- #1
leviterande
- 106
- 0
Hi All!
See the picture.
A-Consider a flat plate physically moving perpendicularly through the air.
B-Consider this same flat plate sitting perpendicularly and stationary now in a wind tunnel where air is made to flow.
Accordingly if airspeeds, areas etc are similar, the 2 situations should produce the exact same results.
However, I am interested in comparing only the rear wake drag in the two situations.
In situation A, if I understand correctly, main cause of the rear wake drag comes mostly from the the air being displaced ahead by the moving plate thus creating and leaving a rarified partial vacuum area behind the plate which wants to suck air from top/bottom side of the plate which results in the negative drag pressure i.e. wake drag on the plate.
Now, in situation B, the air coming from the front is similarly hitting the front of the plate and similarly basically not easily allowed to pass behind the plate. BUT!, in situation B there is still ambient air behind the plate, i.e. there is no rarified air or partial vacuum behind the plate because the plate in sitiation B hasnt physically displaced any air mass, right?
I thought perhaps too much about this issue which may have led to this very unintelligent question, still I would love to have clarification.
So, are the wake drags of A and B yet exactly equal? If so, may you explain how the -identical-to-A- wakedrag of B is caused?
Thanks
See the picture.
A-Consider a flat plate physically moving perpendicularly through the air.
B-Consider this same flat plate sitting perpendicularly and stationary now in a wind tunnel where air is made to flow.
Accordingly if airspeeds, areas etc are similar, the 2 situations should produce the exact same results.
However, I am interested in comparing only the rear wake drag in the two situations.
In situation A, if I understand correctly, main cause of the rear wake drag comes mostly from the the air being displaced ahead by the moving plate thus creating and leaving a rarified partial vacuum area behind the plate which wants to suck air from top/bottom side of the plate which results in the negative drag pressure i.e. wake drag on the plate.
Now, in situation B, the air coming from the front is similarly hitting the front of the plate and similarly basically not easily allowed to pass behind the plate. BUT!, in situation B there is still ambient air behind the plate, i.e. there is no rarified air or partial vacuum behind the plate because the plate in sitiation B hasnt physically displaced any air mass, right?
I thought perhaps too much about this issue which may have led to this very unintelligent question, still I would love to have clarification.
So, are the wake drags of A and B yet exactly equal? If so, may you explain how the -identical-to-A- wakedrag of B is caused?
Thanks