Intake Diffusers

[macoovacany]

Hello,
I am looking for engineering information on inlet diffuser design. Specifically, angle versus length data for stable flow and maximum pressure rise and minimum drag and energy losses.

Regards,
Timbo

 

[pumpernickel]

Mr Macoovacany, howzit again?

There are many ways you can design one of these. It really depends what you want on the compressor face (I assume we're still talking PT-6), what your upstream conditions are and how many U-turns you have to put in the system.

Each one is different, depending on the application. I seem to remember something about internal angles in diffusers not exceeding ten degrees. But I assume they're of the 'nearly straight' variety.

Cheerio,
the scarlet pumpERnICkel

 

[macoovacany]

Hello Mr W,
Guy with a turbine Lancair is curious to know how much drag is coming through the powerplant system. Intake drag, diffuser thrust, exhaust momentum and pressure, stub drag, etc, etc, etc. Oh my.
Some people have more money than sense.
Old NACA report say max diffuser efficiency is around 75%, and drops dramatically with angle. Vanes extend the allowable angle to up around 20-25 degrees. How do you anti-ice vanes in the inlet? Too many penalties?

Cheerio,
Timbo

 

[ferdo]

Hi Mr. Macoovacany

Your inlet can be designed in many ways, as Mr. Pumpernickel already specified.

I think its a good idea to see the recommandations of P&WC in their PT6 Installation Manual. You will see also some diagrams regarding power loss, different solutions for different problems (including something about anti-icing vane) a.s.o.

Regards
Fernando