Experimental Research of Pilotless Vehicle Noise Sources with a Pusher Ducted Propeller
Аuthors1*, 1, 2**
1. Central Aerohydrodynamic Institute named after N.E. Zhukovsky, TsAGI, 1, Zhukovsky str., Zhukovsky, Moscow Region, 140180, Russia
2. Sukhoi Civil Aircraft Company, SCAC, 26, Leninskaya Sloboda str, Moscow, 115280, Russia
In present work the basic results of acoustic tests low-sized pilotless vehicle (PV) are shown. Power plant (PP) of PV is arranged in a tail unit of a flight vehicle. The power plant consists of the two-stroke piston engine of air cooling P-032M and pusher ducted propeller. On the engine the reduction gearbox with the coefficient of reduction ≈ 2,102 is set.
Acoustic tests are conducted for three power conditions of PV power plant: an idle power condition, a cruiser power condition and full power condition. On each power conditions flow velocity in test section of wind tunnel is changed in a range of values from 15 m/sec to 50 m/sec with step 5m/sec.
As a result of an experimental research in a wind tunnel of acoustic radiation from low-sized aircraft power plant with pusher ducted propeller it is established that the total noise level of PP is determined, in the core, by first 10 harmonics of exhaust noise and first 5 harmonics of propeller rotation noise. The contribution of first five harmonics rotation noise to a total intensity of acoustic radiation of PV power plant makes on a mode of idle power condition of ~38 %, on a cruiser power condition of ~23 %, on a full power condition of ~3 %. The acoustic efficiency on full power conditions makes ~1,1 %.
On the basis of the carried out research it is possible to ascertain that in noise of PV power plant including the piston engine with air cooling and pusher ducted propeller, at absence in exhaust tube of the engine of exhaust silencer, a determining source of external noise is the system of an exhaust piston engine.
At the same time, the propeller arrangement in pusher configuration limits capabilities of decrease in exhaust noise of the piston engine as there are difficulties with accommodation of exhaust silencer.
Keywords:low-sized aircraft noise, piston power plant noise
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