Power Calculation of Hydraulic Rotators 3

[Startto]

What is the formula to calculate Power(Kw) and Rpm of a hydraulic rotator (Vane model) from Torque 900 Nm, Displacement 330cm3, flow rate 14 L/min, volumetric efficiency is 0.9?

 

[EngDesServices]

Power (W) = Torque (N.m) x Speed (RPM) / 9.5488



Michael Hall, PE (TX) PMP - President
Engineering Design Services LLC

http://www.engdess.com

 

[hydtools]

Rpm = flow rate/displacement per rev

Ted

 

[Startto]

@EngDesServices
Hello Friend,
Thank you so much for your kind reply.

But I see some faults in the formula when tested with my model.

When I tested the rotator with flow of 14l/min, RPM was 42.
So Power (KW)= (900*41)/9.548
= 3864.68 KW
= 5178.67 HP.
I think the constant should be 9554 instead of 9.548?

 

[Startto]

@hydtools
Hello friend,
Thank you so much.
As per your formula,
RPM = 14/0.33
= 42.42 RPM
Stays closer to the practical result of 41 rotations.


Do you have any Idea how to find power from the values provided in my question?

 

[hydtools]

Startto,
The constant is 60/(2pi) = 9.9453

Ted

 

[Startto]

@hydtools,
Hello Friend,
I understand the concept behind 9.9453
But look the answer 3864.68 KW.
I am sure this power is not technically possible.
Please correct me if I am wrong

 

[cdill21]

Startto,

What model pump are you looking at?

 

[MintJulep]

Newton * meter / s --> Watt. Not Kilo Watt

 

[Startto]

@cdill21
Hello,
Its a Vane motor

 

[EngDesServices]

Hey Startto,

I edited my post to reflect Watts as opposed to kW, guess I wasn't paying enough attention the first time around. Sorry about that.

Power is simply the work done per unit of time or P = W/dt.

A watt is 1 joule per second which is equivalent to 1 NM/S.

So to get power in Watts, you are going to want to find out the amount of work performed in 1 second.

Using HydTools equation for RPM with your input values of 14L/min and 330mL displacement per rev and 0.9 volumetric efficiency gives roughly 38RPM.

To use RPM in the final equation, you need to convert it to angular velocity - which is where the 2*pi/60, or 9.549 in the formula comes from.

Putting it all together leads to: 900nm * 38RPM / 9.549 = 3,581.5 Watts or 3.58 kW or 4.8 hp.

Hope that helps.

Michael Hall, PE (TX) PMP - President
Engineering Design Services LLC

http://www.engdess.com

 

[Startto]

@EngDesServies,
Hii friend,
There is no need to be sorry, It happens.
But really thank you , yes it does helps.