This came up earlier, with several mentioning motor length as
determining how high a metal particle fraction could usefully be
included in an APCP solid motor.
My thought then was that ratio of chamber volume to throat area should
be the main thing determining combustion dwell time of a particle within
a solid motor, analogous to liquid motor L* determining how much time
liquid fuel droplets have to combust.
You mention both volume and length as factors. Should I understand then
that solid motor length is also a factor, even beyond the strict matter
of how much it contributes to available combustion volume? IE, that a
long skinny solid motor would combust metal particles more completely
than a short fat one of identical internal volume?
And, out of curiosity, do solid motor designers even use L* as a design
parameter? Or some equivalent, or partial equivalent?
Thanks for the very informative discussion of metal particles, BTW.
Henry
On 4/9/2018 6:36 AM, Jim Rosson wrote:
Note-When using high levels of any metal, be aware that a motor needs sufficient chamber volume and length to allow complete reaction of metal powder into reacted molecules. Failure to have large enough space, will result in metal slag collecting on nozzle and/or burning in plume (creating lower combustion efficiency than expected).