An Experimental Study on the Aerodynamics and Aeroacoustic Characteristics of Small Propellers

Abstract

A preliminary experimental study was carried out to investigate the aerodynamics and aeroacoustic characteristics of small propellers. A baseline propeller with 120mm radius was designed at first, and four different saw-tooth serrated trailing edges were added to the baseline propeller. The heights (2h) of the saw-tooth serration are 6mm, and the width to height ratio (λ/h) are 0.3, 0.6, 0.9, and 1.2, respectively. The aerodynamic forces, sound pressure level, and detailed flow field structures are achieved via a high sensitive load cell, sound measurement system, and PIV system at hover motion (thrust=3N). The objective of this study was to reduce the noise and maintain the thrust of the small propellers at low Reynold number of 60,000. By adding the saw-tooth serration feature to the baseline propeller, the broadband noise reduction was substantially suppressed at high frequency. Meanwhile, the aerodynamics performance was maintained. The detailed flow measurements of different propellers are also studied to illustrate the mechanism of noise reduction.

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