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Numerical study on natural convection in a square enclosure containing a rectangular heated cylinder

Jianhua LU, Zhaoli GUO, Zhenhua CHAI, Baochang SHI,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 373-380 doi: 10.1007/s11708-009-0078-x

摘要: In this paper, the natural convection in a square enclosure with a rectangular heated cylinder is investigated via the lattice Boltzmann method. A detailed study is conducted on the effect of the cylinder width and the Rayleigh number on the fluid flow and heat transfer. The flow structures and heat transfer patterns are classified into eight buoyant regimes, i.e., four steady regimes, two periodic regimes, one multiple periodic regime, and one chaos regime, two of which are reported for the first time.

关键词: natural convection     buoyant regime     heated cylinder     lattice Boltzmann    

A pneumatic cylinder driving polyhedron mobile mechanism

Wan DING, Sung-Chan KIM, Yan-An YAO

《机械工程前沿(英文)》 2012年 第7卷 第1期   页码 55-65 doi: 10.1007/s11465-012-0301-z

摘要:

A novel pneumatic cylinder driving polyhedron mobile mechanism is proposed in this paper. The mechanism is comprised of 5 tetrahedrons which includes a pneumatic cylinder in each edge. It locomotes by rolling and the rolling principle refers to the center of mass (CM) of the mechanism moved out of the supporting area and let it tip over through the controlling of the motion sequence of these cylinders. Firstly, the mathematical model is built to analysis the relation between the configuration and the CM of the mechanism. Then, a binary control strategy is developed to simplify and improve the control of this mobile mechanism. After that, dynamic simulation is performed to testify the analytical validity and feasibility of the rolling gaits. At last, a prototype is fabricated to achieve the rolling successfully to demonstrate the proposed concept.

关键词: mobile mechanism     polyhedron     cylinder    

Thermodynamic models and energy distribution of single-phase heated surface in a boiler under unsteady

Xiyan GUO, Yongping YANG

《能源前沿(英文)》 2011年 第5卷 第1期   页码 69-74 doi: 10.1007/s11708-010-0117-7

摘要: A coal-fired power unit frequently operates under unsteady conditions; thus, in order to acquire scientific energy analysis of the unit, thermodynamic analysis of a single-phase heated surface in a boiler under such conditions requires investigation. Processes are analyzed, and distributions of energy and exergy are qualitatively revealed. Models for energy analysis, entropy analysis, and exergy analysis of control volumes and irreversible heat transfer processes are established. Taking the low-temperature superheater of a 610 t/h-boiler as an example, the distribution of energy, entropy production, and exergy is depicted quantitatively, and the results are analyzed.

关键词: thermodynamic model     energy distribution     boiler     unsteady conditions    

A numerical study of helium-heated inorganic membrane reformer coupling to HTGR

YIN Huaqiang, JIANG Shengyao, JU Huaiming, ZHANG Youjie

《能源前沿(英文)》 2007年 第1卷 第4期   页码 446-450 doi: 10.1007/s11708-007-0065-3

摘要: Based on one-dimensional quasi-homogeneous model, a steady-state model and its computer program were developed for helium-heated inorganic membrane reformer coupling to high temperature gas-cooled reactor (HTGR). The results show

关键词: temperature gas-cooled     one-dimensional quasi-homogeneous     steady-state     helium-heated    

Enhancing fatigue life of cylinder-crown integrated structure by optimizing dimension

Weiwei ZHANG,Xiaosong WANG,Zhongren WANG,Shijian YUAN

《机械工程前沿(英文)》 2015年 第10卷 第1期   页码 102-110 doi: 10.1007/s11465-015-0329-y

摘要:

Cylinder-crown integrated hydraulic press (CCIHP) is a new press structure. The hemispherical hydraulic cylinder also functions as a main portion of crown, which has lower weight and higher section modulus compared with the conventional hydraulic cylinder and press crown. As a result, the material strength capacity is better utilized. During the engineering design of cylinder-crown integrated structure, in order to increase the fatigue life, structural optimization on the basis of the adaptive macro genetic algorithms (AMGA) is first conducted to both reduce weight and decrease peak stress. It is shown that the magnitude of the maximum principal stress is decreased by 28.6%, and simultaneously the total weight is reduced by 4.4%. Subsequently, strain-controlled fatigue test is carried out, and the stress-strain hysteresis loops and cyclic hardening curve are obtained. Based on linear fit, the fatigue properties are calculated and used for the fatigue life prediction. It is shown that the predicted fatigue life is significantly increased from 157000 to 1070000 cycles after structural optimization. Finally, according to the optimization design, a 6300 kN CCIHP has been manufactured, and priority application has been also suggested.

关键词: cylinder-crown integrated hydraulic press (CCIHP)     adaptive macro genetic algorithms (AMGA)     strain-controlled fatigue test    

Antifungal and antibacterial functions of medicinal leech recombinant destabilase-lysozyme and its heated-up

T. G. YUDINA, Danyang GUO, N. F. PISKUNKOVA, I. B. PAVLOVA, L. L. ZAVALOVA, I. P. BASKOVA

《化学科学与工程前沿(英文)》 2012年 第6卷 第2期   页码 203-209 doi: 10.1007/s11705-012-1277-2

摘要: Antifungal activity of recombinant medicinal leech destabilase-lysozyme (rec.Dest-Lys) was investigated by using fungi: , and , including yeasts and . Its antibacterial activity was investigated on gram-negative bacteria . These activities were assessed by radial agar diffusion assay, and scanning and transmission electron microscopy. Therefore, destabilase-lysozyme not only is endo-isopeptidase and lysozyme, but also has antifungal and antibacterial activities. Muramidase activity of rec.Dest-Lys disappeared after heat-treating at 90°C for 50 min without the loss of its antimicrobial activity. Furthermore we showed for the first time that the heated-up derivative of rec.Dest-Lys exhibited more potent activities against the above enumerated fungi and gram-negative bacteria than original protein.

关键词: recombinant destabilase-lysozyme (rec.Dest-Lys)     antimicrobial activity     antifungal activity     medicinal leech     heated-up derivative of rec.Dest-Lys (T-rec.Dest-Lys)    

Convective mass transfer from a horizontal rotating cylinder in a slot air jet flow

Hongting MA , Dandan MA , Na YANG ,

《能源前沿(英文)》 2009年 第3卷 第3期   页码 289-296 doi: 10.1007/s11708-009-0019-8

摘要: The effects of air jet impinging on the mass transfer characteristics from a rotating spinning cylinder surface were experimentally investigated. The effects of rotational Reynolds number

关键词: air jet impinging     rotating cylinder     critical point     mass transfer characteristics    

Unified solution of limit loads of thick wall cylinder subject to external pressure considering strain

CHEN Changfu, XIAO Shujun, YANG Yu

《结构与土木工程前沿(英文)》 2007年 第1卷 第3期   页码 329-333 doi: 10.1007/s11709-007-0043-x

摘要: Based on the unified strength theory [1], a unified strength criterion for strain softening materials, such as concrete or rock, was derived, and the elastic and plastic limit loads of a thick-walled cylinder made of these materials subject to external pressure were also given. In addition, the influence of some factors on the limit loads of such cylinders as the ratio of the external radius to internal radius,/, the coefficient , which reflects the effect of medium principal stress and the normal stress of the relevant surface on the material destroy degree, the ratio of tensile strength to compressed strength of the material, , and the damage variable

Refined analysis of axi-symmetric circular cylinder in the axial magnetic field without ad hoc assumption

Baosheng ZHAO, Yang GAO, Yingtao ZHAO, Dechen ZHANG

《机械工程前沿(英文)》 2011年 第6卷 第3期   页码 318-323 doi: 10.1007/s11465-011-0232-0

摘要:

The refined theory for axi-symmetric magnetoelastic circular cylinder is deduced systematically and directly from linear magnetoelasticity theory. Based on the general solution of magnetoelastic equation and the Lur’e method, the refined theory yields the solutions for magnetoelastic circular cylinder without ad hoc assumptions. On the basis of the refined theory developed in the present study, solutions are obtained for magnetoelastic circular cylinder with homogeneous and non-homogenous boundary conditions, respectively. For the circular cylinder with homogeneous boundary conditions, the refined theory provides exact solutions that satisfy all of the governing equations. The exact solutions can be divided into three parts: the 2-orders equation, the transcendental equation, and the magnetic equation. In the case of non-homogenous boundary conditions, the approximate governing equations are accurate up to the high-order terms with respect to cylinder radius.

关键词: refined analysis     axially symmetric deformation     circular cylinder     Bessel’s function     axial magnetic field    

Hydraulic fracturing pressure of concentric double-layered cylinder in cohesive soil

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 937-947 doi: 10.1007/s11709-021-0754-4

摘要: This study aims to investigate hydrofracturing in double-layered soil through theoretical and experimental analysis, as multilayered soils where the difference in mechanical properties exists are generally encountered in practical engineering. First, an analytical solution for fracturing pressure in two different concentric regions of soil was presented based on the cavity expansion theory. Then, several triaxial hydraulic fracturing tests were carried out to validate the analytical solution. The comparison between the experimental and analytical results indicates the remarkable accuracy of the derived formula, and the following conclusions were also obtained. First, there is a linear relationship between the fracturing pressure and confining pressure in concentric double-layered cohesive soil. Second, when the internal-layer soil is softer than the external-layer soil, the presence of internal soil on the fracturing pressure approximately brings the weakening effect, and the greater strength distinction between the two layers, the greater the weakening effect. Third, when the internal-layer soil is harder than the external-layer soil, the existence of the internal-layer soil has a strengthening effect on the fracturing pressure regardless of the proportion of internal-layer soil. Moreover, the influence of strength distinction between the two layers on the fracturing pressure is significant when the proportion of internal-layer soil is less than half, while it’s limited when the proportion is more than half. The proposed solution is potentially useful for geotechnical problems involving aspects of cohesive soil layering in a composite formation.

关键词: hydraulic fracturing pressure     layered     cavity expansion theory     triaxial fracturing test     cohesive soil    

Effect of heat transfer space non-uniformity of combustion chamber components on in-cylinder heat transfer

Jizu LV, Minli BAI, Long ZHOU, Jian ZHOU,

《能源前沿(英文)》 2010年 第4卷 第3期   页码 392-401 doi: 10.1007/s11708-009-0066-1

摘要: Combustion chamber components (cylinder head-cylinder liner-piston assembly-oil film) were treated as a coupled body. Based on the three-dimensional numerical simulation of the heat transfer of the coupled body, a coupled three-dimensional calculation model for the in-cylinder working process and the combustion chamber components was built with domain decomposition and boundary coupling method, which adopts the coupled three-dimensional simulation of in-cylinder working process and the combustion chamber components. The model was applied in the investigation of the influence of space non-uniformity in heat transfer among combustion chamber components on in-cylinder heat transfer. The results show that the effect of wall temperature space non-uniform distribution of combustion chamber components on heat transfer happens mainly at the end of the compression stroke and expansion stroke. Therefore, it can be concluded that wall temperature space non-uniform distribution of combustion chamber components would influence heat transfer during the intake and exhaust stroke obviously.

关键词: heat transfer     space non-uniformity     soot emission     in-cylinder     diesel    

Combustion and emissions of RP-3 jet fuel and diesel fuel in a single-cylinder diesel engine

《能源前沿(英文)》 2023年 第17卷 第5期   页码 664-677 doi: 10.1007/s11708-021-0787-3

摘要: The combustion characteristics and emission behaviors of RP-3 jet fuel were studied and compared to commercial diesel fuel in a single-cylinder compression ignition (CI) engine. Engine operational parameters, including engine load (0.6, 0.7, and 0.8 MPa indicating the mean effective pressure (IMEP)), the exhaust gas recirculation (EGR) rate (0%, 10%, 20%, and 30%), and the fuel injection timing (−20, −15, −10, and −5 ° crank angle (CA) after top dead center (ATDC)) were adjusted to evaluate the engine performances of RP-3 jet fuel under changed operation conditions. In comparison to diesel fuel, RP-3 jet fuel shows a retarded heat release and lagged combustion phase, which is more obvious under heavy EGR rate conditions. In addition, the higher premixed combustion fraction of RP-3 jet fuel leads to a higher first-stage heat release peak than diesel fuel under all testing conditions. As a result, RP-3 jet fuel features a longer ignition delay (ID) time, a shorter combustion duration (CD), and an earlier CA50 than diesel fuel. The experimental results manifest that RP-3 jet fuel has a slightly lower indicated thermal efficiency (ITE) compared to diesel fuel, but the ITE difference becomes less noticeable under large EGR rate conditions. Compared with diesel fuel, the nitrogen oxides (NOx) emissions of RP-3 jet fuel are higher while its soot emissions are lower. The NOx emissions of RP-3 can be effectively reduced with the increased EGR rate and delayed injection timing.

关键词: RP-3 jet fuel     diesel     engine     combustion     emissions    

柴油在热壁面上的着火

栗元龙,陆守香,范维澄

《中国工程科学》 2004年 第6卷 第11期   页码 63-65

摘要:

研究了柴油机燃料泄漏后在热壁上的着火,利用统计方法得到着火的临界温度。发现样品燃料的热壁着火温度与自燃点的差值比其它燃料热壁着火的相应值要小得多,而且着火方式也有很大差异。详细解释了泄漏后的液体在热表面上的沸腾蒸发模式,给出了燃料蒸气的质量流率推导公式。

关键词: 热壁面     着火实验     沸腾    

油缸实时检测系统控制策略研究

龚进,谭青,赵喻明,衡保利

《中国工程科学》 2011年 第13卷 第3期   页码 71-76

摘要:

针对现有油缸检测系统检测手段和技术落后及检测精度低等缺点,提出把测试项目模块化后,将模块有机组织在液压缸运行过程中来完成油缸检测的控制策略。运用PLC(programmable logic controller,可编程控制器)控制、CoDeSys组态软件和Visual Basic 6.0技术设计了一套油缸实时检测系统。试验结果表明,新的测试系统实现了实时检测、试验数据和曲线以及试验报告的输出和打印,提高了检测效率。

关键词: 油缸     实时检测     模块化     控制策略    

Impact of oxygen enriched combustion on the performance of a single cylinder diesel engine

K. RAJKUMAR, P. GOVINDARAJAN

《能源前沿(英文)》 2011年 第5卷 第4期   页码 398-403 doi: 10.1007/s11708-011-0157-7

摘要: In the present experiment, a computerized single cylinder diesel engine with a data acquisition system was used to study the effects of oxygen enriched combustion technology (OECT) on the performance characteristics. The use of different levels of oxygen-enriched air was compared with respect to percentage load. Increasing the oxygen content in the air leads to faster burn rates and increases the combustibility at the same stoichiometry (oxygen-to-fuel ratio). These effects have the potential to increase the thermal efficiency and specific power output of a diesel engine. The power increases considerably with oxygen enrichment. In addition, oxygen enrichment can also be considered as a way to reduce the sudden loss in power output when the engine operates in a high load condition. Assessed high combustion temperature from the oxygen enriched combustion leads to high combustion efficiency. OECT reduces the volume of flue gases and reduces the effects of greenhouse effects. Engine tests were conducted in the above said engine for different loads and the following performance characteristics like brake power (BP), specific fuel consumption (SFC), mean effective pressure, brake thermal efficiency, mechanical efficiency, and exhaust gas temperature were studied. The objective of this paper is to address, in a systematic way, the key technical issues associated with applying OECT to single cylinder diesel engines.

关键词: oxygen enriched combustion     exhaust gas temperature     brake power (BP)     specific fuel consumption (SFC)    

标题 作者 时间 类型 操作

Numerical study on natural convection in a square enclosure containing a rectangular heated cylinder

Jianhua LU, Zhaoli GUO, Zhenhua CHAI, Baochang SHI,

期刊论文

A pneumatic cylinder driving polyhedron mobile mechanism

Wan DING, Sung-Chan KIM, Yan-An YAO

期刊论文

Thermodynamic models and energy distribution of single-phase heated surface in a boiler under unsteady

Xiyan GUO, Yongping YANG

期刊论文

A numerical study of helium-heated inorganic membrane reformer coupling to HTGR

YIN Huaqiang, JIANG Shengyao, JU Huaiming, ZHANG Youjie

期刊论文

Enhancing fatigue life of cylinder-crown integrated structure by optimizing dimension

Weiwei ZHANG,Xiaosong WANG,Zhongren WANG,Shijian YUAN

期刊论文

Antifungal and antibacterial functions of medicinal leech recombinant destabilase-lysozyme and its heated-up

T. G. YUDINA, Danyang GUO, N. F. PISKUNKOVA, I. B. PAVLOVA, L. L. ZAVALOVA, I. P. BASKOVA

期刊论文

Convective mass transfer from a horizontal rotating cylinder in a slot air jet flow

Hongting MA , Dandan MA , Na YANG ,

期刊论文

Unified solution of limit loads of thick wall cylinder subject to external pressure considering strain

CHEN Changfu, XIAO Shujun, YANG Yu

期刊论文

Refined analysis of axi-symmetric circular cylinder in the axial magnetic field without ad hoc assumption

Baosheng ZHAO, Yang GAO, Yingtao ZHAO, Dechen ZHANG

期刊论文

Hydraulic fracturing pressure of concentric double-layered cylinder in cohesive soil

期刊论文

Effect of heat transfer space non-uniformity of combustion chamber components on in-cylinder heat transfer

Jizu LV, Minli BAI, Long ZHOU, Jian ZHOU,

期刊论文

Combustion and emissions of RP-3 jet fuel and diesel fuel in a single-cylinder diesel engine

期刊论文

柴油在热壁面上的着火

栗元龙,陆守香,范维澄

期刊论文

油缸实时检测系统控制策略研究

龚进,谭青,赵喻明,衡保利

期刊论文

Impact of oxygen enriched combustion on the performance of a single cylinder diesel engine

K. RAJKUMAR, P. GOVINDARAJAN

期刊论文