[vex]

Originally Posted by NoDOHC

Good call on the math error! I should have just given the original equation. Apparently the algebra is a bit rusty (I didn't think it looked right, but I couldn't find the formula solved for L in the book).
The natural frequency formula is correct though, I just checked it.

It happens to the best of us. I can't remember the times I've taken a test and screwed up some simple algebra and ended up with a horrible, horrible, horrible wrong answer.

Anyway, I like where you are going with this. Something to remember on the Plenum is that the two rotors are 180 degrees out of phase and have a 270 degree intake duration. This means that both rotors take in air at the same time.

That's actually really helpful, but I think we need to adjust the angle of intake and have it based off of port size, and what not as you're going to get a larger intake with a bridge port compared to a street port

Well my class is finished, time to get back to what I was doing.

This is looking good!

I like it a lot and I figure this will be an easy tool for other rotary (and heck, even them piston) guys to effectively make and design a proper manifold without the downfall of one too short or too long. If anyone is able I'd like to see someone make this into a web app that RCC can host on their page (I'll make a thread about it in lounge for those interested).

There are more advanced formulas for varying cross-sectional-area runners, but I don't have the ambition to enter them into paintbrush and you can probably find them online anyway without any errors.

I don't even know where to begin with that. Could you point me in the right direction?

If you want to do the math yourself, it is very simple to draw it up as a dynamic system and then find characteristic equations for it. I say this because you are most likely taking a course in dynamic systems right now or in the near future.

Actually I don't think I have any dynamic systems setup for my classes now or in the near future. This is why I'm doing a lot of it on my own. I can probably do something similar to what you're telling me in the schools CFD program (if I can ever get it running)

The Plenum has compliance as it acts as an accumulator. The runner has a resistance (dissipative) and Reluctance (inertial) element to it. The port closing is the disturbance function. The system is a lot harder with changing area.

You're going to have to go into more detail if you're going to make me want to understand what you're saying. I think I understand, but I'm not too sure.

Anyway, you will find that the wave intensity is a logarithmic decaying function and that the time constant is related to the runner smoothness (resistance) and the air velocity (inertia). I can't find the equation right now, maybe it is in a book at work.

If you ever come across it in the near future post it up (don't forget references).

I will try to find it and let you do the Algebra.

DEAL!