Lobe Balancing Design Method to Create Frozen Sonic Booms Using Aircraft Components

Abstract

As a sonic boom pressure signal propagates through the atmosphere, the age variable that quantifies nonlinear distortions approaches an asymptotic limit. As this limit is approached, distortion of the pressure signal decreases until it is "frozen." For an aircraft at 51,000 ft and Mach 1.7, the age variable is still 24% away from this limit. Alternatively, a sonic boom may be frozen by balancing lobes in the F function. Software, based on modified linear theory, is used to design an supersonic business jet that uses lifting components to create a lobe-balanced sonic boom. Leading and trailing shock pressure rise, peak overpressure, and perceived level of loudness are evaluated for a several configurations. In one case, the leading shock is reduced from 1.4 to 0.83 psf, and in another, the trailing shock is reduced from 1.2 to 0.87 psf. The software also calculates performance metrics to ensure reasonable longitudinal stability and performance. Off-track signatures demonstrate multishock sonic booms to the sides. Sonic booms are compared with computational fluid dynamics to demonstrate the accuracy of the method.

Ballistic Wave from Projectiles and Vehicles of Simple Geometry

“…For this reason, the sonic boom generated by objects flying at hypersonic velocity at high altitude was the subject of specific studies [40][41][42][43][44][45][46][47][48][49]. The recent orientations concern the minimization of the sonic boom perceived at ground level by suitable aircraft geometry and flight trajectory on the one hand [50][51][52][53][54], the generalization of the computational fluid dynamics (CFD) to replace the analytical models on the other hand [55][56][57][58][59][60]. For a long time limited to the calculation of the aerodynamic field close to the supersonic object, the CFD now tends to increase its spatial range, thanks to the use of adaptive meshes, for instance.…”

Review of Sonic Boom Prediction and Reduction Methods for Next Generation of Supersonic Aircraft

“…These sonic boom types are essentially modified N-waves. Another option to reduce the annoyance of the sonic boom to humans is to generate a multishock signature (Figure 7d) by means of a lobe-balancing method [116,117]. Lobes are created using lift, by trimming lifting surfaces to obtain a frozen, shock balanced F-function, like the one showed in Figure 8, at different flight conditions.…”

Full-Field Sonic Boom Simulation in Real Atmosphere

“…Therefore, the sonic boom reduction is essential for developing the supersonic airplane and the numerous studies of the sonic boom have been conducted. [1][2][3] It is difficult to predict the propagation mechanism of the sonic boom from the near-field around the airplane to the ground because of the multi-scale nature of the phenomena involving both the near-field and the far-field. Hence, the sonic boom prediction is conducted as follows.…”