Micro-explosion Characteristics Research Articles

Nanosizing and Al-Mg alloying effects of boron particles on combustion characteristics and energy release of B/JP-10 suspension fuel

Adding boron particles into JP-10 to prepare B/JP-10 suspension fuel can effectively improve the energy density and combustion heat of JP-10-based aviation fuel. However, the energy release of boron in B/JP-10 fuel has many challenges to overcome. In this study, micron-sized boron (Micro-B), nano-sized boron (Nano-B) and aluminum-magnesium-boron (AlMgB) alloy particles were added into JP-10 fuel to prepare suspension fuels. The effects of boron particle nanosizing and alloying on the combustion characteristics and energy release of B/JP-10 fuel are experimentally evaluated. These characteristics were achieved by investigating the combustion stage, flame structure, emission spectra, droplet evolution, micro-explosion, flame temperature, and morphology of residues. The results show that compared with Micro-B/JP-10, Nano-B/JP-10 droplets show better micro-explosion characteristics, shorter burning time, and better boron-oxygen reaction rate during the combustion process. The results of combustion flame temperature and emission spectrum show that Nano-B/JP-10 droplets burn better, which shows that nano-boron particles have better energy release characteristics. AlMgB/JP-10 droplets reduce the reaction temperature of boron and enhance the combustion of boron through the interphase interaction of Al and Mg into B. Compared with Micro-B/JP-10, it shows a higher combustion flame temperature and emission spectrum intensity, the boron-oxygen reaction rate is greatly improved, and react to form flaky crystals on the agglomerate surface, making it difficult for the shell to close, resulting in weak micro-explosion but effective energy release.

Enhanced micro-explosion to improve the yield of light oil in catalytic cracking of water-in-heavy oil emulsion prepared by continuous membrane emulsification

Membrane emulsification provides new ideas for improving the atomization performance of high viscosity heavy oil in catalytic cracking process, thereby improving the distribution of catalytic cracking products. A comprehensive understanding of the micro-explosion characteristics and catalytic cracking of low water content heavy oil emulsion is the key to the application of membrane emulsification technology in heavy oil catalytic cracking process. Therefore, different water droplet sizes and water content of heavy oil emulsion were controllably prepared by continuous membrane emulsification, and their micro-explosion characteristics and catalytic cracking performance were investigated. The evaporation of heavy oil emulsion droplets (water content over 3 vol%) only underwent the heat transfer stage and the fluctuating evaporation stage due to the strong micro-explosion. The micro-explosion delay time of emulsion droplets decreased from 2.631 to 0.434 s/mm2 with increased temperature (300–600 ℃), increased from 0.645 to 1.042 s/mm2 with increased water content (1–5 vol%), and increased from 0.642 to 1.237 s/mm2 with increased average droplet size (1.80–14.6 μm). The child droplets generated after micro-explosion were characterized, and the different heating behaviors were quantitatively distinguished by the average size of the child droplets. Additionally, the micro-explosion performance (i.e. child droplets size and strong micro-explosion probability) of emulsion droplets improved with increasing water content and average water droplet size, while it initially decreased and then increased when the temperature increased. Furthermore, the improvement of micro-explosion performance by membrane emulsification can increase the yield of light oil (up to a maximum increase of 10.82 %) and reduce the yield of coke (up to a maximum decrease of 5.99 %) in the heavy oil emulsion catalytic cracking.

Combustion and micro-explosion characteristics of biodiesel–ethanol–aluminum powder particles droplet under simulated air nitrogen–oxygen

Compared with aviation fuel, biodiesel has a smaller energy density, so the flight range of aircraft using biodiesel as aviation fuel is relatively short. Adding aluminum powder particles can significantly improve the energy density of fuel and then improve the flight range of aircraft, but the combustion characteristics of fuel will change after adding aluminum powder particles to fuel. In this experiment, a tubular furnace was used to simulate the ratio of nitrogen to oxygen in air, and the micro-explosion and combustion characteristics of BD60E40 droplet and BD60E40 droplet 10%AP (8 μm) under 700 and 750 °C were compared and studied by using moving droplet tracking technology. It is found that the greater the steam pressure inside the droplet, the greater the intensity of micro-explosion, and the greater the initial velocity of the secondary droplet after micro-explosion. In addition, it is found that the proportion of aluminum powder in droplets increases gradually during the combustion cycle, and the frequency and intensity of micro-explosion of droplets increase gradually. The instantaneous combustion micro-explosion intensity model and the average combustion intensity model were established. It was found that the average combustion micro-explosion intensity of droplets increased gradually with the increase in temperature through calculation.

Effect of CuO powder on the combustion and micro-explosion of Mg and Al12Mg17 particles

In this paper, the effects of CuO powder on the combustion and micro-explosion characteristics of Mg and Al12Mg17 were studied. A laser was used to ignite particles and a high-speed micro-camera was used to record the particle ignition, flame propagation, combustion and particle changes before and after micro-explosion. Moreover, emission spectra during combustion and combustion products were analysed. The results show that the addition of CuO contributes to the micro-explosion of Mg particles during combustion, but it is not conducive to the micro-explosion of Al12Mg17 particles. Meanwhile, whether Al12Mg17 particles or Al12Mg17/CuO particles, the radiation peaks during combustion mainly correspond to Mg or MgO, which means that the addition of CuO cannot promote the gas phase combustion of Al in Al12Mg17.

A study on puffing and micro-explosion characteristics of diesel/ethanol/tetrahydrofuran blend fuel droplets

ABSTRACT Tetrahydrofuran (THF) is a biofuel that can be added to improve the solubility of ethanol in diesel. To explore the effect of surfactants, the puffing and micro-explosion characteristics of ethanol diesel/THF (DTE) blend droplets are investigated experimentally in comparison to a counterpart blend of ethanol diesel/biodiesel (DBE). Results show that with a rise in temperature, the puffing delay time decreases rapidly opposite to the fluctuation ratio; however, the puffing delay time rises with the ethanol content, whereas the fluctuation ratio remains about constant. Moreover, the tetrahydrofuran mainly participates in the early evaporation stage resulting in more prone to the edge mode for DTE droplets, which is in contrast to the DBE droplets, which prefer the inner mode. The micro-explosion strength of DTE droplets is lower than that of DBE due to the more likely occurrence of the edge mode, but the corresponding growth rate of DTE (15.2%, 25.4%, and 56.8%) with temperatures of 573 K, 623 K, and 723 K is higher than that of DBE droplets (8.8%, 20.4%, and 48.7%). A numerical model is also established for the present blend droplets, and the simulations reveal that the THF may additionally influence the heat absorption by the liquid and hence the superheat point of ethanol, which is responsible for the bubble formation and the micro-explosion.

Laser-Induced Ignition and Combustion of Single Micron-Sized Al-Li Alloy Particles in High Pressure Air/N2

To solve the problems associated with micron-sized aluminum (Al), including sintering, agglomeration, and slag deposition during the combustion of aluminized propellants, aluminum–lithium (Al-Li) alloy, prepared by introducing a small amount of Li (1.0 wt.%) into Al, was used in place of Al. Then, the ignition and combustion characteristics of single micron-sized Al-Li alloy particles were investigated in detail using a self-built experimental apparatus and multiple characterization methods. The ignition probability, ignition delay time, flame propagation rate, burn time, combustion temperature, flame radiation spectra, and microexplosion characteristics were obtained. The TG-DSC results demonstrated that, as compared to the counterpart Al, the Al-Li alloy had a lower ignition temperature. The emission lines of AlO revealed the gas-phase combustion of the Al-Li alloy, and thus the Al-Li alloy exhibited a mixed combustion mode, including surface combustion and gas-phase combustion. Moreover, during combustion, a microexplosion occurred, which increased the combustion rate and reduced the burn lifetime. The ambient pressure had a significant effect on the ignition and combustion characteristics of the Al-Li alloy, and the ignition delay time and burn time exponentially decreased as the ambient pressure enhanced. The combustion temperature of the Al-Li alloy at atmospheric pressure was slightly higher than those at elevated pressures. The Al-Li alloy burned in N2, but no microexplosion was observed. Finally, the ignition and combustion mechanism of the Al-Li alloy in air was demonstrated by combining SEM, EDS, and XRD analyses of the material and residues. The results suggest that the addition of Li promoted the combustion performance of Al by changing the surface structure of the oxide film and the combustion mode.

Experimental study on nucleation and micro-explosion characteristics of emulsified heavy fuel oil droplets at elevated temperatures during evaporation

The application of emulsified fuels can improve atomization quality which mainly benefits from the micro-explosion phenomenon. To explore bubble behaviors and droplet micro-explosion characteristics of emulsified heavy fuel oil (HFO) droplets during evaporation, the suspended droplet method was adopted. A water content of 0–30 % was used at atmospheric pressure and ambient temperatures of 573–873 K. Three trigger conditions for heterogeneous nucleation in the emulsified HFO droplet were proposed based on the properties of emulsified HFO. The dual-mode micro-explosion of emulsified HFO was defined as local and global micro-explosion. It is of great interest to mention that dual-mode micro-explosion accompanied by a honeycomb-like structure was clarified for the first time. Based on the experimental results, the working conditions of the droplet breakup modes and the appearance of a honeycomb-like structure were summarized. A regression formula was introduced to express the dependence of micro-explosion intensity on ambient temperature and water content. The temperature characteristic curve of the evaporation process presented an obvious plateau, which was a typical feature of emulsified HFO droplets in the evaporation process. Secondary droplets that entrapped bubble nuclei inside were also captured with an occurrence of droplet micro-explosion. This experimental investigation on bubble behaviors and micro-explosion characteristics during evaporation is expected to provide guidance for the application of emulsified HFO.

Investigation of single drop evaporation characteristics of two-component fatty acid methyl esters at high temperature

To investigate the evaporation and micro-explosion characteristics of blended droplets at 773 K and 973 K ambient temperatures, methyl palmitate (MP) and methyl oleate (MO) are selected as typical fuels in this study. The MP concentration ranges from 10 % to 50 % to investigate the micro-explosion characteristics of the blended droplets. No micro-explosion that occurs during its whole lifetime when MP is pure, but the micro-explosion can be observed in all blended droplets. Interestingly, the micro-explosion intensity, average evaporation rate, micro-explosion delay time, and evaporation duration of droplet all reach the optimum value when the MP concentration is 20 % at 773 K and 973 K. The micro-explosion can be divided into three categories by intensity, namely strong micro-explosion, weak micro-explosion, and puffing. The strong micro-explosions occur at 973 K when the concentration is 20 %. It can be inferred that micro-explosion is the critical factor in shortening the evaporation duration. Cleavage reaction that occurs in the MO produced bubbles to increase the micro-exploration intensity. Meanwhile, the polymerization that carried out in the MO inhibits the evaporation with producing solid. It is observed experimentally that the residual volume caused by the polymerization decreases with increasing MP concentration. Furthermore, a new relationship is established in terms of the evaporation rate, micro-explosion intensity and ambient temperature by numerical fitting.

Micro-explosion characteristics and mechanism of multi-component fuel droplet with high volatility differential

Micro-explosion is considered as one of the effective ways to improve atomization, combustion and reduce emissions. The present study examined the micro-explosion characteristics and mechanism of multi-component fuel droplets using fiber-support method and high-speed backlit imaging technique. The multi-component fuel blends consist of 2, 5-dimethylfuran (DMF) as a lower volatile component, while Jatropha oil is used as the higher volatile constituents. The results show that the micro-explosion modes are categorized as puffing, breakup + puffing, vapor jetting, jetting + puffing according to the single micro-explosion intensity and droplet breakup index. The breakup + puffing mode is the dominant mode, and the jetting + puffing mode only appears in droplets with 25/75 and 50/50 composition. The formation mode of secondary droplets includes short-wave mode and long-wave mode. Two types of bubble formed during Jatropha oil/DMF blended droplets micro-explosion: bubbles caused by DMF superheating and bubbles caused by fatty acid pyrolysis. Moreover, the diameter and the velocity of secondary droplets obey Lorentz distribution and Weibull distribution respectively. The micro-explosion of Jatropha oil droplets experienced bubbles nucleation, bubbles growth, bubbles coalescence, bubbles movement and fragmentation, which are mainly caused by the pyrolysis of fatty acids. However, the micro-explosion of Jatropha oil/DMF blended droplets presents two mechanisms according to the different DMF content. The low DMF concentration leads to formation of a layer of Jatropha oil film on the droplet surface first, and then goes through a similar process with Jatropha oil droplets. The high DMF concentration leads to formation of a layer of DMF film on the droplet surface first. Then go through the same process as high DMF concentration.

Experimental study on the evaporation characteristics of Jatropha curcas oil methyl ester (JME)-ethanol blended droplets

The evaporation and micro-explosion characteristics of Jatropha curcas oil methyl ester (JME) at 10%, 20%, and 30% ethanol by volume at two ambient temperatures were investigated using droplet evaporation experiments. The effects of different temperatures and ethanol content on parameters such as the normalized square diameter of droplets, micro-explosion intensity, number of micro-explosions, droplet evaporation duration and evaporation rate were analyzed. The experimental results show that adding ethanol component to the JME droplets increases the droplet expansion micro-explosion, and increasing ambient temperature promotes the droplet micro-explosion intensity and the number of micro-explosions. The intensity and number of micro-explosions of blended droplets are related to the concentration of ethanol. In addition, the micro-explosion intensity is numerically divided into strong micro-explosion and weak micro-explosion. Different concentrations of ethanol improve the evaporation characteristics of droplets differently. In general, the higher the concentration of ethanol, the shorter the droplet evaporation duration and the greater the evaporation rate. It was found that increasing the ethanol concentration from 20% to 30% had the most significant effect on droplet duration. Notably, the phenomenon of vapor clouds due to non-isothermal condensation caused by Stefan outflow was discovered.

Understanding of Contradiction on Concentration Effect on Stability, Physical Properties, Evaporation and Microexplosion Characteristics of Al/JP-10/Oleic Acid Nanofluid Fuel.

An Al/JP-10/oleic acid nanofluid fuel system has demonstrated potential in advanced combustion for aviation turbine engines. To improve the energy density of nanofluid fuel, a higher Al concentration requirement needs to be met. Correspondingly, a higher surfactant oleic acid concentration is required to maintain better dispersion stability. The increment of Al and oleic acid concentrations results in more frequent microexplosions, but a slower evaporation rate. Therefore, this paper proposes to deeply understand the contradiction of the concentration effect on the stability, physical properties, evaporation and microexplosion characteristics and obtain the best Al and oleic acid concentrations to maintain the most suitable comprehensive performance. Experiments on the stability, physical properties, evaporation and microexplosion characteristics were conducted, respectively. The analysis and discussion were then made to reveal the Al and oleic acid concentration effect on the stability, physical properties, evaporation and microexplosion characteristics. The results show that the optimum mass ratio of Al:oleic acid is 1:2 for the nanofluid fuels with Al concentrations of 2.5 wt.% or below, 1:2.5 for 5.0 wt.% or above to obtain the best stability. The physical properties of the nanofluid fuels such as density, surface tension and viscosity are linear, quartic and quadratic functions of Al concentration, respectively, relating to the internal flow and microexplosion of fuel droplets. With increasing oleic acid and Al concentration, the evaporation rates reduced, and the microexplosions became more frequent and intense. At a high ambient temperature of 600 °C, the evaporation rates were kept almost equivalent for JP-10, JP-10/oleic acid, and Al/JP-10/oleic acid fuels. It was found that the increment of ambient temperature can compensate for the reduction of the evaporation rate owing to the addition of oleic acid and Al nanoparticles, improving the evaporation and microexplosion performance.

Evaporation, Autoignition and Micro-Explosion Characteristics of RP-3 Kerosene Droplets under Sub-Atmospheric Pressure and Elevated Temperature

The evaporation, autoignition and micro-explosion characteristics of RP-3 kerosene droplets under sub-atmospheric pressure (0.2–1.0 bar) and elevated temperature (473–1023 K) were experimentally investigated using high-speed camera technology. The results showed that the droplet evaporation rate increased monotonically with increasing temperature and pressure under 573–873 K and 0.2–1.0 bar. The decrease of temperature and pressure was obviously detrimental to the successful autoignition of droplets and increased the ignition delay time. Autoignitions at 0.2 bar were very difficult and required an ambient temperature of at least 973 K, which was about 150 K higher than the minimum ignition temperature at 1.0 bar. Sub-atmospheric pressure environment significantly inhibits the formation of soot particle clusters during the autoignition of droplet. Reducing pressure was also discovered to reduce the likelihood of micro-explosions at 673, 773 and 823 K but increase the bubble growth rate and droplet breakage intensity. Strong micro-explosions with droplet breakage time close to 1 ms were observed at 0.6 bar and 773/823 K, showing the characteristic of bubble inertia control growth.

Experimental study on the micro-explosion characteristics of biodiesel/1-pentanol and biodiesel/ methanol blended droplets

Alcohols and biodiesel are promising alternative biofuels for their excellent physicochemical properties and renewable property. Compared with low-carbon alcohols, high-carbon 1-Pentanol has better fuel characteristics. The objective of the present study was to reveal the effects of different 1-pentanol addition ratios on the micro-explosion characteristics of blended droplets. Single droplet suspension experiment under atmospheric pressure and 700 °C was carried out, and results were compared with that of methanol. The droplet had three initial diameters (1.281, 1.451, and 1.537 mm). The droplet evaporation images were recorded at 500 fps with a resolution of 1024 × 1024 pixels by a high-speed video camera, and the corresponding droplet diameter in the evaporation process was obtained by a MATLAB program. A new dimensionless micro-explosion intensity was proposed. The results showed that when the 1-pentanol volume content was 50% (B50P50), the micro-explosion number and total micro-explosion intensity reached the maximum. With the increase of initial droplet diameter, the micro-explosion number, total micro-explosion intensity and droplet lifetime increased. Compared with biodiesel/1-pentanol blended droplets, biodiesel/methanol ones had better micro-explosion characteristics and shorter droplet lifetime. White fog formed in the evaporation process of blended droplets and pure biodiesel ones. In short, the addition of methanol and 1-pentanol caused micro-explosions, changed the evaporation behavior of biodiesel, and reduced droplet lifetime, which could be considered as an alternative fuel blended with biodiesel.

Comparison of combustion and micro-explosion characteristics of droplet group of biodiesel/ethanol and biodiesel/RP-3/ethanol

In order to compare the influence of temperature on the micro-explosion intensity and frequency of BD60E40 droplet group (the ratio of biodiesel to ethanol was 60:40) and BD60R10E30 droplet group (the ratio of biodiesel, RP-3, and ethanol was 60:10:30), a five-droplet synchronous heating experimental system was established. Using this experimental system, the heating sequence experiments of BD60E40 droplet group and BD60R10E30 droplet group in the range of 500–800 °C were carried out under simulated atmospheric conditions. By adjusting the ambient temperature, not only the ignition and expansion of the droplet group were found, but also the supermicro-explosion phenomenon was observed. In the experiment, the life cycle of droplet group had different characteristics under different temperatures and the life cycle of BD60E40 droplet group was calculated under 500–800 °C. The characteristics and reasons of BD60E40 droplet group life cycle changing with temperature were analyzed. Furthermore, the frequency model of supermicro-explosion of droplet group was established and calculated, and the influence of combustion on supermicro-explosion was analyzed. Furthermore, the reason for the difference of micro-explosion intensity between BD60E40 droplet group and BD60R10E30 droplet group was compared and analyzed.

Experimental study on the micro-explosion characteristics of two blended types of droplets under different nitrogen flow rates

Using the single droplet suspension method, the effect of nitrogen flow rate on the micro-explosion characteristics of L/H (low-boiling fuel in high one) and H/L (high-boiling fuel in low one) droplets in the laminar flow regime at 700 °C and atmospheric pressure was studied. The experimental results showed that for B80P20 (80% biodiesel and 20% 1-pentanol by volume) and B20P80 (20% biodiesel and 80% 1-pentanol), the micro-explosion intensity as well as the number of micro-explosions and strong micro-explosions increased first and then decreased with the increase in the nitrogen flow rate. In addition, the change range of B20P80 was always larger than that of B80P20. The micro-explosion intensity of B80M20 (80% biodiesel, 20% methanol) changed a little. However, for B20M80 (20% biodiesel, 80% methanol), it decreased monotonously with nitrogen flow rate. The variation of droplet lifetime was opposite to that of micro-explosion intensity except for B80M20. The micro-explosion delay time and relative micro-explosion delay time increased monotonously with nitrogen flow rate for B80P20, B20P80, and B20M80. As nitrogen flow rate increased, the micro-explosion distribution of B80M20 and B20M80 became more dense, but for B80P20 and B20P80, it became dense first and then sparse. In short, the nitrogen flow rate had a greater impact on H/L droplets than L/H ones, and a greater impact on B20M80 than B20P80. The experimental results provided a reference for further study on the micro-explosion mechanism of different blended types of droplets in different flow regimes.

Microexplosion Kinetics of Alcohol-Based Emulsified Biodiesel Droplets Evaporated in High Temperature

An alcohol-based emulsified fuel is formed by mixing ethanol, biodiesel, and water in different proportions. This fuel can be used in internal combustion engines to reduce fossil fuel consumption. In high-temperature environments, the microexplosion phenomenon of alcohol-based emulsified fuel can be observed directly. In this study, a high-temperature fuel evaporation test device was set up. The microexplosion process of alcohol-based emulsified fuel with varying water content (0%, 1%, 2%, and 3%) in different temperatures (773 K, 873 K, and 973 K) was studied by high-speed photography, and the data were analyzed by morphological treatment. To evaluate the microexplosion characteristics of alcohol-based emulsified fuel, some kinetic parameters—such as microexplosion delay, mean interfacial tension, number of bubbles, and mean microexplosion intensity—were proposed. The results show that the kinetic parameters put forward in this paper are reasonable for evaluating the microexplosion process. If the water content in the alcohol-based emulsified fuel is kept the same, the microexplosion delay decreases, while the mean interfacial tension increases with increasing temperature. If the evaporation temperature is kept the same, the microexplosion delay and the number of bubbles increase with the content of water increasing. Within the range of tested content of water and temperature, the mean microexplosion intensity of emulsion fuel is 0.05366 N·(m·s)−1 when the temperature is 973 K and the content of water is 3%, which is the largest.

Study on combustion and micro-explosion characteristics of biodiesel and ethanol mixture droplets under different oxygen concentrations and temperatures

An experimental platform for measuring droplet combustion and micro-explosion characteristics based on a tube furnace was established. Through this experimental platform, the BD60E40 droplets involving a mixture of 60 vol. % biodiesel and 40 vol. % ethanol was tested. Instantaneous gray images were obtained by means of high-speed photography during the BD60E40 droplets heating or combustion cycle. The expansion, ejection, micro-explosion, and combustion characteristics of mixed droplets under different temperatures and oxygen concentrations were studied by using the platform. The study found that the BD60E40 droplets produced high intensity primary and secondary micro-explosions when the oxygen concentration in the tube furnace was 0% and 30%. However, when the oxygen concentration was 50%, the BD60E40 droplet showed a weak micro-explosion phenomenon. The temperature was an important condition for the occurrence of micro-explosions. The BD60E40 droplet was not subject to micro-explosions during heating under 300 °C ambient temperature, but the micro-explosion occurred under 400 and 500 °C. According to the different experimental phenomena, the equation for calculating the micro-explosion intensity was established and the micro-explosion intensity of BD60E40 droplets under different oxygen concentration was calculated, and the reason for the different micro-explosion behavior of BD60E40 droplets under different oxygen concentration was established.

Experimental understanding on combustion and micro-explosion characteristics of mixed droplets of aviation fuel, biodiesel and ethanol

In order to explore the influence of different temperature and oxygen concentration on the combustion and micro-explosion of BD60R10E30 droplets (the ratio of biodiesel, aviation fuel and ethanol was 60:10:30), a set of volume measuring device was designed, and the volume of BD60R10E30 droplets with 1.34 μL was obtained by using this device, and a multi-parameter tube furnace experimental system was established. By adjusting the parameters of temperature and oxygen concentration, the experimental phenomena such as droplet ignition, expansion and micro-explosion were found, and the shape and boundary of discrete flame were firstly observed in mixed fuel. The modified micro-explosion intensity calculation model was established, and the micro-explosion intensity of mixed droplets under different conditions was calculated, and the reasons for the difference of micro-explosion intensity were analyzed. In addition, the concept of volume burning rate of micro-droplets was put forward, and the volume burning rate model based on micro-explosion intensity was established. The average volume burning rate of BD60R10E30 droplets under different micro-explosion intensity conditions was calculated by combining the micro-explosion intensity model with the volume burning rate model.

Numerical Simulation on Bubble Growth and Micro-explosion Characteristics of Biodiesel/ethanol Fuel Droplets

In this paper, the biodiesel/ethanol gas-containing fuel droplet was numerically simulated at room temperature. The growth characteristics of the bubble growth process were obtained, and the influencing factors affecting the bubble growth and micro-explosion process were explored. Studies have shown that bubble growth and droplet micro-explosion at room temperature are dominated by the pressure difference between the inside and outside of the bubble. Within a certain range, reducing the initial radius ratio of droplets as much as possible can also promote the bubble growth and micro-explosion of droplets. The proportion of fuel in the droplet will also affect the bubble growth and micro-explosion characteristics.

Experimental investigation on ignition, combustion and micro-explosion of RP-3, biodiesel and ethanol blended droplets

Based on an infusion set, measuring cylinder and different types of micro needles, a method for measuring the volume of micro-droplet was established. The same volume of aviation fuel (RP-3), biodiesel and ethanol mixed droplets were sent to a heatable experimental device to study the combustion characteristics. Through a movable slide rail with adjustable speed, the mixed droplets suspended on the high-temperature resistant wire were transported to a distance of about 2 mm from the preheating plug for heating. The ingle-lens-reflex (SLR) camera and a high-speed camera were used to capture the ignition characteristics and instantaneous combustion characteristics of mixed droplets during heating, respectively. The burning mixed droplets video captured by the SLR camera was processed into color pictures by Adobe Premiere Pro CC software. Through the processing and analysis of these images, the ignition, combustion and micro-explosion characteristics of mixed droplets during combustion were studied. The equation for calculating the micro-explosion intensity was established, the micro-explosion intensity of binary mixed droplets and ternary mixed droplets was calculated and analyzed.