Breakup Regimes Research Articles

Theoretical deformation modeling and drop size prediction in the multimode breakup regime

A theoretical model has been proposed to incorporate internal flow mechanics to better predict the deformation and the resulting breakup of a liquid drop in a continuous uniform air jet in the multimode breakup regime. A Weber-number-dependent breakup criterion predicts the deformation of the drop at the time of the breakup, which occurs at the time the internal pressure at the drop equator exceeds internal pressure at the pole. This breakup criterion is used to determine an improved coefficient used in the Taylor Analogy Breakup (TAB) model. The TAB model is also extended to include the effects of turbulence within the drop. Hill vortices form within the drop as a result of viscous forces and flow around the drop. It is proposed that these vortices contribute to the deformation that eventually leads to the outer ring and smaller drop within the ring that is classic to multimode breakup. Instability analysis is used to model the breakup of the outer ring and predict the resultant droplet sizes. The model-predicted breakup times and ring breakup droplet diameter are compared with experimental results collected using digital in-line holography.

Secondary breakup of shear thickening suspension drop

To explore the effect of shear thickening behavior on the secondary deformation and breakup of cornstarch–water suspension droplets, an experimental investigation is conducted by using a high-speed camera. The experimental results demonstrate suspension droplets that exhibit discontinuous shear thickening (DST) exhibit a hardened deformation mode when they fall into the airflow field. When the droplets are in a hardened deformation mode, the windward side of the droplet deforms into a sheet, while the leeward side remains hemispherical until the droplet leaves the airflow field. The dimensionless number N is established to describe the relative magnitude of the increment of the viscous force and aerodynamic force during the secondary breakup process. Based on the suggested dimensionless number N and the Weber number We, the secondary deformation and breakup regime map of Newtonian fluids and DST suspensions is also proposed.

High-speed imaging database of water jet disintegration Part II: Temporal analysis of the primary breakup

This paper is Part II of a series of articles focusing on the disintegration of a cylindrical (Ø=0.60 mm diameter) water jet in a quiescent atmosphere, from Rayleigh to early atomization breakup regimes. Liquid fluorescence high-speed imaging is used here, instead of shadowgraphy, providing a more faithful representation of liquid jet breakup dynamics as described in Part I (Roth et al., 2021). Using these data, the aim of this article is to perform a temporal analysis of the primary breakup process and to investigate the variation of breakup length in the time-domain, under each breakup regime. The results indicate that the liquid jet velocity at the onset of primary breakup oscillates within 6% of the liquid injection velocity for all considered operating conditions. The analysis of the dynamic instability is also performed, showing the growth rate of the first three high-energy-containing modes. The results confirm that there is no single disturbance at a specific frequency whose growth rate leads to liquid jet disintegration in the second wind-induced breakup regime and the early atomization regime. However, it is found that the dimensionless mean breakup length monotonically varies with the product of the dimensionless amplitude by the dimensionless temporal growth rate. The values provided for the dominant frequencies and growth rate of disturbances can be useful for modelers simulating the breakup of liquid jets in a quiescent atmosphere. Finally, the temporally resolved image series analyzed in this article can be further investigated and compared with simulation results, by downloading the processed image data on the website:https://spray-imaging.com/water-jet.htmlor alternatively on Open Science Framework at: https://doi.org/10.17605/OSF.IO/CG3DF

Influences of wall superheat and channel width ratio on bubble behaviors and heat transfer within a heated microchannel T-junction

Despite many studies conducted to reveal the bubble behaviors and associated heat transfer within straight microchannels, those within heated microchannel T-junctions are relatively few. In this paper, the ANSYS Fluent 17.0 enhanced by user-defined functions (UDFs) is utilized to perform 2D simulations on an evaporating bubble passing through the heated T-junction. The influences of wall superheat (ΔT) and channel width ratio (W*) are investigated. Four typical breakup regimes (Non-breakup, “Tunnel” breakup type one, “Tunnel” breakup type two, and obstructed breakup) are observed and the corresponding phase diagram is drawn. The heat transfer characteristics for different heated walls are quantitatively assessed. The bubble behaviors have great impact on the heat transfer characteristics of T-junction. The oscillation of relatively small bubble produces obvious local heat transfer enhancement. The occurrence of tunnel is found to weaken the heat transfer enhancement. It should be noted that the serpentine flow structure occurring at larger W* also significantly influences the heat transfer of branching channel. Generally, the overall heat transfer performance tends to increase with increasing ΔT or decreasing W*. This study contributes to a better understanding of bubble behaviors within microchannel T-junctions.

Dynamic mode decomposition of elliptical liquid jets in crossflow

The dynamics of round and elliptical liquid jets in subsonic crossflow was studied using high-speed imaging technique. The experiments were performed at constant gaseous Weber number and liquid–gas momentum flux ratios of 6.45 and 17.87, respectively, with orifices of different aspect ratios (AR) having an equivalent diameter of 0.43 mm. All of the cases were carried out inside an open-loop subsonic wind tunnel with a test section of 100 mm × 100 mm × 750 mm. For each case, dynamic modes were generated directly from the snapshots using a variant of the Arnoldi method known as the dynamic mode decomposition (DMD). The DMD results indicate that elliptical liquid jets have more small-scaled patterns with higher frequencies compared with the round liquid jets. As the first attempt to investigate the dynamics of elliptical liquid jets in crossflow, this study captures the dominant spatiotemporal structures. We also found that the orifice AR can significantly alter the jet wavelengths. The data from this study contribute to understanding the behavior of elliptical liquid jets exposed to gas crossflow in an enhanced capillary breakup regime.

On the Volume of Fluid Simulation Details and Droplet Size Distribution inside Rotating Packed Beds

In this research, the volume of fluid (VOF) method is used to study the hydrodynamics of rotating packed beds (RPBs). The model is validated, and grid independence analyses are performed for cases with different operating conditions. The droplet size distribution is investigated to characterize the hydrodynamics of RPBs. Droplet size distributions are compared in two-dimensional and three-dimensional simulations, and it is demonstrated that two-dimensional simulations can provide an accurate prediction while significantly reducing the significant computational cost. Radial distributions of droplet diameter in the packing region are studied, and different trends are observed at different rotational speeds (fluctuating at ω = 250 rpm, increasing–constant at ω = 500 rpm, and decreasing at higher rotational speeds). These trends are explained using the breakup and coalescence of droplets during droplet–packing and droplet–droplet collisions. Breakup, coalescence, and deposition regimes of droplets depend on the Weber, Ohnesorge, and impact parameters. We observed that with increasing rotational speed, the average droplet diameter and its standard deviation decreased, while changing the liquid flow rate did not significantly affect the average droplet diameter. It is also observed that there is a critical rotational speed (depending on the bed configuration), beyond which the average droplet size does not decrease with increasing rotational speed.

Electrohydrodynamic disintegration of dielectric fluid blended with ethanol

Engineered fluid HFE-7100 is an outstanding detergent and coolant with excellent thermal and chemical stability. Electrohydrodynamic jet disintegration and subsequent droplet formation of HFE-7100 dielectric liquid mixed with ethanol were experimentally investigated in this study. Contact-type charging was employed with the capillary nozzle directly connected to a negative high-voltage power supply, while the counter electrode was grounded. High-speed photography was utilized to capture the liquid breakup and droplet formation behaviors. The results showed that an ethanol content of 8% by volume visibly improved the charging performance of HFE-7100 due to the increase in the liquid electrical conductivity. In addition, with the increase in the applied voltage, the jet breakup was found to transform from the dripping/jetting mode to the ramified mode, which is characterized by a steady liquid sheet with fine droplets forming at the edge. Two distinct ramified breakup configurations, called the pudgy-ramified and lanky-ramified modes, are proposed, and their detailed structural parameters and droplet size distributions are discussed. The diameters of the droplets produced under the permanent ramified configuration could be as small as a few micrometers. Finally, a jet breakup regime map based on the Reynolds number Re and electric bond number BoE was established. Overall, the electrospray technique has shown promise for spray cooling enhancement, and the main results of this paper may be useful for the development of electrospray cooling with a dielectric coolant.

Development of an aqueous surrogate for the spray performance evaluation of viscous bioliquids

Motivated by the importance of spray evaluation of viscous bioliquids prior to their deployments in combustion devices for heat and power generation, an aqueous surrogate was developed using water, glycerol, and a surfactant for nozzle design and optimization purposes. It provides a safe, clean, and transparent alternative for the spray characterization of bioliquids in a laboratory environment, compatible with different diagnostic methods. The relative proportions of the surrogate components were determined so that the spray-related physical properties of the developed surrogate solutions, namely kinematic viscosity and surface tension, at room temperature resemble those of fast pyrolysis bio-oil (FPBO) at different fuel temperatures up to 80 °C. The rheological characteristics of both FPBO and its surrogate were measured in detail. They were then atomized using a twin-fluid nozzle at different co-flowing airflow rates, 6<Qa<16 L/min, to compare their atomization and spray performances. Similar breakup mechanisms and flow patterns were observed for them as a function of Qa. Furthermore, the number- and volume-based distributions of various sizes of droplets within the sprays exhibited similar behaviour, along with a higher uniformity at the fiber-type breakup regime in comparison with the non-axisymmetric Rayleigh and membrane-type breakup modes. The global Sauter mean diameter (SMD) and standard deviation (STD) of their sprays also showed similar trends based on Qa, albeit with some differences within 10% for the cases with proper atomization conditions. The discrepancies, which mainly stemmed from both the multiphase nature of FPBO and the dynamic behaviour of surfactant solutions, diminished at large values of the co-flowing air inertial forces. The practicality of the present approach in developing surrogates for the spray evaluation of viscous bioliquids is verified using the present study’s measurements and analyses.

Breakup regime and heat transfer of a vapor bubble within T-shaped branching microchannel

Understanding the transport characteristics and underlying mechanisms in microscale geometries is essential for microfluidic applications. While most fundamental studies in literatures focused on straight microchannels, the phase change process is still not fully understood for branching microchannels. In this study, a physically based high-fidelity numerical model is developed to investigate the breakup regime and phase change heat transfer of an isolated bubble within a T-shaped branching microchannel. The numerical model is first validated against both experimental data and numerical simulation in literatures, and a mesh independence study is performed to ensure the precision of the following simulations. Then, the influences of wall heat flux (50 W/m2 < q < 800 W/m2) and initial bubble size (0.64 < D* < 0.96) are investigated. Four distinct bubble breakup regimes can be recognized, namely non-breakup (NB) regime, “tunnel” breakup type one (TBⅠ) regime, “tunnel” breakup type two (TBⅡ) regime, and obstructed breakup (OB) regime. A phase diagram is plotted to describe the distribution of these regimes with respect to q and D*. The other important dynamic characteristics, such as two-phase flow structures, bubble deformation and growth are also investigated to help understanding the breakup process. In order to reveal the unique phase change heat transfer features within branching microchannel, the local heat transfer distribution and evolution are first quantitatively investigated on each channel wall, and then the influences of q and D* on the overall heat transfer performance are identified and compared with the single-phase heat transfer. The liquid film around the bubble and breakup dynamics are recognized as the key factors determining the phase change heat transfer performance within the microchannel and channel junction, respectively.

Effect of airflow pressure on the droplet breakup in the shear breakup regime

In this paper, the coupled level set volume of fluid and the large eddy simulation methods are adopted to perform three-dimensional simulations of the shear breakup of a water droplet. We investigate the effect of airflow pressure (1–3 atm) on the temporary deformation and breakup characteristics, including the breakup initiations, the cross-stream, and streamwise deformations. In addition, special attention is paid to subsequent sub-droplet size distributions, which are generally ignored by many researchers. The results indicate that different morphologies on the surface of the droplets in the shear breakup regime are in relatively good agreement with the available experimental visualizations. Based on the present method, the physical mechanism for the variations in the wake recirculation with the development of Rayleigh–Taylor instability waves is discussed. Furthermore, higher airflow pressures can significantly increase cross-stream and streamwise deformations. However, the corresponding breakup initiations at high airflow pressures are much earlier than those of parent droplets at low airflow pressures. Specifically, a reduction of 12.17% in the mean sub-droplet sizes is obtained as the airflow pressure increases from 1 atm to 2 atm, while a reduction of less than 0.1% in the mean sub-droplet sizes is obtained at higher airflow pressures from 2 atm to 3 atm. Eventually, there are linear growths of the aggregate superficial area ratios (0.996–28.2) and the mass ratios (3.55%–64.29%) of the sub-droplets to the parent droplet.

Regime mapping of multiple breakup of droplets in shear flow by phase-field lattice Boltzmann simulation

Multiple breakup refers to a sequence of events through which a single droplet eventually produces multiple daughter droplets in a shear flow. It is a more common phenomenon than binary breakup. Using a phase-field lattice Boltzmann method, this work investigates the effects of Reynolds number, capillary number and soluble surfactant on multiple breakup in shear flow. We find that the regime map for a droplet in a surfactant-free shear flow can be segmented into the non-breakup, elementary breakup, multiple breakup, filament and coalescence regimes. By contrast, the multiple-breakup regime widens and the coalescence regime narrows in the system of surfactant. This difference on macroscale regimes originates from the mesoscale behaviour caused by the interaction of surfactant and shear flow. While surfactant hinders droplet breakup at lower Re, it promotes breakup at higher Re. The interfaces around the breaking points are stretched by the opposite reaction of Marangoni stress. While the regime map gives the number of daughter droplets in a given shear flow, a correlation is proposed to calculate the composition of breakup events, viz. the number of binary breakup and of ternary breakup events.

DNS using CLSVOF method of single micro-bubble breakup and dynamics in flow focusing

Numerical simulations are performed to investigate the breakup of air bubble in flow focusing configuration; the CLSVOF (coupled level set with volume of fluid) method is employed to track the interface, which allows a better identification of the liquid–gas interface via a function called level set. The CFD simulations showed that the velocity ratio, the interfacial tension, the outer channel diameter, the continuous phase viscosity, the orifice width and length play an important role in the determination of the air bubble’s size and shape. However, at low capillary number, increasing the flow velocity ratio gives a smaller bubble size in shorter time, while the increase in interfacial tension leads to a bigger bubble. Moreover, the carrier fluid is found to slightly affect the bubbling mechanism, while the smallest bubbles were obtained with the smallest orifice size. In addition, three breakup regimes are observed in this device: disc-bubble (DB), elongated bubble (EB) and the slug bubble (SB) regime flows. This work also demonstrates that the CLSVOF is an effective method to simulate the bubbles breakup in flow focusing geometry. In addition, a comparison of our computational simulations with available experimental results reveals reasonably good agreement.

Experimental Investigations of Superheated and Supercritical Injections of Liquid Fuels

Abstract Single- and multicomponent liquid fuels are injected in a jet-in-coflow configuration at elevated temperatures and pressures with both a custom plain orifice nozzle and a commercial pressure-swirl atomizer. The transitions in spray morphology from mechanical breakup to superheated/supercritical regimes are characterized qualitatively by laser shadowgraphy and evaluated based on quantitative measures of superheat. Although fuel preheating exhibits no discernible effect in the mechanical breakup regime, dramatic jet-to-plume transition as well as build-up of fuel vapor in the spray chamber is observed with increasing level of superheat. The difference between two different atomizers in terms of spray behavior diminishes at high levels of superheat, suggesting the predominant role of thermal effect on spray morphology in superheated/supercritical regimes. For a mutlicomponent fuel such as Jet A-1, the transition into a fully flashing spray occurs at temperatures lower than expected values, which are calculated by treating Jet A-1 as a single-component fuel. Additionally, pressure drop is shown as a sensitive indicator for the departure from mechanical breakup and the onset of thermal effect on the spray. Comparisons between measured and estimated pressure drop also reveal the differences in susceptibility to thermal effects between the plain orifice and the pressure-swirl atomizers.

Single-pulse phase-contrast imaging at free-electron lasers in the hard X-ray regime

X-ray free-electron lasers (XFELs) have opened up unprecedented opportunities for time-resolved nano-scale imaging with X-rays. Near-field propagation-based imaging, and in particular near-field holography (NFH) in its high-resolution implementation in cone-beam geometry, can offer full-field views of a specimen's dynamics captured by single XFEL pulses. To exploit this capability, for example in optical-pump/X-ray-probe imaging schemes, the stochastic nature of the self-amplified spontaneous emission pulses, i.e. the dynamics of the beam itself, presents a major challenge. In this work, a concept is presented to address the fluctuating illumination wavefronts by sampling the configuration space of SASE pulses before an actual recording, followed by a principal component analysis. This scheme is implemented at the MID (Materials Imaging and Dynamics) instrument of the European XFEL and time-resolved NFH isperformed using aberration-corrected nano-focusing compound refractive lenses. Specifically, the dynamics of a micro-fluidic water-jet, which is commonly used as sample delivery system at XFELs, is imaged. The jet exhibits rich dynamics of droplet formation in the break-up regime. Moreover, pump-probe imaging is demonstrated using an infrared pulsed laser to induce cavitation and explosion of the jet.

Coriolis-induced liquid breakup and spray evolution in a rotary slinger atomizer: Experiments and analysis

Understanding the physics of primary liquid breakup process and its correlation with the evolution of spray characteristics in a rotary slinger atomizer is the goal of the present research. Experiments were conducted in a high-speed slinger test rig that houses a static liquid delivery manifold to uniformly supply the liquid to the rotating slinger disc that contains a single row of orifices carved on its peripheral surface for liquid injection.The atomizer was operated for a wide range of conditions by varying the rotational speed and liquid feed rate. The liquid breakup structure at the exit of the slinger orifices was visualized using front light illumination technique, while the droplet size was measured at different radial stations away from the slinger surface by application of the Interferometric Laser Imaging for Droplet Sizing (ILIDS) technique. The visualization images highlighted strong influence of Coriolis force as the liquid tends to accumulate on one side of the channel (that is opposite to the rotational direction) for all cases. It was observed that while the liquid thickness is smaller for higher rotational speed, it does not vary much with liquid feed rate at the same speed and, instead, in such case the span of the liquid is wider. A theoretical analysis was developed to describe the in-channel liquid behaviour that accounts for the effect of Coriolis and surface tension forces. Interestingly, the theory could explain the above observations. The differences in the predictions in comparison to the analysis by Dahm et al. (2006a) was attributed to the assumption of annular film flow in the latter. The liquid breakup mode (stream, sheet or transition mode) could be described by Coriolis Bond number (Bo) that refers to the ratio of Coriolis to surface tension forces and proportional to the spread parameter (span to thickness ratio), while the liquid breakup regimes were identified on a Bo−q plot, where q is the liquid to air momentum flux ratio. The variation of characteristic droplet sizes with both rotational speed and feed rate were examined, and again some interesting trends are identified. The correlation between liquid breakup mode/regime with the measured droplet size was established using the above non-dimensional numbers.

An experimental investigation on the secondary breakup of carboxymethyl cellulose droplets

Secondary breakup is a common phenomenon in nature, as well as in industrial applications. The secondary breakup of Carboxymethyl cellulose (CMC) droplets in a continuous air jet flow is investigated experimentally by a high-speed digital camera. Through varying the Weber number and the Ohnesorge number in the experiment, the breakup morphology, deformation stage, and breakup regime map are discussed in detail. The results show that the breakup modes of CMC droplet are consistent with that of water droplets in the Weber number range from 8 to 50 considered in the experiment. The number of nodes generated at the toroidal rim of the CMC droplet is verified to be the same as that of water droplet, following “the combined R-T/aerodynamic drag” mechanism. However, the breakup results of CMC droplets and water droplets are significantly different. The liquid ring and nodes produced by CMC droplets cannot disintegrate completely under the action of aerodynamic forces. In different breakup modes, the effective Ohnesorge number of CMC droplets has different influences on the cross stream diameter time-wise evolution and maximum deformation. The corresponding correlations for the above characteristics are developed in this paper. Finally, the breakup regime map of CMC droplets is produced by the Weber number and the effective Ohnesorge number.

Accelerating Taylor bubbles within circular capillary channels: Break-up mechanisms and regimes

In the present paper, an enhanced Volume of Fluid model is applied for the conduction of parametric numerical simulations, to investigate break-up phenomena of accelerating, elongated, vapour bubbles, within circular mini-channels. The effect of fundamental controlling parameters in the resulting break-up characteristics is investigated. Four different series of parametric numerical simulations of isolated vapour bubbles within mini-channels are performed, examining the effects of the imposed pressure difference between the inlet and the outlet of the channel, the surface tension, the effect of the applied heat flux as well as the initial liquid film thickness between the bubbles and the channel, on the developed vapour/liquid interface dynamics. The overall dimensionless number ranges examined are 6.76 < We < 1474.7, 0.007 < Ca < 0.14, 694 < Re < 12541 and by introducing a modified Froude number in order to account for the flow acceleration, 1 < Fr* < 21.86. These dimensionless number ranges are selected in order to overlap with experimental observations in zero-gravity Pulsating Heat Pipe experiments that constitute the motivation for the present numerical investigation. The proposed simulation results identify three prevailing regimes. A “full break-up” regime, a “partial break-up” regime and a “no break-up” regime. The entrainment of liquid droplets at the trailing edge of the vapour slugs is in most cases responsible for their subsequent “full break-up”, into a leading and a trailing bubble, as it is identified from the numerical simulations. Moreover, the applied heat flux does not influence the resulting break-up regimes. Finally, these identified break-up regimes, are grouped together into a well-defined flow map with respect to the We and Fr* numbers.

Effect of elevated pressure on air-assisted primary atomization of coaxial liquid jets: Basic research for entrained flow gasification

Highly resolved numerical simulations have been conducted for a generic, coaxial air-blast atomizer designed for fundamental research of entrained flow gasification processes. Objective of the work is to gain a detailed knowledge of the influence of elevated reactor pressure on the primary atomization behaviour of high-viscous liquid jets. In agreement with measured breakup morphology and breakup regimes proposed in literature, the simulations yield a pulsating mode instability of liquid jet, along with disintegrations of fibre-type liquid fragments for different pressures. From the mechanism point of view, the breakup process has been shown to be triggered by concentric, axisymmetric ring vortices, which disturb the liquid jet surface in a first stage and penetrate further into the intact core, leading to interfacial instabilities and pinch-off of liquid ligaments. The liquid jet breaks up faster at elevated pressure, leading to a shorter core length LC. The calculated exponent (b≈−0.5) of the power law for fitting the decrease of LC with p agrees well with measured correlations from literature in terms of varied momentum flux ratio M and Weber number WeG, although water jets, atmospheric pressure and different air-assisted, external mixing nozzles were used in these works. Therefore, the effect of elevated pressure is equivalent to that of increased M or WeG, which scale linearly with p or the gas density for the current setup. The specific kinetic energy of liquid kL has been found to be increased with p, which is particularly pronounced in the high frequency range. A first-order estimate has been proposed, which can be used for the evaluation of liquid kinetic energy or droplet velocity within the spray. The results have been validated by simulations with twice-refined resolution, yielding a grid-independence behaviour with respect to the primary breakup characteristics. However, the follow-up processes with secondary breakup and spray dispersion are reproduced better by using the finer grid.

Rupture process of liquid bridges: The effects of thermal fluctuations.

Rupture of a liquid bridge is a complex dynamic process, which has attracted much attention over several decades. We numerically investigated the effects of the thermal fluctuations on the rupture process of liquid bridges by using a particle-based method know as many-body dissipative particle dynamics. After providing a comparison of growth rate with the classical linear stability theory, the complete process of thinning liquid bridges is captured. The transitions among the inertial regime (I), the viscous regime (V), and the viscous-inertial regime (VI) with different liquid properties are found in agreement with previous work. A detailed description of the thermal fluctuation regime (TF) and another regime, named the breakup regime, are proposed in the present study. The full trajectories of thinning liquid bridges are summarized as I→V→VI→TF→ breakup for low-Oh liquids and V→I→ Intermediate →V→VI→TF→ breakup for high-Oh liquids, respectively. Moreover, the effects of the thermal fluctuations on the formation of satellite drops are also investigated. The distance between the peaks of axial velocity is believed to play an important role in forming satellite drops. The strong thermal fluctuations smooth the distribution of axial velocity and change the liquid bridge shape into a double cone without generating satellite drops for low-Oh liquids, while for high-Oh liquids, this distance is extended and a large satellite drop is formed after the breakup of the liquid filament occurs on both ends, which might be due to strong thermal fluctuations. This work can provide insights on the rupture mechanism of liquid bridges and be helpful for designing superfine nanoprinting.

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

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.