Multiphase Flow in a Liquid-Ring Vacuum Pump

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Ashutosh Pandey ◽  
Sajid Khan ◽  
Rick Dekker ◽  
Tom I-P. Shih
Keyword(s):  
Multiphase Flow ◽  
Rotational Speed ◽  
Computational Study ◽  
Critical Role ◽  
Expansion Ratio ◽  
Navier Stokes ◽  
Compression And Expansion ◽  
Acceleration And Deceleration ◽  
The Difference ◽  
Liquid Ring

Abstract A computational study based on unsteady Reynolds-averaged Navier–Stokes that resolves the gas–liquid interface was performed to examine the unsteady multiphase flow in a liquid-ring pump as a function of its inlet pressure (10, 40, and 80 kPa) and its impeller's rotational speed (1150, 1450, and 1750 rpm). Results obtained show the shape of the liquid ring to play a critical role in creating the expansion ratio needed to draw air into the pump and the compression ratio needed to expel air out of the pump. The dominant processes that determine the shape of the liquid ring was found to be the centrifugal force from rotation, the acceleration and deceleration due to the difference in pressure at the pump's inlet and outlet, and the eccentricity of the impeller relative to the pump's housing. Results are presented to show how the rotational speed of the impeller and the pressure at the pump's inlet affect the nature of the multiphase flow in the pump as well as the pump's effectiveness in creating a vacuum. The effects of heat transfer on the gas phase during the compression and expansion processes were found to be approximated well by polytropic processes. This computational study was validated by comparing computed with measured volumetric flowrates ingested through the suction port and the torque exerted on the pump's impeller.

Experimental and Numerical Investigation on Overall Performance of a Radial Inflow Turbine for 100kW Mircoturbine

2007 ◽  
Author(s):  
Qinghua Deng ◽  
Jiufang Niu ◽  
Jingru Mao ◽  
Zhenping Feng
Keyword(s):  
Numerical Simulation ◽  
Rotational Speed ◽  
Incidence Angle ◽  
Expansion Ratio ◽  
Navier Stokes ◽  
Inlet Temperature ◽  
Velocity Change ◽  
Exit Velocity ◽  
Overall Performance ◽  
Radial Inflow Turbine

This paper describes a study on overall performance of the radial inflow turbine for a 100kW microturbine by means of experimental and numerical investigations. All tests are performed with a turbine inlet temperature of 773K and an atmospheric exit pressure, and the rotor rotational speed is ranged from 20000 to 50000 rpm. In addition, the overall performance and the energy loss characteristics for each component of the radial inflow turbine are investigated by 3D Reynolds-averaged Navier-Stokes solutions. The volute, the whole passages of nozzle vanes and rotor, and the exhaust diffuser are meshed with multi-block structured grid. The results of numerical simulation agreed well, as a whole, with that of the experiment both for stage mass flow rate and stage total-static efficiency, which achieved the desired requirements of the design. Based on the results of numerical simulation, the losses of components and exit velocity are analyzed respectively at the off-design conditions. At turbine design point, the losses of volute, nozzle, rotor, exit velocity and exhaust diffuser are about 1.5%, 25%, 43%, 19.5%, 11% of the total loss, respectively, and the rotor incidence angle is basically at optimized value of −23.6°. The losses of rotor and exit velocity change significantly when stage expansion ratio or the rotational speed of rotor altered. In addition, the loss of volute is relative small in the nozzled radial inflow turbine, and then the effect of volute can be neglected in the process of thermal aerodynamic design.

Investigation of the Shock Wave Formation and Intensity in Wave Rotor

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
Peiqi Liu ◽  
Xiang Li ◽  
Xinyu Liu ◽  
Jun Yang ◽  
Mingyu Feng ◽  
...  
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Rotational Speed ◽  
Expansion Ratio ◽  
Wave Intensity ◽  
Dynamics Simulation ◽  
Wave Rotor ◽  
Compression Waves ◽  
The Difference ◽  
The One

Abstract Actual formation and intensity of shock wave generated during gradual opening and closure between each port and passages of wave rotor are studied by means of experiment and computational fluid dynamics simulation. The results show that the intensity of shock wave increases with the distance from high-pressure inlet, and the reason for the variation tendency is the superposition of compression waves. By changing the rotational speed and the expansion ratio, the shock wave intensity can be adjusted, but the position where the intensity reaches maximum stays constant basically and keeps the distance near 300 mm from high-pressure inlet. Comparing with the one-dimensional simplification result, the actual intensity of shock wave is lower. The difference between the fact and simplification increases with the rotational speed and expansion ratio. The internal mechanism has been analyzed from the aspect of intake mass. Then, the maximum shock wave intensity is found approximately linear to the intake mass of each rotor passage in each cycle.

Experimental and Numerical Analysis of a Motorcycle Air Intake System Aerodynamics and Performance

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
M. A. Abd Halim ◽  
N. A. R. Nik Mohd ◽  
M. N. Mohd Nasir ◽  
M. N. Dahalan
Keyword(s):  
Combustion Process ◽  
Three Dimensional ◽  
Engine Performance ◽  
Internal Flow ◽  
Rapid Expansion ◽  
Navier Stokes ◽  
Turbulent Fluctuation ◽  
Ansys Fluent ◽  
Induction System ◽  
Acceleration And Deceleration

Induction system or also known as the breathing system is a sub-component of the internal combustion system that supplies clean air for the combustion process. A good design of the induction system would be able to supply the air with adequate pressure, temperature and density for the combustion process to optimizing the engine performance. The induction system has an internal flow problem with a geometry that has rapid expansion or diverging and converging sections that may lead to sudden acceleration and deceleration of flow, flow separation and cause excessive turbulent fluctuation in the system. The aerodynamic performance of these induction systems influences the pressure drop effect and thus the engine performance. Therefore, in this work, the aerodynamics of motorcycle induction systems is to be investigated for a range of Cubic Feet per Minute (CFM). A three-dimensional simulation of the flow inside a generic 4-stroke motorcycle airbox were done using Reynolds-Averaged Navier Stokes (RANS) Computational Fluid Dynamics (CFD) solver in ANSYS Fluent version 11. The simulation results are validated by an experimental study performed using a flow bench. The study shows that the difference of the validation is 1.54% in average at the total pressure outlet. A potential improvement to the system have been observed and can be done to suit motorsports applications.

Explaining the magnetism of gold

2017 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Formation Enthalpy ◽  
Gold Atom ◽  
Orbital Energy ◽  
Knudsen Effusion ◽  
Energy Diagram ◽  
Unpaired Electrons ◽  
The Difference ◽  
Good Agreement

<p>In the present work, a computational study is performed in order to clarify the possible magnetic nature of gold. For such purpose, gas phase Au<sub>2</sub> (zero charge) is modelled, in order to calculate its gas phase formation enthalpy. The calculated values were compared with the experimental value obtained by means of Knudsen effusion mass spectrometric studies [5]. Based on the obtained formation enthalpy values for Au<sub>2</sub>, the compound with two unpaired electrons is the most probable one. The calculated ionization energy of modelled Au<sub>2</sub> with two unpaired electrons is 8.94 eV and with zero unpaired electrons, 11.42 eV. The difference (11.42-8.94 = 2.48 eV = 239.29 kJmol<sup>-1</sup>), is in very good agreement with the experimental value of 226.2 ± 0.5 kJmol<sup>-1</sup> to the Au-Au bond<sup>7</sup>. So, as expected, in the specie with none unpaired electrons, the two 6s<sup>1</sup> (one of each gold atom) are paired, forming a chemical bond with bond order 1. On the other hand, in Au<sub>2</sub> with two unpaired electrons, the s-d hybridization prevails, because the relativistic contributions. A molecular orbital energy diagram for gas phase Au<sub>2</sub> is proposed, explaining its paramagnetism (and, by extension, the paramagnetism of gold clusters and nanoparticles).</p>

Computational Study of the Multiphase Flow and Performance of Hydrocyclones: Effects of Cyclone Size and Spigot Diameter

2013 ◽  
Vol 52 (45) ◽  
pp. 16019-16031 ◽  
Author(s):  
M. Ghodrat ◽  
S. B. Kuang ◽  
A. B. Yu ◽  
A. Vince ◽  
G. D. Barnett ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Computational Study ◽  
And Performance

Effects of Waves on the Wake of a Surface-Piercing Flat Plate: Experiment and Theory

1993 ◽  
Vol 37 (02) ◽  
pp. 102-118
Author(s):  
F. Stern ◽  
J. E. Choi ◽  
W. S. Hwang
Keyword(s):  
Streamwise Velocity ◽  
Navier Stokes ◽  
Pressure Gradients ◽  
Alternating Direction ◽  
Displacement Thickness ◽  
Acceleration And Deceleration ◽  
Streamwise Velocity Component ◽  
Model Geometry ◽  
Layer Region ◽  
Wave Induced

Results are presented from a towing-tank experiment conducted in order to document the effects of waves on the wake of a surface-piercing body. A unique, simple model geometry is utilized which makes it possible to isolate and identify the most important features of the wave-induced effects. Measurements were made for three wave-steepness conditions: zero, medium, and large. The effects of the waves for the latter two conditions are shown to be significant. In particular, the variations of the external-flow pressure gradients cause acceleration and deceleration phases of the streamwise velocity component and alternating direction of the crossflow, which results in large oscillations of the displacement thickness and wake centerplane velocities as compared to the zero-steepness condition. Remarkably, the wake displays a greater response, that is, a bias with regard to favorable as compared to adverse pressure gradients. The measurements are compared and close agreement is demonstrated with results from Reynolds-averaged Navier-Stokes calculations. Additional calculations are presented, including laminar-flow results, which aid in explicating the characteristics of the near and intermediate wake, the periodic nature of the far wake, and wave-induced separation. Previously, experimental and computational results were presented for the boundary-layer region.

Migrating Progenitor Cells Derived From Injured Cartilage Surface Respond to Damage-Associated Molecular Patterns

Cartilage ◽  
2021 ◽  
pp. 194760352110495
Author(s):  
Lei Ding ◽  
Cheng Zhou ◽  
Hongjun Zheng ◽  
Quanming Wang ◽  
Haiyan Song ◽  
...  
Keyword(s):  
Articular Cartilage ◽  
Progenitor Cells ◽  
Quantitative Polymerase Chain Reaction ◽  
Critical Role ◽  
Cartilage Degeneration ◽  
Expression Levels ◽  
Chondrogenic Progenitor Cells ◽  
The Difference ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

Objective: To delineate the response of migrating chondrogenic progenitor cells (CPCs) that arose from the surface of mechanically injured articular cartilage to proinflammatory damage-associated-molecular-patterns (DAMPs). Design: Bovine CPCs and non-CPC chondrocytes isolated from either impacted or scratched articular cartilage were studied. Those 2 types of cells were treated with mitochondrial DAMPs (MTDs; 10 nM fMLF and 10 µg/mL CpG DNA), or 10 nM HMGB1, or 10 ng/mL IL-1b for 24 hours. At the end of experiments, conditioned media and cell lysates were collected for analysis of expression levels of matrix metalloproteinases (MMPs), chemokines, and cytokines that are associated with cartilage degeneration with Western blotting and quantitative polymerase chain reaction. The difference of expression levels was compared by Welch’s t-test. Results: Our data indicated that HMGB1 and MTDs remarkably upregulated pro-MMP-13 expression in CPCs. Compared with non-CPCs, CPCs expressed significantly more baseline mRNAs of MMP-13, CXCL12, and IL-6. MTDs greatly increased the expression of MMP-13 and IL-6 in CPCs by over 100-fold ( P < 0.001). MTDs also significantly increased IL-8 expression in CPCs to a similar extent ( P < 0.001). However, when IL-1b was present, CPCs expressed less MMP-3 and active MMP-13 proteins as well as less CCL2 and IL-6 than did non-CPCs. Conclusions: We concluded that CPCs were more sensitive than non-CPCs in response to DAMPs, especially MTDs. The proinflammatory nature of CPCs implied their critical role in the early phase of posttraumatic osteoarthritis development.

scholarly journals Dialysate Calcium Levels: Do They Matter?

2018 ◽  
Vol 47 (1-3) ◽  
pp. 230-235 ◽  
Author(s):  
Frank M. van der Sande ◽  
Karlien J.A. ter Meulen ◽  
Peter Kotanko ◽  
Jeroen P. Kooman
Keyword(s):  
Vitamin D ◽  
Critical Role ◽  
Essential Element ◽  
Vascular Pathology ◽  
Phosphate Binders ◽  
Multiple Parameters ◽  
Vitamin D Analogues ◽  
Endocrine Disturbances ◽  
Increased Risk ◽  
The Difference

Background: Calcium (Ca) is an essential element that plays a critical role in many biological processes. In dialysis patients, the regulation of Ca balance is highly complex, given the absence of kidney function, endocrine disturbances and the use of drugs such as phosphate binders, vitamin D analogues, and calcimimetics. Also, the use of different dialysate Ca (DCa) baths has profound effect on Ca balance, which depends both on the difference between the Ca concentration in the bath and the serum of the patients, as on the ultrafiltration volume. Summary: The choice of DCa may have important short- and long-term consequences. While lower DCa (especially < 2.5 mEq/L) concentrations have been associated with an increased risk of sudden cardiac death in observational studies, DCa in the higher ranges (3.0 mEq/L and above) may contribute to vascular pathology. Intra-dialytic hemodynamics may also be affected by the choice of DCa. In general, lower DCa concentrations are associated with an increase, and higher DCa concentrations with a decrease in parathyroid hormone (PTH) levels. Preliminary data has suggested that a DCa of 2.75 mEq/L may help in obtaining a net zero intradialytic Ca balance in individual patients, but clinical experience is still limited. Key Message: The optimal Ca balance depends on multiple parameters including blood Ca levels, PTH and the use of phosphate binders and vitamin D analogues, as well as on the risk of hemodynamic stability and cardiac arrhythmias. Therefore, DCa prescription should be individualised. A DCa of 2.75 mEq/L may be useful adjunct for dialysis providers.

scholarly journals Thermochemical Nonequilibrium in Rapidly Expanding Flows of High-Temperature Air

1997 ◽  
Vol 52 (4) ◽  
pp. 358-368 ◽  
Author(s):  
Michio Nishida ◽  
Masashi Matsumotob
Keyword(s):  
High Temperature ◽  
Vibrational Energy ◽  
Stokes Equations ◽  
Computational Study ◽  
Mass Conservation ◽  
Navier Stokes ◽  
Tvd Scheme ◽  
Governing Equations ◽  
Navier Stokes Equations ◽  
Free Jet

Abstract • This paper describes a computational study of the thermal and chemical nonequilibrium occuring in a rapidly expanding flow of high-temperature air transported as a free jet from an orifice into low-density stationary air. Translational, rotational, vibrational and electron temperatures are treated separately, and in particular the vibrational temperatures are individually treated; a multi-vibrational temperature model is adopted. The governing equations are axisymmetric Navier-Stokes equations coupled with species vibrational energy, electron energy and species mass conservation equations. These equations are numerically solved, using the second order upwind TVD scheme of the Harten-Yee type. The calculations were carried out for two different orifice temperatures and also two different orifice diameters to investigate the effects of such parameters on the structure of a nonequilibrium free jet.

scholarly journals Comparison and analysis of calculation of Bridge backwater based on Mike21 hydrodynamic model

2021 ◽  
Vol 233 ◽  
pp. 03043
Author(s):  
Jiang Chuan Liu ◽  
Zhu Qiu Hu ◽  
Mao Yuan Zhu
Keyword(s):  
Theoretical Basis ◽  
Impact Analysis ◽  
Navier Stokes ◽  
Efficiency Coefficient ◽  
Navier Stokes Equation ◽  
The Real ◽  
Comparison And Analysis ◽  
Simulation Results ◽  
The Difference ◽  
Local Water

The construction of bridges and other structures across the river will affect the flood discharge capacity and local water potential of the river.Based on navier-Stokes equation of MIKE21FM hydrodynamic module, this paper carries out two-dimensional numerical simulation of part of Shixi River. By optimizing the grid near the piers to reduce the difference brought by the terrain generalized grid of the real river, it simulates and analyzes the length of the curve of yong-high and Yong-water under different flood frequencies,the Nash-Sutcliffe efficiency coefficient and relative error analysis are used to verify the rationality of the results. The simulation results can accurately reflect the real changes of river water level, It provides a theoretical basis for flood impact analysis.

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