An active control method for reducing sonic boom of supersonic aircraft

Abstract

Sonic boom reduction has been an urgent need to develop the future supersonic transport, because of the heavy damages of the noise pollution. This paper provides an active control method for the supersonic aircraft to reduce the sonic boom, wherein a suction slot near the leading edge and an injection slot near the trailing edge on the airfoil suction surface are opened, and the mass flow sucked in near the leading edge is equal to the mass flow injected near the trailing edge. The diamond and 566 airfoils are adopted as the baseline airfoil to verify the capability of the active control method, and the effects of the suction and injection location, the mass flow rate and the attack angle on the ground boom signature, the maximum overpressure, the drag coefficients and the ratio of lift to drag are studied in detail. The results show that the proposed active control method can significantly reduce the sonic boom, and the reduction of the sonic boom intensity is more sensitive to the injection near the trailing edge than the suction near the leading edge. Applying this active control method to the diamond (NACA0008) airfoil, when the mass flow rate is 6.5 kg/s(7.5 kg/s), the value of maximum positive overpressure is decreased by 12.87%(12.85%), the value of maximum negative overpressure is decreased by 33.83%(56.77%) and the drag coefficient is decreased by 9.50%(10.96%). It can be seen that the method proposed in this paper has great benefits in the reduction of sonic boom and provides a useful reference for designing a new generation of lower sonic boom supersonic aircraft.

Effect of ultrasonic impact treatment on corrosion fatigue performance of friction stir welded 2024-T4 aluminum alloy

“…This occurrence is conducive to the development of intergranular corrosion. Simultaneously, the volume of intergranular corrosion products is larger than the original aluminium alloy consumed by corrosion and dissolution, and the corrosion products generate external thrust on the elongated grains during rolling in the form of wedging [26]. Owing to the wedging and extrapolation of corrosion products, corrosion continues and produces stress concentration at the tip of the interface, allowing spalling corrosion and stress corrosion cracking to develop [27].…”