Experimentally Testing Commercial and Custom Designed Quadcopter Propeller Static Performance and Noise Generation

摘要

It is important to understand the noise signature of Quadcopter (or Quadrotor) propellers in an effort to reduce noise generation. The near field propeller noise signature of hovering Quadcopters can be significantly reduced by replacing them with custom designed, wide-chord multi-bladed propellers. This paper compares thrust, sound pressure level (SPL) and RPM gathered from a DJ1 stock propeller and several custom designed propellers. At the required thrust of 1.4 Ib_f, the difference in SPL for the two bladed stock propeller and the 2.5 Oval design is to lower the custom propeller rotational speed by 1,300 RPM and the SPL by nearly 16 dB. For multiple blades, from 2-5 using the 2.5 Oval design, the 5 bladed custom propeller requires 3,000 RPM less than the stock propeller to produce the design thrust and is 20 dB quieter. Investigations using a radial microphone traverse downstream of the propeller coupled with smoke visualization show the peak SPL to be around a radial location of about 0.75. All of the results presented are consistent with the theory that the local peak sound pressure level is created by the local shear in the flow field.