Experimental and numerical investigation of interactions between above and below ground drainage systems

2013 ◽  
Vol 67 (3) ◽  
pp. 535-542 ◽  
Author(s):  
Slobodan Djordjević ◽  
Adrian J. Saul ◽  
Gavin R. Tabor ◽  
John Blanksby ◽  
Istvan Galambos ◽  
...  
Keyword(s):  
Numerical Investigation ◽  
Urban Areas ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Sewer Pipes ◽  
Drainage Systems ◽  
Flow Features ◽  
Below Ground ◽  
Set Up ◽  
Flood Flow

This paper presents the results of the experimental and numerical investigation of interactions between surface flood flow in urban areas and the flow in below ground drainage systems (sewer pipes and manholes). An experimental rig has been set up at the Water Engineering Laboratory at the University of Sheffield. It consists of a full scale gully structure with inlet grating, which connects the 8 m2 surface area with the pipe underneath that can function as an outfall and is also further connected to a tank so that it can come under surcharging conditions and cause outflow from the gully. A three-dimensional CFD (Computational Fluid Dynamics) model has been set up to investigate the hydraulic performance of this type of gully inlet during the interactions between surface flood flow and surcharged pipe flow. Preliminary results show that the numerical model can replicate various complex 3D flow features observed in laboratory conditions. This agreement is overall better in the case of water entering the gully than for the outflow conditions. The influence of the surface transverse slope on flow characteristics has been demonstrated. It is shown that re-circulation zones can form downstream from the gully. The number and size of these zones is influenced by the transverse terrain slope.

scholarly journals Numerical Investigation of Liquid–Liquid Mixing in Modified T Mixer with 3D Obstacles

2021 ◽  
pp. 25-32
Author(s):  
Md. Readul Mahmud
Keyword(s):  
Numerical Investigation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Channel Length ◽  
Navier Stokes ◽  
Mixing Efficiency ◽  
Mixing Performance ◽  
Wide Range

The fluids inside passive micromixers are laminar in nature and mixing depends primarily on diffusion. Hence mixing efficiency is generally low, and requires a long channel length and longtime compare to active mixers. Various designs of complex channel structures with/without obstacles and three-dimensional geometries have been investigated in the past to obtain an efficient mixing in passive mixers. This work presents a design of a modified T mixer. To enhance the mixing performance, circular and hexagonal obstacles are introduced inside the modified T mixer. Numerical investigation on mixing and flow characteristics in microchannels is carried out using the computational fluid dynamics (CFD) software ANSYS 15. Mixing in the channels has been analyzed by using Navier–Stokes equations with water-water for a wide range of the Reynolds numbers from 1 to 500. The results show that the modified T mixer with circular obstacles has far better mixing performance than the modified T mixer without obstacles. The reason is that fluids' path length becomes longer due to the presence of obstacles which gives fluids more time to diffuse. For all cases, the modified T mixer with circular obstacle yields the best mixing efficiency (more than 60%) at all examined Reynolds numbers. It is also clear that efficiency increase with axial length. Efficiency can be simply improved by adding extra mixing units to provide adequate mixing. The value of the pressure drop is the lowest for the modified T mixer because there is no obstacle inside the channel. Modified T mixer and modified T mixer with circular obstacle have the lowest and highest mixing cost, respectively. Therefore, the current design of modified T with circular obstacles can act as an effective and simple passive mixing device for various micromixing applications.

Numerical Analysis of the Wave Topping Unit for Small Turbojet

2010 ◽  
Author(s):  
Janusz Piechna ◽  
Rafael Cerpa ◽  
Staniszewski Marcin ◽  
Pezhman Akbari ◽  
Norbert Mu¨ller
Keyword(s):  
Numerical Analysis ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Wave Rotor ◽  
High Rotational Speed ◽  
Machine Performance ◽  
Flow Features ◽  
The Common ◽  
Analysis Models

The paper is focused on the numerical analysis of a wave topping unit used in a small turbojet engine. The analysis focuses on a four-port reverse flow (RF) wave rotor. The special feature of the considered wave rotor is its very high rotational speed. The wave rotor is connected directly with the common shaft between compressor and turbine, thus, the effects of Coriolis accelerations become important. In this study, first a one-dimensional model is used to estimate geometry of the wave rotor and port timings. Then, multi-dimensional analysis models are employed to predict the different flow characteristics inside the wave rotor channels. Three-dimensional flow features that reduce machine performance and influence rotor blade and duct wall thermal loads are identified.

Three-dimensional simulation and experimental investigation of three-dimensional printed guiding devices on lattice-apron compact spinning

2020 ◽  
pp. 004051752098258
Author(s):  
Malik YH Saty ◽  
Nicholus Tayari Akankwasa ◽  
Jun Wang
Keyword(s):  
Experimental Investigation ◽  
Air Flow ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Yarn Properties ◽  
3D Printed ◽  
Dimensional Simulation ◽  
Compact Spinning ◽  
Set Up

The compact spinning system with a lattice apron utilizes air-flow dynamics to condense fibers in a bunch and enhance the yarn properties. One of the main challenges with this method is the lack of a comprehensive understanding of the air-flow field's effect in the condensing zone. This work presents a numerical and experimental investigation of the effects of three-dimensional (3D) printed guiding devices on the air-flow characteristics and yarn properties. Firstly, the 3D numerical model of the compact spinning system was set up based on the compact spinning machine geometrical dimensions. Secondly, different 3D prototypes were developed, simulated, and analyzed using computational fluid dynamics based on ANSYS software. The prototypes (A-type, B-type, and C-type), selected according to the simulation results, were then 3D printed to enable further experimental investigation. Air-flow analysis results in the air-suction flume area exhibiting a very high negative pressure, and the centerline zone was characterized by high velocity. Experimental results revealed that the three yarns spun with guiding devices had better strength, hairiness, and evenness than those spun without a guiding device. The model developed can be further improved and utilized for commercial purposes and is anticipated to improve compact spun yarn properties significantly.

scholarly journals Flow Bifurcation at a Longitudinal Training Dam: Effects on Local Morphology

2018 ◽  
Vol 40 ◽  
pp. 05020 ◽  
Author(s):  
Timo de Ruijsscher ◽  
Suleyman Naqshband ◽  
Ton Hoitink
Keyword(s):  
Three Dimensional ◽  
Laser Scanner ◽  
Flow Characteristics ◽  
Side Channel ◽  
Physical Mechanisms ◽  
Mobile Bed ◽  
First Results ◽  
Acoustic Doppler Velocimetry ◽  
Sill Height ◽  
Set Up

Longitudinal training dams (LTDs) have been built over a length of 10 km in the Dutch River Waal as an alternative to groyne fields, splitting the river in a fairway and a bank-connected side channel in the inner bend. Here, we study the physical mechanisms governing the three-dimensional flow and its effect on local morphology at the flow divide using a mobile bed physical model of an LTD, centred around a side channel intake. In line with previous experiments, polystyrene granules are used as a lightweight sediment that allows to achieve dynamic similarity between the model and the prototype. An Acoustic Doppler Velocimetry (ADV) profiler is used to monitor the flow characteristics, whereas a line laser scanner set-up is used to measure the morphological imprint of the flow near the bifurcation point. To study the dependence of the results on the sill height at the side channel intake, different forms and heights of the sill are used. First results show striking similarities with measurements from the field pilot in the Waal River, as well as larger sedimentation in the side channel for a uniform low sill compared to a downstream increasing sill height.

An Efficient 3D CFD Model for the Analysis of the Flow Field Around Darrieus Rotors

2013 ◽  
Author(s):  
Marco Torresi ◽  
Bernardo Fortunato ◽  
Sergio Mario Camporeale
Keyword(s):  
Flow Field ◽  
Urban Areas ◽  
Wind Farm ◽  
Numerical Technique ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Vertical Axis ◽  
Great Capacity ◽  
Model Efficiency

An efficient numerical technique has been developed in order to investigate flow characteristics and global performance of Darrieus rotors. The interest for this kind of vertical axis wind turbines arises from their great capacity for integration within urban areas and for distributed generation. The proposed methodology is based on the solution of the steady three-dimensional governing equations, by means of a robust commercial CFD code. Since the effect of the turbine blades on the flow field is simulated through the introduction of momentum sources in the porous shell representing the volume swept by the turbine blades, any expensive refinement of the grid, near the rotor, is avoided. This approach dramatically reduces the computational costs, with respect to conventional unsteady flow simulations. The model efficiency enables the simulation of the flow field around Darrieus rotors considering complex and realistic computational domains, for instance when these turbines are clustered within a wind farm or placed inside urban areas. The methodology is validated by reproducing the performance of the Sandia 17-meter Darrieus rotor with approximate troposkien shape. Comparisons with other codes are also presented in order to highlight the advantages of the proposed method.

Flow Characteristics Within and Downstream of Spherical and Cylindrical Dimple on a Flat Plate at Low Reynolds Numbers

2004 ◽  
Author(s):  
A. Khalatov ◽  
A. Byerley ◽  
D. Ochoa ◽  
Seong-Ki Min
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Flow Patterns ◽  
Flow Features ◽  
Laminar And Turbulent Flow ◽  
Low Reynolds ◽  
Oscillation Frequencies

A comprehensive experimental study has been performed in the U.S. Air Force Academy water tunnel to obtain a better understanding of the complicated flow patterns in shallow dimple configurations (h/D ≤ 0.1), including single cylindrical and spherical dimples, as well as single spanwise rows of dimples. The flow patterns, in-dimple separation zone extent, and bulk flow oscillation frequencies have been measured at low Reynolds number conditions. Three different single dimples and two single rows of dimples have been tested over a range of Reynolds numbers ReD of 3,170 to 23,590 including laminar and turbulent flow patterns downstream of a dimple. To visualize the fine flow features, five different colors of dye were injected through five cylindrical ports machined at locations upstream and inside the dimples. The measured results revealed unsteady and three-dimensional flow features inside and downstream of the dimple. The Reynolds number, dimple shape and the presence of adjacent dimples all play important roles in determining the nature of the flow pattern formation. Some preliminary conclusions regarding the laminar-turbulent flow transition after a dimple are presented.

Numerical investigation of flow in the liner of a model reverse-flow gas turbine combustor

2009 ◽  
Vol 223 (8) ◽  
pp. 1083-1090 ◽  
Author(s):  
M H Shojaeefard ◽  
K Ariafar ◽  
K Goudarzi
Keyword(s):  
Numerical Investigation ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Reverse Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Simple Algorithm ◽  
Staggered Grid ◽  
Gas Turbine Combustor ◽  
Model Studies

Designing a combustion chamber for a gas turbine engine requires expensive tests with many iterations. A numerical analysis can be employed to reduce the number of design iterations by providing an insight into the characteristics of the flow. This present article describes a three-dimensional numerical investigation of flow inside a model reverse-flow gas turbine combustor. In this computational work the entire model including the swirler has been selected for better accuracy. A finite volume non-staggered grid approach has been used and the pressure—velocity coupling is resolved using the SIMPLE algorithm. Comparisons are made between the standard k—ɛ turbulence model and the Reynolds stress turbulence model. Studies are performed to assess the velocity and pressure distributions at different locations in the combustor liner as well as the flow split through various holes on the liner surface. Overall, the predicted flow characteristics are found to be in reasonable agreement with the available experimental data.

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