Ideal exhaust dia based on size?
12-20-2012, 06:00 AM
#1
Ideal exhaust dia based on size?
Having a decent amount of experience with EDF I'm used to how critical inlet and exhast dimensions are to fan performance.
Is there a guide to size an exhaust pipe for a particular size turbine? Ie. can the pipe dia be the same for both a 100N turbine and a 140N class turbine?
In particular I'm looking at the ideal size on something in the 100-120N size. Ie, is 3.5" dia exit OK? can it be less/more?
Is there a guide to size an exhaust pipe for a particular size turbine? Ie. can the pipe dia be the same for both a 100N turbine and a 140N class turbine?
In particular I'm looking at the ideal size on something in the 100-120N size. Ie, is 3.5" dia exit OK? can it be less/more?
12-20-2012, 06:26 AM
#2
RE: Ideal exhaust dia based on size?
Sean
On a turbine you can "get away" with more than on EDF, but it affects temeratures and thrust. There are different types of turbine rated at around the same thrust, but with huge RPM differences.
The gap between turbine tail pipe and tube affects things too. (get RCJi's turbine Special and read Colin Straus's article)
3.5" 3.75" tube is about right for a 120N turbine. Larger pipes give good static thrust, but drop top end speed...but just a little
Dave
On a turbine you can "get away" with more than on EDF, but it affects temeratures and thrust. There are different types of turbine rated at around the same thrust, but with huge RPM differences.
The gap between turbine tail pipe and tube affects things too. (get RCJi's turbine Special and read Colin Straus's article)
3.5" 3.75" tube is about right for a 120N turbine. Larger pipes give good static thrust, but drop top end speed...but just a little
Dave
12-20-2012, 07:40 AM
#3
RE: Ideal exhaust dia based on size?
Thanks Dave, good feedback.
I do have the RCJI turbine issue and refer to it often as a nice apples to apples turbi e comparison.
I'm looking a new scale design that works out to about 6" dia inlet and right around 3.5" dia exit if true to scale size is kept.
Thanks, Sean
I do have the RCJI turbine issue and refer to it often as a nice apples to apples turbi e comparison.
I'm looking a new scale design that works out to about 6" dia inlet and right around 3.5" dia exit if true to scale size is kept.
Thanks, Sean
