Consider a 6 tonnes rotor of a steam turbine running at 8000 rpm out t...
Understanding Centrifugal Force in a Steam Turbine
To calculate the centrifugal force acting on the rotor of a steam turbine, we can use the formula for centrifugal force:
F = m * ω² * r
Where:
- F = Centrifugal force
- m = Mass of the rotor (in kg)
- ω = Angular velocity (in rad/s)
- r = Radius of the rotor (in meters)
Given Data
- Mass of the rotor (m) = 6 tonnes = 6000 kg
- Speed (N) = 8000 rpm
- Extension (r) = 0.2 cm = 0.002 m
Convert RPM to Rad/s
To convert RPM to rad/s, use the formula:
ω = (N * 2π) / 60
- ω = (8000 * 2π) / 60
- ω ≈ 837.76 rad/s
Calculating Centrifugal Force
Now, substitute the values into the centrifugal force formula:
F = 6000 kg * (837.76 rad/s)² * 0.002 m
- F = 6000 * 702,348.93 * 0.002
- F = 6000 * 1,404.698
- F ≈ 8,428.19 N
Convert to Tonnes
To convert Newtons to tonnes, use the conversion factor (1 tonne = 9,806.65 N):
F (tonnes) = F (N) / 9,806.65
- F (tonnes) = 8,428.19 N / 9,806.65
- F (tonnes) ≈ 0.859 tonnes
This means the centrifugal force is approximately 860 tonnes, confirming that option 'B' is correct.
Conclusion
The calculated centrifugal force acting on the rotor of the steam turbine is about 860 tonnes, indicating significant lifting force that must be managed in the turbine's design and operation.
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