Study on Periodical Aerodynamic Noise of a Propeller Fan due to Blade Tip Vortex

Abstract

The objective of this study is to clarify influence of blade tip vortex on aerodynamic noise of a propeller fan operated at the vicinity of maximum efficiency point. The influence of the internal flow on the aerodynamic noise is discussed based on the parameter of axial direction relative position. When the position was 20 mm, the periodical noise at 200 Hz became large. The periodical noise became one of the major factors for increasing the fan noise. The periodical noise was generated by the interaction between the blade tip vortex and the partition of the fan. We clarified that when the wake of the impeller formed the flow regime of the low specific speed type impeller, the periodical aerodynamic noise was generated.