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Effect of Incoming Vortex on Secondary Flows in Turbine Cascades with Planar and Non-Axisymmetric Endwall

Journal of Thermal Science 2024年第1期33卷 138-157页

作者： CAO Zhiyuan WANG Chuxuan SONG Zhigao gao xi ZHAO Wei LIU Bo School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical UniversityXi'an 710072China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100080China School of Aeronautics and Astronautics University of Chinese Academy of SciencesBeijing 100080China

Non-Axisymmetric Endwall Profiling(NAEP) is commonly utilized in turbines to eliminate secondary flows.Nevertheless,most of the NAEP methods consider a single-blade row environment without incorporating the effect of the stage environment.This paper aims to investigate the influence mechanism of the incoming vortex on the endwall secondary flow structures of NAEP in a highly loaded turbine cascade.To model the incoming vortex in a stage environment,this study considers a half-delta wing as the vortex generator at the upstream of the turbine cascade.The NAEP is then carried out for a highly loaded turbine cascade with an in-house numerical optimization design platform subject to no incoming vortex.Numerical simulation is also carried out under the influence of the incoming vortex for the turbine cascades with both planar and non-axisymmetric endwall.This paper furthers investigated the pitchwise effect of the incoming vortex on the near endwall secondary flow.The results indicate that the NAEP effectively improves the endwall secondary flow of the turbine cascade,where the total pressure loss coefficient and the secondary kinetic energy(SKE) are reduced by 7.3%,and 45.7%,respectively.It is further seen that with the incoming vortex,the NAEP achieves a considerable control effect on the endwall secondary flow of the turbine cascade.With incoming vortex,the NAEP can still achieve considerable control effect on the endwall secondary flow of the turbine cascade;the averaged reductions of loss coefficient and SKE are 7.8% and 14.2%,respectively.Under some pitchwise locations,incoming vortex can suppress the convection of cross-passage flow toward the suction corner greatly and reduce the loss coefficient of the baseline cascade.The incoming vortex at 4/7 pitch impinged right at the blade leading edge,leading to the generation of low-momentum fluid,which increased the size and the strength of the horseshoe vortex.Under all the pitchwise locations,NAEP can suppress the secondary vortices,e.g.,the passage vortex and the c

关键词： non-axisymmetric endwall secondary flow incoming vortex passage vortex stage environment

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Enhanced red luminescence of Ca_(3)Si_(2−x)M_(x)O_(7):Eu^(3+)(M=Al,P)phosphors via partial substitution of Si^(4+) for applications in white light-emitting diodes

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Rare Metals 2024年第2期43卷 736-748页

作者： Yu-Hao Ma xi gao Wen-Tao Zhang Zhen-Rui Yang Zhou Zhao Chen Qu College of Materials and Chemistry and Chemical Engineering Chengdu University of TechnologyChengdu610059China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu610059China International Advanced Energy Science Research and Education Center Graduate School of Energy ScienceKyoto UniversityYoshida-HonmachiKyoto606-8501Japan

A red-emitting phosphor Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) with partial Al^(3+)/P^(5+) substitution on Si^(4+) was synthesized via a simple solid-state method,and the effects of the introduction of the M^(3+/5+)(M=Al,P)ions on the crystal structure and photoluminescence performance of Ca_(2.91)Si_(2−x)M_(x)O_(7):0.09Eu^(3+) phosphors were investigated.The X-ray diffraction(XRD),energy-dispersive X-ray spectroscopy(EDS),and X-ray photoelectron spectroscopy(XPS)results revealed that the structure of Ca_(3)Si_(2)O_(7) remained the same after the introduction of Al^(3+) and P^(5+) ions.The characteristic emission of Eu^(3+)-doped Ca_(3)Si_(2−x)M_(x)O_(7) phosphors exhibited two main peaks at 617 nm(red)and 593 nm(orange)under excitation at 394 nm,which originated from the^(5)D_(0)→^(7)F_(2)and^(5)D_(0)→^(7)F_(1) electron transitions of Eu^(3+) ions.After the partial substitution of Al^(3+) and P^(5+),the red emission intensities of the Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) phosphors were significantly enhanced by 1.88-and 1.42-fold,respectively,which is attributed to the crystal-field effect around Eu^(3+).Meanwhile,the luminescence intensities of the Ca_(2.91)Si_(1.96)Al_(0.04)O_(7):0.09Eu^(3+) and Ca_(2.91)Si_(1.94)P_(0.06)O_(7):0.09Eu^(3+) phosphors at 210℃ were 79.36%and 77.53%of those at 30°C,respectively,indicating their excellent thermal stability.Moreover,the as-prepared Ca_(2.91)Si_(1.96)Al_(0.04)O_(7):0.09Eu^(3+)and Ca_(2.91)Si_(1.94)P_(0.06)O_(7):0.09Eu^(3+) red-emitting phosphors were combined with a near-ultraviolet chip of 395 nm to fabricate red-light-emitting diode(LED)and white(w)-LED devices with excellent chromaticity features.In summary,Al^(3+)/P^(5+)-substituted Ca_(2.91)Si_(2)O_(7):0.09Eu^(3+) can serve as red-emitting phosphors for applications in w-LEDs.

关键词： Ca_(3)Si_(2)O_(7) Red-emitting phosphor Structure substitution Luminescence enhancement Crystal-field effect White light-emitting diode

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Application of GNSS-PPP on Dynamic Deformation Monitoring of Offshore Platforms

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China Ocean Engineering 2024年第2期38卷 352-361页

作者： YU Li-na xiONG Kuan gao xi-feng LI Zhi FAN Li-long ZHANG Kai Institute of Ocean Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China China Railway Construction Bridge Engineering Bureau Group Co.LTD Tianjin 300300China School of Civil Engineering Tianjin UniversityTianjin 300072China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong KongChina State Key Laboratory of Precision Blasting Jianghan UniversityWuhan 430056China

The real-time dynamic deformation monitoring of offshore platforms under environmental excitation is crucial to their safe operation.Although Global Navigation Satellite System-Precise Point Positioning(GNSS-PPP)has been considered for this purpose,its monitoring accuracy is relatively low.Moreover,the influence of background noise on the dynamic monitoring accuracy of GNSS-PPP remains unclear.Hence,it is imperative to further validate the feasibility of GNSS-PPP for deformation monitoring of offshore platforms.To address these concerns,vibration table tests with different amplitudes and frequencies are conducted.The results demonstrate that GNSS-PPP can effectively monitor horizontal vibration displacement as low as±30 mm,which is consistent with GNSS-RTK.Furthermore,the spectral characteristic of background noise in GNSS-PPP is similar to that of GNSS-RTK(Real Time Kinematic).Building on this observation,an improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)has been proposed to de-noise the data and enhance the dynamic monitoring accuracy of GNSS-PPP.Field monitoring application research is also undertaken,successfully extracting and analyzing the dynamic deformation of an offshore platform structure under environmental excitation using GNSS-PPP monitoring in conjunction with improved CEEMDAN de-noising.By comparing the de-noised dynamic deformation trajectories of the offshore platform during different periods,it is observed that the platform exhibits reversible alternating vibration responses under environmental excitation,with more pronounced displacement deformation in the direction of load action.The research results confirm the feasibility and potential of GNSS-PPP for dynamic deformation monitoring of offshore platforms.

关键词： GNSS-PPP offshore platform dynamic deformation monitoring improved CEEMDAN de-noising

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Computational Study on the Boundary Layer Suction Effects in the Supersonic Compressor Flow with a Bowed Blade

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Journal of Thermal Science 2022年第2期31卷 511-528页

作者： CAO Zhiyuan SONG Cheng gao xi ZHANG xiang LIU Bo School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China

Flow control methodologies have been widely used to eliminating flow separation and increasing the blade load in axial compressor.Aiming at revealing the flow mechanism of coupled bowed blading and boundary layer suction in a supersonic compressor cascade,a cascade with a diffusion coefficient of 0.62 is numerically presented.First of all,according to the available experimental data,the numerical method was validated;then,different bowed blading effects on flow field in detail were investigated;at last,based on the flow physics of purely bowed blading,the positively bowed blade was coupled with boundary layer suction on blade suction surface,whereas the negatively bowed blade was coupled with endwall suction.For coupled control method,influence mechanism on flow field,especially on the shock structure was revealed,and different aspect ratios of coupled control method were investigated as well.Results showed that the coupled positively bowed blading and suction surface suction can eliminate the flow separation effectively.Compared with that of baseline supersonic cascade,the total pressure loss coefficient of the coupled scheme was reduced by 37.4%at most.At mid-span,the shock moved downstream and the single shock was separated to a dual-shock structure since the positively bowed blading reduced the static pressure of mid-span.The coupled negatively bowed blading and endwall suction also effectively enhanced the performance of cascade by removing the corner separation,with the loss coefficient reduced by as much as 41.9%.However,the suction coefficient of optimal coupled negatively bowed blading scheme reached 10.5%,which is too high for practical use.After coupled control,the 3 D shock structure became“C”shaped distribution along spanwise because of the difference in influence mechanism of negatively bowed blading on different spanwise location.Due to the opposite influence effect of positively and negatively bowed blading,the shock structure in the two different schemes of cascades were different and showed oppo

关键词： supersonic compressor cascade bowed blading boundary layer suction shock aspect ratio

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Comparison of Flow Mechanism of Blade Sweep between a Transonic Single Rotor and a Rotor in Stage Environment

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Journal of Thermal Science 2022年第5期31卷 1804-1819页

作者： CAO Zhiyuan gao xi LIANG Yuyuan HUANG Ping LEI Peng LIU Bo School of Power and Energy Northwestern Polytechnical UniversityXi’an710072China AECC Sichuan Gas Turbine Research Establishment Chengdu610599China

In order to reveal the different effect mechanisms of blade sweep on the aerodynamic performance when a transonic rotor operates alone or in fan stage environment,two series of forward and backward swept rotors were designed and utilized in the first stage of the dual-stage NASA CR-120859 fan.Results show that,the influence of sweep on the single rotor and the whole stage is different,indicating swept designs for rotor alone may not be suitable for the stage operations.The distinct effect of sweep is account for the difference of the flow field characteristic and stall mechanism of the single rotor and the rotor in the stage environment.The single rotor is tip limited and its stall mechanism is shock/tip leakage vortex(TLV)interaction,whereas the fan stage is hub limited and its stall mechanism is the severe corner separation at stage hub region.For the single rotor,forward sweep increases the stall margin(SM)for all sweep schemes,while backward sweep reduces it in general.For the fan stage,however,backward swept rotor significantly increases stall margin and the stall mechanism is changed to shock/TLV interaction.On the contrary,forward sweep reduces stall margin in general.The flow mechanism is that forward sweep reduces blade loading at tip region near leading edge(LE)and causes the shock to move downstream.Both the variations improve flow field at tip region,while backward sweep exerts an opposite effect.At hub region,backward sweep reduces radial flow tendency by varying radial pressure gradient,causing reduction of corner separation at rotor hub,while forward sweep enhances corner separation.Moreover,with increasing of swept height and swept angle,the chock mass flow,peak efficiency and total pressure ratio of forward sweep are reduced in general,while an opposite effect can be found for backward sweep.

关键词： sweep tip leakage flow shock corner separation transonic fan

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身体新知:在自然神学与自然科学之间

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近代史研究 2024年第1期 112-128,M0005,M0006页

作者：高晞复旦大学历史学系

18世纪以来,欧洲神学家大量运用自然科学的新成果阐释自然神学理论,如借用解剖学知识论证上帝缔造生命、规划自然秩序的合理性。他们构建的兼具神学与科学的身体观念在19世纪由西方传教士和医生传入中国。既有研究多强调西来新知的科学... 详细信息

18世纪以来,欧洲神学家大量运用自然科学的新成果阐释自然神学理论,如借用解剖学知识论证上帝缔造生命、规划自然秩序的合理性。他们构建的兼具神学与科学的身体观念在19世纪由西方传教士和医生传入中国。既有研究多强调西来新知的科学性面相,但忽略了其中所蕴含的传教诉求和殖民意识,故有必要从科学思想史的角度甄别自然神学语境下的身体观与自然科学框架下的解剖学之差异,进一步考察这套神学与科学混杂的“身体新知”在晚清中国的传播机制与接受情况。代表西方科学成果的生理解剖学知识,被传教士当作批判、否定中国医学和中国文化的利器,在中国知识界和医学界都产生深远影响。中国士人和医生对外来的“身体新知”作出不同反应。维新士人较少受到带有宗教色彩的“造化论”的影响,但部分接受西人对中国身体观的批评。中医群体修正了原有的观察方法和认知系统,重构传统的身体观念,发起以中医科学化为标志的自改革运动。

关键词：身体观自然神学解剖学中医科学化

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氨基酸高产菌株创制的关键技术

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生物工程学报 2024年第6期40卷 1711-1727页

作者：郭亮高熙张红霞山西师范大学生命科学学院山西太原030031 山西省微生物应用技术工程研究中心山西太原030031

氨基酸是构成蛋白质的基本单元,被广泛应用于食品、医药、饲料和化工等多个领域。利用微生物细胞工厂生产氨基酸,具备原料可再生、生产过程条件温和、产品纯度高、环境污染小等优点,能够助力实现碳中和。借助代谢工程和合成生物学技术,... 详细信息

氨基酸是构成蛋白质的基本单元,被广泛应用于食品、医药、饲料和化工等多个领域。利用微生物细胞工厂生产氨基酸,具备原料可再生、生产过程条件温和、产品纯度高、环境污染小等优点,能够助力实现碳中和。借助代谢工程和合成生物学技术,对大肠杆菌(Escherichia coli)和谷氨酸棒杆菌(Corynebacterium glutamicum)进行定向设计、改造与优化,创制了高产氨基酸的微生物细胞工厂,实现了支链氨基酸、天冬氨酸族氨基酸、谷氨酸族氨基酸和芳香族氨基酸的生物炼制。本文对高产氨基酸的大肠杆菌细胞工厂和谷氨酸棒杆菌细胞工厂创制过程进行分析,以期对高性能微生物细胞工厂的创制提供参考。

关键词：微生物细胞工厂支链氨基酸天冬氨酸族氨基酸谷氨酸族氨基酸芳香族氨基酸

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Nd^(3+):GdScO_(3)晶体场能级及拟合分析

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物理学报 2024年第4期73卷 1-8页

作者：樊颖张庆礼高进云高宇茜黄磊刘耀安徽大学物质科学与信息技术研究院合肥230601 中国科学院合肥物质科学研究院安徽光学精密机械研究所安徽省光子器件与材料重点实验室合肥230031 先进激光技术安徽省实验室合肥230037 中国科学技术大学合肥230022

采用提拉法生长出了钕掺杂钪酸钆晶体(Nd^(3+):GdScO_(3)),通过低温吸收光谱和室温发射光谱,对其中Nd^(3+)的实验能级进行分析指认,确定了Nd^(3+):GdScO_(3)的66个实验Stark能级,拟合了其自由离子参数和晶体场参数,拟合均方根误差为13.1... 详细信息

采用提拉法生长出了钕掺杂钪酸钆晶体(Nd^(3+):GdScO_(3)),通过低温吸收光谱和室温发射光谱,对其中Nd^(3+)的实验能级进行分析指认,确定了Nd^(3+):GdScO_(3)的66个实验Stark能级,拟合了其自由离子参数和晶体场参数,拟合均方根误差为13.17 cm^(–1).与Nd^(3+):YAP和Nd^(3+):YAG相比,Nd^(3+):GdScO_(3)的晶场强度较弱.弱的晶体场强度有可能是Nd^(3+):GdScO_(3)晶体具有优良激光特性的原因之一.本文数据集可在https://***/10.57760/sciencedb.15702中访问获取.

关键词： Nd^(3+):GdScO_(3)晶体晶体场参数能级拟合

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存贷比对银行风险的影响及其机制分析——基于中国银行业的实证研究

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经济体制改革 2024年第3期 132-139页

作者：高嘉璘王雪标高西大连财经学院经济学院辽宁大连116025 东北财经大学经济学院辽宁大连116025

完善存贷比监管政策对于防范银行风险、维护金融稳定具有重要意义。基于我国2010~2020年67家商业银行的面板数据,探究存贷比对银行风险的影响及作用机制。实证结果表明:存贷比的提高能有效地降低银行风险;存贷比降低银行风险存在资本充... 详细信息

完善存贷比监管政策对于防范银行风险、维护金融稳定具有重要意义。基于我国2010~2020年67家商业银行的面板数据,探究存贷比对银行风险的影响及作用机制。实证结果表明:存贷比的提高能有效地降低银行风险;存贷比降低银行风险存在资本充足率、同业资产以及影子银行业务的中介效应;当资本充足率为门槛变量时,存贷比降低银行风险呈“边际效应”递增的非线性影响;当同业资产、影子银行业务为门槛变量时,存贷比降低银行风险呈“边际效应”递减的非线性影响。鉴于此,监管机构应加强对存贷比作为流动性检测指标的监管,鼓励商业银行构建资本补充的长效机制,加强对同业资产以及影子银行业务的风险管控,从而提升金融监管效果,守住不发生金融风险的底线。

关键词：存贷比银行风险资本充足率同业资产影子银行

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高航速流动不分离外形带攻角流动特性分析

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船舶力学 2024年第4期28卷 541-550页

作者：可伟王哲李晓植高全喜河北汉光重工有限责任公司河北省双介质动力技术重点实验室河北邯郸056017

边界层发生分离的两个必要条件是流体粘性和正压梯度,设计外形使其表面具有尽量大的负压梯度区域,延缓边界层转捩和流动分离,从而达到减阻目的。本文采用基于细长体理论的流动不分离外形设计方法,设计临界速度为100 m/s的航行体外形,运... 详细信息

边界层发生分离的两个必要条件是流体粘性和正压梯度,设计外形使其表面具有尽量大的负压梯度区域,延缓边界层转捩和流动分离,从而达到减阻目的。本文采用基于细长体理论的流动不分离外形设计方法,设计临界速度为100 m/s的航行体外形,运用数值仿真分析其在不同速度和攻角情况下的流动特性。研究发现,0°攻角下仿真得到的压强分布与理论计算结果一致,摩擦阻力与估算结果一致,证明可以通过外形设计使航行体边界层在高雷诺数条件下保持层流流动不分离状态,以达到大幅减阻的目的;小攻角不会破坏航行体表面流体附着状态,但攻角会使流动出现横向漩涡,边界层发生转捩,使阻力明显增加,但减阻效果仍然存在。

关键词：高速航行体流动不分离临界雷诺数层流攻角转捩

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