Input-output analysis of heated axisymmetric turbulent jets

Motivated by the recent success of input-output analysis for predicting the aeroacoustics of axisymmetric isothermal high-speed turbulent jets, we apply input-output analysis to axisymmetric heated high-speed turbulent jets. We consider small perturbations about Reynolds-averaged Navier-Stokes (RANS) solutions of perfectly expanded turbulent jets with a range of jet Mach numbers and different levels of applied heating. We show that input-output analysis recovers the far-field acoustics of heated jets and may be used to identify the effects of heating on the sound generation mechanisms associated with turbu­lent jets. We also demonstrate that applied heating causes Mach wave radiation to occur even when the jet Mach number remains subsonic. By projecting high-fidelity large eddy simulation (LES) data onto an orthonormal set of input modes obtained about a time- averaged base flow, we find that sub-optimal modes are active for a M_j = 1.5 supersonic jet with T_j/T_∞ = 1.74.