Numerical Simulation on Internal Flows of Reducing Cross

2014 ◽  
Vol 945-949 ◽  
pp. 980-986
Author(s):  
Jian Ping Yuan ◽  
Wen Ting Sun ◽  
Yin Luo ◽  
Bang Lun Zhou
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Branch Pipe ◽  
Three Dimensional ◽  
Uniform Flow ◽  
Hydraulic Loss ◽  
Steady Flows ◽  
Internal Flows ◽  
Inlet Velocity ◽  
Main Pipe

In order to study the internal flows and hydraulic loss of reducing cross, numerical simulation was carried out on a horizontally installed reducing cross. Three schemes of pipe diameters were studied. The time-averaged N-S equations of three-dimensional steady flows in the reducing pipe were calculated by CFX 14.5 based on the standard - two equation turbulence model together with standard wall function. The results show that the higher the inlet velocity, the hydraulic loss become larger when the split ratios are same for the reducing cross. With the uniform inlet velocities the higher the inlet velocity, the quicker the increasing rate of the hydraulic loss in main pipe, as well as the branch pipe. The integral change rules of hydraulic loss are similar with the condition of uniform flow rate inflow when the flow patterns at inlet are uniform. But with the same spilt ratio, the hydraulic loss of uniform velocity inflow is markedly less than that of uniform flow rate inflow in both main pipe and branch pipe. The bigger the differences of the diameters between the main pipe and the branch pipe, the larger the hydraulic loss of the branch pipe.

G0500-1-3 Three-Dimensional Numerical Simulation of a Spherical Particle Cluster in Uniform Flow

2010 ◽  
Vol 2010.2 (0) ◽  
pp. 257-258
Author(s):  
Kenji NAKASHIMA ◽  
Yuuki JOHNO ◽  
Takahiro YAMAUCHI ◽  
Shingo KAnAZAWA
Keyword(s):  
Numerical Simulation ◽  
Spherical Particle ◽  
Three Dimensional ◽  
Uniform Flow ◽  
Particle Cluster

scholarly journals Three-dimensional numerical simulation of stepped dropshaft with different step shapes

2020 ◽  
Author(s):  
Jingkang Sun ◽  
Shangtuo Qian ◽  
Hui Xu ◽  
Xiaosheng Wang ◽  
Jiangang Feng
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Standing Wave ◽  
Flow Rate ◽  
Effective Means ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Deep Tunnel ◽  
Rate Distribution ◽  
Tunnel System

Abstract The deep tunnel system is increasingly used worldwide for stormwater conveyance and storage, providing a robust and effective means of preventing urban waterlogging. In the system, the dropshaft with the function of conveying stormwater to the deep tunnels underground, often runs under conditions of high falling head and large discharge. Based on the standard stepped dropshaft, a blade-shaped stepped dropshaft was proposed in order to control the potential standing wave and improve discharge capacity. Its hydraulic characteristics in respect of flow pattern, flow rate distribution, time-averaged pressure and energy dissipation were investigated by numerical simulation. Compared with the standard stepped dropshaft, the blade-shaped stepped dropshaft generated a more uniform flow rate distribution in the radial direction, therefore effectively decreasing the height of the standing wave near the external wall. The negative pressure areas that easily existed on the vertical wall of steps were well controlled. The energy dissipation of the blade-shaped stepped dropshaft was as high as that of the standard stepped dropshaft. Therefore, the blade-shaped stepped dropshaft could be a preferable design for the deep tunnel system.

Thermal Fatigue Analysis at a Mixing Tee by a Fluid-Structural Simulation

2011 ◽  
Author(s):  
Masayuki Kamaya ◽  
Yoichi Utanohara ◽  
Akira Nakamura
Keyword(s):  
Thermal Stress ◽  
Fatigue Damage ◽  
Cold Water ◽  
Axial Stress ◽  
Branch Pipe ◽  
Three Dimensional ◽  
Dynamics Simulation ◽  
Cold Spot ◽  
Current Case ◽  
Main Pipe

In this study, the thermal stress at a mixing tee was calculated by the finite element method using temperature transients obtained by a fluid dynamics simulation. The simulation target was an experiment for a mixing tee, in which cold water flowed into the main pipe from a branch pipe. The cold water flowed along the main pipe wall and caused a cold spot, at which the membrane stress was relatively large. Based on the evaluated thermal stress, the magnitude of the fatigue damage was assessed according to the linear damage accumulation rule and the rain-flow procedure. Precise distributions of the thermal stress and fatigue damage could be identified. Relatively large axial stress occurred downstream from the branch pipe due to the cold spot. The position of the cold spot changed slowly in the circumferential direction, and this was the main cause of the fatigue damage. In the thermal stress analysis for fatigue damage assessment, it was concluded that the detailed three-dimensional structural analysis was not required. Namely, for the current case, a one-dimensional simplified analysis could be used for evaluating the fatigue damage without adopting the stress enhancement factor Kt quoted in the JSME guideline.

scholarly journals Numerical Simulation of Full-Scale Three-Dimensional Fluid Flow in an Oscillating Reactor

2021 ◽  
Vol 9 ◽  
Author(s):  
Houjun Gong ◽  
Mengqi Wu
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Flow Field ◽  
Flow Rate ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Full Scale ◽  
Variation Patterns ◽  
Oscillating Motion ◽  
Resistance Coefficients

Marine reactors are subjected to additional motions due to ocean conditions. These additional motions will cause large fluctuation of flow rate and change the coolant flow field, making the system unstable. Therefore, in order to understand the effect of oscillating motion on the flow characteristics, a numerical simulation of fluid flow is carried out based on a full-scale three-dimensional oscillating marine reactor. In this study, the resistance coefficients of the lattice, rod buddle and steam generator are fitted, and the distribution of flow rate, velocity as well as pressure in different regions is investigated through the standard model. After additional oscillation is introduced, the flow field in an oscillating reactor is presented and the effect of oscillating angle and elevation on the flow rate is investigated. Results show that the oscillating motion can greatly change the flow field in the reactor; most of the coolant circulates in the downcommer and lower head with only a small amount of coolant entering the core; the flow fluctuation period is consistent with the oscillating period, and the flow variation patterns under different oscillating conditions are basically the same; since the flow amplitude is related to oscillating speed, the amplitude of flow rate rises when decreasing the maximum oscillating angle; the oscillating elevation has little effect on the flow rate.

The effects of temperature-dependent viscosity on flow in a cooled channel with application to basaltic fissure eruptions

1995 ◽  
Vol 305 ◽  
pp. 239-261 ◽  
Author(s):  
Jonathan J. Wylie ◽  
John R. Lister
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Three Dimensional ◽  
Finite Amplitude ◽  
Theoretical Description ◽  
Steady Flows ◽  
Two Dimensional ◽  
Temperature Dependent Viscosity ◽  
Dependent Viscosity ◽  
Averaged Model

A theoretical description is given of pressure-driven viscous flow of an initially hot fluid through a planar channel with cold walls. The viscosity of the fluid is assumed to be a function only of its temperature. If the viscosity variations caused by the cooling of the fluid are sufficiently large then the relationship between the pressure drop and the flow rate is non-monotonic and there can be more than one steady flow for a given pressure drop. The linear stability of steady flows to two-dimensional and three-dimensional disturbances is calculated. The region of instability to two-dimensional disturbances corresponds exactly to those flows in which an increase in flow rate leads to a decrease in pressure drop. At higher viscosity contrasts some flows are most unstable to three-dimensional (fingering) instabilities analogous, but not identical, to Saffman-Taylor fingering. A cross-channel-averaged model is derived and used to investigate the finite-amplitude evolution.

Numerical Simulation and Experimental Study on Hydraulic Performance of Centrifugal Pump's Impeller Based on FINE

2013 ◽  
Vol 444-445 ◽  
pp. 390-394
Author(s):  
Yong Shang ◽  
Xiao Bing Liu ◽  
Xue Jun Yu
Keyword(s):  
Numerical Simulation ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Hydraulic Performance ◽  
Test Results ◽  
Turbulent Model ◽  
Three Dimensional Flow ◽  
Dimensional Flow

By using the FINE software developed by NUMECA Company, the hydraulic performance of the impeller of a centrifugal pump with spatial guide vanes was numerically simulated. The S-A turbulent model was used to numerically calculate the three-dimensional flow field in the centrifugal pump under three different conditions. The flow analysis shows that the pressure gradient on the vane surface gradually reduces with the increasing of the flow rate; the position of axial vortex between vanes has nothing to do with the flow rate; the tangential flow gradient in the flow passage decreases with the increasing of the flow rate. Compared with the test results, it is obvious that this numerical simulation can accurately predicate the complicated three-dimensional flow and the hydraulic performance of the pump.

1101 Numerical Simulation of the Flow in a Branch Pipe with Three-dimensional Bending

2008 ◽  
Vol 2008.83 (0) ◽  
pp. _11-1_
Author(s):  
Tetsutaro WATANABE ◽  
Takehiko INABA ◽  
Yasutaka YAMAGUCHI
Keyword(s):  
Numerical Simulation ◽  
Branch Pipe ◽  
Three Dimensional

scholarly journals Constructal Microdevice Manifold Design With Uniform Flow Rate Distribution by Consideration of the Tree-Branching Rule of Leonardo da Vinci and Hess–Murray Rule

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Erdal Cetkin
Keyword(s):  
Pressure Distribution ◽  
Flow Rate ◽  
Da Vinci ◽  
Uniform Flow ◽  
Leonardo Da Vinci ◽  
Flow Uniformity ◽  
Inlet Velocity ◽  
Rate Distribution ◽  
Constructal Design ◽  
Branching Rule

In this paper, we show how the design of a microdevice manifold should be tapered for uniform flow rate distribution. The designs based on the tree-branching rule of Leonardo da Vinci and the Hess–Murray rule were considered in addition to the constructal design. Both da Vinci and Hess–Murray designs are insensitive to the inlet velocity, and they provide better flow uniformity than the base (not tapered) design. However, the results of this paper uncover that not only pressure drop but also velocity distribution in the microdevice play an integral role in the flow uniformity. Therefore, an iterative approach was adopted with five degrees-of-freedom (inclined wall positions) and one constraint (constant distribution channel thickness) in order to uncover the constructal design which conforms the uniform flow rate distribution. In addition, the effect of slenderness of the microchannels (Svelteness) and inlet velocity on the flow rate distribution to the microchannels has been documented. This paper also uncovers that the design of a manifold should be designed with not only the consideration of pressure distribution but also dynamic pressure distribution especially for non-Svelte microdevices.

scholarly journals NUMERICAL SIMULATION OF WATER CIRCULATION IN A CYLINDRICAL HORIZONTAL THERMAL TANK

2009 ◽  
Vol 8 (1) ◽  
pp. 72
Author(s):  
D. L. Savicki ◽  
H. A. Vielmo
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Significant Variation ◽  
Thermal Stratification ◽  
Numerical Study ◽  
Three Dimensional ◽  
Velocity Fields ◽  
Water Circulation ◽  
Numerical Code ◽  
Temperature And Velocity Fields

It is carried out a numerical study of the three-dimensional temperature and velocity fields in a cylindrical horizontal thermal tank during the process of water circulation. The numerical simulations were made using an academic Finite Volumes numerical code. This simulation considers that the thermal tank is connected to solar collectors. So, in the tank, the inlet jet temperature is higher than those inside the tank. This study aims to investigate the influence of the inlet jet on thermal stratification. The results show that for the mass flow rate studied, there is no significant variation on thermal stratification.

Sign in / Sign up

Export Citation Format

Share Document