This set of Hydraulic Machines Multiple Choice Questions & Answers (MCQs) focuses on “Work Done by Pelton Turbine”.
1. The work done per unit weight of water jet striking runner blades of Pelton turbine is given by expression ______________
a) [Vw1+Vw2] u/g
b) Vw1*u/g
c) [Vw1+Vw2]/g
d) [Vw1+Vw2]u
View Answer
Explanation: Generally work done is force times velocity and expression for it is PQ [Vw1+Vw2] u/g and work done per unit weight gives [Vw1+Vw2]u/g.
2. In Pelton turbine the energy available at inlet of runner that is at outlet of nozzle is known as
a) Shaft power
b) Runner power
c) Output power
d) Water power
View Answer
Explanation: In Pelton turbine the energy available at inlet of runner that is at outlet of nozzle is known as runner power, the energy available in penstock is water energy.
3. In Pelton turbines the expression for power delivered at inlet to runner is given by __________
a) W*[Vw1+Vw2]u/g
b) W*[Vw1-Vw2]u/g
c) W*[Vw1+Vw2]u/g, W*[Vw1-Vw2]u/g
d) [Vw1+Vw2]u/g
View Answer
Explanation: Generally work done is force times velocity and expression for it is PQ [Vw1+Vw2] u/g and work done per unit weight gives [Vw1+Vw2]u/g.
4. In Pelton turbine runner power is more when compared with power available at exit of nozzle.
a) True
b) False
View Answer
Explanation: Runner power is less when compared with power available at exit of nozzle due to frictional losses.
5. Kinetic energy of jet at inlet of turbine is given as __________________
a) 0.5(paV1)*V1
b) 0.5(paV1)*V1*V1
c) 0.5(aV1)*V1*V1
d) 0.5(pV1)*V1*V1
View Answer
Explanation: Expression for kinetic energy is product of half times mass and square of velocity, mass can be written as density time volume.
Where, p = density of liquid, a = area of jet, V1 = inlet jet velocity
6. The force exerted by a jet of water in the direction of jet of jet on a stationary curved plates Fx is ____________
a) pav*v
b) pav
c) pav*v(1+cos k)
d) pav*v(1+sin k)
View Answer
Explanation: Generally force is rate of change of momentum, in curved blade of angle k change of momentum will be pav*v (1+cos k).
Where, p=density, v=velocity of jet, k=blade angle.
7. The force exerted by a jet of water in the direction of jet of jet on moving curved plates is ___________
a) pa(v-u)*(v-u)
b) pa(v-u)
c) pav*(v-u)(1+cos k)
d) pa(v-u)*(v-u)(1+sin k)
View Answer
Explanation: Generally force is rate of change of momentum, in curved blade of angle k change of momentum will bepav*(v-u)(1+cos k) here relative velocity is considered than absolute.
Where, p=density, v=velocity of jet, k=blade angle, u=blade velocity.
8. Calculate work done by jet per second on the runner where, discharge=0.7cubic meters/s, inlet and outlet whirl velocities be 23.77 and 2.94?
a) 200Kw
b) 150Kw
c) 187Kw
d) 250Kw
View Answer
Explanation: As we know the expression for work done per second is W*[Vw1+Vw2] u/g on substituting the above given values we get it as 187Kw.
9. The power supplied at inlet of turbine in S.I units is known as_____________
a) Shaft power
b) Runner power
c) Water power
d) Total power
View Answer
Explanation: The power supplied at inlet of turbine in S.I units is known as water energy, which contain both kinetic energy and pressure energy.
10.The expression for water power in Pelton wheel is ________________
a) (P*g*Q*H) Kw
b) (g*Q*H*a) Kw
c) (g*Q) Kw
d) (g*H) Kw
View Answer
Explanation: Expression for water power of Pelton turbine is potential energy of water which is converted into kinetic energy
can be written as (P*g*Q*H) Kw.
Sanfoundry Global Education & Learning Series – Hydraulic Machines.
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