ENE-306 Open Channel Hydraulics Class 3 rd Teaching Scheme: (1 hour lecture + 1 hour tutorial + 2 hours practical) per week Credits: 4

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1 ENE-06 Open Channel Hdraulis Class rd Teahing Sheme: ( hour leture + hour tutorial + hours pratial per week Credits: 4 Course desription: This ourse desribes the basi theories and priniples of open hannel flow. Topis to be overed are: uniform flow, energ, ontinuit and momentum equations, graduall and rapidl varied flows, hannel ontrols and weirs, design of erodible and non-erodible open hannels, lining of irrigation anals and eonomis of lining,. This ourse ontains some experimental letures (using laborator flume, home works and short reports. Objetive: This ourse provides an introdution to open hannel hdraulis and enable ou to understand and appl the fundamental priniples governing open hannel hdraulis to the design of engineering sstems. This ourse represents a stepping stone in our professional development; it is intended to aid ou in developing the skills in this speialt. t the onlusion of this subjet, students will understand the nature of flows and waves in open hannels and be apable of solving a wide range of ommonl enountered problems. Speifi learning outome: The learner will be able to understand the nature of flow and waves in open hannels and appl the fundamental priniples governing open hannel hdraulis to the design of engineering sstems and be apable of solving a wide range of ommonl enountered problems. Topis Open hannel flow and its lassifiations: Tpes of Channels, Tpes of Flow, Channel Geometr Development of Uniform Flow and its Formulas: Chez's Formula for Uniform Flow, Manning's Formula, Flow Charateristis in Closed Conduit with Open Channel Flow. (Lab. Condition for Most Effiient Cross-Setion, Veloit Distribution Over Cross- Setion of an Open Channel, Measurement of Flow of Irregular Channels Non-Uniform Flow in Open Channels:, Hdrauli Gradient and Total Energ Lines, Energ of Flowing Liquid in Open Channel, Speifi Energ of a Channel's Cross-Setion First Monthl Exam. Speifi Energ Curve, Critial Depth, Tpes of Flow, Disharge-Curve (- Curve, Energ Disharge Curve, Determination of Critial Depth for Retangular Channel. (Lab. Hours

2 Froude's Number, Speifi Energ and Critial Depth for Non-retangular Channel, Classifiation of Slopes Hdrauli Jump: Loation and Tpes of Hdrauli Jump, Height of Hdrauli Jump in Horizontal Channel of Retangular Cross-Setion, (Lab. Length of Hdrauli Jump, Hdrauli Jump in Non-Retangular Channel Seond Monthl Exam. Classifiation of Surfae Profiles in Graduall Varied Flow, Length of Graduall Varied Flow, Diret Step Method (Lab. 4 Channel Transition, Venturi Flume in Channel, Standing Wave Flume, Surges in Open Channels Channel Controls, Sharp Crested Weirs, Broad Crested Weirs, The Over Flow Spillwa, Side Disharge Weir (Lab. 5 Third Monthl Exam. Design of Open Channels, Design of Non-Erodible Channels, Design of Erodible Channels, Stable Hdrauli Setions, The Regime Theor Lining of Irrigation Canals and Eonomis of Lining, dvantage of Lining, Justifiation for Lining Existing Canals Justifiation for Lining Canals on New Projets, Channel Cross-Setion, Permissible Veloities in Lined Channels. Forth Monthl Exam. Hours Hours Hours Text Book: Chow, V.T., 959. Open Channel Hdraulis, MGraw-Hill Referenes: - Henderson, F.M., 966. Open Channel Flow, Prentie-Hall. - Chaudhr, M.H. (008. Open Channel Flow, (nd Edition, Springer. ISBN: R. E. Featherstone and C. Nalluri, 995, Civil Engineering Hdraulis,, rd Edition. - Rihard, H. Frenh, 987. Open Channel Hdraulis. - Terr W. Sturm, 00. Open Channel Hdraulis Grading: - Monthl Exams. 0% - Home works and uizes 5% - Lab. Short Reports (5 5% - Final Exam 50% Laborator: Internal Continuous ssessment (Maximum Marks -5 60% Laborator pratial and short reports

3 0% Tests 0% Regularit in the lab. End Semester Examination (Maximum Marks 0 70% Proedure, Conduting Experiment, results, tabulation and interferene. 0% viva voe 0% Fair reord TU Examination Pattern Part : Short answer questions (5x mark=5marks Part B: naltial / problem solving questions (x5marks=5marks Part C: Desriptive/naltial/Problem solving questions (x0marks=0marks Introdution passage through whih water flows with its free surfae in ontat with the atmosphere is known as Open Channel. The water therefore runs under the atmospheri pressure throughout the open hannel open at the top. Classifiation of Channels: Open hannel ma be lassified as desribed below: a- Channel of regular setion or irregular setion. The retangular, trapezoidal, irular or semiirular setion are examples of hannels of regular setion. The example of hannels of irregular setion are stream or rivers.

4 b- Natural or artifiial hannel Open hannel ma be either natural or artifiial. Streams or rivers are example of natural hannels. rtifiial hannel are man made. - Prismati or non- prismati hannels In prismati hannels, the ross-setion and slope remain uniform throughout its length. rtifiial hannels are prismati hannels. The bed slope and ross setion of non-prismati hannels do not remain uniform throughout the length. Natural hannels are non-prismati hannels. Classifiation of Flow: The flow through the hannel ma be lassified in different tpes as in the ase of the pipe flow: a- Uniform Flow The flow is to be uniform when the veloit of the flow dose note hange both in magnitude and diretion from one setion to another in part of hannel of uniform rosssetion. The Depth of flow must also remain onstant throughout its length for uniform flow. b- Non-Uniform Flow flow is said to be non-uniform when the veloit and depth of flow varies from one setion to another. - Stead flow

5 flow with onstant rate of disharge is known as stead flow. lso, stead flow defined as the flow where the harateristis at a point are not hange with time. d- Unstead Flow flow in whih the rate of disharge dose not remain onstant. e- Graduall Varied Flow When the hange in depth of flow is gradual the flow is said graduall varied flow. Chez Formula for Uniform Flow ❶ L d ❷ F a τ Wsinθ F ❶ Wosθ b W θ ❷

6 ssuming a setion of length L between setion (- and setion (- moving along the hannel as shown in the figure. The water bod (abd is subjeted to the following fores: - Hdrostati fore (F upstream end of the bod. - Hdrostati fore (F downstream end of the bod. - Weight of water bod (W - Fritional resistane fore (τ*pl Sine the water through the hannel flows with uniform veloit, therefore the net aelerating or retarding fore is equal to zero. Hene:- F F W sin PL 0. ( F F (Beause the depth of the flow is onstant W L L g h L v C f ; sin S L Substituting values of W and in the equation ( L g sin C f v PL 0 v g sin C f g C f sin P

7 P g C f R h C v C R S Chez Equation v C RhS Where: =Disharge =Cross setion area C= Chez Coeffiient R h = Hdrauli radius S ο = Longitudinal Slope Ex. trapezoidal hannel has base width of m and side slope of horizontal to vertial. The depth of flow in the hannel is.m. Find Chez onstant if the disharge through this hannel is 700 liter/se and the longitudinal slope of this hannel is to 50. Solution: B Z (. 0.5(..544m

8 P B Z P ( m R m h P m 7. se C R hs 7. C( ( C Ex. The disharge through a semi-irular open hannel is 0m/se. The bed slope is ( to 650 and the hannel is running full. Find the diameter of this hannel if the Chez oeffiient (C is 70. Sol. D C R hs R ; P R R h 0.5R R R

9 R 0 70( R ( ( 650 R (0.07 R. 95m D.95. 9m The Manning s Formula: One of the best as well as one of the most widel used formula for uniform flow in open hannels is that published b the Irish engineer (Robert Manning. Manning found from man tests, that the value of (C in the Chez formula varied approximatel as (R /6, so he proposed the following relation:

10 Ex. s shown in the figure, water flows at a rate of 4 fs in a ver long triangular flume that has side slope :. The flume is laid on a slope and Manning s n is 0.0. Is the flow is subritial or superritial? Sol. T P P R h R h P R h.49 n R h S ( ( ft (.494. ft g T (4. T 96. (. 648 ft The flow is superritial

11 OR:.494 av ft T Fr V g av. ; V 4 ft V 6.7 (.494 se 6.7 Fr.7 The flow is superritial Ex. hannel of trapezoidal setion, m wide at the base with side sloping 45 ο to horizontal arries water at a rate of 6 m /se find: - The depth for ritial flow (. - What is the tpe of flow if the depth of water is m? - Compute Froud Number for normal flow equal to.m. Y 45 ο B=m

12 Sol. tan 45 Z Z g T ; B Z T B Z ( ( 7. ( ( 0. 88m (b trial and error m ; 0. 88m The flow is subritial. m b Z. (..84m T B Z ((. 4. 4m.84 av m T 4.4

13 V 6.56 m.84 se Fr.56 Fr The flow is subritial Ex. trapezoidal hannel arr water at a rate equal to 0m /se, Manning s n is 0.0 and bed slope is The side slope of this hannel Z is :. Compute the bed width (B of this hannel if the allowable veloit of flow is.5m/se. Sol. V 0.5 m B Z B B P B Z P B 5 P R P R.47

14 R n h S ((.47 (0.005 B ( m m Classifiation of Slopes: s alread desribed, the tpe of flow depends upon the depth of flow. There are three tpes of following depth: a- Normal Depth ( n When a hannel of given slope arries uniform flow, then the depth of flow in the hannel is alled (Normal Depth. It is alled normal beause the area of flow must be taken normal to the diretion of flow whih in ase of uniform is parallel to the bed. b- Critial Depth ( lread the definition of the ritial depth have been given the flow is ritial when it is equal to normal depth. - tual Depth ( If the flow in a hannel is of graduall varied tpe, then the depth of flow atuall ourring at a setion is alled (tual Depth.

15 Now, based upon the depth and tpe of flow, the bed slope ma be lassified in to following five tpes: a- Critial Slope The slope of hannel bed is said to be ritial, when the normal depth ( n is equal to the ritial depth (. The ritial slope an be alulated b Manning s formula if the depth ( is known. b- Mild Slope The mild slope of a hannel ma be defined as a slope less than the ritial slope. In this ase the normal depth of flow will be greater than the ritial depth ( n >. - Steep Slope When the slope of a hannel is more than ritial slope, it is said to be steep slope. Hene, the normal depth for uniform flow will be less than ritial depth ( n < and the flow being super ritial flow. d- Horizontal Slope hannel with zero slope is said to be of horizontal slope. e- dverse Slope This is negative slope, where the bed is rises in the diretion of flow.