检索结果-南通市图书馆

Topological study about failure behavior and energy absorption of honeycomb structures under various strain rates

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第6期24卷 214-227页

作者： Yu-chen Wei Meng-jie Tian Chun-yang Huang Shao-wu Wang Xing Li Qian-ran Hu Meng-qi Yuan State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100036China Chongqing Innovation Center Beijing Institute of TechnologyChongqing400044China State Grid Anhui Electric power research institute Hefei230601China

High-speed impact threats and terrorist actions on the battlefield require the development of more effective protective materials and structures,and various protective structure is designed according their energy-absorbing *** this research,the deformation behavior,microscopic failure modes and energy absorption characteristics of re-entrant hexagonal structure,regular hexagonal structure and regular quadrilateral structure are studied under different strain rates *** re-entrant hexagonal structure forms a“X”-shaped deformation zone,the regular quadrilateral and regular hexagonal structure form an“I”-shaped deformation *** microscopic appearance of the section is a mixed fracture *** effects of the topological shape,cell angle,and cell height on the impact behavior of the structure were *** the cell height is fixed and the cell angle is changed,the energy absorption of the structure increase and then decrease as the relative density *** mechanical properties of the structure are optimal when the relative density is about 18.6%and the cell angle is22.5°.When the cell angle is fixed and the cell height is changed,as the relative density increases,the energy absorption of the structure gradually *** regular quadrilateral structure and the reentrant hexagonal structure experienced clear strain rate effects under dynamic impact conditions;the regular hexagonal structure did not exhibit obvious strain rate *** results presented herein provide a basis for further rational design and selection of shock-resistant protective structures that perform well in high-speed impact environments.

关键词： Honeycomb structures Impact loading Negative Poisson's ratio Titanium alloy Dynamic response

Data-driven Inverter-based Volt/VAr Control for Partially Observable Distribution Networks

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of power and Energy Systems 2023年第2期9卷 548-560页

作者： Tong Xu Wenchuan Wu Yiwen Hong Junjie Yu Fazhong Zhang Southwest Electric power design institute Co. Ltd.of China Power Engineering Consulting GroupChengduSichuan 610021China Tsinghua University Beijing 100084China Department of Electrical Engineering State Key Laboratory of Power SystemsTsinghua UniversityBeijing 100084China Guangdong power Grid Zhongshan power Supply Bureau Zhongshan 528400China

For active distribution networks(ADNs)integrated with massive inverter-based energy resources,it is impractical to maintain the accurate model and deploy measurements at all nodes due to the large-scale of ***,current models of ADNs usually involve significant errors or even unknown ***,ADNs are usually partially observable since only a few measurements are available at pilot nodes or nodes with significant *** provide a practical Volt/Var control(VVC)strategy for such networks,a data-driven VVC method is proposed in this ***,the system response policy,approximating the relationship between the control variables and states of monitoring nodes,is estimated by a recursive regression closed-form ***,based on real-time measurements and the newly updated system response policy,a VVC strategy with convergence guarantee is *** the recursive regression solution is embedded in the control stage,a data-driven closedloop VVC framework is *** effectiveness of the proposed method is validated in an unbalanced distribution system considering nonlinear loads,where not only the rapid and self-adaptive voltage regulation is realized,but also systemwide optimization is achieved.

关键词： Data-driven distribution networks partial observation Volt/VAr control

Data network traffic analysis and optimization strategy of real-time power grid dynamic monitoring system for wide-frequency measurements

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Global Energy Interconnection 2022年第2期5卷 131-142页

作者： Jinsong Li Hao Liu Wenzhuo Li Tianshu Bi Mingyang Zhao State Key Lab of Alternate Electric power System with Renewable Energy Sources(North China Electric power University) Beijing 102206P.R.China beijing Key Laboratory of research and System Evaluation of power Dispatching Automation Technology(China Electric power research institute) Beijing 100192P.R.China

The application and development of a wide-area measurement system(WAMS)has enabled many applications and led to several requirements based on dynamic measurement *** data are transmitted as big data information *** ensure effective transmission of wide-frequency electrical information by the communication protocol of a WAMS,this study performs real-time traffic monitoring and analysis of the data network of a power information system,and establishes corresponding network optimization strategies to solve existing transmission *** study utilizes the traffic analysis results obtained using the current real-time dynamic monitoring system to design an optimization strategy,covering the optimization in three progressive levels:the underlying communication protocol,source data,and transmission *** of the system structure and scheduling optimization of data information are validated to be feasible and practical via tests.

关键词： power system Data network Wide-frequency information Real-time system Traffic analysis Optimization strategy

A three-dimensional inverse method based on moving no-slip boundary for profiled end wall design

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2024年第10期37卷 221-233页

作者： Hanwen GUO Donghai JIN Jiancheng ZHANG Xingmin GUI School of Energy and power Engineering Beihang UniversityBeijing 100191China Jiangxi research institute of Beihang University Nanchang 330096China

How to utilize existing flow control mechanisms to make profiled end wall design more flexible,efficient,and physical is a meaningful *** study presents a three-dimensional inverse method for profiled end wall design to achieve the application of flow control *** predetermined pressure distribution on the end wall is reached by modifying the end wall geometry during flow field calculation.A motion velocity model is derived from the normal momentum equation of the moving no-slip boundary to modify the end wall geometry.A Reynolds-Averaged Navier-Stokes(RANS)solver based on the Semi-Implicit Method for Pressure Linked Equations(SIMPLE)algorithm is adopted to simulate the flow *** on the mechanism understanding obtained through numerical optimization results,this study adopts the inverse method to redesign an optimized end wall in a compressor *** results indicate that the redesigned end wall exhibits better loss reduction,reducing the overall total pressure loss by 5.5%,whereas the optimized end wall reduces it by 3%.The inverse method allows the imposition of desired influences on the end wall flow without constructing a database,making it highly flexible,efficient,and physical.

关键词： Compressor Flow control Corner separation Profiled end wall Inverse method

Blade bowing effects on radial equilibrium of inlet flow in axial compressor cascades

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2017年第5期30卷 1651-1659页

作者： Han XU Hao CHANG Donghai JIN Xingmin GUI School of Energy and power Engineering Beihang University Beijing 100083 China AECC Shenyang Engine research institute Shenyang 110015 China

The circumferentially averaged equation of the inlet flow radial equilibrium in axial compressor was deduced. It indicates that the blade inlet radial pressure gradient is closely related to the radial component of the circumferential fluctuation（CF） source item. Several simplified cascades with/without aerodynamic loading were numerically studied to investigate the effects of blade bowing on the inlet flow radial equilibrium. A data reduction program was conducted to obtain the CF source from three-dimensional（3D） simulation results. Flow parameters at the passage inlet were focused on and each term in the radial equilibrium equation was discussed quantitatively. Results indicate that the inviscid blade force is the inducement of the inlet CF due to geometrical asymmetry. Blade bowing induces variation of the inlet CF, thus changes the radial pressure gradient and leads to flow migration before leading edge（LE） in the cascades. Positive bowing drives the inlet flow to migrate from end walls to mid-span and negative bowing turns it to the reverse direction to build a new equilibrium. In addition, comparative studies indicate that the inlet Mach number and blade loading can efficiently impact the effectiveness of blade bowing on radial equilibrium in compressor design.

关键词： Axial compressor Bowing Cascade Circumferential fluctuation Inlet flow Radial equilibrium

Non-synchronous blade vibration analysis of a transonic fan

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2023年第1期36卷 178-190页

作者： Yun ZHENG Qingzhe GAO Hui YANG School of Energy and power Engineering Beihang UniversityBeijing 100191China Jiangxi research institute Beihang UniversityNanchang 330096China

This study numerically investigates the aeromechanic behavior of a transonic fan model with a flat tip-leading-edge on the NASA rotor 67 test ***-passage unsteady calculations at a near stall operating point of 82%design speed show that the dominant frequencies of mass flow were not the harmonics of the rotor rotational frequency.A full-annulus fluid–structure interaction analysis was subsequently carried out to examine the unsteady flows and their interactions with blade *** results show that the modal displacement of the backward traveling seventh nodal diameter of the second torsion mode grew exponentially,which reveals that the blade vibration was *** vibration pattern indicates that the aerodynamic mode was resonant with the structural vibration *** the rotor tip,the circumferential vortical propagation induced by interactions among the main flow,tip leakage flow,and tip clearance vortex was the source of aerodynamic *** clarify the mechanism of the non-synchronous vibration,the coupling between aerodynamic disturbance and structural response,i.e.,aliasing,was *** frequency spectra of the fluctuating pressure show that an aerodynamic Back-ward Traveling Wave(BTW)was co-aliased to a structural BTW due to the propagation of the cir-cumferential *** correlation between the frequency and free convective speed of the aerodynamic disturbance determined the directions of aliasing.

关键词： Aerodynamic disturbance Aliasing Blade vibration Circumferential vortical propagation Traveling wave

How the radial gap affects the runner’s hydrodynamic damping characteristic of a pump-turbine:A physical experiment on a rotating disc

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2023年第4期35卷 736-745页

作者： Yong-shun Zeng Xin Qi Mian-mian Bai Ling-jiu Zhou Zhi-feng Yao College of Water Resources and Civil Engineering China Agricultural UniversityBeijing100083China BAPTEEC LTD Beijing100176China Shanxi Province institute of Water Resources and Electric power Investigation and design Xi’an710001China beijing Engineering research Center of Safety and Energy Saving Technology for Water Supply Network System Beijing100083China

Clarifying how radial gap affects the vibration characteristic of a disc-like structure is of importance in engineering applications,such as in evaluating the operational stability of a runner of a pump *** the present investigation,the runner is simplified as a disc,and a physical experiment is designed on it with variable radial gaps to measure the vibration characteristics,especially by considering *** frequency peaks for the diametrical mode are generated due to the rotation,and those with lower and higher frequencies are defined as positive and negative modes,*** frequency difference between positive and negative modes increases linearly with the increasing rotating speed,and a linear function is captured to describe the relationship between natural frequency and rotating *** the radial gap,its increase causes a slight increase in the natural frequencies but results in a significant reduction in the hydrodynamic damping *** in the smaller radial gap conditions,such as when the relative radial gap increases from 0.67%to 3.3%,the reduction in hydrodynamic damping ratio reaches 31.52%.From the perspective of suppressing the resonance amplitude,reducing the radial gap of a runner is recommended due to the mechanism of increasing hydrodynamic damping.

关键词： Rotating disc radial gap rotating speed natural frequency hydrodynamic damping

The Single-active-part Structure of the UHVDC Converter Transformer with the UHVAC power Grid

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

CSEE Journal of power and Energy Systems 2017年第3期3卷 243-252页

作者： Yun Liu Guangfan Li Lan Guan Zhi Li State Key Laboratory of Alternate Electrical power System with Renewable Energy Sources(North China Electric power University) Beijing 102206China UHV Department(State Grid Brazil Holding S.A.) Rio de Janeiro 20071004Brazil UHV research institute(Electric power research institute of China) Beijing 100092China Electric power research institute of China Beijing 100092China State power Economic research institute Beijing 100028China Shenyang Transformer research institute Shenyang 110179China

The studied sending-terminal’s UHVDC converter transformer with the UHVAC grid is currently one of the largest-capacity converter transformers,which is characterized by strong support for the large-scale grid power delivering out,strengthening grid’s fault tolerance and backup capability,improving grid operation’s flexibility and security,lowering the short-circuit *** proposed single-active-part converter transformer structure is well-designed,including the single-phase five-leg iron core,the special winding arrangement,the special structure of the spacers and angle rings,and so on,which is a smaller footprint,easier to install and test on site,but is more challenging in the structural design due to the critical railway transportation limitations on aspects of both size and *** feasibility of the proposed structure schema is verified by a series of tests,concerning the wave process,the short circuit force,the temperature field,the main insulation,and so *** them,the main insulation’s electric fields at the import positions are verified to be reasonable,including the AC impressed voltage test,the DC impressed voltage test,and the polarity reversal *** shows that the proposed single-active-part design scheme is practicable and conductive to manufacture and application for the UHV large-capacity converter transformers.

关键词： Converter transformer electric field singleactive-part structural design UHVAC UHVDC test

A multi-fidelity simulation method research on front variable area bypass injector of an adaptive cycle engine

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第4期35卷 202-219页

作者： Zhewen XU Ming LI Hailong TANG Min CHEN School of Energy and power Engineering Beihang UniversityBeijing 100083China Aero Engine Academy of China Beijing 101300China research institute of Aero-Engine Beihang UniversityBeijing 102206China

Front Variable Area Bypass Injector(Front-VABI) is a component of the Adaptive Cycle Engine(ACE) with important variable-cycle features. The performance of Front-VABI has a direct impact on the performance and stability of ACE, but the current ACE performance model uses approximate models for Front-VABI performance calculation. In this work, a multi-fidelity simulation based on a de-coupled method is developed which delivers a more accurate calculation of the Front-VABI performance based on Computational Fluid Dynamics(CFD) simulation. This simulation method proposes a form of Front-VABI characteristic and its matching calculation method between it and the ACE performance model, constructs a coupling method between the(2-D) Front-VABI model and the(0-D) ACE performance model. The result shows, when ACE works in triple bypass mode, the approximate model cannot account for the effect of FrontVABI pressure loss on Core Driven Fan Stage(CDFS) design pressure ratio, and the calculated error of high-pressure turbine inlet total temperature is more than 40 K in mode transition condition(the transition operating condition between triple bypass mode and double bypass mode). In double bypass mode, the approximate model can better simulate the performance of FrontVABI by considering the local loss of area expansion. This method can be applied to the performance-optimized design of Front-VABI and the ACE control law design during mode transition.

关键词： Adaptive cycle engine Computational fluid dynamics Front variable area bypass injector Multi-fidelity simulation Performance model