d[Omega] A [root](b - a·b - a´)
-------- = ---------------------------, where A = --------------------. (11)
du (u - b)[root](u - a·u - a´) 2n
And the w polygon has a zero angle at u = 0, [oo], where [psi] changes
from 0 to m and back again, so that w changes by im, and
dw B m
-- = ---, where B = - ----. (12)
du u [pi]
Along the stream line xBAPJ,
[psi] = 0, u = ae^(-[pi][phi]/m); (13)
and over the jet surface JPA, where the skin velocity is Q,
d[phi]
------ = -q = -Q, u = ae^([pi]sQ/m) = ae^([pi]s/c), (14)
ds
denoting the arc AP by s, starting at u = a;
/b - a´ /u - a´
ch n[Omega] = cos n[theta] = / ----- / ------ (15)
\/ a - a´ \/ u - b´
/a - b /u - a´
sh n[Omega] = i sin n[theta] = i / ------ / ------ (16)
\/ a - a´ \/ u - b´
[oo] > u = ae^([pi]s/c) > a, (17)
and this gives the intrinsic equation of the jet, and then the radius
of curvature
ds 1 d[phi] i dw i dw / d[Omega]
[rho] = - -------- = --- -------- = --- ------- = --- -- / -------
d[theta] Q d[theta] Q d[Omega] Q du / du
c u - b [root](u - a·u - a´)
= ----·2n----- --------------------, (18)
[pi] u [root](a - b·b - a´)
not requiring the integration of (11) and (12)
If [theta] = [alpha] across the end JJ´ of the jet, where u = [oo], q
= Q,
/b - a´ /a - b
ch n[Omega] = cos n[alpha] = /-------, sh n[Omega] = i sin n[alpha]= / ------, (19)
\/ a - a´ \/ a - a´
Then
a - b·b - a´ a - a´
cos 2n[alpha] - cos 2n[theta] = 2------------ = ½ sin² 2n[alpha]------
a - a´·u - b u - b
[root](a - b.b - a´)[root](u - a·u - b´)
sin 2n[theta] = 2---------------------------------------- (20)
a - a´·u - b
[root](a - a·b - a´)
= sin 2n[alpha]--------------------;
u - b
2n c / b \ [root](a - b·b - a´)
----- ----- = ( 1 + ----- ) -------------------- (21)
[phi] [rho] \ u - b/ [root](u - a·u - a´)
a - a´ + (a + a´) cos 2n[alpha] - [a + a´ + (a - a´) cos 2n[alpha] cos 2n[theta]
= --------------------------------------------------------------------------------
(a - a´) sin² 2n[alpha]
Public-domain text, read in full here on John Shaqi.
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