Analysis of focus boom test cases using the lossy nonlinear Tricomi equation

Abstract

Focused sonic booms will result from an aircraft accelerating from subsonic to supersonic airspeeds. Sonic boom focusing leads to amplification and phase change of the sonic boom signature and can be modeled by a form of the nonlinear Tricomi equation. This presentation will use the lossy nonlinear Tricomi equation (LNTE) to examine sonic boom focusing for two sample cases. The first case depicts an aircraft with constant rectilinear acceleration at a constant altitude. The second case is slightly more complicated with an aircraft maneuvering at a small climb angle, while accelerating and simultaneously pitching downward. Time-pressure histories at various locations in the illuminated zone above the caustic and in the evanescent zone below the caustic will be provided for each test case.