Experimental research of acoustical characteristics by power plant of aircraft «An-2« in static conditions

Аuthors

Samokhin V. F.^1*, Moshkov P. A.^2**

1. Central Aerohydrodynamic Institute named after N.E. Zhukovsky (TsAGI), 1, Zhukovsky str., Zhukovsky, Moscow Region, 140180, Russia
2. IRKUT Corporation Regional Aircraft, 26, Leninskaya Sloboda str., Moscow, 115280, Russia

*e-mail: samohin_vf@mail.ru
**e-mail: moshkov89@bk.ru, p_moshkov@ssj.irkut.com

Abstract

Motivations

Work is devoted a community noise problem of light propeller aircrafts. In the paper the basic results of acoustical characteristics experimental research by light propeller aircraft (LPA) of «An-2» in static conditions are presented. Spectral and power characteristics of LPA power plant (PP) acoustical radiation and also directional characteristics are obtained.

The problem due to decrease noise of PP is rather actual for a general aviation LPA, whereas ICAO norms act on maximum community permissible noise levels of such planes [1]. The given work is continuation of author researches [2,3,4] by acoustic characteristics of LPA power plants.

Research object

Measurements of LPA «An-2» acoustic characteristics have been carried out. The plane PP involves an internal combustion engine (ICE) «ASH-62IR» with 4-bladed propeller of variable pitches «AV-2». Measurements of acoustical characteristics were conducted at the various engine power settings determined by a rotational speed of a crankshaft.

Research results

As a result of the executed research it is installed that the basic share of energy (to 75 %) acoustical radiation of thу light propeller aircraft PP at moderate values of a Mach numbers of a rotor velocity (M) It is wet M<0,72 it is concentrated in the field of low frequencies (16-100 Hz) and the important role is played here harmonious and low-frequency broad-band by making radiations of a propeller and the reciprocating engine. At high rotor velocity Mach numbers, (M≈0,8) to ~94 % of acoustical energy of the PP it is radiated by a propeller, in the core, on harmonics of frequency of following of blades. The primary source of broadband acoustical radiation in the field of medium frequencies to 1000 Hz is the vortex sheet behind a propeller, and in the field of high frequencies over 1000 Hz a prospective source is interacting of a vortex sheet behind a propeller with system of an air cooling of the engine. The estimation of the contribution of various spectral components of acoustical radiation in total sound power of the aircraft PP is executed.

It is installed that acoustical efficiency of the aircraft «An-2» PP with 4-bladed propeller on the maximum power condition is equal ≈ 0,055 % that in 2-3 times more low, than at aircrafts with 2-bladed propellers.

Keywords:

a propeller, propeller noise, piston power plant noise, light propeller aircrafts noise

References

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