High Fidelity Simulation Tools for Green Monopropellant Catalytic Thruster Degradation Mitigation and Performance Improvement

The U.S. Air Force is developing a catalytic thruster for advanced high density-specific impulse green monopropellants. The temperature and pressure generated in a green monopropellant thruster is much higher than with conventional hydrazine monopropellant, resulting in degradation of the catalyst. Therefore, developing and applying a model for predicting catalyst degradation and thruster performance will significantly reduce the cost of development of green monopropellant thrusters. Under this SBIR program, we will develop a transient computational model with fluid dynamics, heat transfer, and chemical reactions, and incorporate the effect of catalyst pellets (size, shape and internal diffusion) within the framework of a porous medium representation of the catalyst bed. This model will include various mechanisms that lead to degradation of the catalyst. The degradation mechanism will be validated and refined against the experimental results including transient pressure and temperature. In Phase II, the computational model will be extended to a two phase system allowing breakage of the pellet via over-pressurization to be modeled. At the end of this program, the physics-based computational tools will be used for monopropellant thruster design. BENEFIT: Development of the proposed technology will significantly help to achieve the IHPRPT Phase III objectives. The requirements of IHPRPT Materials working group (IMWG) include revolutionary materials and process technologies for advanced solid rocket motors, rockets used for boost and orbit transfer, spacecraft propulsion, and liquid boost and orbit transfer missions. Since the proposed technology is an integral part of these programs, its success will significantly benefit IMWG, and help achieve IHPRPT Phase III objectives. The members of the IHPRPT program, particularly DoD, NASA, Ultramet, Boeing Rocketdyne, ATK-Thiokol, Aerojet, and Pratt & Whitney Space Propulsion will benefit from the proposed technology. Some specific applications are: enhancement of the performance of space vehicles (NASA), and strategic, tactical and missile defense technologies of DoD. Potential commercial applications of the developed methodology include analysis and improvement of catalytic systems for pollution mitigation.