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Research into Configuration and Flow of Wall Oil Film in Bearing Chamber Based on droplet size Distribution

Chinese Journal of Aeronautics 2011年第3期24卷 355-362页

作者： CHEN Guoding SUN Hengchao WANG Jun School of Mechanical Engineering Northwestern Polytechnical University Xi 'an 710072 China AVIC Commercial Aircraft Engine Co. Ltd Shanghai 200030 China

The lubrication design and heat transfer determination of bearing chambers in aeroengine require a sufficient understanding of the oil droplet-film interaction and physical characteristic in an oil/air two-phase flow state. The analyses of oil droplet movement, mass and momentum transfer during the impingement of droplet/wall, as well as wall oil film thickness and flow velocity are very important for the bearing chamber lubrication and heat transfer calculation. An integrated model in combination with droplet movement, droplet/wall impact and film flow analysis is put forward initially based on the consideration of droplet size distribution. The model makes a contribution to provide more practical and feasible technical approach, which is not only for the study of droplet-film interaction and physical behavior in bearing chambers with oil/air two-phase flow phenomena, but also useful for an insight into the essence of physical course through droplet movement and deposition, film formation and flow. The influences of chamber geometries and operating conditions on droplet deposition mass and momentum transfer, and wall film thickness and velocity distribution are discussed. The feasibility of the method by theoretical analysis is also verified by the ex- isting experimental data. The current work is conducive to expose the physical behavior of wall oil film configuration and flow in bearing chamber, and also significant for bearing chamber lubrication and heat transfer study under oil/air two-phase flow conditions.

关键词： bearing chamber droplet size film thickness oil/air two-phase aeroengine lubrication

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Effect of droplet size on the jet breakup characteristics of n-butanol during impact on a heated surface

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Journal of Traffic and Transportation Engineering(English Edition) 2020年第3期7卷 320-330页

作者： Han Wu Longmin Tang Chunze Cen Chia-Fon Lee School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Department of Mechanical Aerospace and Ciuil EngineeringUniversity of ManchesterManchester M139PLUK Department of Mechanical Science and Engineering University of Illinois at Urbana-ChampaignUrbana1L 61801USA

Jet breakup during droplet impacted on heated surface has received wide concerns due to its *** Weber number(We)is a common used dimensionless parameter to classify and analyze the phenomenon,but it is unable to summarize all detailed phenomenon variations and related ***,the effect of droplet size on jet breakup was investigated by considering its significant difference in various *** behavior of n-butanol droplets with diameter range from 1.71 mm to 2.84 mm impacts a heated surface with jet breakup was recorded by backlit *** parameters,the jet breakup time,the jet breakup length and the jet ligament diameter,were analyzed to illustrate the *** results showed that these parameters are affected by the droplet size largely at 10droplet diameter reduces with Weber number for all initial size droplets while the larger initial droplet corresponds to larger *** breakup time,breakup length and jet ligament diameter increase with the initial *** time of jet breakup versus agrees well with the theory of Rayleigh instability regardless of droplet *** addition,the jet breakup phenomenon was observed to evolve into pancake bouncing with an ultrafine high-speed jet when the We was above 50.

关键词： Energy engineering droplet impact Heated surface droplet size Jet breakup n-butanol

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droplet size and spray pattern characteristics of PWM-based continuously variable spray

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International Journal of Agricultural and Biological Engineering 2009年第1期2卷 8-18页

作者： Deng Wei He Xiongkui Ding Weimin College of Science China Agricultural UniversityBeijing 100193China College of Engineering Nanjing Agricultural UniversityNanjing 210031China

A Pulse-Width-Modulation-based(PWM-based)continuously variable sprayer was developed using a proportional regulating solenoid *** flow-rate was obtained by varying the duty cycle of the actuating signal with 24 kHz ***-rate regulating ranges of the PWM-based continuously variable spray(*** turndown ratio responding to 100%-40%duty cycle)are 7.14:1,3.57:1,and 3.70:1 for flat-fan,hollow-cone and solid-cone nozzles,*** purpose of the study was to evaluate the PWM-based continuously variable *** method was to quantify the effects of flow-rate control on spray characteristics in terms of droplet size spectra,spray distribution patterns,and spray angle for flat-fan,hollow-cone,solid-cone *** all nozzles tested,spray distribution concentrated on the center of the spray field with the decrease of *** the spray shape is still *** sensitivities of the spray angles to flow-rate were 0.83,0.67,and 0.58(o)/%respectively for flat-fan,hollow-cone and solid-cone *** with the sensitivities of spray angle for PWM-based intermittent variable spray,they are somewhat *** flow-rate was reduced from the maximum(100%flow-rate)to the minimum controllable rate,the observed median diameter of spray droplets decreased by 5.4%,9.8%,and 9.9%for flat-fan,hollow-cone and solid-cone nozzles,*** indicates that spray droplet size was affected slightly by flow-rate control.

关键词： Pulse Width Modulation(PWM) continuously variable spray droplet size spray distribution pattern spray angle

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Effects of droplet size and spray volume parameters on droplet deposition of wheat herbicide application by using UAV

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International Journal of Agricultural and Biological Engineering 2021年第1期14卷 74-81页

作者： Changfeng Shan Guobin Wang Haihong Wang Yingjie Xie Huizheng Wang Shilong Wang Shengde Chen Yubin Lan College of Agricultural Engineering and Food Science Shandong University of TechnologyShandong Provincial Engineering Technology Research Center for Agricultural Aviation Intelligent EquipmentZibo 255022ShandongChina Corteva Agroscience Technology(Shanghai)Co. LtdShanghai 201203China Zibo Agricultural and Rural Service Center Zibo 255022ShandongChina National Center for International Collaboration Research on Precision Agricultural Aviation Pesticides Spraying Technology(NPAAC) Ministry of Science and TechnologyCollege of Electronics EngineeringSouth China Agricultural UniversityGuangzhou 510642China Department of Biological and Agricultural Engineering Texas A&M UniversityCollege StationTX 77845USA

With the characteristic of flexible and precise,unmanned aerial vehicles(UAVs)for low volume applications are increasing substantially and quickly around the ***,little attention has been paid to the study of wheat herbicides with UAV,especially the research on the spray volume and droplet size of the herbicide sprayed by *** objectives of this study were to compare the droplet deposition from a typical commercial UAV under four different spray volumes of 7.5 L/hm2,15.0 L/hm2,22.5 L/hm2,and 30.0 L/hm2 and three different volume median diameter(VMD)of 150μm,200μm,and 300μm during winter wheat weeding *** software was used to analyze droplet deposition parameters including the percentage of spray coverage and the number of droplets in various sampling *** test results showed that the droplet deposition waseffected by each factor *** the spray volume was 7.5 L/hm2,the effect of VMD on the percentage of spray coverage was not ***,these variation rules were changed to smaller droplets with greater coverage when the spray volume higher than 15.0 L/*** all treatments,the number of droplets increased with decreasing VMD or increasing spray *** maximum percentage of spray coverage and the number of droplets that were achieved under the VMD of 150μm and the spray volume of 30.0 L/hm2 were 12.8%and 40.0 droplets/cm2,*** variation coefficients of the percentage of spray coverage and the number of droplets were 29.0%-73.3%and 20.2%-54.1%,*** most uniform deposition was achieved under the spray volume of 15.0 L/hm2and the VMD of 150μ*** results revealed the effect of droplet size and spray volume parameters on droplet deposition,which was useful for guiding farmers on how to use UAVs for weeding in winter wheat fields.

关键词： unmanned aerial vehicle spray volume droplet size droplet deposition

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Development and droplet size characteristics of wall impinging diesel fuel spray at high injection pressure

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Progress in Natural Science:Materials International 1997年第5期 97-105页

作者：龚允怡李理光黄叶舟 China National Engine Combustion Laboratory Tianjin 300072 Tianjin University

The characteristics of droplet size and concentration distribution of diesel spray with wall impingement at high injection pressure have been studied experimentally. Two nozzles with different hole diameters in a fuel supply system that consists of pump, pipe and nozzle have been researched. The experiment was carried out under the condition that the air density is similar to that in the engine cylinder. The spray impinges to a flat plate vertically. The temperature of the plate surface is variable. The droplet size was measured by a Malvern particle sizer based on the principle of laser diffraction. When the spray impinges on a room-temperature wall, much of the fuel will accumulate on the wall surface. While in the space over the wall, the smaller the nozzle hole, the smaller the SMD and the droplet density. When the wall temperature is high enough, the droplet of the impinging spray will be rebounded and evaporated. The optimum surface temperature for rebounding and evaporating is about 573 K.

关键词： diesel fuel spray droplet size wall impinging high injection pressure.

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Effect of Nozzle Orientation on droplet size and droplet Velocity from Vineyard Sprays

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Journal of Agricultural Science and Technology(B) 2015年第10期5卷 672-678页

作者： Ariane Vallet Cyril Tinet Jean-Paul Douzals Research Institute in Science and Technology for Environment and Agriculture (IRSTEA) Unite Mixte de Recherche lnJbrmation andTechnologies for Agro-Processes BP 5095 F-34196 Montpellier Cedex 5 France

Spray drift has become an important issue in pesticide application. Vineyard spraying is particularly interesting to consider, as pesticide droplets are not directed towards the ground but rather towards the targeted crop. The aim of this study was to investigate the influence of nozzle orientation on droplet size and droplet velocity using three different nozzles （IDK, TVI and TXA） used in vineyards. Two series of measurement were performed in order to assess the effect of the gravity on sprays. droplet size and one-dimensional droplet velocity characteristics were measured using a phase Doppler particle analyser （PDPA）. Two planes, i.e., one horizontal and one vertical, were considered. Results suggest that the nozzle orientation slightly affects the size distribution, which is shifted towards larger droplets when nozzles spray horizontally compared to vertically spray, However, droplet axial velocity distribution is shifted towards lower values. Supposing that the only droplets which can reach the crop are those with an axial velocity greater than 1 m/s and a diameter larger than 100 lain, results showed significant differences according to the nozzle and orientation. More than 98.6% of the spray volume would reach the target whatever the orientation of the IDK nozzle, 78.8% of the spray volume would reach the crop when the TVI nozzle sprays horizontally, while only 16.0% of the spray volume would reach the crop when TXA nozzle sprays horizontally. This paper offers new perspectives in the comprehension and the optimization of the deposition process into the vegetation based from droplet size and velocity profiles from horizontally oriented sprays from flat fan or hollow cone nozzles.

关键词： droplet size droplet velocity nozzle orientation vineyard sprays.

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Effect of Velocity Ratio,Viscosity Ratio,Contact Angle,and Channel size Ratio on droplet Formation

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Fluid Dynamics & Materials Processing 2023年第10期19卷 2471-2480页

作者： Mohammed Bourega Ibrahim Kromba Khadidja Feah Arbi Soﬁane Souimane Biomedical Engineering Laboratory Abu Bakr Belkaid UniversityTlemcen13000Algeria

This study uses a T-junction to examine the effects of different parameters(velocity ratio,viscosity,contact angle,and channel size ratio)on the generation of microdroplets,related rate,and *** speciﬁcally,numerical simulations are exploited to investigate situations with a velocity varying from 0.004 to 1.6 m/s for the continuous phase and from 0.004 to 0.8 m/s for the dispersed phase,viscosity ratios(0.668,1,6.689,10,66.899),contact angle 80°size ratios(1,1.5,2 and 4).The results show that canal size inﬂuences droplet size and the generation *** contact angle has an impact on the form and the quality of generated ***,the relationship between velocity and viscosity ratios,droplet size,and generation rate is non-monotonic.

关键词： Microﬂuidics T-junction droplet generator droplet size droplet diameter generation rate

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Effects of piperacillin synthesis on the infterfacial tensions and droplet sizes

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Chinese Journal of Chemical Engineering 2021年第10期34卷 53-62页

作者： Yu Xie Guoming Huang Weiguo Hu Yujun Wang The State Key Laboratory of Chemical Engineering Department of Chemical EngineeringTsinghua UniversityBeijing 100084China North China Pharmaceutical Group Co. Ltd.Shijiazhuang 052165China

Piperacillin is a polar organic substance,and can reduce the interfacial tension of oil and water when dissolved in *** this study,changes in dichloromethane–water interfacial tensions and microdroplet sizes during piperacillin synthesis from an aqueous solution of ampicillin and dichloromethane solution of 4-ethyl-2,3-dioxo-1-piperazine carbonyl chloride(EDPC)were observed using a pendent drop technique and a coaxial ring tube system with embedded high-speed camera,*** was found that the rapid N-acylation reaction caused the piperacillin at the interface to synthesize rapidly and diffuse out slowly,resulting in the interfacial tension decreased from 19.5 m N·m-1 to 7.2 m N·m-1 rapidly and then increased slowly as the concentrations of ampicillin and EDPC were 0.05 mol·L-1 and 0.1 mol·***,the increase in the concentration of EDPC increased the peak concentration of piperacillin at the interface,and the addition of ethyl acetate to the ampicillin solution promoted mass transfer and reduced the aggregation of piperacillin *** synthesis,the interfacial tension decreased,leading to a change in droplet sizes in the micro-reaction *** two-phase reaction was carried out in a coaxial ring tube,with ampicillin and EDPC solutions as continuous and dispersed phases,*** reaction reduced the dripping flow area,and the addition of ethyl acetate to the ampicillin solution slightly affected the division of the flow *** the same flow conditions,the droplet sizes of the reaction group were smaller than those of the no reaction *** experimental results demonstrated that the increase of the continuous phase,decrease in the dispersed phase flow rate,or increase in EDPC concentration making droplet sizes smaller,and the addition of ethyl acetate slightly affected droplet *** findings are important for the design and optimization of piperacillin synthesis reactors.

关键词： Pendant drop Interfacial tension Microchannel droplet size Piperacillin synthesis Mass transfer

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Destabilising persistent coal froth using silicone oil

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International Journal of Mining Science and Technology 2021年第6期31卷 1023-1031页

作者： Shiqi Liu Xumeng Chen Yongjun Peng School of Chemical Engineering The University of QueenslandBrisbaneQLD 4072Australia

Persistent froth is becoming more and more common in coal and mineral flotation plants and presents safety and operational *** effective method has been developed to destabilise persistent *** a new initiative,this study examined the structural difference between persistent foam and coal froth,based on which a solution was developed to maximumly destabilise coal *** test,oscillatory rheology measurement and scanning electron microscopy(SEM) analysis indicated that the coal froth was more stable than the foam due to the formation of thin capillaries and tightly arranged coal particles on bubble *** 107 μm silicone oil droplet could completely destabilise the foam at 2 mmol/L concentration,it only destabilised less than 50% coal froth even at 6 mmol/L *** maximumly destabilise the coal froth formed by-38 and-20 μm particles,24 and 18 μm silicone oil droplets were required to pass through the thin capillaries and enter the bubble films,***,smaller silicone oil droplets could not bridge the bubble films to destabilise coal froth and therefore a critical droplet size occurred depending on the size of particles stabilising the froth.

关键词： Persistent froth Destabilisation Silicone oil droplet size Oscillatory rheology

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Spray and mixing characteristics of liquid jet in a tubular gas-liquid atomization mixer

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Chinese Journal of Chemical Engineering 2021年第6期34卷 1-11页

作者： Lingzhen Kong Jiaqing Chen Tian Lan Huan Sun Kuisheng Wang School of Mechanical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Beijing Key Laboratory of Pipeline Critical Technology and Equipment for DeepWater Oil&Gas Development Beijing 102617China College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China

For the design and optimization of a tubular gas-liquid atomization mixer,the atomization and mixing characteristics of liquid jet breakup in the limited tube space is a key *** this study,the primary breakup process of liquid jet columnwas analyzed by high-speed camera,then the droplet size and velocity distribution of atomized droplets were measured by Phase-Doppler anemometry(PDA).The hydrodynamic characteristics of gas flow in tubular gas-liquid atomization mixer were analyzed by computational fluid dynamics(CFD)numerical *** results indicate that the liquid flow rate has little effect on the atomization droplet size and atomization pressure drop,and the gas flowrate is themain influence *** all experimental gas flowconditions,the liquid jet column undergoes a primary breakup process,forming larger liquid blocks and *** the gas flow rate(Qg)is less than 127 m^(3)·h^(−1),the secondary breakup of large liquid blocks and droplets does not occur in venturi throat *** Sauter mean diameter(SMD)of droplets measured at the outlet is more than 140μm,and the distribution is *** Qg>127 m^(3)·h^(−1),the large liquid blocks and droplets have secondary breakup process at the throat *** SMD of droplets measured at the outlet is less than 140μm,and the distribution is *** 127droplets is bag breakup or pouch *** 181droplets is shear breakup or catastrophic *** order to ensure efficient atomization and mixing,the throat gas velocity of the tubular atomization mixer should be designed to be about 51 m·s^(−1) under the lowest operating flow *** pressure drop of the tubular atomization mixer increases linearly with the square of gas velocity,and the resistance coefficient is about 2.55 in single-phase flow condition and 2.73 in gas-liquid atomization condition.

关键词： Atomization mixing Liquid jet Primary breakup droplet breakup droplet size

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