Combustion Characteristics Research Articles

Analysis of Burn Casualties in the Swords of Iron War

Abstract The Swords of Iron (SOI) War is an armed conflict between Israel and Hamas, which has been taking place in Gaza from October 2023 until the present time of writing this article. This war is characterized by urban close contact combat. The combat equipment, weaponry, and protective measures employed, differ markedly from those in previously documented major conflicts, significantly impacting the types of injuries sustained by soldiers. This study examines the number of injured soldiers in combat, field mortality rates, incidence of burns and trauma, demographic details of the injured, causes and distribution of injuries, burn characteristics, hemodynamic status, and injury severity. This is a retrospective, registry-based cohort study. Military personnel treated by IDF medical teams with burn injuries from the ground maneuver in Gaza between October 27th, 2023 to April 2024 were included in the analysis. Diagnosis of burn injuries was made in the prehospital setting and recorded in the patient’s casualty cards and the IDF trauma registry and/or in the hospitals, and then recorded by the Israel National Trauma Registry. A total of 2,627 documented military personnel were included. Of them, there was a total of 249 burn casualties. They were all male combat soldiers and their mean age was 22 years. Most of the burn injuries were combined with other injuries, only 12% were defined as in shock state, and 14% received whole blood in the field. The burn degree was second and third degree for most cases. A third (34%) of burn injured soldiers had surgery (Table 2), and half of the total were sent to rehabilitation departments following their initial hospitalization. An analysis of total body surface area (TBSA)% affected by burns among SOI War casualties reveals a higher proportion of severe burns exceeding 20% TBSA, compared to previous conflicts. Additionally, a higher proportion of personnel suffered from second and third degree burns. This is likely attributed to the operational mode of the IDF in Gaza, where urban close-contact warfare exposes soldiers to heightened risks of explosive and blast injuries. A significant percentage of live casualties had TBSA percentages that were not life-threatening, which underscores the importance of updating emergency burn treatment protocols and employing rapid evacuation and medical response systems in the field. Most of the wounded that suffer from significant burns had other significant and life-threatening injuries, making the appropriate protective measures and the preparation for rapid evacuation the best way to improve burn casualty survival. The significance of this research lies in the timely analysis of accumulated combat data to derive lessons and conclusions relevant to ongoing and future conflicts, and to understand the clinical implications arising from combat situations. Given the relatively high prevalence of burn injuries, understanding their etiology, severity, and consequences is essential for developing effective prevention and treatment courses.

Numerical Simulation Study on the Stable Combustion of a 660 MW Supercritical Unit Boiler at Ultra-Low Load

To investigate the safe, stable, and economically viable operation of a boiler under ultra-low-load conditions during the deep peaking process of coal-fired units, a numerical simulation study was conducted on a 660 MW front- and rear-wall hedge cyclone burner boiler. The current research on low load conditions is limited to achieving stable combustion by adjusting the operating parameters, and few effective boiler operating parameter predictions are given for very low-load conditions, i.e., below 20%. Various burner operation modes under ultra-low load conditions were analyzed using computational fluid dynamics (CFDs) methods; this operation was successfully tested with six types of pulverized coal combustion in this paper, and fitting models for outlet flue gas temperature and NOx emissions were derived based on the combustion characteristics of different types of pulverized coal. The results indicate that under 20% ultra-low-load conditions, the use of lower burners leads to a uniform temperature distribution within the furnace, achieving a minimum NOx emission of 112 ppm and a flue gas temperature of 743 K. Coal type 3, with the highest carbon content and a calorific value of 22,440 kJ/kg, has the highest average section temperature of 1435.76 K. In contrast, coal type 1 has a higher nitrogen content, with a maximum cross-sectional average NOx concentration of 865.90 ppm and an exit NOx emission concentration of 800 ppm. The overall lower NOx emissions of coal type 3 are primarily attributed to its reduced nitrogen content and increased oxygen content, which enhance pulverized coal combustion and suppress NOx formation. The fitting models accurately capture the influence of pulverized coal composition on outlet flue gas temperature and NOx emissions. This control strategy can be extended to the stable combustion of many kinds of coal. For validation, the fitting error bar for the predicted outlet flue gas temperature based on the elemental composition of coal type 6 was 8.09%, whereas the fitting error bar for the outlet NOx emissions was only 1.45%.

Experimental Investigation of Ammonia/Oxygen/Argon Combustion: The Role of Equivalence Ratio and Nozzle Shape in a Constant Volume Combustion Chamber with Sub-chamber

The global rise in carbon emissions presents a rising challenge for current and future generations. In the pursuit of zero carbon emissions, ammonia (NH3) has emerged as an attractive alternative energy source. Ammonia offers a carbon-free fuel option with a higher energy density than liquid hydrogen while maintaining ease of transport and storage. However, ammonia still has its drawbacks, such as a high autoignition temperature, slow burning velocity, and low heating value, that demand further investigation of its combustion characteristics. This experiment was done to study the effect of nozzle shape and equivalence ratio (ɸ) on the combustion of an ammonia/oxygen/argon mixture using a constant volume combustor equipped with a sub-chamber. The fuels were premixed for 10 minutes and conditioned to an initial pressure of 0.2 MPa and an initial mixture temperature of 423 K. The results show that the different nozzle shapes each have their advantages in terms of pressure and jet speed. Overall, the lean mixtures (ɸ0.6 and ɸ0.8) consistently performed better compared to the stoichiometric mixtures (ɸ1.0) in all categories investigated in this study. The round nozzle generates higher pressure, while the special shape nozzle enhances jet speed, highlighting trade-offs between the two.

Impact of nano cerium oxide addition with pyrolysis waste plastic oil on combustion, performance and emission characteristics of CRDI diesel engine

Abstract This investigation examined the effect of incorporating cerium oxide (CeO2) nanoparticle into diesel and waste plastic oil (WPO) blends on the combustion, performance and emission characteristics of the diesel engine. The WPO was extracted from low density polyethylene using plastic pyrolysis. The blending of diesel and WPO with combination of D70:WPO30 and D50:WPO50 was prepared to evaluate the engine operation. Additionally, the spherical sized CeO2 with 50 mg/L and 100 mg/L was added with this blend. The various blends named as Diesel, D-WPO30, D-WPO30+Ce50, D-WPO30+Ce100, D-WPO50, D-WPO50+Ce50 and D-WPO50+Ce100 were used in this investigation to operate the engine under various load conditions. The experiment was performed using water cooled common rail direct injection (CRDI) diesel engine with prepared D-WPO blend. Different characteristics such as In-cylinder pressure (CP), heat release rate (HRR), ignition delay time (IDT), brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and exhaust gas temperature (EGT), carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NOx) and smoke opacity emission are studied with respect to the effect of different blends and applied load used. It was observed that increasing of CeO2 nanoparticles in blend improved the overall performance and emission of the engine. Form the results, D-WPO30+Ce100 blend showed enhanced brake thermal efficiency (BTE), brake specific fuel consumption (BSFC) and exhaust has temperature (EGT) are 28.2%, 3% and 465oC respectively. Similarly, reduced emission of CO, NOx, HC and smoke opacity was observed in the CeO2 added blends particularly at 100 mg/L. It was concluded that among all blends prepared, the D70:WPO30 with 100 mg/L of CeO2 showed improved combustion, performance and emission characteristics in proposed diesel engine.

Use of butanol, pentanol and diesel in a compression ignition engine: A review

Using oxygenated alternative fuels in compression ignition (CI) engines is feasible for energy security problems and cli-mate change. Alcohols are regarded as alternative fuels for compression ignition engines because of their excellent physi-cochemical features, emission, and combustion characteristics. Research on alcohols and their additions has progressed significantly in recent years. Several researchers have examined the combined effect of higher alcohol with diesel and their impact and challenged that concentrations of higher alcohol reduce harmful particulate emissions in CI engines. This paper mainly focused on the performance and emissions properties of higher alcohols like butanol and pentanol. Alcohol has a low energy content, typically affecting engine brake-specific fuel consumption (BSFC). Low-temperature combustion (LTC) in compression ignition engines can lower NOx and smoke emissions, and improve the efficiency of the engine. LTC is done by combining higher alcohol with increased exhaust gas recirculation (EGR) rate and retarded fuel injection timing. The higher alcohol, along with the oxygen in the fuel reduces exhaust fumes, improves the air/fuel mixture by providing a longer ignition delay (ID), and can replace the fossil fuel like diesel (partially or whole) to allow efficient and clean combustion in CI engines. Finally, several significant findings and comments are provided regarding potential ave-nues for experimental research and future development. According to thorough analysis, bio-alcohols are considered to be a substitute fuel for CI engines.

Effect of Nozzle Type on Combustion Characteristics of Ammonium Dinitramide-Based Energetic Propellant

The present study explores the influence of diverse nozzle geometries on the combustion characteristics of ADN-based energetic propellants. The pressure contour maps reveal a rapid initial increase in the average pressure of ADN-based propellants across the three different nozzles. Subsequently, the pressure tapers off gradually as time elapses. Notably, during the crucial initial period of 0–5 μs, the straight nozzle exhibited the most significant pressure surge at 30.2%, substantially outperforming the divergent (6.67%) and combined nozzles (15.5%). The combustion product variation curves indicate that the contents of reactants ADN and CH3OH underwent a steep decline, whereas the product N2O displayed a biphasic behavior, initially rising and subsequently declining. In contrast, the CO2 concentration remained on a steady ascent throughout the entire combustion process, which concluded within 10 μs. Our findings suggest that the straight nozzle facilitated the more expeditious generation of high-temperature and high-pressure combustion gases for ADN-based propellants, expediting reaction kinetics and enhancing combustion efficiency. This is attributed to the reduced intermittent interactions between the nozzle wall and shock waves, which are encountered in the divergent and combined nozzles. In conclusion, the superior combustion characteristics of ADN-based propellants in the straight nozzle, compared to the divergent and combined nozzles, underscore its potential in informing the design of advanced propulsion systems and guiding the development of innovative energetic propellants.

Numerical Study on Combustion Characteristics of a 600 MW Boiler Under Low-Load Conditions

Under the background of achieving carbon dioxide peaking and carbon neutrality, the rapid development of renewable energy power generation poses new challenges to the flexible adjustment capabilities of traditional power plants. To explore the furnace combustion stability and optimal operation modes during deep peak shaving, a simulation of the combustion process under low-load conditions for a 600 MW wall-fired boiler is performed utilizing computational fluid dynamics (CFD) analysis. The impact of burner combination modes on the combustion process within the furnace is explored at 25% and 35% boiler maximum continuous ratings (BMCRs). This study investigates two configurations of burner combinations. One mode operates burners in layers A, B, and C, which include the lower layers of burners on the front and rear walls of the boiler, as well as the middle-layer burners on the rear wall, referred to as OM1. The other mode operates burners in layers A and C, which include the lower layers of burners on the front and rear walls of the boiler, referred to as OM2. The results indicate that OM2 exhibits superior capabilities in orchestrating the distribution of the airflow velocity field and temperature field under the premise of ensuring no more than a 1% decrease in the pulverized coal burnout rate. When OM1 is employed, the airflow ejected from the middle-level burners hinders the upward movement of pulverized coal sprayed from the lower-level burners, causing a larger proportion of pulverized coal to enter the ash hopper for combustion. Consequently, the ash hopper attains a peak mole fraction of CO2 at 0.163. OM2 delays the blending of pulverized coal with air by enhancing the injection quantity of pulverized coal per burner. As a result, the generation of CO in the ash hopper reaches a notable mole fraction of up to 0.108. The decreased furnace temperature promotes the formation of fuel-based NOx during low-load operation. Taking the 25% BMCR as an example, the NOx emissions measured at the furnace outlet are 743 and 1083 ppm for OM1 and OM2, respectively. This study focuses on the impact of combustion combinations on the combustion stability when the boiler is operating at low loads. The findings could enrich previous research on combustion stability and contribute to the optimization of combustion schemes for power plant boilers operating at low loads.

Experimental Study on the Effect of Ammonia on Combustion and Emission Characteristics of a Spark Ignition Engine Fueled with Hydrogen

Experimental Study on the Effect of Ammonia on Combustion and Emission Characteristics of a Spark Ignition Engine Fueled with Hydrogen

A comprehensive investigation of the impact of carbon-supported metal complexes of triaminoguanidine on the characteristics of a double-base propellant

ABSTRACT In this study, triaminoguanidine complexes grafted onto activated carbon (AC-TAG-Fe and AC-TAG-Co) were designed and investigated for their catalytic effect on the thermolysis of a double base propellant consisting of nitrocellulose (NC) and diethylene glycol dinitrate (DEGDN). The successful synthesis of transition metal complexes with triaminoguanidine and their subsequent grafting onto activated carbon were confirmed using various analytical techniques, including Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, X-ray Diffraction, and Scanning Electron Microscopy. Thermal characterization using Thermogravimetric Analysis and Differential Scanning Calorimetry provided valuable insights into the thermal properties and reactivity of the elaborated NC/DEGDN-based composites. Importantly, the addition of various additives resulted in notable improvements in both the enthalpy of reaction and density. Isoconversional kinetic studies revealed that the incorporation of TAG-Fe and TAG-Co complexes reduced the apparent activation energy of the NC/DEGDN composite from 137.4 kJ/mol to 135.4 kJ/mol and 114.8 kJ/mol, respectively, suggesting their catalytic effect. Furthermore, it is found that the addition of activated carbon (AC) resulted in an increase in activation energy to 154 kJ/mol, whereas grafting TAG-Fe and TAG-Co complexes onto AC as a catalytic support subsequently reduced activation energy to 119 kJ/mol and 112 kJ/mol, respectively. Overall, this research serves as a valuable reference for future studies focusing on investigating the catalytic combustion characteristics of double-base solid propellants.

Assessment of the use of biochar from the slow pyrolysis of walnut and almond shells as an energy carrier

ABSTRACT This study explores the energy applications and combustion kinetics of biochar produced from walnut and almond shells through pyrolysis. Using macro-thermogravimetric analysis at heating rates of 10, 15, and 20 K min−1, a multi-step mechanism involving two parallel reactions was used to model thermal decomposition. Bioenergy indices revealed that walnut shell-based biochar (WSB) produced at 773 K and 873 K displayed superior biofuel potential due to its high energy density and low ash content, while almond shell-based biochar (ASB) at 673 K demonstrated the best overall bioenergy performance. Among the tested heating rates, 15 K min−1 provided optimal results for ignition, combustion, and burnout indices, with WSB showing the highest overall combustion performance. Kinetic analysis using the Coats-Redfern method demonstrated the highest R2 values and minimized RMSE and SSE. The activation energy for the first pseudo-component ranged from 54.91 to 129.84 kJ mol−1 for ASB and from 61.71 to 141.85 kJ mol−1 for WSB. For the second pseudo-component, the activation energy ranged from 25.21 to 159.32 kJ mol−1 for ASB and 25.63 to 96.25 kJ mol−1 for WSB. These findings emphasize the potential of WSB and ASB biochar for bioenergy applications, with WSB exhibiting the best combustion characteristics.

Investigation on CuO nanoparticle enhanced mahua biodiesel/diesel fuelled CI engine combustion for improved performance and emission abetted by response surface methodology

In this study, the characteristics of diesel engines were tested with in-house produced mahua biodiesel blended with diesel and copper oxide nanoparticles (CuO NP) catalyst. The preliminary investigation used mahua biodiesel-diesel blends (M10, M20, and M30) among them M20 outperformed. Further M20 and CuO NP with concentrations of 25, 50, and 75 ppm are studied. Finally, the response surface methodology (RSM) was used to determine the appropriate NP concentration for M20. The findings showed that the blend of M20 with 60 ppm NP at 80% load had the highest desirability (0.9740), and the developed RSM model predicted engine responses with a mean absolute percentage error (MAPE) of 3.0962% to the confirmation test confirming the model’s accuracy. The optimized M20NP60 blend demonstrated superior combustion, performance and emission characteristics.

Research on the implementation of free piston engine generator at various compression ratios and combustion performance of multiple fuels

The Free Piston Engine Generator (FPEG) is a novel energy conversion system that directly couples a free piston engine with a linear generator. Its ability to adjust the compression ratio over a wide range without complex auxiliary structures and its adaptability to different fuels have garnered significant attention. To improve the efficiency and cleanliness of FPEG, This study employs an FPEG prototype test bench, using ethanol and n-propanol as raw materials, mixed with aviation kerosene (RP-3) at volume ratios of 20 %, 40 %, and 60 %, respectively. It investigates the impact mechanisms and operating characteristics of different running parameters on the compression ratio of FPEG when using different fuels, and to analyze the combustion and emission characteristics of FPEG under various compression ratio conditions. The results show that compared to gasoline, the alcohol/RP-3 mixtures (with alcohol content >40 %) have higher brake thermal efficiency and significantly reduced CO emissions. As the compression ratio increases, the brake thermal efficiency of alcohol/RP-3 mixtures further improves, while CO and HC emissions decrease. At higher compression ratios, the n-propanol/kerosene blends show higher efficiency and lower CO and HC emissions. These findings provide important insights into the multi-fuel application of FPEG and the potential for cleaner energy conversion.

Boron/Difluoroamino (B/NF2) Composites Prepared Through an Energetic Fluorinated-Centerd Surface Modification Strategy to Enhance Their Ignition and Combustion Characteristics

To enhance the ignition and combustion characteristics of boron (B), in this study, a suitable, energetic fluorinated group (NF2) that can improve energy and promote combustion efficiency was utilized and B/NF2 composites (B/PDB) with three different particle sizes (10–20 μm, <5 μm, and 0.5–2 μm) were prepared through energetic fluorinated surface modifications with a PDB layer, a copolymer of difluoroaminomethyl-3-methylethoxybutane and 3,3′-bis(azidomethyl)oxetane, coated on the surface of B. The morphology and structure of B/PDB were characterized via the FTIR, SEM, TEM, and XPS techniques. The results indicate that all B/PDB particle sizes were successfully coated by NF2 on the surfaces of B particles through the PDB layer. The TG curves in the thermal analyses were used to determine the amount of the PDB layer of B/PDB with different particle sizes. Based on the DSC curves, NF2 of composites with better catalysis during ammonium perchlorate (AP) decomposition. Additionally, the effects of NF2 on both B/PDB and B/PDB with AP were investigated through PY-GC/MS, ignition, and combustion. Compared with pure B, NF2 significantly improved the thermal conductivity, thereby decreasing the ignition delay of B/PDB, and the ignition delay of B/PDB with AP. The combustion of B/PDB and AP was more intense, extending the combustion duration, forming volatile fluorine compounds, and increasing combustion reaction efficiency. In general, this energetic fluorinated-centred surface modification has potential applications to enhance the ignition and combustion characteristics in B.

Numerical Study of Hydrogen-Rich Fuel Coherent Jet in Blast Furnace Tuyere

Injecting hydrogen-rich fuel into blast furnaces is an effective strategy to reduce carbon dioxide (CO2) emissions. The present study established a three-dimensional (3D) model based on a coherent jet of hydrogen-rich fuel. The combustion characteristics and the flow, heat, and mass transfer behaviors in the reaction region were simulated by the Computational Fluid Dynamics (CFD) method. The effects of fuel jet velocity on the distributions of gas velocity, temperature, and species in the reaction region were systematically analyzed. The results show that hydrogen-rich fuel burned around the main jet, generating a high-temperature, low-density flame. As flame length increased, the main jet experienced less decay. The outward expansion of the jet caused continuous diffusion of gas temperature and its components. As the fuel jet velocity increased, the temperature along the main jet centerline rose sharply, while the length of the high-concentration gas region extended. Doubling the jet velocity increased its centerline velocity by 11% and raised the average reaction region temperature by 4.12%. The obtained highlighted results are of paramount importance for optimizing hydrogen-rich smelting in blast furnaces.

Effects of structural parameters of active pre-chamber on the combustion process of methanol/gasoline TJI rotary engine

The application of Turbulent Jet Ignition (TJI) combustion mode in spark ignition engine can improve combustion efficiency and output power. This paper innovatively proposes the application of active pre-chamber (APC) in rotary engine (RE) to realize this mode. And blending a certain percentage of methanol in gasoline to achieve carbon reduction. A three-dimensional computational model of the APC-RE was developed, and the effects of three APC structural parameters including throat section diameter, throat section length and orifice diameter on the component flow and combustion characteristics were investigated. The results showed that the APC-RE exhibited higher sensitivity to the diameter of the throat section than the length variation under the fixed active fuel injection strategy. The low length or small diameter of the throat section causes insufficient energy in the APC jet, and too high values cause unstable combustion. The optimal APC volume is achieved at a throat length of 8 mm and a diameter of 6 mm, with the highest Indicated mean effective pressure (IMEP) and Indicated thermal efficiency (ITE). Next, The APC volume was fixed and the effect of jet orifice size on RE performance was discussed and the optimal size was determined 1.25 mm, which can further optimize the jet velocity and can continue to increase IMEP and ITE by 1.24 % and 1.46 % respectively.

Experimental investigation on ammonia combustion ignited by methanol-enriched active pre-chamber in an optical engine

To enhance the ignitability and burning rate of ammonia-fueled spark ignition engines, it is an effective way to adopt active pre-chamber (PC) ignition with high-reactivity fuel. Therefore, in this paper, the ammonia combustion characteristics using methanol-enriched active PC ignition were investigated, based on optical engine experiments with simultaneous in-cylinder flame imaging and pressure measurement. Results show that the overall combustion process is characterized by a three-stage heat release: (I) jet flame controlled combustion; (II) ammonia flame propagation; (III) post jet induced combustion. In stage I, methanol active PC jets with high-momentum and high-reactivity are discharged to ignite MC ammonia mixture, contributing to the first peak of heat release rate. In stage II, ammonia turbulent flame propagation dominates the combustion. In stage III, post jets induce the third peak of heat release rate. In this way, with a minimal methanol energy ratio (ER) of lower than 10 %, stable and fast ammonia combustion is achieved under stoichiometric (λMC = 1) and lean-burn (λMC = 1.2) condition, with cyclic variation of indicated mean effective pressure (IMEP) lower than 5 %, flame probability higher than 80 % and maximum global flame speed of about 4 m/s. A highest IEMP of 0.72 MPa and a peak indicated thermal efficiency (ηit) of 30 % is obtained at λMC = 1 and λMC = 1.2, respectively. However, at the rich limit of λMC = 0.9 and lean limit of λMC = 1.4, the quenching of jet flames leads to weak ignition and unstable combustion, which is identified by reduced flame probability distribution and increased cyclic variation of IMEP. In addition, to ensure the cyclic combustion stability, there is also an operating range of methanol ER. At λMC = 1.2, unstable ignition and deteriorated combustion occur below the lower limit of ER = 6 % and above the upper limit of ER = 17 %. This paper can provide data support and operation strategy for the combustion improvements of ammonia-methanol active jet ignition engines.

Transforming wastewater-derived algae biodiesel with ammonium hydroxide emulsion for enhanced energy efficiency and emission reduction

The growing demand for sustainable energy has prompted a search for alternative fuels, with microalgae-based biodiesel emerging as a promising option. However, improving its energy efficiency and minimizing environmental impacts remain key challenges. This study presents a novel approach by integrating wastewater-derived algae cultivation with ammonium hydroxide emulsion to enhance biodiesel performance. Chlorella vulgaris microalgae were grown in a medium of diluted human urine, where nutrient removal efficiency was evaluated, and biooil was extracted via solvent extraction. The resulting biodiesel was analyzed for elemental, chemical, and physicochemical properties. A 30 % blend of Chlorella vulgaris algae biodiesel (CVAB) with normal diesel fuel (NDF) was prepared. To further boost energy efficiency and emissions performance, ammonium hydroxide emulsion was added at concentrations of 5 % and 10 %. Results confirmed that wastewater-sourced algae cultivation is a viable method for sustainable biodiesel production. While CVAB's combustion characteristics were similar to NDF's, it exhibited a 7 % decrease in brake thermal efficiency and a 5 % increase in nitrogen oxide emissions. The addition of ammonium hydroxide emulsion notably improved both energy efficiency and emission profiles. This study highlights a breakthrough in using ammonium hydroxide emulsion to enhance algae biodiesel, making it a more competitive alternative to fossil fuels. Economically, this approach offers a dual advantage: utilizing low-cost wastewater for biodiesel production while improving fuel performance and reducing emissions.

Effect of PTFE content on the laser-induced ignition and combustion characteristics of Al@PTFE composite fuels

This paper prepared aluminum@polytetrafluoroethylene (Al@PTFE) composite fuels with different PTFE contents and evaluated the effect of PTFE content on the thermal and combustion characteristics via multiple characterization methods. The scanning electron microscopy (SEM) and thermogravimetry–differential scanning calorimetry (TG-DSC) results showed that the PTFE was well coated on the surface, and the higher the PTFE content, the faster the oxidation reaction rate. Al@PTFE_8% fuel demonstrated more stable thermal performance and higher weight gain. Al@PTFE_15% had a weak endothermic peak at 337.2 °C, while the other two fuels did not appear. The nanosecond pulsed laser-induced plasma ignition (LIPI) test showed that compared to pure Al counterpart, Al@PTFE fuels could effectively shorten the ignition delay and promote the energy release, for Al@PTFE_8% with a reduction of 41.9% in ignition delay and an increase by 17.1 % in combustion temperature. The self-sustaining burn time decreased as the PTFE content increased. The gas-phase combustion of Al@PTFE fuels were more pronounced, and their AlO spectral signal intensity were stronger. The Al@PTFE combustion residues showed lots of cracks and holes, and the mass fraction of O was increased from 22.96 % (Al) to 30.53 % (Al@PTFE_8%). The proposed combustion mechanism reveals that PTFE destroyed the alumina film that hindered combustion, significantly promoting the combustion of Al particles. This study provides guidance for laser-induced plasma ignition of this material under ultrahigh heating rates.

Combustion Characteristics and Performance of Nanoflower Structure AlB2@AP Energetic Composites

ABSTRACT Boron-based solids have garnered significant attention due to their high calorific value. However, during combustion, the formation of boron oxide (B₂O₃) on the surface hinders the interaction between the oxidizing components and the internal active boron (B), thereby limiting its reactivity and combustion efficiency. Modifying boron-based solids represents an effective strategy for overcoming the limitations associated with fuel energy release efficiency. In this study, a shell-structured AlB₂@AP composite was designed and fabricated utilizing etching and recrystallization methods. The structure comprises AlB₂ as the core, B as the middle shell, and AP as the embedded outer shell. The key strategy involves employing an etching process to augment the reactive surface area of boron on the aluminum diboride surface, while also coating it with ammonium perchlorate (AP) to enhance the composite particles. This innovative approach demonstrates that the etching method can effectively utilize the boron present in AlB₂. The composite particles were characterized and analyzed for morphology employing a scanning electron microscope and X-ray techniques. Thermal analysis indicated that the decomposition stage of AP facilitated the oxidation of etched AlB₂, moreover, as the AP coating content increased, the temperature at which vigorous reactions initiated occurred earlier. In combustion experiments, the maximum combustion temperatures of AlB₂@10AP, AlB₂@20AP, and AlB₂@30AP increased by 36.4%, 15.1%, and 3.8%, respectively. The combustion formulation prepared with elemental boron exhibited different characteristics. The average combustion temperatures increased by 33.1%, 23.4%, and 14.4%, respectively. The combustion durations were reduced by 60.8%, 33.7%, and 31.7%, respectively. AlB2@AP is anticipated to further enhance its applications in propellants, explosives, and pyrotechnics.

Study on combustion characteristics of ammonium perchlorate enhanced hydroxylamine nitrate-based electronically controlled solid propellant

Electrically controlled solid propellants (ECSPs) have attracted significant attention as a novel class of solid propellants owing to their unique electrochemical properties. In this study, a series of ECSP formulations composed of hydroxylammonium nitrate (HAN), ammonium perchlorate (AP), and polyvinyl alcohol (PVA) were prepared and experimentally investigated to understand the effect of applied voltage on their combustion characteristics, and their combustion behavior was systematically characterized. The results demonstrated that the addition of AP decreased the initial conductivity of the ECSP; however, the average combustion rate during steady-state burning increased significantly, along with a corresponding increase in the combustion temperature. This effect became more pronounced with increasing AP concentration. The dissolved AP in the system acts as an efficient charge carrier, whereas the undissolved AP enhances the combustion performance by producing oxygen through thermal decomposition. Furthermore, even under atmospheric pressure conditions, the combustion of the ECSP can be effectively controlled by adjusting the applied voltage, with combustion ceasing upon removal of the voltage. The mechanism by which AP enhances combustion was analyzed, providing new insights for the optimization of ECSP formulations.