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Nanofluid fuel has garnered significant attention due to its potential to enhance combustion characteristics, energy density, and ignition properties. The study comprehensively examined the effects of aluminum nanoparticles with diverse sizes (50 nm, 100 nm, 200 nm, 500 nm, 1 μm) and concentrations (2.5 wt%, 5.0 wt%, 7.5 wt%) on the ignition and combustion characteristics of nanofluid fuel droplets, utilizing a mechanically mixed aluminum-based nanofluid fuel solution that incorporated kerosene, aluminum particles, and the surfactant oleic acid. The combustion process of the nanofluid fuel droplets encompasses phases of ignition, steady combustion, micro-explosion, and agglomerate reaction. The surface temperature of the nanofluid fuel droplets consistently exceeded that of a pure kerosene droplet, with temperature elevations correlating positively with particle concentration but not with the particle size. The surface temperature of nanofluid fuel droplets containing 7.5 wt% aluminum particles is approximately 205°C. The incorporation of oleic acid into pure kerosene prolongs the ignition delay from 0.317 s to 0.333 s. The combustion rate of the nanofluid fuel droplets escalates upon the addition of aluminum particles, with the rate escalating in tandem with the diameter and concentration of the aluminum particles. Nanofluid fuel droplets containing 5.0 wt% aluminum and 5.0 wt% oleic acid particles exhibit a combustion rate akin to that of pure kerosene droplets, with rates of 0.596 and 0.604 mm2 s−1, respectively. Concurrently, the ignition delay for nanofluid fuel droplets is longer than that of pure kerosene, yet it exhibits insensitivity to particle size. The ignition delay for nanofluid fuel droplets with the addition of 7.5 wt% aluminum particles is approximately 1.5 times that of kerosene. Nanofluid fuel droplets devoid of oleic acid yield divergent results due to particle agglomeration effects. Subsequently, as particle size increased, the surface of combustion residue develops more pronounced bulges, becoming more prone to rupture. Ultimately, a kinetic prediction model is proposed, accounting for the inhomogeneous properties within the droplet. The root mean squared errors for ignition delay time, combustion rate, and steady surface temperature are all below 8 %, indicating a strong correlation between model predictions and experimental data. This research could help accelerate the adoption of aluminum-based nanofluid fuel. • Droplet temperature rises with increasing particle content, regardless of size. • Rising particle size boosts droplet burn rate, without affecting ignition delay. • Larger Al particles make combustion residue surface bulge more, riskier to break. • A predictive model for stratified kerosene/OA/Al droplet combustion. [ABSTRACT FROM AUTHOR]

This paper describes the pulse injection of kerosene fuel in a kerosene-fueled supersonic combustor at a Mach number of 3. A high-flow mechanical pulsed injector was utilized to inject kerosene at frequencies ranging from 40 to 212 Hz in experiments. High-speed Schlieren images and wall pressure were employed to analyze the influences of various injection frequencies on the wave family and kerosene combustion performance. Initially, the pulsed injection causes intermittent changes in the wave family after kerosene ignition, leading to combustion instability. However, an optimal injection frequency of 143 Hz stabilizes the wave family. Additionally, pulsed injection reduces the kerosene ignition delay time, with the most notable reduction occurring at 113 Hz. Finally, the average combustion intensity of kerosene with pulse injection is lower than that of steady injection. However, the instantaneous combustion intensity at 143 Hz is similar to steady injection, which constitutes a significant portion of the overall combustion process. In summary, pulse injection of kerosene at 143 Hz could achieve efficient and stable combustion at a Mach number of 3. • Pulse injection of kerosene results in intermittent changes in the flow field. • An optimal injection frequency contributes to a continuous flow field. • Pulse injection can shorten the ignition delay time of kerosene. • An optimal injection frequency can enhance kerosene combustion efficiency. [ABSTRACT FROM AUTHOR]

This study describes the use of the emulsion liquid membrane (ELM) technique to recover thorium (Th(IV)) from an aqueous nitrate solution. The components of the ELM were kerosene as a diluent, sorbitan monooleate (span 80) as a surfactant, bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) as an extractant, and H2SO4 solution as a stripping reagent. Th(IV) was more successfully extracted and separated under the following favorable conditions: Cyanex272 concentration of 0.11 mol/L; 0.65 mol/L H2SO4 as a stripping phase (internal phase); feed phase (external phase) pH of 1; internal-to-membrane phase volume ratio of 1; emulsion-to-external phase volume ratio of 0.4; contact time of 25 min; and agitation speed of 300 rpm. Under these conditions, the membrane transferred Th(IV) selectively from the real leach liquor without appreciable emulsion breakage or swelling. [ABSTRACT FROM AUTHOR]

Obtaining quantitative experimental data on soot properties of aviation kerosene at elevated pressures is a significant concern for the surrogate fuel kinetic model of aviation kerosene. However, there are scarce studies on soot formation and properties of aviation kerosene in tractable flames at elevated pressures in literature. In this study, Chinese RP-3 aviation kerosene is used in relevant experiments and numerical simulations up to 3.5 atm to evaluate the effect of pressure on soot formation and properties. Soot morphology, nanostructure, and concentration are studied by transmission electron microscopy and laser extinction method. Then, an RP-3/PAH kinetic model containing the 5-aromatic rings (A5) growth mechanism is proposed to simulate the soot formation processes at elevated pressures. Quantitative experimental results show that pressure significantly affects the soot morphology, nanostructure parameters. The peak soot volume fractions in the RP-3 flame scale with the pressure as ${P^{1.62}}$ P 1.62 . The numerical results show that the RP-3/PAH model can depict the trends of soot particle size and soot volume fraction with pressure. At 1.0–3.5 atm, the rates of soot growth processes increase with pressure, especially the PAHs condensation. The significantly increased soot surface growth rate may be one of the main factors for the variation of soot properties with pressure. The quantitative experimental and numerical results contribute to the understanding of the kinetic mechanism of soot formation for RP-3 kerosene at elevated pressures. [ABSTRACT FROM AUTHOR]

This study investigates the impact of reinforcing weak subgrade clay soil (WSCS) from the Koye Feche road project in Addis Ababa, Ethiopia, using natural fiber (katcha), kerosene, and sand. Various combinations of katcha fiber content (0.5%, 1%, and 1.5%), kerosene‐soaked katcha fiber lengths (20, 35, and 50 mm), and sand percentages (10%, 15%, and 20%) were tested to determine their effects on the soil's performance. Unconfined compressive strength (UCS) and California Bearing Ratio (CBR) tests were conducted to identify the optimum mix. Results indicate that the maximum UCS value is achieved with 1% katcha fiber content, 35 mm katcha fiber length, and 20% sand content. The plasticity of the optimum mix decreases to 31.46%, while its strength increases to 59.75% compared to the untreated subgrade clay soil. The reinforced soil demonstrates durability comparable to conventional materials, with a cost‐saving of 40.71% over traditional replacement methods. This suggests the viability of reinforced soil in pavement construction, offering enhanced performance and economic benefits. [ABSTRACT FROM AUTHOR]

This novel research presents an investigation on petroleum products dehydration using the adsorption method by low-cost adsorbents. To investigate the performance of proposed process intended to separate emulsified water, synthetic stabilized water emulsions in different petroleum products (Gasoline, Kerosene, and Gas oil) which equal 300, 600, and 800 ppm were prepared. Afterwards, under batch conditions, natural zeolite and activated carbon as economic adsorbents were utilized for the dehydration process. The characteristics of adsorbent was examined using SEM and XRD analysis. The obtained results from BET analysis also depicted that the specific surface area of activated carbon was considerably more than that of zeolite. Results showed that both zeolites and activated carbon can effectively purify petroleum products from undesirable emulsified water. The comparison of the adsorbents' efficiency indicated that activated carbon has a higher affinity than zeolite for water in gasoline and gas oil, however, they had almost the same adsorption capacity in kerosene dehydration. The maximum water removal percentage of gas oil, kerosene and gasoline using zeolite was 84.84, 92.17, and 88.64, respectively. Dehydration by activated carbon also led to 86.44, 93.43 and 90.2 per cent water removal from gas oil, kerosene and gasoline, respectively. [ABSTRACT FROM AUTHOR]

Staged combustion technology is widely applied in modern low-emission energy and power systems. This study employs large eddy simulations (LES) to investigate the flame dynamics and emission characteristics in a staged two-phase partially premixed model combustor. To improve the suitability of the thickened flame model (TFM) for turbulent flames in the thin-reaction-zone regime, a new model for efficiency function is formulated such that the effects of small-scale turbulence on flame propagation are taken into account. The enhanced LES-TFM approach is then integrated with an efficient NOx model, in which an additional NOx transport equation is solved with pre-tabulated NOx formation source terms. Five LES runs are performed to investigate the evolution of flame dynamics and emission characteristics with staging ratios at the scaled cruise operating conditions, in which the optimal staging ratio is critical for NOx reduction. Results show that the trend of flame morphology and NOx emission predictions with staging ratios are consistent with the experimental results. The flame zones in the staged model combustor shift from a pilot-stage-only flame to a pilot-primary-stage flame, then to a primary-stage-only flame with decreasing fuel staging ratio. Due to the redistribution of the equivalence ratio and the NOx emission characteristics trade-off between the two-stage flows, there is an optimal staging ratio for NOx reduction in the staged model combustor. The proposed LES-TFM-NOx approach, which has both the benefits of efficient flame dynamics modeling with the global reaction mechanism and the advantages of prediction accuracy with the detailed mechanism for NOx emission, demonstrates its advantages in simulating flame and emission characteristics in low-emission combustion devices. [ABSTRACT FROM AUTHOR]

Kerosene/hydrogen-peroxide (H2O2) green propellant system has relatively high operational ratio of oxidizer (O) to fuel (F) that complicates the injector design and its layout. In this research, a procedure of two-stage, like-doublet (O-F-F-O) impinging-jet injector design is presented, where mixing of H2O2 and kerosene occurs between O-O and F-F sprays. Investigations at O/F ratios between 3.75 and 6.25 are performed. The impinging distance, angle, and jet velocity of the two-stage impinging-jet module are the design parameters examined. The PLIF technique is used to observe the spatial droplet distribution of the individual spray. The predicted mixing behavior by overlapping the individual fuel and oxidizer sprays is compared to the actual mixing of the O-F-F-O spray to justify the spray/spray interactions. Detailed behaviors of the fuel and oxidizer sprays are revealed. The effects of O/F ratio and other design parameters on the injector flow dynamics and propellant mixing are examined systematically. With experimentally defined shape factors, an optimum design of the injector element can be determined for a given injector plate. The design of the injector plate for a 450 N thrust engine is demonstrated, and the design is justified by the hot-fire test of the engine. [ABSTRACT FROM AUTHOR]

The research objective of this paper is to obtain an efficient space engine chamber wall adherent kerosene blow-off solution, the research methodology uses computational fluid dynamics method and experiments are conducted to verify the numerical calculation accuracy. The effect of gas pressure, gas temperature, ambient temperature, and gas type on the blow-off efficiency was obtained, in which increasing the pressure and temperature of the blow-off gas increased the treatment efficiency by 14.16% and 9.85%, respectively, and the blow-off efficiency was significantly improved. Increasing the operating ambient temperature and changing the type of purge gas increased the treatment efficiency by 4.76% and 5.88%, respectively. Finally, the removal scheme was optimized by increasing the blow-off gas pressure and temperature, and the treatment efficiency of the optimized scheme was improved by 37.5% compared to the original scheme. The findings of this paper provide important guidance for the efficient blow-off off of kerosene adhering to the inner wall of complex structural cavities. [ABSTRACT FROM AUTHOR]

In advanced aeroengines with higher inlet temperature, the cooling capacity of kerosene should be fully used, which turns kerosene into supercritical. The spray features of supercritical kerosene make the mixing process of supercritical kerosene with air different from that of subcritical kerosene. In this work, the spray of supercritical kerosene in a swirling flow field is investigated experimentally. The spray characteristics of supercritical kerosene are obtained using the schlieren technique. The instability of the jet morphology is analyzed using proper orthogonal decomposition (POD) method. The results prove that the combustor head structure significantly affects the overall spray morphology. A "packet structure" caused by density stratification is observed in the spray, which suppresses the circumferential diffusion of the jet. The "packet structure" is highly correlated with the airflow speed. The structural parameters of the supercritical kerosene jet are not sensitive to the changes in kerosene injection pressure, which, however, has a positive correlation with injection temperature. The main cause of the instability of the jet morphology in supercritical kerosene jets is the formation and shedding of vortices on the jet surface, which can be intensified by condensation. Density stratification suppresses shear layer instability, stabilizing the "packet structure" during the injection. [ABSTRACT FROM AUTHOR]

An experimental study was conducted to investigate the behavior of an H 2 O 2 /kerosene bipropellant thruster during throttling. The thruster used 90 wt% hydrogen peroxide, and thrust was controlled using a variable area cavitating venturi valve equipped with a linear motor translating a pintle in a venturi geometry. In particular, transient effects were compared for three settings of pintle motion. Transient effects impacting pressure, temperature, thrust, efficiency, and instability data were analyzed. The results show that even at low chamber pressure, ignition occurred due to throttling, and no instabilities were created by changing the throttling speed. On the contrary, transient movements affected the recorded pressure data, impacting the characteristic velocity and thrust. Finally, this study provided new insight into H 2 O 2 /kerosene bipropellant throttling for deep throttling missions. Moreover, using the results from this study, the precision of future control algorithms will be improved. • Investigated H 2 O 2 /kerosene thruster dynamics during throttling. • Investigated transient effects by varying the pintle motion in oxidizer line. • Performed a 10.4:1 throttling range in bipropellant configuration. • Ignition was maintained during throttling at low pressure. [ABSTRACT FROM AUTHOR]

In recent years, researchers are looking for ways to reduce the amount of sulfur in kerosene. Therefore, desulfurization of kerosene is considered an important commercial and environmental process. Among the hard and complicated methods available for the desulfurization process, natural zeolites can be a suitable alternative for the desulfurization of oil products due to their economic efficiency, biocompatibility, and natural abundance of oil reserves. In this research, natural zeolite (clinoptilolite) was modified with CuO nanoparticles and used as adsorbent for desulfurization of kerosene. The effect of important parameters such as adsorbent dose, pH of solution and initial adsorbate concentration were investigated. Results indicated the optimum conditions as follows: dose of adsorbent 2 g, pH 10 and the adsorbate dose 200 ppm. Results showed that the modified adsorbent is a suitable, low-cost and good efficiency for the desulfurization process of kerosene. [ABSTRACT FROM AUTHOR]

The ethylene tar and mixtures of ethylene tar with other petrochemical by-products were used as collectors for coal flotation. The results showed that the 1# compound collector was better than kerosene in terms of selectivity and collectibility for coal flotation. When the collector dosage was 1500 g/t, the yield of clean coal using the 1# compound collector increased by 4.05%, and the reduction in ash content was 0.36% lower compared to using kerosene. The mechanism of action of 1# compound collector on the coal surface was analyzed in combination with GC-MS tests and FTIR tests. The 1# compound collector contains more aromatics, olefins and heteropolar substances than kerosene. When the aromatics in the 1# compound collector interact with the nonpolar sites on the coal surface via π–π stacking interactions, some of the polar sites sandwiched between the aromatic compound molecules are covered. The olefins contained therein engage with the nonpolar sites on the surface experiences interactions attributable to van der Waals forces. The oxygenated functional groups of alcohols, acids, esters and carbonyl compounds engage with the polar sites on the surface of the particles through hydrogen bonding. [ABSTRACT FROM AUTHOR]

In order to determine the optimal wall pressure location as the controlled parameter for kerosene-fueled scramjet, a combined approach of numerical simulation and experimental analysis was employed. The results indicate that with an increase in the equivalence ratio of kerosene, the combustor exhibits consecutive modes, including pure scramjet mode, dual-mode scramjet mode, dual-mode ramjet mode, and pressure disturbance to the isolator inlet mode. The peak pressure ratios corresponding to the mode transition boundaries are 1.95, 3.26, and 3.57, with respective isolator outlet Mach numbers of 1.62, 1.0, and 0.74. The equivalence ratio corresponding to mode transition increases with an increase in the combustor inlet total temperature. Considering the dynamic characteristics of wall pressures at different locations, the position at x/L = 0.46 demonstrates the best linearity, highest sensitivity, and greater stability. Hence, it is the most suitable choice as the controlled parameter for fuel flow in this kerosene-fueled scramjet. [ABSTRACT FROM AUTHOR]

The research experimentally examines the viability of ethanol (E) as a sustainable aviation fuel (SAF) when mixed with kerosene (Ke) – Jet A aviation fuel + 5% Aeroshell oil. Various blends of ethanol and kerosene (10%, 20%, and 30% vol. of ethanol added in kerosene) were subjected to testing in an aviation micro turbo-engine under different operational states: idle, cruise, and maximum power. During the tests, monitoring of engine parameters such as burning temperature, fuel consumption, and thrust force was conducted. The study also encompassed the calculation of crucial performance indicators like burning efficiency, thermal efficiency, and specific consumption for all fuel blends under maximum power conditions. Physical-chemical properties of the blends, encompassing density, viscosity, flash point, and calorific power, were determined. Furthermore, elemental analysis and FTIR were used for chemical composition determination. The research delved into analyzing the air requirements for stoichiometric combustion and computed resulting emissions of CO2 and H2O. Experimental assessments were performed on the Jet Cat P80® micro-turbo engine, covering aspects such as starting procedures, acceleration, deceleration, and emissions of pollutants (CO and SO2) during diverse engine operational phases. The outcomes reveal that the examined fuel blends exhibited stable engine performance across all tested conditions. This indicates that these blends hold promise as sustainable aviation fuels for micro turbo-engines, presenting benefits in terms of diminished pollution and a more ecologically sound raw material base for fuel production. [ABSTRACT FROM AUTHOR]

This work aimed to investigate the removal of sulfur compounds from light kerosene using activated carbon (AC) that was treated with alkali agents (KOH and NaOH) to enhance its adsorption properties. The physicochemical properties of the as-received AC and AC/alkali agents were characterized using Fourier transform infrared spectroscopy (FTIR). To evaluate the effectiveness of the surface modifications on the adsorbents, various operating conditions were examined. The agitation speed varied between 200, 300, and 400 rpm, while the contact time ranged from 15 to 35 minutes. Additionally, different percentages of KOH (5, 10, 15%) and NaOH (5, 10, 15%) were used to assess their influence on the removal efficiency of sulfur compounds. Based on the given information, it appears that the treatment of activated carbon (AC) with alkali agents, specifically KOH and NaOH, has resulted in an increase in the specific surface areas of the AC. This increase in surface area could potentially enhance the adsorption capabilities of the AC. The results showed that AC/KOH achieved a sulfur removal efficiency of 69%, while AC/NaOH demonstrated a higher efficiency of 84%. The highest sulfur removal efficiency was achieved under specific conditions: a NaOH concentration of 4 M, agitation speed of 400 rpm, and contact time of 35 minutes. Overall, the treatment of activated carbon with alkali agents, particularly NaOH, led to increased specific surface areas and the presence of hydroxyl functional groups. The surface area of AC-treatment will be increased because the functional group formation new location in AC-support and increased the porosity, therefore the surface area will increase. The resulting composites, AC/KOH and AC/NaOH, demonstrated enhanced sulfur removal efficiency compared to other composites, with AC/NaOH showing the highest performance. [ABSTRACT FROM AUTHOR]

Transport properties of hydrocarbon liquid-based nanofluids in non-Darcy media have key significance in chemical, thermal and mechanical engineering. Therefore, the key focus of this research is to investigate the transport mechanism in nanofluid using Koo–Kleinstreuer–Li (KKL) thermal conductivity model in non-Darcy media under squeezing and permeable effects. The functional fluid is a homogenous mixture of Cu and kerosene. The problem formation is carried out via nanofluid-enhanced properties and similarity rules. Then numerical scheme was endorsed for the results analysis under increasing physical ranges. It is observed that the velocity F(η) increased when the values of α1 vary from 1.0 to 4.0. However, quick particles movement is noticed for γ1 for 1.0–4.0 and −1.0 to −4.0. Further, the thermal process in Cu/kerosene depreciates for α1=0.5, 1.0, 1.5, 2.0, γ1=2, 4, 6, 8 and γ1=−2.0, −4.0, −6.0, −8.0, respectively. The stronger permeability of the lower plate highly reduced the fluid movement and depreciation in the movement can be optimized when the fluid sucks from the channel through the lower plate. [ABSTRACT FROM AUTHOR]

Crude oil distillation (CDU) is a crucial unit in refinery plants for producing various crude oil cuts, such as naphtha, kerosene, light gas oil, heavy gas oil, and Atm residue. This study used ASPEN HYSYS V11 software to examine the parameters that affect CDU efficiency in South Refinery Company /Iraq-Mishriff crude oil, like temperature, pressure, and flow rate. Optimization of these variables was applied to identify suitable values for separation products. The study reveals that the increased mass flow rate of crude oil to CDU increases the flow rates of naphtha, kerosene, and HGO. The study also examines the impact of the temperature of feed crude oil on CDU. Results show that the volume flow of products increases with increased temperature except the naphtha values decrease. The simulated liquid volume flow for the Naphtha value was 57.96 m³/h higher than the original data of 50.7 m³/h and the kerosene value was 49.24 m³/h lower than the plant value of 51.5 m³/h. The effect temperature was also studied, the volume of liquid flow is directly proportional to the increase in temperature of the crude oil, whether it was a TBP or ASTM blend. The refinery and simulated values were compared, and a satisfactory agreement between the simulated and real results was observed, with some clear differences in the LGO values. The cause of this difference may be the result of the changes during the laboratory tests, or Sampling strategies may affect the accuracy of ASTM D86 tests and laboratory results. Optimization is crucial for optimal operating conditions for efficient product production. Most plant data align with optimized conditions, except for some. For instance, the perfect temperature of crude oil in the distillation unit is 382 °C instead of 375 °C, and the better mass flow of LGO steam is 1431 kg/h rather than 1100 kg/h. [ABSTRACT FROM AUTHOR]

A W/O microemulsion of AM/H2O Span80/Tween80 kerosene system was prepared with acrylamide (AM) monomer aqueous solution as dispersion phase, Span80/Tween80 as emulsifier and kerosene as dispersion medium. The crosslinked polyacrylamide microspheres with nanometer size were prepared by inverse microemulsion polymerization at 70°C. The microscopic analysis shows that the internal structure of the microsphere is broken during oil displacement, the water cut decreases and the oil recovery increases. When the amount of crosslinking agent is 1.3%, the microsphere flooding effect is good. After the microsphere is injected, the water content of the high permeability pipe decreases by 29.4%, and the oil recovery of the low permeability pipe increases by 33.8%, indicating that the microsphere has a good effect of precipitation and oil increase. The injection pressure was low at the initial stage and then rose to nearly 100 kPa, indicating good injectivity of the microspheres. [ABSTRACT FROM AUTHOR]

This paper presents the results of experiments conducted on the flotation separation of cyclone dust particles. The flotation process was conducted using a laboratory flotation apparatus comprising three chambers. Experimental tests supported theoretical results of the theoretical reasoning and justification for the choice of parameters that the flotation process should have in order to extract particles of such small sizes. Furthermore, this work elucidates the concept of "nanobubbles" and substantiates their viability for use in the flotation of nanoparticles, given that bubbles of such a magnitude are firmly affixed to the hydrophobic surface of particles. Bubbles of a larger size than nanoparticles will float both hydrophobic and hydrophilic particles. The effective flotation of cyclone dust from the gas cleaning of silicon and ferroalloy production provided two materials as a result. The experiments yielded insights into the rational technological parameters of the flotation mode for obtaining new products. These insights were gleaned from the preliminary conditioning (conditioning time from 0.5 to 1.5 h) of wet cyclone dust (dry dust weight of 4 kg) with liquid glass (1.4 g per 1 dm3 of pulp) in a cavitation unit at a pH value of 8.5. The flotation process was conducted in a three-chamber flotation apparatus with a volume of 0.02 m3 for a duration of 90 min, utilizing a pneumohydraulic aerator with air suction from the atmosphere. In this instance, the pulp was conveyed via a pump at a pressure of 0.4 MPa from the initial cleansing chamber into the aerator. During the flotation process, kerosene (1 mg per 1 dm3 of pulp) and pine oil (2 mg per 1 dm3 of pulp) were added as additives. The resulting products were silicon dioxide (95%) and carbon nanoparticles (94%). [ABSTRACT FROM AUTHOR]

This paper examines the safety of aero-engine pipelines under different heating conditions. Based on the fire test standard documents, a model of an aero-engine oil pipe was constructed, and its safety under heating conditions that meet the standard was analyzed using fluid–solid thermal coupling. The pipe material was stainless steel 1Cr18Ni9Ti, and the oil inside the pipeline was China RP-3 kerosene. To simulate the different working conditions or pump failure scenarios, various kerosene inlet flow rates were used for the calculations. The results indicate that the pipe wall exhibits an uneven temperature distribution under standard heating conditions. As the kerosene flow rate decreases, the pipe wall temperature rises, and heat transfer deterioration occurs. The increase in the pipe wall temperature reduces the material's strength, while the uneven temperature distribution generates thermal stress, further increasing the safety risk. When the kerosene flow rate is reduced to a certain level, the equivalent stress in the pipe wall exceeds the material's yield strength, leading to a high risk of rupture. [ABSTRACT FROM AUTHOR]

As the main energy consumption of aviation and aerospace, the study of combustion characteristics of aviation kerosene is of great significance. In this paper, through the self-built experimental system, the combustion flame characteristics of pure aviation kerosene, aviation kerosene mixed with n-amyl alcohol, aviation kerosene mixed with dimethylfuran were studied under different working conditions, and the physicochemical properties of soot particles generated in the flame, and the effects of mixing n-amyl alcohol and dimethylfuran on the formation of soot particles were analyzed from the microscopic perspective. The results show that: 1. The soot particles in the combustion of aviation kerosene mixed with n-amyl alcohol and dimethylfuran show some characteristics of amorphous structure, unclear outline and incomplete curing; 2. Under K-D20 condition, nitrates are included in particulate matter generated by soot; 3. After mixing n-amyl alcohol and dimethylfuran, the degree of graphitization continues to decrease. [ABSTRACT FROM AUTHOR]

Copper molybdenum mixed concentrate usually uses the process of full flotation to separate copper and molybdenum minerals, which has the characteristics of high separation difficulty and high consumption of sodium sulfide. In order to optimize the copper molybdenum separation and beneficiation process, the difference in the specific magnetization coefficient of copper and molybdenum minerals is utilized to systematically conduct experimental comparative study between the "magnetic separation-flotation, combined process and full flotation, in order to improve the copper molybdenum separation indicators. Julong molybdenum bearing copper concentrate in Tibet contains 20.49% copper and 0.68% molybdenum. The main copper mineral is chalcopyrite, followed by bornite and chalcocite, and the main molybdenum mineral is molybdenke. Through the experimental study of the, magnetic separation-flotation, combined process, the molybdenum containing copper concentrate was ground to a content of -0.038 mm accounting for 60%, and the high magnetic separation concentrate with a of 35.48%, copper content of 26.48% and a molybdenum content of 0.08% was obtained. The magnetic separation tailings used "sodium hydrosulfide] BK510" as a copper mineral inhibitor and "kerosene+ BK345" as a collector. Flotation can obtain molybdenum concentrate with a molybdenum content of 52.37%, copper content of 1.58%, molybdenum recovery rate of 87.63% and copper recovery rate of 0.09% . The comprehensive copper concentrate contains copper of 20.71% and molybdenum of 0.09%. The copper recovery rate is 99.91% and the molybdenum recovery rate is 12.37%. Compared with traditional full flotation processed it can increase the grade of molybdenum concentrate by 2. 31 percentage points and the molybdenum recovery rate by 0.43 percentage points. Magnetic separation can pre-select copper concentrate with a yield of 35.48%, which can significantly reduce the amount of sodium sulfide. Simultaneously optimizing flotation reagents, using copper inhibitor BK510 in conjunction with the use of sodium hydrosulfide, and the combination of BK345 and kerosene, can improve the efficiency of copper molybdenum mineral separation and further reduce the amount of sodium sulfide. The research on the new process and reagents of "magnetic separation-flotation" for copper containing copper concentrate can provide technical support for the development of copper molybdenum ore. [ABSTRACT FROM AUTHOR]

The paper presents the results of simulation of spray and combustion processes in the liquid-propellant rocket engine chamber using the z77 reduced kinetic mechanism of chemical reactions and a hybrid method for determining spray parameters of a swirl atomizer. Simulation was carried out for the nominal operational conditions in a three-dimensional domain using the ANSYS Fluent software. The process of spraing liquid fuel components (T-1 kerosene and oxygen) by monopropellant injectors was simulated using a model of discontinuous phases. The simulation results (pressure, temperature and velocity) were compared with the data of analytical thermogasdynamic calculation results and experimental results for pressure in chamber and gas temperature near the wall. The difference between the simulation results and the experimental results does not exceed 8%. Thus, it was shown that it is possible to use the mechanism z77 and hybrid method for determining spray parameters of a swirl atomizer presented in this paper to obtain accurate simulation results of the kerosene T-1 and oxygen spray and combustion processes of the investigated liquid-propellant rocket engine.

Given the low plugging success rate of existing plugging agents in oilfield applications, this study proposed a new selective plugging agent system (SA-1-S) with a high plugging efficiency, which dissolves in oil and releases oil flow channels under formation temperature conditions. Being insoluble in water and acid, it blocks water flow channels. In particular, at ambient temperature of 25 °C and reservoir temperature of 65 °C, the dissolution rate of SA-1-S particles in formation crude oil, kerosene, and diesel oil exceeded 96%, being suitable for formations at temperatures below 120 °C∼130 °C. The proposed agent's plugging rate exceeded 90% on cores and 80% under reverse kerosene action; this rate dropped under forward scouring by 2.01 ∼ 3.21%. The selective water plugging agent proposed in this paper has application prospects in improving the oil recovery in high water-bearing oil wells. [ABSTRACT FROM AUTHOR]

The utilization of liquid fuel will greatly expand the application scope of rotating detonation engines, and there are still great challenges to achieve high-performance liquid-fuel rotating detonation operation. In this paper, aviation kerosene was used as the liquid fuel to investigate the effects of fuel temperature on the propagation characteristics of rotating detonation waves in two combustor structures: annular and cavity. An electric heating tape was employed to heat the kerosene up to 390 K. The results demonstrate that increasing the temperature of kerosene enhances its atomization efficiency, leading to a marked enhancement in the peak pressure and propagation stability of detonation waves. Moreover, the duration required to establish a detonation wave is notably reduced, as low as 11.2 ms. Furthermore, the detonation wave velocity increases with fuel temperature, with significantly higher velocities observed in the cavity combustor structure compared to the annular combustor structure. In the cavity combustor, the detonation wave velocity can reach up to 74 % of the theoretical CJ value. The results verify the feasibility of improving the rotating-detonation performance via increasing liquid-fuel temperature, which can provide reference for the engineering application of rotating detonation. • Experiments and numerical simulations on liquid fuel RDW were well conducted. • Atomization characteristics of liquid fuel under two combustors were analyzed. • RDW propagation characteristics with changing liquid temperature were obtained. [ABSTRACT FROM AUTHOR]

The numerical and experimental research of rotating detonation engines is usually conducted in ground environmental conditions. Although many breakthroughs have been made, there are still deficiencies in understanding engines operating in real flight conditions. In order to reveal the effect of engine size and initial kerosene droplet size on the rotating detonation engines in flight conditions, the Eulerian-Lagrangian model is adopted, and a series of two-phase kerosene/air rotating detonation cases are simulated in the conditions of Mach 5 and 24 km altitude. When 5 μm and 10 μm droplets are adopted, the RDE behaves like gaseous rotating detonations with clear cellular structures. When the 20 μm and 30 μm droplets are adopted, the rotating detonation waves tend to be divided into two layers and form the λ-shaped shock structure. The results indicate that droplet size and engine size influence detonation wave propagation and flow field mainly through droplet heat absorption and evaporation height. Increasing the engine sizes can promote the two-phase rotating detonation and broaden the initial diameter range capable of obtaining rotating detonation waves. However, as droplet size increases, the fresh mixture layer becomes stratified, with an upper layer predominantly comprising fuel vapor and a lower layer of fuel droplets, which results in an λ-shaped shock structure at the detonation front. The flight operation condition brings in differences in features such as detonation wave height and velocity deficit. The detonation height in flight conditions is higher than that in ground conditions. The most velocity deficit in flight conditions observed in our study is below 15 %, which is lower than the results (22.5 %) in ground operating conditions. These results indicate that the optimal design of the rotating detonation engine must consider the real operation conditions and the effect of engine sizes and droplet sizes. • The propagation characteristics of two-phase rotating detonation waves in flight operation conditions are revealed. • The effects of engine sizes and droplet sizes are analyzed. • Detonation height and propagation velocity are increased in flight operation conditions, compared with the ground test. • The rotating detonation engine design should be based on the real operation conditions. [ABSTRACT FROM AUTHOR]

Solvent extraction of selenium(IV) ions from highly concentrated hydrochloric acid using 0.4 mol/L Aliquat 336 dissolved in kerosene was investigated. As a modifying agent, 1-octanol (10% v/v) was added to the organic phase to avoid the third phase formation. The effect of different parameters affecting the liquid-liquid extraction of selenium(IV) such as the acid concentration, shaking time, metal ion concentration in the aqueous phase, loading capacity, diluents, and temperature, was studied. The results indicate that selenium(IV) is extracted efficiently by 0.4 mol/L Aliquat 336 dissolved in kerosene. It was noticed that the extraction increased with the increase in the acid and Aliquat 336 concentrations, reaching an extraction percentage of about 92% at 8 mol/L HCl and 97.1% at 1 mol/L extractant. The extracted organic species is postulated to be [H2SeO2Cl2.2R4NCl]org by using the slope analysis method, and the value of Kex for selenium(IV) extraction was found to be 26.17 ± 2 M− 2. The structure of the extracted organic species was confirmed by FT-IR. The effect of diluents using various aliphatic and aromatic diluents indicated that kerosene is the most preferred diluent. This is owing to safety ground purpose, economic consideration, the lower cost, availability, and lower toxicity. Thermodynamic parameters indicate the endothermic nature for the solvent extraction of selenium(IV) for the investigated system according to the positive value obtained of the enthalpy change (ΔH). Depending on the obtained results, the method was used to recover selenium(IV) from a simulated solution synthesized in hydrochloric acid medium, which is expected in anode slime leach liquor solution. [ABSTRACT FROM AUTHOR]

Coal gasification coarse slag (CGCS) has become a bulk coal-based solid waste that threatens the ecological environment. The high moisture content of carbon-rich coal coarse gasification slag (CR-CGCS) seriously limits its utilization. In this study, a pore water releasing method was proposed to promote the dewatering of CR-CGCS through size reduction with surface modification. Hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and kerosene were added during the grinding process, respectively. The results showed that kerosene can significantly improve the dewatering efficiency of CR-CGCS more than CTAB and SDS. The final moisture content of the CR-CGCS could be reduced from 47.50% to 33.01%. The SEM and FTIR results illustrated that kerosene could effectively reduce the content of oxygen-containing functional groups on the surface of CR-CGCS more than CTAB and SDS. Meanwhile, the PVM results showed that CR-CGCS modified by kerosene tended to form hydrophobic agglomerates. The LF-NMR results indicated that only the water in the macropores of CR-CGCS could be released in grinding process, but the water in micropores could be reduced when kerosene, CTAB, or SDS was added in grinding. This study provides new insight into enhancing the dewatering of CR-CGCS and theoretical support for the efficient utilization of CR-CGCS. [ABSTRACT FROM AUTHOR]

In this study, the differences in the combustion process of ammonia-premixed ignition with conventional diesel and kerosene as pilot fuels were investigated based on flame chemiluminescence, and further study on the effects of ammonia ratio (AMR) and direct injection timing (DIT) on the ammonia-kerosene dual-fuel combustion (AKDC) process was carried out. The results show that the kerosene with stronger volatility is more conducive to promoting rapid and stable combustion of ammonia. A composite flame structure is observed in dual-fuel modes. With the increase of AMR, the capacity to ignite ammonia is lessened, the flame area and luminosity are stabilized and then reduced, and the flame hue is transformed from blue-green to yellow. Higher combustion rates are observed when the DIT lies between −9° and −12° CA ATDC, resulting in higher flame area and luminosity. The overly advanced or delayed DIT leads to the deterioration of ammonia combustion. • An optical study of the AKDC and ADDC mode was conducted. • A composite flame structure is observed in AKDC and ADDC modes. • Kerosene is more conducive to the ignition of ammonia than diesel. • As AKDC phases are roughly the same, the combustion state of pilot fuel dominates. • Adjusting the phase of AKDC towards TDC via DIT helps the rapid combustion of it. [ABSTRACT FROM AUTHOR]

Of the processes that are approved to produce synthetic kerosene for use in jet fuel, about half produce olefinic kerosene that is hydrotreated. The alkene concentration in synthetic kerosene is indirectly regulated through the thermal oxidative stability specification. Perceptions about the deleterious influence of alkenes on thermal oxidative stability suggest that olefinic kerosene must be deeply hydrogenated. The extent of olefin saturation required has economic implications. To evaluate what an acceptable alkene concentration in synthetic kerosene is, the impact of alkene concentration on the outcome of the jet fuel thermal oxidative stability test (JFTOT) performed at 325°C in accordance with the ASTM D3241 standard test method was experimentally evaluated. Model synthetic kerosene mixtures to which different concentrations of alkenes (1‐decene, α‐methylstyrene, indene) were added, as well as control samples were studied. In the concentration range investigated, up to 10 wt% 1‐decene, 5 wt% α‐methylstyrene, and 2 wt% indene did not lead to increased fouling in the JFTOT. Fouling passed through a minimum value with increasing alkene concentration and alkene concentration on its own was a poor predictor of thermal oxidative stability. Analysis of the kerosene collected after passing through the JFTOT found measurable changes in density and refractive index. Dissolved oxygen reacting during thermal oxidative stability testing was accounted for mostly in oxygen‐containing products in the kerosene boiling range, which indicated that the heavier products were mainly hydrocarbon in nature. In addition to initiation by autoxidation, the investigation also pointed to the existence of a second thermally initiated fouling pathway that does not require the presence of oxygen. [ABSTRACT FROM AUTHOR]

In order to study the effect of coal-based kerosene on physical and chemical properties of jet fuel, the coal-based kerosene has been added to jet fuel, and the more than 20 kinds of physical and chemical properties of jet fuel have been tested according to national standard«No.3 jet fuel» (GB 6537). The results show that the physical and chemical properties of jet fuel containing coal-based kerosene meet the requirements of national standard «No. 3 jet fuel» (GB 6537). When the volume content of coal-based kerosene increases, 11 kinds of properties of the jet fuel behave monotonic variation, 13 kinds of properties keep unchanged. It can be seen that jet fuel containing coal-based kerosene still meets the requirements of national standard «No. 3 jet fuel» (GB 6537), whereas the coal-based kerosene has different influence on properties of jet fuel. [ABSTRACT FROM AUTHOR]

This study investigates the performance and environmental impact of n-butanol blended with Jet-A fuel in turbo engines, aiming to assess its viability as a sustainable aviation fuel (SAF). The research involves the experimental testing of various blends, ranging from low to high concentrations of n-butanol, to determine their effects on engine performance and emissions. The experimental setup includes comprehensive measurements of engine parameters such as thrust, fuel consumption rates, and exhaust gas temperatures. Emissions of sulfur dioxide (SO2), and carbon monoxide (CO) are also analyzed to evaluate environmental impacts. Key findings indicate that n-butanol/Jet-A blends can significantly enhance combustion efficiency and reduce emissions compared to conventional Jet-A fuel. Higher n-butanol concentrations lead to improved thermal efficiency and lower SO2 and CO emissions. This study underscores the potential of n-butanol as an SAF for turbo engines, highlighting its ability to mitigate environmental impacts while maintaining or improving engine performance. This research supports the feasibility of integrating n-butanol into Jet-A blends for turbo engine applications, emphasizing their role in achieving more environmentally friendly aviation operations. [ABSTRACT FROM AUTHOR]

This study experimentally investigates the challenges and solutions related to the development of local flame into global flame during kerosene spark ignition in a scramjet combustor operating at Mach 4 flight conditions. The ignition and intensity of local flame are explored with different injection pressures. Two potential solutions have been proposed to facilitate the development. The results show that injection pressure plays a critical role in controlling fuel transport into the ignition cavity T1, affecting the local equivalence ratio and local flame formation. Higher injection pressures lead to less fuel transported into cavity T1, resulting in fuel-lean local equivalence ratios and potential ignition failure. Extending the duration of ignition and injection improves ignition reliability. The suppressive effect of dense spray on local flame is the main cause of the local flame development problem. A higher injection pressure can reduce the suppressive effect and increase the intensity of downstream cavity flames. When the downstream cavity flames reach a critical intensity, the flashback of downstream cavity flame will occur, achieving global flames. The dense spray can be thinned out by very low upstream injection pressure, which can also result in global flames. [ABSTRACT FROM AUTHOR]

Combustion modes of kerosene spray in a scramjet combustor condition with different injection schemes are experimentally investigated at Mach 2.52. The study is based on two single injectors with nozzle diameters of 0.79 and 1.14 mm and two dual injectors with nozzle diameters of 0.56 and 0.72 mm, respectively. The results show that the weak combustion mode has little effect on the flow field, while the intensive combustion mode has the opposite effect. The dual injector can promote evaporation and mixing of the kerosene spray. Compared with the dual injector, intensive combustion cannot occur when a single injector is used, and the flame stability range is also narrower. As the nozzle diameter of the injector increases, the distribution and oscillation of kerosene spray change significantly, transition from the weak to intensive combustion mode occurs at a higher equivalence ratio, and the flame stability range increases. However, change in the nozzle diameter does not affect the overall process of combustion mode transition. For the single injector, intensive combustion still cannot occur when the nozzle diameter changes. In addition, change in the nozzle diameter has little effect on combustion heat release when the combustion mode remains unchanged. [ABSTRACT FROM AUTHOR]

As the pressure ratio and the turbine inlet temperature keep increasing in high performance aero-engines, the kerosene injected into the combustion chamber becomes supercritical. Thus, the traditional self-excited oscillations of the kerosene jets in the fuel–gas mixing are much more pronounced because of the drastic changes in the kerosene thermal properties, which may exacerbate the combustion instability and threaten engine efficiency and safety. In this work, an experimental study was carried out on the self-excited oscillation phenomena of supercritical kerosene injected into a swirling flow field. The injection of supercritical kerosene under different operating conditions was studied using the Schlieren technique and the proper orthogonal decomposition method. The results present that the mixing dominated oscillations of the kerosene jet are induced by the fuel–gas interaction. While the condensation dominated oscillations are due to the phase change of supercritical kerosene in the subcritical environment and the swirling flow field. The spatial distribution of the self-excited oscillations is found to be highly related to the velocity magnitude, instead of the variations in the injection temperature and pressure. The self-excited oscillations are easier to be induced in a low velocity flow field and the oscillation region moves closer to the upstream. Thermal properties also show distinct influences on the injection. At the near-critical region, the suppression effects of high injection pressure on the high-frequency (>100 Hz) self-excited oscillations are much more distinct. [ABSTRACT FROM AUTHOR]

The Mach 6-capable turbine based combined cycle engine is a potential first-stage propulsion for TSTO mission. In order to improve thrust-to-weight ratio, an innovative tandem combined ramjet engine-FABRE (Fan Augmented Air-Breathing Ramjet Engine) is designed utilizing a versatile multi-mode combustor working at both high-speed ramjet mode and low-speed turbocharged mode. Employing the strut as mixer and flame holder in multi-mode combustor presents theoretical advantages. Nonetheless, a thorough investigation into its practical feasibility and combustion characteristics is essential. This paper experimentally verifies the feasibility of strut approach in multi-mode combustor at various speeds and evaluates the effects of different strut schemes on flow field structure, thermodynamic characteristics, and combustion performance via simulation. The experimental results affirm that employing the strut scheme as a combustion organization method enables the multi-mode combustor to operate effectively under diverse inflow conditions at both high and low speeds. Simulation results further validate that these strut solutions consistently demonstrate superior combustion performance. Additionally, the influences of the strut geometry on heat release and high-temperature area are highly consistent with its effects on combustion efficiency. At low speed, wider struts lead to increased combustion efficiency, while at high speed, they initially rise before declining with further widening. Regardless of speed, increasing strut slant angle consistently reduces efficiency. At low speed, widening the strut lowers the total pressure recovery coefficient, peaking at 45° with varying strut slant angle. Conversely, at high speed, changes in strut width minimally impact, while increasing strut slant angle reduces the coefficient. These conclusions provide valuable insights for the optimization of combustion organization in the design of combined ramjet engine with a wide range of operating conditions. • An innovative Mach 6-capable combined ramjet engine is designed to enhance the thrust-to-weight ratio for TSTO. • Experimentally validating the strut scheme for combustion organization in multi-mode combustor. • Combustion characteristics are numerically investigated using different strut schemes. [ABSTRACT FROM AUTHOR]

Experiments and numerical simulations were conducted across a range of contraction ratio to investigate the detonation combustion characteristics of liquid aviation kerosene/air rotating detonation combustor. The research indicates that extremely low and high contraction ratio adversely affect the stable operation of the two-phase rotating detonation combustors. At a contraction ratio that is too low (19.03 % in the RDC discussed in this paper), the atomization and mixing properties of the two-phase fuel are poor, with a lower reaction pressure in the fresh mixture, hindering the initiation of detonation waves. On the other hand, a contraction ratio (85.7 % in the RDC discussed in this paper) that is too high enhances the energy of the detonation wave; it triggers oblique shockwave feedback, preventing the fresh mixture from entering the combustor and thus leading to the quenching of detonation waves. With an increase in the contraction ratio of outlet configurations, there is a noticeable rise in both the peak pressure and combustion efficiency of detonation waves. In contrast, the wave height gradually decreases, and the wave velocity shows a pattern of initially increasing and then decreasing. Along the axial position inside the two-phase rotating detonation combustor, the upstream detonation wave is caused by the reflected shockwaves increasing the pressure of the upstream fresh mixture. In contrast, the downstream detonation wave results from increased fresh mixture pressure and enhanced fuel atomization and mixing due to the increased contraction ratio of outlet configurations and wave feedback. So, the detonation wave exhibits a strong-weak-strong distribution characteristic. • Three-dimensional numerical simulation and experiment in a RDC with separate feeding of kerosene and air is achieved. • Two atomization and mixing structures ("Kerosene" and "Enhanced Kerosene" region) is found. • An optimal contraction ratio size enables the RDC to achieve the best operational characteristics. [ABSTRACT FROM AUTHOR]

• Accelerant facilitated fire significantly effects the detection of blood on carpet and tile surfaces. • Successful soot removal can increase detection of heat damaged blood. • Wiping is the superior soot removal method on carpet and tile samples. • There is evidential worth in recovering heat damaged blood evidence at arson scenes. Previous literature has established that recovering heat damaged body fluids is possible, however with little investigation into the effect of accelerants used in initiating arson fires. This study therefore aimed to determine whether presumptive blood detection was affected by heat damage resulting from accelerant facilitated fires. Another objective was to examine various techniques for removing soot, which is a noted barrier to blood detection. The study focused on blood deposited on household flooring materials, one porous and one nonporous surface: carpet and tile respectively. Samples were burned with butane, petrol, and kerosene then presumptively tested using the Kastle Meyer colourimetric blood detection test. Testing was then repeated following soot removal by either wiping, scraping, or using liquid latex. The "strength" of positive detections was evaluated using a scale based on reaction speed and colour intensity. Results demonstrated that accelerants weakened detection strength, although nearly all samples tested positive overall, and the impact of each accelerant on both surface types was largely similar. It was also discovered that soot removal improved the strength of blood detection results in approximately 69% of carpet and 47% of tile samples, with wiping being the superior method on both surface types. Consequently, introducing this investigative step may be critical to maximizing blood evidence recovery in arson casework. These findings indicate the worth in recovering severely burned items, particularly for evidence as crucial as blood. [ABSTRACT FROM AUTHOR]

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This study aims to develop a liquid-liquid equilibrium model to predict the Ce distribution in the extraction system based on experimental laboratory data. Extraction feed solution (Ce hydroxide in nitric acid media) and solvent (Tri Butyl Phosphate (TBP) in kerosene diluent) with a volume ratio of 1:1 at various concentrations of feed and solvent were contacted using a mechanical shaker at 150 rpm for 15 minutes. The solution was settled for 30 minutes to separate the aqueous and organic phases. Cerium concentration in the aqueous phase was analyzed using XRF, while cerium concentration in the organic phase was calculated using a mass balance. The results showed that the extraction of Ce from the Ce-hydroxide concentrate was successfully carried out using TBP 0.92 M in kerosene diluent so that the Ce extraction efficiency of 70% was obtained. The equilibrium model that has been developed was able to represent the phenomenon of the liquid-liquid equilibrium distribution in the extraction system, which was carried out with an average relative error of 8.53%. Five stages of extraction unit need to apply to achieve 90% of extraction efficiency. [ABSTRACT FROM AUTHOR]

In this article, the convective flow in a vertical layer subjected to a consistent magnetic field with nonzero gravity condition is investigated. One side of the vertical walls is heated, while the opposite side is cooling. The magnetic field strength, field orientation angle, magnetization effect, and thermal deviation of vertical walls play important roles as controlling parameters on the flow stabilization. The goal of this investigation is to analyze the flow characteristics and find out the significant distinction between water and kerosene based magnetic fluids under the variation of thermal and magnetic effects. The numerical results are obtained by the pseudo-spectral Chebyshev expansion method. The properties of all instability modes caused by three major mechanisms, namely; thermomagnetic, thermogravitational and magneto-gravitational are analyzed. In the normal magnetic field, the wave speed responds faster, and it is recognized by a relatively small wave number in water based fluid than that in kerosene based fluid. In oblique magnetic field, the waves propagate faster in both kerosene and water based fluids with the field inclination angle increases, but they still propagate slower in kerosene based fluid comparatively in water based fluid. According to the linear or non-linear magnetization law, both upward and downward propagating waves in kerosene based fluid propagate slower, and they are recognized by greater wave numbers than that in water based fluid. It is found that the basic flow in water based fluid is much more stable than in kerosene based fluid. [ABSTRACT FROM AUTHOR]

Background: At the time of the COVID-19 pandemic, devastating incidents increased due to frequent oxygen administration to patients. The dangers associated with the use of oxygen, especially through local enrichments and formation of "oxygen clouds", have been well understood for years. Nevertheless, dramatic incidents continue to occur, since fire hazard increases exponentially with oxygen concentrations above 23%. Rescue helicopters are at a particular high risk, because of technical reasons such as oxygen use in a very small space, surrounded by kerosene lines, electronic relays and extremely hot surfaces. Methods: In this study three different sized rescue helicopter models (Airbus H135, H145 and MD902) were examined. Oxygen enrichment in the cabin was measured with an oxymeter during a delivery rate of 15 l/min constant flow for 60 min. Furthermore, the clearance of the enriched atmosphere was tested in different situations and with different ventilation methods. To make the airflow visible, a fog machine was used to fill the helicopter cabin. Results: Oxygen accumulation above 21% was detected in every helicopter. After 10–15 min, the critical 23% threshold was exceeded in all three aircrafts. The highest concentration was detected in the smallest machine (MD902) after 60 min with 27.4%. Moreover, oxygen clouds persisted in the rear and the bottom of the aircrafts, even when the front doors were opened. This was most pronounced in the largest aircraft, the H145 from Airbus Helicopters. Complete and rapid removal of elevated oxygen concentrations was achieved only by cross-ventilation within 1 min. Conclusions: Oxygen should be handled with particular care in rescue helicopters. Adapted checklists and precautions can help to prevent oxygen accumulation, and thus, fatal incidents. To our knowledge, this is the first study, which analyzed oxygen concentrations in different settings in rescue helicopters. [ABSTRACT FROM AUTHOR]