Part 1. All vehicles emit IR radiation of different wavelength and intensity. For military vehicles a low IR signature is usually an important design parameter. By computing the IR signature, factors contributing to the signature can be determined and minimized. The IR signature is computed by applying a radiation model to the results of a fluid mechanics computation. In the present study a converter has been created to connect the radiation code SIGGE to the simulation software package FOAM, used for the fluid mechanics computations. Finally, this system has been applied to an engine configuration from VAC and the IR radiation has been computed. Part 2. With a gelled fuel the risks while handling the fuel decreases, and it gives the possibility to add energetic solid particles. Initial studies have been performed were the high density fuel JP-10 been gelled. Rheological studies have been conducted on the gelled fuel and it showed good gel strength at 7.5 weight percent gelling agent, Cab-O-Sil® (SiO2). Atomization tests with this mixture have been carried out with an air assisted atomizer and water as a reference liquid. The estimated droplet size for the gelled fuel was approx. 100 µm diameter and the water droplets approx. 50 µm.