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External Characteristics and Internal Flow Features of a Centrifugal Pump during Rapid startup

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Chinese Journal of Mechanical Engineering 2011年第5期24卷 798-804页

作者： ZHU Zuchao GUO Xiaomei CUI Baoling LI Yi Laboratory of Fluid Power Transmission Zhejiang Sci-Tech University Hangzhou 310018 China Mechanical and Electronic Engineering Department Zhejiang Water Conservancy and Hydropower College Hangzhou 310018 China

Centrifugal pumps always work under steady conditions,and many researches focus on the steady *** transient conditions,such as sudden startup and shutdown,are *** researches on the inner flow of centrifugal pumps under transient conditions have been done,and they show that the transient operation is different from the steady *** order to research the evolution of unsteady flow in a centrifugal pump under transient conditions,and to investigate the mechanism of transient effects by analyzing the unsteady flow in a centrifugal pump,the external characteristic experiment and the internal flow numerical calculation of the centrifugal pump with an open impeller during startup is *** relationships of the rotation speed,capacity and head between start-time are obtained by the external characteristics *** numerical calculations under startup process are carried out by using the k-e model and N-S *** distribution of velocity and pressure in the inner channel of the tested pump was obtained by choosing fourteen start-time points and twelve geometrical points in the impeller channel during *** calculation results show that the velocity and the pressure increase linearly with the start-time before rotation＇s speed gets steady,then changes almost horizontally after rotation speed becomes steady,then fluctuates until being *** internal flow characteristics are in good agreement with the external characteristic experimental results and numerical *** simulation methods and results make the basis for the diagnosis and optimization of under flow in the centrifugal pump during transient operation.

关键词： centrifugal pump numerical calculation transient condition startup

Experimental Study on a Centrifugal Pump with an Open Impeller during startup Period

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Journal of Thermal Science 2013年第1期22卷 1-6页

作者： Yuliang Zhang Zuchao Zhu Yingzi Jin Baoling Cui Yi Li Huashu Dou The State Key Lab of Fluid Power Transmission and Control Zhejiang University The Province Key Lab of Fluid Transmission Technology Zhejiang Sci-Tech University

Transient performance of fluid machinery during transient operating periods, such as startup and stopping, has been drawn more attentions recently due to the growing engineering needs. In this paper, the transient behavior of a prototype centrifugal pump with an open impeller during rapid startup period is studied experimentally. The variations of the rotational speed, flow rate, head, and shaft power during rapid startup period are recorded in ex- periments at different discharge valve openings. In addition, the non-dimensional flow rate and head are also used to analyze the transient behavior. The research result shows that the rise characteristic of the rotational speed is not basically changed by working points, while mainly depends on the startnp characteristics of the driving motor. Compared with the rapid rise of the rotational speed, the flow rate rises slowly in the initial stage of startup. Moreover, the flow rate lags behind the rotational speed to rise to final stable value, and the delay becomes more severe with the increase of the discharge valve opening. The shaft power impact phenomenon generally exists in the process of startup. The non-dimensional analysis shows that the non-dimensional head is very high at the very beginning of startup, and quickly falls to the minimum, then gradually rises to final stable value, while the non-dimensional flow rate always shows the rise tendency during whole startup period. In conclusion, it is found from the non-dimensional results that the quasi-steady analysis is unable to accurately assess the transient flow during startup period.

关键词： centrifugal pump open impeller startup experimental study transient behavior

Computational Analysis of Centrifugal Pump Delivering Solid-liquid Two-phase Flow during startup Period

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Chinese Journal of Mechanical Engineering 2014年第1期27卷 178-185页

作者： ZHANG Yuliang LI Yi ZHU Zuchao CUI Baoling The State Key Lab of Fluid Power Transmission and Control Zhejiang University College of Mechanical Engineering Quzhou University The Province Key Lab of Fluid Transmission Technology Zhejiang Sci-Tech University

The transient behavior of centrifugal pumps during transient operating periods, such as startup and stopping, has drawn more and more attention recently because of urgent needs in engineering. Up to now, almost all the existing studies on this behavior are limited to using water as working fluid. The study on the transient behavior related to solid-liquid two-phase flow has not been seen yet. In order to explore the transient characteristics of a high specific-speed centrifugal pump during startup period delivering the pure water and solid-liquid two-phase flow, the transient flows inside the pump are numerically simulated using the dynamic mesh method. The variable rotational speed and flow rate with time obtained from experiment are best fitted as the function of time, and are written into computational fluid dynamics （CFD） code-FLUENT by using a user defined function. The predicted heads are compared with experimental results when pumping pure water. The results show that the difference in the transient performance during startup period is very obvious between water and solid-liquid two-phase flow during the later stage of startup process. Moreover, the time for the solid-liquid two-phase flow to achieve a stable condition is longer than that for water. The solid-liquid two-phase flow results in a higher impeller shaft power, a larger dynamic reaction force, a more violent fluctuation in pressure and a reduced stable pressure rise comparing with water. The research may be useful to tmderstanding on the transient behavior of a centrifugal pump under a solid-liquid two-phase flow during startup period.

关键词： centrifugal pump solid-liquid two-phase flow startup transient performance

Numerical investigation on the startup performance of high-temperature heat pipes for heat pipe cooled reactor application

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Nuclear Science and Techniques 2021年第10期32卷 143-155页

作者： Yu-Chuan Guo Zi-Lin Su Ze-Guang Li Kan Wang Department of Engineering Physics Tsinghua UniversityBeijing 100084China

A suitable model for high-temperature heat pipe startup is a prerequisite to realizing the numerical simula-tion for the heat pipe cooled reactor startup from the cold *** is required that this model not only describes the transient behavior during the startup period,but also reduces the computing resources of the heat pipe cooled reactor simulation in the simplest *** this study,a simplified model that integrates the two-zone and network models is *** this model,vapor flow in the vapor space,evaporation,and condensation in the vapor–liquid interface are decoupled with heat conduction to achieve a fast calculation of the transient characteristics of the heat *** experimental system for a high-temperature heat pipe was developed to validate the proposed model.A potassium heat pipe was utilized as the experimental *** experiments were performed with differ-ent heating *** with the experimental results,the accuracy of the proposed model was ***,the proposed model can predict the vapor flow,pressure drop,and temperature drop in the vapor *** indicated by the analysis results,the essential requirements for successful startup are also *** heat pipe cannot achieve a successful startup until the heating power satisfies these *** the discussions indicate the capability of the proposed model for the simulation of a high-temperature heat pipe startup from the frozen state;hence,can act as a basic tool for the heat pipe cooled reactor simulation.

关键词： High-temperature heat pipe startup Two-zone model Network model

startup Speed with Dead Band in Wind Farms with Low-Medium Wind Speed Profile—Case Study of Hong Kong

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Energy and Power Engineering 2017年第4期9卷 562-572页

作者： Zuliang Yin Bo Bai Jiani Liu Sheng Su College of Electrical and Electronic Engineering Changsha University of Science and Technology Changsha China

Wind turbines are usually designed and operated with fixed startup speed. It could perform startup and shutdown operations repeatedly when the wind fluctuates around the startup speed. The excessive stress induced by frequent startup and shutdown could enhance the likelihood of component failure and hence negatively impact the availability of a wind turbine. startup speed with dead band is proposed in this article to prevent the wind turbine from frequent startup. 22 years wind data from the Cheung Chau wind station in Hong Kong are analyzed to evaluate the reduction in the number of startup and potential loss of wind power production using the proposed approach. Numerical simulation suggests that the number of startup could be reduced by half with trivial reduction in potential wind power generation in most of investigated sites once an appropriate dead band is adopted.

关键词： Wind Power Wind Turbine startup Dead Band

Study and Application of W-Flame Boiler startup Aided by Adjacent Hot Primary Air

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Electricity 2012年第3期23卷 34-38页

作者： Hou Zhaoyi Qiu Xiantang Du Huazhong Guodian Heze Power Plant

In this paper,the designed features of a W-flame coal-fired boiler are introduced.A scheme of joint primary air for two boilers is made and technical measures are also taken based on corresponding analyses and *** scheme and the measures provide a reference for technicians to improve the efficiencies and reduce the startup costs of other similar large boilers.

关键词： W-flame coal-fired boiler joint hot primary air startup energy-saving

Effects of Beam startup Characteristics on Dose Delivery Accuracy at Low Monitor Units in Step-and-Shoot Intensity Modulated Radiation Therapy

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International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2013年第1期2卷 1-5页

作者： Kazunori Fujimoto Kunihiko Tateoka Yuji Yaegashi Katsumi Shima Junji Suzuki Yuichi Saito Akihiro Nakata Takuya Nakazawa Tadanori Abe Masaki Yano Masanori Someya Kensei Nakata Masakazu Hori Masato Hareyama Koichi Sakata Department of Medical Physics Graduate School of Medicine Sapporo Medical University Sapporo Japan Department of Radiology Sapporo Medical University Sapporo Japan Radiation Therapy Research Institute Social Medical Corporation Teishinkai Sapporo Japan

Intensity modulated radiation therapy (IMRT) is a highly accurate technique that is usually implemented in either dynamic or step-and-shoot fashion with many segments each having low monitor units (MUs). The present study evaluated the effects of beam startup characteristics on the dose delivery accuracy for each segment at low MUs for step-and-shoot IMRT with an Elekta Precise accelerator at the highest dose rates. We used a two-dimensional semi-conductor detector for the dose measurements. The field size of each segment was assumed to be 20 ×20 cm2 and each segment was set to deliver 1 - 10 MUs. Our results show a variation in dose delivery accuracy between segments for the same IMRT beam, which can be attributed to the beam startup characteristics. This variability is attributed to the changes in the transient changes in the temperatures of the electron gun filament and the magnetron. That is, the transient increase in the temperature of the filament leads to increasing doses with time and that of the magnetron leads to decreasing doses with time during the first few MUs.

关键词： startup Performance Step-and-Shoot IMRT Low Monitor Units

SLINGSHOT 2019 startup Competition

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China Standardization 2019年第3期84卷 58-58页

Asia's most exciting deep tech startup competition is back!Now in its 3rd edition,SLINGSHOT 2019 gives promising startups a global platform to showcase their tech and business ideas in front of the most important inve... 详细信息

关键词： Asia SLINGSHOT startup Competition

加拿大Domtar公司新的绒毛浆生产线投产New Fluff Pulp Machine startup

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生活用纸 2011年第5期11卷 14-14页

作者：陈祥津(译) 章杰(审校)

据位于加拿大魁北克省蒙特利尔市的Domtar公司消息，该公司在美国北卡罗来纳州Plymouth厂的新的绒毛浆设备已经按计划如期于2011年初开工运行。该厂的绒毛浆生产能力将达到44．4万t／a左右。

关键词： ar公司 startup 绒毛浆加拿大生产线投产北卡罗来纳州蒙特利尔市