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Chemical and Physical Mechanism Processes for Propulsion Related Signature Events



TECHNOLOGY AREA(S): Air Platform, Information Systems, Sensors, Space Platforms

OBJECTIVE: Extend capabilities of existing, propulsion-related signature tools to characterize emission phenomena over a broad portion of the electromagnetic spectrum, from ultraviolet (UV) through the long-wave infrared (LWIR).

DESCRIPTION: State of the art propulsion related signature models include exhaust plume phenomena observed in the short-wave through mid-wave infrared portions of the electromagnetic spectrum. Missile defense applications would benefit from increased capabilities in the form of more accurate signature characterizations across a wider region of the electro-optic (EO) spectrum from the UV through LWIR. The general suite of propulsion-related signature modeling tools (which include 2-D/3-D computational fluid dynamic codes, Direct Simulation Monte Carlo models and radiation transport solvers) provide the basic framework for flow-field and signature generation, but do not contain the underlying chemical and physical mechanisms and processes to properly account for all spectral emissions. The driving phenomena in these band regions (e.g. particle optical properties, molecular band model parameters, molecular collision cross-sections, and quenching/excitation mechanism pathways) are not well established or characterized. Passive signatures in these wavebands have been measured in data collections from many flight tests as well as other past DoD-sponsored missions, but the ability to model these observations accurately needs improvement. The emission phenomena include all EO features that may be observed passively through the entire missile flight envelope, from launch through boost phase to impact, that are generated from associated propulsion subsystems or other related phenomenology. While not comprehensive, the list of relevant propulsion events to be examined across the UV to LWIR bands includes: boost phase plumes for all types of propellant systems; propellant fuel and oxidizer venting; particle trails; and solid rocket motor chuffing. Event observables include molecular and particle emission and scattering.

PHASE I: For one propulsion-related signature event observable of interest, identify the chemical and physical phenomena needed to model, and properly account for, the complete process (from propellant combustion through signature emission); and, prioritize the importance of each component as a function of altitude, velocity, and spectral band. Finally, select one important complex component and demonstrate an innovative methodology (theoretical or experimental) to solve for that component unknown. If possible, demonstrate this complex component upgrade within the existing government propulsion related signature tools. Maximum practical use of the existing government propulsion related flow-field and signature framework is desired to reduce both development and validation costs.

PHASE II: Identify additional signature processes and other pertinent phenomenology needed to model propulsion-related signatures in the alternative bands. Demonstrate these new or updated code modules, chemical reaction, and/or physical process databases within the existing suite of government propulsion related signature models. Further, maximum practical use of available plume software is desired to reduce both development and validation costs. Deliver all demonstrations, upgraded software modules/databases, technical documentation, and validation to the government for independent test and evaluation.

PHASE III DUAL USE APPLICATIONS: Transition advanced methodology into existing signature models used to support government elements. Apply software to a variety of missile defense sensor and missile interceptor systems as well as other problems of interest to the government.


  • Simmons, F.S. 2000. “Rocket Exhaust Plume Phenomenology.” AIAA. Reston, VA.
  • G. Sutton and O. Biblarz. 2001. “Rocket Propulsion Elements.” Wiley Interscience. Seventh Edition.
  • S.F. Gimelshein, et al. January through March 2002. "Modeling of Ultraviolet Radiation in Steady and Transient High-Altitude Plume Flows." Journal of Thermophysics and Heat Transfer. Vol. 16, No. 1. 58-67.
  • V.R. Tagirov, et al. November through December 2000. “Atmospheric Optical Phenomena Caused by Powerful Rocket Launches.” Journal of Spacecraft and Rockets. Vol. 37, No. 6. 812-821.
  • C.E. Kolb, et al. July through August 1983. “Scattered Visible and Ultraviolet Solar Radiation from Condensed Attitude Control Plumes.” Journal of Spacecraft and Rockets. Vol. 20, No. 4. 383-389.
  • N. Gimelshein, et al. January 8-11, 2007. “Numerical prediction of UV radiation from two-phase plumes at high altitudes.” AIAA Paper 2007-0114. AIAA 45th Aerospace Sciences Meeting and Exhibit, Reno, NV.

KEYWORDS: plumes, boost phase signatures, high altitude, ultraviolet, visible, near-infrared, long-wave infrared, computational fluid dynamic, Direct Simulation Monte Carlo, particle optical properties, kinetic rates, collisional cross sections, two-phase flow; reacting flow

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