冷却通道壁面上的金属对航空煤油热氧化沉积过程有一定的促进作用．针对航空煤油在金属表面的氧化结焦情况，设计了金属基底氧化沉积实验系统，研究了不同金属对航空煤油氧化沉积的影响．实验结果表明，Fe基底表面沉积量显著高于其他4种基底，沉积量为5.2 mg，而Cu和Ti表面沉积仅为0.8 mg和0.4 mg,Fe、Cr和Ni促进了脱氧和脱氢过程，并显著消耗含氧物质，而铜对喷气燃料的氧化作用最强，生成大量含氧组分，烯烃等物质被氧化后生成更多的醇和烷烃．

To investigate the sustainable use of electric fields in improving aviation fuel combustion efficiency, a ReaxFF molecular dynamics simulation was conducted using exo-TCD (exo-tetrahydrocyclopentadiene) as the major component of JP-10 fuel. The study aimed to investigate the pyrolysis efficiency and the mechanism of electric field modulation at different temperatures. It elucidates that the pyrolysis reaction activation energy and molecular motion are the key factors affected by the co-effect of temperature and electric field. A filed strength of 10−5 V/Å was shown to increase both the reaction barriers and the probability of collision for JP-10 molecule pyrolysis, which promotes a higher reaction rate in weak electric fields with high-temperature pyrolysis. The DFT calculation was used to analyze the electronic structure and reaction potential of the JP-10 molecule under the electric field, which further discloses the effect mechanism of electric field on the pyrolysis reaction pathway. This study provides a detailed explanation of combined effects of temperature and electric field effect on aviation fuel pyrolysis to enable effective combustion of aviation fuels. © 2023

To explore the combustion efficiency of aviation fuel in an electric field, a ReaxFF molecular dynamics and density functional theory calculation was performed to study the electric field effect on 3-component RP-1 (methylcyclohexane, n-dodecane, and isododecane) pyrolysis. The electrostatic potential, charge natural population analysis and molecular structure were discussed under electric fields of various directions and strengths. The chemical reaction kinetics and species were analyzed under a wide range of electrostatic fields and temperatures. The key reaction energy of RP-1 components and motion statistics were discussed. The analysis revealed significant changes in molecular charge density and structure, which predicted possible cracking sites. Cyclohexane and chain alkanes exhibited opposite trends of decomposition rates depending on the field strength and temperature. The different trends were detail analyzed by reaction pathways and product distribution. Newly cracking way appeared under electric field. The decomposition reaction barrier was reduced by the electric field overall. While the motion of molecules was inhibited with the field increasing, which decrease the molecular potential energy. This work conducted a comprehensive analysis about effect of external electric field on the RP-1 mixture fuel pyrolysis. offering a potential solution for improving combustion efficiency. © 2023

A transient non-thermal equilibrium model was established to solve the transient process of transpiration cooling, which considers the influence of cracking reaction. The occurrence of cracking reaction leads to the increase of inlet pressure, thermal diffusion coefficient and heat transfer coefficient and effectively reduces the temperature of porous matrix. In the absence of external oscillation excitation, the change rate of porous matrix temperature and fluid temperature with heating time gradually decreases. In the case of unsteady heat flux, the oscillation amplitude of fluid parameters near the outlet of porous media is larger. The increase of thermal conductivity of solid matrix can effectively restrain the temperature oscillation caused by external heat flux, but the amplitude of coolant supply pressure increases with the increase of thermal conductivity, which is not conducive to the supply of coolant. The amplitude of reaction heat is the smallest when the frequency of coolant mass flux and heat flux is the same. The greater inlet pressure oscillation is formed when the coolant supply cycle period is lower than the cycle period of heat flux. © 2023

The electrohydrodynamic (EHD) technique can considerably improve the performance of aviation heat exchangers. In this study, the forced convection heat transfer characteristics of aviation kerosene in a horizontal wire-tube structure under electric field were investigated. The influences of positive and negative high voltages on the heat transfer in test section were compared. Key factors affecting EHD heat transfer enhancement, such as fuel inlet temperature, mass flow, heat flux and operating pressure were explored. Furthermore, the cause of electrode corrosion was investigated using Scanning Electron Microscope (SEM) and Energy Disperse Spectroscopy (EDS). The experimental results showed that the circumferential temperature distribution of the test section was uneven owing to buoyancy in the absence of electric field. As the applied voltage increased, temperature heterogeneity decreased. Negative voltage improved the heat transfer more effectively than positive voltage. The electric field enhanced the heat transfer of high-temperature fuel more effectively. In the charge injection mechanism voltage range, the numerical simulation results were more similar to the negative voltage experimental results. The heat transfer enhancement ratio was reduced by an increase in the fuel mass flow and operating pressure. A higher heat flux led to a more substantial buoyancy effect, which inhibited the electric field force effect. Finally, the corrosion rate of positive high voltage electrode was the highest, resulting in rapid loss of metal elements from the electrode surface. © 2023 Elsevier Ltd

As a hidden danger of modern aircraft, the problem of nozzle carbon deposition must be addressed. Carbon deposition prediction and suppression methods for aviation nozzles still need further study. In this study, fouling experiments of the aero swirl nozzle were conducted to analyze the deposition characteristics of each component, and the deposit distribution of nozzle under different working conditions was predicted by numerical simulation. Finally, the anti-coking effect of the TiN coating on swirl nozzle was evaluated. The results showed that the buoyancy force could lead to an uneven distribution of deposits in the fuel feed arm. High inlet temperature fuel carries more precursors and results in a swirler surface covered with deposits, whereas for low inlet temperature fuel, deposits accumulate on the boss near passages inlet. The reaction species content, local velocity and temperature determined this. The deposition layer on the nozzle orifice surface is the densest owing to the high temperature and oxygen-rich environment. The TiN coating was applied to the inside and outside of the nozzle by chemical vapor deposition (CVD). The coating protection on fuel feed arm and swirler was inconspicuous. However, it exhibited the best anti-coking effect on the orifice surface. In this study, the causes of carbon deposition in swirl nozzles were determined and the protective effect of TiN inert coating was evaluated for the first time. © 2023 Elsevier Ltd

A method for improving the swirl nozzle spray performance using electric field is proposed. A pair of symmetrical needle electrodes is arranged perpendicular to the fuel injection direction. The influence of the electrode height and distance, along with that of the voltage between electrode pair on spray morphology are studied. The results show that when the electrodes are arranged at the fuel-film breakup height, the ion wind shortens the liquid film penetration length and increases the spray angle. The average fuel drop size is reduced by up to 35.8%. The distance between the electrodes also affects the atomization performance. © 2023 Elsevier B.V.

Since the concept of aggregation-induced emission (AIE) was proposed by Benzhong Tang's research group in 2001, the exploration of the mechanism of AIE and the development of new high-performance AIE materials have been the focus and goal of this field. On the basis of a large number of experiment results, AIE mechanism has been well explained by lots of works, such as restricted intramolecular motion (RIM), J-aggregate et al. As tetraphenylethlene (TPE) molecules are stacked, the rotation of the benzene ring rotor is blocked, and the energy attenuation is released in the form of radiation, showing the AIE effect. In order to further explore the AIE effect of TPE, we performed electronic structure, spectrum simulation, and AIE mechanism calculations of the anthryl-tetraphenylethene (TPE-an) monomer and dimer in the gas phase, tetrahydrofuran (THF), and aqueous solutions at the B3LYP/6-31G** level. The calculation results show that TPE-an molecule is in a propeller-like configuration, and its fluorescence intensity is weak; compared with the monomer, the fluorescence intensity of the dimer increases by 87% in aqueous solution; the fluorescence intensity in the gas phase, THF solution, and aqueous solution gradually enhances with the increase of the degree of aggregation, which are consistent with the experimental results. The enhancement of fluorescence intensity is caused by the change of molecular structure caused by aggregation. This detailed AIE luminescence mechanism will provide theoretical guidance for AIE material design.