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The isentropic heat drop in the nozzle of an impulse steam turbine with a nozzle efficiency 0.9, blade velocity ratio 0.5 and mean blade velocity 150 m/s in kJ/kg is
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- 50
- 40
- 60
- 75
- 50
Correct Option: A
| Blade velocity ratio = | = 0.5 | |
| v1 |
or u = 0.5 v1
where u = mean blade velocity, and
v1 = Absolute velocity of steam at inlet
| = | = 300 m /s | |
| 0.5 |
| K.E. at inlet = | × m × v12 = | (300)2 J | ||
| 2 | 2 |
Nozzle efficiency = 0.9
| ∴ Isentropic heat drop in nozzle = | = 50 kJ/kg | |
| 2 × 0.9 |
