Tim,
You have given me a few ideas to check on.

James,
As far as I can tell, that concept is only useful on vehicles with really bad injector design. It isn’t really useful on newer vehicles with better designs. The flow rate on rockets is such that the device wouldn’t have time to do it’s trick.

Several contracts activated a couple of weeks ago which put me to the six day week of pushing instead of the short weeks of the last several months. These idea posts will be infrequent as long as the push is on. Happy holidays all.

Speculatively, I wonder if there is some benefit in injecting the fuel right at the throat, as is done on the vortex engines. This might allow you to direct some of the flow down the nozzle to both cool the nozzle and provide some thrust augmentation. This would of course create many many concerns that need to be addressed.

I suspect that you can get around the positive feedback problem if you enrich the flow with the propellant that has the higher evaporative rate. If the chamber gets too hot, the mixture enriches and cools; if it get too cool, the mixture goes towards stochiometric and heats up. I suspect that increasing chamber pressure will reduce the rate of evaporation to provide a bit of negative feedback as well, but my thermodynamics is a bit hazy in this area.

One final tangent, how insulative is RP-1? An old idea I had was to wrap the kero tank around the LOX tank. This gives you less surface area to insulate (if any), and a less sticklike LV. Problems are heat transfer from the LOX to the kero (you might get around this by prechilling the kero), and probably higher tank weight.

http://www.greencarcongress.com/2008/09/researchers-fin.html

Seems like it should provide the same kind of improved combustion efficiency that it does in ICEs, and it would not require much more than wrapping a coil around the fuel and oxidixer input lines.

jak

I believe liquid kerosene and liquid oxygen together are well below ignition temperature and the different densities will tend to keep them separated for the few milliseconds in question. As the temperature rises, they boil off into the combustion zone before ignition.

Mixing is a serious problem in rocket engines. The basic problem is that large volumes of propellants must be mixed in a few milliseconds.

Gas phase mixing is a problem, if at reasonable pressures, because the volume flow is large. Liquid phase mixing leads to a dense explosive. Gas/liquid mixing seems best. I think the shuttle has many annular injectors that inject liquid oxygen droplets at low velocity surrounded by a fast-moving stream of hot gaseous hydrogen. The oxygen evaporates off the surface of the droplet and mixes with the hydrogen in the turbulent wake of the droplet.

An Injecter provides negative feedback, IE if the chamber pressure increases the injectors flow less…..this has positive feedback more
energy more boiling more energy etc…..
Leading to an ungodly heavy chamber or Rapid unplanned dis assembly.