The work at CRAFT Tech® often entails the analysis of jets/plumes for real aircraft and missile systems and thus the CFD methodology we employ is largely RANS based and CPU intensive. Aircraft simulations generally require analyzing the complexities system since aerodynamic interactions can have a first-order effect on the exhaust plume, and, since cycle information and internal mixing details must be part of the overall analysis. Aircraft jet/plume research is most often focused on jet noise reduction and IR signature minimization but there are many other real problems that we deal with such signal propagation through hot plumes (i.e. lasers to blind sensors on heat seeking missile which are degraded by density fluctuations) and varied ground effect scenarios (i.e. naval carrier landings and impingement concerns for VSTOL aircraft).
The missile jet/plume problems, while much simpler geometrically, involve thermo-chemical and multi-phase complexities that are still being dealt with at a fundamental research level. Tactical problems of current interest involve those of guidance and tracking for which there is a need to analyze the complete extended plume from launcher to target, so one can evaluate, for example, the degradation in signal caused by the particulates (i.e.Al2O3 from energetic solid propellants). Ballistic problems involve early detection for boost-phase intercept, and detection of staging events, all of which are plume related and may entail the analysis of missile plumes in a complex, dynamic environment. Interceptor missile design related to jets entails divert jet (large c.g. thrusters) studies which are complicated by the strong aerodynamic interactions producing a large separated zone upstream of the divert jet which is highly unsteady and produces large vibrations.
