检索结果-南通市图书馆

Development of the detonation-driven expansion tube for orbital speed experiments

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2015年第4期58卷 695-700页

作者： JIANG Zong Lin WU Bo GAO Yun Liang ZHAO Wei HU Zong Min state key laboratory of high-temperature gas dynamics Institute of Mechanics Chinese Academy of Sciences

The hypersonic flow at orbital speeds is a fundamental issue for the ground tests of aerospace *** detonation-driven high-enthalpy expansion tube(JF16 expansion tube)was developed to investigate re-entry physics.A forward detonation cavity(FDC)driver was applied in the JF16 expansion tube to create stable driving *** sound speed ratio of the detonated to test gas was examined to minimize the magnitude of test flow *** acceleration section length,incident shock decay and diaphragms thickness were investigated in detail to obtain optimal operation *** visualization was also carried out with schlieren system to demonstrate the test flow stability and the effective test *** data showed that the test flow with a velocity of 8.3 km/s and a total enthalpy up to 40 MJ/kg can be generated successfully and the test duration lasts for more than 50μs.

关键词： detonation driver shock-expansion tube high-enthalpy flow test flow

Numerical investigation on the thermal protection mechanism for blunt body with forward-facing cavity

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2016年第7期59卷 1120-1129页

作者： LI XinDong HU ZongMin JIANG ZongLin state key laboratory of high temperature gas dynamics Institute of Mechanics Chinese Academy of Sciences

Numerical experiments are carried out using the standard hypersonic ballistic-type model(HB-2) to investigate the effect of forward-facing cavity on the aerodynamic heating. A general concept is proposed which utilizes the flow disturbances generated passively in the nosed subsonic region to weaken the detached shock wave. Several aspects are mainly studied, including shock shape and standoff distance, surface heat flux and pressure, flowfield feature and cooling mechanism. The numerical results indicate that shock strength and standoff distance increase with an increase in the L/D ratio of the cavity. Interestingly, a bulge structure of the detached shock associated with a deep cavity is observed for the first time. Local surface heat flux and pressure around the concave nose are much lower respectively than those at the stagnation point of the baseline model. In addition, both surface heat and pressure reductions are proportional to the L/D ratio. A negative heating phenomenon may occur in the vicinity of a sharp lip or on the base wall of a deep cavity. If the L/D ratio exceeds 0.7, the detached shock appears as a self-sustained oscillation which can be referred to as the cooling mechanism.

关键词： hypersonic flow aerodynamic heating thermal protection system forward-facing cavity

Aerothermal characteristics of bleed slot in hypersonic flows

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2015年第10期58卷 46-59页

作者： YUE LianJie LU HongBo XU Xiao CHANG XinYu state key laboratory of high temperature gas dynamics Institute of Mechanics Chinese Academy of Sciences

Two types of flow configurations with bleed their aerodynamic thermal loads and related in two-dimensional hypersonic flows flow structures at choked conditions. are numerically examined to investigate One is a turbulent boundary layer flow without shock impingement where the effects of the slot angle are discussed, and the other is shock wave boundary layer in- teractions where the effects of slot angle and slot location relative to shock impingement point are surveyed. A key separation is induced by bleed barrier shock on the upstream slot wall, resulting in a localized maximum heat flux at the reattachment point. For slanted slots, the dominating flow patterns are not much affected by the change in slot angle, but vary dramatically with slot location relative to the shock impingement point. Different flow structures are found in the case of normal slot, such as a flow pattern similar to typical Laval nozzle flow, the largest separation bubble which is almost independent of the shock position. Its larger detached distance results in 20% lower stagnation heat flux on the downstream slot corner, but with much wider area suffering from severe thermal loads. In spite of the complexity of the flow patterns, it is clearly revealed that the heat flux generally rises with the slot location moving downstream, and an increase in slot angle from 20° to 40° reduces 50% the heat flux peak at the reattachment point in the slot passage. The results further indicate that the bleed does not raise the heat flux around the slot for all cases except for the area around the downstream slot corner. Among all bleed configurations, the slot angle of 40° located slightly upstream of the incident shock is regarded as the best.

关键词： boundary layer control boundary layer heat flow shock wave interactions separated flows

Comparative study on aerodynamic heating under perfect and nonequilibrium hypersonic flows

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2016年第2期59卷 78-84页

作者： Qiu Wang Jin Ping Li Wei Zhao Zong Lin Jiang state key laboratory of high temperature gas dynamics Institute of Mechanics Chinese Academy of Sciences

In this study, comparative heat flux measurements for a sharp cone model were conducted by utilizing a high enthalpy shock tunnel JF-10 and a large-scale shock tunnel JF-12, responsible for providing nonequilibrium and perfect gas flows, respectively. Experiments were performed at the key laboratory of high temperature gas dynamics(LHD), Institute of Mechanics, Chinese Academy of Sciences. Corresponding numerical simulations were also conducted in effort to better understand the phenomena accompanying in these experiments. By assessing the consistency and accuracy of all the data gathered during this study, a detailed comparison of sharp cone heat transfer under a totally different kind of freestream conditions was build and analyzed. One specific parameter, defined as the product of the Stanton number and the square root of the Reynold number, was found to be more characteristic for the aerodynamic heating phenomena encountered in hypersonic flight. Adequate use of said parameter practically eliminates the variability caused by the deferent flow conditions, regardless of whether the flow is in dissociation or the boundary condition is catalytic. Essentially, the parameter identified in this study reduces the amount of ground experimental data necessary and eases data extrapolation to flight.

关键词： aerodynamic heating hypersonic shock tunnel Stanton number sharp cone

Trinuclear gold-catalyzed site-selective alkylation of peptides

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第01期 249-256页

作者： Qing-Yun Fang Chengyihan Gu Yinghan Chen Wencheng Yan Yong Liang Weipeng Li Chengjian Zhu Jie Han Jin Xie state key laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic Materials Chemistry and Biomedicine Innovation Center (Chem BIC) School of Chemistry and Chemical Engineering Nanjing University Green Catalysis Center College of Chemistry Zhengzhou University state key laboratory of Natural Medicines China Pharmaceutical University

Selective modification of peptides has always been a challenging issue. The selective alkylation of peptides can alter the biological activity and physical properties of molecules, and it has gained significant research interest. We herein disclose an intriguing gold-catalyzed alkylation of peptides using bench-stable unactivated alkyl bromides under photoredox catalysis. A wide range of structurally diverse primary, secondary and tertiary alkyl bromides serve as effective coupling partners to precisely connect with the α-C(sp3)–H in glycine residue of peptides. This protocol demonstrates an exceptionally broad scope for alkyl halides and excellent tolerance for a wide range of useful functional groups. A series of relay transformations to construct cyclic peptides, to proceed click reaction and to realize peptide fluorescence labeling further enhance its synthetic practicality. In addition, mechanistic studies and density functional theory(DFT) calculations reveal an inner-sphere and subsequent outersphere single electron transfer(SET) mechanism.

关键词：

Investigation of bubbles escape behavior from low basicity mold flux for high-Mn high-Al steels using 3D X-ray microscope

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 102-110页

作者： Qiang Liu Xiang Li Shen Du Ming Gao Yanbin Yin Jiongming Zhang state key laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

During the continuous casting process of high-Mn high-Al steels,various types of gases such as Ar need to escape through the top of the *** which,the behavior of bubbles traversing the liquid slag serves as a restrictive link,closely associated with viscosity and the thickness of liquid *** contrast to two-dimensional surface observation,three-dimensional(3D)analysis method can offer a more intuitive,accurate,and comprehensive ***,this study employs a 3D X-ray microscope(3D-XRM)to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag,different temperatures,and different holding *** results indicate that as basicity of slag increases from 0.52 to 1.03,temperature increases from 1423 to 1573 K,the viscosity of slag decreases,the floating rate of bubbles *** addition,when holding time increases from 10 to 30 s,the bubbles floating distance increases,and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually *** one word,increasing the basicity,temperature,and holding time leading to an increase in the removal rate of bubbles especially for the *** findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.

关键词： mold flux low basicity bubbles three-dimensional X-ray microscope viscosity

Engine performance analysis and optimization of a dual-mode scramjet with varied inlet conditions

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2016年第1期32卷 75-82页

作者： Lu Tian Li-Hong Chen Qiang Chen Feng-Quan Zhong Xin-Yu Chang state key laboratory of high-temperature gas dynamicsInstitute of Mechanics Chinese Academy of SciencesBeijing 100190China

A dual-mode scramjet can operate in a wide range of flight conditions. higher thrust can be generated by adopting suitable combustion modes. Based on the net thrust, an analysis and preliminary optimal design of a kerosene-fueled parameterized dual-mode scramjet at a cru- cial flight Mach number of 6 were investigated by using a modified quasi-one-dimensional method and simulated annealing strategy. Engine structure and heat release distrib- utions, affecting the engine thrust, were chosen as analytical parameters for varied inlet conditions （isolator entrance Mach number： 1.5-3.5）. Results show that different opti- mal heat release distributions and structural conditions can be obtained at five different inlet conditions. The highest net thrust of the parameterized dual-mode engine can be achieved by a subsonic combustion mode at an isolator entrance Mach number of 2.5. Additionally, the effects of heat release and scramjet structure on net thrust have been discussed. The present results and the developed analytical method can provide guidance for the design and optimization of high-performance dual-mode scramjets.

关键词： Dual-mode scramjet Engine performance Thrust Optimization Heat release distribution Simulatedannealing algorithm

Train model acceleration and deceleration

在线全文

学校读者我要写书评

暂无评论

Science China Technological Sciences 2013年第3期56卷 642-647页

作者： YANG QianSuo SONG JunHao LI Duo ZHANG Jie YANG GuoWei state key laboratory of high temperature gas dynamics Institute of MechanicsChinese Academy of Sciences

In order to accelerate a heavy train model with great dimensions to a speed higher than 300 km h?1 in a moving train model testing system,compressed air is utilized to drive the train model *** gas from an air gun pushes the piston in an accelerating tube *** piston is connected to the trailer through a rope,and the trailer pulls the train model to the desired *** the testing section,the train model enters the deceleration *** speed of the train model gradually decreases because of the braking force of the magnetic braking device on the bottom of the train model and the steel plates fixed on the floor of this *** dissipation of kinetic energy of the trailer is also based on a similar *** feasibility of these methods has been examined in a 180 m-long moving train model testing *** speed of the trailer alone reaches up to 490 km ***,a 34.8 kg model accelerates up to 350 km h?1;the smooth and safe stopping of the model is also possible.

关键词： moving train model acceleration deceleration magnetic braking air gun compressed air

Flow characteristics of hypersonic inlets with different cowl-lip blunting methods

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2014年第4期57卷 741-752页

作者： LU HongBo YUE LianJie CHANG XinYu state key laboratory of high temperature gas dynamics Institute of Mechanics Chinese Academy of Sciences

Under hypersonic flight conditions,the sharp cowl-lip leading edges have to be blunted because of the severe aerodynamic *** paper proposes four cowl-lip blunting methods and studies the corresponding flow characteristics and performances of the generic hypersonic inlets by numerical simulation under the design conditions of a flight Mach number of 6 and an altitude of 26 *** results show that the local shock interference patterns in the vicinity of the blunted cowl-lips have a substantial influence on the flow characteristics of the hypersonic inlets even though the blunting radius is very small,which contribute to a pronounced degradation of the inlet *** Equal Length blunting Manner(ELM)is the most optimal in that a nearly even reflection of the ramp shock produces an approximately straight and weak cowl reflection *** minimal total pressure loss,the lowest cowl drag,maximum mass-capture and the minimal aeroheating are achieved for the hypersonic *** the other blunting manners,the ramp shock cannot reflect evenly and produces more curved cowl reflection *** Type V shock interference pattern occurs for the Cross Section Cutting blunting Manner(CSCM)and the strongest cowl reflection shock gives rise to the largest flow loss and *** cowl-lip blunted by the other two blunting manners is subjected to the shock interference pattern that transits with an increase in the blunting ***,the peak heat flux does not fall monotonously with the blunting radius ***,the cowl-lip surface suffers from severe aerothermal load when the shear layer or the supersonic jet impinges on the wall.

关键词： hypersonic inlet cowl-lip bluntness flow characteristics shock pattern shock interference