Aerodynamic Characteristics according to S-Duct Curvature,  and Secondary Flow Reduction

Jihan Song; Kidong Kim

doi:10.6108/KSPE.2026.30.2.009

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2026 Vol.30, Issue 2 Preview Page Next Page

RESEARCH PAPERS

Aerodynamic Characteristics according to S-Duct Curvature, and Secondary Flow Reduction S덕트 곡률에 따른 공력 특성 및 이차 유동 저감 연구

30 April 2026. pp. 9-17

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Abstract

Low observable aircraft have a S-Duct to reduce RCS at the engine face. The S-Duct causes flow separation due to curvature, resulting secondary flow affects the performance of the turbofan engine. In this study, a three-dimensional CFD analysis of UAV S-Duct was performed to investigate internal flow according to the curvature, section geometry changes in S-Duct. In addition, jet injection was applied as a way to reduce secondary flow in the duct. The performance of the duct was evaluated in terms of total pressure recovery and distortion coefficient. The computational results show that the performance is better when the curvature point is located rearward than the baseline and the airflow distortion is significantly reduced with jet injection.

Keywords

S-Duct

Airflow Distortion

Flow Separation

Secondary Flow

Jet Injection

저피탐 항공기들은 엔진 입구면(AIP)에서의 레이더 반사량을 감소시키기 위해 S형 흡입구를 적용한다. S형 흡입구는 곡률에 의한 유동박리가 발생하고 이로 인한 이차 유동은 터보 팬 엔진의 성능에 영향을 미친다. 본 연구에서는 무인기 S형 흡입구를 대상으로 곡률 및 단면 형상에 따른 내부 유동장을 분석하기 위해 삼차원 전산해석(CFD)을 수행하였다. 또한 흡입구 내 이차 유동을 저감하기 위한 방안으로 능동유동제어기법인 Jet injection을 적용하였다. 흡입구 성능은 엔진 입구면에서의 전압력회복률(PR)과 유동왜곡지수(DC60)을 사용하여 도출하였다. 해석결과 곡률점이 후방에 위치할수록 우수한 성능을 보였고, Jet injection을 적용한 경우 유동 왜곡이 상당히 저감됨을 확인하였다.

키워드

S형 흡입구

유동 왜곡

유동 박리

이차 유동

제트 분사

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Information

Publisher :The Korean Society of Propulsion Engineers
Publisher(Ko) :한국추진공학회
Journal Title :Journal of the Korean Society of Propulsion Engineers
Journal Title(Ko) :한국추진공학회지
Volume : 30
No :2
Pages :9-17
Received Date : 2025-10-22
Revised Date : 2026-02-02
Accepted Date : 2026-02-03
DOI :https://doi.org/10.6108/KSPE.2026.30.2.009

Journal of the Korean Society of Propulsion Engineers ISSN:1226-6027(Print) 2288-4548(Online) 한국추진공학회지

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