Effect of Low-Boom Waveform on Focus Boom Using Lossy Nonlinear Tricomi Analysis

Focus boom occurs when a flight vehicle accelerates or maneuvers at supersonic speed. Its overpressure is typically more than three times greater than that of a cruise boom. As a result, future supersonic transports are likely to face restrictions on their flight conditions. To investigate ways to alleviate this problem, this paper presents the effects of the focusing of several sonic boom signatures. So-called low-boom waveforms have promising characteristics, not only in cruise but also in transition flight phases including acceleration from Mach 1. Computations of the focused waveform for several accelerations at a constant altitude reveal that the low-boom ramp and flattop waveforms show strong reductions of the peak overpressure and perceived level measured on the ground track of the aircraft. Acceleration strongly impacts on the size of the noise exposure footprint of the focus boom, whereas the peak overpressure and the metric are not sensitive. Also shown is the importance of applying the low-boom concept to not only the front but also the rear section of the boom signature.