Aero-engine components are strongly coupled with each other and traditional design tools are not always able to predict the complex phenomenon caused by component interactions. Whole engine simulations could allow designers to capture this phenomenon, increase the design confidence and reduce design cycles. The aim of this thesis is to reduce the turnover time in the pre-processing of whole engine simulations and conduct CFD simulations of the whole engine gas path. This thesis has developed a set of meshing methods for turbomachinery applications. These methods include multi-block structured meshing, 2D/3D Delaunay triangulation, Q-morph, hybrid meshing and hex meshing. These meshing methods are integrated with the in-house geometry database to reduce the required man-hours in the pre-processing of whole engine simulations. This has reduced the required man-hours from days and weeks to a few hours. The whole engine simulation benefits from the development of the developed preprocessing tool, so that the whole engine gas path can be simulated. A compressible reacting gas model is used throughout the domain to ensure the consistency of gas thermodynamic properties. The turnover time of the preprocessing of a whole engine simulation can be reduced to roughly 8 man hours (one working day), which makes the whole engine simulation a feasible tool in the design process.