mixture ratio varies over the firing due to the increasing surface area of
the solid fuel.
Why? Solid rockets are configured with neutral burns, a finocyl is close
but there are better ones and the liquid injectant can be throttled to
tailor O/F even like a TRW variable geometry pintle.
K
On Thu, Jan 14, 2021 at 6:54 AM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Jack:
Unlike liquid or solid motors, there is no explicit solution to the sizing
of a hybrid combustion chamber and nozzle. This is because the mixture
ratio varies over the firing due to the increasing surface area of the
solid fuel.
Thus one has to build a dynamic model that solves for all the relevant
data in time steps and then adjust the flow rate and nozzle size to maximum
performance (average Isp, typically) over the burn time.
You will have to start w/ a oxidizer flow rate and nozzle throat and exit
area and then estimate, by time step (I use 0.01 seconds minimum) the fuel
area and instantaneous regression rate, the resulting mixture ratio, the
pressure and thrust and the Isp, Then proceed to the next time step,
accounting for the increased surface area of the solid fuel.
The average Isp across the full burn can the be maximized by adjusting
flow rate and nozzle sizing.
Bill
On Wed, Jan 13, 2021 at 7:25 PM Jack Hanna <jackhannaofficial@xxxxxxxxx>
wrote:
Thanks, I was more curious about the nozzle / flow rate calculations for
rough use so that I can design a schematic