Analysis of Incomplete Film in Parallel Plates Including Inlet Tube and Groove

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Shanshan Wei ◽  
Haibo Zhang ◽  
Yuri Kligerman ◽  
Roman Goltsberg ◽  
Izhak Etsion
Keyword(s):  
Present Model ◽  
Design Parameters ◽  
Bottom Plate ◽  
Parallel Plates ◽  
Empirical Expression ◽  
System A ◽  
Inlet Tube ◽  
Mass Flowrate ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Abstract To clarify the realistic upstream boundary conditions of hydrodynamic bearings, the oil spread in a complex system of parallel plates including an inlet tube and axial groove is studied by the computational fluid dynamics (CFD) method. The effects of various design parameters including clearance, velocity of bottom plate, and inlet mass flowrate on oil spread-length are presented and explained. By intensive parametric study for these parameters, an empirical expression for the oil spread-length is derived. A groove with blind ends significantly increases the efficiency of the system. A comparison with experimental observation validates the present model as a proper one for accurately solving oil spread in similar systems.

CFD Analysis of a Water Flume Design for Testing Marine and Hydrokinetics Energy Converters

2018 ◽  
Author(s):  
Akshith Subramanian ◽  
Navid Goudarzi
Keyword(s):  
Test Section ◽  
Lower Cost ◽  
Performance Metrics ◽  
Experimental Testing ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Design Parameters ◽  
Energy Technologies ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Marine and hydrokinetic (MHK) energy resources with advantages such as predictability and less variability compared to other forms of renewable energies, have been drawing more interest in recent years. One important phase before commercialization of new MHK technologies is to conduct experimental testing and evaluate their performance in a real environment. In this work, a numerical computational fluid dynamics (CFD) method is used to study the fluid flow behavior within a designed water flume for MHK energy technologies. The water flume design parameters were given by the team collaborators at National Renewable Energy Laboratory (NREL) and Colorado School of Mines. The results from this simulation showed the flow characteristics within the test-section of the proposed water flume design. These results can be used for the follow on phases of this research that includes testing scaled MHK prototypes at different flow rates as well as optimizing either the water flume design to obtain more realistic flow characteristics within the test section or the MHK devices to obtain higher performance metrics at lower cost.

Simulation Study on Ventilation & Cooling for an Indoor Substation

2014 ◽  
Vol 672-674 ◽  
pp. 1700-1707 ◽  
Author(s):  
Rui Xu ◽  
Zhong Min Mei ◽  
Ting Fang Yu
Keyword(s):  
Natural Ventilation ◽  
Three Dimensional ◽  
Organization Design ◽  
Temperature Fields ◽  
Design Parameters ◽  
Air Distribution ◽  
Safety And Reliability ◽  
Computational Fluid Dynamics Cfd ◽  
Dimensional Simulation ◽  
Cfd Method

— Based on natural ventilation design scheme for an indoor substation, different air distribution schemes were obtained by changing height and size of air inlets and outlets. For indoor substation, three-dimensional simulation of air distribution was conducted by using Computational Fluid Dynamics (CFD) method. Ventilation & cooling effect of different indoor ventilation schemes were simulated with software (Fluent). By analyzing velocity fields and temperature fields, influences of different design parameters on safety and reliability of main transformer room of indoor substation were compared and analyzed in details. Additionally, characteristics and change rules of air distribution with different parameter variations were concluded. Considerations of ventilation organization design for main transformer room of indoor substation and recommendation for better air distribution schemes were provided. The research results also offered some guidance for design and renovation of ventilation & cooling projects of indoor substation.

A Universal Semi-Analytic Model for Axial Mixing in a Straight Pipe

2014 ◽  
Author(s):  
Heng Luo ◽  
Yun Li ◽  
Hai Wang
Keyword(s):  
Present Model ◽  
Numerical Solutions ◽  
Turbulent Viscosity ◽  
Industrial Applications ◽  
Straight Pipe ◽  
Safety And Reliability ◽  
Computational Fluid Dynamics Cfd ◽  
Relative Errors ◽  
Cfd Method ◽  
Key Parameter

The industrial applications of common pipelines to simultaneously deliver multiple types of gases or liquids widely occur in petroleum and natural gas industries. Therein, the pipelines compose of significant horizontal and vertical sections can range from several meters to several km in length. The longitudinal dispersion of matter is an important aspect of such flows in safety and reliability. This paper sets out an analytic simulation model on the basis of the profiles of velocity and turbulent viscosity via steady numerical solutions by computational fluid dynamics (CFD) method. The mixing length and the wasting lengths of the original and latter fluids were applied as the key parameter to describe the extent of axial mixing in the pipe. In both turbulent and laminar pipe flows, the relative errors in the present model were reduced to 5% or less, which is 5%–15% lower than those in previous models. Moreover, the accuracy of the present model was nearly not less than that of unsteady numerical solutions in the same meshing density, whereas the computational load of the present model was far less than that of unsteady numerical solutions. Further, through investigating effects of buoyancy on axial mixing, it is found that the wasting length of the lighter fluid was higher than that of the heavier fluid.

scholarly journals Numerical Analysis of Flow across Brush Elements Based on a 2-D Staggered Tube Banks Model

Aerospace ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 19
Author(s):  
Xiaolei Song ◽  
Meihong Liu ◽  
Xiangping Hu ◽  
Xueliang Wang ◽  
Taohong Liao ◽  
...  
Keyword(s):  
Euler Number ◽  
Dynamic Pressure ◽  
Labyrinth Seals ◽  
System A ◽  
Brush Seal ◽  
Back Plate ◽  
Computational Fluid Dynamics Cfd ◽  
Secondary Air ◽  
Tube Banks ◽  
Gas Expansion

In order to improve efficiency in turbomachinery, brush seal replaces labyrinth seals widely in the secondary air system. A 2-d staggered tube bank model is adopted to simulate the gas states and the pressure character in brush seal, and computational fluid dynamics (CFD) is used to solve the model in this paper. According to the simulation results, the corrected formula of the Euler number and dimensionless pressure are given. The results show that gas expands when flow through the bristle pack, and the gas expansion closes to an isotherm process. The dynamic pressure increases with decreasing static pressure. The Euler number can reflect the seal performance of brush seals in leakage characteristics. Compared with increasing the number of rows, the reduction of the gap is a higher-efficiency method to increase the Euler number. The Euler number continually increases as the gap decreases. However, with the differential pressure increasing, Euler number first increases and then decreases as the number of rows increases. Finally, the pressure distribution on the surface of end rows is asymmetric, and it may increase the friction between the bristles and the back plate.

Bearing Performance Limits With Grease Lubrication

2005 ◽  
Author(s):  
P. M. Cann ◽  
A. A. Lubrecht
Keyword(s):  
Surface Damage ◽  
Design Parameters ◽  
Performance Limits ◽  
Grease Lubrication ◽  
Lubricated Contacts ◽  
System A ◽  
Operating Limits ◽  
Bearing Design ◽  
Cage Effects ◽  
Efficient Mechanisms

This paper has examined the influence of bearing design and operation in controlling lubricant supply to the contact zone. Grease lubricated contacts are liable to starvation and as a result the film thickness is reduced, this can result in surface damage or premature bearing failure. It is of obvious importance to know when starvation occurs and the effect of grease type, bearing design and operation on lubrication replenishment. The aim therefore is to develop a starvation parameter capable of predicting the operating limits for a particular bearing/grease system. A number of bearing design parameters are examined in the paper, these include cage design, ball spin and bearing size. Ball spin and cage effects can be efficient mechanisms for maintaining the lubricant supply to the track. Increased bearing size, line contact geometries and high load result in reduced lubricant replenishment of the contact. Using this analysis it will be possible to establish operating limits for families of bearings.

Investigation of sustainability of lubricated journal bearing under relevant design parameters

2018 ◽  
Vol 70 (4) ◽  
pp. 789-804 ◽  
Author(s):  
M.M. Shahin ◽  
Mohammad Asaduzzaman Chowdhury ◽  
Md. Arefin Kowser ◽  
Uttam Kumar Debnath ◽  
M.H. Monir
Keyword(s):  
Aspect Ratio ◽  
Elastic Strain ◽  
Journal Bearing ◽  
Design Parameters ◽  
Content Type ◽  
Computational Fluid Dynamics Cfd ◽  
Stress Formation ◽  
Bearing Design ◽  
The Stability ◽  
Bearing Friction

Purpose The purposes of the present study are to ensure higher sustainability of journal bearings under different applied loads and to observe bearing performances such as elastic strain, total deformation and stress formation. Design/methodology/approach A journal bearing test rig was used to determine the effect of the applied load on the bearing friction, film thickness, lubricant film pressure, etc. A steady-state analysis was performed to obtain the bearing performance. Findings An efficient aspect ratio (L/D) range was obtained to increase the durability or the stability of the bearing while the bearing is in the working condition by using SAE 5W-30 oil. The results from the study were compared with previous studies in which different types of oil and water, such as Newtonian fluid (NF), magnetorheological fluid (MRF) and nonmagnetorheological fluid (NMRF), were used as the lubricant. To ensure a preferable aspect ratio range (0.25-0.50), a computational fluid dynamics (CFD) analysis was conducted by ANSYS; the results show a lower elastic strain and deformation within the preferable aspect ratio (0.25-0.50) rather than a higher aspect ratio using the SAE 5W-30 oil. Originality/value It is expected that the findings of this study will contribute to the improvement of the bearing design and the bearing lubricating system.

An anti-crystallization design of selective catalytic reduction nozzle holder

2021 ◽  
pp. 095440702097084
Author(s):  
Dewen Liu ◽  
Kai Lu ◽  
Shusen Liu ◽  
Yan Wu ◽  
Shuzhan Bai
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Injection System ◽  
Test Results ◽  
Verification Methods ◽  
Crystallization Risk ◽  
Protective Cover ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Good Agreement

From the aspect of reducing the risk of crystallization on nozzle surface, a new design of nozzle protective cover was to solve the problem in selective catalytic reduction (SCR) urea injection system. The simulation calculation and experimental verification methods were used to compare different schemes. The results show that reducing the height of nozzle holder can reduce the vortex currents near nozzle surface and effectively reduce the risk of crystallization on the nozzle surface. It is proposed to install a protective cover in the nozzle holder under the scheme of reducing the height of nozzle holder, which can further eliminate the vortex. Simulation and test results demonstrate good agreement under the rated running condition. The scheme of adding a protective cover in the nozzle holder shows the least crystallization risk by computational fluid dynamics (CFD) method. The crystallization cycle test shows that, after the height of nozzle holder is reduced, the risk of crystallization on the nozzle surface is reduced correspondingly. The addition of a protective cover in the nozzle holder solves the problem of crystallization on the nozzle surface, which provides a new method for anti-crystallization design.

A Parametric Examination of the Factors Affecting the Performance of a Diffusion Absorption Refrigeration System

2021 ◽  
pp. 1-38
Author(s):  
Noman Yousuf ◽  
Timothy Anderson ◽  
Roy Nates
Keyword(s):  
Waste Heat ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Low Grade ◽  
Absorption Refrigeration ◽  
Factors Affecting ◽  
Thermally Driven ◽  
Mass Flowrate ◽  
Diffusion Absorption

Abstract Despite being identified nearly a century ago, the diffusion absorption refrigeration (DAR) cycle has received relatively little attention. One of the strongest attractions of the DAR cycle lies in the fact that it is thermally driven and does not require high value work. This makes it a prime candidate for harnessing low grade heat from solar collectors, or the waste heat from stationary generators, to produce cooling. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. In this vein, this work developed a new parametric model that can be used to examine the performance of the DAR cycle for a range of operating conditions. The results showed that the cycle's performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flowrate of the refrigerant and the type of the working fluid. It was shown that can deliver good performance at low generator temperatures if the refrigerant mass fraction in the strong solution is made as high as possible. Moreover, it was shown that a H2O-LiBr working pair could be useful for achieving cooling at low generator temperatures.

Romantic Passion as Output from a Self-Regulating, Intimacy-Seeking System: A Model for Understanding Passionate Love

2005 ◽  
Vol 96 (3) ◽  
pp. 655-675 ◽  
Author(s):  
Adam B. Troy
Keyword(s):  
Intimate Relationships ◽  
Present Model ◽  
Self Regulation ◽  
Personality Theory ◽  
Basic Emotion ◽  
Passionate Love ◽  
System A ◽  
Romantic Passion ◽  
Regulation Model ◽  
And Function

This article presents a model of why individuals experience the feeling of passionate love in intimate relationships. Previous models have been limited because they do not describe the purpose and function of passionate love, do not incorporate basic emotion and personality theory, or are not applicable to help couples in distress. The present model reinterprets and integrates previous findings. New predictions are made about the functioning of passionate love in relationships by hypothesizing a self-regulating, intimacy-seeking system that produces passionate love as its outcome. A self-regulation model proposed by Carver and Scheier in 1998 is the template on which this model is based.

scholarly journals Pipeline Compressor Redesign With the Consideration of Both Noise and Performance

2000 ◽  
Author(s):  
Yuri I. Biba ◽  
Zheji Liu ◽  
D. Lee Hill
Keyword(s):  
High Efficiency ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Design Parameters ◽  
Original Design ◽  
Tonal Noise ◽  
Experimental Performance ◽  
Expected Performance ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

A complete effort to redesign the aerodynamic characteristics of a single-stage pipeline compressor is presented. The components addressed are the impeller, diffuser region, and the volute. The innovation of this effort stems from the simultaneous inclusion of both the noise and aerodynamic performance as primary design parameters. The final detailed flange-to-flange analysis of the new components clearly shows that the operating range is extended and the tonal noise driven by the impeller is reduced. This is accomplished without sacrificing the existing high efficiency of the baseline machine. The body of the design effort uses both Computational Fluid Dynamics (CFD) and vibro-acoustics technology. The predictions are anchored by using the flange-to-flange analysis of the original design and its experimental performance data. By calculating delta corrections and assuming that these deltas are approximately the same for the new design, the expected performance is extrapolated.

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