The present work deals with numerical modeling of radiative heat transfer in absorbing, emitting, and anisotropically scattering media. The emphasis is placed on simulations of infrared radiation from aircraft engine exhaust plumes. The study considers methods for the solution of the radiative transfer equation and for spectral modeling of radiation. A review of the present-day literature on plume thermal emission is given. Radiative transfer equation solution methods, such as the ray tracing method, the discrete ordinates method, and the most modern finite volume method, are considered. With respect to the spectral simulation of high-temperature gases, state-of-the-art narrow-band approaches are overviewed, namely statistical narrow-band models and the correlated-k method. The most commonly applied technique in prediction of radiation signatures is based on a one-dimensional radiation calculation performed independently along each line-of-sight through the plume using a statistical narrow-band model. It is, however, well known that the statistical narrow-band models are incompatible with scattering by particles. Additionally, when scattering occurs, the radiation transport becomes three-dimensional. This situation is treated in practice by making various approximations to the full radiative transfer equation. A new infrared signature predictive technique is therefore proposed in the present research. The new approach overcomes the incompatibility of transmissivity-based band models with scattering and it can readily be applied to three-dimensional scattering problems. In this approach, the finite volume method is assumed to be used for the calculation of the radiation intensity field within the plume’s medium. In order to ensure an accurate modeling of gas mixture spectral behaviour, the narrow-band correlated-k model is coupled with the finite volume method. The finite volume solver implemented in this work is applied to the discretized radiative transfer equation in the primitive variable form and uses a marching technique that is consistent with the hyperbolic nature of the equation of transfer. The step scheme, which is unconditionally bounded and positive, is used as the spatial differencing scheme. Solutions for radiative heat flux and its divergence in three-dimensional enclosures containing participating media agree well with those available in the literature, thereby demonstrating the validity of the finite volume solver. A large number of calculations of directional infrared emissions from a realistic turbofan engine plume are carried out. A computer code named JERAD developed within the framework of the current work is employed. A comprehensive analysis of the calculation results is conducted to show that the proposed approach is capable of accurately predicting infrared signatures from absorbing-emitting-scattering jet exhausts.    «

The present work deals with numerical modeling of radiative heat transfer in absorbing, emitting, and anisotropically scattering media. The emphasis is placed on simulations of infrared radiation from aircraft engine exhaust plumes. The study considers methods for the solution of the radiative transfer equation and for spectral modeling of radiation. A review of the present-day literature on plume thermal emission is given. Radiative transfer equation solution methods, such as the ray tracing me...    »