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Engine performance
Published in Mohammad H. Sadraey, Aircraft Performance, 2017
Many aircraft engines are built to operate on a number of fuel types. To do so, they must have a special switch on the fuel control to allow it to compensate for differences in specific gravity that is used in fuel metering calculations. There are many other fuels of interest for use in aircraft turbine engines. High-Mach-number aircraft like the SR-71 uses JP-7, a fuel with a very high boiling point. In addition, hydrogen is often considered a fuel because of its very high heating value (a heating value of 116,000 kJ/kg) and its capacity to absorb the thermal loads of high-Mach-number flight. In general, piston engine fuels are about 10% lighter than jet fuels.
Thermal stress stability of hydrocarbon fuels under supercritical environments
Published in Chemical Engineering Communications, 2023
Sundaraiah Konda, Madhavaiah Nalabala, Srikanta Dinda
Substantial research has been performed to recognize fuel cracking behavior under supercritical conditions. The supercritical cracking of various hydrocarbon fuels, such as aviation kerosene (Jiang et al. 2013; Xu and Meng 2015), RP-3 (Gao et al. 2019; Liu et al. 2019), JP-7 (Huang et al. 2004; Wickham et al. 2001), JP-8 (Beaver et al. 2006), JP-10 (Pan et al. 2020; Xing et al. 2008), RP-1 (Andersen and Bruno 2005; Huber et al. 2009), n-decane (Jia et al. 2019; Zhou et al. 2017), and n-dodecane (Jiang et al. 2011; Liu et al. 2008), etc., have been studied by different researchers to examine the suitability of the fuels for supersonic applications. Thermal degradation and coke deposition in the fuel transfer line are the major concerns for using hydrocarbon fuels in regenerative cooling systems (Huang and Spadaccini 2005; Konda et al. 2022; Wang et al. 2020; Xie et al. 2009; Zhu et al. 2014). Hence, analysis of the thermal stability of hydrocarbon fuels is essential to use as a fuel for a supersonic engine. Balster et al. (2006) have studied the surface deposit characteristics of aviation fuels with different compositions of polar species. It is reported that the amount of polar species is directly proportional to the quantity of solid deposits produced. The soot-forming characteristic of high-boiling distillates is relatively more than low-boiling hydrocarbons (Saggese et al. 2019). DeWitt et al. (2011) have studied the supercritical pyrolytic stressing of petroleum-derived fuels (Jet A-1 and JP-8) and Synthetic Paraffinic Kerosene. It is mentioned that the synthetic fuel showed a more than 2 times higher deposition rate compared to the Jet A-1 and JP-8 fuels. Steven et al. (2019) examined the influence of heteroatoms (oxygen, sulfur, nitrogen) on the rate of coke deposits by jet fuels during its autoxidation. The presence of oxygen, sulfur, and nitrogen species enhanced the deposit formation rate, and the influence of sulfur and oxygen species is relatively more than nitrogen species. The sulfur content in jet fuel and the reactor metallurgy can play a critical role in forming the amorphous film of carbon, and for the fluid-phase solid deposits, the influence of these parameters is much weaker (Venkataraman and Eser 2008). In some studies, various additives (Wickham et al. 2008) and initiators (Chakraborty and Kunzru 2012; He et al. 2017; Wang et al. 2008) have been used to minimize the gum/coke deposits during the thermal stressing of hydrocarbon fuels.