Themes > Science > Physics > Mechanics > Fluid Mechanics > Past Examination Solutions > June 1998 > Question 7

7.a Define the following terms in connection with the flow of a liquid
    1. Uniform flow
    2. Steady flow
    3. Unsteady flow
    4. Mean velocity
    5. Discharge
    6. Mass flow rate
    7. Continuity

(14 marks)

 

7.b Oil flows in a pipe which contracts from 450mm diameter at point A to 300mm at point B then splits into to branches of diameters 150mm and 225mm discharging at C and D respectively.

If the velocity at A is 1.8m/s and the velocity at D is 3.6m/s, what is the discharge at C and D and the velocity at B and C?

(3 marks)

7.c If point A is 10m higher than point B and the pressure at A is 10kN/m2, what is the pressure at point B?

(3 marks)

 

 

7.a

A minimum of 3 lines per description is required - preferably more with simple examples. Four or five words is NOT sufficient and you will get no marks.

7.b

vA = 1.8 m/s

AA = p 0.452 / 4 = 0.159 m2

vD = 3.6 m/s

AD = p 0.2252 / 4 = 0.0398 m2

QA = vA AA = 0.286 m3/s

AB = p 0.32 / 4 = 0.0707 m2

AC = p 0.152 / 4 = 0.0177 m2

QA = QB = 0.286 = AB vB

vB = 0.286 / 0.0707 = 4.0545 m/s

QD = AD vD = 3.6 ´ 0.398 = 0.1439 m3/s

QC = QA - QD = 0.1427 m3/s

vC = QC / AC = 0.14272 / 0.0177 = 8.063 m/s

 

7.c


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