Experimental and Computational Studies of Low-Speed Aerodynamic Performance and Flow Characteristics around a Supersonic Biplane

Abstract

One of the most critical technical issues with regard to supersonic commercial transportation is the sonic boom that occurs during supersonic cruising flight, which causes impulsive noise on the ground. The ''supersonic biplane theory'' has been proposed to reduce the sonic boom. Shock wave interaction and cancellation between the wings of a supersonic biplane can be realized at a specific design Mach number, but does not work at off-design values. Here, the low-speed aerodynamic performance, as off-design performance, of a baseline supersonic biplane was investigated and discussed using experimental and computational fluid dynamics approaches. The thin airfoil stall characteristics of a supersonic biplane were shown to be caused by the stall of both upper and lower wings at an angle of attack of 20. Although there was leading flow separation of the upper wing at lower angles of attack, the stall of the lower wing was suppressed by interference with the upper wing. The lift of the lower wing was almost dominant to produce the lift of the supersonic biplane in the low-speed range. However, the lower wing caused greater drag than the upper wing at higher angles of attack.

Numerical investigation of the effect of stagger on the aerodynamic characteristics of a Busemann biplane

“…As the supersonic aircraft has to undergo subsonic flight at high angles of attack during takeoff and landing, the problems associated with off design low subsonic flights also become important. In this regard, Kuratani et al [14] have experimentally and numerically studied the stall characteristics of supersonic biplane and suggested that the stall is caused by stall in both the upper and lower airfoils at about 20 • . They also found that at low subsonic speeds the lower airfoil dominates the lift produced and also accounts for major proportion of drag at high angles of attack.…”

Numerical analysis of stagger Supersonic biplane at off-design condition with trailing edge flap

“…Yamashita et al have suggested various methods to overcome the issues of choking and hysteresis encountered in Busemann biplane configuration by incorporating leading edge and trailing edge flaps [9]. Kurutani et al studied the Busemann biplane's stall characteristics and found that the stalling angle of attack is 20˚ for both the upper and lower element of the biplane [10]. They also found that the lower element of the biplane dominates the lift produced and produces a high amount of drag at low subsonic speed and a high angle of attack.…”