Low-Altitude Plume Chemistry Signature Modeling

Infrared surveillance and tracking systems use intensity/temporal properties of observed missile signatures to develop information that assists in the typing and/or characterization of the target, a task of primary importance to boost phase intercept and other defense systems and activities. An important characteristic feature, afterburning cessation (i.e., the very rapid drop in the observed signature), has eluded modeling efforts to the present day. At lower altitudes (< 70 km), the turbulent mixing and combustion of unburned fuel with the atmosphere, or afterburning, and its shutdown with increasing altitude arise from the interplay of many processes that are not fully understood or have not been completely explored. Understanding the processes of afterburning and afterburning shutdown requires the very accurate prediction of the detailed thermo-chemical state of the plume gases to a finer level of accuracy than has been required in previous signature generation modeling. The purpose of this effort is to develop an afterburning model of sufficient refinement by including physics mechanisms previously neglected, employing the most recent combustion kinetics models, employing the most appropriate/efficient CFD codes, and paying particular attention to the numerical accuracy and convergence of the various numerical algorithms employed.