Numerical analysis of a jet engine test cell

Jet engine test cells provide a controlled testing environment necessary to obtain engine performance measurements that are reliable and repeatable. When constructing a test facility, it is important to consider how its components affect the characteristics of the airflow passing through it. In this regard, the distribution of the flow velocities reaching the engine intake can influence its performance and even compromise its operation. Another important aspect, that is affected by the test cell aerodynamic performance, is its structural integrity, as it must be compatible with the internal wall pressure drop, which varies in severity depending on the cell architecture. In the past, the aerodynamic performance of an engine test cell was studied primarily using fluid dynamic similarity tests conducted on scale models, in order to save on construction time and costs. These advantages are even more pronounced when using Computational Fluid Dynamics (CFD) analysis methods, as they provide increasing modularity of the simulated problem and faster acquisition of the desired information. However, CFD methods alone are not sufficient because they require experimental measurements for the validation of the model itself. This thesis aims to develop a CFD model capable of simulating the internal flow within a jet engine test cell. Furthermore, it intends to validate this model by comparing the numerical results obtained with experimental measurements derived from a scale test campaign. Lastly, this work aims to develop a tool useful for making design decisions regarding the modernization of existing engine test facilities or the construction of new ones. For these reasons, this work performed a CFD investigation to provide a simulation of the internal flow within the scaled model of the engine test cell used for the aforementioned experimental campaign. In addition to a three-dimensional simulation of the entire cell, a sensitivity study on the geometry of the baffles package was also carried out, proposed in both two-dimensional and three-dimensional versions. Furthermore, a mesh independence check was conducted to exclude any unwanted dependencies. Subsequently, a dedicated study was implemented to evaluate the effect that different turbulence models (k-epsilon, k-omega, k-omega SST) have on the final numerical results. Finally, the effect of various operating conditions was investigated to understand the model's range of applicability and its capabilities. This study suggests that a full three-dimensional CFD analysis representing turbulence with a k-epsilon model can provide a wall pressure drop estimate that differs by less than 5% from experimental measurements. Additionally, this model allows for a comparative analysis of different cell architectures, determining which one is associated with better aerodynamic performance in terms of internal pressure drop and velocity distribution at the engine inlet.