Global characteristics of transverse jets of aviation kerosene–long-chain alcohol blends

Abstract

Long-chain alcohol is a promising alternative for commercial fuels. This study aims at experimentally determining the characteristics of transverse jets using long-chain alcohol in aviation applications. The surface wavelength, breakup regime, upper trajectory of a transverse jet, and liquid column breakup point location are investigated. The column breakup and surface breakup are both observed in experiments, and in the surface breakup regime, there exist bag breakup, multimode breakup, and shear breakup. Shear breakup appears in the conditions with Weg lower than 80. An equation for predicting the upper trajectory of aviation kerosene–long chain alcohol (AKL) blends is proposed. Addition of n-butanol makes the upper trajectory lower, whereas addition of n-pentanol makes the upper trajectory higher. Two equations are proposed for predicting the horizontal and vertical positions of the liquid column breakup point, taking Weg, Oh, and q into account. Blending of n-butanol increases xb and zb, whereas the addition of n-pentanol decreases them. By introducing Kelvin–Helmholtz instability and Rayleigh–Taylor instability into the theoretical analysis, λs is showed to be related with Weg and Oh. Using the results of theoretical analysis, as well as the experimental data, a prediction equation for λs is proposed. The variation of λs caused by fuel modification is studied, the λs is shortened with the addition of long-chain alcohol, and aviation kerosene–n-pentanol blends show shorter surface wavelengths than those of aviation kerosene–n-butanol blends with the same blending ratios. This work provides a better understanding of the characteristics of AKL blends, which will be useful in expanding aviation applications of this fuel.