1) An oil of viscosity 0.2 pas flows between two stationary parallel plates which are kept at a distance of 10 mm apart. The plates are 1 m wide and the centre line flow velocity is stated to be 2.5 m/s. Determine the average flow velocity, flow rate of oil, pressure gradient and the wall shear stress.
Answer:
(i) 1.67 m/s, (ii) 0.0167 m3 / s, (iii) 4000 N/m2 per meter, (iv) 20 N/m2
2) There is horizontal crack 5 cm wide and 3 mm deep in a wall of thickness 15 cm. Water leaks through the crack. Find the difference of pressure between the two- ends of the crack if the rate of leakage of water through the crack is 0.1875 lit/sec.
Answer:
(p1 – p2) = 250N/m2
3) An oil of specific gravity 0.9 and viscosity 0.06 poise is flowing through a pipe diameter 200 mm at the rate of 60 lit/set. Find the head lost due to fiction for a 500 m length. Find also the power required to maintain the Flow.
Answer:
(i) 9.49 m of water (ii) 5.027 Kw
4) The rate of flow of water through a horizontal pipe is 300 lit/sec. The pipe of diameter 200 mm is suddenly enlarged to 400 mm find (i) loss of head (ii) change in pressure (iii) loss of fluid power
Answer:
(i) 2.617 m of water
(ii) 17.02 kpa
(iii) 7.70 Kw
5) Water is flowing between tow larger parallel plates which are 2.0 mm apart. Determine (i) maximum velocity (ii) the pressure drop (iii) shear stress at walls of the plate if average velocity is 0.4 m/s. Take viscosity of water as 0.01 poise.
Answer:
(i) 0.6m/s
(ii) 1199.7 N.m2 per meter
(iii) 1.199N/m3
6) A pipe of 60 mm diameter and 450 m long slopes upwards at 1in 50. An oil of viscosity 0.9Ns/m2 and specific gravity 0.9 is required to be pumped at the rate of 5 lit/sec. (i) It the laminar flow (ii) What is the pressure difference is required to attain this condition? (iii) What is the power of pump required assuming an overall efficiency of 65% (iv) What is the centre line velocity and velocity at pipe wall?
Answer:
(i) Laminar
(ii) p1 – p2 6.44 mpa
(iii) U = 3.534 m/s
(iv) du/dy = 238.5 per sec
7) A plate 450 mm x 150 mm has been placed longitudinally in a stream of crude oil (S = 0.925 and kinematics viscosity of 0.9 stokes) which flow with velocity of 6 m/s. Calculate (i) Friction drag on the plate (iii) Thickness of the boundary layer at the trailing edge and (iii) Shear stress at the trailing edge.
Answer:
FD = 8.62 N, δ = 13mm, τo = 63.77 N/m2
8) A thin plate is moving in still atmospheric air at a velocity of 4 m/s. The length of the plate is 0.5 m and width 0.4 m. Calculate the (i) thickness of the boundary layer at the end of the plate (ii) drag force on one side of the plate. Take density of air as 1.2Kg/m3 and kinematic viscosity 0.15 stokes.
Answer:
(i) 0.672 cm (ii) 0.00728 N
9) Water is flowing through a horizontal pipe of diameter 200 m at a velocity of 3 m/s. A circular solid plate of diameter 150mm is placed in the pipe due to obstruction in the pipe. Tale co-efficient of contraction in the pipe is 0.65. Find also loss of fluid power.
Answer:
(i) 2.905m of water
(ii) 2.6Kw
10) Find the head lost due to friction in a pipe of diameter 250 mm and length 60m, through which water is flowing at a velocity of 3.0 m/s using (i) Darcy formula (ii) Chezy's formula. Take C = 55 & v after water is 0.01 stoke.
Answer:
(i) 1.182
(ii) 2.856
11) Pipes of 50 cm diameter 1800 m length, 40 cm diameter 1200 m length, 30 cm diameter 600 m lengths are connected in series.
(i) If these pipes are to be replaced by an equivalent pipe of 40 cm diameter,
what would be its length?
(ii) What would be the diameter of equivalent pipe of 3600 m length.
(iii) If the three pipes are connected is parallel, what is the equivalent length of a 50 cm diameter pipe?
Answer:
(i) L = 4318.2m
(ii) D = 38.6cm
(iii) L = 377.37 m
12) Find the rate of flow through a horizontal pipe line 40 m long connected to a water tank at one end and discharges freely into the atmosphere at the other end. For the first 25 m of its length from the tank, the pipe is 150 mm diameter and its diameter is suddenly enlarged to 300 mm. The height of water level in the tank is 8 m above the centre of pipe. Considering all minor losses take co-efficient of friction as 0.01
Answer:
78.63 lit/sec
13) Water is discharged from one tank to another with 40 m difference of water levels through a pipe 1200 m long. The diameter for the first 600m length of pipe is 400 mm and 250 mm for the remaining 600 m length. Find the discharge in lit/sec through pipe. Assume co-efficient of friction as 0.009 for both the pipes. Neglect minor losses.
Answer:
140.78 lit/sec
14) Determine the difference in the elevations between the water surfaces in the two tanks which are connected by a horizontal pipe of diameter 400 mm and length 500 m. The rate of flow of water through the pipe is 200 lit/sec consider all losses and take the value of f = 0.009.
Answer:
11.79 m
15) The rate of flow of water through a horizontal pipe is 0.3m3/s. The diameter of the pipe is suddenly enlarged from 250 mm to 500 mm. The pressure intensity in the smaller pipe is 13.734N/cm2.
Determine (i) loss of head due to sudden enlargement (ii) pressure intensity in the lower pipe (iii) power lost due to enlargement.
Answer:
(i) 1.07m
(ii) 14.43 N/cm2
(iii) 3.15 Kw
16) Three pipes
(a) L1 = 300m, D1 = 30cm, f1 = 0.018
(b) L2 = 150m, D2 = 20cm, f2 = 0.02
(c) L3 = 200m, D3 = 25cm, f3 = 0.019 are
Connected in series between two reservoirs having difference in surface level= 15 m. Considering all types of losses, find discharge to lower reservoir. Draw HG and EG lines
Answer:
105.7 LPS
17) A 300 mm diameter pipe, 3.2 km long, connects two reservoirs with 15 m in diameter, at a pressure of 3kg/cm2. If the discharge end of the pipe has a nozzle, fine its diameter for efficient power transmission. Take f = 0.032
Answer:
d = 2.65 cm
18) Three pipes of length 50 m each pipe of diameter 12, 10 and 8 cm respectively are connected in series. Find length of the pipe of diameter 10 cm equivalent to above pipes laid is series. Take same co-efficient for all pipes
Answer:
267 m
19) Find the maximum power transmitted by a jet of water discharging freely out of a nozzle fitted to a pipe of length 300m and 10 cm diameter. Head available at inlet is 90 m. f = 0.01
Answer:
P = 20.64 Kw
20) For a two water supply, a main pipe line of diameter 0.4 m is required. As pipes more than 0.35 m diameter are not readily available, two parallel pipes of same diameter are used for water supply. If the total discharge in the parallel pipes to same as in the single main pipe. Find the diameter of parallel pipe. Assume co- efficient of discharge to be the same for all the pipes.
Answer:
0.3031m
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