Basic Diffuser Design Assistance

Moderator: Mike Everman

Post Reply
Posts: 22
Joined: Mon Feb 27, 2006 2:12 am
Antipspambot question: 0
Location: Iowa

Basic Diffuser Design Assistance

Post by airrocket » Wed Apr 02, 2008 5:09 am

Are there some basic KISS ratios, calculations, or formula's to aid in estimating the relationship between diffuser expansion (inlet to outlet CS area ratio) and degree, percent or ratio of pressure (density) rise, temp rise, velocity decrease, across the diffuser section? I've searched the internet for days with no luck. All I find are pages and pages of formula’s relating to boundary layer thickness, turbulent, laminar flow etc... most based on wind tunnel test. I need a Basic Diffuser Design for Dummies book!

After reviewing NACA ram jet design I question some of Decker's information. It might suffice for static weed blower ram jet designs however I questions its validity for actual high speed flight applications.

Retro Flight

Posts: 83
Joined: Fri Oct 24, 2003 9:35 pm

Re: Basic Diffuser Design Assistance

Post by Stuart » Fri Jul 18, 2008 10:22 pm

What you are looking for are the one-dimensional gas flow equations. While they are algebraic, it can still be a bear to get out what you need once you couple in a inlet diffuser to exhaust nozzle and add in combustion. I've been working on it for a while.
I'm writing an automated airplane designer in java, useful later when you guys get ready to bolt a p-jet onto some wings

Post Reply