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Effects of temperature on drag reduction in a subsonic turbulent boundary layer via micro-blowing array

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Chinese Journal of Aeronautics 2022年第9期35卷 174-193页

作者： Lan XIE Binghua LI Yang ZHANG Yao zheng jianfeng ZOU Center for Engineering and Scientific Computation and School of Aeronautics and AstronauticsZhejiang UniversityHangzhou 310027China

A comparative study of two micro-blowing temperature cases has been performed to investigate the characteristics of drag reduction in a subsonic flat-plate flow(where the freestream Mach number is 0.7) by means of Direct Numerical Simulation(DNS). With minute amount of blowing gas injected from a 32 × 32 array of micro-holes arranged in a staggered pattern, the porosity of micro-holes is 23% and the blowing coefficient is 0.125%. The simulation results show that a drag reduction is achieved by micro-blowing, and a lower wall-friction drag can be obtained at a higher blowing temperature. The role of micro-blowing is to redistribute the total kinetic energy in the boundary layer, and the proportion of stream-wise kinetic energy decreases, resulting in the thickened boundary layer. Increasing micro-blowing temperature can accelerate this process and obtain an enhanced drag reduction. Moreover, an explanation of drag reduction by microblowing related to the micro-jet vortex clusters is proposed that these micro-jet vortex clusters firmly attached to the wall constitute a stable barrier, which is to prevent the direct contact between the stream-wise vortex and the wall. By Dynamic Mode Decomposition(DMD) from temporal/spatial aspects, it is revealed that small structures in the near-wall region play vital role in the change of turbulent scales. The high-frequency patterns are clearly strengthened, and the lowfrequency patterns just maintain but are lifted up.

关键词： Drag reduction Dynamic mode decomposition Micro-blowing Turbulent boundary layer Vortex

Diverse strategic approaches en route to Taxol total synthesis

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Chinese Chemical Letters 2022年第12期33卷 4957-4968页

作者： Zexian Li jianfeng zheng Wei-Dong Z.Li Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs School of Life Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Taxol is one of the most famous diterpenoid natural products used in clinical cancer therapy.Taxol and its analogues are popular synthetic targets and have attracted worldwide attention over the past decades.Tremendous research efforts have already been made and ten groups have achieved the total synthesis of Taxol since 1994.This mini-review summarized the recent highlights of divergent strategic approaches towards the chemical synthesis of Taxol's carbocyclic framework bearing a bridged eight-membered ring.

关键词： Taxol Total synthesis Biomimetic synthesis Linear strategy Convergent strategy

Family selection and evaluation of Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger based on stem analysis data at multiple sites

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林业研究:英文版 2023年第5期34卷 1627-1638页

作者： Conghui zheng jianfeng Dai Hongjing Zhang Yuzhong Wang Zhenhua Xu Zichun Du Hebei Technical Innovation Center for Forest Improved Variety Hebei Academy of Forestry and Grassland SciencesShijiazhuang 050061People’s Republic of China

Larix gmelinii var.principis-rupprechtii(Mayr.)Pilger is an important native tree species in North China with advantages of fast growth,straight trunk,and good wood properties.The multi-year and multi-site breeding research of families of the species has not been reported previously.Based on diameter at breast height(DBH),height and volume of 25 families on four experimental sites,we calculated variance components,genetic parameters,juvenile and mature trait correlations and made genotype main effect plus genotype×environment interaction effect(GGE)biplot based on the breeding values estimated using the method of best linear unbiased prediction(BLUP).Compared with height,DBH and volume had higher heritability and larger variation coefficients,making them the more suitable traits for family selection and evaluation.Based on these,GGE biplots containing 20 combinations of site×age were drawn using data at 13 to 17 years when the interactions between family and location were strong.Test sites classifications based on DBH,and volume were inconsistent,with two categories for DBH and one for volume.The Guyuan site was the most suitable with strong discriminating ability,high representativeness and stability among tree ages.Integrating the ranking results of DBH and volume,families 66,76,82 and 111 were high-yielding and stable,families 78 and96 were high-yielding with above average stability,families72 and 79 were high-yielding with below average stability,whereas stability of family 100 was inconsistent between DBH and volume.Early selection based on DBH was convenient and reliable,and can be made at seven years.This study provides support for the selection of Larix gmelinii var.principis-rupprechtii families in Hebei province and an example for the application of stem analysis data from multiple sites in tree breeding.

关键词： Larix gmelinii var principis-rupprechtii Stem analysis Multi-site Early selection Genotype main effect plus Genotype-environmental interaction effect(GGE)biplot

Reservoir geological modeling and significance of Cambrian Xiaoerblak Formation in Keping outcrop area, Tarim Basin, NW China

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Petroleum Exploration and Development 2020年第3期47卷 536-547页

作者： ZHENG Jianfeng PAN Wenqing SHEN Anjiang YUAN Wenfang HUANG Lili NI Xinfeng ZHU Yongjin Key Laboratory of Carbonate Reservoir CNPCHangzhou 310023China PetroChina Hangzhou Research Institute of Geology Hangzhou 310023China Tarim Oilfield Company PetroChinaKorla 841000China

Take the Cambrian Xiaoerblak Formation in the Keping(Kalpin) outcrop area as an example, a 28 km reservoir scale geological model was built based on description of 7 profiles, observation of more than 1000 thin sections, petrophysical analysis of 556 samples and many geochemical tests. The Xiaoerblak Formation, 158–178 m thick, is divided into three members and 5 submembers, and is composed of laminated microbialite dolomite(LMD), thrombolite dolomite(TD), foamy-stromatolite dolomite(FSD), oncolite dolomite(OD), grain dolomite(GD)/crystalline dolomite with grain ghost and micritic dolomite(MD)/argillaceous dolomite. The petrology features show that its sediment sequence is micro-organism layer – microbial mound/shoal – tidal flat in carbonate ramp background from bottom up. The reservoir has 5 types of pores, namely, framework pore, dissolved vug, intergranular and intragranular dissolved pore and intercrystalline dissolved pore, as main reservoir space. It is found that the development of pore has high lithofacies selectivity, FSD has the highest average porosity, TD, OD and GD come second. The reservoir is pore-vug reservoir with medium-high porosity and medium-low permeability. The dolomite of Xiaoerblak Formation was formed in para-syngenetic to early diagenetic stage through dolomitization caused by seawater. The reservoir development is jointly controlled by sedimentary facies, micro-organism type, high frequency sequence interface and early dolomitization. The classⅠand Ⅱ reservoirs, with an average thickness of 41.2 m and average reservoir-stratum ratio of about 25.6%, have significant potential. It is predicted that the microbial mounds and shoals in the middle ramp around the ancient uplift are the favorable zones for reservoir development.

关键词： Tarim Basin Keping area Xiaoerblak Formation dolomite microbialite reservoir genesis geological modeling

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Application of mapping and dating techniques in the study of ancient carbonate reservoirs: A case study of Sinian Qigebrak Formation in northwestern Tarim Basin, NW China

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Petroleum Exploration and Development 2020年第5期47卷 1001-1013页

作者： YANG Hanxuan HU Anping ZHENG Jianfeng LIANG Feng LUO Xianying FENG Yuexing SHEN Anjiang PetroChina Hangzhou Research Institute of Geology(HIPG) Hangzhou 310023China Key Laboratory of Carbonate Reservoirs CNPCHangzhou 310023China Radiogenic Isotope Facility School of Earth and Environmental SciencesThe University of QueenslandBrisbaneQLD 4072Australia

Ancient marine carbonates experienced complex modifications,making it difficult to identify reservoir genesis and effective porosity before hydrocarbon migration.To solve these issues,we used element mapping and carbonate mineral laser U-Pb radiometric dating techniques to study the diagenetic environments based on geochemistry and diagenesis-porosity evolution based on geochronology of the dolomite reservoir of the Sinian Qigebrak Formation,northwest Tarim Basin.Two major understandings were obtained as follows:(1)Supported by petrographic observations,the element mapping,stable isotopes,strontium isotope,and cathodoluminescence tests were performed on different phases of dolomite cements precipitated in vugs and dissolved fissures.The results show that the dolomite reservoirs of the Qigebrak Formation went through freshwater,marine,extremely shallow burial,burial and hydrothermal diagenetic environments after synsedimentary dolomitization;the reservoir spaces were mainly formed in the synsedimentary period(primary pores)and freshwater environment(supergene dissolution pores)before burial;whereas the marine,burial and hydrothermal environments caused the gradual filling of reservoir space by dolomite cements.(2)Based on the above understandings,each phase of dolomite cement precipitated in the reservoir space was dated by the U-Pb radiometric dating technique,and the diagenesis-porosity evolution curves constrained by geochronology were established.The loss of reservoir porosity mainly occurred in the early Caledonian,and during the peak period of hydrocarbon generation of Yuertusi Formation source rock,the reservoirs still maintained at a porosity of 6%?10%.The above understandings provide a certain basis for the evaluation of accumulation effectiveness of the Sinian Qigebrak Formation,northwestern Tarim Basin,and provide a case for the application of mapping and dating techniques in the study of ancient carbonate reservoirs.

关键词： U-Pb dating mapping Sinian Qigebrak Formation northwestern Tarim Basin diagenetic environment diagenesis-porosity evolution

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Mesh Adaptation for Curing the Pathological Behaviors of an Upwind Scheme

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Communications in Computational Physics 2022年第2期31卷 626-644页

作者： Yifan Xia Jianjing zheng jianfeng Zou Jifa Zhang Gaofeng Wang Yao zheng School of Aeronautics and Astronautics Zhejiang UniversityHangzhou 310027P.R.China Center for Hypergravity Experimental and Interdisciplinary Research Zhejiang UniversityHangzhou 310027P.R.China

In present paper,mesh adaptation is applied for curing the pathological behaviors of the enhanced time-accurate upwind scheme(Loh&Jorgenson,AIAAJ 2016).In the original ETAU(enhanced time-accurate upwind)scheme,a multidimensional dissipation model is required to cure the pathological behaviors.The multi-dimensional dissipation model will increase the global dissipation level reducing numerical resolution.In present work,the metric-based mesh adaptation strategy provides an alternative way to cure the pathological behaviors of the shock capturing.The Hessian matrix of flow variables is applied to construct the metric,which represents the curvature of the physical solution.The adapting operation can well refine the anisotropic meshes at the location with large gradients.The numerical results show that the adaptation of mesh provides a possible way to cure the pathological behaviors of upwind schemes.

关键词： Metric tensor mesh adaptation finite volume scheme unstructured grid

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 15-39页

作者： Changhui Liu Jing Wang Binghai Zhou Jianbo Yu Ying zheng jianfeng Liu School of Mechanical Engineering Tongji UniversityShanghai 201804China Shanghai Jiaotong University Shanghai 200240China Shanghai Waigaoqiao Shipbuilding Co. Ltd.Shanghai 200137China

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

关键词： Thin-walled parts Assembly quality Fixture layout optimization Modeling methods Optimization algorithms

Chemical, microstructure, and mechanical property of TiAl alloys produced by high-power direct laser deposition

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Journal of Materials Science & Technology 2022年第22期117卷 99-108页

作者： Xinyu Zhang Chuanwei Li Mengyao zheng Xudong Yang Zhenhua Ye jianfeng Gu Institute of Materials Modification and Modeling School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Materials Genome Initiative Center Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Key Laboratory of Materials Laser Processing and Modification Shanghai Jiao Tong UniversityShanghai 200240China

Additive manufactured metals sometimes exhibit extraordinary microstructures and mechanical properties due to the particular processes. In this paper, we focus on a novel gradient TiAl alloys fabricated byhigh-power direct laser deposition, whose chemical composition, microstructure, and mechanical property vary along the building direction. The results indicate that Al concentration dramatically decreasesfrom 39.5 at.% to 30.1 at.% as the height increases from the bottom to the top. Meanwhile, microstructural characterization indicates that the specimen appears basket-weave microstructure at the bottom,then the α_(2) and γ phase gradually decrease, and eventually it transforms into acicular martensite microstructure in the top region. The indentation analysis shows that the associated hardness increases asthe height increases, while the plasticity reaches a minimum value in the middle region. The increasingamount of β_(o)(ω) is considered to be responsible for the increasing hardness because of the strong precipitation strengthening effect. The high plasticity in the bottom and top regions results from the strongdeformation behaviors of the γ and β_(o) phases.

关键词： Direct laser deposition TiAl alloys Inhomogeneity Microstructure Mechanical properties

Effects of light intensity and photoperiod on runner plant propagation of hydroponic strawberry transplants under LED lighting

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International Journal of Agricultural and Biological Engineering 2019年第6期12卷 26-31页

作者： jianfeng zheng Dongxian He Fang Ji Key Laboratory of Agricultural Engineering in Structure and Environment of Ministry of Agriculture and Rural Affairs College of Water Resources and Civil EngineeringChina Agricultural UniversityBeijing 100083China

Vegetative propagation of strawberry(Fragaria×ananassa Duch.)in the plant factory with artificial lighting is considered as an effective approach to produce high-quality transplants.In this study,mother plants of‘Benihoppe’strawberry were grown hydroponically for 50 d under eight LED lighting treatments by combining four levels of light intensity(200,250,300 and 350mmol/(m^(2)·s))and two photoperiods(12 h/d and 16 h/d).Runner development,growth of runner plants,photon yield and energy yield in runners and runner plants were investigated to evaluate the strawberry propagation efficiency.Results indicated that length of runners decreased linearly with increasing daily light integral(DLI)under each photoperiod and was significantly shorter under photoperiod of 16 h/d.Runner elongation was inhibited by high DLI.Number of runners and runner plants formed by mother plants increased by 38.9%and 33.7%,when DLI increased from 8.6 to 11.5 mol/(m^(2)·d),respectively;however,no further increase was observed when DLI was higher than 11.5 mol/(m^(2)·d).Similar trends were found in crown diameter and biomass of primary and secondary runner plants.Negative impact of high DLI(20.2 mol/(m^(2)·d))on photosynthetic capacity of runner plants was observed as a decrease in leaf net photosynthetic rate,potential maximum photochemical efficiency of PSII,and chlorophyll content.Furthermore,photon yield and energy yield in runners and runner plants decreased significantly with increasing DLI.Therefore,DLI in a range of 11.5-17.3 mol/(m^(2)·d)is beneficial to improve strawberry propagation efficiency and quality of runner plants,and 11.5 mol/(m^(2)·d)is optimal for the strawberry propagation of runner plants in the LED plant factory because of the higher photon and energy yields.

关键词： hydroponic strawberry vegetative propagation daily light integral photon yield