#### vederstein

##### Must do dumb things....

- Joined
- Feb 26, 2011

- Messages
- 906

- Reaction score
- 724

Note that this is pure engineering at this point. Once I have some spreadsheet models to help guide me in the right direction, I'll get into the design process. At this stage I'm only doing an engineering analysis.

I've created three spreadsheets, modelling an air pump with 2, 3, and 4 cylinders. This analysis is just to see the optimal number of cylinders to produce an even airflow without an excessive number of cylinder. I modeled the output with some flow cutoff ±15° to ensure no crossing of ports between the piston inlet and outlet.

Let's take two cylinders, 180° out of phase. The air pulses are very pronounced. The average flow is 0.60, but the range goes from zero up to one.

Now let's look at three cylinders, 120° out of phase. The average flow is 0.92 with a pulse range of .29:

Now let's look at four cylinders with a 90° phase angle. The average flow is 1.22 with a pulse range of .45:

Given this analysis, I'm only looking for the smoothest airflow with the lease number of cylinders. Based on this, my air compressor pump will have three cylinders. I suspected this to be the answer, but now I have the analysis to back it up.

This is very early in the design process. This isn't really even design yet. It's actually engineering. This

*is*what mechanical engineering looks like.

That's enough for now.

...Ved.