If using peroxide, wouldn't a catalyst bed serve to produce oxygenated steam?
That has been the usual solution for peroxide hybrids....
Bill
Sent from my Commodore 64
On Aug 4, 2015, at 4:34 PM, Lloyd Droppers <ldroppers@xxxxxxxxx> wrote:
Andrew: You certainly can directly inject liquid into the head end of a
hybrid make it work, but something like a traditional nitrous injector only
works because they function by the nitrous flashing to vapor on injection so
you need some way to vaporize the liquid. To vaporize the liquid you need 2
things: small droplets and time. A impinging injector will work to create the
small droplets, but you might also need to add a precombustion (to give the
nitrous time to vaporize before it hits the fuel) and postcombustion chamber
(to make certain that any vapor that made it through has time to combust) for
it to work well. This obviously comes at the cost of a larger motor, and
Bills suggestion of injecting a fuel or TEA would also work to assist
vaporization at the cost of some complexity.
A few years ago I did some work on peroxide hybrids (25-1000 lbf) and we used
commercial spray nozzles for atomization and a small post combustion chamber
and we didn't notice much if any combustion instability.
http://www.responsivespace.com/Papers/RS4/Papers/RS4_4004P_Tsohas.pdf
Mark: Ice is totally reasonable at FAR and is probably the best. The Jawbone
Canyon store is only about 15 miles away, and sells ices by the 20 lb bag.
Otherwise for the temperatures you are looking at if you wanted more of a
turnkey solution there are freezers for RV's and car camping that run on 12V.
They usually are rated to get to 0F and cost about $300 new. Just make sure
you search for a compressor freezer so you don't buy a peltier refrigerator
instead.
Lloyd
On Wed, Aug 5, 2015 at 6:54 AM, 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)