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Quasi-Steady-State Scheme and Application on Prewhirl Flow and Heat Transfer in Aeroengine
Hong Xiao,Zhe-Zhu Xu,류성기 한국정밀공학회 2015 International Journal of Precision Engineering and Vol.16 No.2
For solving three-dimensional complex unsteady flow to predict aerodynamic characteristics of turbine disc cavity in aeroengine, aquasi-steady-state scheme is proposed. To validate and get reliable turbulence model, three-dimensional numerical studies, of turbinedisc cavity prewhirl flow and heat transfer, are conducted. For comparison, unsteady state computational fluid dynamics simulationsof prewhirl flow are also performed. Five turbulence models, including standard k-å model, RNG k-å model, Realizable k-å model,SST k-ù model and RSM model, are applied both quasi-steady-state scheme and unsteady CFD. Then, reliable quasi-steady-statescheme is obtained and the feasibility, instead of unsteady-state CFD simulation for reducing time resource, is verified. Furthermore,investigations of prewhirl flow and heat transfer in turbine disc cavity of aeroengine are conducted by the proposed quasi-steady-statescheme. It was found that the rotation Reynolds number should be increased to strengthen the blade cooling and weaken the heattransfer in turbine disc cavity. All the results are applied in the design of aeroengine. Also, it proves that quasi-steady-state schemeis effective in the prediction of aerodynamic characteristics in aeroengine.
Analysis of skid damage to cylindrical roller bearing of mainshaft of aeroengine
Xiangyu Xie,Jin Xu,Jun Luo 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.8
Skid damage to mainshaft bearings on aeroengines severely reduces aircraft reliability. In this study, a batch of cylindrical roller bearings extracted from mainshaft of inservice aeroengines with, skid damage after a certain service period, were collected, and damage features of the bearings were characterized and compared with those of the undamaged bearings and the new ones. Microscopic feature evaluation, elemental analysis as well as the composition distribution of the bearings were conducted using scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, transmission electron microscopy and surface profilometry. Analysis results reveal that skidding itself is a very complex process initiated by the action of different mechanisms, and manifest in different wear types. The damage mechanism of skid damaged bearings was the joint consequence of abrasive wear, oxidation wear and delamination wear. All the aforementioned damage and wear led to severe aircraft failures.
김재환(Jae-Hwan Kim),이경재(Kyungjae Lee),문경찬(Gyeong Chan Moon),박수열(Sooyoul Park),김명효(Myeonghyo Kim) 한국추진공학회 2018 한국추진공학회 학술대회논문집 Vol.2018 No.5
소형민수헬기(LCH, Light Civil Helicopter) 개발사업을 통해 개발된 엔진은 민수 인증(형식 증명) 획득 후 소형무장헬기(LAH, Light Armed Helicopter)용으로 활용될 예정이다. 따라서 형식 증명된 민수 엔진의 군용 항공기 적용 적합성 입증을 위해 추가적인 요구도와 입증이 필요한 지에 대한 분석은 매우 중요하다. 본 연구에서는 이를 위한 기초자료 제공을 위해 군용 엔진 개발기준인 미 국방성의 합동운용규격지침서(JSSG-2007)와 민수엔진 형식 증명 기준인 EASA의 CS-E를 비교 분석하여 민/군 규격의 차이점(특히 엔진 운용 환경 조건)을 분석하고 향후 추가적 입증 여부 분석을 위한 기초자료를 제시하였다. An comparative analysis between military and civil airworthiness certification specification for aeroengine has been performed to provide basic information to specify additional substantiation activities, if any, to show compliance of a type certified civil engine to airworthiness criteria of a military rotorcraft. The military and civil airworthiness certification specification of aeroengine is JSSG-2007 by DOD and CS-E by EASA, respectively. Special attention has been paid to environmental conditions such as atmospheric conditions, ingestion capabilities and E3.
Lu Zehua,Liu Chang,Liao Changjun,Zhu Jiazan,Liu Huaiju,CHENYIMING 한국CDE학회 2024 Journal of computational design and engineering Vol.11 No.1
The advancement in materials and lubrication has significantly improved the load-carrying capability of polymer gears, making them ideal for replacing metallic gears in power transmission. However, this conversion is not as simple as substituting steel with polymer; it requires a thorough redesign of the structural parameters specific to polymer gears. To enable the metallic-to-polymer conversion of gear in power transmission, a model for optimizing polymer gear systems was developed. An investigation of the accessory transmission system of a low-thrust turbofan aeroengine was conducted. A comprehensive performance index for the accessory transmission was developed using combined weighting coefficients to achieve the optimization goals including total mass, transmission efficiency, maximum transmission error, and so on. The polymer gear system developed using the proposed optimization model demonstrated a 70.4% reduction in total mass compared with the metallic gear system, as well as a transmission error decrease of over 29% when compared with polymer gear systems with standard tooth profiles. The contribution analysis results demonstrated that optimizing the tooth width, pressure angle, and addendum height of polymer gears can significantly enhance the load-carrying capacity of the polymer gear system while maximizing tooth profile flexibility.
Probabilistic vibration and lifetime analysis of regenerated turbomachinery blades
Berger, Ricarda,Rogge, Timo,Jansen, Eelco,Rolfes, Raimund Techno-Press 2016 Advances in aircraft and spacecraft science Vol.3 No.4
Variances in turbomachinery blades caused by manufacturing, operation or regeneration can result in modified structural behavior. In this work, the scatter of geometrical and material properties of a turbine blade and its influence on structure performance is discussed. In particular, the vibration characteristics and the lifetime of a turbine blade are evaluated. Geometrical variances of the surface of the blades are described using the principal component analysis. The scatter in material properties is considered by 16 varying material parameters. Maximum vibration amplitudes and the number of load cycles the turbine blade can withstand are analyzed by finite element simulations incorporating probabilistic principles. The probabilistic simulations demonstrate that both geometrical and material variances have a significant influence on the scatter of vibration amplitude and lifetime. Dependencies are quantified and correlations between varied input parameters and the structural performance of the blade are detected.