Aerodynamic Characteristics of Finite Rectangular Wings in Formation Flight with Ground Effect

The concept of formation flight is not new and so is the ground effect as both are done to reduce the drag and improve an aerodynamic efficiency, but the important thing to investigate is what really happens while wings fly in formation when ground effect is present, an important application of which is a flying train. The present work is an attempt towards understanding this complex flow field when the two wings fly in a lead-trail formation within the ground effect using commercial CFD package ANSYS-Workbench (2020 R1). The aerodynamic performance of finite rectangular wings comprising of NACA 2412 airfoil with \({\text{AR}} \approx 6.66\) for both the leading and trailing wings is analysed in the present work. The lift and drag coefficients for a fixed chord-wise separation between them as \(x{/}c = 4\) and for various ground clearances ranging from \(z{/}c = 0.2\) to \(z{/}c = 0.8\) increasing by \(z{/}c = 0.2\) and \(z{/}c = 6.0\) considered to be the wings formation out of ground effect are reported. Angles of attack ranging from \(\alpha = 0^{\circ } \,{\text{to}}\, 21^{\circ }\) are considered so as to explore both pre-stall and post-stall angles. The performance of both wings through \(C_{{\text{L}}}\) , \(C_{{\text{D}}}\) , and aerodynamic efficiency, i.e. \(C_{{\text{L}}} {/}C_{{\text{D}}}\) is investigated.