An Empirical Jet-Surface Interaction Noise Model with Temperature and Nozzle Aspect Ratio Effects

An empirical model for jet-surface interaction (JSI) noise produced by a round jet near a flat plate is described and the resulting model evaluated. The model covers unheated and hot jet conditions (1 ≤ TT,R ≤ 2.7) in the subsonic range (0.5 ≤ Ma ≤ 0.9), surface lengths 0.6 ≤ x TE /Dj ≤ 10, and surface standoff distances (0 ≤ h TE /x TE ≤ 1) using only second-order polynomials to provide predictable behavior. The JSI noise model is combined with an existing jet mixing noise model to produce exhaust noise predictions. Fit quality metrics and comparisons to between the predicted and experimental data indicate that the model is suitable for many system level studies. A first-order correction to the JSI source model that accounts for the effect of nozzle aspect ratio is also explored. This correction is based on changes to the potential core length and frequency scaling associated with rectangular nozzles up to 8:1 aspect ratio. However, more work is needed to refine these findings into a formal model.