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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 2009/
School: Engineering – Civil, Structural and Environmental
Programme Title: Bachelor of Engineering (Honours) in Structural Engineering – Stage 2
Programme Code: CSTRU_8_Y
Module Title: Fluid Mechanics
Module Code: CIVL
External Examiner(s): Mr. John O’Mahony and Dr. Mark Richardson
Internal Examiner(s): Ms. N. Hurley
Instructions: Answer FOUR questions
Duration: 2 Hours
Sitting: Autumn 2010
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you are attempting the correct examination. If in doubt please contact an Invigilator.
Q1. (a) Explain, with the aid of diagrams, capilliarity, vapour pressure and cavitation. (10 marks)
(b) In Hydrostatics, what is Pascals Law? And what is the relationship between depth, gravitational acceleration, density and pressure? (10 marks)
(c) The top of an inverted U-tube manometer is filled with oil of specific gravity 0.98 and the remainder of the tube filled with water of specific gravity 1.01. Find the pressure difference in newtons per square metre between two points at the same level at the base of the legs when the difference of water level is 75mm. (5 marks) pb – pa = ρg (b – a) + gh (ρ – ρman)
Q2. (a) What is meant by uniform, steady flow? (5 marks)
(b) What is the Continuity Equation and give examples of its applications? (8 marks)
(c) A closed tank of fixed volume is used for the continuous mixing of two liquids which enter at A and B and are discharged completely at C. The diameter of the inlet pipe at A is 150mm and the liquid flows in at the rate of 56 10 -3^ m^3 /s and has a specific gravity of 0.93. At B the inlet pipe is of 100mm diameter, the flow rate is 30 x 10^3 m^3 /s and the liquid has a specific gravity of 0.87. If the diameter of the outlet pipe at C is 175mm, what will be the mass flow rate, velocity and specific gravity of the mixture discharged? (12 marks)
Q3 (a) Bernoullis Equation (the Energy Equation) states that, for flow along a steamline, the total energy per unit weight remains constant from point to point, although the division of energy between three forms may vary. Define and describe these three forms of energy? And what are the units of each? (15 marks)
(b) In an experiment on a 90o^ vee notch the flow is collected in a 0.9m diameter vertical cylindrical tank. It is found that the depth of water increases by 0.685m in 16.8 s when the head over the notch is 0.2 m. Determine the coefficient of discharge of the notch. Q = 8 / 15 √(2g) tan θ/2 H5/2^ Cd = Qactual Qtheoretical (10 marks)
