A large eddy simulation approach and different breakup models are used to analyze fuel injection and atomization processes in a constant volume combustion bomb. The study is focused on the influences of the subgrid turbulent kinetic energy, especially the source term induced by the fuel spray, on the droplet movement and spray characteristics. Furthermore, the influence of different subgrid scale (SGS) models, including the constant coefficient and dynamic Smagorinsky models, WALE model and the K-equation turbulent energy transport model, on fuel sprays and the turbulent dispersion of droplets are examined. Factors affecting the fuel spray are discussed based on numerical computations for various operating conditions and are compared with experimental data. Computational results show that the KH-RT breakup model is superior to the MTAB model, and both the subgrid turbulent energy source term induced by the spray and the turbulent dispersion of the droplets have important effects on the fuel spray, resulting in decreased spray penetration. The effect of the turbulent dispersion is found to be more prominent.