NUMERICAL STUDY ON THE AERODYNAMIC CHARACTERISTICS OF A DUAL DUCTED-FAN AIRCRAFT DURING HOVERING, CLIMBING AND DESCENDING FLIGHTS

Abstract

Numerical analysis is conducted for a dual-ducted fan aircraft at hover, climb, and descent flight conditions to investigate the aerodynamics and stability characteristics. For practical and rapid analysis, the virtual disk method is employed and, a comparison with the results obtained from the sliding mesh method is performed to evaluate the validity of the method. During hovering flight, an imbalance in pitching moment arises at high collective pitch angles of the ducted-fans, which can deteriorates longitudinal stability. For climb flight condition, pitching moment increases and normal force decreases with climb velocity. Rolling and yawing moment exhibit minor changes at low collective pitch angles but significant changes occur at high pitch angles. For descent flight, thrust increases and pitching moment remains small as descent velocity increases. However, a considerable decrease in pitching moment with descent velocity is identified when the collective pitch angles are low.