AERODYNAMIC INTERFERENCE CHARACTERISTICS OF BUSEMANN BIPLANE AIRFOIL WITH SLAT AND FLAP IN LOW-SPEED FLOW

Abstract

In this study, aerodynamic interference characteristics of a Busemann biplane incorporating both leading-edge slats and trailing-edge flaps are investigated, utilizing wind tunnel experiments and numerical simulations. The aerodynamic characteristics of the biplane configuration are assessed through a comparative analysis with the performances of its individual upper and lower wings when operating as single configurations. The deflections of the slat and flap are 15° and 30°, respectively. Stall occurred on both the upper and lower wings in the single configuration. The addition of the leading-edge slat enabled the single model to stall at a larger angle of attack, consequently leading to a higher maximum lift coefficient. In the biplane configuration with slat and flap, the lower wing did not experience stall, and its lift coefficient increased with the angle of attack, similar to the case with only trailing-edge flaps. The drag interference ratio was observed to exceed 1.0 at angles of attack below 5° for the biplane with only a trailing-edge flap and below 12° for the configuration including both a slat and a flap. This finding implies that, within these ranges, the biplane generated a higher total drag compared to the sum of the individual drag values of each element in a single-element configuration. The lift interference ratio exhibited a minimum value of 0.72 at 16° for the biplane with both slat and flap.