Question

For a non-dimensional specific speed value of 1, for maximum efficiency, which of the following turbines is preferred?
1. Pelton wheel
2. Francis turbine
3. Kaplan turbine
4. Tyson wheel

Answer 1

Correct Answer - Option 2 : Francis turbine

Non-dimensional specific speed is given by

\({N_S} = \frac{{N\sqrt P }}{{{{\left( {gH} \right)}^{\frac{5}{4}}} \cdot \sqrt \rho }}\)

The Range for non-dimensional specific speed is given in the table below

Non-Dimensional specific speed	Type of turbine
Less than 0.18	Single jet Pelton
0.18 – 0.30	Multi Jet Pelton
0.30 – 1.50	Francis
1.50 – 5.12	Kaplan