scholarly journals INVESTIGATION INTO THE HYDRODYNAMIC PROCESSES OF FITTING CONNECTIONS FOR DETERMINING PRESSURE LOSSES OF TRANSPORT HYDRAULIC DRIVE

Transport ◽  
2020 ◽  
Vol 35 (1) ◽  
pp. 108-120
Author(s):  
Mykola Karpenko ◽  
Marijonas Bogdevičius
Keyword(s):  
Fluid Flow ◽  
Experimental Research ◽  
Stokes Equations ◽  
Hydraulic Drive ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Pressure Losses ◽  
Physical Experiments ◽  
Hydrodynamic Processes

The article presents the findings of theoretical and experimental research on hydraulic processes occurring in the hydraulic drives of transport machines. The paper analyses the influence of hydrodynamic processes on the flow characteristics of fluid considering different hydraulic fitting connections. The performed analysis is based on numerical simulations using Navier–Stokes equations for the velocity field. The dynamics of fluid flow in the hydraulic system has been investigated taking into account the main parameters like system flow rate in the range of 5 to 100 L/min, the diameter of the pipeline making 1/2” and fitting standards DKOL, ORFS, BSP and JIS. As a result, pressure drop, power losses, resistance and flow coefficients at different fitting connections have been obtained. The article compares the provided results with the findings given employing the calculation method for the standard of equivalent length fitting. To simulate fluid flow, a mesh independence study and turbulence calculations have been performed. Simulation results have been examined conducting physical experiments on measuring pressure losses. Each experimental research includes three measurements of connections bearing in mind each fitting standard.

scholarly journals Research on high-pressure hose with repairing fitting and influence on energy parameter of the hydraulic drive

2021 ◽  
Vol 24 (1) ◽  
pp. 25-32
Author(s):  
Mykola Karpenko ◽  
Olegas Prentkovskis ◽  
Šarūnas Šukevičius
Keyword(s):  
High Pressure ◽  
Fluid Flow ◽  
Stokes Equations ◽  
Hydraulic Drive ◽  
Energy Parameter ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Pressure Drops ◽  
Pressure Losses ◽  
Technical Maintenance

Reliability and maintenance analysis of transport machines hydraulic drives, basically focused to power units: pumps, cylinders etc., without taking in to account junction elements. Therefore, this paper proposes a research analysis on high-pressure hoses and junctions during technical maintenance. Comparative analysis of fluid behavior and energy efficiency inside non-repaired and repaired high-pressure hoses is presented in this research. Theoretical and experimental research results for hydraulic processes inside high-pressure hose is based on the numerical simulations using Navier–Stokes equations and experimental measurement of fluid flow pressure inside high-pressure hoses. Research of fluid flow dynamics in the hydraulic system was made with main assumptions: system flow rate in the range from 5 to 100 l/min, diameter of the hoses and repairing fitting are 3/8". The pressure drops, power losses, flow coefficients at non-repaired and after maintenance hose was obtained as a result. Simulation results were verified by running physical experiments to measure the pressure losses.

INFLUENCE OF FLAT WALL DIFFUSER WALL OSCILLATION ON HYDRODYNAMIC PARAMETERS OF VISCOUS FLUID FLOW

2019 ◽  
Vol 9 (1) ◽  
pp. 119-125
Author(s):  
Evgeny A. KRESTIN
Keyword(s):  
Fluid Flow ◽  
Viscous Fluid ◽  
Stokes Equations ◽  
Hydraulic Drive ◽  
Polar Coordinates ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Viscous Fluid Flow ◽  
Moving Wall ◽  
Hydrodynamic Parameters

In order to reduce the energy consumption, increase the reliability of the hydraulic drive of construction machines and mechanisms, studies of the hydrodynamic parameters of the viscous fluid flow in a flat diffuser during the oscillation of one of the walls of the channel are carried out. Navier-Stokes equations together with the continuity equation are used to construct velocity and pressure fields. The problem is solved in polar coordinates with boundary conditions. The General solution of the problem, which corresponds to the self-similar boundary condition on the moving wall, is obtained. The radial velocity profile has sections of forward and reverse currents and is a standing wave along the angular coordinate. The forces acting on the movable and stationary walls of the diffuser are determined.

Fluid Flow Characteristics Around a Pair of Diamond-Shaped Cylinders in Side-by-Side and Tandem Arrangements

2011 ◽  
Author(s):  
Shuichi Torii ◽  
Noritugu Ueda ◽  
Zijie Lin
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Time History ◽  
Flow Patterns ◽  
Separation Distance ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Gap Spacing

The present study deals with unsteady laminar fluid flow phenomena around a pair of diamond-shaped cylinders in free stream. Emphasis is placed on the effects of the Reynolds number, Re, and the ratio of cylinder separation distance to length of diamond-shaped cylinder, s/d, on the flow patterns in side-by-side and tandem arrangements. The Navier-Stokes equations are discretized using finite difference method to determine the time history of velocity vector in the flow field. The Reynolds numbers, Re, is ranged from 30 to 300 and gap spacing, s/d, is varied from 0.0 to 2.5 for side-by-side and 0.0 to 5.0 for tandem, respectively. The results are compared with the experimental results with the aid of flow visualization method. The study discloses that (i) the generations of Karman vortex streets behind the diamond-shaped cylinders are intensified with an increase in the Reynolds number, (ii) the categorized flow patterns in the wake region of the diamond-shaped islands are affected by s/d, and (iii) the vortex shedding frequency in the wake of diamond-shaped cylinders depends on both the gap spacing and the formation of the vortices.

A numerical study of inkjet refilling

2004 ◽  
Vol 218 (12) ◽  
pp. 1481-1497
Author(s):  
K-S Yang ◽  
I-Y Chen ◽  
C-C Wang
Keyword(s):  
Fluid Flow ◽  
Bubble Growth ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Channel Design ◽  
Navier Stokes Equations ◽  
Inkjet Printer

A numerical study is conducted to examine the flow characteristics of the inkjet printer head with special attention made to the refilling process. By solving the full set of three-dimensional transient Navier-Stokes equations and considering the process of bubble growth and collapse as a movable membrane, the fluid flow inside the channel and the ejected droplet from the nozzle can be modelled. The calculated results indicate that the single refilling channel design provides the fastest refilling rate but also reveals pronounced flow surge/overshot phenomena. By using a double refilling channel design, the flow surge/overshot phenomenon can be reduced considerably owing to the imposed friction. Moreover, the flooding phenomenon is much less pronounced. However, placing an additional cylinder obstacle in the single filling channel will not reduce the flow surge/overshot phenomenon.

Fluid flow over and through a regular bundle of rigid fibres

2016 ◽  
Vol 792 ◽  
pp. 5-35 ◽  
Author(s):  
Giuseppe A. Zampogna ◽  
Alessandro Bottaro
Keyword(s):  
Porous Medium ◽  
Fluid Flow ◽  
Flow Field ◽  
Stokes Equations ◽  
Transversely Isotropic ◽  
Navier Stokes ◽  
Leading Order ◽  
Macroscopic Scale ◽  
Navier Stokes Equations ◽  
Homogenized Model

The interaction between a fluid flow and a transversely isotropic porous medium is described. A homogenized model is used to treat the flow field in the porous region, and different interface conditions, needed to match solutions at the boundary between the pure fluid and the porous regions, are evaluated. Two problems in different flow regimes (laminar and turbulent) are considered to validate the system, which includes inertia in the leading-order equations for the permeability tensor through a Oseen approximation. The components of the permeability, which characterize microscopically the porous medium and determine the flow field at the macroscopic scale, are reasonably well estimated by the theory, both in the laminar and the turbulent case. This is demonstrated by comparing the model’s results to both experimental measurements and direct numerical simulations of the Navier–Stokes equations which resolve the flow also through the pores of the medium.

Modelling Turbulent Flow in Deformable Highly Porous Seabed and Structures

2018 ◽  
Author(s):  
Hisham Elsafti ◽  
Hocine Oumeraci
Keyword(s):  
Porous Media ◽  
Transient Flow ◽  
Stokes Equations ◽  
Pore Fluid ◽  
Navier Stokes ◽  
Model Parameters ◽  
Navier Stokes Equations ◽  
Deformable Porous Media ◽  
Physical Experiments ◽  
Fluid Coupling

In this study, the fully-coupled and fully-dynamic Biot governing equations in the open-source geotechFoam solver are extended to account for pore fluid viscous stresses. Additionally, turbulent pore fluid flow in deformable porous media is modeled by means of the conventional eddy viscosity concept without the need to resolve all turbulence scales. A new approach is presented to account for porous media resistance to flow (solid-to-fluid coupling) by means of an effective viscosity, which accounts for tortuosity, grain shape and local turbulences induced by flow through porous media. The new model is compared to an implemented extended Darcy-Forchheimer model in the Navier-Stokes equations, which accounts for laminar, transitional, turbulent and transient flow regimes. Further, to account for skeleton deformation, the porosity and other model parameters are updated with regard to strain of geomaterials. The presented model is calibrated by means of available results of physical experiments of unidirectional and oscillatory flows.

Numerical simulation of the stalled flow within a vaned centrifugal pump

2004 ◽  
Vol 218 (4) ◽  
pp. 425-435 ◽  
Author(s):  
K M Guleren ◽  
A Pinarbasi
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
High Speed ◽  
Stokes Equations ◽  
Reverse Flow ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Navier Stokes Equations ◽  
Low Pass

The main goal of the present work is to analyse the numerical simulation of a centrifugal pump by solving Navier-Stokes equations, coupled with the ‘standard k-∊’ turbulence model. The pump consists of an impeller having five curved blades with nine diffuser vanes. The shaft rotates at 890r/min. Flow characteristics are assumed to be stalled in the appropriate region of flowrate levels of 1.31-2.861/s. Numerical analysis techniques are performed on a commercial FLUENT package program assuming steady, incompressible flow conditions with decreasing flowrate. Under stall conditions the flow in the diffuser passage alternates between outward jetting when the low-pass-filtered pressure is high to a reverse flow when the filtered pressure is low. Being below design conditions, there is a consistent high-speed leakage flow in the gap between the impeller and the diffuser from the exit side of the diffuser to the beginning of the volute. Separation of this leakage flow from the diffuser vane causes the onset of stall. As the flowrate decreases both the magnitude of the leakage within the vaneless part of the pump and reverse flow within a stalled diffuser passage increase. As this occurs, the stall-cell size extends from one to two diffuser passages. Comparisons are made with experimental data and show good agreement.

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