Experimental investigation of the acoustic emission of an electrically driven propeller in thrust and recuperation mode in a wind tunnel

Abstract

This paper presents the results of an experimental performance study of an electrically driven propeller in thrust and power recuperation mode in a subsonic wind tunnel. Using the reverberation chamber method, acoustic measurements were performed to evaluate them as a reference in relation to the performance data obtained. The three approaches to recuperation were investigated: Fixed pitch propeller at speed reduction (case 1), controllable pitch propeller with negative angle of attack (case 2), and inverted, backward running propeller (case 3). Results show that in-flight recuperation can be optimized in terms of low noise emissions and generating shaft power from the flow efficiently by choosing the respective operating point. For the latter, case 3 shows the greatest potential for a two bladed propeller, while case 2 has the lowest noise emissions and might reach higher values in recuperated power by increasing the propeller blade number.