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Proceedings Paper

Simulation of laser propagation through jet plumes using computational fluid dynamics
Author(s): Markus Henriksson; Henrik Edefur; Christer Fureby; Oskar Parmhed; Shia-Hui Peng; Lars Sjöqvist; Jonas Tidström; Stefan Wallin
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Paper Abstract

We have investigated the possibilities of using Computational Fluid Dynamics (CFD) simulations to characterize the impact of refractive index fluctuations in a jet engine plume on Directed InfraRed CounterMeasure (DIRCM) system performance. The jet plume was modelled using both Reynolds-Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) formulations of Navier-Stokes equations. The RANS calculations provided a time-averaged description of the refractive index and the turbulence strength. The more computationally intense LES model provided time resolved data on large scale turbulent eddies within the engine plume. The smaller structures are assumed to be isotropic and are modelled implicitly to reduce the computational demands to levels feasible for current computational hardware. The refractive index data from the CFD calculations was integrated along the optical propagation path to produce phase screens. For RANS data this approach provided time averaged aberrations, whereas for LES data the temporal variation of low spatial frequency aberrations were available for a short time sequence. Modal descriptions of the phase screens were investigated to allow study of temporal variation at longer time scales. Alternatively the structure parameter (Cn2) can be estimated and used to provide order of magnitude approximations for the optical effects. The generated phase screens were used to calculate laser beam system level quality parameters including beam wander, fidelity ratio and power-in-bucket. The paper focuses on method development, but examples of a jet plume simulation showing that the engine plume turbulence has a significant impact on DIRCM system functionality are presented.

Paper Details

Date Published: 15 October 2013
PDF: 13 pages
Proc. SPIE 8898, Technologies for Optical Countermeasures X; and High-Power Lasers 2013: Technology and Systems, 88980E (15 October 2013); doi: 10.1117/12.2028339
Show Author Affiliations
Markus Henriksson, Swedish Defence Research Agency (Sweden)
Henrik Edefur, Swedish Defence Research Agency (Sweden)
Christer Fureby, Swedish Defence Research Agency (Sweden)
Oskar Parmhed, Swedish Defence Research Agency (Sweden)
Shia-Hui Peng, Swedish Defence Research Agency (Sweden)
Lars Sjöqvist, Swedish Defence Research Agency (Sweden)
Jonas Tidström, Swedish Defence Research Agency (Sweden)
Stefan Wallin, Swedish Defence Research Agency (Sweden)

Published in SPIE Proceedings Vol. 8898:
Technologies for Optical Countermeasures X; and High-Power Lasers 2013: Technology and Systems
David H. Titterton; Harro Ackermann; Willy L. Bohn; Mark A. Richardson; Robert J. Grasso, Editor(s)

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