Thread: Build Log A-7D Project
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Old Jan 19, 2012, 09:11 PM
JohnSH is offline
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Air flow adjustments

Dag; I have been silently following your B36 build and cannot fully express my amazement at you skill and audacity at even attempting such a project.

I think your A7D is just as brazen and I really want you to succeed at it. I was checking out your sketch of the A7D design and couldn't help but notice that you might experience some loss of EDF efficiency because of the uneven airflow pattern through your engine duct work.

At first glance, it appears that the air entering the two EDFs will be unevenly distributed and somewhat turbulent. The air exiting the fans will also experience some significant turbulence as it recombines to exit the exhaust nozzle.

Here is a sketch showing extensions to the inlet and outlet splitter vanes.

I would suggest that you do a wind tunnel mock-up study to fine tune the length and angle of the vanes. Find a way to measure the airflow through the two fans to equalize it and blow some smoke through the mock-up to study the turbulence and minimize it.

I doubt that it could ever be perfect but otherwise you may risk a significant loss of efficiency and thrust if you don't give it a try.
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