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Investigation of Aircraft Plume IR Signature for Various Nozzle Configurations and Atmospheric Conditions

노즐형상 및 대기조건에 따른 항공기의 플룸 IR 신호 연구

  • Kang, Dong-Woo (Department of Aerospace and System Engineering and Research Center for Aircraft Parts Technology, Gyeongsang National University) ;
  • Kim, In-Deok (Department of Aerospace and System Engineering and Research Center for Aircraft Parts Technology, Gyeongsang National University) ;
  • Myong, Rho-Shin (Department of Aerospace and System Engineering and Research Center for Aircraft Parts Technology, Gyeongsang National University) ;
  • Kim, Won-Cheol (Agency for Defense Development)
  • Received : 2013.10.16
  • Accepted : 2013.12.26
  • Published : 2014.01.01

Abstract

Nozzle configurations and atmospheric conditions play a significant role in the infrared signature level of aircraft propulsion system. Various convergent nozzles of an unmanned aircraft under different atmospheric conditions are considered. An analysis of thermal flow field and nozzle surface temperature distribution is conducted using a compressible CFD code. It is shown that the IR level in rear direction is considerably reduced in deformed nozzles, whereas the IR level in adjacent azimuth angles is increased in aspect ratios around 6 due to the plume spreading effect caused by high aspect ratio of nozzles. In addition, an analysis of atmospheric transmissivity for various seasons and observation distance is conducted using the LOWTRAN 7 code and subsequently plume IR signature is calculated by considering atmospheric effects. It is shown that the IR signature is reduced significantly in summer season and near the band of carbon dioxide in case of relatively close distance.

항공기 추진 시스템의 IR 피탐지성은 노즐형상 및 대기조건에 큰 영향을 받게 된다. 그 영향성을 분석하기 위해 대표적 스텔스 무인 항공기와 그 추진 시스템의 형상변형 수축노즐을 고려하였다. 먼저 압축성 CFD 코드를 이용하여 IR 신호 계산에 필요한 열유동장 및 노즐표면 온도 정보를 산출하였다. 플룸 IR 신호를 계산해 본 결과 축방향 신호수준은 상당히 감소하는 반면, 노즐의 좌우 측면에서는 노즐의 가로세로비 증가로 인해 플룸이 좌우로 확장되어 특정 가로세로비에서 상대적으로 증가된 플룸 IR 신호가 발생함을 확인하였다. 다음으로 LOWTRAN 7 코드와 연계하여 계절 및 관측거리 변화에 따른 대기 투과율을 분석하고 그 결과를 바탕으로 대기효과가 고려된 플룸 IR 신호를 계산하였다. 계산결과 계절이 여름일 경우와 비교적 근접의 관측거리에서 이산화탄소 밴드에서 IR 신호가 현저히 감소하는 것을 확인하였다.

Keywords

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