NanoSoft wrote:That is definitely the nicest turbo engin i have seen. To regulate fuel flow you can use a ball valve that is very small or a needle valve. Both work fairly well. For injectors i recomend oil burner nozzles. They give a very nice mist thats easy to ignite at low (10PSI) and higher (150PSI) pressures. Another source for nozzle is some farm stores. They sometimes have nozzles for sprayers that work fairly well too.
Seeing how you have two combustion chambers and two turbos all working in a circle. It will be a lot easier if you first start it on propane then switch it over to liquid. The reason is because diesel doesn't ignite very well unless it has a good mist and there is already a fire. Sparks don't work well unless the mixture is compressed like in trucks. Hope this helps.
Nanosoft
PS. How big are the inducers on your turbos and where did you get the design for the flame tube. It apears to have a lot more hole area then in most others.
I was planning to maintain use of LPG for startup purposes as it seems pretty necessary in order to get any liquid fuel to produce enough vapor pressure to begin combustion.
The inducers of these turbochargers is around 1.5" or so. The flame tube is 2.5" and the main combustor body is 4". Within the combustion chamber there is a liner to shield the flame-tube from the inlet air blast (as I was producing flame-out in initial testing and carbon deposits on half of the flame tube inner wall were indicative of a heavy rich condition caused by an imbalance of pressures inpinging on the flame tube).
THe flame-tube was just a shot in the dark. I have been noting excessive EGTs at around 15psi of combustor pressure and the instance that I turned the LPG tank upside-down and achieved a smooth 25psi for about 30 seconds I did not note the EGTs. It is fully possible that at these higher pressures the flame front is pushed back up into the flame-tube and the dilution air gets a chance to cool things off a bit.. *shrug* All I know is that I ran it for an amazing 30 seconds or so at 25psi and the whole rig was rocking forward and trying to move across the garage floor.. The best part was the fact that neither turbine burned up (which I have done before) so the EGTs must not have been too excessive. I will have to bring her back up to this level and note the EGTs to see if this flame-tube design is working properly.
I have seen a lot of mention that the flame-tube hole cross-sectional area should be closely matched to the inducer area of the compressor wheel, but I haven't seen any theoretical explanation as to why this is the desired geometry.. I'm more of a 'why' does it work kind of guy I guess..
I have also seen that a lot of people look for turbochargers with very high A/R ratios on the turbine housings for producing a lot of thrust. My question on this is: if you have a turbo-jet engine with a low A/R turbine housing AND with an afterburner unit installed, it seems the smaller housing is the most desired since a low A/R is going to create a larger degree of backpressure on the turbine which will hold more pressure in the combustion chamber. When the A/B is fired up, it expresses a backpressure on the turbine which causes it to slow (since the pressure differential before and after the turbine has now been lessened). By having a smaller A/R on the turbine it will experience less 'downspooling' when the AB is enabled and should maintain a higher flow of air through the engine. If anyone out there can confirm this or rip it to shreds, either way, I will be highly appreciative! :) It just doesn't seem to me that backpressure from the tighter turbine housing should cause the engine to necessarily put out less thrust IF and ONLY IF you are using an afterburner to augment the pressure differential on the turbine - then it simply comes down to how much airmass can you get the compressor to move. *shrug*
BTW, these turbos have a .63A/R turbine housing..
