The effect of the nozzle inflow conditions is investigated by using large-eddy simulations of supersonic jet noise emanating from an F404 nozzle at model scale. We have previously investigated this effect at an intermediate jet temperature, but the current work extends to a higher jet temperature which is comparable to those observed at afterburning power levels. As have been observed at the relatively lower jet temperature, the nozzle boundary-layer thickness affects the nozzle-exit condition and the downstream shock-cell structure, but the effect on the far-field noise is negligible. In addition, the temperature dependence of the specific heat ratio can also modify the nozzle-exit condition and affect the downstream shock-cell size. Additional nozzle inflow turbulences are simulated by using a bypass cooling flow upstream of the exhaust nozzle. It is found that the effect of the nozzle turbulences on the shock-cell structure and the jet core length increases with the jet temperature. If there are no instability waves observed inside the nozzle, however, the far-field noise intensity is not sensitive to changes in the nozzle turbulences, at least for those tested in this paper. On the other hand, if instability waves are present, the jet plume and shock cells can be greatly perturbed, and high-intensity harmonic tones can be observed in the far field. Furthermore, increasing the jet temperature can amplify or even generate instability waves that may not be visible at a lower jet temperature.
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