Roadrunner Kinetics Custom Reduced Mechanisms for CFD
Scramjet engines, which likely will provide the next generation propulsion capability, operate at extremely high temperatures and air velocities, conditions that are very difficult to reach in a laboratory environment. Facilities capable of testing these engines are limited in number and very expensive to run. A much more efficient approach to engine design is to employ reacting flow Computational Fluid Dynamics (CFD) to carry out combustion modeling to predict engine performance. The combustion of hydrocarbon-based fuels is a complex process resulting in detailed kinetic mechanisms typically containing hundreds of species and thousands of reactions to obtain accurate results over wide ranges of conditions. It is impossible to employ these full hydrocarbon kinetic mechanisms directly in a reacting flow CFD code due to unacceptably long solution times. To reduce computer time, simplified global mechanisms using severely reduced species sets and non-integer concentration exponents are commonly used. Unfortunately, these mechanisms are not accurate and can also introduce significant numerical difficulties and instabilities into the reacting flow CFD solution process.
Reaction Systems has developed a unique approach that we call “Roadrunner Kinetics” to reduce complex kinetic mechanisms, allowing us to identify and retain only the most important species and reactions. Roadrunner Kinetics has delivered proven speed-up factors of up to 200 times or more with respect to the initial full detailed mechanism while also preserving good accuracy as shown in our website presentation. This methodology is also very flexible in that it also allows us to retain selected minor species of interest such as NO and NO2?to model NOx?pollutant emissions, for example. Using this approach, we have developed reduced kinetic mechanisms for the combustion of fuels such as JP-7, methane, and ethylene with air as well as the hypergolic combination of monomethylhydrazine and red fuming nitric acid (MMH/RFNA). Moreover, “Roadrunner Kinetics” is automated to allow us to quickly develop custom mechanisms tailored for specific applications and conditions of interest at minimal cost to the customer.
Other Reaction Systems Projects
The development of weapons that can travel at hypersonic speeds is becoming a high priority to the US Air Force. A key technology needed for the continued development of these propulsion systems is the ability to cool the combustor by flowing fuel through channels machined in the walls.
Aircraft and missiles capable of rapid global strike and reconnaissance must fly at hypersonic speeds to achieve their performance goals. Future air-breathing hypersonic aircraft and missiles are expected to be powered by supersonic combustion ramjet (scramjet) engines.
The Army is very interested in accurate simulations of combustion in devices such as rockets and gas turbines, Otto and Diesel cycle IC engines, scramjet engines, rotating detonation engines, etc.
The surfaces of rocket engines are exposed to high pressure combustion products at temperatures up to 6000?F. Regenerative cooling can cause coke to form on the heat exchanger surfaces.
The development of new, robust, lightweight life support systems is currently a crucial need for NASA in order to continue making advances in space exploration, particularly in the development of Lunar outposts.
Reducing the allowable concentration of carbon dioxide (CO2) in spacecraft is a critical need for NASA.
Reaction Systems, Inc. has developed a new line of robust high temperature ceramic choked flow venturis for use in oxidizing and reducing atmospheres at temperatures up to 2700?F (1480?C).