Originally Posted by PeterVRC
There 'must' be more pressure in a CS!0...
1)They give less 'thrust' (LOL) than for equal power in a low blade count fan.
2) They 'hate' exhaust restriction, more than a low blade count fan (because the air density/compression is already higher and causing more strain)
3) They demonstrate more 'pulling power', but less speed. Even though their benched thrust is lower than the low blade count fan.
So there must be a REASON for that.
And those results gives clues as to where it fairly surely must come from. The pressure... and thus air density being higher in their exhaust, than in a low blade count fan.
Low blade count is like putting your finger over a hose to get a faster flow.. narrower, and 'stronger' in that thin stream, but very weak (zero) outside that small stream. Thus the pressure in the housing/ducting is lower overall... but the airspeed is higher.
High blade count is just the full hose sized stream.... especially a CS10 which covers over 90% of the swept area
I don't really care about the MATHS, because you can twist and turn all kinds of formulas to suit any thoughts..... but often there are MORE aspects (formulas) to ALSO include, if you want to totally true answer - but someone truly knowing it ALL can use the correct maths and ALL the formulas that apply. Bernouli this, Newton's that, don't mean much if you LEAVE OUT other truly critical factors.
But you don't need to 'know it all' to be able to see when there is something missing in maths supplied.
Again blade count means absolutely nothing. Rotor blade shape is everything. The aspect ratio leads to flow problems at the blade as pressure rises and I am talking about slight pressures this is why the fan does not like outlets less than 85% FSA.
Peter if you dont care about math and physics you cant really give an intelligent answer to any real question as math and physics permiates all of what we do!
School me on what I left out?
PS: I look forward to seeing more of your posts, in fact I will give you the next 20 hours to come up with something in rebuttal but beware I will use math and physics in my defence.