Thread: CIM Quiz 2
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Unread 02-12-2010, 11:51
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Re: CIM Quiz 2

Quote:
Originally Posted by JesseK View Post
Is the "Power" required to drive the impeller electrical watts or mechanical watts?
The impeller is driven mechanically by the two motors (through their respective gearboxes). The formula watts = (rpm^2)/81500 gives the mechanical power input to the impeller required to spin it at the specified rpm.

Quote:
Also, what are the units on the 81500 constant? I only ask because my first pass at this has no bounds.
The units on the 81500 would have to be (rpm^2)/watt.

For example, to spin the impeller at 5000 rpm would require (5000^2)/81500 = 307 watts.

Hint: this problem has a closed-form solution, although you could just set up the equations and iterate rather than solve algebraically.