Empirical metod of predicting aviation piston engine noise

The article suggests an empirical method of predicting noise of aircraft gasoline engines with carburetion used in light and unmanned aviation. The method is based on classical approaches of aeroacoustics to the calculation of environmental noise from different sources. The spectrum of acoustic power is proposed to be obtained on the basis of an empirical model similar to the known M. Khekl҆ model for the calculation of noise of internal combustion piston engines of ground application, but at the same time taking into account the key features of aircraft engines. The calculated and experimental data on integral characteristics of the acoustic field of aviation piston engines are shown to be in good agreement. Experimental data on the noise of aviation piston engines like Ash-62IR, M-14P, ROTAX-912ULS with and without cowling, ROTAX-582UL were obtained during acoustic tests of light propeller aircraft  An-2, Yak-18T, MAI-223M, MAI- 890U and MAI-890, respectively, under static conditions at a local aerodrome. At the same time the acoustic field of the piston engine was supposed to be axially symmetrical relative to the crankshaft axis and the noise of the engine was determined by the total radiation at the harmonics of flash recurrence rate in the cylinders.