检索结果-南通市图书馆

Prospects of sea launches for Chinese cryogenic liquid-fueled medium-lift launch vehicles

维普期刊数据库评论

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 2021年第1期34卷 424-437页

作者： Zhengyu SONG Zhifeng XIE limin qiu Dalin XIANG Jinglin LI China Academy of Launch Vehicle Technology Beijing 100076China Beijing Institute of Astronautical Systems Engineering Beijing 100076China College of Energy Engineering Zhejiang UniversityHangzhou 310027China

This paper introduces the sea-launch technology of a cryogenic liquid-fueled medium-lift *** first reviews the current state of sea launch technology,and then gives a brief introduction of China’s New Generation Medium-lift Launch Vehicle(NGMLV).The innovations in the NGMVL,such as responsive test and launch control,a H3 launch model,and unmanned operations,provide convenience for sea *** on these innovations,this paper proposes a sea launch scheme,including the system configuration,test and launch processes,and an improved adaptive design for the ***,the launch platform is discussed in detail,which integrates the functions of sea transportation,assembly and test,as well as technical and launch *** layout and function divisions,fluid filling,gas supply and distribution systems,and lossless storage technology of LH2 are described in *** breakthrough in sea launch technology will enable China to launch medium and large satellites and constellations‘both on land and sea’,especially into low-inclination Low-Earth Orbits(LEOs),and it allows China to remain competitive in the fast-paced space industry.

关键词： Autonomous operations Launch platform Launch vehicles Liquid hydrogen storage Sea launches

Modeling cavitation flow of cryogenic fluids with thermodynamic phase-change theory

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2013年第4期58卷 567-574页

作者： ZHANG XiaoBin WU Zhao XIANG ShiJun qiu limin Institute of Refrigeration and Cryogenic Engineering Zhejiang University

Cavitation is the formation of vapor bubbles within a liquid where the flow dynamics causes the local static pressure to drop below the vapor pressure. The so-called full cavitation model (FCM) developed by Singhal has been widely used in numerical modeling of the cavitation flow for thermosensible and non-thermosensible fluids. Within the FCM, the bubble size is taken to be equivalent to the maximum possible value to forego the calculation of bubble number density. We developed a new cavitation model by recalculating the bubble radius in FCM to account for the effects of local pressure. The new model was obtained by combining the thermodynamic phase-change theory and the Young-Laplace equation with the assumption of thermodynamic equilibrium during the cavitation process. The cavitation calculations were performed based on the mathematical framework of the homogeneous equilibrium flow model and the transport-equation-based model for vapor phase mass fraction. The model was validated by modeling the cavitating flow of liquid nitrogen and liquid hydrogen through NASA hydrofoil and Ogive with consideration of the phase-change thermal effects. The temperature and pressure distributions with the new model are found to agree well with data from existing experimental studies, as well as the simulations with the FCM.

关键词：空化流动热力学理论相变理论低温液体建模热力学平衡空化模型气泡半径

Investigation on regenerator temperature inhomogeneity in Stirling-type pulse tube cooler

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2009年第6期54卷 986-991页

作者： SUN DaMing MARC Dietrich GUENTER Thummes qiu limin Institute of Refrigeration and Cryogenics of Zhejiang University Hangzhou 310027 China Institute of Applied Physics University of Giessen Giessen D-35392 Germany TransMIT-Centre for Adaptive Cryotechnology and Sensors Germany

Regenerator is one of the most crucial components to pulse tube cooler (PTC) and thermoacoustic engine. As such regenerator is scaled up to high-power, the thermal and hydrodynamic communication transverse to the acoustic axis gets weaker and weaker. Under this condition, any unsymmetric factor could cause serious instability to the cooler or engine, which degrades their performance. Investigation has been carried out on a high-power two-stage thermal-coupled U-shape Stirling-type PTC. By detailed circumferential temperature measurements along the middle heat exchanger and second stage regen-erator, a kind of temperature inhomogeneity caused by unsymmetric pre-cooling effect of inter-stage thermal bridge was found in the lower part of the regenerator of the PTC. The temperature inhomoge-neity originating from the middle heat exchanger of the second stage regenerator amplified itself in the lower part of the regenerator and then internal streaming formed. The maximal radial temperature dif-ference could reach 30―40 K. Experimental results show that the temperature inhomogeneity intensi-fies with increased pre-cooling power and its direction can be reversed by changing the pre-cooling effect of the first stage PTC to heating effect by using external thermal load. This research shows that it is important to maintain the heating or cooling effects of heat exchangers uniform in high-power re-generative coolers and engines.

关键词：再生温度不均匀性脉管制冷机林型 PTC公司热声发动机中间换热器冷却效果

Effects of surface tension on bubble growth in an extensive uniformly superheated liquid

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2011年第30期56卷 3191-3198页

作者： ZHANG XiaoBin XIANG ShiJun CAO XiaoLi qiu limin Institute of Refrigeration and Cryogenics Zhejiang University Hangzhou 310027 China

The study of bubble growth in an extensive pool of liquid provides considerable insight into the mechanisms that play a role in bubble growth near a heated surface and in the cavitation phenomenon. This work focuses on analyzing the effects of surface tension on the growth rate for the thermally controlled stage of a single bubble in such a liquid. The conservation of energy equations, including the internal energy term for the bubble and that within boundary layer around it, are numerically solved. The complete temporal variations of the bubble in water and liquid nitrogen are investigated based on the assumption that the bubble growth is controlled only in sequence by inertia and heat. Thus, the two stages are subject to the continuity of the bubble growth, while the inertia-controlled stage is only formulated by the well-known Rayleigh solution. The thickness of the boundary layer around the bubble is also determined. The results are comparable with the Plesset-Zwick models and Forster-Zuber models, as well as available experimental data. It is found that the influence of internal energy on the rate of bubble growth is small enough to be ignored; however, the accumulative effects of the surface tension are significant and increase with a decrease in the degree of superheat.

关键词：表面张力气泡生长过热度液体均匀能量方程惯性控制泡沫层

Validation of dynamic cavitation model for unsteady cavitating flow on NACA66

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2014年第4期57卷 819-827页

作者： ZHANG XiaoBin ZHANG Wei CHEN JianYe qiu limin SUN DaMing Institute of Refrigeration and Cryogenics Zhejiang University

Unsteady cavitating flow is extremely complicated and brings more serious damages and unignorable problems compared with steady cavitating *** has become a practical way to model cavitation;however,the popularly used full cavitation model cannot reflect the pressure-change that the bubble experiences during its life path in the highly unsteady flow like cloud *** a dynamic cavitation model(DCM)is proposed and it has been considered to have not only the first-order pressure effects but also zero-order effect and can provide greater insight into the physical process of bubble producing,developing and collapsing compared to the traditional cavitation *** has already been validated for steady cavitating flow,and the results were ***,DCM is designed and supposed to be more accurate and efficient in modeling unsteady cavitating flow,which is also the purpose of this *** basic characteristic of the unsteady cavitating flow,such as the vapor volume fraction distribution and the evolution of pressure amplitude and frequency at different locations of the hydrofoil,are carefully studied to validate *** is found that not only these characteristics mentioned above accord well with the experimental results,but also some detailed transient flow information is depicted,including the re-entrant jet flow that caused the shedding of the cavity,and the phenomenon of two-peak pressure fluctuation in the vicinity of the cavity closure in a *** numerical results validate the capability of DCM for the application of modeling the complicated unsteady cavitating flow.

关键词： unsteady cavitation dynamical cavitation model NACA66 hydrofoil

Validation of full cavitation model in cryogenic fluids

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2009年第10期54卷 1633-1640页

作者： CAO XiaoLi ZHANG XiaoBin qiu limin GAN ZhiHua Institute of Refrigeration and Cryogenics Zhejiang University Hangzhou 310027 China

Numerical simulation of cavitation in cryogenic fluids is important in improving the stable operation of the propulsion system in liquid-fuel rocket. It also represents a broader class of problems where the fluid is operating close to its critical point and the thermal effects of cavitation are pronounced. The present article focuses on simulating cryogenic cavitation by implementing the "full cavitation model", coupled with energy equation, in conjunction with iterative update of the real fluid properties at local temperatures. Steady state computations are then conducted on hydrofoil and ogive in liquid nitrogen and hydrogen respectively, based on which we explore the mechanism of cavitation with thermal effects. Comprehensive comparisons between the simulation results and experimental data as well as previous computations by other researchers validate the full cavitation model in cryogenic fluids. The sensitivity of cavity length to cavitation number is also examined.

关键词：空化模型低温液体验证数值模拟低温流体稳态计算液体燃料推进系统

Study on the onset temperature of a standing-wave thermoacoustic engine based on circuit network theory

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2012年第10期55卷 2864-2868页

作者： qiu limin LAI BiHui ZHAO YiTao SUN DaMing ZHANG XueJun LI YanFeng Institute of Refrigeration and Cryogenics Zhejiang UniversityHangzhou 310027China

Onset mechanism is one of the most fundamental issues in thermoacoustic ***,the onset conditions and the phenomena happening in the onset process have not been well explained *** this paper,a novel model based on the circuit network analogy is proposed to predict the onset temperature of a standing-wave thermoacoustic *** activity and instability criteria are proposed to be the onset criteria in the *** influences of the porosity of the heat exchanger and the stack,and the length of the resonant tube on the onset temperature are *** calculated results are in agreement with the experimental results,which indicates that the activity and instability criteria can be used to predict the onset conditions of a thermoacoustic engine.

关键词： standing-wave thermoacoustic engine activity criterion instability criterion onset temperature

Characteristics of onset and damping in a standing-wave thermoacoustic engine driven by liquid nitrogen

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2013年第11期58卷 1325-1330页

作者： qiu limin LOU Ping WANG Kai WANG Bo SUN DaMing RAO JunFeng ZHANG XueJun Institute of Refrigeration and Cryogenics Zhejiang University The 16th Research Institute of China Electronics Technology Group Hefei 230043 China

We explore characteristics of onset and damping in a thermoacoustic engine (TE) driven by cryogens instead of conventional heat sources above the ambient temperature by a comprehensive study of a self-made standing-wave thermoacoustic engine driven by liquid nitrogen. The experiments verify the feasibility of enhancing the thermoacoustic oscillation at cryogenic temperatures. The onset temperature difference along the stack of the TE significantly decreases, compared with that of a conventional TE driven by high-temperature heat sources. The resonance frequency of the cryogen-driven TE is smaller than that of the heat-source-driven TE, mainly due to the lower average temperature of the working gas. Experiments and calculations show that the temperature discrepancy between onset and damping is partly caused by the linear temperature distribution along the stack before damping, together with the nonlinear distribution before onset. These results will contribute to a better understanding of thermoacoustic oscillation and to the recovery of the cold energy of cryogens.

关键词：热声发动机阻尼特性源驱动发病驻波液氮非线性分布热声振荡

Exhaust process of cryogenic nitrogen gas from a cryogenic wind tunnel with an inclined exit

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) 2023年第5期24卷 419-431页

作者： Jingfeng LI Kai WANG Chenjie GU limin qiu Institute of Refrigeration and Cryogenics Zhejiang UniversityHangzhou 310027China Baima Lake Laboratory Hangzhou 310051China

A new structural design for the vent stack with an inclined exit was proposed to reduce the settlement hazard of the cryogenic plume from a cryogenic wind tunnel;it extends the plume trajectory to increase the effective contact space and time for mixing between the plume gas and atmospheric air before the plume settles to the ground,contributing to more efficient energy consumption for ***-scale experiments and numerical simulations of plume dispersion based on vertical and 30°-and 45°-inclined exits were conducted to study harm reduction and energy-saving *** of the minimum temperature and minimum oxygen concentration of the plume near the ground indicate that the new exhaust design with an inclined exit clearly reduces the settlement *** windless conditions and without using a fan-ejector system,up to 15.9%of the heating energy used by the burner can be saved by adopting the new design.

关键词： Cryogenic gas dispersion Cryogenic wind tunnel Exhaust method Hazard reduction Inclined exit