Post by lofi on Dec 24, 2016 6:21:30 GMT -5
Hello
I've been doing a little work on my first turbine project, which is going to be an external combustion chamber using propane, as it seems to be the simplest build. No pump, fuel ring or evaporators to worry about designing the FT around. I'll see how I get on with that before launching in to liquid fuel.
Anyway, like all the most interesting things in life, a bit of knowledge only leads to more questions... So:
1) Hole diameters. JetSpecs helpfully gives some defaults, but they don't vary with the inducer or derived FT size. Having read a load of threads, it seems that you can go too small or too large, even if the total area is correct. I assume this is relative to the FT size, so is there a calculable sweet spot, or is this an eyeball "that looks about right" affair?
2) Positioning. Obviously, there are three discreet zones. Is it as simple as putting the secondary holes half way along, and the primary and secondary at mid points between that and either end?
3) Pattern. From what I've seen, the trend seems to be for a zig-zag, diamond pattern, or at least some axial variation of the primary holes. Is there any rule of thumb for this?
The inducer of the turbo I'm using is 71mm - I've attached a drawing of my current FT arrangement. CAD link is here (free account possibly required, but it works in the browser with no software required.).
Thanks in advance!
Ian
And, of course: Merry Christmas!
I've been doing a little work on my first turbine project, which is going to be an external combustion chamber using propane, as it seems to be the simplest build. No pump, fuel ring or evaporators to worry about designing the FT around. I'll see how I get on with that before launching in to liquid fuel.
Anyway, like all the most interesting things in life, a bit of knowledge only leads to more questions... So:
1) Hole diameters. JetSpecs helpfully gives some defaults, but they don't vary with the inducer or derived FT size. Having read a load of threads, it seems that you can go too small or too large, even if the total area is correct. I assume this is relative to the FT size, so is there a calculable sweet spot, or is this an eyeball "that looks about right" affair?
2) Positioning. Obviously, there are three discreet zones. Is it as simple as putting the secondary holes half way along, and the primary and secondary at mid points between that and either end?
3) Pattern. From what I've seen, the trend seems to be for a zig-zag, diamond pattern, or at least some axial variation of the primary holes. Is there any rule of thumb for this?
The inducer of the turbo I'm using is 71mm - I've attached a drawing of my current FT arrangement. CAD link is here (free account possibly required, but it works in the browser with no software required.).
Thanks in advance!
Ian
And, of course: Merry Christmas!
Christmas came early for me, as a T6 flange, gasket and DC motor to drive the oil pump arrived in the post today! I wasn't expecting them until the new year. Sleeping won't be difficult - a few generous drams of scotch have taken care of that! Hope you have a great time with the family, and feel refreshed after the break ready to tackle the 12/118 into submission. Sure I'm not alone in looking forward to more insights that come out of the project.