Pressure-Flow performance

[tikina33]

Hi, I have a pressure-flow performance for a motor blower. Its attached in the word document. As you may see, the pressure drops pretty fast at lower pressure whereas at larger pressure the pressure stays constant for a considerable amount of flow. My questions:
1. Why the pressure drops that fast for lower pressures and stays constant for larger pressures?
2. Why pressure increase intially for low discharge for 60 cm pressure curve?

Thanks in advance.
Tikina33

 

[chicopee]

That's the nature of the "beast"

 

[hydtools]

Typical centrifugal equipment performance.

What parameter was varied to create each curve? Does each curve represent performance at different speeds?

Ted

 

[tikina33]

Each curve represent performance at different speeds (RPM). The pressure was measured at the blower outlet and flow was regulated using a valve. The blower discharges air.

I am trying to know why in general the pressure remains constant for low discharge. As per theory the pressure should drop with flow. And also please, if you can answer to my two questions that I have asked. Thanks.

 

[BigInch]

It remains more constant at low flows because the head lost to friction from velocity (f * V^2) as the fluid moves through the blower is not a very big value. Essentially, there is no to little friction at those velocities, the velocities are slow and squaring a low number gives a low number and times k, is still a low number. As you move to the right, the velocity increases, friction increases by the square of the velocity, friction becomes a big number, hence our curves go DOWN at higher velocities.

"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.liv

 

[Strong]

The two upper curves do not look "normal" compared to the others. Possible reasons are: fan was running above design speed, test setup, or instrumentation. I would not try to make new fan laws based on that data. Is this a school lab project?

Walt