THE EFFECT OF PYLON TRAILING EDGE BLOWING ON THE PERFORMANCE AND NOISE PRODUCTION OF A PROPELLER

摘要

This paper discusses a study of the effects of pylontrailing edge blowing on pusher propeller performanceand noise emissions. Experimental investigationswere performed in a low speed openjet wind tunnel, using a powered propeller modeland a generic pylon model. A novel pylon blowingsystem was integrated in the aft part of thepylon to provide a uniform outflow. The numericalanalysis was executed using a combinationof a propeller model that is based on an extendedBlade Element Model (BEM) and a set of analyticmethods from the literature, to assess the effectsof pylon installation on the propeller performanceand noise emissions. Measurementsof the velocity distributions in the blown pylonwake showed that application of the blowingsystem reduced the integrated velocity deficitby up to 60% compared to the unblown configuration.Evaluations of the propeller forces andmoments showed that the effects of installationon the time-averaged propeller performance aresmall, with differences of at most 2% for advanceratios below J=1.4. Furthermore, excellentagreement was obtained between the computedand measured performance for the isolated propeller.With respect to the propeller noise emissionsit was observed that installation of the pylonupstream of the propeller strongly increasesthe noise levels. Depending on the propelleroperating point, noise penalties of up to 15dBwere measured. The application of pylon blowingclearly reduced the propeller noise emissionsover the entire advance ratio range, with reductionsof up to 7dB compared to the unblown case.The largest noise reductions were found at thehighest blowing rate, indicating that the most effectiveblowing rate might not have been reachedyet.