Droplet Diameter Research Articles

Compact, high-flow, water-based, turbulent-mixing, condensation aerosol concentrator for collection of spot samples.

A new high-flow, compact aerosol concentrator, using rapid, turbulent mixing to grow aerosol particles into droplets for dry spot sample collection, has been designed and tested. The "TCAC (Turbulent-mixing, Condensation Aerosol Concentrator)" is composed of a saturator for generating hot vapor, a mixing section where the hot vapor mixes with the cold aerosol flow, a growth tube where condensational droplet growth primarily occurs, and a converging nozzle that focuses the droplets into a beam. The prototype concentrator utilizes an aerosol sample flow rate of 4 L min-1. The TCAC was optimized by varying the operating conditions, such as relative humidity of the aerosol flow, mixing flow ratio, vapor temperature, and impaction characteristics. The results showed that particles with a diameter ≥ 25 nm can be grown to a droplet diameter > 1400 nm with near 100% efficiency. Complete activation and growth were observed at relative humidity ≥ 25% of the aerosol sample flow. A consistent spot sample with a diameter of (the diameter of a circle containing 90% of the deposited particles) was obtained regardless of the aerosol particle diameter ( ). For fiber counting applications using phase contrast microscopy, the TCAC can reduce the sampling time, or counting uncertainty, by two to three orders of magnitude, compared to the 25-mm-filter collection. The study shows that the proposed mixing-flow scheme enables a compact spot sample collector suitable for handheld or portable applications, while still allowing for high flow rates.

Flow behavior and characteristic parameters of droplets in counter-current mini-channel extractor

Achieving the counter-current flow in mini-channel extractor is a challenge. The formation and characteristic parameters of droplets in mini-channel counter-current extractor were systematically investigated to provide a guide for the realization and operation of counter-current extraction. A mixture of P507 diluted with sulfonated kerosene was served as dispersed phase, while 0.2 mol/L LaCl3 solution was used as continuous phase. Droplets rapidly deformed from the nearly-spherical shape to ellipsoidal shape after detaching from nozzles, eventually floated upwards as monodisperse droplets with same spacing. Sauter mean diameter of droplets decreased with the increase of superficial velocity of organic phase, yet increased with the increase of superficial velocity of aqueous phase. The specific interfacial area of droplets increased with the increasing superficial velocity of organic phase, and slightly decreased with the increasing superficial velocity of aqueous phase. The correlations of droplet characteristic parameters were established using dimensional analysis for further prediction and analysis.

Dispersion Behavior of a Droplet Impacting a Single Fiber.

The high-gravity reactor, known for its excellent mass transfer capability, plays a crucial role in the carbon capture process. The wire mesh packing serves as the core structure for enhancing mass transfer performance. Understanding the underlying dispersion mechanism requires a thorough exploration of the dynamics of droplet impact on a single fiber. This work aimed to numerically study the process of a droplet impacting a single fiber by applying the volume of fluid method. The effects of initial velocity (u0), initial diameter (D0), impact eccentric distance (e), and impact angle (θ) on the deformation evolution and dispersion characteristics of a droplet impacting a single fiber were systematically studied. Central or vertical impacts can be categorized into four main stages: splitting, merging, stretching, and breaking. Meanwhile, asynchronous breaking, sliding splitting, and oblique stages were observed during eccentric and nonvertical impacts. Subsequently, dimensionless time (t*) and the rate of increase of the gas-liquid interfacial area (η) were introduced to quantitatively analyze the dispersion characteristics postimpact. Increasing the initial velocity, reducing the droplet diameter, minimizing the impact eccentric distance, and maximizing the impact angle all contribute to enhanced dispersion performance. A correlation for the maximum increase rate of the gas-liquid interfacial area of the droplet was proposed, with errors less than ±15%. Finally, the deformation mechanism of droplet impact on a fiber was summarized by analyzing the influences of differential pressure inside and outside the liquid film, as well as gas vortices.

Enhancing Bovine Embryo Development In Vitro Using Oil-in-Water Nanoemulsions as Specific Carriers for Essential Lipids.

Worldwide meat consumption and production have nearly quintupled in the last 60 years. In this context, research and the application of new technologies related to animal reproduction have evolved in an accelerated way. The objective of the present study was to apply nanoemulsions (NEs) as carriers of lipids to feed bovine embryos in culture media and verify their impact on the development of embryos produced in vitro. The NEs were characterized by particle size, polydispersity, size distribution, physical stability, morphology using atomic force microscopy (AFM), surface tension, density, pH, and rheological behavior. The NEs were prepared by the emulsification/evaporation technique. A central composite rotatable design (CCRD) was used to optimize the NE fabrication parameters. The three optimized formulations used in the embryo application showed an emulsion stability index (ESI) between 0.046 and 0.086, which reflects high stability. The mean droplet diameter analyzed by laser diffraction was approximately 70-80 nm, suggesting a possible transit across the embryonic zona pellucida with pores of an average 90 nm in diameter. AFM images clearly confirm the morphology of spherical droplets with a mean droplet diameter of less than 100 nm. The optimized formulations added during the higher embryonic genome activation phase in bovine embryos enhanced early embryonic development.

Emulsified oil-water separation properties of superhydrophobic/superoleophilic surface by emulsion droplets impacting dynamic behavior

Superhydrophobic/superoleophilic materials with excellent separation property are urgently needed for the clarification of water from oil-water emulsions, however, the lack of interfacial contact dynamics in the separation process is not beneficial to extensive application for them. Herein, a superhydrophobic/superoleophilic mesh was successfully prepared by spraying fluorinated polyurethane (FPU), silicon dioxide (SiO2) and carbon nanotubes (CNTs). The prepared mesh exhibited excellent superhydrophobic/superoleophilic performance, accomplishing a 1636.9 L m−2h−1 flux and a high separation efficiency above 99.8 % for water-in-oil (W/O) emulsions. The dynamic behavior of emulsion droplets impacting on the prepared mesh was innovatively investigated by experiment and simulation. As the oil content of emulsion droplets increased from 0 wt% to 2 wt%, the maximum spreading diameter (Ddmax) of emulsion droplets decreased from 5.57 mm to 5.28 mm, which can be attributed to the oil capture ability of the superhydrophobic/superoleophilic surface. Simultaneously, the maximum jet height (Hdamx) and the retraction velocity of the droplets firstly decreased and then increased. The results revealed that the oil film captured on the surface possessed good lubricity and water repellency, which could accelerate the dislodging of water from the surface and enhance separation performance. The separation mechanism of superhydrophobic/superoleophilic surface revealed by the contact dynamics study provided a novel path for the fabrication of emulsified oil-water separation materials.

A dynamic droplet breakup model for Eulerian-Lagrangian simulation of liquid-fueled detonation

This study proposes a dynamic model to reflect the physical image of the droplet breakup process in two-phase detonation flows. This breakup model is implemented in a two-phase detonation solver developed based on an open-source computational fluid dynamic platform, OpenFOAM, and compared with three prevalent models (TAB, PilchErdman, and ReitzKH-RT model) under different droplet diameters (30–70 μm) in one- and two-dimensional detonation problems. The simulating results show that the present breakup model well predicts experimentally determined detonation parameters such as detonation velocities and post-wave temperature. In addition, the present model has the advantage of being free of the KH breakup time parameter, which the ReitzKH-RT model needs to fit the experimental data. The one-dimensional detonation simulations indicate that different breakup models slightly impact the detonation wave velocity because the droplet breakup process does not significantly affect the total heat release as long as it is sufficiently fast to sustain the detonation. However, the two-dimensional detonation simulations show that the breakup model and the droplet initial diameter significantly affect the detonation cell size due to the different droplet distributions predicted by various models. The breakup length, which is the distance from the shock wave to the location at which sufficiently small child droplets appear, affects the chemical reaction zone thickness and then the detonation cell size. A longer breakup length will result in a larger detonation cell size.

Microfluidic study of effect of dispersed phase viscosity and continuous phase viscosity on emulsification in a cross-junction chip

Immiscible flow of oil phase and displacing phase with surfactant can cause emulsification during the oil development. However, it is still unclear how the viscosity of each phase influences the emulsification at the micro level. In this study, we investigated the flow regimes and emulsification of two immiscible fluids in a cross-junction device by using an oil-surfactant system and an oil-surfactant/polymer system. Based on the experimental data, we analyzed the flow regimes and draw flow regime maps of the two systems. Moreover, we established the new scaling laws that include the capillary number, the flow rate ratio, and the viscosity ratio of two phases to predict the droplet diameter or slug length. The findings indicated that there are four flow regimes in the oil-surfactant system, including threading, squeezing, dripping, and jetting regimes. Besides, a new type of flow regime, irregular dripping regime, appears in the oil-surfactant/polymer system. According to the regime maps, the area of dripping regime decreases with the increase of the viscosity of dispersed phase or continuous phase. For both systems, the regression equations with the viscosity ratio have better fitting effect than those without the viscosity ratio. Meanwhile, compared with the effect of viscosity ratio of two phases, the flow rate ratio of two phases has higher influence on droplet diameter and slug length. The experiments present detailed emulsification processes at pore scale and provide new insights for the prediction of emulsion droplets and slugs.

Icing characteristics of the superhydrophobic surface of gas turbine fairing

Abstract In order to investigate the mechanism underlying the impact of superhydrophobic surfaces on the icing and anti-icing characteristics of fairings, this study focuses on marine gas turbine fairings as the research subject and employs numerical simulation methods to examine how droplet diameter and impact velocity influence the icing characteristics of superhydrophobic surfaces on fairings. The findings reveal that larger droplet radii are more prone to freezing onto superhydrophobic surfaces, resulting in a more stable ice sheet formation. Moreover, higher droplet velocities facilitate easier freezing on superhydrophobic surfaces, leading to larger frozen areas, thicker ice sheets, and more pronounced ice peaks. Additionally, differences in impact angles prevent droplets from freezing.

Prediction of rain erosion damage progression using disdrometer rain data: The importance of liquid water content

Wind turbine blade erosion poses a significant challenge to the durability and performance of wind turbines. Modeling of rain erosion damage, considering atmospheric conditions, improves our understanding of the progression of leading-edge erosion on wind turbine blades. In this study, we investigate the impact of varying raindrop characteristics on rain erosion damage development. We analyse 2.5 years of data from a disdrometer, which measures the size and velocity of falling rain droplets, at Risø campus. Various post-processing methods of the disdrometer data are used for estimating representative droplet diameters and fall velocities for each rain event. We compare measured droplet fall velocities with theoretical terminal velocities, revealing a necessity for revising theoretical approaches to raindrop fall velocity for erosion damage modeling. The measured rain rates and representative fall velocities are used to calculate the liquid water content in the air. We introduce a bin-wise summation method for estimating the liquid water content, circumventing the need for representative droplet assumptions. As this method provides the most accurate input for the damage model, we benchmark the other post-processing methods against it and employ it to evaluate bias estimates of associated damage predictions. The largest bias (22%) in accumulated damage is found with an arithmetic mean droplet diameter approach and the smallest bias (-2%) with the median volume estimation method for damage model input. Furthermore, we demonstrate that, for a given rainfall volume, smaller droplets contribute to larger accumulated damage compared to larger droplets.

Dynamic evaporation characteristics of liquefied natural gas droplets

To delve into the intricate evaporation and dispersion mechanisms of dense droplets formed in the vicinity of liquefied natural gas (LNG) accidental releases, it is imperative to first examine the evaporation dynamics of individual moving LNG droplets. This paper presents a visual experimental setup designed to scrutinize the temporal evolution of diameter and displacement of single free-falling LNG droplets. Additionally, eight typical drag force models used for droplet motion state calculations were assessed. The optimal drag force models were selected to accurately predict the displacement of LNG droplets in the wide range of 100 < Re < 10 000. Moreover, eight typical gas phase models applied to predict heat and mass transfer were evaluated, revealing that none accurately capture the dynamic evaporation of free-falling LNG droplets. Subsequently, a new gas phase model suitable for predicting LNG droplet evaporation behavior is proposed. Furthermore, the periodic oscillation behavior of LNG droplet shape during the falling process is uncovered. The oscillation amplitude and dominant frequency of droplets are quantitatively investigated using the aspect ratio of droplets. Finally, an in-house program is developed to comprehensively analyze the evaporation characteristics of LNG droplets under different initial droplet diameters, velocities, and ambient temperatures. Based on gray relational analysis, the relative importance of three impacting factors on the evaporation coefficient is ranked.

Experimental study of dynamic behavior of impacting droplets on vibrating super-hydrophobic surfaces

The dynamic behaviors of droplets impacting on a vibrating solid surface are complex and interesting, as the differences in the initial phase angle can result in various droplet behaviors. The dynamic behavior of free-falling droplets impacting vibrating superhydrophobic substrates was investigated via high-speed photography. The effects of the initial phase angle (φ), Weber number (We), and vibration frequency (f) on the morphology evolution and energy dissipation were analyzed. Herein, 12 initial phase angles were selected as variables to investigate the evolution of droplet morphology with various initial phase angles. The effect of different initial phase angles on the maximum spreading diameter of droplets can cause variations of over 10%. The initial phase angles enhancing or restricting the droplet spreading were quantitatively defined. The Weber number and initial phase angle which can produce daughter droplets are obtained quantitatively. Meanwhile, a correlation between dimensionless spreading coefficient and dimensionless time was established for various vibration frequencies (f), revealing the effects of f on the maximum spreading diameter of droplet. Furthermore, a mathematical relationship for predicting the maximum spreading diameter of droplet impacting on a vibrating substrate was established based on the derivation of energy conservation. The error of the prediction mathematical model was proved to be less than 2% by the experimental results. These results provide fundamental understanding of droplet impacting on a vibration wall and could be useful for related engineering applications.

Digital droplet RT‐LAMP increases speed of SARS‐CoV‐2 viral RNA detection

AbstractNucleic acid amplification testing (NAAT) remains one of the most reliable methods for pathogen identification. However, conventional bulk NAATs may not be sufficiently fast or sensitive enough for the detection of clinically‐relevant pathogens in point‐of‐care testing. Here, we have developed a digital droplet RT‐LAMP (ddRT‐LAMP) assay that rapidly and quantitatively detects the SARS‐CoV‐2 viral E gene in microfluidic drops. Droplet partitioning using ddRT‐LAMP significantly accelerates detection times across a wide range of template concentrations compared to bulk RT‐LAMP assays. We discover that a reduction in droplet diameter decreases assay times up to a certain size, upon which surface adsorption of the RT‐LAMP polymerase reduces reaction efficiency. Optimization of drop size and polymerase concentration enables rapid, sensitive, and quantitative detection of the SARS‐CoV‐2 E gene in only 8 min. These results highlight the potential of ddRT‐LAMP assays as an excellent platform for quantitative point‐of‐care testing.

Microscopic spray characteristics of diethyl ether–diesel blends under single and split injection strategies

The phase doppler interferometry technique was used to thoroughly investigate microscopic spray characteristics of single and split injection strategies. The diethyl ether blending with diesel resulted in smaller and uniform droplet formation. Diethyl ether–diesel blend spray exhibited a lower droplet axial velocity distribution than baseline diesel, which can be improved by split injection strategies. At atmospheric pressure, the maximum axial velocity for diesel and diethyl ether–diesel blends was almost identical under single and split injection strategies. However, split injection improved the spray droplet's axial velocity at higher ambient pressures compared to single injection. The chances of coalescence and having coarse droplets were higher at elevated ambient pressure, especially for lower fuel injection pressures. Therefore, increasing the fuel injection pressure is more suitable to avoid droplet coalescence. Unlike the split ratio, dwell time strongly influenced fuel spray atomization. The droplet diameter distribution exhibited a higher probability of finer droplets for a longer dwell time of 0.45 ms than a shorter dwell time of 0.15 ms. A major finding of this study is that diethyl ether–diesel blend spray with a longer dwell time exhibited superior spray characteristics.

Corrosion of copper exposed to water-in biodiesel-diesel emulsion fuel stabilized with polyglycerol polyricinoleate emulsifier

Despite emulsification of water in-diesel can decrease harmful exhaust emissions, unstable emulsion can result in formation of free water which can accelerate metal corrosion in the fuel delivery system of a diesel engine. This study aimed to formulate and assess stability of 5 vol% water in 5 vol% biodiesel in diesel emulsion fuel (W5B5) and investigate its effects towards copper corrosion. Stable W5B5 was successfully prepared with 3 vol% polyglycerol polyricinoleate (PGPR). After 1200 h of storage, W5B5 remained stable, indicated by mean droplet diameter of 627.6 ± 7.5 nm, sedimentation index of ∼3 %, and absence of free water formation. Upon exposure to copper, mean droplet diameter of W5B5 increased by 2.7 times compared to prepared W5B5. Viscosity and total acid number (TAN) values of copper exposed W5B5 increased by 26 % and 270 %, respectively, indicating enlargement of water droplets and degradation of fuel during immersion. Corrosion rate of copper exposed to W5B5 decreased by 92 % between 240 and 1200 h of immersion. Corrosion rate of copper in W5B5 was 5.5 times and 3.0 times higher diesel and biodiesel, respectively. Higher initial TAN of W5B5 than other fuels, attributed to addition of PGPR to form stable water-fuel emulsion, influenced the higher corrosion rate observed in W5B5 compared to other fuels. To minimize corrosive nature of W5B5, future research should focus on developing stable formulation with low initial acidity value comparable to or even lower than biodiesel. The contribution to knowledge from the study yielded valuable insights into the stability of emulsion fuel, corrosion behaviour, and impact of emulsifier acidity on corrosion rates.

Fluidized catalytic cracking with novel emulsified feeding for increasing light oil yield and reducing additional CO2 emission

The fluid catalytic cracking unit (FCCU) is widely used in the processing of heavy oil. Fast and sufficient vaporization of heavy oil can maximize the light oil yield and reduce the coke yield. However, the inferior quality generally makes the heavy oil difficult to be vaporized. Unvaporized oil remaining on the catalyst surface will lead to high coke yield and subsequently high carbon dioxide emissions in the regenerator. The novel emulsified feeding technique can achieve secondary atomization of oil droplet through micro-explosion, which can reduce the droplet diameter and enhance the droplet vaporization. Computational Fluid Dynamics (CFD) simulation was performed to investigate the effect of emulsified feeding on the droplet vaporization and cracking reaction in the FCC riser reactor. It was found that when the reaction temperature is constant, the emulsified feeding can promote the droplet vaporization and cracking reaction. The average vaporization ratio can be improved by 1.2%-1.7%, and the light oil yield can be improved by 0.6%-0.8% compared to the conventional atomized feeding. The volume fraction of droplet near the side wall is largely reduced. The additional carbon emissions produced by unvaporized oil can therefore be reduced in the regenerator. In addition, the emulsified feeding technique will not have great impact on solids fluidization and pressure balance in the riser. The probability of micro-explosion of emulsion droplets is further discussed with respect to its effect on the vaporization and cracking reaction. The maximum light oil yield can be obtained with micro-explosion probability of 85%.

Simulation analysis of micro-explosion during emulsification feeding of residue fluidized catalytic cracking

Residue Fluidized Catalytic Cracking (RFCC) is one of the key processes to convert heavy oil into light products in refineries. The fast and sufficient vaporization of the feedstock in the FCC riser reactor can promote the catalytic cracking reaction and is beneficial for increasing the yield of light products and decreasing the yield of coke. However, fast vaporization of residue oil is extremely challenging due to its high density and viscosity. Recently, emulsified feeding technology is seen as a potential method that can effectively enhance the vaporization of RFCC feedstock. Computational Fluid Dynamics (CFD) simulations were performed in order to reveal the micro-explosion mechanism of emulsion droplet in the riser reactor. The CFD model was validated against experimental results from literature. The model was used to study micro-explosion of emulsified droplets in the gas phase and at the catalyst particle surface separately. It was found that due to the micro-explosion of emulsion oil droplets in producing large number of tiny droplets, the secondary atomization of droplets can be realized. In the gas phase, the interfacial area of emulsion droplet can be improved by 5 to 15 times. At the catalyst surface, the percentage of liquid film coverage was reduced by 32.6 %, and the droplet diameter was reduced by 92 % for the emulsified feeding technology. These results indicate that the vaporization efficiency of the residual oil can be greatly improved by this technology.

VOF based model of numerical simulation for single aluminum droplet evaporation and combustion

ABSTRACT This study investigates the combustion of a single aluminum droplet in a high-temperature convective setting, focusing on the interplay between the environment and droplet evaporation combustion. Using the VOF numerical method, a two-dimensional multiphase flow combustion model for micron-sized aluminum droplets is developed. Experimental validation compares predicted droplet diameter with experimental data. The combustion behavior of aluminum droplets in high-temperature convective environments is analyzed, emphasizing gas-phase combustion during stable stages. Parametric variations in flow velocity and oxygen concentration reveal the formation of vortices around the droplet, influencing aluminum vapor accumulation and evaporation rates. Combustion primarily occurs at the droplet’s windward side, with reaction rates decreasing downstream. Increasing gas velocity from 1.5 m/s to 3 m/s thins the aluminum vapor concentration boundary layer, boosting combustion rates by 35%. Elevating oxygen concentration from 20% to 50% brings the flame closer to the droplet, accelerating combustion rates by 2.7 times, suggesting oxygen concentration’s role in reaction acceleration and combustion duration reduction. This research offers insights for simulating aluminum droplets in propellant applications.

Gap in drop collision rate between diffusive and inertial regimes explains the stability of fogs and non-precipitating clouds

Rain drops form in clouds by collision of submillimetric droplets falling under gravity: larger drops fall faster than smaller ones and collect them on their path. The puzzling stability of fogs and non-precipitating warm clouds with respect to this avalanche mechanism has been a longstanding problem. How can droplets of diameter around 10 $\mathrm {\mu }$ m have a low collision probability, inhibiting the cascade towards larger and larger drops? Here we review the dynamical mechanisms that have been proposed in the literature and quantitatively investigate the frequency of drop collisions induced by Brownian diffusion, electrostatics and gravity, using an open-source Monte Carlo code taking all of them into account. Inertia dominates over aerodynamic forces for large drops, when the Stokes number is larger than $1$ . Thermal diffusion dominates over aerodynamic forces for small drops, when the Péclet number is smaller than $1$ . We show that there exists a range of size (typically 3–30 $\mathrm {\mu }$ m for water drops in air) where neither inertia nor Brownian diffusion are significant, leading to a gap in the collision rate. The effect is particularly important, due to the lubrication film forming between the drops immediately before collision, and secondarily to the long-range aerodynamic interaction. Two different mechanisms regularise the divergence of the lubrication force at vanishing separation: the transition to a non-continuum regime in the lubrication film, when the separation is comparable to the mean free path of air, and the induction of a flow inside the drops due to shear at their surfaces. In the gap between inertia-dominated and diffusion-dominated regimes, dipole–dipole electrostatic interactions becomes the major effect controlling the efficiency of drop collisions.

Component Effects in Binary Droplet Impact Behaviors on the Heated Plate: Comparison Study of Ethanol/Propanol and Ethanol/Water Droplets and Observation of Novel Bubble Shrinkage Phenomenon

This work aims to investigate the effect of liquid physical properties on the behavior of binary droplets impact on the heated smooth aluminum alloy plate with a high-speed imaging system. Two groups of mixed solutions with similar boiling point differences are selected as the working liquid, in which the low-boiling-point components are both ethanol and the high-boiling point components are propanol and water, respectively. Compared to the ethanol/propanol binary droplets, the experimental results show that the ethanol/water binary droplets have diverse impact phenomena and significantly broad transition boiling regimes, as well as the reduced droplet residence time and increased Leidenfrost temperature point. With the decreasing ethanol content in ethanol/water binary droplets, these effects become more prominent. For secondary atomization, the ethanol/water binary droplet undergoes parent droplet breakup into fragment droplets with larger diameters (Ds > 0.3 mm). Both binary droplets produce satellite droplets with small diameters (Ds < 0.3 mm) by puffing and ejection. In terms of the ethanol/propanol binary droplet impact, the probability of puffing is higher and the satellite droplet diameters are small. In the ethanol/water binary droplet impact, the probability of ejection is higher and the satellite droplet diameter distribution is wider. When an ethanol/water binary droplet of 25 vol.% ethanol content impacts the heated wall at Ts = 120 °C, a novel large bubble shrinkage phenomenon occurs at the late stage of droplet evaporation. This phenomenon is proposed to be relevant to the increasing surface tension and saturation temperature with decreasing ethanol content, as well as the decreasing ambient temperature above the top surface of the bubble.

Investigation of Spray Characteristics for Detonability: A Study on Liquid Fuel Injector and Nozzle Design

Detonation engines are gaining prominence as next-generation propulsion systems that can significantly enhance the efficiency of existing engines. This study focuses on developing an injector utilizing liquid fuel and a gas oxidizer for application in detonation engines. In order to better understand the spray characteristics suitable for the pulse detonation engine (PDE) system, an injector was fabricated by varying the Venturi nozzle exit diameter ratio and the geometric features of the fuel injection hole. Analysis of high-speed camera images revealed that the Venturi nozzle exit diameter ratio plays a crucial role in determining the characteristics of air-assist or air-blast atomization. Under the conditions of an exit diameter ratio of Re/Ri = 1.0, the formation of a liquid film at the exit was observed, and it was identified that the film’s length is influenced by the geometric characteristics of the fuel injection hole. The effect of the fuel injection hole and Venturi nozzle exit diameter ratio on SMD was analyzed by using droplet diameter measurement. The derived empirical correlation indicates that the atomization mechanism varies depending on the Venturi nozzle exit diameter ratio, and it also affects the distribution of SMD. The characteristics of the proposed injector, its influence on SMD, and its velocity, provide essential groundwork and data for the design of detonation engines employing liquid fuel.