潜水轴流泵内部流场压力脉动的数值模拟   总被引：1，自引：0，他引：1  

张玉新  ;王秀叶  ;丁鹏  ;唐学林 《排灌机械》2014,(4):302-307

流场压力脉动对轴流泵的运行稳定性具有重要影响,为了准确分析潜水轴流泵的压力脉动特性,采用RNG k-ε湍流模型和SIMPLEC算法,对ZQA系列潜水轴流泵进行了全流道三维流动数值模拟和压力脉动分析.计算结果表明：轴流泵的扬程、功率、效率等外特性计算结果与试验结果基本吻合;轴流泵内部叶轮进口截面压力脉动幅值最大,泵内的压力脉动的主要频率与叶片通过频率相同,导叶后的脉动以低频为主,叶片表面从轮毂到轮缘压力脉动低频成分逐渐减少;在叶片工作面,压力脉动的幅值从轮缘到轮毂逐渐减小,从叶轮进口到出口逐渐增大.叶片进水边轮缘处压力脉动的幅值是轮毂处的1.22倍.在叶片背面,叶片进水边轮缘处压力脉动的幅值是轮毂处的1.77倍,出水边轮缘处压力脉动的幅值是轮毂处的0.92倍,叶片背面的压力脉动幅值明显小于工作面;叶轮进口截面,在0.8Q工况流量下压力脉动最大,为设计工况的2倍.计算结果为进一步分析轴流泵压力脉动提供了参考.  相似文献   

泵输水管线水锤数值模拟及其防护研究     

吕岁菊  冯民权  李春光 《西北农林科技大学学报(自然科学版)》2014,42(9):219-226

【目的】分析泵输水系统因事故停泵引起的水锤问题,为泵站管线的安全运行提供参考。【方法】根据流体力学原理,建立有压管道非恒定流动的水锤数学模型,利用特征线法进行数值模拟计算;结合山西省庄头支线泵站的特点,在泵出口安装两阶段关闭蝶阀和沿管线布设空气阀的联合防护措施下,分析了其水力过渡过程。【结果】泵出口两阶段关闭蝶阀在快关 9 s/70°和慢关 63 s/20°时,水泵机组倒转转速由额定转速的1.41倍降低为无阀防护时的0.94倍,最大倒泄水量由93.47 m³降低到12.3 m³;在液控蝶阀和空气阀联合防护下,管线负压由－6.9 m降低为－2.0 m。【结论】通过合理控制蝶阀快慢关闭时间及角度,能显著降低水泵机组倒转和倒泄流量;调整空气阀布设位置、口径及进出口流量系数,可使沿线负压降低到管道承受范围之内,从而保证供水工程的安全稳定运行。  相似文献   

轴流泵装置反向发电的水力特性     

黄佳程  郑源  阚阚  许哲  黄从兵  周广新  杜贻钊 《排灌机械工程学报》2022,40(3):230-237

为探究某泵站轴流泵装置反向发电的水力特性,对该轴流泵装置反向发电工况进行全流道数值模拟分析.结果表明:轴流泵装置在额定转速进行反向发电时,其最优工况相比于水泵模式,水头和流量分别提高43％和38％;随着转速增大,效率-流量曲线呈现向大流量方向偏移趋势,高效区范围逐渐增大;导叶进口、转轮进出口压力脉动呈周期性,转轮进出口...  相似文献   

Natural forage composition decreases deer browsing on Picea abies around supplemental feeding sites     

Pablo Garrido  Sara Lindqvist  Petter Kjellander 《Scandinavian Journal of Forest Research》2014,29(3):234-242

In southern Sweden, maintaining high cervid densities through supplemental feeding has become a common management practice. We aim at investigating deer browsing pressure on young Norway spruce in relation to distance from supplemental feeding sites. Because available forage is considered important in understanding browsing patterns, we modeled several factors affecting food availability, and their interaction effect with distance. We confirmed earlier studies about a locally high browsing pressure on natural vegetation adjacent to supplemental feeding sites where browsing pressure declined with distance and alternative forage abundance. Novel is that browsing on spruce occurred in 27.6% of the investigated plots. The browsing pressure of those plots averaged 9%. Distance was the most important factor in relation to browsing. The interactive effect of occurring field layer (FL), and deciduous trees was also highlighted as these significantly affected the relationship between browsing pressure on spruce and distance. In the studied conditions, browsing pressure ceased at ca. 205 m, whereas in scenarios of an abundant FL, browsing levels were negligible already at 0 m from supplemental feeding sites. We suspect that most of the browsing was caused by fallow deer in our study area.  相似文献   

基于Pro/E的链式原条造材机锯截机构的设计     

侯朋杰  杨学春  刘瑞伟  王博文 《森林工程》2014,(2):84-87

实现自动化原木生产是提高贮木场原木生产效率和经济效益的重要措施.东北林区处于高纬度地区,常年低温寒冷,且目前我国尚未有适用于在低温户外作业的造材机,因此需要设计相关的造材机进行作业,提高东北林区木材资源的利用.主要根据贮木场的工作环境和效益,对链式原条造材机的锯截机构进行设计.通过计算及机械手册选取标准的零件,并运用Pro/E软件对锯截机构和关键零件进行建模,完成总体装配图.在建模的过程中介绍锯截机构的工作过程和各组成部分的作用.  相似文献   

复杂湿气集输管网清管时机的确定     

徐文龙  曾萍  王惠 《油气储运》2014,(3):279-282

在复杂湿气集输管网中,当管道实际运行压力、输量高于或低于管道设计运行压力、设计输量时,计算出的管道输气效率会出现大于100％或偏低的情况,使得管道清管周期的合理制定非常困难。为了确定管网的清管时机,制定合理的清管周期,减少清管作业频次,提出利用相对输气效率、管道始末端压差梯度、预测积液量与管容体积百分比、管道气体流速等参数综合分析判断管道清管时机的新方法。通过对苏里格气田集输骨架管网历次清管作业的分析计算,认为该方法符合现场作业的实际情况,可以准确判断出复杂湿气集输管道的清管时机,为现场清管周期的确定和清管方案的编制提供科学有效的依据。（表1,参6）  相似文献   

小压差换热器节流制冷脱水效果的影响因素     

张宁宁  钟志伟  张宇  李清方  郑峰  王传磊  唐建峰 《油气储运》2014,(4):408-411,417

为充分利用地层压力,大牛地气田集气站采用小压差换热器节流制冷法进行脱水。节流制冷脱水效果受多种因素影响,以换热器的换热效率和天然气露点为节流制冷脱水效果分析指标,选择集气站开展不同工况下的研究试验,分别分析了换热面积、输气量、二级节流压差和环境温度对换热效率和天然气露点的影响规律。结果表明：换热效率受换热面积和二级节流压差的影响较大,天然气露点受输气量和二级节流压差的影响较大。通过调节二级节流压差的方式,可以优化节流制冷脱水工艺,增强脱水效果。（图7,表2,参8）  相似文献   

锅炉供水/补水自动控制设计及应用     

万全福 《林业机械与木工设备》2014,(9):48-49

林区工业热水锅炉供水系统的电气设施落后,改进后使其具有了恒压自动供水／补水、超压自动泄水、自动报警等功能,并且自动化程度高,维护方便。  相似文献   

Doppler blood pressure measurement in pigs during anaesthesia     

Gabrielle C. Musk  Renata S. Costa  Jonathan Tuke 《Research in veterinary science》2014

To determine the accuracy of Doppler blood pressure measurement in anaesthetised pigs eight large white pigs (Sus scrofa) were anaesthetised with zolazepam and tiletamine as Zoletil 100 (4 mg/kg) and xylazine (2 mg/kg) by intramuscular injection followed by isoflurane in 100% oxygen. Blood pressure measurements were recorded using a Doppler probe on the radial artery and a catheter in the femoral artery connected to a transducer. The sample mean of the Doppler measurements were compared with the sample mean of the invasive systolic arterial blood pressure while accounting for the heart rate, end-tidal CO₂ and temperature. The predicted error of the Doppler was greatest when pigs were hypotensive and normothermic: 11 mmHg (CI: 6–15). Doppler measurements should be interpreted with caution in anaesthetised pigs that are hypotensive and normothermic.  相似文献   

Negative Pressure Wound Therapy: Experience in 45 Dogs     

Kathryn A. Pitt BS  DVM  MS  Bryden J. Stanley BVMS  MVetSc  Diplomate ACVS 《Veterinary surgery : VS》2014,43(4):380-387

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