scholarly journals Viscous Loss Analysis of the Flooded Electro-Hydrostatic Actuator Motor under Laminar and Turbulent Flow States

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 975
Author(s):  
Yanpeng Li ◽  
Zongxia Jiao ◽  
Tian Yu ◽  
Yaoxing Shang
Keyword(s):  
Calculation Method ◽  
Heat Dissipation ◽  
Cfd Simulation ◽  
Viscous Friction ◽  
Lumped Parameter Model ◽  
Friction Loss ◽  
Gradient Theory ◽  
Flow State ◽  
Lumped Parameter ◽  
Viscous Loss

The electro-hydrostatic actuator (EHA) is one of the most prevalent types of power-by-wire (PBW) actuation systems. With the increase in EHA power density, using the pump’s leakage oil to cool the motor has been gradually adopted to solve the problem of excessive motor temperature. However, the viscous friction loss caused by the liquid viscosity will seriously affect the heat dissipation effect and dynamic performance of the motor. To calculate the motor viscosity loss accurately, a novel calculation method is proposed in this paper. Using the energy gradient theory, the relationship between the fluid flow state and the rotation speed is analyzed. In addition, the lumped parameter model of viscous loss is established by using the conservation of momentum theory and computational fluid dynamics (CFD) simulation. A test rig is designed to test the viscous friction loss for various rotation speeds, and the test results show a good agreement with the theoretical analysis. The present results demonstrate the effectiveness of the lumped parameter model and provide a better calculation method for wet motor viscosity loss calculation.

Lumped Parameter Description of Thermoviscous Acoustics in Tubes with Equilateral Triangular Cross-Sections

2019 ◽  
Vol 105 (6) ◽  
pp. 1283-1285
Author(s):  
René Christensen
Keyword(s):  
Boundary Layer ◽  
Transmission Line ◽  
Cross Section ◽  
Cross Sections ◽  
Circular Cross Section ◽  
Lumped Parameter Model ◽  
Entire Cross Section ◽  
Lumped Parameter ◽  
Viscous Loss ◽  
Lumped Parameters

An accurate acoustic model of a tube in the millimeter or sub-millimeter size should include the losses that occur due to viscosity and thermal conduction, collectively termed thermoviscous losses. These losses are prominent in a boundary layer near the tube walls. Under the assumption that the boundary layer is thick compared to a characteristic geometry length, such as the radius for a circular cross-section, and fills out the entire cross-section, the tube can be described via a lumped parameter model. The lumped parameters have been known for several decades for a tube with circular cross-section, but the equilateral triangular tube has only been investigated in terms of transmission line parameters. The lumped parameters have here been established for the equilateral triangular tube as a truncated series solution of the transmission line parameters. One result observed is that the lumped parameter model for a triangular tube has 38% more viscous loss than a circular tube for a given area.

Lumped Parameter Modeling for Microfluidic Networks for Realizing Reconfigurable Nano-Optics Architectures

2010 ◽  
Author(s):  
Seok-Won Kang ◽  
Hector J. De Los Santos ◽  
Debjyoti Banerjee
Keyword(s):  
Cross Sections ◽  
Photonic Band Gap ◽  
Flow Behavior ◽  
Viscous Friction ◽  
Lumped Parameter Model ◽  
Working Fluid ◽  
Graphic User Interface ◽  
Network Architectures ◽  
Lumped Parameter ◽  
Filling Time

The geometry of a microchannel (or nanochannel) has a significant effect on pressure drop due to viscous friction. In this study, we investigate the flow behavior in microfluidic network architectures where the flow occurs from a straight square main channel to tributary channels. The flow phenomena are studied for various geometries such as circular, hexagonal, rectangular, rhombohedra, square, and triangular cross-sections. We calculate the filling time of microchannels by tracking the meniscus position in capillary driven flows. For this calculation, we implement a lumped parameter model based on electrical analogies between flow resistance and viscous friction factor. The simulation of this model is conducted using MATLAB GUI (Graphic User Interface) and it enables an end-user to perform parametric studies such as the effect of hydraulic diameter, length, geometry, number of tributary channels, and properties of the working fluid. The results of simulation are verified via Computational Fluid Dynamics (CFD) simulations (VOF method). The motivation of this study is to develop relevant design tools for predicting the flow behavior in different reconfigurable microfluidic/nanofluidic network architectures for the realization of programmable photonic band gap crystals (PBC).

Numerical Modeling of a Helical External Gear Pump With Continuous-Contact Gear Profile: A Comparison Between a Lumped-Parameter and a 3D CFD Approach of Simulation

2018 ◽  
Author(s):  
Xinran Zhao ◽  
Andrea Vacca ◽  
Sujan Dhar
Keyword(s):  
Cfd Simulation ◽  
Good Description ◽  
Helical Gear ◽  
Lumped Parameter Model ◽  
Fluid Power ◽  
Gear Pump ◽  
Continuous Contact ◽  
Positive Displacement ◽  
Lumped Parameter ◽  
Flow Features

The concept of continuous-contact helical gear pumps (CCHGP) has been proposed and successfully commercialized in the recent past. Thanks to the continuous-contact rotor profile design and to the helical gear structure, this design eliminates the kinematic flow oscillation. This has important implications on the fluid borne noise generation, which is considered as one of the major sources of noise emissions and mechanical vibrations for positive displacement machines. Although the commercial success of the CCHGP concept, there is very little published studies about the underling physics at the basis of the functioning of this type of design. This is mostly due to the complexity of the fluid domain that characterize the functioning of CCHGP units. In this paper, a transient 3D CFD study is conducted for a reference CCHGP unit for high-pressure (up to 200 bar) fluid power applications. The results of the 3D CFD simulation are compared with those given by a lumped-parameter model developed at the Maha Fluid Power Research Center of Purdue University (USA), which was previously validated against experimental results. The results show how with a proper discretization of the fluid domain the CFD simulation approach can be used for the case of helical CCHGP units. Both models provide a good description of the main features of operation of the unit. The lumped parameter model is quicker, thus suitable for fast optimization studies. However, the CFD results not only can be used to support the main assumptions done on the lumped parameter model, they also permit to gain further insight on the operation of the CCHGP unit, particularly with respect to the flow features of the meshing process.

scholarly journals Multiphase CFD Simulation of Solid Propellant Combustion in a Small Gun Chamber

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Ahmed Bougamra ◽  
Huilin Lu
Keyword(s):  
Cfd Simulation ◽  
Numerical Study ◽  
Lumped Parameter Model ◽  
Charge Weight ◽  
Maximum Pressure ◽  
Multiphase Model ◽  
Velocity Increase ◽  
Muzzle Velocity ◽  
Lumped Parameter ◽  
The Impact

The interior ballistics simulations in 9 mm small gun chamber were conducted by implementing the process into the mixture multiphase model of Fluent V6.3 platform. The pressure of the combustion chamber, the velocity, and the travel of the projectile were investigated. The performance of the process, namely, the maximum pressure, the muzzle velocity, and the duration of the process was assessed. The calculation method is validated by the comparison of the numerical simulations results in the small gun with practical tests, and with lumped-parameter model results. In the current numerical study, both the characteristics and the performance of the interior ballistic process were reasonably predicted compared with the practical tests results. The impact of the weight charge on the interior ballistic performances was investigated. It has been found that the maximum pressure and the muzzle velocity increase with the increase of the charge weight.

scholarly journals Engineering Procedure for Positive Displacement Pump Performance Analysis Based on 1D and 3D CFD Commercial Codes

2017 ◽  
Author(s):  
Aleksandar Josifovic ◽  
Matthew Stickland ◽  
Aldo Iannetti ◽  
Jonathan Corney
Keyword(s):  
Cfd Simulation ◽  
Numerical Data ◽  
Experimental Tests ◽  
Input Function ◽  
Lumped Parameter Model ◽  
Cfd Analysis ◽  
Positive Displacement ◽  
Lumped Parameter ◽  
Time Required ◽  
Parameter Approach

A numerical analysis methodology, which demonstrates how a 1D pipework simulation can be enhanced with the results of a 3D CFD simulation of key components, is used to estimate the performance of multi-cylinder Positive Displacement pumps. The procedure uses of a 1-D lumped fluid dynamics model whose accuracy was improved by incorporating CFD analysis of the PD pump valves. The application describes how valve loss co-efficient resulting from CFD analysis was utilised by the lumped parameter model as an input function. The results suggest that the combination of the CFD and lumped parameter approach exceeds the limitations found by Iannetti [1] in modelling the interaction between the pump chambers of a multi-cylinder pump as the simplified lumped parameter approach makes the entire multi-cylinder model affordable in terms of computational power and time required. The results obtained are validated by means of experimental tests the results of which are presented together with the numerical data. An example of the capability of the procedure developed and the support it is able to provide to designers is also presented.

scholarly journals CFD Simulation of a Post-Compensated Load Sensing Directional Control Valve

2021 ◽  
Vol 312 ◽  
pp. 05002
Author(s):  
Paola Fresia ◽  
Massimo Rundo
Keyword(s):  
Pressure Drop ◽  
Cfd Simulation ◽  
Control Valve ◽  
Design Tool ◽  
Lumped Parameter Model ◽  
Cfd Model ◽  
Load Sensing ◽  
Directional Control ◽  
Lumped Parameter ◽  
Directional Control Valve

The paper presents the CFD model of a load sensing directional control valve. The model was validated experimentally in terms of pressure drop and flow force at different positions of the spool. The spool position was imposed manually by means of a micrometric screw and a load cell was used for measuring the flow force. The CFD model was developed with the CAD-embedded tool FloEFD®. The model has been proved to be very reliable in estimating the pressure drop, moreover quite good results were obtained also in the evaluation of the flow force. The CFD simulations were used to tune the coefficients of a lumped parameter model of the valve, so that such a model can be efficiently used for the simulation of an entire hydraulic circuit. Moreover, the CFD model has been used as design tool for attenuating the detrimental effect of the flow force. In particular, the width of the land upstream of the metering edge has an influence on the resultant force on the spool. If was found that it is possible to significantly reduce the flow force at maximum opening with a relatively small increment of the pressure drop across the valve.

scholarly journals A Distributed Lumped Parameter Model of Blood Flow

2020 ◽  
Vol 48 (12) ◽  
pp. 2870-2886
Author(s):  
Mehran Mirramezani ◽  
Shawn C. Shadden
Keyword(s):  
Blood Flow ◽  
Lumped Parameter Model ◽  
Lumped Parameter
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