No fully opened nozzle Block 30, 40 and 50 when full afterburner
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Hello guys, again I’m appealing to your wide knowledge about the F-16
It has been an year since I’m active on falcon BMS but there is something I always noticed but never did anything about. It has come to my attention that the GE-powered F-16’s their nozzles don’t fully open when in full AB+the nozzle works different than P&W-powered engines. When idling inflight with a PW, the nozzle closes. When Idling with a GE, the nozzle opens. And with full mil the PW opens a little bit, like 10% and the GE goes to 90-100%
So why does this work like this ?
Thanks in advance everybody !
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Knowing the bit that I do about GE engines, it sounds to me like they got it right for GE ones…can’t say about PWs, but it doesn’t surprise me that they would behave different - the two engines have entirely different control/metering design implementations…particularly when it comes to the AB.
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I would be surprised that they are different. The reason to do open the nozzle is to do with thermodynamics as you need a divergent nozzle. The only thing that might be the case is that a fully open nozzle causes some issues with compressor stalls through the shock wave.
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Nozzle scheduling might be in section one of the dash one? Theres some public ones floating around, you could have a read and see if it is.
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As I used to work on afterburners professionally, I can tell you that the fuel flow in the GE one is continuously metered, and the Pratt one is metered in burner “segments” - the “improvement” from the original F100 to the latest was simply to move from five segments to seven; each segment is staged/ignited in accord with throttle position. For this reason I wouldn’t expect the control law for the Pratt burner to behave anything like the GE one.
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They are correctly simulated both GE and PW
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Here I started a thread a while ago about this, as I also was confused.https://www.benchmarksims.org/forum/showthread.php?12768-nozzle-indication-on-blk-50&highlight=nozzle
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