Knock combustion investigation on a two-stroke spark ignition UAV engine burning RP-3 kerosene fuel
Aircraft Engineering and Aerospace Technology
ISSN: 0002-2667
Article publication date: 16 July 2019
Issue publication date: 21 October 2019
Abstract
Purpose
The purpose of this paper is to investigate the knock combustion characteristics, including the combustion pressure, heat release rate (HRR) and knock intensity of aviation kerosene fuel, that is, Rocket Propellant 3 (RP-3), on a port-injected two-stoke spark ignition (SI) engine.
Design/methodology/approach
Experimental investigation using a bench test and the statistical analysis of data to reflect the knock combustion characteristics of the two-stroke SI unmanned aerial vehicle (UAV) engine on RP-3 kerosene fuel.
Findings
Under the full load condition of 4,000 rpm, at the ignition timing of 25 degree of crank angle (°CA) before top dead centre (BTDC), the knock combustion is sensitive to the thinner mixture; therefore, the knock begins to occur when the excess air ratio is larger than 1.0. When the excess air ratio is set as 1.2, the knock obviously appears with the highest knock intensity. At the excess air ratio of 1.2, better engine performance is obtained at the ignition timing range of 20-30 °CA BTDC. However, the ignition timing at 30° CA BTDC significantly increases the peak combustion pressure and knock intensity with the advancing heat release process.
Practical implications
Gasoline has a low flash point, a high-saturated vapour pressure and relatively high volatility, and it is a potential hazard near a naked flame at room temperature, which can create significant security risks for its storage, transport and use. The authors adopt a low-volatility single RP-3 kerosene fuel for all vehicles and equipment to minimise the number of different devices using various fuels and improve the military application safety.
Originality/value
Most two-stroke SI UAV engines for military applications burn gasoline. A kerosene-based fuel for stable engine operation can be achieved because the knock combustion can be effectively suppressed through the combined adjustment of the fuel amount and spark timing.
Keywords
Acknowledgements
This study was funded by the Introduce Talent Funding for Scientific Research at Nanjing Tech University (Grant Number 3827401744), National Natural Science Foundation of China (51865031), and the Science and Technology Research Project of Jiangxi Provincial Education Department (Grant Number GJJ170789). The research project was also supported by the Jiangsu Province Key Laboratory of Aerospace Power System (Grant Number CEPE2018003).
Citation
Liu, R., Sheng, J., Ma, J., Yang, G., Dong, X. and Liang, Y. (2019), "Knock combustion investigation on a two-stroke spark ignition UAV engine burning RP-3 kerosene fuel", Aircraft Engineering and Aerospace Technology, Vol. 91 No. 10, pp. 1278-1284. https://doi.org/10.1108/AEAT-08-2018-0232
Publisher
:Emerald Publishing Limited
Copyright © 2019, Emerald Publishing Limited