Geometry Optimization of a Highly Integrated Flush Intake System Considering the Overall Aircraft

Unmanned Aerial Systems (UAS) are becoming increasingly important in modern aerospace applications, particularly in military environments, where compact integration of engine and intake systems is essential for reducing radar cross-section and optimizing internal space utilization. This paper presents a comprehensive study on the aerodynamic and system-level optimization of a submerged flush intake integrated into the fuselage of the forward-swept wing Unmanned Aerial System (UAS) Sharcs, developed by MBDA Deutschland GmbH. The intake design replaces a conventional subsonic pitot intake with a highly compact, flush-mounted configuration aimed at minimizing drag, improving pressure recovery, and maintaining stable inflow characteristics across a wide range of operating conditions. The proposed intake design deviates from the traditional NACA geometry and is characterized by a diffusive intake system with distinct geometric parameters, which enable the systematic control of vortex positioning and flow entrainment. These vortices help mitigate boundary layer ingestion and reduce the likelihood of flow separation, resulting in improved intake performance. A parametric study, including sensitivity analysis, identified the most influential intake parameters, such as inlet axial position and inflow area. These informed a gradient-free optimization process using an evolutionary algorithm coupled with high-fidelity computational fluid dynamics (CFD) analysis. To evaluate performance, multiple flow quality metrics were applied, including total pressure distortion and swirl coefficients (����60, ����60), pressure recovery, and advanced descriptors such as the area-integrated secondary kinetic energy (��������) and distorted mass flow ratio (��Υ,����). System-level performance was assessed through aerodynamic drag coefficients, which capture the intake's influence on the overall aircraft's aerodynamics. Results demonstrate significant improvements, achieving a pressure recovery of 99.1% at cruise level flight and a freestream Mach number of 0.20. Flow visualization reveals characteristic dual-vortex formation with minimal low-energy fluid regions, confirming the effectiveness of the intake's geometry in maintaining high-quality inflow. This study highlights the advantages of coupling intake and airframe design in the early development stages, enabling a highly integrated solution that balances aerodynamic efficiency, structural compactness, and radar cross-section requirements. The resulting optimized configuration will serve as a reference for further mission-based simulations using the Engine Mission Simulation System (EMSS), currently under development at the Institute of Jet Propulsion (IJP). These findings lay the groundwork for future research into compact, efficient intake systems for next-generation unmanned aerial systems (UAS) platforms.