检索结果-南通市图书馆

Acta Mechanica Sinica 2011年第6期27卷 891-897页

作者： Yu Pan Jian-guo Tan Jian-Han Liang Wei-Dong Liu zhen-guo wang Department of Aerospace and Material National University of Defense and Technology 410073 Changsha China

A scramjet combustor with double cavitybased flameholders was experimentally studied in a directconnected test bed with the inflow conditions of M = 2.64,Pt = 1.84 MPa,Tt = 1 300 *** ignition and selfsustained combustion with room temperature kerosene was achieved using pilot hydrogen,and kerosene was vertically injected into the combustor through 4×φ 0.5 mm holes mounted on the *** different equivalence ratios and different injection schemes with both tandem cavities and parallel cavities,flow fields were obtained and compared using a high speed camera and a Schlieren *** revealed that the combustor inside the flow field was greatly influenced by the cavity installation scheme,cavities in tandem easily to form a single side flame distribution,and cavities in parallel are more likely to form a joint flame,forming a choked combustion *** supersonic combustion flame was a kind of diffusion flame and there were two kinds of combustion *** the unchoked combustion mode,both subsonic and supersonic combustion regions *** in the choked mode,the combustion region was fully subsonic with strong shock propagating *** also showed that there was a balance point between the boundary separation and shock enhanced combustion,depending on the intensity of heat release.

关键词： Scramjet. Supersonic combustion. Flame structure Cavity flameholder

Erosion behavior of a ship propeller material of QAl9-4 alloy

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2023年第7期42卷 2390-2395页

作者： Wei-Jiu Huang Yong-Tao Zhou zhen-guo wang Zhi-Kang Liao School of Materials Science and Engineering Chongqing University of TechnologyChongqing400054China School of Materials Science and Engineering Beihang UniversityBeijing100191China

The erosion behavior of a QA19-4 alloy as a ship propeller material was *** effects of the solution,the impact angles and the sand content were *** test results demonstrate that the mass loss of the alloy in 3.5 wt%NaCl solution is 1.35 times that in tap water,due to the corrosive effect of Cl^(-).The mass loss of the alloy increases as the impact angle increases up to~30°and consequently decreases as the impact angle ***,this feature is typical for the ductile metal *** the impact angle of 0°,this feature is associated with the predominant erosion mechanisms,such as shallow plowing and surface fatigue;at 30°,this feature is micro-cutting,deep plowing and surface fatigue;and at 45°,it becomes indentation accompanied by extruded *** mass loss and surface roughness of the alloy increase as the sand content increases under the testing conditions.

关键词： Erosion QAl9-4 alloy Impact angle Sand content Erode surface

Crack Properties of Lean Duplex Stainless Steel 2101 in Hot Forming Processes

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2011年第4期18卷 58-62页

作者： FANG Yi-liu LIU zhen-yu wang guo-dong State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

The crack behavior of LDX 2101 by hot compression tests in the temperature range of 950 to 1150 ℃ and strain rate range of 0.01 to 30 s-1 was *** hot workability map of LDX 2101 was constructed and the alloy exhibited a better crack resistance at higher temperature and lower strain *** initiated and coalesced into crack at subsurface on the equatorial plane of bulge surface under secondary tensile *** cracks were orientated at an angle of approximately 45° with respect to the compression axis due to the secondary tensile *** easily initiated on the interface of ferrite and austenite and propagated within *** predicted results using specific plastic work approach were matched well with the free surface cracks.

关键词： lean duplex stainless steel hot workability crack specific plastic work approach

Development of Ti-Microalloyed 600 MPa Hot Rolled High Strength Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2010年第12期17卷 54-58,64页

作者： YI Hai-long LIU zhen-yu wang guo-dong WU Di State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 Liaoning China

A high strength steel with yield strength on the order of 600 MPa was developed successfully with only addition of titanium alloying element based on a low-carbon steel. The results showed that the hot deformation accelerated ferrite and pearlite transformation and retarded bainite transformation under continuous cooling condition. The microstructure of this steel was mainly composed of fine grained ferrite and carbides distributing along the ferrite grain boundaries. The yield and tensile strengths of steels were about 620--650 MPa and 720--740 MPa, respectively, and the values of strain hardening exponent and plastic strain ratio were 0.12 and 0.80, respectively, thereby providing a good combination of strength with toughness. In short, the fine grained ferrite and TiC precipitation strengthening contributed to a high strength.

关键词： hot rolled high strength steel TMCP (thermomechanical control process) precipitate carbide

Flame quenching process in cavity based on model scramjet combustor

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2012年第1期28卷 73-78页

作者： Yu Pan Jing Lei Jian-Han Liang Wei-Dong Liu zhen-guo wang Department of Aerospace and Material National University of Defense Technology410073 ChangshaChina

The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, To = 1483K, P0 = 1.65 MPa, T = 724 K and P -- 76.3 kPa. Changing process of the flame and shock structure in the combustor was clearly observed. The results revealed that the precom- bustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while. The time of quenching process was extended by the cavity flame holder, and the ability of flame holding was enhanced by arranging more cavities in the downstream as well. The flame was blown from the upstream to the downstream, so the flame in the downstream of the cavity was quenched out later than that in the upstream.

关键词： Flame quenching process Cavity Model scramjet combustor

High-temperature deformation behavior of a beta Ti-3.0Al-3.5Cr-2.0Fe-0.1B alloy

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2018年第3期37卷 217-224页

作者： Wen-Tao Qu Xu-Guang Sun Song-Xiao Hui zhen-guo wang Yan Li School of Mechanical Engineering Xi'an Shiyou University State Key Laboratory of Nonferrous Metals and Processes General Research Institute for Nonferrous Metals School of Materials Science and Engineering Beihang University

The high-temperature deformation behavior of a beta Ti-3.0 Al-3.5 Cr-2.0 Fe-0.1 B alloy was investigated by a Gleeble-1500 D thermal simulator. The height reduction was 50%, corresponding to a true strain of 0.693. The strain rate ranging from 0.01 to 10.00 s^-1 and the deformation temperature ranging from 800 to 950 ℃ were *** flow stress and the apparent activation energy for deformation, along with the constitutive equation, were used to analyze the behavior of the Ti-3.0 Al-3.5 Cr-2.0 Fe-0.1 B alloy. The processing map was established. The effect of strain rate on the microstructure at 850 ℃ was *** flow stress-strain curves indicated that the peak flow stresses increased along with an increase in the strain rate and decreased as the deformation temperature *** on the true stress-true strain curves, the constitutive equation was established and followed as the ε= 6.58×10-（10）[sinh（0.0113σ）]-（3.44）exp（-245481.3/RT）. The processing map exhibited the ＂unsafe＂ region at the strain rate of10 s^-1 and the temperature of 850 ℃,and the rest region was ＂safe＂. The deformation microstructure demonstrated that both dynamic recovery（DRV） and dynamic recrystallization（DRX） existed during deformation. At the lower strain rate of 0.01 s^-1, the main deformation mechanism was the DRV, and the DRX was the dominant deformation mechanism at the higher strain rate of 1.00 s^-1.

关键词： Titanium alloy Hot deformation Constitutive equation Processing map Microstructure

Tribological behaviour of biomedical Ti–Zr-based shape memory alloys

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2017年第6期36卷 478-484页

作者： Wen-Tao Qu Xu-Guang Sun Bi-Fei Yuan Kang-Ming Li zhen-guo wang Yan Li School of Mechanical Engineering Xi'an Shiyou UniversityXi'an 710065 China School of Materials Science and Engineering Beihang University Beijing 100191 China Key Laboratory of Aerospace Materials and Performance(Ministry of Education) Beihang University Beijing 100191China

The tribological behaviour of Ti-30Zr, Ti-20Zr-10Nb and Ti-19Zr-10Nb-1Fe alloys was investigated using reciprocating friction and wear tests. X-ray diffraction（XRD） results indicate that Ti-30Zr, Ti-20Zr-10Nb and Ti-19Zr-10Nb-1Fe alloys are composed of hexagonal a＇-martensite, orthorhombic a＇＇-martensite and bcc β phases,respectively. Ti-30Zr alloy has the highest hardness of HV（273.1 ± 9.3）, while Ti-20Zr-10Nb alloy exhibits the lowest hardness of HV（235.2 ± 20.4） among all the *** tribological results indicate that Ti-30Zr alloy shows the best wear resistance among these alloys, corresponding to the minimum average friction coefficient of 0.052 and the lowest wear rate of 6.4x10^-4mm3·N^-1·m^-1. Ti-20Zr-10Nb alloy displays better wear resistance than Ti-19Zr-10Nb-1Fe alloy, because the iron oxide is easy to fall off and less Nb2O5 films form on the worn surface of the *** and abrasive wear in association with adhesive wear are the main wear mechanism of these alloys.

关键词： Biomedical material Shape memory alloyTi-Zr Tribology

Design method for hypersonic bump inlet based on transverse pressure gradient

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第6期23卷 479-494页

作者： Shang-cheng XU Yi wang zhen-guo wang Xiao-qiang FAN Bing XIONG College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

Transverse pressure gradient(TPG)is one of the key factors influencing the boundary layer airflow diversion in a bump *** paper proposes a novel TPG-based hypersonic bump inlet design *** method consists of two ***,a parametric optimization approach is employed to design a series of 2D inlets with various compression ***,according to the prescribed TPG,the optimized inlets are placed in different osculating planes to generate a 3D bump *** method provides a means to directly control the aerodynamic parameters of the bump rather than the geometric *** performing this method to a hypersonic chin inlet,a long and wide bump surface is formed in the compression wall,which leads to good integration of the bump/*** show that a part of the near-wall boundary layer flow is diverted by the bump,resulting in a slight decrease in the mass flow but a significant improvement in the total pressure *** addition,the starting ability is significantly improved by adding the bump *** reveals that the bump has a 3D rebuilding effect on the large-scale separation bubble of the unstarted ***,a mass flow correction is performed on the designed bump inlet to increase the mass flow to full airflow *** results show that the mass flow rate of the corrected bump inlet reaches up to 0.9993,demonstrating that the correction method is effective.

关键词： Hypersonic bump inlet Transverse pressure gradient(TPG) Boundary layer flow Total pressure recovery Starting ability Mass flow correction

Effects of bump parameters on hypersonic inlet starting performance

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2022年第10期23卷 807-819页

作者： Shang-cheng XU Yi wang zhen-guo wang Xiao-qiang FAN Bing XIONG College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

Unstart is an unwanted flow phenomenon in a hypersonic inlet. When an unstart occurs, the captured airflow flowing through the engine significantly decreases with strong unsteady characteristics, which may lead to thrust loss or even combustor flameout. In this study, various bump configurations were designed to be integrated with a hypersonic inlet to improve its starting ability. A bump was defined as an integrated 3D compression surface installed upstream of the inlet entrance. The starting processes of these bump inlets were numerically simulated to investigate the effect laws and flow mechanisms of the bump parameters. Tests on bump height revealed that the starting performance could be significantly improved by increasing bump height, with the starting Mach number decreasing by 0.55 for the inlet with the highest bump. The high bump facilitates the side movement of the subsonic flow in the separation zone, which leads to a small separation bubble, thus accelerating the starting process. Further, the starting ability can be improved by designing a relatively wide bump, which results in a decline in the starting Mach number by 0.44. When the bump has the same or greater width compared with the airflow capture range, a growing spillage along the transverse direction can be formed so that the airflow in the separation bubble can be easily excluded, improving the starting ability.

关键词： Hypersonic inlet Bump Boundary layer flow Starting performance Large-scale separation bubble

基于数值计算方法的翼型参数化、建模与优化研究（英文）

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2016年第8期17卷 632-645页

作者： Tian-tian ZHANG Wei HUANG zhen-guo wang Li YAN Science and Technology on Scramjet Laboratory National University of Defense Technology

目的:1.比较并改善翼型参数化方法,获得设计变量少、拟合精度高的参数化方法;2.在参数化的基础上利用数值模拟的方法获取翼型流场参数,优化并获得特定条件下升阻比最大的翼型。创新点:1.通过与多项式拟合方法的对比证明了类别/形状函数... 详细信息

目的:1.比较并改善翼型参数化方法,获得设计变量少、拟合精度高的参数化方法;2.在参数化的基础上利用数值模拟的方法获取翼型流场参数,优化并获得特定条件下升阻比最大的翼型。创新点:1.通过与多项式拟合方法的对比证明了类别/形状函数转换(CST)法在翼型拟合方面的优越性,并通过调整控制点分布,在不增加设计变量的基础上改善了CST方法;2.通过建立响应面模型,利用多岛遗传算法与非线性序列二次规划法相结合的方式获得了更好的翼型优化效果。方法:1.利用修饰后的CST法对翼型进行参数化拟合与设计,并通过与二项式拟合法比较来验证其优越性;2.通过数值方法对翼型周围流场进行计算并与实验结果对比,获得精确计算气动参数的仿真条件;3.通过拉丁超立方采样获得设计变量,建立设计变量与翼型升阻比之间的响应面模型,通过多岛遗传算法与非线性序列二次规划法的结合和优化,得到一定条件下升阻比最大的翼型。结论:***法是一种优秀的参数化方法,本文的优化改善了形状函数控制点选取法则,使其对翼型头部和尾部的描述更加精确;与多项式相比,CST法可以通过更少的设计变量得到更高的拟合精度。2.基于多岛遗传算法的非线性序列二次规划法在本文中用以优化翼型使其具有更高升阻比。优化前后翼型的比较显示,两种优化方法的结合可以得到比单独使用各优化方法更好的结果。

关键词：类别/形状函数转换参数化数值仿真响应面模型优化翼型设计