Multiphase Phenomena In Thermal Management Systems

The advancement of aeropropulsion technologies has placed increasing demand on the structural and thermal capabilities of high speed aeroengines. One solution to absorbing the high heat loads generated during chemical reactions is to use endothermic fuels in the cooling loops of these engines. At the temperatures and pressures likely to be encountered in the thermal management system of high speed aeroengines, the cooling medium will become supercritical in addition to undergoing thermal cracking and pyrolysis reaction. Advanced computational fluid dynamic (CFD) models coupled with fuel degradation chemistry are required to simulate the impact of fuel degradation in high speed aircraft cooling systems. This proposal involves the development a design tool for predicting the thermal stability of hydrocarbon fuels used in the cooling loops of high speed aircrafts, rockets and SCRAMJETs. In Phase I of this effort Combustion Science & Engineering (CSE) successfully demonstrated a reduced kinetic modeling strategy for jet fuels to predict the formation of gas, liquid and solid phase products as well as endothermic heat capacity at supercritical conditions. In Phase II CSE will further improve upon the models already developed and incorporate these in commercial CFD codes. BENEFIT: The product developed in this work will be a useful tool for supersonic and hypersonic vehicle design applications for the US Air Force. Furthermore, an important product from this project will be the development of a robust tool to be used in optimizing the design of thermal management for military and commercial flight vehicles. This product will give the design engineer much more freedom to test new designs operating with different fuels at wider range of operating temperatures and pressures. Discussions with engine design teams indicate that the capabilities of this project will greatly enhance current design tools in use by equipment manufacturers. Also the market for this product will include aircraft designers and manufacturers for both military and civilian aircraft. The use of this tool will significantly reduce development costs by eliminating some design iterations and hardware testing, which is quite expensive and time-consuming. This tool will be applicable to any system in an aircraft engine that utilizes fuel for thermal management of the aircraft. However, the capability to model chemistry-dependent processes, which is the focus of this work, is important to a variety of devices. This capability is potentially useful to other combustion systems, such as used in boilers or furnaces. These systems have traditionally been operated in a diffusion flame mode, but as the emission regulations have tightened, these systems are changing to more advanced combustion systems.