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Influence of Cavitation on Unsteady Vortical Flows in a Side Channel Pump

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Chinese Journal of Mechanical Engineering 2023年第1期36卷 171-189页

作者： Yefang Wang Fan Zhang shouqi yuan Ke Chen Feng Hong Desmond Appiah National Research Center of Pumps Jiangsu UniversityZhenjiang212013China College of Mechanical&Power Engineering China Three Gorges UniversityYichang443002China

Previous investigation on side channel pump mainly concentrates on parameter optimization and internal unsteady vortical flows.However,cavitation is prone to occur in a side channel pump,which is a challenging issue in promoting performance.In the present study,the cavitating flow is investigated numerically by the turbulence model of SAS combined with the Zwart cavitation model.The vapors inside the side channel pump firstly occur in the impeller passage near the inlet and then spread gradually to the downstream passages with the decrease of NPSHa.Moreover,a strong adverse pressure gradient is presented at the end of the cavity closure region,which leads to cavity shedding from the wall.The small scaled vortices in each passage reduce significantly and gather into larger vortices due to the cavitation.Comparing the three terms of vorticity transport equation with the vapor volume fraction and vorticity distributions,it is found that the stretching term is dominant and responsible for the vorticity production and evolution in cavitating flows.In addition,the magnitudes of the stretching term decrease once the cavitation occurs,while the values of dilatation are high in the cavity region and increase with the decreasing NPSHa.Even though the magnitude of the baroclinic torque term is smaller than vortex stretching and dilatation terms,it is important for the vorticity production along the cavity surface and near the cavity closure region.The pressure fluctuations in the impeller and side channel tend to be stronger due to the cavitation.The primary frequency of monitor points in the impeller is 24.94 Hz and in the side channel is 598.05 Hz.They are quite corresponding to the shaft frequency of 25 Hz(fshaft=1/n=25 Hz)and the blade frequency of 600 Hz(fblade=Z/n=600 Hz)respectively.This study complements the investigation on cavitation in the side channel pump,which could provide the theoretical foundation for further optimization of performance.

关键词： Side channel pump Vortical flows Cavitation Vortex-cavitation interaction Pressure fluctuation

Synergistic Modification of PVC with Nitrogen-Containing Heterocycle and Tung-Oil Based Derivative for Enhanced Heat Stabilization and Plasticization Behavior

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Journal of Renewable Materials 2023年第4期11卷 2015-2031页

作者： Mei Wang Xinzhu Fan Quan Bu Puyou Jia shouqi yuan School of Agricultural Engineering Jiangsu UniversityZhenjiang212013China Institute of Chemical Industry of Forest Products Chinese Academy of Forestry(CAF)Nanjing210042China Key Laboratory of Chemistry and Engineering of Forest Products State Ethnic Affairs CommissionGuangxi Key Laboratory of Chemistry and Engineering of Forest ProductsGuangxi University for NationalitiesNanning530006China Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang212013China

The additives present in polyvinyl chloride(PVC)materials are the major source of organic by-products during PVC degradation.The thermal stabilizer and plasticizer are the main additives that endow PVC with the required properties during its processing.However,these two additives easily migrate when samples are obtained by physical mixing of the additives with PVC.This causes the reduction of PVC sample efficacy and the increase in the formation of organic by-products in the radiolysis process.In this work,two kinds of grafted PVC samples(tungoil derivative grafted PVC and Atz grafted PVC,abbreviated as P-GT4 and P-AZ3)were synthesized by chemical grafting of 3-amino-1,2,4-triazole(Atz)and tung-oil derivative on PVC,respectively.These two PVC samples were then blended at different mass ratios to obtain hybrid PVC materials with excellent plasticization,thermal stability and migration resistance ability.Differential scanning calorimetry(DSC),discoloration,Congo red test and thermogravimetric analysis(TGA)showed that when the mass ratio of P-GT4 to P-AZ3 in the mixed PVC resin was 1:3,the resulting P1:3-GT4-AZ3(P4)presented the best plasticization and thermal stability.The kinetics of thermal decomposition showed that the activation energy of P4 was much higher than that of the reference material[PVC/DOTP/CaSt2/ZnSt2,PVC/CZ41 for short]at mass lossα=20%and 80%.In addition,the leaching test showed that P4 material possessed excellent migration resistance ability.

关键词： Polyvinyl chloride synergistic self-stabilization internal plasticization 3-amino-1,2,4-triazole tung-oil derivative

应急供水多级泵意外停机水力过渡过程瞬态特性

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农业工程学报 2024年第4期40卷 72-81页

作者：司乔瑞夏欣武凯鹏邓凡杰袁寿其江苏大学流体机械工程技术研究中心镇江212013

应急供水多级泵的意外停机会引起系统性能参数的剧烈变化,严重威胁供水安全。为了探究多级泵停机水力过渡过程内部流场的瞬态效应,该研究建立了基于叶轮转动平衡方程的泵停机过程转速预测方法,数值模拟分析了意外停机过程中多级泵内部... 详细信息

应急供水多级泵的意外停机会引起系统性能参数的剧烈变化,严重威胁供水安全。为了探究多级泵停机水力过渡过程内部流场的瞬态效应,该研究建立了基于叶轮转动平衡方程的泵停机过程转速预测方法,数值模拟分析了意外停机过程中多级泵内部流动特性。研究结果表明:在意外停机过程中,多级泵分别经历水泵工况、制动工况、反转工况以及飞逸工况4个阶段,转速呈现先减小至0后沿负方向增大的趋势,最后稳定在飞逸转速-4210 r/min附近;流量呈现先减小至0后沿负方向增大的趋势,然后再沿正方向增大,最终稳定在飞逸流量-14.32 kg/s附近;扭矩呈现先减小再增加,最后减小并稳定在零点附近。泵内流量和转速的大小、方向不断变化引起叶轮流道内流体的流动分离和回流,伴随着涡的形成、发展和破碎等时空演变;熵产值的变化与多级泵内不稳定流动密切相关,由湍流耗散所带来的损失起主导作用,在达到飞逸工况后湍流耗散熵产占比约65.2%,能量损失主要发生在叶轮流道内,且制动工况中内流场的损失较大;多级泵首级流道内监测点压力变化最为剧烈,各级监测点的压力脉动系数波动幅值随着级数的增加呈减小趋势;压力脉动振幅主导频率与多级泵转速呈现正相关关系,主导分量对应于叶轮流道的叶片通过频率,且沿着流体流动方向压力脉动频率振幅逐渐增大,压力脉动的频率特性可以反应出意外停机过程中流量的不稳定变化。研究成果可为应急供水系统安全稳定运行提供理论指导。

关键词：离心泵瞬态效应内部流动意外停机熵产分析

Performance experiment and numerical prediction on the optimization design of the micro-sized water turbine for the hose reel irrigator

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International Journal of Agricultural and Biological Engineering 2018年第5期11卷 108-115页

作者： Lingdi Tang shouqi yuan Yue Tang Haofang Yan Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenJiang 212013China

In order to significantly improve the efficiency of driving water turbine used in hose reel irrigator,a new water turbine structure was proposed by the method of performance test and numerical calculation.The internal flow characteristics of original water turbine were analyzed,and it was found that unreasonable design of main flow passage components such as inlet,outlet and runner could not effectively translated pressure energy of upper stream into impact kinetic energy of blade,and gave rise to low energy conversion efficiency of water turbine.The inadequate internal flow and uneven pressure distribution were also not conducive to energy conversion efficiency.Then a new structure of water turbine structure was presented,in which the inlet has a tangential nozzle jet and the outlet is in axial direction.The computational analysis showed that the nozzle jet at the inlet of the new water turbine runner,which makes jet flow mainly concentrate in the impacted blade passage,can reduce the loss of flow kinetic energy.The axial outflow increases the distance of inflow in the runner,which is more conducive to the runner blades work.Performance experiments on both original and new water turbines showed that the highest efficiency of the new turbine is almost 20 percentages higher than that of the original turbine,and the new turbine is nearly triple output power over the original turbine.The internal flow characteristic analysis and the performance experiment were conducted to assess the feasibility of the replacement of the original water turbine by the new water turbine.

关键词： micro-sized water turbine hose reel irrigator optimization design experimental study numerical analysis

Investigation on the Flow Behavior of Side Channel Pumps Based on Vortex Identification

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Chinese Journal of Mechanical Engineering 2021年第6期34卷 298-315页

作者： Fan Zhang Desmond Appiah Ke Chen shouqi yuan Kofi Asamoah Adu-Poku Lufeng Zhu National Research Center of Pumps Jiangsu UniversityZhenjiang212013China Department of Physics Education University of EducationWinnebaGhana

The momentum flow exchange between the impeller and side channel produces highly turbulent flows in side channel pumps.The turbulent flows feature complex patterns of vortex structures that are partly responsible for the dissipation of energy losses and unsteady pressure pulsations.The concept of turbulent flows in side channel pumps requires a reliable vortex identification criterion to capture and predict the effects of the vortex structures on the performance.For this reason,the current study presents the application of the new Ω-criterion to a side channel pump model in comparison with other traditional methods such as Qand λ2 criteria.The 3D flow fields of the pump were obtained through unsteady Reynolds-averaged Navier-Stokes(RANS)simulations.Comparative studies showed that the Ω-criterion identifies the vortex of different intensities with a standard threshold,Ω=0.52.The Q and λ2 criteria required different thresholds to capture vortex of different intensities thus leads to subjective errors.Comparing theΩ-criterion intensity on different planes with the entropy losses and pressure pulsation,the longitudinal vortex plays an important role in the momentum exchange development which increases the head performance of the pump.However,the rate of exchange is impeded by the axial and radial vortices restricted in the impeller.Therefore,the impeller generates the highest entropy loss and pressure pulsation intensities which lower the output efficiency.Finally,the findings provide a fundamental background to the morphology of the vortex structures in the turbulent flows which can be dependent upon for efficiency improvement of side channel pumps.

关键词： Side channel pumps Ω-criterion Vortex Entropy loss

Comparison of droplet distributions from fluidic and impact sprinklers

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Frontiers of Agricultural Science and Engineering 2015年第1期2卷 53-59页

作者： Xingye ZHU shouqi yuan Junping LIU Xingfa LIU National Engineering Research Center of Pumps and Pumping System Jiangsu University Research Center of Fluid Machinery Engineering and Technology Jiangsu University

To adapt to the trend toward low-energy precision irrigation, the droplet distributions for two new prototype sprinklers, outside signal sprinkler(OS) and fluidic sprinkler(FS), were compared with impact sprinkler(IS). A laser precipitation monitor was used to measure the droplet distributions. Droplet size and velocity distributions were tested under four operating pressures for nozzles 1.5 m above the ground. For the operating pressures tested, the mean OS, FS and IS droplet diameters ranged from 0 to 3.4, 0 to 3.5, 0 to 4.0 mm, respectively.The mean OS and FS droplet velocities ranged from 0 to6.3 m$s–1, whereas IS ranged from 0 to 6.3 m$s–1. Being gas-liquid fluidic sprinklers, droplet distributions of the OS and FS were similar, although not identical. IS mostly produced a 0.5 mm larger droplet diameter and a 0.5 m$s–1greater velocity than OS and FS. A new empirical equation is proposed for determination of droplet size for OS and FS, which is sufficiently accurate and simple to use. Basic statistics for droplet size and velocity were performed on data obtained by the photographic methods. The mean droplet diameter(arithmetic, volumetric and median)decreased and the mean velocity increased in operating pressure for the three types of sprinkler.

关键词： outside signal sprinkler fluidic sprinkler impact sprinkler sprinkler irrigation droplet size droplet velocity

Development status and trend of agricultural robot technology

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International Journal of Agricultural and Biological Engineering 2021年第4期14卷 1-19页

作者： Yucheng Jin Jizhan Liu Zhujie Xu shouqi yuan Pingping Li Jizhang Wang Key Laboratory of Modern Agricultural Equipment and Technology Ministry of EducationJiangsu UniversityZhenjiang 212013JiangsuChina College of Biology and the Environment Nanjing Forestry UniversityNanjing 210042China

In the face of the contradiction between the increasing demand for agricultural products and the sharp reduction of agricultural resources and labor force,agricultural robot technology is developing explosively on the basis of decades of technical and industrial exploration.In view of the complexity and particularity of the development of agricultural robot technology,it is of great value to summarize its development characteristics and make reasonable judgments on its development trend.In this paper,the type of agricultural robot systems was first discussed.From the classification of agricultural robot systems,the development of main types of monitoring robots,non-selective and selective working robots for crop farming,livestock and poultry farming and aquaculture were introduced in detail.Then the scientific research,core technology,and commercialization of different types of agricultural robots were summarized.It is believed that navigation in complex agricultural environments,damage-free robot-crop interaction,and agronomy-robot fusion have high scientific value and significance to promote the revolutionary advances in agricultural robot technology.The characteristics of inter-discipline between agricultural robot technology and new materials,artificial intelligence,bionics,agronomy are research focus.The fast damage-free operation,autonomous navigation for complex environments,target detection for complex backgrounds,and special design for agricultural robots are considered to be the key technology of agricultural robot development,and the development path is given.Finally,robot-crop interaction simulation,big data support,and artificial intelligence are regarded as paths to realize the breakthrough of key agricultural robot technologies.The summary and prospect of this paper are of positive significance to promote the overall development of agricultural robot technology.

关键词： agricultural robot type selective non-selective trend

Irrigated agriculture for food self-sufficiency in the sub-Saharan African region

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International Journal of Agricultural and Biological Engineering 2020年第3期13卷 1-12页

作者： Ransford Opoku Darko Junping Liu shouqi yuan Livingstone K.Sam-Amoah Haofang Yan Research Centre of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang 212013China Department of Agricultural Engineering University of Cape CoastCentral RegionCape CoastPMB Ghana

Increasing agricultural productivity in Africa will have important impacts not only on the agricultural sector but also can be a catalyst for industrialization through agro-processing.Irrigation,therefore,has a crucial role in enhancing food security and reducing hunger in the region.Numerous countries in Africa consider water and irrigation management as a key factor in improving their food security and ensuring access to drinking-water for their populations.Fortunately,there is evidence from a number of places on the continent where the adoption of efficient irrigation systems has led to higher productivity among smallholder farmers.While the appropriate interventions for the diverse agro-ecological zones of sub-Saharan Africa are known,adoption among smallholder farmers still remains a challenge.Digital technology opens the vast untapped potential for farmers,investors,and entrepreneurs to improve the efficiency of food production and consumption in Africa.From precision farming to an efficient food supply chain,technology could bring major economic,social,and environmental benefits.Increasing investment and involvement of the private sector is crucial for the up-scaling of irrigation technologies.Indeed,the sheer optimism across the startup ecosystem is that extreme hunger can be cured in Africa,in this generation,by significantly transforming the industry that employs most of its citizens.This paper draws on lessons from past trends in the irrigation industry and emphasizes on novel directions to ensure that farmers,as well as other stakeholders reap the benefits associated with improved technologies.

关键词： food self-sufficiency irrigation development small-holder farms sub-Sahara Africa sustainability

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丘陵山区机械化灌溉现状与发展思考

排灌机械工程学报 2024年第3期42卷 294-303页

作者：朱兴业赵莹袁寿其刘俊萍汤玲迪江苏大学国家水泵及系统工程技术研究中心江苏镇江212013

针对目前丘陵山区机械化灌溉装备与技术单一,适应性差,缺少绿色化、智能化的灌溉模式等一系列问题,系统阐述了目前相关研究的现状和未来的发展趋势;全面了解目前丘陵山区机械化灌溉水平是后续开展相关研究的关键.通过分析目前丘陵山区... 详细信息

针对目前丘陵山区机械化灌溉装备与技术单一,适应性差,缺少绿色化、智能化的灌溉模式等一系列问题,系统阐述了目前相关研究的现状和未来的发展趋势;全面了解目前丘陵山区机械化灌溉水平是后续开展相关研究的关键.通过分析目前丘陵山区机械化灌溉的现状,适应丘陵山区机械化发展的要求,在机械化灌溉方面从国家政策入手到丘陵分区,结合丘陵山区的灌溉特点、目前的灌溉现状和相关经济因素进行了系统的总结.根据中国丘陵山区的国情以及相关政策,对丘陵山区机械化灌溉提出了相应的建议.可为未来丘陵山区机械化灌溉改造提供参考,补齐丘陵山区机械化灌溉装备与技术的短板,还可提高对丘陵山区机械化灌溉方面的重视,提升丘陵山区农业的灌溉水平,促进农业跨领域深度联合,推动农业可持续和现代化发展.

关键词：丘陵山区农业机械化灌溉装备机械化灌溉智能化