angled port

Hello everyone,
this summer, when i built my batchbox i was in a hurry, since i had only a couple of weeks to build it i haven't got any time to experiment, so during the construction i was wondering of various things, in particular i wondered  why the port needed to point to the center of the riser and not tangent to it.
Some weeks ago i went to a fair nearby me, there was a wood fired froling water heater on display ,  i took a couple of pics. Online you could find more of it.
Does someone already tryed to make a similar shaped port? also note the secondary air.