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DENSITY WAVE INSTABILITY IN ONCE-THROUGH BOILING FLOW SYSTEM, .3. distributed parameter model

JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY 1979年第1期16卷 16-29页

作者： TAKITANI, K SAKANO, K KAWASAKI HEAVY IND LTD DEPT NUCL POWER ENGN MINATO KU TOKYO 105 JAPAN

The density wave instability in a once-through boiling flow system is analyzed using a comprehensive distributed parameter model that is extended from the simplified lumped parameter model presented in a companion paper. A computer code DEW is developed for the calculations with an analytical approach in the time domain. The proposed model is verified by comparison with published data obtained from experiments with a joule-heated system and a sodium-heated steam generator. This comparison indicates that the proposed model can serve as a design tool for predicting the stability boundary. Several features of oscillatory behavior, the existence of higher-mode oscillations and some analytical parameter effects on the flow instability are revealed in the present study.

关键词： analytical study density wave instability once-through boiling flow system distributed parameter model time domain computer codes experimental verification joule-heated data sodium-heated data stability accuracy comparative evaluations

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The distributed parameter model of hydraulic axial piston motor and its application in hydraulic excavator swing system

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART I-JOURNAL OF SYSTEMS AND CONTROL ENGINEERING 2017年第5期231卷 395-413页

作者： Gao, Youshan Huang, Weinan Quan, Long Lan, Yuan Huang, Jiahai Taiyuan Univ Technol Sch Mech Engn Key Lab Adv Transducers & Intelligent Control Sys Minist Educ Taiyuan 030024 Peoples R China Taiyuan Univ Sci & Technol Sch Mech Engn Taiyuan Peoples R China

Hydraulic axial piston motor is one of the fundamental components in hydraulic systems;it is widely used in engineered machine, especially in high-power drive or reciprocating motion, such as hydraulic excavator. For hydraulic axial piston motor efficient planning, in addition designing and controlling are required for system operating safety and efficiency. Simulation delivers an advantage over analytical approaches and allows better understanding of the motor performance. For multi-piston hydraulic motor, one of the simulation methods, distributed parameter model, could analyze the detailed performance in each piston chamber. Therefore, in this study, we investigate the characteristics of hydraulic axial piston motor by setting up a distributed parameter model based on physical prototype, which includes mechanical-hydraulics coupling process. The effects of the dynamic pressure inside the piston chamber, the fluidic compressibility and other related parameters are considered in the coupling process. At the same time, the distributed parameter model of hydraulic axial piston motor was used in the simulation model of hydraulic excavator. The results indicate that in two-way hydraulic axial piston motor, the valve plane should adopt symmetrical structure, and silencing groove set should be put on both ends of the valve plane slots, which could reduce pressure ripple and overshoot in the piston chamber. Furthermore, the torque characteristics are highly affected by the clearance between the piston and the cylinder bore. Through this research, we may have a better understanding about the mechanism of output torque fluctuation in hydraulic axial piston motor, and the pressure ripple and overshoot in the piston chamber due to through-flow area discontinuity between the silencing groove and the ends of the valve plane slots. The model is verified using a nine-piston hydraulic motor in hydraulic excavator.

关键词： Hydraulic axial piston motor distributed parameter model mechanical-hydraulics coupling simulation pressure pulsation leakage flow

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Confidence Analysis Method for Cable distributed parameter model based on Verification & Validation

Confidence Analysis Method for Cable Distributed Parameter M...

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IEEE-MTT-S International Conference on Numerical Electromagnetic and Multiphysics modeling and Optimization (NEMO)

作者： Liu, Qiang Zhong, Longquan Yan, Liping Zhao, Xiang Zhou, Haijing Inst Appl Phys & Computat Math Beijing Peoples R China China Acad Engn Phys Inst Appl Elect Mianyang Sichuan Peoples R China Sichuan Univ Coll Elect & Informat Engn Chengdu Peoples R China

ISBN: (纸本)9781728169668

An effective confidence analysis method for the cable distributed parameter model is proposed in this paper, while it is still a blank question at present. As the cable electromagnetic coupling model is composed of a transmission line model and a distributed parameter model, the proposed confidence analysis method takes two steps based on verification & validation (V&V) theory. One step is that confidence analysis of both models is completed by getting numerical calculation accuracy verified with numerical results and model accuracy validated with experiments results, to confirm the quantification of numerical calculation errors and model accuracy errors analysis. The other step is that the confidence analysis of the cable distributed parameter model must be established on the basis of that of the transmission line model. Such method is completed and confirmed with numerical and experimental examples in this paper. Further more, confirmed confidence of cable model leads to the validity of simulation data, which is an important mathematical foundation for simulation to produce practical results in cable layout engineering design and electromagnetic response evaluation.

关键词： cable electromagnetic coupling distributed parameter model transmission line model verification & validation

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Force Control of Dual-Manipulator Handling a Flexible Payload Based on distributed parameter model

Force Control of Dual-Manipulator Handling a Flexible Payloa...

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Chinese Automation Congress (CAC)

作者： Liu, Shuyang Li, Yuanchun Langari, Reza Changchun Univ Technol Dept Control Engn Changchun Jilin Peoples R China Texas A&M Univ Dept Mech Engn College Stn TX 77843 USA

ISBN: (纸本)9781728113128

This paper presents an exact dynamic model of a dual-manipulator handling a flexible payload by using Hamilton's principle. On the basis of the distributed parameter model, a force controller is designed via Lyapunov theory. The controller can accomplish the desired contact force between the manipulator and the flexible payload while achieving the given desired link angles, and simultaneously suppressing the vibration of the flexible payload. All the states used in the controller are readily available so that the proposed method is feasible to implement.

关键词： force control distributed parameter model flexible payload Lyapunov function

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A distributed parameter model of frame pin-supported wall structure

A distributed parameter model of frame pin-supported wall st...

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IABSE Conference, Nara 2015: Elegance in Structures

作者： Wu, Shoujun Pan, Pang Tsinghua University Beijing China

ISBN: (纸本)9783857481383

Rocking structure is a kind of novel structure system, which release constraints in some part of a structure. Frame pin-supported wall structure is a kind of rocking structure, in which walls are hinged at the bottom. Most of previous research concerning frame pin-supported wall structure focused on the overall behaviour, while the inner force and strength demand of the wall is not well discussed. In this paper, a distributed parameter model of frame pin-supported wall structure is developed. The wall and frame are simplified as a bending beam and a shear beam, respectively. The accuracy of the model is verified by SAP2000, for two typical external force profiles, i.e. uniform and invert triangular. It is found that the distributed parameter model gives a fairly accurate estimation of displacement, moment and shear of frame pin-supported wall structure. Distribution of displacement and inner force of pin-supported wall can be given with the model.

关键词： distributed parameter model Frame pin-supported wall structure Stiffness demand Strength demand

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Unsynchronized fault location on untransposed transmission lines with fully distributed parameter model considering line parameter uncertainties

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ELECTRIC POWER SYSTEMS RESEARCH 2022年第0期202卷 107622-107622页

作者： Lu, Dian Liu, Yu Lu, Dayou Wang, Binglin Zheng, Xiaodong ShanghaiTech Univ Sch Informat Sci & Technol 393 Middle Huaxia Rd Shanghai 201210 Peoples R China Chinese Acad Sci Shanghai Adv Res Inst Shanghai Peoples R China Chinese Acad Sci Shanghai Inst Microsyst & Informat Technol Shanghai Peoples R China Univ Chinese Acad Sci Beijing Peoples R China Shanghai Jiao Tong Univ Minist Educ Key Lab Control Power Transmiss & Convers Shanghai Peoples R China

This paper proposes an unsynchronized two-terminal fault location method on three phase untransposed transmission lines considering line parameter uncertainties. The method utilizes three phase voltage and current phasor measurements before and during the fault, without requirement of synchronization between two terminals. The proposed method first formulates the fault location problem considering line parameter uncertainties in a standard syntax, where the distributed parameters as well as the asymmetry of untransposed transmission lines are carefully considered to ensure accurate representation of physical laws before and during the fault. The location of the fault and unknown parameters of the untransposed transmission line are introduced as states of the system. Afterwards, the states of the system, including the location of the fault, are systematically solved using the state estimation algorithm. Extensive numerical experiments validate that the proposed method has higher accuracy compared to the existing fault location methods considering line parameter uncertainties, regardless of fault types, locations and impedances.

关键词： Fault location Line parameter uncertainties Asymmetry distributed parameter model Transmission line Unsynchronization

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A distributed parameter model of refrigerant-cooled multi-channel evaporator for battery thermal management

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ENERGY 2024年 304卷

作者： Lu, Jingchao Zhuang, Dawei Ding, Guoliang Li, Guang Wang, Yueming Shanghai Jiao Tong Univ Sch Mech Engn Shanghai 200240 Peoples R China

Application of refrigerant-cooled multi-channel evaporators (MCEs) is a promising solution to cool electric vehicle batteries because the non-uniformly distributed heat from a battery can be efficiently dissipated by suitable arrangement of the multi-channels in an MCE. In order to provide a simulation tool for the design of an MCE, a distributed parameter model for quickly predicting the performance of an MCE at various channel arrangements and non-uniformly distributed heating conditions is useful, and thus it is developed in this study. In the model, heat and mass transfer in multiple flow paths in an MCE are separately described;the uneven mass flow distribution among these channels is predicted based on the pressure balance;each flow path is divided into multiple control volumes to reflect the non-uniformly distributed heating conditions;and the mass flow distribution among flow paths and the heat transfer in all the control volumes are jointly solved by a combined iteration algorithm of pressure drop and heat transfer. The proposed model is validated by experiments under the condition of battery heat flux ranging from 500 to 1500 W m(-2). The results show that the prediction deviations of the average temperature and the highest temperature on the MCE surface from the experimental ones are 1.5 degrees C and 1.6 degrees C, respectively, which indicates that the proposed model can well predict the thermal performance of MCE under non-uniformly distributed battery heat.

关键词： Refrigerant-cooled multi-channel evaporator distributed parameter model Battery thermal management Non-uniform heat flux

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Unsteady-state heat transfer characteristics of spiral water wall tube in advanced-ultra-supercritical boilers from experiments and distributed parameter model

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ENERGY 2019年 189卷

作者： Ge, Xueli Zhang, Zhongxiao Fan, Haojie Zhang, Jian Bi, Degui Shanghai Jiao Tong Univ Sch Mech Engn 800 Dongchuan Rd Shanghai 200240 Peoples R China

The design and operation of water walls are crucial for ultra-supercritical boilers, particularly with the advent of advanced-ultra-supercritical (A-USC) boilers. In this study, heat transfer characteristics for a spiral water wall were analysed in a 0.3 MWt experimental facility to understand the combustion and hydrodynamics of A-USC boilers. The working pressure ranged from 13.5 to 41.0 MPa, while mass flux varied from 124.4 to 557.1 kg/(m(2).s), along with a maximum heat flux of approximately 448 kW/m(2). As the heat flux was increased, evidently enhanced and deteriorated heat transfer performances were observed near the pseudo-critical point during the unsteady operating process. The distributed parameter model was employed along with different correlations from literatures to predict the distribution of temperatures and heat transfer coefficients. Predicted temperatures were compared with the experimental measurements. The results demonstrated that distributed parameter model combining with appropriate correlation for each region, yielded good agreement with the experimental data. Particularly, for the top, middle, and bottom regions of the furnace, the correlations by Swenson et al., Jackson et al., and Mokry et al., respectively are found to be suitable. Furthermore, a criterion for heat transfer deterioration for the spiral water wall was also suggested for the A-USC units. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Unsteady-state heat transfer Advanced ultra-supercritical boiler Experimental investigation distributed parameter model Spiral water wall

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A distributed parameter model for multi-row separated heat pipe with micro-channel heat exchangers

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APPLIED THERMAL ENGINEERING 2021年 182卷 116113-116113页

作者： Xia, Guanghui Zhuang, Dawei Ding, Guoliang Lu, Jingchao Han, Weizhe Qi, Hanyun Shanghai Jiao Tong Univ Sch Mech Engn Shanghai 200240 Peoples R China Weyee Heat Exchanger Corp Ltd Danyang 212311 Peoples R China

Multi-row separated heat pipes (SHPs) with micro-channel heat exchangers are widely used to cool electronic equipment as they have the advantage of cooling capacity adjustment by changing the row quantity of heat exchanger. The non-uniform distributed refrigerant flow and the interaction of air among rows may have significant effects on the performance of multi-row SHPs, and a distributed parameter model reflecting these characteristics is proposed in this study. In this model, all components, i.e. evaporator, ascending tube, condenser and descending tube, are mathematically described individually;the refrigerant flow is described as uneven flow among tubes and the flow direction is fixed in each tube;the air flow is modelled as the flow with two-dimensional distribution at windward and with fixed direction across all rows. The proposed model is validated by experiments, and the results show that, the relative deviation of heat transfer capacity is 3.5%, and the absolute deviations of temperature difference and outlet air temperatures of evaporator and condenser are 0.3 degrees C, 2.3 degrees C and 0.9 degrees C, respectively. The cooling capacity distribution in various rows of multi-row SHP is presented based on simulation, which is beneficial for determination of suitable row quantity of heat exchanger.

关键词： Separated heat pipe Multi-row distributed parameter model Micro-channel Graph theory Electronic cooling

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A novel noniterative single-ended fault location method with distributed parameter model for AC transmission lines

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INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS 2023年第1期153卷

作者： Duan, Mengzhao Liu, Yu Lu, Dian Pan, Ruiyu ShanghaiTech Univ Sch Informat Sci & Technol Shanghai 201210 Peoples R China Minist Educ Key Lab Control Power Transmiss & Convers SJTU Shanghai 200240 Peoples R China

Fast and accurate fault location methods can save costs and ensure power supply reliability. This paper proposes a novel noniterative single-ended phasor domain fault location method with distributed parameter model for AC transmission lines. Due to the limitation of information, the legacy impedance-based single-ended fault location methods usually are based on assumptions on the line or system to obtain more information. The method proposed in this paper takes advantage of the additional information brought by the operation mode of circuit breakers. The proposed method only needs the local measurements and does not need the measurements and the equivalent source parameters of the remote system. The proposed method only uses single-ended data and is not affected by communication and synchronization. The proposed method is noniterative and there is no risk of nonconvergence. In addition, the method proposed in this paper does not rely on the assumptions of legacy methods and considers the distributed parameters, avoiding the disadvantages of the legacy methods. The effectiveness of the proposed method is verified through a lot of case studies in PSCAD/EMTDC, with different fault types, fault locations and resistances. & COPY;2017 Elsevier Inc. All rights reserved.

关键词： Fault location Noniterative method Single-ended measurements distributed parameter model

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