarly journals Preliminary CFD Assessment of an Experimental Test Facility Operating with Heavy Liquid Metals

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Matteo Lizzoli ◽  
Walter Borreani ◽  
Francesco Devia ◽  
Guglielmo Lomonaco ◽  
Mariano Tarantino
Keyword(s):  
Experimental Data ◽  
Liquid Metals ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Test Facility ◽  
Cfd Analysis ◽  
Cfd Model ◽  
Cfd Simulations ◽  
Pressure Drops ◽  
Venturi Nozzle

The CFD analysis of a Venturi nozzle operating in LBE (key component of the CIRCE facility, owned by ENEA) is presented in this paper. CIRCE is a facility developed to investigate in detail the fluid-dynamic behavior of ADS and/or LFR reactor plants. The initial CFD simulations have been developed hand in hand with the comparison with experimental data: the test results were used to confirm the reliability of the CFD model, which, in turn, was used to improve the interpretation of the experimental data. The Venturi nozzle is modeled with a 3D CFD code (STAR-CCM+). Later on, the CFD model has been used to assess the performance of the component in conditions different from the ones tested in CIRCE: the performance of the Venturi is presented, in terms of pressure drops, for various operating conditions. Finally, the CFD analysis has been focused on the evaluation of the effects of the injection of an inert gas in the flow of the liquid coolant on the performance of the Venturi nozzle.

An Archimedean Screw Based Energy Harvester for Oil Extraction, Water Injection, and Related Activities

2019 ◽  
Author(s):  
Rui Lin ◽  
Boxi Jiang ◽  
Lei Zuo
Keyword(s):  
Energy Harvester ◽  
Numerical Study ◽  
Water Injection ◽  
Oil Extraction ◽  
Operating Conditions ◽  
Outer Diameter ◽  
Resistive Load ◽  
Cfd Analysis ◽  
Injection Wells ◽  
Optimal Geometry

Abstract This paper presents an Archimedean Screw Turbine (AST) based energy harvester designed to power wireless sensor system inside oil extraction or water injection wells. Numerical study has been carried out using CFD analysis to evaluate the performance of the harvester. Characteristics of the AST, including turbine length, blade pitch, and rotational speed were studied to determine the optimal geometry and operating conditions of the system. An AST prototype with a length of 85 mm and an outer diameter of 50 mm was fabricated through 3D printing and in-lab tests were conducted to validate the performance of the designed harvester. A maximum power output of 0.21 W was achieved under a constant pipe flow rate of 0.95 liter per second when an external resistive load of 10 Ω was connected to the harvester. Lastly, the experimental results were analyzed and compared to the CFD analysis.

Numerical Study of SI Engine Part Load Operating Conditions Using Different VVA Strategies

2011 ◽  
Author(s):  
Michele Battistoni ◽  
Carlo N. Grimaldi ◽  
Francesco Mariani
Keyword(s):  
Numerical Study ◽  
Control Strategies ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Load Control ◽  
Valve Closure ◽  
Intake Valve ◽  
Flamelet Model ◽  
Part Load ◽  
Engine Model

In SI engines, VVA (Variable Valve Actuation) technology is mainly used for the reduction of pumping losses at part load. This paper presents the results of fluid dynamic analyses on a 4V engine about the effects of different VVA strategies, by comparing and discussing the results in terms of organized charge motions, turbulence levels, flame developments, NO and CO emissions. CFD simulations cover five load control cases: comparison is among conventional throttling, EIVC (Early Intake Valve Closure) with symmetric and asymmetric intake lifts, LIVC (Late Intake Valve Closure) and symmetrical Multi-Lift strategies. 3D U-RANS simulations are performed, adopting the Extended Coherent Flamelet Model (ECFM) for the description of premixed SI combustion. The 3D model is also coupled to a 1D engine model which provides inlet/outlet boundary conditions. Simulation results highlight the potential of asymmetric Early Intake Valve Closure (EIVC) strategy which allows reducing pumping losses and, at the same time, achieving good turbulence intensity and combustion speed, if compared to other load control strategies. Multi-Lift strategy resulted excellent in terms of burn duration, but pumping losses are practically the same as in the throttled engine.

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