On Assessing the Influence of Fuel Flammability on the Acceleration and Transient Performance of a Fighter Engine

• Main Authors: Chang gu-bao, 張顧寶
• Other Authors: Shiah S.M.
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/32524959356184316940

碩士 === 國防大學中正理工學院 === 兵器系統工程研究所 === 93 === Due to its heavy influence on the critical flight performance and aviation safety of a fighter airplane, the design of a modern engine has become a state-of-art full of compromises and challenges. For example, it has to avoid all possible engine stall or surge, burner flameout and turbine overheat, while in fully supporting the fighter’s demands of maneuverability, agility, stability and power, even may contradict with each other. Meanwhile, since the power comes from the combustion of fuel, so how to connect the fuel property to the engine performance, with well-derived relation formulas, is of practical interest to the engine design work. These properties include the specific gravity, heating value, freezing point, vapor pressure, flashing point, and flammability, etc. However, from the viewpoint of control logic design of fuel flow and the usual request of an optimal fuel/air ratio setting, a theoretical study of the flammability effect on the engine performance seems to be more relevant, thus forming the present subject. In contents, the research is conducted in three stages: (1) a literature study of the novel approach by Otto and Taylor III [12] as an entry point for further analysis of the engine transient performance, such as acceleration, torque, and response time constant, when subject to changes of fuel flow under different settings of the fuel/air ratio, (2) a typical case study of the J85 turbojet with the fuel of JP-4, (3) a trend analysis of the results from the case study. Through these topic studies, major achievements are as follows: (i) a theoretical architecture has been set up for assessing the effect of flammability on the transient performance and dynamic response of a turbojet, (ii) a PC-based computer program, named CSJP-10, has been developed according to the architecture and with user-friendly windows as the data I/O interface, (iii) a series of trend predictions for the J85 transient performance within its bound of operating space and fuel flammability. On the basis of this thesis, the study of a modern turbofan is greatly encouraged as a possible extension.