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This paper aims to comprehensively clarify the research status of thermal transport of supercritical aviation kerosene, with particular interests in the effect of cracking on heat transfer.

A brief review of current research on supercritical aviation kerosene is presented in views of the surrogate model of hydrocarbon fuels, chemical cracking mechanism of hydrocarbon fuels, thermo-physical properties of hydrocarbon fuels, turbulence models, flow characteristics and thermal performances, which indicates that more efforts need to be directed into these topics. Therefore, supercritical thermal transport of n-decane is then computationally investigated in the condition of thermal pyrolysis, while the ASPEN HYSYS gives the properties of n-decane and pyrolysis products. In addition, the one-step chemical cracking mechanism and SST k-ω turbulence model are applied with relatively high precision.

The existing surrogate models of aviation kerosene are limited to a specific scope of application and their thermo-physical properties deviate from the experimental data. The turbulence models used to implement numerical simulation should be studied to further improve the prediction accuracy. The thermal-induced acceleration is driven by the drastic density change, which is caused by the production of small molecules. The wall temperature of the combustion chamber can be effectively reduced by this behavior, i.e. the phenomenon of heat transfer deterioration can be attenuated or suppressed by thermal pyrolysis.

The issues in numerical studies of supercritical aviation kerosene are clearly revealed, and the conjugation mechanism between thermal pyrolysis and convective heat transfer is initially presented.

The purpose of this paper is to investigate the knock combustion characteristics, including the combustion pressure, heat release rate (HRR) and knock intensity of aviation kerosene fuel, that is, Rocket Propellant 3 (RP-3), on a port-injected two-stoke spark ignition (SI) engine.

Experimental investigation using a bench test and the statistical analysis of data to reflect the knock combustion characteristics of the two-stroke SI unmanned aerial vehicle (UAV) engine on RP-3 kerosene fuel.

Under the full load condition of 4,000 rpm, at the ignition timing of 25 degree of crank angle (°CA) before top dead centre (BTDC), the knock combustion is sensitive to the thinner mixture; therefore, the knock begins to occur when the excess air ratio is larger than 1.0. When the excess air ratio is set as 1.2, the knock obviously appears with the highest knock intensity. At the excess air ratio of 1.2, better engine performance is obtained at the ignition timing range of 20-30 °CA BTDC. However, the ignition timing at 30° CA BTDC significantly increases the peak combustion pressure and knock intensity with the advancing heat release process.

Gasoline has a low flash point, a high-saturated vapour pressure and relatively high volatility, and it is a potential hazard near a naked flame at room temperature, which can create significant security risks for its storage, transport and use. The authors adopt a low-volatility single RP-3 kerosene fuel for all vehicles and equipment to minimise the number of different devices using various fuels and improve the military application safety.

Most two-stroke SI UAV engines for military applications burn gasoline. A kerosene-based fuel for stable engine operation can be achieved because the knock combustion can be effectively suppressed through the combined adjustment of the fuel amount and spark timing.

The purpose is to forecasting carbon emissions from China's civil aviation more accurately, a novel fractional multivariate GM(1,N) model with interaction effects is developed in this paper.

First, the interaction term, the trend terms are introduced in the grey action term to reflect the influence of the interaction between the system-related variables on the change of the system characteristic variables and the time trend of the system development. Then fractional cumulative generating sequence is used as the modeling sequence to reduce the perturbation of the original data. Finally, in order to effectively find the optimal fraction accumulation generation coefficient, the particle swarm optimization (PSO) is used to determine the emerging coefficient.

Experimental results show that FIEGM(1, N) outperforms other grey prediction models in predicting the carbon emissions of CAAC, which can better solve the problem of multivariate system prediction of small samples with trend interaction effect.

By considering the influence of interactions in the system and the trend of system development in combination with fractional accumulation theory, a new method to improve the prediction performance of the GM(1, N) model is proposed. The model is first applied to the prediction of carbon emission of civil aviation in China.

The purpose of this paper is to compare the combustion characteristics, including the combustion pressure, heat release rate (HRR), coefficient of variation (COV) of indicated mean effective pressure (IMEP), flame development period and combustion duration, of aviation kerosene fuel, namely, rocket propellant 3 (RP-3), and gasoline on a two-stoke spark ignition engine.

This paper is an experimental investigation using a bench test to reflect the combustion performance of two-stroke spark ignition unmanned aerial vehicle (UAV) engine on gasoline and RP-3 fuel.

Under low load conditions, the combustion performance and HRR of burning RP-3 fuel were shown to be worse than those of gasoline. Under high load conditions, the average IMEP and the COV of IMEP of burning RP-3 fuel were close to those of gasoline. The difference in the flame development period between gasoline and RP-3 fuel was similar.

Gasoline fuel has a low flash point, high-saturated vapour pressure and relatively high volatility and is a potential hazard near a naked flame at room temperature, which can create significant security risks for its storage, transport and use. Adopting a low volatility single RP-3 fuel of covering all vehicles and equipment to minimize the number of different devices with the use of a various fuels and improve the application safeties.

Most two-stroke spark ignition UAV engines continue to combust gasoline. A kerosene-based fuel operation can be applied to achieve a single-fuel policy.

The purpose of this paper is to numerically investigate the heat transfer performance of aviation kerosene flowing in smooth and enhanced tubes with asymmetric fins at supercritical pressures and to reveal the effects of several key parameters, such as mass flow rate, heat flux, pressure and inlet temperature on the heat transfer.

A CFD approach is taken and the strong variations of the thermo-physical properties as the critical point is passed are taken into account. The RNG k-ε model is applied for simulating turbulent flow conditions.

The numerical results reveal that the heat transfer coefficient increases with increasing mass flow rate and inlet temperature. The effect of heat flux on heat transfer is more complicated, while the effect of pressure on heat transfer is insignificant. The considered asymmetric fins have a small effect on the fluid temperature, but the wall temperature is reduced significantly by the asymmetric fins compared to that of the corresponding smooth tube. As a result, the asymmetric finned tube leads to a significant heat transfer enhancement (an increase in the heat transfer coefficient about 23-41 percent). The enhancement might be caused by the re-development of velocity and temperature boundary layers in the enhanced tubes. With the asymmetric fins, the pressure loss in the enhanced tubes is slightly larger than that in the smooth tube. A thermal performance factor is applied for combined evaluation of heat transfer enhancement and pressure loss.

The asymmetric fins also caused an increased pressure loss. A thermal performance factor ? was used for combined evaluation of heat transfer enhancement and pressure loss. Results show that the two enhanced tubes perform better than the smooth tube. The enhanced tube 2 gave better overall heat transfer performance than the enhanced tube 1. It is suggested that the geometric parameters of the asymmetric fins should be optimized to further improve the thermal performance and also various structures need to be investigated.

The asymmetric fins increased the pressure loss. The evaluation of heat transfer enhancement and pressure loss Results showed that the two enhanced tubes perform better than the smooth tube. It is suggested that the geometric parameters of the asymmetric fins should be optimized to further improve the thermal performance and also various structures need to be investigated to make the results more engineering useful.

The paper presents unique solutions for thermal performance of a fluid at near critical state in smooth and enhanced tubes. The findings are of relevance for design and thermal optimization particularly in aerospace applications.

It has been said that oil price shocks affect stock market returns. However, empirical studies remain inconclusive regarding the nexus between oil price shocks and stock market returns. Consequently, the purpose of this study is to investigate the asymmetric impact of oil price shocks on stock returns in Nigeria.

A two-stage Markov regime-switching approach is used to examine the asymmetric effects of three different structural oil shocks on stock returns. The oil shocks, which include oil supply shock, aggregate demand shock and oil-specific demand shock, are derived using structural vector autoregressive. Monthly data that spans the period between January 1990 and December 2018 are deployed for estimation.

The linear estimation results show that only oil demand shock negatively and significantly affects the stock market returns. The Markov-switching regime results reveal that oil supply shock has a significant positive impact on the stock returns in a low-volatility state, whereas oil-specific demand shock negatively impacts the stock returns in a high-volatility state.

There is a need for policymakers and investors to take cognizance of not only the positive outcomes of a relatively stable state of oil price but also the negative consequences of a high-volatility state when formulating policy and making investment decisions, respectively.

This study differs from other similar studies in Nigeria that have examined the asymmetric relationship between oil price shocks and stock market return by using a two-stage Markov regime-switching approach. To the best of the authors’ knowledge, this is the first attempt at using this methodology.

The purpose of the conducted investigations is assessment of performance improvement of hybrid gas-turbine engine (HGTE) based on solid oxide fuel cell (SOFC) using cheaper and environmental alternative fuels (AF) such as liquid methane and propane – butane mixture (propane – butane). This paper also assessed the efficiency of mid-flight propulsion system (PS) based on HGTE for advanced short – medium hall aircrafts (SMHA) of 2025 (with level of parameters corresponding to technologies of 2025-2030 time period).

According to purposes of this paper, following are conducted: Analysis of properties of conventional and advanced aviation fuels, updating of architectures and parameters of energy system of HGTE based on SOFC using different fuels (kerosene, methane and propane – butane). Examination of rational architectures and updating of possible design parameters of HGTE using different types of fuel. Assessment of efficiency of PS with HGTE using different fuels under aircraft criteria. Assessment of emission of harmful substances and acoustical efficiency of SMHA with HGTE using different fuels.

Improvement of technical and environmental performances of SMHA with HGTE based on SOFC using AF in comparison with turbofan is shown.

Accuracy of research results is defined by a number of the adopted aircraft and engine restrictions, as well as accuracy of prediction concerning to the improvement of integral characteristics of elements SMHA and PS with HGTE for 2025.

Advantages of HGTE based on SOFC create good preconditions for initiation of works on development of new-generation aircrafts using AF after 2025.

Development of SOFC technologies result in evolution of new high-economic and environmental friendly hybrid gas-turbine PS for aircrafts using AF, Improvement of an environmental situation around the airport, decrease of CO₂ emission for full-flight cycle, creation of scientific and technological base for transition to electric PS of full electric aircraft.

Research results show that application of AF increases efficiency of electrochemical generator (ECG) based on SOFC and fuel efficiency of whole engine, which enable to use HGTE for PS of advanced aircrafts more effectively than turbofan. As distinct from storage battery (Bradley et al., 2010) and ECG based on Polymer Electrolyte Membrane Fuel Cell (Horyson Energy Systems, 2010), specific characteristics of ECG based on SOFC using methane allow to design PS for SMHA of 2025.

To examine the role of new aeronautical technologies in improving commercial aviation’s environmental performance.

Reviews the environmental improvements that may be conferred through the adoption of alternative aviation fuels and new airframe, engine and navigation technologies.

Although aeronautical technologies have evolved considerably since the earliest days of powered flight, the aviation industry is now reaching a point of diminishing returns as growing global consumer demand for air transport outstrips incremental improvements in environmental efficiency. The chapter describes some of the technological interventions that are being pursued to improve aviation’s environmental performance and discusses the extent to which these innovations will help to deliver a more sustainable aviation industry.

RECENT testing has involved the fuel modifier ‘Avgard’ developed by ICI Paints Division which is designed to suppress post crash fuel fires by preventing aviation kerosene from misting. Aircraft fuel escaping from ruptured tanks after an impact forms a fine mist which is easily ignited but this misting does not occur when the fuel is treated with Avgard.

This paper aims to study the influence of microparticles on the surface cavitation behavior of 2Cr3WMoV steel; microparticle suspensions of different concentration, particle size, material and shape were prepared based on ultrasonic vibration cavitation experimental device.

2Cr3WMoV steel was taken as the research object for ultrasonic cavitation experiment. The morphology, quantity and distribution of cavitation pits were observed and analyzed by metallographic microscope and scanning electron microscope.

The study findings showed that the surface cavitation process produced pinhole cavitation pits on the surface of 2Cr3WMoV steel. High temperature in the process led to oxidation and carbon precipitation on the material surface, resulting in the “rainbow ring” cavitation morphology. Both the concentration and size of microparticles affected the number of pits on the material surface. When the concentration of microparticles was 1 g/L, the number of pits reached the maximum, and when the size of microparticles was 20 µm, the number of pits reached the minimum. The microparticles of Fe3O4, Al2O3, SiC and SiO2 all increased the number of pits on the surface of 2Cr3WMoV steel. In addition, the distribution of pits of spherical microparticles was more concentrated than that of irregularly shaped microparticles in turbidity.

Most of the current studies have not systematically focused on the effect of each factor of microparticles on the cavitation behavior when they act separately, and the results of the studies are more scattered and varied. At the same time, it has not been found to carry out the study of microparticle cavitation with 2Cr3WMoV steel as the research material, and there is a lack of relevant cavitation morphology and experimental data.