Journal of the Korea Institute of Military Science and Technology (한국군사과학기술학회지)

The Korea Institute of Military Science and Technology (한국군사과학기술학회)
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Discrete Noise Prediction of Small-Scale Propeller for a Tactical Unmanned Aerial Vehicle

소형 전술급 무인항공기 프로펠러의 이산소음 수치해석

  • Ryu, Ki-Wahn (Department of Aerospace Engineering, Chonbuk National University)
  • 유기완 (전북대학교 공과대학 항공우주공학과)
  • Received : 2018.08.23
  • Accepted : 2018.11.16
  • Published : 2018.12.05
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Abstract

Discrete noise signals from a small scale tactical unmanned aerial vehicle(UAV) propeller were predicted numerically using time domain approach. Two-bladed 29 inch propeller in diameter and 150 kgf in gross weight were used for main parameters of the UAV based on the actual size of the similar scale vehicle. Panel method and Farassat formula A1 were adopted for aerodynamic and aeroacoustic analysis respectively. Time domain signals of both thickness and loading noises were transformed into frequency domain to analyze the discrete noise characteristics. Directivity pattern in a plane perpendicular to the rotating disc plane and attenuation of noise intensity according to double distance were also presented.

Keywords

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Fig. 1. Small size tactical UAV for reconnaissance

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Fig. 2. Wankel rotary engine(38 hp @ 7800 rpm)

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Fig. 3. Blade shape along the radial position including designed propeller shape

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Fig. 4. Performance curves for the designed propeller

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Fig. 5. Comparison of running thrust along the blade span for 1/7 scale Uh-1H rotor blade[10]

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Fig. 6. Comparison of noise signal for UH-1H rotor

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Fig. 7. Wake geometry for Case 3

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Fig. 8. Timewise noise signals at disc plane(1.5 times propeller diameter apart from disc center)

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Fig. 9. Noise spectrum for the timewise noise signals

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Fig. 10. Chart of sound attenuation in distance

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Fig. 11. Typical cases of sound pressure level[15]

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Fig. 12. Directivity patterns(solid line: loading noise, dashed line: thickness noise, dotted line: propeller disc plane)

Table 1. Specifications for two tactical UAVs

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Table 2. Design parameters for UAV propeller

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Table 3. Operating conditions for UAV propeller

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Table 4. Overall sound pressure level [dBA]

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