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Experimental study on shock interaction control of double wedge in high-enthalpy hypersonic flow subject to plasma synthetic jet

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Chinese journal of Aeronautics 2024年第4期37卷 151-165页

作者： Xuzhen xie Qiang LIU Yan ZHOU Zhenbing LUO Wei xie Guanghui BAI Kai LUO Qiu WANG jianjun WU College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China China Academy of Launch Vehicle Technology Beijing 100076China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China

The hypersonic shock-shock interaction flow field at double-wedge geometries controlled by plasma synthetic jet actuator is experimentally studied in a Ma = 8 high-enthalpy shock tunnel with the purpose of exploring a novel technique for reducing surface heat flux in a real flight environment. The results demonstrate that increasing the discharge energy is advantageous in eliminating the shock wave, shifting the shock wave interaction point, and shortening the control response time. The oblique shock wave can be completely removed when the actuator's discharge energy grows from 0.4 j to 11.5 j, and the displacement of the shock wave interaction point increases by 124.56%, while the controlled response time is shortened by 30 μs. Besides, the reduction in diameter of the jet exit is firstly proved to have a negative impact on energy deposition in a working environment with incoming flow, which reduces the discharge energy and hence decreases the control effect. The shock wave control response time lengthens when the jet exits away from the second wedge. Along with comparing the change in wall heat flux at the second wedge over time, the control effect of plasma synthetic jet actuator with and without inflation is also analyzed. When plasma synthetic jet works in inflatable mode, both the ability to eliminate shock waves and the shifting effect of the shock wave interaction point are increased significantly, and the wall heat flux is also reduced.

关键词： Hypersonic flow High-enthalpy flow Plasma synthetic jet Shock wave Flow control

Effect of Ti and Ta content on the oxidation resistance of Co-Ni-based superalloys

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International journal of Minerals,Metallurgy and Materials 2024年第2期31卷 351-361页

作者： Yuheng Zhang Zixin Li Yunwei Gui Huadong Fu jianxin xie Beijing Advanced Innovation Center for Materials Genome Engineering University of Science and Technology BeijingBeijing 100083China Institute of Materials Intelligent Technology Liaoning Academy of MaterialsShenyang 110004China Key Laboratory for Advanced Materials Processing(MOE) University of Science and Technology BeijingBeijing 100083China Beijing Laboratory of Metallic Materials and Processing for Modern Transportation University of Science and Technology BeijingBeijing 100083China

Co-Ni-based superalloys are known for their capability to function at elevated temperatures and superior hot corrosion and thermal fatigue ***,these alloys show potential as crucial high-temperature structural materials for aeroengine and gas turbine hot-end *** previous work elucidated the influence of Ti and Ta on the high-temperature mechanical properties of ***,the intricate interaction among elements considerably affects the oxidation resistance of *** this paper,Co-35Ni-10Al-2W-5Cr-2Mo-1Nb-xTi-(5−x)Ta alloys(x=1,2,3,4)with varying Ti and Ta contents were designed and compounded,and their oxidation resistance was investigated at the temperature range from 800 to 1000℃.After oxidation at three test conditions,namely,800℃for 200 h,900℃for 200 h,and 1000℃for 50 h,the main structure of the oxide layer of the alloy consisted of spinel,Cr_(2)O_(3),and Al_(2)O_(3)from outside to *** consisting of Ta,W,and Mo formed below the Cr_(2)O_(3)*** interaction of Ti and Ta imparted the highest oxidation resistance to 3Ti2Ta ***,an excessive amount of Ti or Ta resulted in an adverse effect on the oxidation resistance of the *** study reports the volatilization of W and Mo oxides during the oxidation process of Co-Ni-based cast superalloys with a high Al content for the first time and explains the formation mechanism of holes in the oxide *** results provide a basis for gaining insights into the effects of the interaction of alloying elements on the oxidation resistance of the alloys they form.

关键词： Co-Ni-based superalloys high-temperature oxidation Ti and Ta elements formation mechanism of holes

Influence of Vanes and Blades on Ingress in Axial Rim Seal for Turbine Stages

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journal of Thermal Science 2024年第3期33卷 833-846页

作者： REN Ran DU Qiang LIU Guang ZENG Yanlian xie Lei Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China National Key Laboratory of Science and Technology on Advanced Light-duty Gas-turbine Beijing100190China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing100190China

Hot gas ingestion refers to the phenomenon of mainstream hot gas flowing into the space cavity of a turbine *** studies have found that mainstream annulus pressure distribution plays an important role in hot gas ingestion,but due to its complexity,the mechanism of the interaction between mainstream flow and hot gas ingestion remains *** paper adopts the URANS method,and three sealing flow rates are considered,named C_(w)=0,C_(w)=500,and C_(w)=*** time-averaged annulus pressure distribution shows that an increase in the sealing flow decreases the pressure value,and the effects of the sealing flow on the pressure distribution of the leading edge of the blade are much more influential than that of the trailing edge of the *** unsteady pressure time-space distribution in the annulus indicates that a time-space tilted distribution of pressure at the rim exits when the sealing flow *** phenomenon is mainly due to the strong feedback mechanism of the sealing flow to the annulus pressure field.A comparison of the pressure and mean radial velocity distribution of the mainstream shows that the ingestion mainly occurs on the blade side,where the pressure is lower than on the vane *** flow characteristics at the wheel rim are analyzed with a sealing flow rate C_(w)=5000,and under these conditions,both pressure-induced ingestion and ingestion caused by a passage vortex can be *** three-dimensional and inertial effects of the mainstream at the wheel rim lead to the generation of separation vortices on the blade side,and the presence of separation vortices leads to ingestion along the blade *** the same time,pressure on the blade side will cause the fluid to have a radial inward flow tendency,which will promote the formation of separation vortices,leading to more serious ingestion in the high-pressure region on the blade *** blade pressure field can be more significant than the vane trailing pressure field in the rim sea

关键词： separation vortex unsteady rim seal the effect of blade on ingestion

Giant low-field reversible magnetocaloric effect at liquid helium temperature of niobium and iron co-substituted EuTiO_(3) compounds

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journal of Rare Earths 2024年第4期42卷 710-715页

作者： Zhihong Hao Quanyi Liu Huicai xie Yan Zhang Zhaojun Mo School of Rare Earth and New Materials Engineering Ganzhou Innovation Center of Rare Earth Permanent Magnet Material Advanced Manufacturing and Intelligent Equipment TechnologyGannan University of Science and TechnologyGanzhou341000China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou34119China School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan030024China

Giant magnetocaloric effect(MCE)materials in the liquid helium temperature region have attracted a lot of attention in the field of low-temperature magnetic refrigeration(MR).In this study,a series of niobium(Nb)and iron(Fe)co-substituted EuTiO_(3) perovskites with cubic structure(space group pm3m)was successfully fabricated,and their magnetic properties as well as cryogenic magnetocaloric effects were investigated in *** expected,the introduction of Nb and Fe can significantly modulate the magnetic phase transition and magnetocaloric effect of the EuTiO_(3) *** increasing Fe concentration,two local minima corresponding to the AFM-FM magnetic phase transition near 5.0 K and FM-PM transition near 10 K with no hysteresis in the thermomagnetic curves are observed,which is attributed to an enhancement of FM *** the same time,the gradually widened-ΔSM-T curves and the two peaks with a broad shoulder lead to considerable refrigeration capacity(RC).With the field change ofΔH=2 T,the calculated values of-ΔS_(M)^(max) for the EuTi_(0.9375-x)Nb_(0.0625)Fe_(x)O_(3)(x=0.075,0.1,0.125,0.15)compounds are 24.2,17.6,14.5 and 14.0 j/(kg·K),*** corresponding RC values were calculated to be 144.6,138.3,151.2 and 159 j/kg,***,the values of-ΔS_(M)^(max) for EuTi_(0.8625)Nb_(0.0625)Fe_(0.075)O_(3) are 8.6 and 15.1 j/(kg·K)under low field changes of 0.5 and 1 T,*** giant low-field reversible magnetocaloric effect makes them attractive candidates for magnetic refrigeration in the liquid helium temperature region.

关键词： Magnetocaloric effect Refrigeration capacity Magnetic entropy change Rareearths

Guanine-derived F,N co-doped carbon-shell encapsulated iron carbide nanoparticles for enhanced CO_(2)electroreduction activity

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Nano Research 2024年第6期17卷 4744-4752页

作者： Shuo Chen Lishun Pei Ying Peng Xuefei Zhang Zailai xie Key Laboratory of Advanced Carbon-Based Functional Materials(Fujian Province University) Fuzhou UniversityFuzhou 350016China

The development of highly selective,cost-effective,and energy-efficient electrocatalysts is critical for carbon dioxide reduction reaction(CO_(2)RR)to produce high-value ***,we propose a facile strategy to obtain F,N co-doped carbon-coated iron carbide(Fe3C)nanoparticles by using biomolecule guanine and hexadecafluorophthalocyanine iron as raw ***,this method involves only one-step pyrolysis and does not require any guiding agent or sacrificial *** from the advantageous surface microenvironment adjustments achieved through graphitic N(GN)and F co-doping,Fe3C@NF-G-1000 demonstrates exceptional efficacy in the electroreduction of CO_(2)to carbon monoxide(CO)with an impressive Faradic efficiency(FEco)up to 98%at the potential of−0.55 V(*** hydrogen electrode(RHE)).Furthermore,it delivers a remarkable current density of up to−43 mA·cm^(−2)and exhibits virtually no current attenuation over a span of 20 h within the flow *** from density functional theory(DFT)calculations reveal that the composite structure of GN and F co-doped graphitic layer and Fe3C exhibits different electron density distributions from that of iron carbide *** is attributed to the synergistic effect of the composite structure leading to the enrichment of electrons in the graphite layer on the surface,which contributes to the stability of the key reaction intermediate*COOH,thus,resulting in an enhanced catalytic activity and ***,this work introduces a new and promising approach to the design of green and low-cost carbon-coated metal materials for CO_(2)reduction reactions.

关键词： guanine F,N co-doped carbon dioxide reduction reaction(CO_(2)RR) Fe-based catalyst

Insight into the Role and Evidence of Oxygen Vacancies in Porous Single-Crystalline Oxide to Enhance Catalytic Activity and Durability

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Research 2024年第2期2023卷 675-683页

作者： Lingting Ye jiaming Ma jie Zhang Wen Yin Yuanguang Xia Kui xie Key Laboratory of Optoelectronic Materials Chemistry and Physics Fujan Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian 350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China FuzhouFujian 350108China Advanced Energy Science and Technology Guangdong Laboratory 29 Sanxin North RoadHuizhouGuangdong 116023China Spallation Neutron Source Science Center DongguanGuangdong 523803China

Introducing and stabilizing oxygen vacancies in oxide catalysts is considered to be a promising strategy for improving catalytic activity and ***,we quantitatively create oxygen vacancies in the lattice of porous single-crystallineβ-Ga_(2)O_(3)monoliths by reduction treatments and stabilize them through the long-range ordering of crystal lattice to enhance catalytic activity and *** combination analysis of time-of-flight neutron powder diffraction and extended x-ray absorption fine structure discloses that the preferential generation of oxygen vacancy tends to occur at the site of tetrahedral coordination oxygen ions(O_(Ⅲ)sites),which contributes to the formation of unsaturated Ga-O coordination in the monoclinic *** oxygen vacancies are randomly distributed in lattice even though some of them are present in the form of domain defect in the PSC Ga_(2)O_(3)monoliths after the reduction *** number of oxygen vacancies in the reduced monoliths gives 2.32×10^(13),2.87×10^(13),and 3.45×10^(13)mg^(-1)for the Ga_(2)O_(2.952),Ga_(2)O_(2.895),and Ga_(2)O_(2.880),*** therefore demonstrate the exceptionally high C_(2)H_(4)selectivity of~100%at the C_(2)H_(6)conversion of~37%for nonoxidative dehydrogenation of C_(2)H_(6)to C_(2)H_(4).We further demonstrate the excellent durability even at 620℃for 240 h of continuous operation.

关键词： durability coordination Oxygen

Hovering rotor aerodynamics in extreme ground effect

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Chinese journal of Aeronautics 2024年第7期37卷 204-219页

作者： Zhenlong WU Tianyu ZHANG Huijun TAN Haoyu ZHOU Wei CHEN Maixiang xie College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China China Aviation Power Machinery Research Institute Zhuzhou 412002China

This paper presents an experimental and numerical study of the aerodynamics of a moderate-scale rotor hovering in the Extreme Ground Effect(EGE)where rotor height-offground is below half the rotor *** tip vortex field was visualized by using the PIV *** aerodynamic performance,tip vortex trajectory,wall jet characteristics,surface pressure and velocity fields were measured and *** explore more deeply the flow mechanisms of the extreme ground effect,Detached Eddy Simulation(DES)was conducted on completely structured *** results showed significant deviations of the rotor performance in EGE from that in Regular Ground Effect(RGE)with the rotor heights of more than half the rotor ***,the flow structures of the rotor in EGE are considerably complex,such as the wall jet and groundwash flow *** rotor wake flow and tip vortices impact the ground more frequently,resulting in distinctive characteristics of the surface pressure and velocity fields in EGE.

关键词： Rotor Ground effect Tip vortex Detached Eddy Simulation(DES) Groundwash

Construction of 2D/2D Ti_(3)C_(2)T_(x)MXene/CdS heterojunction with photothermal effect for efficient photocatalytic hydrogen production

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journal of Materials Science & Technology 2024年第4期171卷 1-9页

作者： T.Y.Huang Z.Yang S.Y.Yang Z.H.Dai Y.j.Liu j.H.Liao G.Y.Zhong Z.j.xie Y.P.Fang S.S.Zhang Key Laboratory for Biobased Materials and Energy of Ministry of Education Guangdong Laboratory for Lingnan Modern AgricultureCollege of Materials and EnergySouth China Agricultural UniversityGuangzhou 510643China School of Physics and Optoelectronics South China University of TechnologyGuangzhou 510640China School of Chemical Engineering and Energy Technology Guangdong Provincial Key Laboratory of Distributed Energy SystemsDongguan University of TechnologyDongguan 523808China

The insensitivity of semiconductors to visible and infrared light is a key constraint on the utilization of light energy in photocatalytic *** photocatalysts with full-spectrum absorption through surface engineering is an effective approach to fully harnessing light energy in semiconductor ***,a novel stable Ti_(3)C_(2)T_(x)MXene/CdS heterojunction catalyst is obtained by in-situ epitaxial growth of two-dimensional(2D)CdS nanosheets on 2D MXene interface via a solvothermal *** exceptional light absorption properties of MXene confer outstanding full-spectrum driven photocat-alytic hydrogen evolution capability upon the heterogeneous *** unique 2D/2D structure effectively mitigated the recombination of photogenerated carriers,enhancing the photocatalytic performance of the ***,the composite catalyst exhibits a significantly higher surface temperature of 80.4℃under visible light irradiation at an intensity of 0.1 W/cm^(2),which is 1.84 times higher than that of *** irradiation of visible and near infrared light,the composite catalyst with photothermal ef-fect demonstrates a remarkable hydrogen evolution rate of 65.4 mmol g^(-1)h^(-1),which is 7.2 times higher than that of CdS *** study introduces a novel approach for constructing full-spectrum absorption catalysts and expands the application of the photothermal effect in photocatalytic hydrogen evolution research.

关键词： Two-dimensional structure Heterostructure Photothermal effect Photocatalyst Hydrogen evolution

Experimental study on performance of spring damping support structure system for large deformation tunnel in soft rock

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Underground Space 2024年第2期15卷 221-243页

作者： jinfeng Xu Xiongyao xie Zhou Shi Wuqiang Cai Dinglun Xu Chen Xu Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering Ministry of EducationTongji UniversityShanghai 200092China Zhaotong City Zhaolu Expressway Investment and Development Co. ZhaotongYunnan Province 657000China Institute of Rock Mechanics Ningbo UniversityNingboZhejiang 315211China

According to the convergence confinement theory,it is an effective measure to control the large deformation of high ground stress in fractured soft rock tunnels by using yielding *** yielding support can be classified as either radial or circumferential yielding *** yielding support is achieved by transforming radial displacement into circumferential tangential closure without compromising the support capacity of the primary lining support *** on this,and inspired by the design principle of dampers,a yielding support structure system with spring damping elements as its core was developed,based on the connection characteristics of steel arches in highway tunnel,which can provide increasing support resistance in the yielding deformation *** the mechanical properties of spring damping elements were obtained through indoor axial pressure and flexural *** addition,according to these results with numerical calculations,the yielding support structure system with embedded spring damping elements can reduce the internal force of the support structure by approximately 10%and increase the area of the plastic zone of the surrounding rock by 11.23%,which can fully utilize the self-bearing capacity of surrounding rock and verify the effectiveness of circumferential yielding ***,the spring damping support structure system was designed with reference to the construction process of the tunnel excavated by drilling and blasting method,and the transformation of the spring damping element to spring damping support structure was *** on field test results,surrounding ground pressure for the yielding support optimization scheme was reduced by 40%and more evenly distributed,resulting in the successful application and a reduction in the construction cost of large deformation tunnels in soft rock.

关键词： Soft rock Highway tunnel Convergence confinement method Circumferential yielding support with spring damping element Numerical calculations Field test