ENV3104 Hydraulics II 2018 Assignment 2 Assignment 2 Open Channel and Pipeline Flow: Examiner: Jahangir Alam Due Date: 24 May 2018 Weighting: 15% Objectives 1. Evaluate and apply the equations available for the description of open channel flow 2. Solve simple pipe networks using an appropriate method 3. Apply rigid and elastic water hammer theory to the analysis of pipeline systems 4. Design a range of hydraulic structures including: fixed and movable crest weirs; gated control structures; pipe conveyance structures; spillways and energy dissipation structure; critical flow measuring flumes; gulley control structures; weir and culvert type structures using the minimum specific energy concept. Rationale This assignment is based on the material covered in this course. As such you will be directed to attempt tutorial questions from modules 10, 12 and 16 before starting this assignment Important Information Before starting please review the USQ’s Academic Integrity Policy and Procedure: “All assessable work in a course is to be the individual student’s own work, unless advised otherwise in the Course Specification. It is unacceptable for students to share solutions to assessable work on this Study Desk site, or in any other manner. Violations of this principle are regarded as Academic Misconduct and will be dealt with under the USQ Academic Regulations." For guidance on what constitutes Academic Misconduct and its various categories, at USQ refer to the USQ Student Academic Misconduct Policy available at: http://policy.usq.edu.au/documents/13752PL By submitting this assignment you hereby certify that: The submission is entirely my own work except where due acknowledgement is made in the text and that no part has been copied from any other person’s work. 1 ENV3104 Hydraulics II 2018 Assignment 2 Special Instructions a. Computer programs or spreadsheets must be the work of the individual student. b. Assignments can be validated by using a similar problem where the solution is known c. A proportion of the marks is allocated to the communication aspects of the assignment. Marks will be deducted for untidy and poorly presented work, poor English expression, and failure to cite sources of information. d. This assignment is based on the material contained in Modules 10, 12 & 16. It is essential that students attempt the tutorial problems for these modules before attempting the assignment. e. Plagiarism is taken seriously in this course, as such your assignment report will be checked using Turnitin and your spreadsheets (if you have chosen to use Excel or equivalent) will be checked for plagiarism using Excel-Smash. Any kind of academic misconduct will be dealt with according to the USQ Policy as outlined in the link provided in the previous page. Instructions for Submission Submission for this assignment is in two parts: - Report introducing the problem, description of the methods and equations used, results and brief discussion. - Electronic copy of all computer code or spreadsheets used so the examiner can validate the models (ALL within a single Zip File). The report should be compiled in such a manner that assessment can be completed without access to the electronic copies of the code/spreadsheet files The assignment is to be submitted electronically via study desk. The link is available on the course studydesk. Please note that hand written equations within the body of the report are permitted. Late Submissions If students submit assignments after the due date without (prior) approval of the examiner then a penalty of 10% of the maximum mark applicable for the Assignment for each University Business Day or part Business Day that the Assignment is late up to 10 working days at which time a mark of zero may be recorded. No assignments will be accepted after model answers have been posted Assessment Task This assignment is comprised of three (3) questions with the marks allocated as follows Question 1 – Pipe Network 60 marks Question 2 – Surge Tank 50 marks Question 3 –Control Structure 40 marks 2 ENV3104 Hydraulics II 2018 Assignment 2 Question 1 – Pipe Network (60 Marks) A pipe network system as shown in Figure 1 supplies water from two reservoirs (G & H) to a number of delivery points. The Table shows the details of each pipe. Figure 1 - Pipe network for Q1 The pressure head at points H & G is given in terms of metres head of water (Figure1). You may neglect all minor losses that may occur in the system. Pipe AB BC CD DE EA AF FD GC HA Length (m) 160 350 280 560 190 230 210 125 125 Diameter (mm) 200 200 180 180 185 185 160 250 250 Roughness (mm) 0.09 0.10 0.07 0.12 0.13 0.14 0.16 0.08 0.08 a) Use the linearisation method to solve for the unknown discharges in each pipe of the network. b) Assuming the network is situated on a level grade estimate the pressure head in metres at each pipe junction (A, B, C, D, E, F) HINT: The partial loop from H, A, B, C, G can be analysed as a normal loop once you account for the difference in energy (water level) between the reservoirs. Nodes H and G do NOT have node equations you only need to remove node equations if you have too many equations You should end up with 3 loops 3 ENV3104 Hydraulics II 2018 Assignment 2 Question 2 – Surge Tank (50 Marks) A hydroelectricity plant is supplied from a reservoir via a pipeline 1.8 km long and 3 m in diameter. This pipeline is made of cast iron (k=0.25 mm) and terminates at its downstream end in a control valve. The water level at the reservoir is maintained at a constant 25 m above the inlet end of the pipeline. You have been given the task of determining the size of the surge tank which is to be installed at the downstream end of this pipeline and immediately upstream of the valve. This tank must be designed in order to deal with the surge that would occur when the valve downstream of the tank is closed completely and instantaneously. Model the flows within the pipe and surge tank using the numerical solution technique (equations 12.21 & 12.22) described by Marriott (Nalluri and Featherstone) in Section 12.4. You should use a time step of 5 seconds or smaller and account for the change in f with velocity. Surge Tank Design Criteria: Unrestricted inlet (FS = 0) Under normal operating conditions the hydro plant will run with a steady discharge of 10 1 m3/s, where N 1 is the last digit of your student number. Maximum allowable water height in the tank is 5 m above level in reservoir. Task: a) Determine the minimum surge tank size (nearest ½ m) to satisfy the max. allowable height For the case of complete closure (Q changes from 10 1 m3/s to 0 m3/s) b) Plot the water level in the surge tank (relative to reservoir) over time for at least 2 upsurges c) Plot the velocity in the pipeline over the same period (different set of axes). HINT- The initial water level in the tank is below the level in reservoir by distance of hf at full flowing condition 4 ENV3104 Hydraulics II 2018 Assignment 2 Question 3 – Control Structure (40 Marks) A reservoir supplies water to an irrigation scheme via a diversion channel. The channel is 2 m wide and is constructed of concrete with Manning n 0.016. The bed slope of the channel is 0.0017. The discharge into the channel is controlled by a vertical sluice gate (Cc = 0.61). The water depth in the upstream of the gate is maintained at a constant depth of 2.9 m, and the maximum allowable discharge to the diversion channel is 12 m3/s. The depth on the downstream side of the gate is at normal depth. You have been asked to develop the rating curve for the sluice gate (YG vs Q). Table below is incomplete tasks for this rating curve. Q (m3/s) 1 2 3 4 5 6 7 8 9 10 11 12 Yg (free flowing) Yg (for submerged) Yn or Y3 (m) 0.110 0.222 0.337 0.455 0.575 0.698 0.824 ?? ?? ?? ?? ?? (m) ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? ?? 3.121 (m) 0.431 0.701 0.943 1.171 1.392 1.607 1.819 ?? ?? ?? ?? ?? Your Tasks: (a) Calculate the missing gate openings for free flowing condition and normal depth in the table. (b) Determine at what discharge the gate changes from freely flowing to submerged conditions (to the nearest m3/s) (c) Calculate the new gate opening (YG) for those discharges for where the gate is submerged by the depth downstream of the gate. (d) Plot the rating curves (show both the free flowing and altered part where the gate is submerged) HINT: See section 13.8 and Example 13.6 in Chadwick et al. (provided on Studydesk) 5 ENV3104 Hydraulics II 2018 Assignment 2 Marking Scheme Question 1 – Pipe Network Items Requirements Formulation of Equations Method Diagram with assumed flow directions Continuity (node) equations energy loop equations Correctly accounted for pump or valve, if any Model uses the linearization method Model is correct Calculates friction properly Accounts for pump or valve, if any Correct solution for the flows Correct solution for the heads Solution process Results (including impact of Valve, if any) Following report format Marks 15 15 Solution for Q Calculation of Heads Discussion & Presentation Penalty (+/- 0.5 L/s) 10 10 10 No electronic copy of model (-10 ) 60 Total 6 ENV3104 Hydraulics II 2018 Assignment 2 Question 2 – Surge Tank Requirements Equations introduced Sample hand calculations and/or explanation of method a,b,c change sign with neg. velocity Model is correct Calculated the new f from Vi in each time step (Bar or Colebrook-White) 5 The surge tank design criteria met 10 Explanation on how the size was determined Results are correct (14) Plot Z with time (at least 2 upsurges) (3) Plot V with time (at least 2 upsurges) (3) Δt is too large (-5) Missing electronic copy of model (-10) Method Variable friction Tank Size for max Height Solution Penalty Marks 15 20 50 Total Question 3 – Control Gate Items Requirements Marks Equations and Diagram Labelled diagram Equations are introduced 5 Free flowing gate openings Varied Cd for each opening yg values are correct 5 7 ENV3104 Hydraulics II 2018 Assignment 2 Determining when gate is submerged Apply the hydraulic jump equation Sample hand calc or explanation 10 New yg for submerged Method is correct sample hand calc or explanation 10 Rating Curve Plotted the curves with given yg 10 40 Total References Chadwick, A., Morfett, J. And Borthwick, M. 2013, Hydraulics in Civil and Environmental Engineering. 5th Edition E & F N Spon. Marriott, M. 2016, Nalluri and Featherstone’s Civil Engineering Hydraulics. 6th Edition, WileyBlackwell. Kraatz. D.B. & Mahajan I.K. 1975, Small Hydraulic Structures, FAO Irrigation and Drainage Paper 26/2. FAO, Rome 8