[AR] Re: Parabolic Nozzle Approximation Function
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Fri, 2 Dec 2016 13:16:32 -0500 (EST)
On Fri, 2 Dec 2016, Graham Sortino wrote:
I was wondering if anyone could point me towards an example of how to
fit a function to G.V.R. Rao's parabolic approximation of a bell nozzle
given the initial angle and corresponding start point as well as final
angle and point?
This is actually fairly hard, because as Peter has pointed out, the axis
of the parabola generally is *not* along the nozzle axis. (Phrased
another way, the nozzle is not a piece of a paraboloid, obtained by
rotating a complete parabola around its axis -- the curves of the two
sides of the nozzle are not parts of the same parabola.)
<
http://www.adl.gatech.edu/classes/ae3021/ae3021_f06_9.pdf> used to have a
good discussion of this, but it's no longer there... aha, thanks to the
magic of the Wayback Machine, it's still available as:
<
https://web.archive.org/web/20090806205105/http://www.adl.gatech.edu/classes/ae3021/ae3021_f06_9.pdf>
Pages 11-15 describe how to derive the parabola from the Rao conditions.
Henry
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