2021 May CIVE210 Hydraulics PDF

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Email: [email protected] CIVE210 HydraulicsSecond Semester Open Book Examinations 2021Bachelor of Engineering Yr 2 (CIVE210)Master of Engineering Yr 2 (CIVE210)HydraulicsStudent DeclarationBy undertaking this assessment you confirm that you have been acting honestly, ethically and professionally. And...

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Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

Second Semester Open Book Examinations 2021 Bachelor of Engineering Yr 2 (CIVE210) Master of Engineering Yr 2 (CIVE210)

Hydraulics

Student Declaration By undertaking this assessment you confirm that you have been acting honestly, ethically and professionally. And you have not committed plagiarism nor colluded with any other student during this assessment. TIME ALLOWED: 240 minutes including the time for upload

INSTRUCTIONS TO CANDIDATES:

This is an open-book exam assessment. You can access resources to answer questions. You will not be expected to access information/knowledge beyond that provided in your lectures and module Canvas sites to answer the questions.

Timing: The timing stated is a total time for the assessment including download and upload times. You should normally allow about 30 minutes to scan and upload any written answers.

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Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

Answers can be hand-written and/or typed, with a strong preference for hand-written to show your personal work. All documents should be scanned into one pdf document for upload. Taking photographs from the screen and including in the pdf also works well (you can do this to include the submission upload cover sheet).

Use a black pen and white paper with faint lines to guide your handwriting when writing. Ensure your handwriting is clear and readable. These requirements will be relaxed, with prior agreement, for students with disability support plans.

You must include a completed “Submission Front Sheet” (that is available on the next page and as a separate file) as the first page for ALL uploads to Canvas. File names must be: Module Code Student, ID number, and family name (e.g. CIVE210_1234567Smith). One single file should be submitted.

Upload your pdf answer document to Canvas using the Turnitin Assignment or similar link provided in your module. This must be comleted within the allotted time for this exam. Check that you get a VITAL/Canvas receipt when you submit successfully. If you do not obtain a receipt, then inform the School’s Student Support Office at [email protected]. If you experience technical difficulties which disrupt your exam or your upload of answers, please inform the Student Support Office immediately, and they will provide you with an “Exam Disruption” form to complete.

If you have any queries during the exam period, you may email the Module Leader (using the email at the top of this paper), who will reply to you individually. If there is a query relevant to the whole class, then the Module Leader will send an email announcement through VITAL/Canvas to everyone. So, please check your emails during the exam period.

The Module Leader will be present online for the entire 3 or 4 hours of “short” open-book exams.

Answer ALL questions.

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Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

Q1 A straight and horizontal pipeline with diameter of 0.8m conveys crude oil (density is 950 𝑘𝑔/𝑚3 , kinematic viscosity is 1.2 × 10−5 𝑚2 /𝑠 ). The pipe wall is assumed to be smooth and the corresponding friction factor can be found from the Moody Diagram (in the Supplementary Information sheet). To maintain the oil flow rate, pressure boosters are distributed every 20 𝑘𝑚 along the pipeline.

(a) If the oil flow rate is 0.45 𝑚3 /𝑠, determine the flow state and the amount of pressure that needs to be raised at each pressure booster. [12/25] (b) If the pipe is not smooth but has a roughness of 16mm, how much should the pressure be boosted to maintain the same flow rate as in (a)? [6/25] (c) If the pipeline is gradually expended as shown in Figure 1, sketch the Hydraulic Gradient Line (𝑧 +

𝑝

) and the Total Energy Line (𝑧 + 𝜌𝑔

𝑝

+ 𝜌𝑔

𝑢2 ) 2𝑔

before and after the expansion (before

section ① and after section ②) and briefly discuss the trend of two lines. 𝑧 is the horizontal central line of the pipeline, 𝑝 is the pressure, 𝑢 is the velocity of the flow in the pipeline, 𝜌 is the density of the fluid and 𝑔 is gravitational acceleration. [7/25]

①

② Figure 1: Pipeline expansion

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Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

Q2 (a) Use the Hardy-Cross method to determine the flow rates and their directions in all the pipes of the network as shown in Figure 2 with inflow/outflow at each junction given. Head loss due to friction in all the pipes may be taken as (𝑓𝐿𝑄 2 )/(π2 𝑔𝐷 5 ) where 𝑄 is the flow rate. The pipe diameter 𝐷, length 𝐿 and friction factor 𝑓 are given in the table. All other losses are negligible. [15/25]

Pipe AB BC CD DA

Diameter D (m) 0.35 0.5 0.35 0.4

Length L (m) 300 300 300 300

Figure 2(a): Pipe network

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Friction factor f 0.02 0.05 0.03 0.02

Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

(b) Water in the lower reservoir (250m A.O.D) is to be pumped to a higher reservoir (300m A.O.D) via a pipe with diameter of 0.5m and length of 800m as shown in Figure 2(b). The flow is driven by a centrifugal pump and its characteristic curve is 𝐻𝑝 = 200 – 650𝑄 2 where 𝐻𝑝 is the pump head and 𝑄 is the flow rate in the pipe. i. Calculate the flow rate in the pipe and the head of the pump assuming the friction factor in the pipe is 0.03 and all other losses are negligible. [7/25] ii. Describe, within 50 words, how to determine the pump is operating efficiently using pump efficiency curve. [3/25] Higher reservoir 300m

Lower reservoir 250m

Figure 2(b)

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Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

Q3 A spillway is to be designed for a dam as shown in Figure 3. The flow rate Q over the spillway is determined by the width W, water head H over the spillway, density of water 𝜌, dynamic viscosity 𝜇 and gravitational acceleration g.

Figure 3 (a) Find out a set of independent non-dimensional 𝜋 groups using Buckingham method with repeating variables of Q, 𝜌 and H. [15/25]

(b) The design discharge over the spillway is 100𝑚3 /𝑠 with 3m in water head and 20m in width for the prototype. A hydraulic model is to be used to confirm the estimates of the spillway performance. If the model has 30cm water head, determine the width of the spillway in the model and the flow rate tested in the model if the viscous effect is neglected. [10/25]

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Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

Q4 (a) A trapezoidal canal shows a rough reach followed by a relatively smooth reach of the same slope 𝑆0 = 0.0045, with the cross sectional and longitudinal views shown in Figure 4. The normal depth of flow on the rough reach is 0.8m for the flow rate of 8.7𝑚3 /𝑠.

Cross sectional view

longitudinal view Figure 4

(i) If the Manning’s coefficients is 0.01 𝑚−1/3 𝑠 for the smooth reach, calculate the normal depth for the smooth reach. [8/25] (ii) Calculate critical depth for both reaches and determine their slope types. [8/25] (iii) Sketch the water surface profiles; [4/25]

(b) Sketch the surface profile after the sluice gate in the channel below and identify the profile type [5/25]

Flow

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Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

Supplementary Information Moody diagram

Reynolds Number: 𝑹𝒆 =

𝑽𝑫𝝆 𝑽𝑫 = 𝝂 𝝁

where Re is the Reynolds Number, V is the velocity, D is the pipe diameter, ρ is the fluid density, μ is the dynamic viscosity and ν is the kinematic viscosity.

Manning’s equation: 𝑽=

𝟏 𝟐/𝟑 𝟏/𝟐 𝑹 𝑺 𝒏 𝒅 𝒐

where V is the mean velocity, n is Manning’s roughness factor, Rd is the hydraulic radius and S0 is the bed slope.

Critical flow equation: 𝑸𝟐 𝑻 =𝟏 𝑨𝟑 𝒈 where 𝑸 is the flow rate, 𝑻 is the width at the flow surface, 𝑨 is the cross sectional area and 𝒈 = 𝟗. 𝟖𝒎/𝒔𝟐 is acceleration of gravity.

Pipe friction loss: 𝒉𝒇 =

𝒇𝑳𝑽𝟐 𝟐𝒈𝑫

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Module leader: Dr Yan Zhou Email: [email protected]

CIVE210 Hydraulics

where 𝑅𝑒 is Reynolds number, 𝑔 = 9.8𝑚/𝑠 2 is acceleration of gravity, 𝐿 and 𝐷 are length and diameter of the pipe respectively.

Channel parameters Trapezoidal channel

Surface width B

Area A

Perimeter P

𝒃 + 𝟐𝒛𝒉

(𝒃 + 𝒛𝒉)𝒉

𝒃 + 𝟐𝒉√𝟏 + 𝒛𝟐

Gradually varied flow profiles

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Radius 𝑹𝒅

(𝒃 + 𝒛𝒉)𝒉 𝒃 + 𝟐𝒉√𝟏 + 𝒛𝟐...