Grid fins are advanced control surfaces designed for enhanced maneuverability at high angles of attack and across a wide Mach number range. They feature an outer frame supporting a lattice of small chord planar surfaces aligned transverse to the airflow. This study conducts viscous numerical simulations at a subsonic Mach number (0.3 ≤Ma ≤0.5) and high angles of attack to examine and compare the effects of aspect ratio (5 ≤ AR ≤ 10) on the aerodynamic characteristics and flow-physics related to four distinct grid patterns in an isolated grid fin configuration. Moreover, the study offers a detailed comparison of how aerodynamic coefficients increase with aspect ratio across different grid fin patterns. The numerical results aligned well with the reference experimental study data, with solver validation indicating a deviation within 9.8%. Study confirms the presence of improved aerodynamic performance for increasing aspect ratio in all grid patterns in subsonic conditions. However, the extent of improvement is grid pattern -dependent, with hexagonal and square fins standing out as the most aerodynamically efficient and robust solution for subsonic control surface design, offering a compelling blend of increased lift generation, minimizing drag, and aerodynamic stability suitable for a variety of aerospace applications like Unmanned Aerial Vehicles, and missile applications.
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