The jet engine is a fundamental component of an aircraft system. Its reliable and efficient performance depends significantly on the quality of the airflow reaching the compressor. The flow quality is evaluated by calculating the pressure recovery coefficient and the static pressure distribution along the duct at different circumferential positions. In this context, aiming to achieve greater control over the aerodynamic performance of the inlet duct from the early stages of design, a parameterization of the inlet geometry is investigated and implemented within a reduced-order modeling design tool. To obtain the final inlet configuration, the parameters influencing the coordinates of the duct centerline, responsible for defining the inlet curvature, are represented by a fourth-order polynomial. Additionally, the inlet plane parameters are defined to allow for variations between circular and elliptical shapes, providing greater flexibility in the aerodynamic design process. The quality of the flow at the compressor inlet, an interface plane with the engine (denoted as the aerodynamic interface plane, AIP), is generally quantified by the uniformity of the circumferential flow profile and the level of total pressure loss. The aerodynamic performance of a subsonic inlet was studied using the commercial computational fluid dynamics (CFD) package ANSYS CFX v.19.2, which calculates the flow variables through the duct, thus enabling aerodynamic performance calculations and showing how the geometric parameters of the duct can impact the flow in the duct. The numerical study also serves the purpose of investigating the dependence of the numerical solution on the level of refinement of the computational mesh, with the aim of avoiding unnecessary computational costs and optimizing the simulation process. The numerical results are compared with reliable experimental data to validate the numerical modeling and select the turbulence closure model that presents the best relationship between accuracy and computational cost.