Improving Suction Performance of Centrifugal Pumps by Using Jetting Device

Improving the suction performance of centrifugal pumps by using jetting device is presented. The theoretical analysis, experimental study and engineering implementation show that suction performance of centrifugal pump can be improved with jetting device and be used for delivering the liquid media requiring high suction performance, whereas the efficiency and head of the pump will decrease a little. The effect of feed-back jetting on suction performance is the most obvious at design point. The suitable rate of feed-back flow is 2%-5%.

Numerical and Experimental Investigation of High-efficiency Axial-flow Pump

The experimental investigation of axial-flow pump has been rapidly developed to meet the needs of South-to-North Water Diversion Project of China. Owing to the boundary conditions of hub, blade tip clearance, much of the physical phenomena and laws involved in this complex flow field can＇t be fully determined. The flow characteristics of the high efficiency axial-flow pump have been simulated by RNG k-e turbulence model and SIMPLEC arithmetic based on FLUENT software. Numerical results indicate that the data from the prediction show agreement with the experimental results, static pressure on pressure side of blades increases slightly at circumferential direction with radius increasing, and keep almost constant at the same radial while increasing gradually from inlet to exit on the suction side along flow direction at design conditions. The static pressure, total pressure and velocity at inlet, impeller outlet and vane outlet were measured by a five-hole probe, and a contrastive experiment was done to investigate the influence of hub leakage. The experimental results show that inlet flow is almost axial and the prerotation is very small at various conditions. The meridional velocity and circulation distribution are almost identical at impeller outlet at design conditions due to steady flow and high efficiency. The residual circulation exits at downstream of the guide vane, and the circumferential velocity component increases linearly from hub to tip at small flow rate conditions. Hub leakage in adjustable blades results in the decrease of the meridional velocity and circulation at blade exit near hub. The results of numerical simulation and experiments supply important flow structure information for the high-efficiency axial-flow pump.

Design of the Control System of Adaptive Balancing Device Based on PLC

Due to the well condition and the un-expected imbalance movement of the pumping unit in use, the energy consumes a lot. The existing balancing equipment cannot adjust and monitor the pumping units in real time. Therefore this paper introduces the new adaptive balancing equipment—fan-shaped adaptive balancing intelligent device, projects a design of such control system based on PLC, and determines the principle of the control system, the execution software and the design flow. Site commissioning effect on Daqing Oilfield shows this fan-shaped adaptive balancing intelligent device can effectively adjust and monitor the pumping unit in real time, the balance even adjusts from 0.787 to 0.901, and integrated energy saving rate is 14.2%. It is approved that this control device is professionally designed, with strong compatibility, and high reliability.

Computational fluid dynamics of left ventricular assist device under unsteady flow

Left ventricular assist device( LVAD) in this study is a mechanical tool that is used to support blood flow in the patient with heart disease. It supports left ventricle by building up the pressure to the pump outlet connected to the aorta. This pump was designed based on the magnetic driven centrifugal pump with a unique small washout hole constructed inside the impeller to generate the washout flow passage to prevent the stagnation at the region underneath and around the rotor. Computational fluid dynamics( CFD) was adopted in this study to assess the performance and optimize the design to avoid recirculation and high shear stress which is the main cause of stagnation and blood damage. Transient simulation was used for this study due to the asymmetric design of the washout hole and the complication of the bottom support of the impeller that has a risk of thrombosis,also,it was used to predict the variation of hydraulic performance caused by the rotation of the impeller and pulsed flow at the pump inlet. The simulation results show no excessive stress and no recirculation observed within the computational domain; in addition,the research result also provides information for further optimization and development to the pump.

Combined Application of Circulatory Assist Devices Following Cardiac Arrest in Patients after Cardiac Surgery

Objectives To evaluate retrospectively the potential benefits of combined utilization of various assisted circulation devices in cardiac arrest patients who did not respond to conventional cardiopulmonary cerebral resuscitation （CPCR）. Methods Assisted circulation devices, including emergency cardiopulmonary bypass （ECPB）, intra-aortic balloon pump （IABP）, and left ventricular assist device （LVAD）, were applied to 16 adult patients who had cardiac arrest 82 rain-56 h after open heart surgery and did not respond to 20 rain or longer conventional CPCR. ECPB was applied to 2 patients, ECPB plus IABP to 8 patients, ECPB plus IABP and LVAD to 6 patients. Results One patient recovered fully and one patient died. Of the other 14 patients, 13 resumed spontaneous cardiac rhythm and one did not; none of them could be weaned from ECPB. Further treatment of the 14 patients with combinations of assisted circulation devices enabled 6 patients to recover. One of the 7 recovered patients died of reoccurring cardiac arrest after 11 days; the other 6 were discharged in good condition and were followed up for 3-49 months （mean =22 months）. Of the 6 discharged patients one suffered cerebral embolism during LVAD treatment, resulting in mild limitation of mobility of the right limbs ; the other 5 never manifested any central nervous system complications. There was no late deaths giving a 37.5% （6/16） long-term survival rate. Conclusions ECPB could effectively reestablish blood circulation and oxygen supply, rectify acidosis, and improve internal milieu. The combined utilization of ECPB, IABP, and LVAD reduces the duration of ECPB, improves the incidence of recovery, and offers beneficial alternatives to refractory cardiac arrest patients.

Quasi-Static, Poiseuille Flow of Analgesics from an Elastomeric Pump: Theoretical Determination of Infusion Times and Toxicity Conditions

Background: Elastomeric pumps (elastic balls into which analgesics or antibiotics can be inserted) push medicines through a catheter to a nerve or blood vessel. Since elastomeric pumps are small and need no power source, they fit easily into a pocket during infusion, allowing patient mobility. Elastomeric pumps are widely used and widely studied experimentally, but they have well-known problems, such as maintaining reliable flow rates and avoiding toxicity or other peak-and-trough effects. Objectives: Our research objective is to develop a realistic theoretical model of an elastomeric pump, analyze its flow rates, determine its toxicity conditions, and otherwise improve its operation. We believe this is the first such theoretical model of an elastomeric pump consisting of an elastic, medicine-filled ball attached to a horizontal catheter. Method: Our method is to model the system as a quasi-Poiseuille flow driven by the pressure drop generated by the elastic sphere. We construct an engineering model of the pressure exerted by an elastic sphere and match it to a solution of the one-dimensional radial Navier-Stokes equation that describes flow through a horizontal, cylindrical tube. Results: Our results are that the model accurately reproduces flow rates obtained in clinical studies. We also discover that the flow rate has an unavoidable maximum, which we call the “toxicity bump”, when the radius of the sphere approaches its terminal, unstretched value—an effect that has been observed experimentally. Conclusions: We conclude that by choosing the properties of an elastomeric pump, the toxicity bump can be restricted to less than 10% of the earlier, relatively constant flow rate. Our model also produces a relation between the length of time that the analgesic fluid infuses and the physical properties of the fluid, of the elastomeric sphere and the tube, and of the blood vessel into which the analgesic infuses. From these, we conclude that elastomeric pumps can be designed, using our simple model, to control infusion times while avoiding toxicity effects.

串联型心脏辅助装置Hemopump的仿真研究

目的研究Hemopump的辅助效果。 方法以理论分析和实验数据为基础 ,建立Hemopump动态的数学模型。将建立的泵模型植入到原有的犬的循环系统模型中 ,研究血泵和心血管系统的相互作用。结果Hemopump辅助可以提高心输出量 ,增加心脏的血氧供给 ,同时降低心肌的血氧消耗量。与主动脉内气囊反搏 (IABP)改善心肌供血平衡的机制不同 ,Hemopump主要通过降低左心室的前负荷来减少心肌的耗氧量。在一定范围内加快泵转速可以提高辅助效果。但是 ,泵的转速过高会影响泵的入流状况 ,导致辅助效果降低。结论仿真结果与动物实验及体外循环的测试结果一致。

Left Ventricle Failure and Blood Flow Estimation for Centrifugal Blood Pumps

This paper shows the blood flow control （FwC） performance to adjust rotational speed of an ICBP （implantable centrifugal blood pump） in order to provide an adequate flow to left ventricle in different patient conditions. ICBP is a totally implantable LVAD （left ventricular assist device） with ceramic bearings developed for long term circulatory assistance. FwC uses PI （proportional-integral） control to adjust rotational speed in order to provide blood flow. FwC does not use sensor for feedback, as there is an estimation system to provide blood flow measurement. Control strategy has being studied in a HCS （hybrid cardiovascular simulator） as a tool that allows the physical connection of ICBP during evaluation. In addition, HCS allows changes of some cardiovascular parameters in order to simulate specific heart disease： ejection fraction （10-25%） and heart rate （50-110 bpm）. FwC was able to adjust blood flow with steady error less than 2%. Results demonstrated that FwC is adequate to LVAD control irL different left ventricle failure conditions.

Experimental study on inlet vortex in pump sump

In order to study the mechanism of the vortex generation at the bottom of the pump sump below the flare tube,twenty pressure pulsation monitoring points were arranged at the bottom of the pump sump below the flare tube,and the pressure fluctuation experiments were carried out under different flow conditions.The experimental results show that the frequency of pressure fluctuation at the bottom of the pump sump is twice of the rotational frequency of the impeller blade.The vortex below the flare tube is easy to generate under the large flow conditions and mainly concentrates at the right front position below the flare tube.The position of the vortex occurring is corresponding to the position of the low-pressure region below flare tube.

Perioperative Nursing Management of an Animal Model of Axial Flow Blood Pump Implantation

This study aimed to explore the characteristics of perioperative nursing of experimental goats using self-made axial-flow blood pump implantation and provided theoretical nursing knowledge and practice-based evidence for the clinical application of domestically manufactured artificial cardiac pumps. Methods: Seven experimental goats were used in this study, three for pre-testing and four for the formal experiments. According to the surgical requirements for axial-flow blood pump implantation into the cardiac apex, we creatively designed and made a series of highly practical animal surgical instruments including a composite disassemblable bed for experimental animal transferring and monitoring, a multifunctional animal surgery bed, and portable medical supporting equipment. We also applied for two national invention patents and one utility model patent. Active measures were taken to ensure careful preparation before surgery, close collaboration during surgery, and effective management of complications after surgery. Results: Two of the four experimental goats died during surgery because of a massive hemorrhage caused by distal anastomotic failure and air embolism-induced cardiac arrest caused by air leakage from the outlet into the heart due to poor connection of the auxiliary pressure tap (used to measure left ventricular pressure). The mean survival time of the remaining three experimental goats was 22.7 hours. Conclusion: This study was the first to systematically and comprehensively investigate the perioperative nursing management of axial-flow blood pump implantation using animal models. These findings could greatly promote further clinical applied nursing research of self-made artificial cardiac pump implantation in experimental goats.

立式轴流泵装置叶轮与导叶间非定常流场分析

为了分析立式轴流泵装置叶轮和导叶体的非定常流场特征,采用ANSYS CFX对立式轴流泵装置全流道进行三维非定常数值计算,预测泵装置的能量性能,并通过物理模型试验进行验证。结果表明,各流量工况时,叶轮进口圆周测线的轴向速度分布均呈类正弦分布,波峰、波谷数与叶轮的叶片数相一致。小流量工况时,叶轮进口面的速度分布受叶轮的影响明显,速度加权偏流角与导叶体出口的平均涡角均最大。随着流量的增大,肘形进水流道的能量损失逐渐增大;导叶体的能量损失随着流量的增大呈先减小后增大的趋势,在最优工况时导叶体的能量损失最小,在小流量工况时60°弯管和虹吸式出水流道的能量损失之和最大。研究结果有利于立式轴流泵装置的结构优化与能效提高。

基于Java的排涝泵站站内优化调度软件开发

【目的】针对安装全调节轴(混)流泵的排涝泵站开发计算软件确定运行中的最优开机台数组合和各机组的叶片角度,以获得最高装置效率或最大流量。【方法】根据实测的扬程和电动机输入功率等运行参数,结合水泵性能曲线推算水泵流量和流道阻力参数,研究装置效率随叶片角度变化规律。以平均装置效率最高或总流量最大为目标函数,建立动态规划模型进行站内运行优化调度,获得最优的开机组合和运行机组的叶片角度。在集成环境IntelliJ IDEA下,采用Java开发了通用的可视化的计算软件。【结果】对某排涝泵站,通过软件获得并分析了装置效率随叶片角度(或流量)的变化曲线,给出了在Hsy=5.3 m条件下不同需要流量下的优化运行方案。当需要流量为32 m^(3)/s时,与各机组均以+1.0°叶片角度的简单决策方案相比,软件给出的优化方案装置效率提高了0.76%。【结论】实际工程应用表明所开发的软件性能稳定,计算精确,实用性强。

具有防融霜装置的蒸发器结霜特性及性能仿真研究

以具有防融霜装置的蒸发器为研究对象,建立基于理想最小防融霜补热量和结霜量无量纲关联式的空气源热泵动态模型,并依据实验数据验证其精确性,通过数值模拟分析不同环境参数对具有防融霜装置的蒸发器性能的影响。结果表明:后置式与跨越式系统蒸发器换热系数要高于前置式与传统电辅热系统,霜层厚度更小,分布更均匀;当相对湿度一定时,蒸发器换热系数随温度升高而增大;当空气温度不变时,换热系数随相对湿度的下降而减小,霜层更均匀;温度对蒸发器换热系数的影响比相对湿度更大。

水压泵柱塞密封性能实验装置的设计

为解决油水分离式柱塞泵的柱塞与缸套的密封可靠性及选型设计问题,研制了模拟水压柱塞泵实际运行工况的柱塞密封性能实验装置及其加载系统,并对实验装置进行了动平衡设计。在建立实验装置加载系统的仿真模型后,通过仿真对比确定了合理的加载方式。该实验装置的加载实验和稳定性实验表明,实验装置运行稳定可靠,且容积效率在合理范围内。

压差式和泵吸式施肥装置对棉花产量和氮肥利用率的影响

【目的】研究压差式施肥和泵吸式施肥两种施肥装置对滴灌棉田氮素吸收、棉花产量及氮肥利用率的影响,为新疆干旱区滴灌棉田水肥一体化技术提供理论依据。【方法】设置3个处理:不施氮(N_(0))、压差式施肥装置(N_(300)-压差式)、泵吸式施肥装置(N_(300)-泵吸式),其中氮肥为硫酸铵,用量为300 kg/hm^(2)。【结果】与N 0处理相比,N_(300)-压差式和N_(300)-泵吸式处理显著增加棉花总生物量、氮素吸收量和籽棉产量;与N_(300)-压差式处理相比,N_(300)-泵吸式处理滴头肥液铵态氮浓度分布更加均匀,且N_(300)-泵吸式处理棉花生物量、氮素吸收量、籽棉产量和氮肥利用率显著增加15.94%、31.50%、7.32%和52.98%。【结论】同一施肥量的条件下,泵吸式施肥装置滴头肥液铵态氮浓度随时间变化幅度比压差式施肥装置小,泵吸式施肥装置施肥均匀性优于压差式施肥装置,泵吸式施肥装置较压差式施肥装置促进棉花生长,且显著提高氮素吸收量及籽棉产量和氮肥利用率。

相同比转数轴流泵装置试验对比及选型应用

为了研究同一比转数轴流泵在工程中应用的适应性,依托淮河入海水道二期工程宋潮站的设计参数,采用了等流量加大扬程的选型方法初步选型,基于同一比转数轴流泵(TJ04-ZL-11,ZM60A)分别进行装置模型试验研究,对比分析了泵装置的能量、空化、飞逸等方面性能.结果表明,TJ04-ZL-11水力模型泵装置在叶片角度为0°、泵装置设计扬程为4.61 m时,效率为73.04%;在泵装置最高扬程为8.42 m时,效率为66.17%.ZM60A水力模型泵装置在叶片角度为0°、设计扬程为4.61 m时,效率为73.96%;在泵装置最高扬程8.42 m时,效率为71.14%.空化试验结果表明,ZM60A水力模型空化性能要比TJ04-ZL-11号水力模型空化性能更好.ZM60A水力模型飞逸特性与TJ04-ZL-11号水力模型飞逸特性相比差别不大.同一比转数的轴流泵在性能方面仍存在差异,在宽扬程运行范围的工程应用中需要兼顾空化、飞逸等多方面性能进行选型.研究结果对类似工程的水泵选型具有一定的参考价值.

立式轴流泵装置内流瞬变特性数值分析

为明确立式轴流泵装置内流瞬态变化特性,采用计算流体动力学(CFD)方法求解泵装置全流道内流场,并结合物理模型试验验证数值模拟的可靠性,得到不同流量工况下泵装置叶片区的瞬态流动特性。结果表明:叶轮进口偏流角较大的区域主要集中于叶轮前缘附近且随叶轮旋转呈动态变化,叶轮出口偏流角由轮毂向轮缘逐渐增大,导叶体出口偏流角较大的区域为导叶片尾缘周向位置。1.2 Q_(bep)工况时,叶轮进口轴向速度分布均匀度为89.5%,速度加权平均角为82.9°;当流量从0.8 Q_(bep)增加至1.2 Q_(bep)时,导叶体出口平均速度环量降低了12.1%;在流量工况为0.8 Q bep~1.2 Q_(bep)范围内,平均速度环量的最小值为4.7 m^(2)/s,此时流量为1.2 Q_(bep)。导叶体出口的涡结构特征显著,从导叶体进口到出口涡结构数量增多,涡体积减小,涡结构的合速度降低显著。

国产微型可植入式左心室辅助装置安全性和有效性的动物实验研究

目的 通过动物体内植入实验,测试研究一款自主研发的国产可植入式磁悬浮左心室机械循环辅助装置(Corheart 6)的安全性和有效性。方法 选取普通级雄性健康成年绵羊10只,常规全身麻醉后左侧第5肋间开胸,建立体外循环,植入Corheart 6,泵尺寸34 mm×26 mm,重量90 g。Corheart 6连接左心室及降主动脉进行左心室辅助。术后撤除体外循环,持续监测动物生命体征及Corheart 6运转情况。肝素静脉滴注维持活化凝血时间>500 s。观察动物整体存活情况、血液相容性情况并于实验终止时行心脏解剖病理分析。结果 10只绵羊术后心脏全部复跳,均能成功撤离体外循环辅助,8只动物术后正常存活到达预期实验终点(61~65 d),2只未到达实验终点,其中1只心肌组织意外进入血泵提前终止实验,另外1只于术后23 d死亡,死亡原因为肺部出血,与抗凝药物治疗有关。实验使用的Corheart 6泵运行良好,在整个实验过程中未出现自身原因导致的停机或其他运行故障。实验动物未发现有明显溶血,整体的血液指标都在正常范围内,未发现显著异常。8只存活至实验终点的羊,解剖取出的心脏大小和形态正常,且无明显的出血点与血栓形成,其余脏器也基本正常。血泵入口均无血栓形成,泵体内、泵出口也无明显的血栓形成与组织沉积,入口管与心尖顶环连接紧密无松动,血管保护套与泵出口连接良好,人工血管与主动脉段吻合良好。结论 在本动物实验研究中,Corheart 6表现了体积小、易于植入、性能稳定的特点,具有良好的血流动力学效果和良好的血液相容性。

移动DR床旁胸片对左心室辅助装置植入术后泵角度评估的可行性探讨

目的:探讨移动DR床旁胸片对左心室辅助装置植入术后泵角度评估的可行性。方法:回顾性搜集自2019年3月我院开展第三代连续流左心室辅助装置植入术临床实验以来,接受手术的患者共24例。根据全国放射科QA/QC学术研讨会纪要标准对所有患者术后当天、ICU期间连续拍摄的每张床旁胸片进行图像质量评级,测量等级为优的床旁胸片以及转出ICU后第1张心脏远达片的辅助装置流入管冠状角,以流入管冠状角作为泵角度的评估指标,比较术后当天与ICU最后1天测量结果的一致性,并评估观察者间测量结果的可重复性。比较ICU最后1天床旁胸片与心脏远达片流入管冠状角测量结果的一致性,并分析术后当天床旁胸片流入管冠状角与患者基线特征包括年龄、身高、体重、体表面积、体质量指数及术前左心室射血分数、左心室舒张末期横径、胸廓横径、术前心胸比率的相关性。结果:24例患者术后当天与ICU最后1天的冠状角[分别为(31.8±24.7)°和(30.0±24.6)°]差异无统计学意义(t=1.21,P>0.05);观察者间可重复性好(术后当天冠状角ICC=0.999,P<0.01;ICU最后一天冠状角ICC=0.997,P<0.01)。连续测量的冠状角大小变化主要受心影大小变化及投照体位的影响。ICU最后1天与心脏远达片冠状角[(32.1±26.2)°]差异无统计学意义(t=1.26,P>0.05)。冠状角仅与患者体重及体质量指数有弱的负相关性(r=-0.442、-0.554,P值均<0.05)。结论:24例患者ICU期间泵角度未发生明显变化,并且左心室辅助装置植入术后使用移动DR床旁胸片对泵角度进行评估是可行的,可以为泵角度的随访提供可靠的基础和依据;较低的体重及体质量指数可能与较宽的冠状角度有关。