Quiz: Civil Engineering

Exam: NPCIL-SCINTIFIC ASSISTANT(CIVIL)

Topic: Hydraulics & Fluid Mechanics

Each question carries 1 mark

Negative marking: No negative marking

Time: 10 Minutes

Q1. Francis turbine is a:

(a) Axial flow turbine

(b) Radial flow turbine

(c) impulse turbine

(d) Outward flow turbine

Q2. In reaction turbine-

(a) flow can be regulated without loss

(b) water may be allowed to enter apart of whole of wheel circumference

(c) the outlet must be above the tail race

(d) there is only partial conversion of available head to velocity head before entry to runner

Q3. Kaplan turbine-

(a) has poor part-load efficiency

(b) is used where high head is available

(c) has inlet adjusted guided vanes

(d) has adjustable runner blades

Q4. Weber number is the ratio of inertial force to

(a) gravitational force

(b) surface tension

(c) elasticity

(d) viscosity

Q5. A Pelton wheel is:

(a) Radial flow impulse turbine

(b) Inward flow impulse turbine

(c) Axial flow impulse turbine

(d) Outward flow impulse turbine

Q6. Maximum theoretical efficiency of Pelton wheel is obtained when the ratio of bucket speed to jet speed is:

(a) 0.26

(b) 0.98

(c) 0.46

(d) 0.58

Q7. Bulk modulus of a fluid is the ratio of

(a) shear stress to shear strain

(b) increase in volume to the viscosity of fluid

(c) increase in pressure to the volumetric strain

(d) critical velocity to the velocity of fluid

Q8. The velocity distribution for flow between two fixed parallel plate_______________.

(a) Is constant over the cross-section

(b) Is zero at the plates and increases linearly to the mid-plane

(c) Varies parabolically across the section

(d) Is zero in middle and increase linearly towards the plates

Q9. The total line lies over the hydraulic gradient line by an amount equal to:

(a) Velocity head, V²/2g

(b) datum head, Z

(c) Sum of pressure, velocity and datum heads

(d) Pressure head, P/y

Q10. A compound pipe system consists of 1800m of 50cm, 1200m of 40cm and 600m of 30cm cast iron pipes connected in series. If this system is converted into an equivalent length of 40 cm pipe, the length will be

(a) 4300m

(b) 4320 m

(c) 4310 m

(d) 4380m

SOUTION

S1. Ans.(b)

Sol. Francis turbine is inward flow radial reaction turbine.

S2. Ans.(d)

Sol. in a reaction turbine, there is only partial conversion of available heat to velocity head before entry to runner. Thus at entrance to reaction turbine the fluid will have both pressure energy as well as kinetic energy.

S3. Ans.(d)

Sol. Kaplan turbine has adjustable runner blade due to that it has high part load efficiency.

S4. Ans.(b)

Sol. Weber number is the ratio of intertie force to surface tension.

S5. Ans.(b)

Sol. Pelton wheel is the turbine comes in category of inward flow impulse turbine.

S6. Ans.(c)

Sol. maximum actual efficiency.

When

V = 2u

u = 0.5 V

but,

Theoretically maximum efficiency.

▭(u=0.46V)

S7. Ans. (c)

Sol. ▭(Bulk modules = (Increase in pressure )/(volumetric strain ))

S8. Ans.(c)

Sol.

S9. Ans.(a)

Sol.

S10. Ans.(b)

Sol.

L₁ = 1800 m L₂ = 1200 m L₃ = 600 m

D₁ = 50 cm D₂ = 40 cm D₃ = 30 cm

→ In series connection discharge is constant

L/(D)^5 = L_1/(D_1 )^5 + L_2/(D_2 )^5 + L_3/(D_3 )^5

L_2/(40)^5 = 1800/(50)^5 + 1200/(40)^5 + 600/(30)^5

L = 4320 m