# Mechanical Engineering - Hydraulic Machines - Discussion

Discussion Forum : Hydraulic Machines - Section 4 (Q.No. 10)
10.
A jet of water is striking at the centre of a curved vane moving with a uniform velocity in the direction of jet. For the maximum efficiency, the vane velocity is __________ of the jet velocity
one-half
one-third
two-third
three-fourth
Explanation:
No answer description is available. Let's discuss.
Discussion:
18 comments Page 1 of 2.

Rajiv said:   12 months ago
@Akhila.

I think the given question is single vane concept. So, pelton wheel concept is not applicable.

Akhila said:   2 years ago
I agree with option A, as pelton wheel has curved moving vanes having max efficiency at 1/2.

Vinay BEL said:   3 years ago
One-half is right.

Sdd said:   4 years ago
Is Pelton turbine blade is curved or flat?

Kartik Oraon said:   4 years ago
@Ali.

What is the formula of efficiency in this case?

Kartik Oraon said:   4 years ago
What is the formula of efficiency, in this case? Is it 2u (1+cos(θ) )/(v-u)?

Ali said:   4 years ago
For plane plate its 1/2 and for curved plate its 1/3.
(1)

Teja said:   5 years ago
Either flat plate or curved vane, the answer is same for the both and it is option A.
(1)

Naga said:   5 years ago
The hydraulic efficiency of an impulse turbine is maximum when the velocity of the wheel is one-half the velocity of a jet of water at the inlet.

Deepak rathva said:   6 years ago
1/3 is correct.
dn/du = 0 for max. n (efficiency).
Solving this we get u = V/3.