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RANS simulations on combustion and emission characteristics of a premixed NH_(3)/H_(2) swirling flame with reduced chemical kinetic model

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Chinese Journal of Aeronautics 2021年第12期34卷 17-27页

作者： Yuze sun Tao CAI Mohammad SHAHSAVARI Dakun sun xiaofeng sun Dan ZHAO Bing WANG Department of Mechanical Engineering University of CanterburyChristchurch 8041New Zealand School of Aerospace Engineering Tsinghua UniversityBeijing 100084China Collaborative Innovation Center for Advanced Aero-Engine Beihang UniversityBeijing 100083China

Ammonia(NH_(3))is considered as a potential alternative carbon free fuel to reduce greenhouse gas emission to meet the increasingly stringent emission ***-burning NH_(3) and H_(2) is an effective way to overcome ammonia’s relative low burning *** this work,3D Reynolds Averaged Navier-Stokes(RANS)numerical simulations are conducted on a premixed NH_(3)/H_(2) swirling flame with reduced chemical kinetic *** effects of(A)overall equivalence ratio Φ and(B)hydrogen blended molar fraction XH2 on combustion and emission characteristics are *** present results show that when 100%NH_(3)-0%H_(2)-air are burnt,the NO emission and unburned NH3 of at the swirling combustor outlet has the opposite varying *** the increase of Φ,NO emission is found to be decreased,while the unburnt ammonia emission is ***_(2)→HNO,NH→HNO and HNO→NO sub-paths are found to play a critical role in NO *** reaction rate of all these three sub-paths is shown to be decreased with increased Φ.Hydrogen addition is shown to significantly increase the laminar burning velocity of the mixed ***,adding H_(2) does not affect the critical equivalence ratio corresponding to the maximum burning *** emission trend of NO and unburnt NH_(3) with increased Φ is unchanged by blending H_(2).NO emission with increased X_(H2) is increased slightly less at a larger Φ than that at a smaller Φ.In addition,reaction rates of NH_(2)→HNO and HNO→NO sub-paths are decreased with increased X_(H2),when Φ is *** all tested cases,blending H_(2) with NH_(3) reduces the unburned NH_(3) emission,especially for rich combustion *** summary,the present work provides research finding on supporting applying ammonia with hydrogen blended in low-emission gas turbine engines.

关键词： Ammonia Emission Hydrogen Premixed combustion Reduced mechanism Swirling flame

Effect of wire mesh casing treatment on axial compressor performance and stability

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Chinese Journal of Aeronautics 2024年第3期37卷 60-76页

作者： Ming ZHANG Jiaming ZHANG Jiahao HU Xu DONG Dakun sun xiaofeng sun School of Energy and Power Engineering Beihang UniversityBeijing 100191China Beihang Hangzhou Innovation Institute Yuhang Hangzhou 310023China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China

In this paper,a kind of Wire Mesh Casing Treatment(WMCT)is proposed to improve the stable operating range of the *** contrast to the traditional circumferential groove,as for WMCT,a layer of wire mesh is laid on the surface of the circumferential *** studies were conducted on the low-speed axial flow compressor,including the groove width,axial location,and mesh *** optimum axial location for WMCT is related to its groove width.A higher wire mesh count results in a smaller compressor stall margin *** simulations were carried out to study the effect of WMCT on the flow structure of the *** wire mesh in the WMCT has a certain flow resistance,which restricts the flow into and out of the *** to the WMCT,the flow parameter in the tip region of the rotor is less sensitive to changes in the operating conditions of the *** WMCT causes the rotor tip blade loading to shift backward,inhibiting the formation of spill forward of the leakage flow,and thus improving the stability of the *** flow resistance on the groove surface is a new degree-of-freedom for the casing treatment designer.

关键词： Axial compressor Wire mesh casing treatment Tip clearance flow Stall margin Blade loading

Research on Properties of Carbon Fiber/Epoxy Resin Composite Material by Microwave Curing

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稀有金属材料与工程 2012年第S1期41卷 422-424页

作者： sun xiaofeng Ma Shining Liu Hongwei Acad Armored Forces Engn Natl Key Lab Remfg Beijing 100072 Peoples R China

Microwave irradiation was used to reduce the curing time of carbon fiber/epoxy resin composite *** properties of carbon fiber/epoxy resin composite material under microwave curing were investigated by thermogravimetry(TG),dynamic mechanical analysis(DMA),impact strength test and scanning electron microscope(SEM).The results show that composite materials patch have high thermal stability after microwave *** initial degradation temperature is 330.9℃,the maximum thermal decomposition rate is at 368.1℃.When the layer of composite materials patchis 4 layers,the dynamic mechanical properties are the best after microwave *** initial storage modulus is 43.2 GPa,increased 28.3 GPa and 27.1 GPa than 3 layers and 5 layers,the glass transition temperature(Tg)is 67.48℃,increased about 12 ℃than 3 layers and 5 *** curing can significantly improve the infiltration capacity of epoxy resin,enhance interfacial bonding,and increase the impact strength of composite *** microwave curing,the impact strength of 3,4,5-layers composite material patches increases 35.9%,6.4% and 15.1%,respectively than heating *** SEM analysis of impact fracture surface shows that microwave curing can improve the interface of carbon fiber and epoxy resin.

关键词： microwave curing carbon fiber composite material property

Recent advances in the stereolithographic three-dimensional printing of ceramic cores: Challenges and prospects

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Journal of Materials Science & Technology 2022年第22期117卷 79-98页

作者： Jinguo Li Xiaolong An Jingjing Liang Yizhou Zhou xiaofeng sun Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Space Manufacturing Technology(Chinese Academy of Sciences Key Laboratory) Beijing 100094China

The increasing demand for geometrically complex structures—specifically, higher-inlet-temperature turbine blades for the fifth-generation or other high-generation machines of advanced fighter aircrafts—hasmade the development of more complex double-walled three-layer hollow-cavity structures a ***, this requires the preparation of complex ceramic cores and advanced, integrated *** three-dimensional printing (SLA-3DP) technology, with digital control upon materialmorphology, composition, and structure, is a high integration and versatile technique that is superior tothe traditional manufacturing techniques for ceramic cores, including gel casting, injection molding, andhot pressing. The latent capacity of this technique is contingent on the progress of processing routesthat significantly reduce the distortion and defect formation in response to the elimination of the reactedorganic monomer phase during photo-curing. Despite the tremendous progress in the field, multiple challenges remain, such as the preparation of high-solid-content and low-viscosity suspensions, SLA-3DP oflarge double-walled ceramic cores with complex structures, and process optimization and sinter strengthening for the fabrication of ceramic cores. These challenges have prevented the broader applications andreduced the impact of the SLA-3DP technology. This review discusses cutting-edge research on the crucialfactors governing this production method. Specifically, we outline the existing challenges within the fieldand provide our perspective on the upcoming research work and progress.

关键词： Stereolithographic three-dimensional printing Ceramic cores,Cutting-edge research

Effects of Al on microstructural stability and related stress-rupture properties of a third-generation single crystal superalloy

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Journal of Materials Science & Technology 2019年第11期35卷 2537-2542页

作者： Jingxia sun Jinlai Liu Lirong Liu Yizhou Zhou Jinguo Lia xiaofeng sun Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China Space Manufacturing Technology Key Lab Chinese Academy of SciencesBeijing 100094China

To examine the influences of minor modification of Al content on the microstructural stabilities and stress rupture properties,two alloys with minor difference in Al content were exposed isothermally at 1100℃for 100 h,500 h,and 1000 h,*** microstructures were characterized before and after thermal *** was found that when Al content was decreased by 0.4 wt%,the volume fractionγ'decreased by 4%,the size ofγ'increased by 40 nm,the matrix channel width increased by 5 nm,and the misfit degree ofγ/γ'phases increased by 0.006%after heat treatment(HT).During thermal exposure,the alloy with low Al content had a better resistance to coarsening ofγ'phase and precipitation ofμ***γ'particles of the alloy with high AI content tended to connect each other and coarsened alongdirections;however,theγ'particles of the alloy with low Al content remained cubic after 500 h.A serious coarsening behavior took place in the two alloys after aging for 1000 *** structural stabilities were significantly ***,the change of 0.4 wt%Al content was found to have little effect on the high temperature stress-rupture properties.

关键词： Ni base single crystal superalloys Thermal exposure Microstructural stability Stress-rupture property Al

Application of Stall Warning Approach with Stall Precursor-Suppressed Casing Treatment on a Two-Stage Compressor

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Journal of Thermal Science 2019年第5期28卷 862-874页

作者： XU Ruize sun Dakun DONG Xu LI Fanyu sun xiaofeng LI Jia Fluid and Acoustics Engineering Laboratory School of Energy and Power Engineering Beihang University

A stall warning approach based on aero-acoustic theory is studied in this paper. For this stall warning approach, a parameter Rc is defined to measure the periodicity of the blade-passing signal. Signal simulation is used to investigate the mechanism of the stall warning approach. The results suggest that the value of Rc is influenced by the power of the perturbations. The experiments on a two-stage compressor indicate this stall warning approach can generate a warning signal several seconds before the stall. It is demonstrated in this paper that the stall warning approach can detect the distribution and evolution of stall precursors. According to the distribution of the stall precursors, the partial stall precursor-suppressed casing treatment is applied and realized a stabilization of compressor.

关键词： axial compressor stall warning casing treatment

Effect of C and Hf Contents on the Interface Reactions and Wettability between a Ni_3Al-Based Superalloy and Ceramic Mould Material

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Journal of Materials Science & Technology 2016年第2期32卷 177-181页

作者： Xiaoyan Chen Yizhou Zhou Tao Jin xiaofeng sun Institute of Metal Research Chinese Academy of Sciences

The influence of active elements C and Hf on the interface reactions and wettability between a Ni3Albased superalloy and the ceramic mould material was studied by using a sessile drop experiment, The microstructure of the alloy interface was investigated by scanning electron microscopy analysis and the phase identification was performed by X-ray diffraction analysis, The results show that interface reactions occur as C and Hf contents reach a critical value, The critical values for C and Hf to cause interface reactions are 0,12 wt% and 1,17 wt%, respectively, The reaction products contain HfO2 and 9Al2OH,Cr2O3, Adsorptions of Hf and interface reactions improve the wettability obviously,

关键词： Superalloys Ceramic Interface reaction Wettability C Hf

Evolution of Grain Selection in Spiral Selector during Directional Solidification of Nickel-base Superalloys

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Journal of Materials Science & Technology 2011年第2期27卷 118-126页

作者： Xiangbin Meng Jinguo Li Tao Jin xiaofeng sun Changbo sun Zhuangqi Hu Institute of Metal Research Chinese Academy of SciencesShenyang 00China Graduate School of Chinese Academy of Sciences Beijing 000China Shenyang Liming Aero-engine(Group) Corporation Ltd. Aviation Industry Corporation of China(AVIC)Shenyang 110043China

The process of grain selection in the spiral selector was investigated by both a ProCAST simulation based on a cellular automaton finite element（CAFE） model and experimental *** results show that the height of starter block,the spiral diameter and initial angle play an important role in grain *** dimension of selector should be maintained in a stable range to optimize the grain orientation and select a single crystal efficiently.A selector which can efficiently select a single crystal had been successfully *** orientation fluctuation in the spiral part was also studied by means of the variation of thermal condition.

关键词： Ni-base single crystal superalloys Grain selection Directional solidification

Microstructure and tensile properties of DD32 single crystal Ni-base superalloy repaired by laser metal forming

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Journal of Materials Science & Technology 2020年第10期42卷 23-34页

作者： Shiwei Ci Jingjing Liang Jinguo Li Yizhou Zhou xiaofeng sun Institute of Metal Research Chinese Academy of SciencesShenyang J10016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China Space Manufacturing Technology(CAS Key Lab) Beijing 100094China

In this work,the microstructure and tensile properties of DD32 single-crystal(SC)superalloy repaired by laser metal forming(LMF)using pulsed laser have been studied in *** microstructures of the deposited samples and the tensile-ruptured samples were characterized by optical microscopy(OM),transmission electron microscope(TEM)and scanning electron microscope(SEM).Due to high cooling rate,the primary dendrite spacing in the deposited area(17.2μm)was apparently smaller than that in the substrate area(307μm),and the carbides in the deposited samples were also smaller compared with that in the substrate *** formation of(γ+γ’)eutectic in the initial layer of repaired SC was inhibited because of the high cooling *** the deposition proceeded,the cooling rate decreased,and the(γ+γ’)eutectic increased ***(γ+γ’)eutectic at heat-affected zone(HAZ)in the molten pool dissolved partly because of the high temperature at HAZ,but there were still residual *** test results showed that tensile behavior of repaired SC at different temperatures was closely related to the MC carbides,solidification porosity,γ’phase,and(γ+γ’)*** moderate temperature,the samples tested fractured preferentially at the substrate area due to the fragmentation of the coarse MC carbide in the substrate *** elevated temperature,the(γ+γ’)eutectic and solidification porosity in the deposited area became the source of cracks,which deteriorated the high-temperature properties and made the samples rupture at the deposited area preferentially.

关键词： DD32 Pulsed-laser Repairing Single-crystal superalloy Microstructures Tensile property