metiz wrote:I thought fishmouths, on turbojets at least, were there to reduce noise and heat signature...
roland2001 wrote:i think one of these is close to what Luc is saying ---but i've heard of two different reasons 1st ) makes the engine much easier to "throttle" --as the "fishtail" is of varying lenghts depending upon where one might measures it at any given throttle setting 2) the "fishtail" helps to elliminate the "standing 1/4 wave" consequently reducing "back pressure" thus reducing the nearly ever present problem of reflux / regurgitation of high mass/heat combustion gases at/between the 2nd and 3rd conjunction of the intake / compressor stack------i use a "crown cut at the "tail" of the engine : 4 points as opposed to two points exhaust nozzle ---a thrust augmenter elliminates any and all regurg problems with this engine + makes for a significant increase in thrust , roland2001 PS: Hi Luc, kevin
roland2001 wrote:Hey Bro Luc , i agree absolutely with your comment---nice to see you still on board with the site and pressurejet project(s) take care, kevin aka roland2001
PyroJoe wrote:Thanks for all the responses.
I think my concept was lost though. In a perpenducular cut tail pipe there is typically a well distributed boundary that creates a vortex due to the exhaust gas exiting the port.
My thoughts on the fish tail is that it allows some exhaust gas to exit early while some stays partially contained. This should disrupt the boundry required for vortex formation, and allow ambient air to more quickly back fill behind the positive exhast wave, to allow it to shear away from the port without vortex formation.
Mental Picture:(Instead of the "donuts on a rope" contrails you should end up with broken ropes. maybe even unbroken rope if the frequency is high enough)
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