## Fluid Mechanics and Hydraulic Machinery Miscellaneous

#### Fluid Mechanics and Hydraulic Machinery

1. For a fully developed flow through a pipe, the ratio of the maximum velocity to the average velocity is _________(fill in the blanks)

1. Two

##### Correct Option: A

Two

1. The discharge in m3 / s for laminar flow through a pipe of diameter 0.04 m having a centre line velocity of 1.5 m/s is

1. umax = 2 uavg
umax = 2 uavg
1.5 = 2uavg

 uavg = 1.5 m /s 2

Q = A × V = A × uavg
 Q = π d2 × uavg 4

 = π × (0.04)2 × 1.5 = 3π m3 /s 4 2 10000

##### Correct Option: D

umax = 2 uavg
umax = 2 uavg
1.5 = 2uavg

 uavg = 1.5 m /s 2

Q = A × V = A × uavg
 Q = π d2 × uavg 4

 = π × (0.04)2 × 1.5 = 3π m3 /s 4 2 10000

1. Shown below are three tanks, tank 1 without an orifice tube and tanks 2 and 3 with orifice tubes as shown. Neglecting losses and assuming the diameter of orifice to be much less than that of the tank, write expressions for the exit velocity in each of the three tanks.

1. V1 = √2gH
V2 = √2g(H + L)
V3 = √2g(H + L)

##### Correct Option: D

V1 = √2gH
V2 = √2g(H + L)
V3 = √2g(H + L)

1. Consider steady flow of water in a situation where two pipe lines (pipe 1 and pipe 2) combine into a single pipe line (pipe 3) as shown in figure. The cross-sectional'area of all three pipelines are constant. The following data is given

Assuming the water properties and the velocities to be uniform across the cross-section of the inlets and the outlet, the exit velocity (in m/s) in pipe 3 is

1. Q1 + Q2 = Q3
A1V1 + A2V2 = A3V3
1 + 4 = 2.5 V3
or V3 = 2 m/s

##### Correct Option: C

Q1 + Q2 = Q3
A1V1 + A2V2 = A3V3
1 + 4 = 2.5 V3
or V3 = 2 m/s

1. As the transition from laminar to turbulent flow is induced in a cross flow past a circular cylinder the value of the drag coefficient drops.

1. True

True