Numerical Investigation of a Hydropower Tunnel: Estimating Localised Head-Loss Using the Manning Equation

The fluid dynamics within a water tunnel is investigated numerically using a RANS approach with the k- ε turbulence model. The computational model is based on a laser scan of a hydropower tunnel located in Gävunda, Sweden. The tunnel has a typical height of 6.9 m and a width of 7.2 m. While the average cross-sectional shape of the tunnel is smooth the local deviations are significant, where some roughness elements may be in the size of 5 m implying a large variation of the hydraulic radius. The results indicate that the Manning equation can successfully be used to study the localised pressure variations by taking into account the varying hydraulic radius and cross-sectional area of the tunnel. This indicates a dominant effect of the tunnel roughness in connection with the flow, which has the potential to be used in the future evaluation of tunnel durability. ANSYS-CFX was used for the simulations along with ICEM-CFD for building the mesh.

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Simulasi Perancangan Drainase Muka Tanah pada Bandar Udara Achmad Yani Semarang Sebagai Salah Satu Usaha Pencegahan Banjir

WARTA ARDHIA ◽

10.25104/wa.v39i4.127.305-316 ◽

2013 ◽

Vol 39 (4) ◽

pp. 305-316

Author(s):

Ataline Muliasari ◽

Lupi Wahyuningsih

Keyword(s):

Surface Water ◽

Cross Section ◽

Land Surface ◽

Drainage Channel ◽

Water Drainage ◽

Hydraulic Radius ◽

Channel Depth ◽

Cross Sectional ◽

Surface Drainage ◽

Sectional Shape

Drainage is defined as surface water drainage, either by gravity or by pump which aims to prevent inundation, maintain and lower the water level im order to avoid the amount of water. Ahmad Yani Airport has a poor drainage systems. Furthermore, land subsidence in Semarang area potential for experiencing flooding when the rainy season with a fairly high rainfall. Based on the results of processing the data showed that it is needed the land surface drainage channel with a cross-sectional shape of a trapezium. When the width of the base of the cross section is 3 meters , then the required channel depth is 3.9 meters with a hydraulic radius is 0.82-meter, and hydraulic depth is 3.05 meters. Drainase didefinisikan sebagai pembuangan air permukaan, baik secara gravitasi maupun dengan pompa yang bertujuan untuk mencegah terjadinya genangan, menjaga dan menurunkan permukaan air sehingga genangan air dapat dihindarkan. Bandar Udara Ahmad Yani dengan kondisi sistem drainase yang kurang baik dan penurunan permukaan tanah di wilayah Semarang, maka bila musim penghujan tiba dengan curah hujan yang cukup tinggi selalu berpotensi untuk mengalami banjir. Berdasarkan hasil pengolahan data juga didapatkan hasil bahwa untuk menyesuaikan antara curah hujan di wilayah Semarang dengan luas area Bandar udara Achmad Yani diperlukan saluran drainase muka tanah berupa saluran dengan bentuk penampang trapezium. Bila lebar dasar dari penampang trapezim tersebut adalah 3 meter, maka diperlukan saluran sedalam 3,9 meter dengan Jari-jari hydraulic 0,82 meter, dan kedalaman hydraulic 3,05 meter.

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Effect of Groove Shape on Head Loss and Filtration Performance of Disc Filters

Water ◽

10.3390/w13121683 ◽

2021 ◽

Vol 13 (12) ◽

pp. 1683

Author(s):

Sang-ik Lee ◽

Jin-Yong Choi ◽

Won Choi

Keyword(s):

Performance Test ◽

Filter Design ◽

Head Loss ◽

Sectional Area ◽

Cross Sectional ◽

Loss Analysis ◽

Groove Shape ◽

Filtration Performance ◽

Sectional Shape ◽

The Relationship

To analyze the effect of a groove cross-sectional shape on disc filters, a head loss analysis and filtration performance test were conducted using disc filters with different groove shapes (semi-elliptical- and trapezoidal-shaped grooves). Furthermore, the groove shapes were analyzed using field emission scanning electron microscopy and the relationship between flow rate and head loss was derived from the head loss test. Even if the filters were designed with the same mesh standard, the sectional areas of the grooves were different depending on the shape. Therefore, the head loss was compared under the condition that the grooves have the same sectional area by applying the relationship between head loss and sectional area, and a smaller head loss was observed in the semi-elliptical-shaped groove. Additionally, the semi-elliptical-groove-shaped disc filter was evaluated to sufficiently filter the soil particles corresponding to the 120 mesh standard. Therefore, an optimum disc filter can be designed by considering the cross-sectional shape of the disc groove to reduce energy consumption and provide stable filtration. The elliptical groove shape, which is hydraulically advantageous, is preferred for the disc filter design.

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Simulation of local head loss of drip-irrigation tape with integrated in-line emitters as a function of cross section

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2020184-15767 ◽

2020 ◽

Vol 18 (4) ◽

pp. e0210

Author(s):

Yalin Wang ◽

Xueliang Ju ◽

Shijiang Zhu ◽

Meng Li

Keyword(s):

Cross Section ◽

Drip Irrigation ◽

Low Pressure ◽

Head Loss ◽

Three Gorges ◽

Cross Sectional ◽

Water Conservancy ◽

The Cross ◽

Sectional Shape ◽

The Relationship

Aim of study: To investigate how the cross section of a drip-irrigation tape affects local head loss.Area of study: The work was carried out in the laboratory of Irrigation hydraulics, College of Water Conservancy and Environment, Three Gorges University, Yichang, Hubei province.Material and methods: Tapes with six different wall thicknesses were studied experimentally to determine the relationship between cross-section deformation, wall thickness, and pressure. Based on the experimental results, we determined the factors that influence local head loss in drip-irrigation tapes by numerical simulation and dimensional analysis.Main results: The cross-sectional shape of the drip-irrigation tape varied with pressure: under low pressure, the cross section was nearly elliptical. The cross-sectional shape of the tape strongly influenced the local head loss, which was inversely proportional to the 0.867th power of the flattening coefficient of the drip irrigation tape. We expressed the local head loss of a drip-irrigation tape equipped with integrated in-line emitters by considering the deformation of the cross section. Under the conditions used in this study, when the cross section is circular, the ratio of local head loss to frictional head loss was about 10% but, when the cross section is elliptical, this ratio increased to 15%.Research highlights: The shape of the cross section of a drip-irrigation tape is nearly elliptical under low pressure. Local head loss is inversely proportional to the 0.867th power of that is the flatting coefficient of the drip-irrigation tape. Local head loss is about 1.5 times for elliptical tape than circular tape.

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The Characteristic Behavior of Finite Length Line Sources of Heat in a Crossflow

Journal of Heat Transfer ◽

10.1115/1.2910384 ◽

1990 ◽

Vol 112 (2) ◽

pp. 349-355 ◽

Cited By ~ 1

Author(s):

P. R. Slawson ◽

G. J. Hitchman ◽

L. E. Hawker

Keyword(s):

Cross Section ◽

Finite Length ◽

Empirical Relation ◽

Integral Model ◽

Water Tunnel ◽

Growth Enhancement ◽

Single Source ◽

Trajectory Data ◽

Cross Sectional ◽

Sectional Shape

A modified simple integral model for plume behavior from finite length line sources of heat and momentum is presented that identifies observed trends in plume trajectory data. Experiments on several finite length line sources of heat and momentum in the form of elevated (rows of stacks) and surface (slot) releases were conducted in a water tunnel. Plume behavior was documented through detailed temperature measurements of the plume cross section and by photographing the dyed plume. Results indicate the nature of any plume trajectory and growth enhancement and confirm the empirical relation for the liftoff distance for a buoyant surface plume given by Meroney (1979). In addition to the liftoff distance, the shape of the plume contact zone was measured and related to various regions of plume trajectory and cross-sectional shape. Plume trajectories from elevated line releases are adequately predicted by standard single source formulations; however, plume cross-sectional area is significantly overpredicted

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On the cross-sectional shape of the cellulose crystallites in the tunicate Halocynthia papillosa

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160388 ◽

1990 ◽

Vol 48 (3) ◽

pp. 566-567

Author(s):

J.-F. Revol ◽

Y. Van Daele ◽

F. Gaill

Keyword(s):

Contrast Imaging ◽

Animal Kingdom ◽

Bright Field ◽

Field Mode ◽

Cross Sectional ◽

Ultrathin Sections ◽

The Cross ◽

Sectional Shape ◽

Valonia Ventricosa ◽

C Nmr

The only form of cellulose which could unequivocally be ascribed to the animal kingdom is the tunicin that occurs in the tests of the tunicates. Recently, high-resolution solid-state l3C NMR revealed that tunicin belongs to the Iβ form of cellulose as opposed to the Iα form found in Valonia and bacterial celluloses. The high perfection of the tunicin crystallites led us to study its crosssectional shape and to compare it with the shape of those in Valonia ventricosa (V.v.), the goal being to relate the cross-section of cellulose crystallites with the two allomorphs Iα and Iβ.In the present work the source of tunicin was the test of the ascidian Halocvnthia papillosa (H.p.). Diffraction contrast imaging in the bright field mode was applied on ultrathin sections of the V.v. cell wall and H.p. test with cellulose crystallites perpendicular to the plane of the sections. The electron microscope, a Philips 400T, was operated at 120 kV in a low intensity beam condition.

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Automated 3D measurement of fiber cross section morphology in handsheets

Nordic Pulp & Paper Research Journal ◽

10.3183/npprj-2012-27-02-p264-269 ◽

2012 ◽

Vol 27 (2) ◽

pp. 264-269 ◽

Cited By ~ 9

Author(s):

Christian Lorbach ◽

Ulrich Hirn ◽

Johannes Kritzinger ◽

Wolfgang Bauer

Keyword(s):

Image Analysis ◽

Cross Section ◽

Cross Sections ◽

Image Plane ◽

3D Measurement ◽

Cross Sectional ◽

Fiber Cross Section ◽

Fiber Wall ◽

Sectional Shape ◽

Cross Section Geometry

Abstract We present a method for 3D measurement of fiber cross sectional morphology from handsheets. An automated procedure is used to acquire 3D datasets of fiber cross sectional images using an automated microtome and light microscopy. The fiber cross section geometry is extracted using digital image analysis. Simple sample preparation and highly automated image acquisition and image analysis are providing an efficient tool to analyze large samples. It is demonstrated that if fibers are tilted towards the image plane the images of fiber cross sections are always larger than the true fiber cross section geometry. In our analysis the tilting angles of the fibers to the image plane are measured. The resulting fiber cross sectional images are distorted to compensate the error due to fiber tilt, restoring the true fiber cross sectional shape. We use an approximated correction, the paper provides error estimates of the approximation. Measurement results for fiber wall thickness, fiber coarseness and fiber collapse are presented for one hardwood and one softwood pulp.

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Study of Correctly Expanded Sonic Jet with Air Tabs

International Journal of Turbo and Jet Engines ◽

10.1515/tjj-2020-0005 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Arun Prasad R ◽

Thanigaiarasu S ◽

Sembaruthi M ◽

Rathakrishnan E

Keyword(s):

Numerical Study ◽

Cross Sectional ◽

Potential Core ◽

Convergent Nozzle ◽

Jet Mixing ◽

Pressure Profiles ◽

Constant Diameter ◽

Sonic Jet ◽

Sectional Shape ◽

Length Reduction

AbstractThe present numerical study is to understand the effect of air tabs located at the exit of a convergent nozzle on the spreading and mixing characteristics of correctly expanded sonic primary jet. Air tabs used in this study are two secondary jets issuing from constant diameter tubes located diametrically opposite at the periphery of the primary nozzle exit, normal to the primary jet. Two air tabs of Mach numbers 1.0 to 1.4, in steps of 0.1 are considered in this study. The mixing modification caused by air tabs are analysed by considering the mixing of uncontrolled (free) primary jet as a reference. Substantial enhancement in jet mixing is achieved with Mach 1.4 air tabs, which results in 80 % potential core length reduction. The total pressure profiles taken on the plane (YZ) normal to the primary jet axis, at various locations along the primary jet centreline revealed the modification of the jet cross sectional shape by air tabs. The stream-wise vortices and bifurcation of the primary jet caused by air tabs are found to be the mechanism behind the enhanced jet mixing.

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Experimental investigation and optimization on field shaper structure parameters in magnetic pulse welding

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/09544054211014846 ◽

2021 ◽

pp. 095440542110148

Author(s):

Yingzi Chen ◽

Zhiyuan Yang ◽

Wenxiong Peng ◽

Huaiqing Zhang

Keyword(s):

Magnetic Field ◽

High Speed ◽

Light Metal ◽

Magnetic Pulse ◽

Cross Sectional ◽

Magnetic Pulse Welding ◽

Pulse Welding ◽

Sectional Shape ◽

Welding System ◽

The Magnetic Field

Magnetic pulse welding is a high-speed welding technology, which is suitable for welding light metal materials. In the magnetic pulse welding system, the field shaper can increase the service life of the coil and contribute to concentrating the magnetic field in the welding area. Therefore, optimizing the structure of the field shaper can effectively improve the efficiency of the system. This paper analyzed the influence of cross-sectional shape and inner angle of the field shaper on the ability of concentrating magnetic field via COMSOL software. The structural strength of various field shapers was also analyzed in ABAQUS. Simulation results show that the inner edge of the field shaper directly affects the deformation and welding effect of the tube. So, a new shape of field shaper was proposed and the experimental results prove that the new field shaper has better performance than the conventional field shaper.

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