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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Wang, J.H. Huang, Z.H. Zheng, J.J. Miao, H.Y. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Effect of partially premixed and hydrogen addition on lean burn natural gas direct injection combustion was studied experimentally using a constant volume vessel. Flame propagating photos and pressure derived combustion parameters were analyzed at different premixed ratios (from 0% to 80%) and hydrogen fractions (from 0% to 40%) at overall equivalence ratio of 0.6 and 0.8, respectively. The results showed that the flame kernel was concentrated to the spark position with the increase of premixed ratio and/or hydrogen fraction. The flame propagating speed was increased with hydrogen addition to natural gas. The stable spark ignition of lean burn natural gas was realized with the combination of partially premixed direct injection combustion and hydrogen addition. Both the initial and main combustion durations were increased with the increase of premixed ratio, while they showed the decreasing trend with hydrogen addition to natural gas. Partially premixed direct injection combustion combing with hydrogen addition can achieve the stable spark ignition and fast combustion rate at the lean mixture condition. © 2009 Combustion Institute. All rights reserved.

关键词： Natural gas

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Effects of hydrogen addition on cellular instabilities of the spherically expanding propane flames 7

Effects of hydrogen addition on cellular instabilities of th...

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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Tang, C.L. Huang, Z.H. Wang, J.H. Zheng, J.J. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

An experimental study on the effects of hydrogen addition on the instabilities of spherically expanding propane-air flames was conducted in a constant volume combustion vessel over a wide range of mixture compositions and initial temperatures and pressures. The measured laminar burning velocities were compared with those of the calculated one dimensional freely propagating flames, using a recently developed detailed kinetic mechanism, and the agreement was excellent. The schlieren images show that for the fuel lean conditions, hydrogen addition increases the hydrodynamic instability due to the decreased flame thickness and increases diffusional-thermal instability due to the decreased Lewis number, while for the fuel rich conditions, the flame front is initially destabilized and later stabilized with the increase of hydrogen fraction as the results of the competing effects of hydrodynamic and diffusional-thermal instabilities © 2009 Combustion Institute. All rights reserved.

关键词： Propane

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Specific Heat Ratio of High Methane Fraction Natural Gas/Air in Confined Vessel

Specific Heat Ratio of High Methane Fraction Natural Gas/Air...

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SAE 201. World Congress and Exhibition

作者： Tang, Chenglong Si, Zhanbo Zhang, Shuang Huang, Zuohua Pan, Shiyi Wang, Jinhua Gong, Jing Xi'An Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an710049 China

The specific heat ratio used in heat release calculation plays an important role and the mass fraction burned is also a crucial parameter in thermodynamics analysis for engine combustion. A research of high methane fraction natural gas was investigated in a constant volume combustion vessel at different initial conditions. Results show that with the increase of the initial pressure, the specific heat ratio is decreased, and the time of the mixture burned up is postponed, while the peak heat release ratio is increased. With the increase of the methane fraction, the parameters have the opposite behavior. With the increase of the initial temperature, the specific heat ratio is decreased, and the time when the mixture is burned up is accelerated, and the peak heat release ratio has no obviously difference. With the increase of the dilution ratio or the CO2/N2 ratio, the specific heat ratio is decreased, and the peak heat release heat ratio is decreased. Meanwhile, the time of mixture burned up is postponed with the increase of dilute ratio or CO2/ N2 ratio. Copyright © 201. SAE International.

关键词： Specific heat

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Large eddy simulation on the respective roles of integral length scale and turbulence intensity on turbulent premixed combustion 12

Large eddy simulation on the respective roles of integral le...

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1.th Asia-Pacific Conference on Combustion, ASPACC 201.

作者： Shilong, Guo Meng, Zhang Jinhua, Wang Xutao, Wei Zuohua, Huang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The effects of integral length scale () and turbulence intensity (? ) on premixed combustion are studied using large eddy simulation. Three groups of lean CH4/air flames are carried out using the thickened flame model combined with a two-step reduced chemical mechanism. Two groups vary at constant ? and the other group increases ? from low to high while keeping unchanged. One of the cases is validated to available experimental data, showing good agreement for the flame-brush structure. The numerical results show that the increase in or ? leads to a decrease in flame-brush height and an increase in flame-brush thickness and volume. The turbulent flame speed () will be enhanced by these two factors within the scope of our study. All the flame-brush structure data, including height, thickness, volume and area, and also collapse onto a single line when the turbulent Reynolds number is used as abscissa. The probability density function distributions of filtered thickened flame front curvature show that will be increased by and ? through increasing the amount of large-scale and small-scale wrinkling structures respectively. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Large eddy simulation

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Kinetics of oxygen bubble growth in water decomposition

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Wuli Xuebao/Acta Physica Sinica 2025年第10期74卷

作者： Nie, Tengfei Xu, Qiang Luo, Xinyi Hong, Aoyue Cao, Zeshui Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

In order to enhance the efficiency of large-scale water decomposition, it is important to understand the oxygen bubble evolution on the electrode surface. In this work, a numerical model for the growth of oxygen bubbles on the electrode surface is proposed based on the dissolved oxygen flux at the bubble boundary, and the mechanisms of the reaction area and current during the bubble growth are investigated. The results show that the bubble diameters calculated from the oxygen flux at the bubble boundary are in good agreement with the diameters of the bubbles growing in the control phase of the chemical reaction. As the reaction region increases, the transition time from the diffusion-controlled stage to the chemical reaction-controlled stage becomes longer during the bubble growth. The concentration maximum value on the microelectrode surface is significantly higher than that on the large electrode surface, which leads to a steeper concentration gradient between the microelectrode surface and the bubble surface. As the current increases, the bubble growth rate increases and the time coefficient decreases faster. The bubble diameter at a current of 0.06 mA accords well with the bubble diameter at a current of 0.1.mA in the photoelectrochemical water splitting experiments. This is because the scattering of light by the growing bubbles leads to a decrease in the current density at the bottom of the bubble.(Figure Presented) © 2025 Chinese Physical Society.

关键词： Pyrolysis

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Evaluation of droplet drag force model on spray and atomization behaviours of R1.4a flashing spray 14

Evaluation of droplet drag force model on spray and atomizat...

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1.th International Conference on Liquid Atomization and Spray Systems, ICLASS 201.

作者： Zhou, Zhi-Fu Lu, Guan-Yu Zhang, Lu Chen, Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Flashing spray is of great importance in a variety of engineering fields, which occurs as the pressurized liquid is released into a low-pressure environment below its saturation pressure. This paper conducts a systematically numerical study on the spray and thermal characteristics of R1.4a flashing spray with high volatility and low saturation temperature, using a modified sprayFoam solver in the open source tool OpenFOAM-2.4.0. {1. physics involved in the complex process, including droplet flash boiling, evaporation, droplet transport, breakup, heat transfer and interaction between droplet and gas phases are taken into consideration. The emphasis is put on the droplet drag force model and nozzle diameter on flashing spray including spray morphology, droplet diameter, velocity and temperature. The result indicates that most of the drag force models have little effect on droplet diameter, velocity and temperature distributions in flashing spray, except the Khan-Richardson (K-R) model. The K-R model predicts lower temperature, higher velocity and larger size of droplet, compared to other models. The nozzle diameter greatly affects R1.4a spray morphology and tip penetration, that smaller diameter contributes to a larger radial expansion at the near nozzle region while leading to a much smaller penetration distance. This research give a useful guidance that how people choose the appropriate drag force model for simulation of flashing spray. © 201. Solar Turbines Incorporated.

关键词： Morphology

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Shock Tube Experimental and Modeling Study of MTHF Ignition Characteristics at High Temperatures

Shock Tube Experimental and Modeling Study of MTHF Ignition ...

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JSAE/SAE 201. International powertrains, Fuels and Lubricants Meeting, FFL 201.

作者： Wang, Jingshan Wang, Xibin Fan, Xiangshan Yang, Kangkang State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an710049 China

High temperature ignition delays of 2-methyltetrahydrofuran(MTHF) were measured behind a reflected shock tube under conditions of pressures from 1.2 to 1. atm, temperatures from 1.50 to 1.00 K, equivalence ratios from 0.5 to 2.0, and fuel concentrations of 0.25%, 0.5% and 1.0% diluted in argon. Results showed that the ignition delay of MTHF decreases with the increase of pressure, temperature, fuel concentration and increases with equivalence ratio. The trend is less notable at higher fuel concentrations and equivalence ratios. Based on sensitivity and pathway analysis at pressure of 1. atm, fuel concentration of 1.0%, equivalence ratio of 1.0 and temperature of 1.50K, it was found that the most sensitive reaction of MTHF at high temperature is H+O2=O+OH, and the main consumption way is fuel decomposition instead of H-abstraction. Finally, ignition delays of MTHF were compared with THF both on experimental and kinetic analyses, and MTHF has lower ignition delays than THF. To our knowledge, it is the first time to present the ignition delays of MTHF under these conditions. © 201. SAE Japan.

关键词： Shock tubes

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Measurements of premixed laminar burning velocities and Markstein lengths for isooctane-air-N2 mixtures 7

Measurements of premixed laminar burning velocities and Mark...

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7th Asia-Pacific Conference on Combustion, ASPACC 2009

作者： Ran, F. Wang, X.B. Zhu, R.J. Zhang, Z.Y. Xiang, J. Huang, Z.H. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Experiments on the laminar burning velocities and Markstein lengths for the isooctane-air-N2 blends using a constant volume combustion chamber and a high-speed schlieren photography system have been performed under different equivalence ratios, initial pressures and temperatures, and dilution ratios to determine the effect of these parameters on the laminar burning velocities. The results suggest that an decrease in initial pressure or dilution ratio and an increase in initial temperature lead to an increase in the laminar burning velocity;an increase in initial pressure and initial temperature lead to a decrease in the Markstein length. © 2009 Combustion Institute. All rights reserved.

关键词： Velocity

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Multi-Objective optimization of oil–gas cyclone separators considering liquid storage in the tank bottom

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Separation and Purification Technology 2025年 374卷

作者： Lingzi Wang Wei Du Ruiyi Liu Jianmei Feng Xueyuan Peng Feng Cao School of Energy and Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China The First Gas Plant of PetroChina Changqing Oilfield Company Jingbian Shaanxi 718500 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

As an efficient separation device, the gas–liquid cyclone separator has been widely used in oil injection compressor systems. It can effectively reduce the oil content in the high-pressure airflow, directly affecting the fuel consumption, operating efficiency, and exhaust quality parameters of compressors, making it crucial to enhance the separator’s performance. Given the critical role of geometric configuration in determining cyclone separator efficiency, this study comprehensively considers several influencing factors including the structure parameters. Taguchi method and analysis of variance (ANOVA) were used to quantify the contribution of three factors to the performance percentage of the separator, and the dual-objective optimization of the efficiency and pressure drop of the separator was carried out with the grey correlation analysis method. In the simulation calculation, this paper employs the DPM-to-VOF method coupled with the Euler wall film (EWF) to simulate the oil droplet particle separation process, featuring model transformation capabilities under specified conditions. The investigation culminates in the development of a parametric-performance prediction model and establishes optimal operational parameters for cyclone separators: the inlet velocity ( v in ) should be set at 24.49 m/s, the height of the inner cylinder of the separator tank (H t ) should be 1.2 times the diameter, and the buffer height between the inner cylinder and the liquid surface (H m ) should be 0.9 times the diameter.

关键词： Cyclone separators

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Experimental investigation on flash evaporation related to pipe leakage

Experimental investigation on flash evaporation related to p...

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作者： Cai, Benan Zhang, Qi Weng, Yu Gu, Hongfang Wang, Haijun State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Pipelines such as the surge line and main pipe are easily subjected to thermal stratification and thermal fatigue as a result of the nonuniform temperature distribution in the nuclear power plants. When the surge line or main pipe subjected to thermal stratification and thermal fatigue keeps operating for long time, the pipe leakage may happen due to the existence of pipeline crack. When the fluids with high temperature and pressure leak in the crack, the water will evaporate quickly, which means this process belongs to spray flash evaporation process. The flash evaporation related to pipe leak was experimentally studied in the paper. The experiment was carried out under high temperature and high pressure with low spray rate. The temperature and relative humidity (T&H) variations over time were monitored in the experiment with installing T&H detectors. The T&H variations at different measurement positions and with different spray rates were analyzed, respectively. In addition, the effect of the dimensionless parameters including the Weber number and Jakob number was also investigated. Results indicated that the response speed increased with the increase of the spray {1. rate. Higher Weber number and higher Jakob number led to higher evaporation rate. The slight pipe leakage can be predicted by using the (T&H) in the hazardous areas. Copyright © 2020 by ASME

关键词： Nuclear fuels

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