As best I can tell, liquid rocket injectors work because there is a heat source
that vaporizes the fog created by the injector (i.e., the combusting gases):
both are required to get vapor on vapor combustion.
Just making a fog of oxidizer at the head end of a hybrid motor will not
produce vapor, that requires heat.
Bill
Sent from my Commodore 64
On Aug 4, 2015, at 2:54 PM, Andrew Burns <burns.andrew@xxxxxxxxx> wrote:
Is there a reason while traditional like on like impinging injectors can't be
used to atomise and subsequently vaporise LOX or nitrous in a hybrid? Is it
something to do with getting the droplets to interact with the fuel boundary
layer?
Andrew
On Wed, Aug 5, 2015 at 6:37 AM, Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
wrote:
Mark:
It seems like an AN & ice water mix could be tailored to your temperature
goals. But why not go to a dry ice cooler and maximum density: a single pass
on a couple of coils should get you what you are seeking. LN2 is also
obviously an answer; both can be had in Mojave.
As Anthony has hinted, you will need a heat source at the head end to assure
the N2O fog is vaporized, otherwise combustion will be rough and unstable.
At Amroc we injected TEA throughout the burn to vaporize the Lox; I gather
VG is using Methane in the SS2 nylon motor.
Bill
Sent from my Commodore 64
On Aug 3, 2015, at 9:33 PM, Mark C Spiegl <mark.spiegl@xxxxxxxxx> wrote:
Wow... Im out of the office for a day and my inbox is full! :-)
Anyway.. Anyone who has followed my hybrid projects knows Im a fan of high
density Nitrous. Im looking to cool 20-50 lbs of Nitrous to 25-ish degF.
Goals:
(1) Flashing liquid to vapor to chill Nitrous is fine in a motor burning
10-20 lbs of Nitrous. Much above 20lbs (esp in the desert), flashing
liquid to gas becomes impractical. I would like to start a little closer
to my target temperature of 22 degF. The Peltier, Stirling Cooler, or
whatever would chill the supply tank, not the rocket tank.
I know ice is a quick-and-dirty answer, but I would like something a
little more elegant and deterministic. Bags of ice aren't a great answer
at FAR or Blackrock.
(2) I have had trouble igniting high density Nitrous in warm weather.
Cold weather is no problem. I cannot prove what is happening, but I
suspect temperature gradients in the long thin Nitrous tank are causing
the problem. If the Nitrous is 22 degF at the top of the tank, it may be
much much colder at the injector. Supplying Nitrous close to the final
temperature should help mitigate this problem, if Im correct.
A related question: Any simple ways to equalize temperature between the
top and bottom of the rocket's oxidizer tank???
--MCS
(Im an EE kind of person so my solutions tend to feel like electronics...
ie Peltiers)