A CFD Investigation of a 2D Balanced Vane Pump Focusing on Leakage Flows and Multiphase Flow Characteristics

Vane pumps are often applied in automatic transmission systems of vehicles. Future applications require the oil pumps to be more efficient and to be able to handle multiphase flow pumping situations to a certain extend. To fulfill these requirements, efficient development tools are needed. Therefore, a less demanding computational 2D model of a fixed-type balanced vane pump was derived and numerically analyzed with the commercial computational fluid dynamics (CFD) software ANSYS CFX. The meshing of the rotating parts was done with TwinMesh, using a moving mesh approach. At first, a mesh convergence study was performed. It was shown that the resolution of the radial clearances in particular had a significant influence on the predicted leakages and the volumetric efficiency. The leakage was further investigated concerning the dependence on rotational speed and delivery pressure. In the next step, multiphase flows were considered. In a first setup, vapor cavitation was analyzed and the influence of the alignment of the suction ports on its onset was derived. In a second setup, the influence of different inlet volume fractions of free air was evaluated. The employed multiphase modeling approach was presented and a sensitivity analysis on modeling parameters was performed. Overall, it was shown that free air in the suction ports changed the pumping characteristic of the vane pump significantly. Pressure and flow ripple increased, and the volumetric efficiency and the mean power demand decreased significantly with an increasing inlet volume fraction.

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A CFD-Based Comparison of Different Positive Displacement Pumps for Application in Future Automatic Transmission Systems

Energies ◽

10.3390/en14092501 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2501

Author(s):

Thomas Lobsinger ◽

Timm Hieronymus ◽

Hubert Schwarze ◽

Gunther Brenner

Keyword(s):

Experimental Data ◽

Multiphase Flow ◽

Mass Flow ◽

Automatic Transmission ◽

Three Dimensional ◽

Numerical Results ◽

Gear Pump ◽

Vane Pump ◽

Flow Ripple ◽

Free Air

The efficiency requirements for hydraulic pumps applied in automatic transmissions in future generations of automobiles will increase continuously. In addition, the pumps must be able to cope with multiphase flows to a certain extent. Given this background, a balanced vane pump (BVP), an internal gear pump (IGP) and a three-dimensional geared tumbling multi chamber (TMC) pump are analyzed and compared by a computational fluid dynamics (CFD) approach with ANSYS CFX and TwinMesh. Furthermore, test bench measurements are conducted to obtain experimental data to validate the numerical results. The obtained numerical results show a reasonable agreement with the experimental data. In the first CFD setup, the conveying characteristics of the pumps with pure oil regarding volumetric efficiencies, cavitation onset and pressure ripple are compared. Both the IGP and the BVP show high volumetric efficiencies and low pressure ripples whereas the TMC shows a weaker performance regarding these objectives. In the second CFD setup, an oil-bubbly air multiphase flow with different inlet volume fractions (IGVF) is investigated. It can be shown that free air changes the pumping characteristics significantly by increasing pressure and mass flow ripple and diminishing the volumetric efficiency as well as the required driving torque. The compression ratios of the pumps appear to be an important parameter that determines how the multiphase flow is handled regarding pressure and mass flow ripple. Overall, the BVP and the IGP show both a similar strong performance with and without free air. In the current development state, the TMC pump shows an inferior performance because of its lower compression ratio and therefore needs further optimization.

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A practical approach for analysis of leakage flow characteristics in hydraulic pumps

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406212456933 ◽

2012 ◽

Vol 227 (5) ◽

pp. 980-991 ◽

Cited By ~ 8

Author(s):

Yoshiharu Inaguma

Keyword(s):

Mathematical Model ◽

Automatic Transmission ◽

Flow Characteristics ◽

Operating Conditions ◽

Practical Approach ◽

Leakage Flow ◽

Vane Pump ◽

Delivery Pressure ◽

Gear Pumps ◽

Internal Gear

This article presents a practical approach to leakage flow analysing for various types of hydraulic pumps. In this study, the influence of pump-operating conditions such as operating pressures, pump speeds and oil temperature on the leakage flow characteristics is investigated and a mathematical model to calculate the leakage flow is proposed. Currently, an external gear, an internal gear or a vane pump is commonly used for an automatic transmission. These pumps have their own leakage flow characteristics, which depend not only on pump-operating conditions but also on structures and dimensions of the pumps. For various pumps having different constructions, the delivery pressure and the oil temperature differently affect the leakage flow characteristics and especially the delivery pressure also changes the clearances causing the leakage flow. A mathematical model for the leakage flow, which takes into account a change in the thickness of clearance according to the delivery pressure, represents accurately the actual leakage flow characteristics in various pumps. Also, it clarifies the influence of the pump-operating conditions on their leakage flow characteristics. In the external and internal gear pumps, the leakage flow would not approach zero due to an existence of the orifice flow leakage almost independent of the viscosity of oil, even at an extremely low oil temperature. This leakage flow influences significantly the volumetric efficiency at a low oil temperature in the gear pumps.

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Injector Nozzle Multiphase Flow Numerical Simulation of High Pressure Common Rail System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1008-1009.1006 ◽

2014 ◽

Vol 1008-1009 ◽

pp. 1006-1010

Author(s):

Yan Hu ◽

Guo Xiu Li

Keyword(s):

Numerical Simulation ◽

High Pressure ◽

Multiphase Flow ◽

Volume Fraction ◽

Flow Characteristics ◽

Common Rail ◽

Injector Nozzle ◽

Short Period ◽

Nozzle Structure ◽

High Pressure Common Rail

The changing of injector nozzle structure will influence the combustion and emission properties in diesel engine. Three-dimensional numerical simulation of multiphase flow of mini-sac nozzles of high pressure common rail were calculated by using the computational fluid dynamics ( CFD ) method in this paper. The results shown that this method can be more accurately obtained a lot of useful information on the flow field inside the nozzle in a relatively short period of time, and it is convenient for analysis and research the influence of geometry parameters on the flow characteristics inside the nozzle. The paper also studied the influence of nozzle inlet pressure, the angle between the axis of the hole and the axis of the injector and nozzle entrance radius to the flow characteristics inside the nozzle. It also studied the distribution of internal pressure, velocity of flow, gas-phase volume fraction and turbulent kinetic energy. These studies provided a favorable basis for the design and improvement of the nozzle structure and optimize combustion system matches.

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Studies on the Hard Chrome Plating in Reciprocating Air Compressors

Volume 8A: Heat Transfer and Thermal Engineering ◽

10.1115/imece2018-86532 ◽

2018 ◽

Author(s):

Aadhithiyan Amutha Kulasekaran ◽

Anbarasu Subramanian

Keyword(s):

Power Consumption ◽

Cylinder Liner ◽

Volumetric Efficiency ◽

Working Pressure ◽

Chrome Plating ◽

Free Air ◽

Delivery Pressure ◽

Hard Chrome ◽

Experimental Values ◽

Air Compressors

This present work is to investigate the effects of chrome plating in reciprocating air compressors that result in reduction of power consumption. Reciprocating air compressors are the most commonly used compressors for domestic and industrial purposes to give required air output in terms of free air delivery, delivery temperature and maximum working pressure. This study also develops a better understanding on the effect of honing in the cylinder which reduces the surface roughness in the cylinder liner and results in greater air output. Cylinders are made of graded cast iron. The cylinder liner was honed to a thickness of about 0.26 mm and hard chrome plated to the same thickness. The honing improves the volumetric efficiency and hard chrome plating reduces the power consumption. The adequacy of this model can be verified using thermal image analysis, which includes the various temperature distribution plots around the compressor components. Further delivery temperature, actual displacement and free air delivery pressure are the parameters that conclude the deviation in actual and experimental values. Power consumption and efficiency owe for the major expenditures and maintenance for Reciprocating air compressors. This paper suggests the need of hard chrome plating to a compressor cylinder that resulted in annual power savings of about 25%. The increase in volumetric efficiency was about 20–30% from the actual conditions.

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Heat Transmission Reinforcers Induced by MHD Hybrid Nanoparticles for Water/Water-EG Flowing over a Cylinder

Coatings ◽

10.3390/coatings11060623 ◽

2021 ◽

Vol 11 (6) ◽

pp. 623

Author(s):

Firas A. Alwawi ◽

Mohammed Z. Swalmeh ◽

Amjad S. Qazaq ◽

Ruwaidiah Idris

Keyword(s):

Heat Transfer ◽

Heat Transfer Rate ◽

Transfer Rate ◽

Volume Fraction ◽

Liquid Velocity ◽

Flow Characteristics ◽

Hybrid Nanoparticles ◽

Critical Parameters ◽

Heat Transmission ◽

Constant Wall Temperature

The assumptions that form our focus in this study are water or water-ethylene glycol flowing around a horizontal cylinder, containing hybrid nanoparticles, affected by a magnetic force, and under a constant wall temperature, in addition to considering free convection. The Tiwari–Das model is employed to highlight the influence of the nanoparticles volume fraction on the flow characteristics. A numerical approximate technique called the Keller box method is implemented to obtain a solution to the physical model. The effects of some critical parameters related to heat transmission are also graphically examined and analyzed. The increase in the nanoparticle volume fraction increases the heat transfer rate and liquid velocity; the strength of the magnetic field has an adverse effect on liquid velocity, heat transfer, and skin friction. We find that cobalt nanoparticles provide more efficient support for the heat transfer rate of aluminum oxide than aluminum nanoparticles.

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Research on Cavitation of the Rotating-Sleeve Distributing Flow System Considering Different Cam Groove Profiles

Energies ◽

10.3390/en14082139 ◽

2021 ◽

Vol 14 (8) ◽

pp. 2139

Author(s):

Shanxiao Du ◽

Jichao Hong ◽

Hongxin Zhang ◽

Qinghai Zhao ◽

Tiezhu Zhang ◽

...

Keyword(s):

Volume Fraction ◽

Flow System ◽

Volumetric Efficiency ◽

Piston Pump ◽

Operating Frequency ◽

Cavitation Model ◽

Pump Chamber ◽

Orthogonal Experiments ◽

Simulation Results ◽

Further Development

Reciprocating piston pumps are widely used in various fields, such as automobiles, ships, aviation, and engineering machinery. Conventional reciprocating piston pump distributing flow (RPPDF) systems have the disadvantages of a loose structure and low volumetric efficiency, as well as affected positively by the operating frequency. In this paper, a novel rotating-sleeve distributing flow (RSDF) system is presented for bridging these drawbacks, as well as structurally improved to overcome the inoperable and challenging problems in oil intake and discharge found in the experiment. Moreover, the Singhal cavitation model specifically for the RSDF system and four-cam groove profiles (CGPs) is established. To find the most suitable CGP to reduce the RSDF’s cavitation, the cavitation of the RSDF system was investigated, combining with simulations by taking into account the gap among the rotating sleeve, the pump chamber, and experiments on four presented CGPs. Simulation results based on vapor volume fraction, cavitation ratio, and volumetric efficiency show that the linear profile’s cavitation is the weakest. Finally, the correctness of the simulation is verified through orthogonal experiments. This research is of great significance to the further development of the RSDF system; more important, it has great potential to promote the reform of the RPPDF method.

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Computational Modeling of Flow Characteristics in Three Products Hydrocyclone Screen

Processes ◽

10.3390/pr9081295 ◽

2021 ◽

Vol 9 (8) ◽

pp. 1295

Author(s):

Anghong Yu ◽

Chuanzhen Wang ◽

Haizeng Liu ◽

Md. Shakhaoath Khan

Keyword(s):

Static Pressure ◽

Cfd Simulation ◽

Volume Fraction ◽

Flow Characteristics ◽

Pressure Profile ◽

Reynolds Stress Model ◽

Grid Scheme ◽

Cylindrical Screen ◽

The Right ◽

Axial Depth

Three products hydrocyclone screen (TPHS) can be considered as the combination of a conventional hydrocyclone and a cylindrical screen. In this device, particles are separated based on size under the centrifugal classification coupling screening effect. The objective of this work is to explore the characteristics of fluid flow in TPHS using the computational fluid dynamics (CFD) simulation. The 2 million grid scheme, volume fraction model, and linear pressure–strain Reynolds stress model were utilized to generate the economical grid-independence solution. The pressure profile reveals that the distribution of static pressure was axisymmetric, and its value was reduced with the increasing axial depth. The maximum and minimum were located near the tangential inflection point of the feed inlet and the outlets, respectively. However, local asymmetry was created by the left tangential inlet and the right screen underflow outlet. Furthermore, at the same axial height, the static pressure gradually decreased along the wall to the center. Near the cylindrical screen, the pressure difference between the inside and the outside cylindrical screen dropped from positive to negative as the axial depth increased from −35 to −185 mm. Besides, TPHS shows similar distributions of turbulence intensity I, turbulence kinetic energy k, and turbulence dissipation rate ε; i.e., the values fell with the decrease in axial height. Meanwhile, from high to low, the pressure values are distributed in the feed chamber, the cylindrical screen, and conical vessel; the value inside the screen was higher than the outer value.

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Quantitative Experimental Study of SiO2-Water Nanofluids on Backward-Facing Step Flow under Low Reynolds Number

Materials Science Forum ◽

10.4028/www.scientific.net/msf.916.221 ◽

2018 ◽

Vol 916 ◽

pp. 221-225

Author(s):

Ji Zu Lv ◽

Liang Yu Li ◽

Cheng Zhi Hu ◽

Min Li Bai ◽

Sheng Nan Chang ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Reynolds Number ◽

Volume Fraction ◽

Pure Water ◽

Experimental Studies ◽

Flow Characteristics ◽

Thermal Engineering ◽

Heat Transfer Medium ◽

Step Flow

Nanofluids is an innovative study of nanotechnology applied to the traditional field of thermal engineering. It refers to the metal or non-metallic nanopowder was dispersed into water, alcohol, oil and other traditional heat transfer medium, to prepared as a new heat transfer medium with high thermal conductivity. The role of nanofluids in strengthening heat transfer has been confirmed by a large number of experimental studies. Its heat transfer mechanism is mainly divided into two aspects. On the one hand, the addition of nanoparticles enhances the thermal conductivity. On the other hand, due to the interaction between the nanoparticles and base fluid causing the changes in the flow characteristics, which is also the main factor affecting the heat transfer of nanofluids. Therefore, a intensive study on the flow characteristics of nanofluids will make the study of heat transfer more meaningful. In this experiment, the flow characteristics of SiO2-water nanofluids in two-dimensional backward step flow are quantitatively studied by PIV. The results show that under the same Reynolds number, the turbulence of nanofluids is larger than that of pure water. With the increase of nanofluids volume fraction, the flow characteristics are constantly changing. The quantitative analysis proved that the nanofluids disturbance was enhanced compared with the base liquid, which resulting in the heat transfer enhancement.

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Flow Characteristics of a Powder Lubricant in a Slider Bearing

10.1115/imece2001/fed-24914 ◽

2001 ◽

Author(s):

Manjunath Pappur ◽

M. M. Khonsari

Keyword(s):

Slip Velocity ◽

Thrust Bearing ◽

Volume Fraction ◽

Flow Characteristics ◽

Slider Bearing ◽

Systematic Development ◽

Powder Lubrication ◽

Insight Into ◽

Theory And Experiment ◽

Good Agreement

Abstract This paper deals with a systematic development of theory of powder lubrication with the appropriate formalism based on the fundamentals of fluid mechanics. The theory is capable of predicting flow velocity, fluctuation (pseudo-temperature), powder volume fraction, and slip velocity at the boundaries. An extensive set of parametric simulations covering particle size, surface roughness, volumetric flow, load and speed are performed to gain insight into the performance of a powder lubricated thrust bearing. The results of simulations are compared to the published experimental results. Good agreement between the theory and experiment attests to the capability of the model and its potential for design of powder lubricated bearings.

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