Flame on exist nozzle

[Alex Chan]

Recently, I pursade a KJ-66 motor with a Pro-jet Eagle ECU. As I increase the throttle abrustly. A flame notes at the exaust nozzle. If I keep on increase the throttle, the motor will turn off. To prevent flame out, I simply reduce the throttle 1~2 second, and increase the throttle slowely.
(default setting: acceleration delay 7.5s, deceleration delay 3s)
I'wd be glad if anybody help to solve the problem.
Best regard,
Alex Chan.

[steel]

Hi,
I believe your turbine could self sustain at idle, but exit nozzle give off whitish blue flame when you throttle up. If you do a quick ram up to max throttle, the flame (white) will be very pronounce and the engine will be alot of noise. I am having such problem too. I suspect the blue whitish flame is from unburn fuel that is outside the combustor. I am still trying to solve this. maybe you are not alone.

[Johansson]

There is really nothing to be solved, the reason why flames comes out of the back of the engine is because the quick increase in throttle lets more fuel into the combustion chamber and if the engine don´t spool up quickly enough the air/fuel ratio gets way to high. Then the fuel that haven´t been burnt inside the combustor burns outside it, and there is the reason for the flames...

//Anders

[Fricke]

Hi Alex -

What You need to do is to adjust the ECU - the ramping of the fuel. What happens is that the engine gets to much fuel. There should be a chapter in the Manual for the ECU that describes how to adjust the ramp time for the fuel pump. And have a look on the internet for people that use the same ECU for the same engine - and contact them to get the correct settings for it.

//Fredrik - That just happens to know stuff... =)

[steel]

Hi there,
I fabricated a few combustor (3 pcs). I uses sheet of 316 steel and a lot of fixtures to weld them up. As my process of making them is the same, the 3 pcs of combustor are identical to the naked eye. (those holes were laser cut). However, while running on the same engine assemblies using the same ECU setting, 2 of the combustor give same results (hi EGT, bluish flame). only 1 pc give low EGT, no bluish flame good thrust ratio.

I find that by enlarging the dilution holes on the internal annular area will help in decreasing the EGT, but did not solve the bluish flame thingy..

those combustor with bluish flame was observed to have burn mark far away from the front wall of the combutor liner. (about a half combustor body length away from the front). the one which is good was seen to have burn mark almost on the entire body. How do I make the flame to burn "deeper" inside the combustor liner?

I still wonder why... :?:

[multispool]

Hi Steele,

You are experiencing late burning due to incorrect fuel/air mixture in the primary zone (front end).
Check for leaks between the front plate and the two wrappers!
Can you post a pic of the burner?
What are the hole number/position and size at the front end of the chamber?
What size and angle are the swirl jets?

Alex,
Try an acceleration delay around 25 and decelleration delay around 30. Note These numbers are not secs but a setting in the Pic controller in the range 0:255

As Fricke said, the idea of the controller is that when someone slams the throttle open the controller takes over controll to avoid flame out and very high temps

[Fricke]

First: What engine are You building?

Second: Try to contact the designer of the engine, or try to find a forum on the net about Your particular engine.

Third: I have no experience with the R/C type of turbine engines, but what You describe sounds like the two chambers are wery different than the one that burns with a "whitish flame"??
Pictures is a good thing to show. That way it´s perhaps easier to spot the problem.

Fourth: And are You using the chambers on the same engine?

//F

[Alex Chan]

Dear guys,

The problem seem to be solved as I increase the acceleration delay,and also change a smaller pump.

best regards,