Reducing Noise from Single and Twin Supersonic Jets Using Very-Low-Frequency Control

High speed jet noise from Naval tactical aircraft causes operational diculties limiting communication between pilot and carrier deck crew, quickly damages deck crew hearing, and leads to sound-induced structural vibrations and fatigue. Several decades of experimental, theoretical, and computational investigations into the physics and control of jet noise have identified several important sound sources, including wavepackets (Jordan and Colonius, 2013), screech (Ponton and Seiner, 1992), Mach wave radiation (Williams and Maidanik, 1965), and broadband shock associated noise (Norum and Seiner, 1982). Reducing the loudest sources of jet noise, without sacrificing propulsive performance, has relied on intuition (Seiner et al., 2004), parametric survey (Bridges and Brown, 2004), or optimal control techniques (Kim et al., 2014).