Kerosene Combustion Research Articles

EFFECT OF LIQUID KEROSENE DROPLET INJECTION AT VARIOUS RADIAL AND TANGENTIAL VELOCITIES ON NOX, CO FORMATION, AND TEMPERATURE DISTRIBUTION

This research presents a numerical analysis and CFD simulation of liquid kerosene combustion by means of a variation of liquid kerosene radial and tangential velocity components of injected droplets through an atomizer into a real combustor. The droplets are considered through the Rosin-Rammler droplet particle size distribution with the Eulerian-Lagrangian Spray Atomization model. The main purpose of this investigation is to evaluate the behavior of emission formations such as NO and CO, including temperature distribution fluctuations in the primary combustion zone during the combustion process and droplet evaporation. For the simulation of evaporated kerosene combustion, the flamelet model was performed for the detailed kinetic scheme of chemical reactions between (JetA-C10H22) and air, which is integrated in ANSYS CFX, including the thermal and prompt prediction of NO. The standard k-ϵ turbulence model was used with enhanced wall treatment including P1 radiation model. Verification and validation of analysis results were considered in this study, where the results, such as temperature and NO formation in various radial distances of combustor, were compared with the real experimental results. The results showed that droplet behavior, influenced by injection velocities, significantly impacts the combustion process, including temperature distribution, NOx formation, and CO emissions especially in the primary combustion zone.

Experimental Study on Scale Effects of Kerosene Combustion in Scramjet Combustors

The combustion characteristics in two geometrically similar kerosene-fueled scramjet combustors with mass flow rates of 0.69 and 1.41 kg/s are experimentally investigated to explore the scale effects of flame stabilization at Mach 2.52 condition. As the equivalence ratio increases, the combustion usually changes from weak to intensive to blow-out mode. The weak combustion has little effect on the flow field, whereas the intensive combustion has the opposite effect. The transition combustion tends to occur between different modes. When the single injector is used, compared with the small-scale combustor, intensive combustion cannot occur in the large-scale combustor, and the flame stability range is also narrower. One probable reason is that as the combustor scale increases, the boundary layer becomes relatively thinner, resulting in a smaller low-velocity zone and a faster mainstream velocity at the downstream wall of the cavity, which is not conducive to the flame propagation upstream to form the intensive combustion. After shortening the isolator, all cases with intensive combustion in the small-scale combustor are transformed into weak combustion, further confirming the speculation. Compared to the single injector, the dual injector is required in the large-scale combustor to achieve intensive combustion and a wider flame stability range.

Simplification and verification of chemical reaction mechanism of RP-3 aviation kerosene

To reveal the combustion and explosion characteristics of RP-3 aviation kerosene, a three-step simplified mechanism involving CO-CO2, H2-H2O equilibrium was constructed. Using a general program based on Cantera and genetic algorithms, the reaction rate parameters were optimized under given conditions, and a relationship between reaction rate parameters and fuel equivalence ratio was developed. The optimized mechanism was compared with multiple flame parameters under multiple operating conditions of RP-3 aviation kerosene. The results showed that the laminar flame speed and adiabatic flame temperature of the three-step simplified mechanism were in good agreement with the experimental data of RP-3 aviation kerosene within the temperature range of 300 ∼ 600 K and pressure range of 1–5 atm, with an error of less than 10 %. The optimized mechanism corrected using a correction function is in good agreement with experimental and numerical results under multiple conditions, verifying the rationality of the simplified program and the accuracy of the three-step simplified mechanism. For practical engineering issues, RP-3 aviation kerosene explosion experiments were conducted, and the pressure and flame data were analyzed and compared. The results indicated that the three-step simplified mechanism had satisfactory calculation time scales and numerical simulation feasibility.

Effect of Kerosene Dual-Jet Spacing on the Mixing and Combustion Characteristics of a Scramjet Combustor.

As the core of a hypersonic propulsion system, the effective mixing efficiency of fuel and air in a supersonic combustor is crucial for its performance. This study focuses on a cold supersonic flow and employs computational fluid dynamics (CFD) techniques combined with Euler-Lagrange method's discrete-phase model (DPM) for multiphase flows, K-H and R-T (Kelvin-Helmholtz and Rayleigh-Taylor) mixing and atomization models, turbulence models, and surface evaporation models to investigate the injection, atomization, and mixing characteristics of kerosene in supersonic airflow. In order to enhance the mixing efficiency between kerosene and air while reducing flow losses, this study examines a staggered dual-jet injection scheme, with the dual jets arranged at the center of the cavity and having a dual-jet spacing of 10 and 20 mm, respectively. Starting from the interaction mechanism between jets, the impact of different staggered dual-jet spacings on the kerosene jet penetration height, span expansion area, angle of the shock wave, and Sauter mean diameter distribution was analyzed. The results show that a short dual-jet spacing (10 mm) leads to greater penetration height, wider span expansion, and a larger angle of the shock wave. When the dual-jet spacing is shorter, the interaction between the fuel jet and the cavity shear layer is stronger, resulting in an improved fuel mixing efficiency. The achievements of this study are consistent with previous experimental measurements and the literature, demonstrating a strong theoretical foundation for optimizing the design of hypersonic engines by deepening the understanding of the fundamental atomization mechanisms of kerosene jets in cold-state supersonic flows. Moreover, these results hold practical significance in improving the efficiency of kerosene combustion and enhancing the performance of flame stabilization devices.

Experimental Investigation of Microwave-Assisted Kerosene Supersonic Combustion

ABSTRACT The microwave-assisted kerosene combustion in supersonic flow was invested experimentally using a novel microwave-flame coupling method. The experiment used a direct-connected system, with a horn antenna employed to introduce microwaves into the combustion chamber, generating a traveling wave within the cavity. The microwave field simulation results confirm this coupling method’s feasibility. The experimental results showed that with the influence of the microwave, the flame’s stable position moved upstream by 7.4 mm. The average velocity of flame propagation increased by 64% upstream of entering the cavity and by 61% upon exiting it. The specific impulse of the scramjet was increased by about 4% under a 700W continuous microwave. In the presence of hydrogen, there was a significant increase in the excitation of NO and N2. However, in hydrogen-free combustion processes, the enhancement of radicals was considerably less compared to ignition processes, suggesting a close correlation between microwave-assisted combustion and hydrogen. These experimental results validate the feasibility of the microwave-combustion coupling method, representing a novel exploration into microwave-assisted kerosene combustion that aligns more closely with the practical application scenarios of scramjet engines.

Effects of adding n-amyl alcohol, dimethylfuran to fuel on soot formation in aviation kerosene diffusion flame

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.

Estimation of Net Heat of Combustion of Light Kerosene Distillates Using Artificial Neural Networks

Estimation of Net Heat of Combustion of Light Kerosene Distillates Using Artificial Neural Networks

Effect of Gas Addition on Liquid Kerosene Combustion in a Scramjet Combustor

Experiments were conducted at Mach 2.52 to investigate the effect of gas addition on the mixing and combustion characteristics of the liquid kerosene in a scramjet combustor. Two different combustion modes (scram mode and ram mode) were achieved by varying the equivalence ratio. Flowfield diagnostic techniques, such as shadow visualization and wall pressure measurement, and Proper Orthogonal Decomposition analysis were employed to investigate the complex supersonic gas– liquid two-phase combustion flowfield. It is found that, compared to the pure high-pressure kerosene, the gas-added kerosene can achieve better combustion performance at low injection pressure. The gas addition increases the fuel-jet penetration depth and promotes flowfield fluctuations. The gas–liquid two-phase instability induces large-scale vortices within the fuel-jet shear layer. The diffusion and mixing of kerosene are enhanced by the large-scale vortices, and the rapid and intense combustion of kerosene is realized.

Experimental investigation of the effects of inlet high-swirl air preheating and dilution on kerosene flame

This study investigated the effects of co-flow air swirling on the combustion of Kerosene, as relatively heavy fuel, under preheated and diluted air conditions. Various factors affecting the flame structure, such as preheating temperature, dilution, swirl number, and airflow rate were studied using the upgraded MILD (Moderate or Intense Low-Oxygen Dilution) combustion tester of Sharif University of Technology (SMSTR). This tester, which is symmetrically axial, provides co-flow air with the desired temperature, swirl number, and dilution for a liquid fuel spray burner. The flame characteristics was investigated through direct photography and chemiluminescence. The results show that the stability range significantly increases with the air swirling, while the flame length decreases. Enhancement of combustion quality and more complete combustion of fuel were observed with preheating. Preheating resulted in geometric changes in the appearance of the flame, specially reducing flame lift-off and the front view area in high airflow. A decrease in the air oxygen content causes a general change in the structure of the flame, resulting in a shorter and more lifted one compared to non-diluted condition. The chemiluminescence images of the flame also revealed weaker and more uniform emission pattern with the inlet high-swirl air preheating and dilution. By utilizing around 15 % oxygen content dilution, preheating at around 656 K, and a swirl number of 0.8, the combustion zone exhibited similarities to the MILD combustion mode, suggesting the achievement of MILD combustion. The high swirl concept allowed higher dilution limits (about 12 %) and reduced preheating requirements (approximately 11 %) in achieving the MILD combustion regime compared to the previous study conducted without swirl conditions. In contrast to the non-swirl mode flame, the flame in this study transitioned completely to a MILD-like condition.

Kinetic Models of Combustion of Kerosene

Kinetic Models of Combustion of Kerosene

Analysis of environmentally friendly commercial aviation development ways

The goal of this study is to identify effective directions to decrease the greenhouse gas emissions of commercial aviation. The subject matter of this research is to analyze ways known from literature to decrease the greenhouse gas emissions of commercial aviation: continued evolution (which includes a lot of various methods for partial reduction of greenhouse gas emissions with decreasing in fuel consumption), «net zero» (which includes the following methods: offsets and sustainable aviation fuel utilization), electric hybrid power plants (parallel, series, series/parallel, turboelectric, and partial turboelectric), «zero carbon» (replacing kerosene combustion with hydrogen combustion in modified gas-turbine engines), «true zero» (transition to electric cruise motors with hydrogen fuel cells or electric batteries). The tasks to be solved are as follows: learning of the ways and detection of advantages and problems from the point of view of efficiency, technical complexity, economy, ecology, and implementation possibility in conditions of limited funding. The methods used are: search of the corresponding information sources in the Internet and their analysis on the basis of operational experience in the aviation branch. The following results were obtained: in terms of found information sources, data about existing greenhouse gas emissions and their predictive estimations, history of international agreement development as for greenhouse gas emission reduction were briefly stated; actuality of this problem with a view to mitigate the environmental impact was stressed; and the advantages and problems, which should be solved to implement each of the considered ways, were summarized. Conclusions. The scientific novelty of the results obtained is as follows: 1) information from numerous sources of literature that clarifies classification, the advantages, and the problems that should be overcome for each ways implementation, was summed up in the review article; 2) additional inherent disadvantages, which are integral to some of the ways (low efficiency, high technical complexity, schedule delays, cost overruns, funding instability, doubts in their reasonability from ecological considerations), are shown as a result of analysis and historical analogy. The direction of the following research in this field is outlined.

Contrail formation on ambient aerosol particles for aircraft with hydrogen combustion: a box model trajectory study

Abstract. Future air traffic using (green) hydrogen (H2) promises zero carbon emissions, but the effects of contrails from this new technology have hardly been investigated. We study contrail formation behind aircraft with H2 combustion by means of the particle-based Lagrangian Cloud Module (LCM) box model. Assuming the absence of soot and ultrafine volatile particle formation, contrail ice crystals form solely on atmospheric background particles mixed into the plume. While a recent study extended the original LCM with regard to the contrail formation on soot particles, we further advance the LCM to cover the contrail formation on ambient particles. For each simulation, we perform an ensemble of box model runs using the dilution along 1000 different plume trajectories. The formation threshold temperature of H2 contrails is around 10 K higher than for conventional contrails (which form behind aircraft with kerosene combustion). Then, contrail formation becomes primarily limited by the homogeneous freezing temperature of the water droplets such that contrails can form at temperatures down to around 234 K. The number of ice crystals formed varies strongly with ambient temperature even far away from the contrail formation threshold. The contrail ice crystal number clearly increases with ambient aerosol number concentration and decreases significantly for ambient particles with mean dry radii ⪅ 10 nm due to the Kelvin effect. Besides simulations with one aerosol particle ensemble, we analyze contrail formation scenarios with two co-existing aerosol particle ensembles with different mean dry sizes or hygroscopicity parameters. We compare them to scenarios with a single ensemble that is the average of the two aerosol ensembles. We find that the total ice crystal number can differ significantly between the two cases, in particular if nucleation-mode particles are involved. Due to the absence of soot particle emissions, the ice crystal number in H2 contrails is typically reduced by more than 80 %–90 % compared to conventional contrails. The contrail optical thickness is significantly reduced, and H2 contrails either become visible later than kerosene contrails or are not visible at all for low ambient particle number concentrations. On the other hand, H2 contrails can form at lower flight altitudes where conventional contrails would not form.

Gas Temperature Distribution in the Combustion Chamber of a GTM400 MOD Turbojet Engine Powered by JET A-1 Fuel and Hydrogen

Research on engine operation using hydrogen may enable appropriate optimization of thrust, and therefore performance, related to its potential use in aircraft. It is particularly important as the share of hydrogen in combustion affects the reduction of combustion products such as carbon dioxide, carbon monoxide, nitrogen oxide, hydrocarbons, and solid matter. This is in line with the new requirements regarding the increased supply of sustainable aviation fuels (SAFs) and the related changes in emissions, i.e., reducing the harmful impact of exhaust gases on the environment. This paper presents the results of measurements carried out in the GTM400 MOD turbojet engine. Based on the research performed, the impact of hydrogen and aviation kerosene combustion on selected engine parameters is presented. The paper shows changes in the rotational speed and volume flow of JET A-1 fuel as a function of engine operation time. Changes in temperature measured at the edge of the flame tube were also examined. The tests confirmed that the combustion chamber worked correctly in the selected area in the range of the tested fuel mixtures. After incorporating hydrogen into the combustion process, the consumption of traditional JET A-1 fuel was significantly reduced.

Experimental Study of Kerosene Combustion Characteristics in a Jet of Superheated Steam with a Controlled Air Excess

Experimental Study of Kerosene Combustion Characteristics in a Jet of Superheated Steam with a Controlled Air Excess

Comparison of the Flame Dynamics of a Liquid-Fueled Swirl-Stabilized Combustor for Different Degrees of Fuel-Air Premixing

Abstract This study investigates the flame dynamics of lean premixed kerosene combustion for two different degrees of fuel–air premixing using a swirl stabilized burner with an axially movable twin fluid fuel injection nozzle. Thermal power, equivalence ratio, and atomizing air mass flow are varied systematically for both nozzle positions investigated. Measurements of the droplet size distribution at the nozzle exit are provided for all operation points. NOx emission measurements and OH*-chemiluminescence flame images show that stationary combustion characteristics significantly change with the nozzle position. Flame Transfer Functions (FTFs) are presented and interpreted for all operation points. The FTFs for the two configurations differ most in the low frequency range where the influence of the droplet dynamics is expected to be highest. For both configurations, a change in thermal power does not affect droplet size, flame shape, NOx emissions, and FTF. The observed trends in response to changes in equivalence ratio and atomizing air mass flow are opposite for both configurations. NOx emissions and flame shape are independent of the atomization air mass flow in the highly premixed configuration but not in the partially premixed configuration. In contrast to this, the FTF is affected by changes of the atomization air mass flow in both configurations, but again the trends are opposite. The observed trends for the highly premixed configuration are modeled and reproduced by a change in the phase relation between the equivalence ratio fluctuations and other instability driving mechanisms.

An electricity supply system by recovering the waste heat of commercial aeroengine

Rapid development of the aviation industry has brought great convenience to people's travel and goods transportation. The inevitable issues are high level of energy consumption and the huge environment pollution by kerosene combustion. On the other hand, there is a greater requirement for the electricity capacity as well as the power ratings of aircraft generators to meet the continuous intensification of the electrification degree in modern aircraft. The question that is tried to identify in this paper is: can the waste heat in the aircraft be collected to generate power for meeting the electricity demand? In this paper, an electricity supply system driven by the heat collected from the commercial aeroengine wall is first proposed. It is an integrated system by coupling the topping gas turbine with bottomed closed Brayton cycle via the liquid sodium. A comprehensive mathematical model is developed for the system in the aspects of thermodynamics and economics. The analysis results demonstrate that the proposed system is capable of satisfying the megawatt-scale power requirements of commercial aeroengine. The fluid He–Xe (40 g/mol) is a better choice to cycle the given power system than He and air considering its larger net power output, lower compression ratio and smaller component size. The system with He–Xe can supply 1299 kW electricity power when the compression ratio is just about 7.1. In that case, the oil cost savings is about 3.66 percentages lower than that of the original oil consumption.

Effect of injection strategy on an air-assisted direct injection aviation kerosene two-stroke engine

In small aviation piston engines, the atomization and combustion of aviation kerosene have attracted much attention. Due to the low volatility and high viscosity of aviation kerosene, high-pressure injection or air-assisted injection is used to improve the fuel atomization quality. Considering the weight, cost and power consumption, air-assisted injection is more appropriate for compact, small aviation piston engines. In the paper, computational fluid dynamics (CFD) software was used to simulate the air-assisted spray and spark ignition combustion of aviation kerosene in a heavy-fuel direct injection spark ignition (DISI) two-stroke engine based on air-assisted direct injection (AADI) technology. The effects of injection pressure, single and double injection on formation and combustion characteristics of the aviation kerosene/air mixture were analyzed. The results show that increasing the air-assisted injection pressure can promote air flow in the cylinder and accelerate fuel evaporation, but also increase the film mass on the combustion chamber wall. When single injection is employed, high combustion pressure and temperature are generated, and the tendency to knocking combustion is greater. The use of double injection can effectively achieve fuel stratification and reduce knock tendency. With the delay of the second mixture injection timing, the peak combustion pressure is reduced, the heat release rate is slowed down, and the knock tendency is reduced correspondingly.

Combustion of Kerosene in a Supersonic Flow at Mach Number M = 1.7 Under the Action of Gas-Dynamical Pulses

Combustion of Kerosene in a Supersonic Flow at Mach Number M = 1.7 Under the Action of Gas-Dynamical Pulses

Time-resolved multi-parameter detection in a kerosene-fueled combustor using tunable diode laser absorption spectroscopy

Non-contact and real-time measurements for species concentration and temperature with high-time resolution in practical combustion environments are desired. A laser absorption system was developed for simultaneous sensing of CO, H2O concentrations and temperature with 1 kHz in a centrally staged kerosene-fueled combustor. An absorption feature near 4.98 μm in the mid-infrared region was selected for CO detection to minimize spectral interference with other combustion species in the kerosene combustion environment. Two spectral lines of H2O near 1.4 μm were used for temperature and H2O detection using a direct scan absorption strategy. The method of the developed multi-parameter measurement was validated in a laboratory-scale flat flame under various equivalence ratios. Comparisons were made between the experimental and theoretical results within the error of 5%. Time-resolved and in-situ measurements of temperature, H2O and CO concentration in the practical kerosene-fueled staged combustor were demonstrated. The transient characteristics of CO emission in different conditions were captured experimentally. It is found that the fluctuation amplitude of CO concentration increases as the equivalence ratio decreases during the pilot stage work only. There is a dramatic rise in CO emissions during the transition of combustion conditions. Strong fluctuation occurs with a low frequency at 32 Hz near lean blowoff. The location of the flame surface and the dynamic pressure have a significant coupling relationship with CO emission by analyzing measured data with high time resolution simultaneously.

Rotating detonation combustion of liquid kerosene under near-ramjet limit conditions

The feasibility of using preheated kerosene and pre-evaporation to assist in liquid kerosene detonation ignition and self-sustaining combustion under near-ramjet limit conditions was investigated. Additionally, the detonation decoupling and self-sustaining mechanisms were analyzed in depth. Owing to the forced heat transfer effect of supersonic flow on kerosene droplets, self-sustaining detonation combustion could not be achieved using preheated kerosene alone. The detonation wave was still decoupled due to the forced heat exchange effect of the cold kerosene droplets on the detonation wave, even if the distribution of C12H23 reached the detonation conditions through the pre-evaporation of fuel.