Multi-objective Optimization Approach for Low RCS Aerodynamic Design of Aerospace Structures

This paper presents a multidisciplinary, multi-objective optimization approach towards low Radar Cross section (RCS) aerodynamic design of aerospace structures. As a typical example, design and analysis of aircraft intake duct for stealth behavior by integrating computational fluid dynamics (CFD) and computational Electromagnetics (CEM) has been demonstrated. The design constraints (inlet area, throat area, exit area, and diameter) are calculated based on the RAE M2129 diffuser and subsonic flow condition with Mach number 0.8 is considered at the Indian standard atmospheric conditions (ISA_SL + 15). Inlet shaping parameters for intake are modified based on super ellipse equation by retaining the area as constant. Shaping parameter samples have been generated by limiting major axis to maximum length and minor axis to minimum length using MATLAB code. Based on each curvature parameter, three geometries were opted and CAD models are generated from sample space. For these geometries, CFD and CEM analysis has been performed and corresponding pressure recovery and RCS at 10 GHz (X-band) has been estimated. The CFD-CEM performance analysis has been presented for the optimized intake duct geometry. Particle swarm optimization (PSO) in-conjunction with CFD solver and CEM developed indigenous RCS solver has been used for optimization of the designed duct towards stealth characteristics.