INVESTIGATION OF AERODYNAMIC CHARACTERISTICS OF BUSEMANN AIRFOIL INCORPORATING A FLAP AND SLAT IN LOW-SPEED FLOW

Abstract

The Busemann biplane wing employs a unique design, with inter-wing spacing optimized to suppress shock wave formation and minimize drag and noise at supersonic speeds. However, the resulting thin profile leads to reduced lift, impacting takeoff and landing. The use of slats and flaps is a promising approach to enhance takeoff and landing performance. In this research, the low-speed aerodynamic characteristics of Busemann airfoil installed slat and flap are investigated. The slat and flap are configured with hinge points located at 0.3c from the leading and trailing edges. The slat and flap deflection angles are 15° and 30°, respectively. The experiments are performed at a freestream velocity of 15 m/s, corresponding to a Reynolds number of 2.1·105. Results showed that the model incorporating flaps led to increases in both total lift and drag. The maximum lift coefficient increased from 1.6 in the baseline configuration to over 2.15 with the deployed flaps, while the lift curve slope remained relatively unchanged. At positive angles of attack, the lower element's contribution to both total lift and drag diminished compared to the baseline model. The slats effectively increased the lift slope and maximum lift coefficient, fulfilling the lift coefficient requirements for takeoff and landing. Additionally, the slats mitigated flow separation on both the upper and lower element surfaces, resulting in a reduction in drag compared to the configuration with flaps only.