Topic: Fluid Machinery
Given that $\alpha_{1}=$ nozzle angle, $n=$ number of rows of moving blades, in a velocity compounded impulse turbine, the optimum blade speed ratio is
- A. $2~cos~\alpha_{1}.n$
- B. $\frac{n~cos~\alpha_{1}}{2}$
- C. $\frac{cos~\alpha_{1}}{2(n+1)}$
- D. $\frac{cos~\alpha_{1}}{2n}$
Answer: D. $\frac{cos~\alpha_{1}}{2n}$
Explanation: For a velocity compounded impulse turbine with $n$ rows of moving blades and nozzle angle $\alpha_1$, the optimum blade speed ratio is given by $\frac{cos~\alpha_{1}}{2n}$.