E3D Fan Duct Improved Flow

** Update**
In an effort to improve this via testing, I have found it increases airflow by a huge 2% yeah hardly worth it also I suspect the airflow may be concentrated through smaller areas of the heatsink reducing the overall effectiveness.
The 5th iteration (E3Duct V5) seems to make an improvement to cooling, input from others has helped derive this design. There is still a way to go, print it and try it out if you find a way to test the effectiveness please share the result.

In an effort to build a quieter and better machine, I looked at the E3D fan duct, I am using a genuine E3D V6 24V hotend and the 30mm fan is the noisiest part after doing stepper driver upgrades. My thinking was to improve the airflow and then reduce the fan speed to reduce noise and improve longevity of the fan. These axial fans tend to reduce their flow rapidly when the airflow is restricted the fins on the E3D hotend provide enough restriction to greatly reduce airflow while the fan worked hard. After adding the second set of stationary fins in the duct I found the airflow increased substantially. If you compare this duct with an original without the heatsink in place I could determine little difference except a little more noise (a step backwards you may think) however if I clipped in a heatsink the airflow was considerably higher than the original. Now you can make a choice, improved cooling or slow the fan and if you find the balance both reduced noise and improved cooling. I have arranged the internal fins to align with the fan motor spars since these will likely be causing some turbulence and try not to introduce any more also the reason for only 3 fins, having 6 fins I think will only increase friction and give no more improvement.

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