Combustion chamber exhaust tube

[ckliever]

Hi all,

Question regarding the exit tube from the combustion chamber to the turbine side of the turbo. I’m in the design phase and I would like to know two things. 1: how critical is it to have the exhaust tube free of any obstructions? I ask because the turbine intake of my turbo is a rectangle with rounded corners which makes for a trickier fabrication than say if I made a simple rectangular connector with squared off corners. There will be some turbulence and resistance created as the air flows through the connector tube and into the turbine and collided with the rounded corners.

2; is it better to have a connecting tube from the combustion chamber to the turbine that is the same circumference from start to finish, meaning a smaller exit hole in the combustion chamber than the diameter of the flame tube, or is a tapered or conical connector that gradually reduces in size from the full diameter of the flame tube down to the diameter of the opening into the turbine the better way to go?

Thanks for the input!

Chris

[racket]

Hi Chris

Gotta have a tapered "funnel" between flametube cross section and turb scroll inlet , NO sharp edges or steps , its gotta be a smooth transition as the gas velocities are getting pretty high, so unfortunately it'll require that extra effort to get the right shape entering the scroll , jetandturbineowners.proboards.com/attachment/download/178

Cheers
John

[ckliever]

That’s what I needed to know! Thank you John!

[ausjet]

Here’s the one I made. I rolled a stainless cone that had the same outlet circumference as the turbine entry and persuaded it with a hammer and some heat into shape.

[racket]

Perfect :-)

The flametube always runs hotter than the flange so a rattly fit is fine , any minor bypass of air will only go towards cooling the scroll wall