Engine-over-the-wing noise research

Abstract

Acoustic measurements for large model engineover-the-wing (EOW) research configurations having both conventional and powered lift applications were taken for flap positions typical of takeoff and approach and at locations simulating flyover and sideline. The results indicate that the noise ,is shielded by the wing and redirected above it, making the EOW concept a prime contender for quiet aircraft. The large-scale noise data are in agreement with earlier small-model results. Below the wing, the EOW configuration is about 10 PNdB quieter than the engine-under-the-wing externally-blownflap for powered lift, and up to 10 dB quieter than the nozzle alone at high frequencies for conventional lift applications.

Geometry considerations for jet noise shielding with CTOL engine-over-the-wing concept

“…Jet-wing interaction noise source I peaked near 160 hertz and resulted in an apparent local increase in SPL level of less than 3 dB with jet velocity of 670 ft/sec (ref. 4).…”

“…1 to 3) and to a more limited extent with a largescale configuration (ref. 4). A typical example of jet noise shielding by a wing is shown in figure 3, wherein the sound pressure level is plotted as a function of frequency for the cases of nozzle alone and nozzle with wing.…”

Externally Blown Flap Noise Research

“…33) with similar data from the large UTW EBF model. Both models (#17 and #3 of table I) used the same seven-foot chord wing section and 13-in.…”

“…-These data have been correlated in terms of nozzle exit flow parameters and generally correlate quite well with the sixth power of the nozzle exhaust velocity, V (ref. 33). Therefore equation (2) can be used in the form …”

“…-Typical flap noise radiation patterns at 50 foot radius for the large OTW model are shown in figure 19 (taken from ref. 33). The OASPL is given as a function of the angle from the inlet in the flyover plane ( fig.…”