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Liquid film cooling by jet–wall impingement on the combustor wall is commonly used in small rocket engines. The heat transfer mechanism inside the liquid film is closely related to the film flow. Therefore, we establish a comprehensive analytical model with reasonable assumptions for the liquid film flow by inclined jet–wall impingement, and we validate it through a series of experiments. It is found that the predicted liquid film dimensions agree well with the experimental results. As the impingement angle increases from 30 to 60 deg, the shape of the liquid film turns from an oval to a circle. With the increase of the impingement velocity from 7.8 to [Formula: see text], the width, length, and area of the liquid film increase. The wall roughness [Formula: see text] ranges from 6.3 to [Formula: see text], which shows negligible effects on the liquid film dimensions. As the surface tension increases from 36.03 to 67.13 mN/m and the viscosity increases from 1 to [Formula: see text], the dimensions of the liquid film decrease. The effect of viscosity is more significant than surface tension within the scope of this experiment. Finally, an empirical correlation for the three investigated film dimensional parameters is proposed.

A thin-sheet splash of a droplet impact on a solid surface typically appears as secondary droplets are ejected from a levitated liquid lamella. A recent work (Qin, M.; Tang, C.; Guo, Y.; Zhang, P.; Huang, Z.

A long series of runoff data is the basis for water conservancy project planning, water resource management, and so on. When the runoff data is in short supply, it needs to be extended and reconstructed. Taking Zhiyan Reservoir and Qiantanglong Reservoir in Lanxi City as the research objects, based on the Water balance model with double parameters (WBM-DP) and Quantile Mapping (QM) methods, the monthly income of the two reservoirs for 59 years from 1960 to 2018 was analyzed. The library runoff sequence was refactored. The constructed WBM-DP has good calibration results, extending the monthly inflow runoff sequence of Zhiyan Reservoir and Qiantanglong Reservoir. After the QM method is used to correct the deviation, the error between the simulated series and the measured value is significantly reduced. The method used in this paper can provide reference for the reconstruction of long series of runoff data.

Jun Wang,1,2 Yulin Zhai,1 Mingguang Ou,3 Yunfeng Bian,4 Chenglong Tang,5 Wanchao Zhang,6– 8 Yujiao Cheng,1,2 Guijie Li1,2 1Citrus Research Institute, Southwest University, Chongqing, People’s Republic of China; 2National Citrus Engineering Research Center, Chongqing, People’s Republic of China; 3Guang’an Nongfeng Agricultural Development Co., Ltd, Sichuan, People’s Republic of China; 4Guang’an Zheng Wang Agriculture Co., Ltd, Sichuan, People’s Republic of China; 5Yuanyang Hongtu Grapefruit Agricultural Technology Development Co., Ltd, Yunnan, People’s Republic of China; 6Chongqing Institute of Medicinal Plant Cultivation, Chongqing, People’s Republic of China; 7National Patent Navigation Project (Chongqing) Research and Promotion Center, Chongqing, People’s Republic of China; 8Bio-Resource Research and Utilization Joint Key Laboratory of Sichuan and Chongqing, Chongqing, People’s Republic of ChinaCorrespondence: Wanchao Zhang Tel +86-13072382527Email boystory@163.comGuijie Li 15# Ganjucun, Xiema, Beibei District, Chongqing, 400712, People’s Republic of ChinaTel +86-17388209637Email liguijie@cric.cnAim: Lemon peel, a traditional Chinese medicine, was tested in this study for its novel application in inhibiting cellular oxidative stress, and the effect of lemon peel extract (LPE) on protecting H9c2 rat heart cells from oxidative stress was investigated.Methods: The scavenging effects of LPE on 1,1-diphenyl-2-picryhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) free radicals were measured in extracellular experiments. The 3-(4,5-dimethyl-2-thiazolinyl)-2,5-diphenyl-2-h-tetrazolylammonium bromide (MTT) assay was used to detect the cell survival rate. The cell supernatant and intracellular oxidation-related indicators were detected by a kit, and the mRNA expression in H9c2 cells was detected by quantitative polymerase chain reaction (qPCR). The chemical substances of LPE were analyzed by high-performance liquid chromatography (HPLC).Results: The results showed that LPE exhibited better DPPH and ABTS free radical scavenging abilities than vitamin C. Compared with the cells in the normal state (control group), the cell survival rate in the model group decreased, and the level of lactate dehydrogenase (LDH) increased, the levels of superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) decreased, and the content of malondialdehyde (MDA) increased. Compared with the control group, the expression of Bcl-2-related X protein (Bax), caspase-3, nuclear factor erythroid 2-related factor 2 (Nrf2), and heme oxygenase-1 (HO-1) in the model group was increased, and the expression of B-cell lymphoma-2 (Bcl-2) was reduced. Compared with the model group, LPE treatment improved the cell survival rate, reduced the levels of LDH and MDA, increased the levels of SOD, CAT, and GSH, downregulated the expression of Bax, caspase-3, Nrf2 and HO-1, and upregulated the expression of Bcl-2. The composition analysis showed that LPE contained catechin, rutin, naringin, quercetin, and hesperidin.Conclusion: The results indicated that LPE could protect H9c2 cells from oxidative stress through five active components. LPE has the potential to be developed into natural medicine or health food for the inhibition of cell oxidative damage.Keywords: lemon peel, oxidative stress, H9c2 rat heart cell, mRNA expression, HPLC

The potential energy surfaces (PESs) of three nitrotoluene isomers, such as p-nitrotoluene, m-nitrotoluene, and o-nitrotoluene, have been theoretically built at the CCSD(T)/CBS level. The geometries of reactants, transition states (TSs) and products are optimized at the B3LYP/6-311++G(d,p) level. Results show that reactions of -NO2 isomerizing to ONO, and C-NO2 bond dissociation play important roles among all of the initial channels for p-nitrotoluene and m-nitrotoluene, and that the H atom migration and C-NO2 bond dissociation are dominant reactions for o-nitrotoluene. In addition, there exist pathways for three isomer conversions, but with high energy barriers. Rate constant calculations and branching ratio analyses further demonstrate that the isomerization reactions of O transfer are prominent at low to intermediate temperatures, whereas the direct C-NO2 bond dissociation reactions prevail at high temperatures for p-nitrotoluene and m-nitrotoluene, and that H atom migration is a predominant reaction for o-nitrotoluene, while C-NO2 bond dissociation becomes important by increasing the temperature.

C2H4/N2O has recently been proposed as a promising monopropellant for hydrazine replacement. In this work, the auto-ignition capability of argon diluted C2H4/N2O was experimentally investigated firstly in a rapid compression machine by detecting the light emission and the pressure evolution profiles. The auto-ignition boundary temperature which separates the non-ignition and successful ignition cases was then determined and modeled as a function of pressure and mixture composition. Results show that the auto-ignition temperature decreases with the increase of pressure and increases with the argon dilution fraction and fuel oxidizer ratio. In addition, for successful auto-ignition cases, the ignition delay times were measured and used to validate several recently developed kinetic mechanisms. A mechanism was developed and showed good agreement with the measured ignition delay time as well as the auto-ignition boundary temperature at all test conditions. Finally, the auto-ignition boundary temperatures at practical rocket engine conditions (without dilution) were numerically predicted at various pressure and fuel oxidizer ratio conditions. The model is of merit for designing the cooling system and the local flow residence time to reduce the risk of fuel line explosion and the resonance acoustic induced combustion instability in practical rocket engine.

When a droplet impacts a smooth solid surface with a sufficiently high inertia, a thin sheet is created and the whole droplet fluid then breaks apart. Latka, A. [Thin-sheet creation and threshold pressures in drop splashing.

C22H15N3Cl2F6O4S, monoclinic, P1̄ (no. 14), a = 13.6099(10) Å, b = 12.0571(9) Å, c = 16.2351(13) Å, α = 90°, β = 112.714(2)°, γ = 90°, V = 1146.7(7) Å3, Z = 4, R gt(F) = 0.0419, wR ref(F 2) = 0.1087, T = 173 K.

The low to intermediate temperature (850–1050 K) auto-ignition characteristics of furan, 2,3-dihydrofurn and tetrahydrofuran have been investigated both experimentally and kinetically. The pressure (18 and 33 bar) and equivalence ratio (0.5, 1.0 and 2.0) effects on the auto-ignition of furan were experimentally examined using a rapid compression machine. Compared with alkylated furans, the ignition delay times of furan show notably insensitivity to equivalence ratio. Comparison on the low to intermediate temperature reactivity of furan, alkylated furans, 2, 3-dihydrofuran, and tetrahydrofuran indicates that saturation degree plays a more dominant role in enhancing reactivity than alkyl substitution. Literature mechanisms were validated against present data. Kinetic analyses revealed the major fuel consuming routes and the causes for the deviation between simulation and experimental results. Furthermore, a modified model of furan, 2, 3-dihydrofuran, and tetrahydrofuran was proposed and validated against the ignition delay times in this study as well as experimental data in literatures.

Liquid films created by inclined jet-wall impingement are commonly seen in industrial applications. We investigated the liquid film behaviors created by an inclined jet impinging on a vertical glass wall using a brightness-based laser-induced fluorescence method. It was found that the typical liquid film by an inclined jet-wall impingement consists of the thin layer zone, the raised zone, the liquid node, and the trailing edge. The liquid film expands with higher impingement velocity but keeps the same elliptical shape. A normalized linear correlation is proposed to estimate the liquid film thickness. Based on the continuity equation and the empirical convection model, the Reynolds number distribution is deduced from the film thickness distribution. The Reynolds number in the thin layer zone is less than the critical Reynolds number. The surface waves in the thin layer zone are divided into the ripple waves and the disturbance waves. The disturbance waves have a larger wavelength and amplitude than the ripple waves. The quantitative measurement of the disturbance waves shows that the wavelength and amplitude increase linearly along the radial distance. The smaller impingement velocity does not change the growth rate of the wavelength but accelerates the development of the amplitude.

C20H10N4Cl2F6O2S, monoclinic, P21/n (no. 14), a = 11.5523(17) Å, b = 16.120(2) Å, c = 13.0228(18) Å, β = 114.297(2)°, V = 2210.3(5) Å3, Z = 4, R gt(F) = 0.0578, wR ref(F 2) = 0.1699, T = 173 K.

Rapid compression machine (RCM) is a widely-used experimental instrument for measuring ignition delay time (IDT) in the low-to-intermediate temperature range. In this work, to enhance the validity of the “adiabatic core” approximation in RCM, a piston crevice for suppressing the piston-driven vortex and therefore promoting the temperature homogeneity in the combustion chamber was firstly optimized by numerical simulation with a dynamic mesh strategy. Results show that crevice volume should be large enough to contain most of the boundary layer cold gas during the compression so as to assure the temperature homogeneity in the reaction chamber. While the shape of the crevice (with sufficiently large volume) only weakly affects the temperature homogeneity. An optimized piston was tested across wider ranges of pressure, the chamber length, and inert gas under experimental conditions. Based on the optimized piston crevice, a RCM was established and tested. Test results have confirmed that the crevice shape does not affect the IDT measurements, provided the crevice volume fixed. In addition, the present IDTs show consistency with those using other RCMs, as well as with the numerical predictions obtained by using the well-recognized and validated kinetic mechanisms, which support the validity of the present RCM facility for ignition delay measurement.

The role of liquid viscosity on droplet spreading behavior upon impacting on a smooth stainless steel surface has been experimentally investigated. Results show the droplet spreading dynamics with increasing viscosity (characterized by the Ohnesorge number, Oh) exhibits complex dependence on the impact inertia (characterized by Weber number, We). Specifically, for a small impact inertia (We 240), droplet splashing emerges and then vanishes with increasing Oh, although βmax still decreases monotonically. All the observed phenomena imply that liquid viscosity may have a dual role in affecting the droplet spreading, which previous models of βmax do not take into account.

New ignition delay times (IDTs) of binary methylcyclohexane (MCH)/ethanol fuels were provided by using a rapid compression machine. Results show that MCH exhibits typical negative temperature coefficient (NTC) regime bounded by two turnover temperatures (Tupper and Tlower). As the ethanol blending ratio increases, IDTs increase, NTC regime shrinks and shifts to the lower temperature. Measured data are then used to validate the most updated kinetic model (Bissoonauth et al. Proc Combust Inst 2018), which well captures the IDT and NTC behavior dependence on the ethanol blending ratio. The kinetic reason for the experimentally observed ignition behavior is that ethanol addition reduces the low temperature heat release and slows down the temperature rise and H2O2 decomposition pathway activation. The mole fraction of ROO and QOOH decrease rapidly due to the reduction of MCH initial concentration, and the NTC behavior becomes less apparent consequently. Further comparison among the ignition behavior of the different binary fuels have been conducted to access the effect of ethanol addition on different structure fuels. Results indicate a generalized effect of ethanol addition and the kinetic reason is that the presence of ethanol just simply reduces the hydrocarbon concentration without fuel-to-fuel interactions.

The principal objective of the present work is to experimentally investigate the time-resolved spray characteristics. Droplets data in a dilute region of a high-pressure diesel spray were obtained by employing the PDIA (particle/droplet image analysis) method with double pulse laser illumination. Eulerian specification was adopted to describe the transient spray microscopic behavior within a fixed test window at ten representative instants after triggering the injection. The experimental results indicate that the transient spray evolution can be characterized in three distinct stages. During stage I (the latency stage), the spray tip develops and reaches the test location, but no discrete droplets were clearly observed. During stage II, the spray passes through the test window, from which discrete droplets are observed to disperse in the dilute region and the SMD of the droplets increases rapidly. During stage III, bulk spray disappears in the test window and only discrete droplets were observed. The SMD of the droplets is decreased to a “steady-state” value. Based on these sampled and processed data, the droplet size distribution functions were obtained and compared with the Rosin-Rammler and the Nukiyama-Tanasawa function. Finally, the Stokes number and the Weber number of each droplet were determined, and the movement of the droplets were analyzed. The measured time dependent droplet behaviors are believed to provide important data for spray modeling and simulation.

Due to the increased interest on understanding the combustion chemistry of the larger alkyl aromatic as jet fuel surrogate component, we provide new ignition delay time data of 1,3,5-trimethylbenzene/O2/Ar mixtures, for the temperature range between 880 and 1090 K, at the pressure of 20.0 and 30.0 bar and for different mixture equivalence ratio and fuel concentration, by using a well validated rapid compression machine with heating system. Measurements show that no negative temperature coefficient behavior was observed for this fuel. Subsequently, these low temperature ignition delay time data were used to validate several kinetic mechanisms including those of Gudiyella and Brezinsky (Combust Flame 2012), Dievart et al. (Fuel 2013), and Wang et al. (Combust Flame 2018), all of which significantly overestimate the reactivity of 1,3,5-trimethylbenzene in this temperature range. Sensitivity analysis at typical condition and comparisons of the rate constants of the ignition dominant reactions in different models indicate that a more complete reaction scheme for 1,3,5-trimethylbenzene (T135MB) and more accurate rate constant should be further pursued, especially for the reactions of H abstraction from T135MB and fuel radical consumption reactions. Finally, ignition delay times of toluene is lower than T135MB and n-propylbenzene at the same condition, which indicate that the larger number of side chain and the longer side chain length enhances the low temperature reactivity. In addition, for the same fuel isomer, the effect of the side chain length is stronger than the number of side methyl in accelerating ignition since n-propylbenzene presents an even shorter ignition delay times than T135MB. We believe the present work will be of merit for future jet fuel surrogate model development.

Ignition delay times of the nitromethane (NM)/O2/Ar mixtures were measured behind reflected shock waves in the temperature range of 1200–2000 K, pressures of 2.0 and 10.0 atm, equivalence ratios of...

The potential energy surface (PES) of nitrobenzene isomers has been built by CCSD(T)/CBS methods. The geometries of isomers and transition states (TSs) are optimized at BHANDHLYP/6-311++G (d, p) level. Sixteen isomers and fifteen isomerization reactions of nitrobenzene were found. The rate constants for the isomerization reactions are calculated and compared according to different types of isomerization. The rate constants and activation energies (Ea) of all reactions are fitted using a qusi-Arrhenius equation. Branching ratios of the nitrobenzene isomerization reactions and the previously reported decomposition reactions are compared and the isomerization to C 6 H 5 O NO followed by cleavage of O NO dominates the decomposition of nitrobenzene at low temperature.

The potential energy surfaces (PESs) of three nitrotoluene isomers, such as p-nitrotoluene, m-nitrotoluene, and o-nitrotoluene, have been theoretically built at the CCSD(T)/CBS level. The geometries of reactants, transition states (TSs) and products are optimized at the B3LYP/6-311++G(d,p) level. Results show that reactions of -NO2 isomerizing to ONO, and C-NO2 bond dissociation play important roles among all of the initial channels for p-nitrotoluene and m-nitrotoluene, and that the H atom migration and C-NO2 bond dissociation are dominant reactions for o-nitrotoluene. In addition, there exist pathways for three isomer conversions, but with high energy barriers. Rate constant calculations and branching ratio analyses further demonstrate that the isomerization reactions of O transfer are prominent at low to intermediate temperatures, whereas the direct C-NO2 bond dissociation reactions prevail at high temperatures for p-nitrotoluene and m-nitrotoluene, and that H atom migration is a predominant reaction for o-nitrotoluene, while C-NO2 bond dissociation becomes important by increasing the temperature.

Combustion and flame 226, 229-242 (2021). doi:10.1016/j.combustflame.2020.12.006, Published by Elsevier Science, Amsterdam [u.a.]

Piston creep and rebound are two non-ideal piston stopping behaviors in the rapid compression machine. Compared to nominal piston stopping, piston rebound/creep will result in a smaller/bigger 'adiabatic' core zone volume in the reaction chamber and length/shorten the ignition delay time measurements. However, the 'adiabatic core' hypothesis can still be validated under these compressions and ensures the applicability of zero-dimensional method in the model simulation. (C) 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved. This work is supported by the National Natural Science Foundation of China (51722603, and 91541107), CT is a TANG scholar and he appreciates the support from the Foundation of the National Defense Key Laboratory of Science and Technology on Combustion and Explosives. The work at NUI Galway was supported by Science Foundation Ireland (SFI) via grant awards 15/IA/3177 and 16/SP/3829. Yingtao Wu would like to thank the financial support from the China Scholarship Council (No. 201806280105). peer-reviewed 2022-05-30

In this work, we have firstly investigated the auto-ignition behaviors of 1-heptene, 2-heptene and n-heptane in the low to intermediate temperature range (650–950 K) over various equivalence ratios at 15 and 23 bar using a rapid compression machine. Results show that n-heptane exhibits the expected negative temperature coefficient (NTC) behavior and shows the shortest IDTs among the three fuels, while the NTC behavior for 1-heptene and 2-heptene is moderated and quasi-Arrhenius temperature dependence of the 1st stage IDTs is observed at all test conditions. As the temperature increased over 900 K, the IDTs of the three fuels begin to be consistent indicating a moderated effect of the unsaturated bond. In the NTC temperature region, 1-heptene shows higher reactivity than 2-heptene, while opposite relative reactivity is observed in the temperature beyond the NTC region. The IDT data of 1-heptene, 2-heptene and n-heptane were then used to validate several kinetic models. Results show that the performance of the n-heptane models is generally good, while all the models underestimate the low temperature reactivity of 1-heptene. Finally, a model refinement has been made and the prediction shows better agreement with the present measured IDT as well as the experimental pressure evolution trace in literature.