Designing a High Performance Two Cylinder Eccentric Circular Cam Piston Pump

[bigdogt33]

This is actually a homework question that i am confused about.

This is the question.
Design a two cylinder eccentric circular cam-type piston pump to deliver a flow rate of 0.65 m^3/s at a rotational speed of 110 rad/s. Let the stroke length equal the piston diameter and assume a volumetric efficiency of 75%. I need to find the stroke length and piston diameter.

Thanks for anyone who helps

 

[edgepflow]

Think about how to figure out the volume required per each stoke from the givin information. Then what is the volume of a "square cylinder"?

 

[bigdogt33]

i started by taking the 110 rad/s and dividing by 2pi to get 17.5 revolutions per sec. Then 1 stroke length per revolution which in turn gets 17.5 strokes lengths per sec to get shaft speed.

since it required a flow rate of .65, I divided that by 0.75 efficiency to get 0.867 m^3/s

then i divided that by 17.5 and set the whole thing equal to stroke length times the volume of the two cylinders.

Found the diameter and stroke length to equal 12.6 cm.

Is this correct or did i make a mistake?