Exhaust Augmenter Design Question


Well-Known Member
Oct 20, 2015
Aguila AZ
Can someone please direct me to some information and/or provide some advice on the topic of exhaust augmenter design?

I am very familiar with "injector pumps" and such because of my aircraft systems background however I have never designed one...until now.

The project is a bit off topic for experimental aviation because it is an RV project however the RV does take me to airshows and it lives at an airport so hopefully that is close enough.

I have built a sound enclosure for a portable generator and I want to use the exhaust blast to ventilate the box.

So specific to the exhaust augmenter tube, I need to figure out what is the best location for the genny exhaust pipe tip (how far into the augmenter tube should it be .

The exhaust pipe on the genny is 1 inch in diameter and the "cherry bomb" muffler exhaust pipe is 3 inch ID so I need to figure out how far into the 3 inch pipe the tip of the genny exhaust pipe should be. I think just 1 inch insertion should work because as the genny exhaust pulse blasts into the tube that burst will open up and expand like a mushroom as it transits the 3 inch pipe and that mushroom should drag a bunch of air with it through the "muffler". The cherry bomb has almost no obstruction just some perforated holes around the inside of the pipe so it should not provide much back pressure.

I know there has to be some great deal of design parameters of a real air injector system with the size difference between the inside pipe and the outside pipe and the contours of the shape of the tip etc so hopefully I can get the design close enough to produce some ventilation for the box.