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Journal of Hydrodynamics 2023年第6期35卷 1168-1178页

作者： Yan-hong Mao Hou-lin Liu Yong Wang Jie Chen Fei Liu Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang212013China Suzhou Vocational Institute of Industrial Technology Suzhou215104China

Cavitation commonly induces performance deterioration and system vibration in many engineering applications.This paper aims to investigate the effects of air injection on cavitation evolution,pressure pulsation and vibration in a centrifugal pump with inducer.In this paper,the high-speed camera is used to capture the gas flow pattern and cavitation evolution process in the inducer.The impacts of air injection on the inlet pressure pulsation and vibration are also investigated.The results show that the cavitation development in the inducer undergoes four patterns:incipient cavitation,sheet cavitation,cloud cavitation and super cavitation.During the development of cavitation,the main frequency of the pressure pulsation shifts to lower frequencies,and the amplitude of the vibration increases.In addition,air injection promotes the incipient cavitation but delays the cavitation development.A small amount of air can effectively decrease amplitudes of pressure pulsation and vibration.But as the air content increases,the fluctuations and amplitudes of pressure pulsation and vibration increase.

关键词： air injection cavitation control inducer vibration pressure pulsation

The effects of step inclination and air injection on the water flow in a stepped spillway:A numerical study

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Journal of Hydrodynamics 2017年第2期29卷 322-331页

作者： Khadidja Kherbache Xavier Chesneau Belkacem Zeghmati Stéphane Abide Saadia Benmamar Universite de Perpignan Via Domitia(UPVD) LAhoratoire the Mathematiques et de PhySique(LAMPS)EA4217F-66860PerpignanFrance Ecole Nationale Polytechnique Laboratoire de Recherche des Sciences de I'eau10 Avenue Hassen Badi16000 AlgerAlgerie

In this work, we perform a numerical study of a water flow over a stepped spillway. This flow is described by the Reynolds averaged Navier-Stokes equation （RANS） associated with the turbulence k - model. These equations are solved using a commercial software based on the finite volume scheme and an unstructured mesh. The air-water flow was modeled using volume of fluid （VOF） and multiphasic methods. The characteristics of the profile, etc.. We analyze the effects on the flow structure of the flow were investigated including the total pressure, the velocity steps and countermarch inclination, the air injection through the countermarch into the water flow and the dynamics water discharges. Results show that the inclination of the countermarch relative to the vertical and the air injection into the water flow increase the total pressure in the neighbourhood of the steps.

关键词： Stepped spillway turbulence air-water air injection volume of fluid （VOF） method multiphasic method

Influence of Endwall air injection with Discrete Holes on Corner Separation of a Compressor Cascade

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Journal of Thermal Science 2021年第5期30卷 1684-1704页

作者： CAO Zhiyuan GAO Xi ZHANG Xiang ZHANG Fei LIU Bo School of Power and Energy Northwestern Polytechnical UniversityXi’an710072China

The aim of this study is to reveal the influence mechanism of endwall air injection with distributed holes on the corner separation of a highly loaded compressor cascade,so as to promote the application of injection in aero-engines.Single-hole and double-hole endwall injection schemes featuring different axial locations,pitchwise locations,injection mass rates and injection directions,were designed and investigated.Results showed that the corner separation was eliminated by endwall injection;the optimal single-hole injection scheme achieved an endwall loss coefficient reduction of 29.7%,with injection coefficient as low as 0.48%.The optimal axial location of single-hole endwall injection was at 82%axial chord,being the center of corner separation.However,as injection hole was located at upstream of it,endwall injection resulted in severer corner separation.The mid-span flow field was deteriorated after endwall injection,which was due to 3D flow effects,i.e.,AVDR(axial velocity density ratio)effect and low-momentum fluid spanwise migration effect.The optimal injection was achieved at low injection angle and from close to the suction surface on pitchwise.Double-hole injection exhibited inferior performance compared with single-hole,which was due to the interaction of the two injection streams and mixing of injection streams with the bulk stream.

关键词： compressor cascade corner separation flow control air injection endwall discrete hole injection

Combustion enhancement in rearward step based scramjet combustor by air injection at step base

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Propulsion and Power Research 2021年第3期10卷 224-234页

作者： Amit Thakur Nishanth Thillai Amritesh Sinha Mechanical Engineering PES UniversityIndia Institute for Aerospace Studies University of TorontoCanada Aerodynamics Energetics and PropulsionISAE SupaeroFrance

Numerical simulations were performed to model the non-reacting and reacting flow behind a rearward step flameholder in Mach 1.6 supersonic flow with fuel injection at the step base.The combustor geometry was based on the University of Florida scramjet experimental facility.Turbulence was modeled using k-u shear stress transport(SST),laminar flamelet was used for combustion modeling.Wall static pressure showed good agreement with experimental data for non-reacting and reacting flow.For non-reacting flow,dummy fuel helium mole fraction distribution in the recirculation region behind the step was validated with planar laser induced fluorescence(PLIF)images in experiments.To improve the combustion characteristics,air was injected in tandem with hydrogen at step base using various configurations.With all fuel injection as baseline,the case with 2 air jets around each fuel jet and air injected at 2 times the stagnation pressure of fuel showed the most improvement compared to other cases.It was most effective in reducing the local fuel richness,shortening the flame length and increasing combustion efficiency.

关键词： Step flameholder Scramjet combustor Local equivalence ratio air injection Combustion efficiency

Simulation study of huff-n-puff air injection for enhanced oil recovery in shale oil reservoirs

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Petroleum 2018年第1期4卷 7-14页

作者： Hu Jia James J.Sheng State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengduSichuan 610500China Bob L.Herd Department of Petroleum Engineering Texas Tech UniversityLubbockTX 79409USA

This paper is the first attempt to evaluate huff-n-puff air injection in a shale oil reservoir using a simulation approach.Recovery mechanisms and physical processes of huff-n-puff air injection in a shale oil reservoir are investigated through investigating production performance,thermal behavior,reservoir pressure and fluid saturation features.air flooding is used as the basic case for a comparative study.The simulation study suggests that thermal drive is the main recovery mechanism for huff-n-puff air injection in the shale oil reservoir,but not for simple air flooding.The synergic recovery mechanism of air flooding in conventional light oil reservoirs can be replicated in shale oil reservoirs by using air huff-npuff injection strategy.Reducing huff-n-puff time is better for performing the synergic recovery mechanism of air injection.O2 diffusion plays an important role in huff-n-puff air injection in shale oil reservoirs.Pressure transmissibility as well as reservoir pressure maintenance ability in huff-n-puff air injection is more pronounced than the simple air flooding after primary depletion stage.No obvious gas override is exhibited in both air flooding and air huff-n-puff injection scenarios in shale reservoirs.Huffn-puff air injection has great potential to develop shale oil reservoirs.The results from this work may stimulate further investigations.

关键词： air injection huff-n-puff Shale reservoirs Unconventional air flooding Enhanced oil recovery

Effect of reservoir heterogeneity on air injection performance in a light oil reservoir

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Petroleum 2018年第1期4卷 15-24页

作者： Hu Jia State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500China

air injection is a good option to development light oil reservoir.As well-known that,reservoir heterogeneity has great effect for various EOR processes.This also applies to air injection.However,oil recovery mechanisms and physical processes for air injection in heterogeneous reservoir with dip angle are still not well understood.The reported setting of reservoir heterogeneous for physical model or simulation model of air injection only simply uses different-layer permeability of porous media.In practice,reservoir heterogeneity follows the principle of geostatistics.How much of contrast in permeability actually challenges the air injection in light oil reservoir?This should be investigated by using layered porous medial settings of the classical Dykstra-Parsons style.Unfortunately,there has been no work addressing this issue for air injection in light oil reservoir.In this paper,Reservoir heterogeneity is quantified based on the use of different reservoir permeability distribution according to classical Dykstra-Parsons coefficients method.The aim of this work is to investigate the effect of reservoir heterogeneity on physical process and production performance of air injection in light oil reservoir through numerical reservoir simulation approach.The basic model is calibrated based on previous study.Total eleven pseudo compounders are included in this model and ten complexity of reactions are proposed to achieve the reaction scheme.Results show that oil recovery factor is decreased with the increasing of reservoir heterogeneity both for air and N2 injection from updip location,which is against the working behavior of air injection from updip location.Reservoir heterogeneity sometimes can act as positive effect to improve sweep efficiency as well as enhance production performance for air injection.High O2 content air injection can benefit oil recovery factor,also lead to early O2 breakthrough in heterogeneous reservoir.Well-type does not show great effect on production performance for air injection in extreme hete

关键词： air injection Light oil Heterogeneity Dykstra-parsons coefficients Enhanced oil recovery Recovery mechanism

ALKALINE PRETREATMENT AND air MIXING FOR IMPROVEMENT OF METHANE PRODUCTION FROM ANAEROBIC CO-DIGESTION OF POULTRY LITTER WITH WHEAT STRAW

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Frontiers of Agricultural Science and Engineering 2023年第3期10卷 424-436页

作者： Yuanhang ZHAN Jun ZHU Yiting XIAO Leland C.SCHRADER Department of Biological and Agricultural Engineering University of ArkansasFayettevilleAR 72701USA

Alkaline pretreatment(AL)and air mixing(air)both have the potential to improve anaerobic co-digestion(Co-AD)of poultry litter with wheat straw for methane production.In this study,the effects of the combination of AL(pH 12 for 12 h)and air mixing(12 mL·d^(−1))on the Co-AD process were investigated.The substrate hydrolysis was enhanced by AL,with soluble chemical oxygen demand increased by 4.59 times and volatile fatty acids increased by 5.04 times.The cumulative methane yield in the group of Co-AD by AL integrated with air(Co-(AL+air)),being 287 mL·(g VS_(added))^(−1),was improved by 46.7%compared to the control.The cone model was found the best in simulating the methane yield kinetics with R^(2)≥0.9979 and root mean square prediction error(rMSPE)≤3.50.Co-(AL+air)had a larger hydrolysis constant k(0.14 d^(−1))and a shorter lag phaseλ(0.99 d)than the control(k=0.12 d^(−1),λ=2.06 d).The digestate improved the removal of total solids and total volatile solids by 2.0 and 2.3 times,respectively.AL facilitated substrate degradation,while air can enrich the microbial activity,together enhancing the methane generation.The results show that AL+air can be applied as an effective method to improve methane production from the Co-AD process.

关键词： sodium hydroxide air injection cumulative methane yield kinetic modeling analysis digestate

Resistance of air injection Transportation in a Cutter-suction Dredger

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International Journal of Plant Engineering and Management 2010年第4期15卷 193-199页

作者： XIONG Ting FAN Shi-dong YANG Zi-xuan School of Energy and Power Engineering Wuhan University of Technology Wuhan 430063 P. R. China

Cutter-suction dredger transports slurry through pipeline. But the pipeline is easy to be jammed and frayed because of huge resistance, resulting in limited exertion of dredger and high energy consumption. One of the solutions is air injection transporting, which can reduce the resistance in pipeline. This paper makes research on the relations between pipeline distance and other factors such as slurry concentration, pressure of air injection and transportation distance, by making use of Prof. Aluf Orell＇ s slug model. The test data prove that the key factors are slurry concentration and air volume fraction, and that high slurry concentration and low air volume fraction can reduce more resistance, and such reducing effect becomes weaker with the increase of transportation distance.

关键词： cutter-suction dredger air injection resistance reducing slug model

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吹气比对外凸曲壁湍流再层流化现象的影响

Acta Mechanica Sinica 2022年第5期38卷 61-71,I0002页

作者：苏纬仪张风睿王谋远 College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

再层流化是一种边界层加速时湍流向层流或类层流反向转捩的流动现象,它能降低边界层抵抗逆压梯度的能力.为了揭示主动射流方法调控湍流再层流化现象的机理,本文采用大涡模拟方法,研究了不同吹气比对马赫3超声速湍流绕外凸曲壁膨胀加速... 详细信息

再层流化是一种边界层加速时湍流向层流或类层流反向转捩的流动现象,它能降低边界层抵抗逆压梯度的能力.为了揭示主动射流方法调控湍流再层流化现象的机理,本文采用大涡模拟方法,研究了不同吹气比对马赫3超声速湍流绕外凸曲壁膨胀加速时再层流化现象的影响.结果表明,无控制时,膨胀加速显著降低了大尺度拟序结构和湍动能等湍流特征.施加主动射流控制后,再层流化现象被有效抑制.同时,研究还发现,吹气比在湍流再层流化流动控制中起到重要作用.在相同的射流动量比和静压比条件下,吹气比越大,主动射流抑制再层流化现象的效果越明显.

关键词： Relaminarization air injection Supersonic turbulence