Mixing And Combustion Of Gel Propellants

ORBITEC proposes to analytically model and empirically develop the mixing and combustion of thixotropic gel propellants in the combustion chamber flow field generated by innovative vortex injection schemes. The new mode of propellant injection uses acombination of approaches. One approach was patented by the U.S. Army. The other approach, patent pending, was evolved by ORBITEC. In both methods the gels are injected circumferentially tangent to the chamber inner wall, inducing a swirling flow.Streaming the propellants on the wall provides required shear to keep the thixotropes liquefied to allow mixing and dispersion on the wall. The thin liquid film of propellants is vaporized and brought to ignition temperature by the adjacent swirlingcombustion. The ORBITEC method forms co-axial vortexes. The wall vortex spirals upwards, while the core vortex spirals down. One or more commercial codes will be used to model the injection and mixing of the thixotropic fluids. Propellant vaporizationand combustion in the flow field will also be modeled. Customized subroutines will be used to treat geometry variations, propellant alternatives, and to link the commercial codes. In Phase II, chamber hot-fire testing will validate the model.The nearterm goal of this modeling work is to provide for, and optimize, the use of gelled propellants in combustion devices such as rocket engines and air breathing propulsion systems. Gels may also find use in fuels for industrial gas turbines, and in oil-firedcentral power stations where gels may allow coal powders to be suspended in liquid fuels to lower costs of energy production. A verified model that optimizes gel engine designs will help to minimize the cost and development times required for advancedmissile propulsion systems. Systems using gelled propellants have the potential to replace solid rocket motor propulsion systems in many cases. The superior performance and control precision provided by gels greatly increase application flexibility andkill probability. Evolution of a common missile utilizing gelled propellants to replace several current single purpose systems would provide considerable cost savings to the Government. A common propulsion technology may also possibly be horizontallyintegrated into several existing systems, enhancing their performance and extending their service life while at the same time reducing cost. Gels are inherently more safe than liquid propellants because of reduced spill and leak potential. They alsovaporize more slowly because of their inhibited ability to disperse under gravity or surface wetting into thin films. This reduces the potential to release explosive vapor clouds. Gels are also of importance because of their ability to hold solidparticulate in suspension. This characteristic allows metal powders to be added to liquid fuels for greatly increased density impulse for volume limited rocket propulsion systems. NASA also has a demonstrated need for gelled propellant propulsiontechnology for booster and in-space engine systems where reliability, safety and low cost are paramount considerations. An interesting sidelight is that gels enhance space storability of propellants by reducing sensitivity to leakage, and by reducingslosh and migration of propellants in the tank at zero-G.