Rear stagnation point

[xerj]

Yet again, this one has me puzzled.

I can visualise why the front stagnation point occurs, but other than saying
to myself "because it has to be at the trailing edge", I'm not grasping why
the rear stagnation point happens.

Can anyone elaborate? Most of the texts I find in searching basically just
say that it happens, not why, or at least not in ways that are making sense
to me.

TIA

[Scott Draper]

<<why the rear stagnation point happens.>>

I would expect it to be a consequence of the unfavorable pressure
gradient that occurs past the point of lowest pressure. The steady
deceleration brings velocity down to zero.

[Orval Fairbairn]

In article >,
"xerj" > wrote:

> Yet again, this one has me puzzled.
>
> I can visualise why the front stagnation point occurs, but other than saying
> to myself "because it has to be at the trailing edge", I'm not grasping why
> the rear stagnation point happens.
>
> Can anyone elaborate? Most of the texts I find in searching basically just
> say that it happens, not why, or at least not in ways that are making sense
> to me.
>
> TIA

It is the theoretical rejoining of the airstream, to result in
equilibrium pressure within the flow field. If it did not exist, the
aircraft would take the air with it.

I use it for cabin ventilation -- works like a charm!

--
Remve "_" from email to reply to me personally.

[Tony]

Think of it this way. The leading edge stagnation point is that place
where there's no 'wind' across that point on the leading edge: a little
higher and the wind flow is upward, a little lower, and it's downward.

Now think about the trailing edge. If you track air across the
surfaces, there will be a place where the upper and lower streams meet,
the flow vector is no longer along the sing, but directly away from it.


It also happens that on most conventional wings, the leading edge is
rounded so the stagnation point can more or less move up or down
depending on angle of attack. On the trailing edge the point is more
nearly a knife edge;

[Scott Draper]

<<If you track air across the surfaces, there will be a place where
the upper and lower streams meet, the flow vector is no longer along
the sing, but directly away from it.>>

That isn't a stagnation point. A stagnation point is where the
velocity is zero and static pressure = total pressure.