Why is the sponge pads needed. Newbie

Hi Folks,

Planning a jet over a cliff edge for art project. I plan to light too.

The designs I have seen all had sponge pads at top and bottom of the straws.

If the straws are glued or fixed what is the purpose of the pad at the top?

I can image on the input side to even flow, but on the output side I thought it would make turbulence.
Thanks!

Eric

Most of the nozzles DO NOT have sponges on the top of the straws. Typically window screen or some other fine mesh is used there to hold the straws in place but that is all.

At the bottom the foam layer provides a slight resistance to the flow which causes the pressure to be even distributed across the entire cross section of the nozzle. Without the foam the flow from the inlet often ends up hitting some straws harder than other giving uneven velocity and causing turbulence in the water.

Hope that helps!