## 5 LBV of Key Hydrocarbon Components in Aviation Fuel
### LBV of Cycloalkanes in Aviation Fuel  
Representative cycloalkanes in aviation fuels predominantly include cyclopentane, cyclohexane, and their derivatives. [PERSON] et al. employed an externally heated diverging channel approach to measure the LBVs of methylcyclohexane over a wide temperature range (300-610 K) and compared their findings with prior data [96]. By investigating reactivity at 400 K and 610 K, they observed that enhanced formations of C\({}_{2}\)H\({}_{4}\) and C\({}_{2}\)H\({}_{3}\) radicals with increasing temperature led to higher LBVs for methylcyclohexane. [PERSON] et al. reported that mixing ammonia with methylcyclohexane and toluene reduced the LBV of both cycloalkanes due to combined thermal and kinetic effects [97]. [PERSON] et al. measured LBVs of cyclopentane and cyclohexane over broad pressure and tempera  
Figure 8: Illustration of the LBV of iso-alkanes, including butanes (blue), octanes (green), and dodecanes (red), at atmospheric pressure (P = 1 atm) under temperatures of 298 (blue), 353 (green), and 473 (red) K, respectively. The data come from the literature in Table 5.  
ture ranges, finding good agreement with the JetSurF2.0 and Tian models while showing that cyclohexane's LBV exceeds cyclopentane's [98], as indicated by the green triangles in Figure 9. This difference arises because cyclopentane generates larger amounts of methyl and allyl intermediates, which consume H radicals and promote chain termination, while cyclohexane produces more ethyl and 1,3-butadiene species that further generate vinyl radicals, triggering chain branching and faster reactions. [PERSON] et al. measured and compared the LBVs of cyclohexane and multiple cyclohexane derivatives, attributing lower LBVs of mono-substituted cyclohexanes to increased propene and allyl radical formation [99]; [PERSON] et al. likewise arrived at conclusions aligned with [PERSON] et al. and [PERSON] et al., proposing that the symmetric ring of cyclohexane favors the formation of 1,3-butadiene and produces less propene [100]. [PERSON] et al. investigated five six-carbon cycloalkanes (cyclohexane, benzene, cyclohexene, 1,3-cyclohexadiene, and 1,4-cyclohexadiene), noting that the JetSurf model predicts their LBVs satisfactorily, except for that of benzene [101]. [PERSON] et al. summarized data for a variety of hydrocarbons and oxygenated fuels, suggesting that cycloalkanes often exhibit LBVs similar to those of the corresponding alkanes [102], consistent with [PERSON] et al. [67]. Table 6 compiles the experimental conditions, methods, and publication years for LBV tests on various cycloalkanes. The summarized LBV peaks of n-alkanes and cycloalkanes from multiple articles at 353 K and 1 atm are presented in Figure 9, with several insights offered: Firstly, there is no distinct trend in LBV performance between n-alkanes and cycloalkanes of the same carbon number. For C5 and C7 alkanes, n-pentane exhibits a higher LBV than cyclopentane, and n-heptane has a higher LBV than methylcyclopentane. However, for C6 alkanes, n-hexane's LBV is lower than cyclohexane's LBV. Secondly, comparing the LBV performance of cyclohexane and its derivatives in the works of [PERSON] et al. and [PERSON] et al. [100], (represented by red circles and blue squares, respectively), it is evident that the LBV peak of cyclohexane is significantly higher than that of its derivatives. Moreover, the LBV performance differences among methyl, ethyl, propyl, and butyl derivatives of cyclohexane are minimal, which may be attributed to bond energies. Thirdly, while [PERSON] et al. utilized the stagnation flame method for testing, [PERSON] et al. employed the spherical flame method. Although both studies exhibit a similar trend in LBV variations as \"cyclohexane > n-hexane > methylcyclohexane \(\approx\) ethylcyclohexane,\" the LBV values for each alkane measured differ by 1-3 cm/s.