Center for Reactive Flow and Dynamical Systems

Code 6410

The Center is responsible for the development and application of theoretical and numerical methods for the study of the fluid and molecular properties of complex dynamical systems. Current research in the Center focuses on applications of computational techniques to solve fundamental and applied problems in combustion, turbulence, propulsion, acoustics and flows inside and over ships and submarines; on molecular dynamics and quantum chemical approaches to the study of complex molecules.

Flame and Fire Dynamics

The detailed structure, stability and dynamics of a variety of flames and fires is studied using computational techniques that solve for the chemical reaction kinetics, diffusive transport of species, radiation and other heat losses in addition to the fluid dynamics. The work on flames in premixed gases has focussed on different mechanisms that can lead to instabilities and the resultant multidimensional structure. The effects of gravity and radiative losses from soot on flame lift-off and blow-off from burners has been investigated for diffusion flames. The transition to turbulence (shown in the Figure) and enhanced mixing efficiency of non-circular fuel injection nozzles is being currently studied. The interaction of a water-mist and other alternatives to halon on flames and fires is also being studied using the computational reactive flow capabilities developed in the center.

Advanced Propulsion System Concepts

Numerical simulations provide a cost-effective way to test and evaluate advanced propulsion system concepts. The use of shock-induced combustion and detonations to propel projectiles to very high velocities is being investigated. Basic issues such as the structure of detonations and the effects of premature ignition in the boundary layer of the projectile have also been addressed. Computational studies have also been performed of the combustion of high-energy fuels. The atomization, mixing and microexplosion of these new class fuels, which may be in the form of a slurry or as particles or droplets in a gaseous medium, need to be understood before their use in propulsion systems. The noise from propulsion system exhausts and means of controlling them with the use of flow modifiers are also being investigated with an emphasis on supersonic jets.

Flows inside and over Ships and Submarines

Developments in high performance parallel computing have made it possible to compute the unsteady airwake about the detailed superstructure of an actual ship such as the DDG51. The development of this software has opened up the possibility of predicting the spread of smoke or an explosion inside a ship. New developments in unstructured finite-element flow solvers have made it possible to simulate the launch of a torpedo from a submarine (see Figure). Better understanding of the launch dynamics is required for the safe and efficient launch under a variety of Naval warfare scenarios.

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Last modified: December 19, 1996

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