Divert airflow away from extended meltzone on Dragon HF.

[MartijnGevaert]

The main difference between the standard flow and high flow dragon hotend is the addition of a ceramic sock that increases the length of the meltzone. To fit this in, without making the hotend longer, the heatbreak is moved up a bit.
You can clearly see this in the images below for both the Phaetus and TriangleLab standard and high flow versions:

Phaetus dragon	TriangleLab dragon

Unfortunately, there is only a single dragon hotend mount which always blows over the entire hole. This works fine for the standard flow version, but for the HF version this means a section of the airflow is flowing over the extended meltzone.

Why does this matter?

There are multiple reports online of people complaining they have issues with PLA on the dragon HF, there are claims this is because they don't have enough cooling power on their heatbreak. Redirecting the airflow upwards towards the heatbreak would help with this.
It would also slightly improve volumetric flow and reduce power usage by the heater by no longer cooling the extended meltzone.

Proposed solution

There is already a project for the Afterburner that tackles this:

On the right side of the image, you can see that a simple lip would direct the airflow away from the extended meltzone.

Although the lip might need to have a shape like the image below to make sure that the air being redirected upwards doesn't block of airflow to the bottom part of the heatbreak on the high flow version.

(source: https://www.printables.com/model/68970-dragon-hotend-high-flow-fan-duct-phaetus)

[MartijnGevaert]

I had a quick go at what the design might look like. This is with the airflow redirection added:

And here's the original:

I won't share the step file because it's very rough/ugly. But this does show that it should be a relatively easy change, although I don't know the effects on airflow, except that it's probably safe to assume there will be less airflow over the meltzone.