Study of the Propellers Noise of Light Aircraft under Static Conditions

The paper presents the results of static tests of propellers of light aircraft AN-2, YAK-18T, MAl-223M, MAI-890, MAI-890U and F30. The characteristics of the directional noise of propellers for the first three tones when operating at elevated modes are generalized. The energy dependences of the sound power of the individual components of the propeller noise on the rotational speed are obtained. It is established that the sound power of the tonal components in the noise spectrum of the propellers decreases on average for all the investigated modes of operation of propellers with a frequency of −3. Based on this, the semiempirical model of propeller noise has been corrected. It is shown that the dominant source of propeller noise under static condition is the component from the unsteady load on the blades due to the inhomogeneity and turbulence of the incoming flow.