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Difference between GD¦ vaue and Moment of inertia of pump
- Thread starter nirlt
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GD^2? What are you trying to do and what's the rest of the formula?
Wet Moment of Inertia of pump + motor is used for determination of angular acceleration during starts, stops and speed changes.
Wet Moment of Inertia of pump + motor is used for determination of angular acceleration during starts, stops and speed changes.
PersonalProfile
Mechanical
Are you referring to GD^2 and Mr^2 where the difference is 2^2 = 4?
That is you are talking about the same measurement, less two different systems of measurement?
Regards,
Lyle
That is you are talking about the same measurement, less two different systems of measurement?
Regards,
Lyle
Hi,
GD^2, or PD^2 as it can be also found, is the "old" way of expressing the polar inertia of a shaftline. As Lylebrown says, it is 4 times the value of the inertia. "GD^2" is however mostly used in hydraulic turbomachinery.
As it has been already said, the rotary inertia of the shaftline influences the transient operations (startup, shutdown, load rejection, runaway); the bigger the inertia, the slower the shaftline can vary its speed in response to transient conditions. For example, if you have a mandatory specification on the max overspeed during load rejection, increasing the inertia is one way to keep under the specification. Ah, well, I'm speaking of a turbine, but the same concepts apply to pumps of course.
Regards
GD^2, or PD^2 as it can be also found, is the "old" way of expressing the polar inertia of a shaftline. As Lylebrown says, it is 4 times the value of the inertia. "GD^2" is however mostly used in hydraulic turbomachinery.
As it has been already said, the rotary inertia of the shaftline influences the transient operations (startup, shutdown, load rejection, runaway); the bigger the inertia, the slower the shaftline can vary its speed in response to transient conditions. For example, if you have a mandatory specification on the max overspeed during load rejection, increasing the inertia is one way to keep under the specification. Ah, well, I'm speaking of a turbine, but the same concepts apply to pumps of course.
Regards
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