Bellmouth design

[AleksS]

Does anyone know of any methods for designing a bellmouth? Are there certain design constraints? ie. the radius is equal to half the radius of the inlet tube. Thanks for the help.

 

[JeanAlesi]

What is a bellmouth?

 

[AleksS]

Sorry, I was a little unlcear. Its the top part of a velocity stack on the intake. Here is a pic

http://www.todaracing.com/images/engine_toyota_4ag_b.jpg

Its meant to smoothen out the airflow into the engine. Its also known as a trumpet (for obvious reasons). Hope this makes things a little clearer.

 

[sciguyjim]

I remember reading once that, ideally, the "bell" should do more than just curve away from the mouth of the intake, as seen in the photo you referenced. I read that the optimal shape is for the edge of the "bell" to curl back on itself rather than simply stop in mid air. I'll try a (greatly simplified) drawing...

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[chasbo]

The design of the bellmouth affects its design parameters. One for a jet engine intake is designed differently than one for a ducted fan. There is an inlet section, but ducts with bellmouth entrances also can either have a straight discharge, or can taper inward or outwardly.

What do you plan to use it for?

Chasbo