A formulation based on the evaluation of power conversions within the system allows to overcome the limitations of conventional momentum analyses to study tightly coupled airframe-propulsion configurations such as Boundary Layer Ingestion. The so-called power balance method is applied in a CFD framework to gain insight about the application of this formulation for a wide range of flow conditions and for complex geometries. Not addressed in detail in previous research, it is quantified in this work the evolution of the distribution of energy in the wake of a body subject to turbulence, compressibility effects and angle-of-attack of the incoming flow. For the first time, a three-dimensional geometry representative of a typical aircraft is investigated with the power balance method. The results of a grid convergence study for the application of the power balance method in a CFD framework highlight the importance of generating a mesh with a fine resolution of the flow field globally, paying special attention to the development of the body wake.