Experimental Flowfield Analyses of Installed Subsonic Jet–Pylon Interaction

Abstract

This paper presents an experimental investigation into the flowfield of single-stream jets blocked by internal and external rigid nozzle structures. The jets studied include axisymmetric round and annular jets and asymmetric blocked pylon jets. The pylon nozzles tested have three different thicknesses, reducing the exit flow area by 5, 10, and 20%. Hot-wire anemometry is used to record the unsteady velocity field both at the nozzle exit and up to 10 jet diameters downstream. Installation effects, created by mounting a wing section close to the jet, and forward-flight effects are also considered. The nominal Mach numbers studied are and 0.6 for the jet flow, and , 0.1, and 0.2 for the flight stream. Results show that the nozzle blockages 1) redirect the jet toward the wing, 2) increase the entrainment rate in locations far downstream of the nozzle exit, 3) produce dominant effects compared to the change of entrainment induced by the presence of the wing, and 4) considerably increase the normalized turbulence intensity generated in in-flight conditions.