power turbine - rocketmotorman

rockstar17 · Post by **rockstar17** » Mon Sep 24, 2007 3:26 am

hey rocketmotorman its me again. haven't started work on the project yet, but hopefully I'll start gathering parts for it soon. Im stoked.

anyway, just thinking ahead.....could you show me a simple diagram or explain your setup for getting the exhaust gases to flow over your allison 250 power turbine on your jet bike? I was thinking a pipe that expands off of the turbo's turbine to accelerate the gases, then just feeds the gas head on to the turbine, maybe around the edge of the blades somehow.

also, if you had a turbocharger with a turbine outer diameter of 2.2 inches, would a power turbine with an outer diameter of 5 inches be adequate to extract power?

also is the 3rd stage turbine wheel in an allison 250 a larger turbine or a smaller one?

do you have to use a stator blade?

thanks for any info!!!

racketmotorman · Post by **racketmotorman** » Fri Sep 28, 2007 5:59 am

Hi
Pics here
http://www.ivcity.com/john/index.html

If you direct your turbos efflux directly (axially) at an axial turbine wheel , you'll need a set of nozzle guide vanes (NGVs) to turn the gases to meet the wheel at an angle of ~20-30 degrees to the turbine disc , as well as expand and speed then up .

By using a hybrid scroll setup on my axial turbine wheel , I was able to get the angle without the need for a full set of NGVs .

If the freepower turbine has flow passageways twice the area of the flow passageways in the tubos turbine , it should be large enough for a freepower turbine , its a bit more complicated than this simplification , but good enough for you not to get into trouble :-))

The Allison third stage wheel is ~180mm in dia

Cheers
John