Flywheel Drive Torque

Mar 2016
3
0
How much Torque is required for a flywheel of (Inertia wk2=1500 lb-ft2) to accelerate upto 1500 RPM in duration of 80 Seconds?
The input drive is a Hydromotor with a displacement of 11.88 cu.inch per revolution.
 

topsquark

Forum Staff
Apr 2008
3,106
657
On the dance floor, baby!
How much Torque is required for a flywheel of (Inertia wk2=1500 lb-ft2) to accelerate upto 1500 RPM in duration of 80 Seconds?
The input drive is a Hydromotor with a displacement of 11.88 cu.inch per revolution.
What do you mean by "The input drive is a Hydromotor with a displacement of 11.88 cu.inch per revolution."?

-Dan
 
Mar 2016
3
0
The flywheel is rotated with an axial piston hydraulic motor.
Hydraulic motor piston displacement is 11.88 cubic inch per revolution
 

ChipB

PHF Helper
Jun 2010
2,369
294
Morristown, NJ USA
You asked how much torques is required to spin up the flywheel - this has absolutely nothing to do with what type of engine is used to create that torque.

The equation that governs torque and angular acceleration is T= I alpha, where T= torque applied, I = moment of inertia, and alpha = angular acceleration in radians per second squared. The angular acceleration here is equal to the final angular velocity (in rad/s) divided by the time it takes to reach that velocity. The final angular velocity in radians/second is 1500 RPM x 2 pi radian/rev x 1 min/60 sec. The only remaining trick to consider is that the value of 'I' that you gave is in lb_mass - ft^2, and once you do the math you will end up with torque in units of lb_mass - ft^2/s^2, which you will then have to convert to lb_force - ft by using the conversion 1 lb_force = 32.2 lb_m ft/s^2. I'll leave the math to you, but I suggest after you work this through you post back with your final result, and we'll be glad to check it for you.
 
Mar 2016
3
0
Thanks ChipB,

I worked out as you said and I got the final result as 5510 lb-ft. for 80 seconds.
Is it correct?
 

ChipB

PHF Helper
Jun 2010
2,369
294
Morristown, NJ USA
No - not correct. Show me how you arrived at a value for alpha - I'm wondering if you made a mistake converting the final angular velocity from rev/min to rad/second.
 
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