Pump Chamber Research Articles

ДЕЯКІ АСПЕКТИ ПІДВИЩЕННЯ ЕНЕРГОЕФЕКТИВНОСТІ РОБОТИ ШАХТНИХ ВІДЦЕНТРОВИХ НАСОСІВ

Mine drainage systems, which are used at the main drainage of mining enterprises, have a drive capacity of up to 1600kW. To reduce non-productive energy losses, as well as for the continuous operation of the mining company, mine pumps must be energy efficient and reliable. Analysis of downtime of drainage systems shows that the weak point is the unloading device. This fact can lead not only to the failure of the pumping unit, but also to possible prolonged downtime of the mine. The main disadvantage of the existing disk unloading devices of mine pumps is their low reliability and low service life, due to the rapid wear of the components of the unloading unit. The most vulnerable elements of the unloading device are the unloading rings. The need for frequent replacement and adjustment of the elements of the discharge unit is associated with disassembly and assembly of the pump directly in the pump chamber. Such actions require significant costs of unproductive manual labor of service personnel, and rapid wear of parts of the unloading device necessitates their constant replenishment. Malfunctions in the unloading device can cause significant pump failures. To increase the reliability and energy efficiency of mine drainage systems, the method of control of the unloading device was used. During the experimental studies it was found that cavitation phenomena during the operation of pumping units are absent and, accordingly, can not be the cause of wear of the elements of the unloading unit. When the pumps are operating in steady state, the displacement of the rotors was monitored for 3-4 hours on each pump unit. After data processing, it was obtained that the wear of the surface of the unloading rings occurs at a rate of 0.05-0.15mm in one hour. To determine the wear of the rings of unloading during start-up - stop of the pump, at first the indicators of measuring devices at the established mode of operation of the pump unit were fixed. Then the pump was turned off and on again. After starting the pump unit, we made sure that the operating mode of the unloading device did not change and compared the readings of the shaft position indicator before stopping and after starting the pump. From the measurements made it followed that stopping and starting the pump does not lead to noticeable wear of the unloading device. Therefore, it can be assumed that mainly the wear of the discharge rings occurs during the steady operation of the pump unit.

Relationship between Axial Width and Flow Characteristics of Pump Chamber in Double Volute Centrifugal Pump

The axial width of pump chamber has a great influence on the flow characteristics of the pump chamber in the centrifugal pump. A single-stage single-suction double volute centrifugal pump with a semi-open impeller was selected as the object. For the 6 different pump chamber axial width, it was concluded that the pump chamber pressure at the different angles (0°, 90°, 180°, 270°) along the radial variation characteristics according to the contrast analysis of the pump cavity pressure field, velocity field distribution. The correlation between the pump chamber pressure and the impeller radius was revealed. The tangential velocity and radial velocity along the axial distribution curves were draw. The results show that when the axial width of pump chamber increases from 23.9 mm to 43.9 mm, the pressure value of the same radial position increases gradually. The radial pressure difference is decreasing. At the same axial width of pump chamber, the pressure mean increases along the radial approximately parabola. The tangential velocity of different angular directions has little difference in axial distribution. The mean of dimensionless tangential velocity in the turbulent core area decreases from 0.32 to 0.19 with the increasing of pump chamber axial width. The radial velocity varies is greatly along the axial direction. There are eddies at the directions of 0ånd 180°, but the mean of radial velocity in the turbulent core area is about 0. This research provides the reference for centrifugal pump hydraulic design, structural design and the accurate calculation of axial force.

Influence of Bingham fluid viscosity on energy performances of a vortex chamber pump

One of the problems in the development of coal-water technologies is the use of reliable and long-lasting pumps. To date, classic pumps, due to the use of mechanical moving parts and seals, are subject to rapid abrasive wear. The solution to this problem can lie in the creation of new vortex chamber pumps developed by the authors. They are highly reliable, simple in design and have no moving parts. The object of this paper consists in determining the range of vortex chamber pump performance when pumping Bingham fluids of different rheological parameters, as well as to determine the dependence of the pump efficiency on the Bingham viscosity and the yield stress. Study of the pump performance was conducted experimentally and with CFD simulation. It was found that an increase in the liquid viscosity reduces the vacuum value near the axis. For the first time it was found that the tenfold increase in plastic viscosity reduces the pump efficiency by about 20%. This results in the fact that the supercharger cannot pump the coal-water slurry with τ0>12 Pa and μB>1 Pa⋅s. The findings can be extended not only to coal-water slurry, but also to all Bingham fluids.

Experimental investigation of right‐left flow balance concepts for a total artificial heart

A total artificial heart (TAH) must be designed to autonomously balance the flows of the systemic and pulmonary circulation to prevent potentially lethal lung damage. The flow difference between the systemic and pulmonary circulation is mainly caused by the bronchial (arteries) shunt flow and can change dynamically. The ReinHeart TAH consists of only one actuator that ejects blood alternately from the right and left pump chamber. This design entails a coupling of the right and left stroke and thus, complicates the independent adaptation of the right and left flow. In this experimental study on the ReinHeart TAH, four concepts to keep the flows well balanced were investigated using an active mock circulation loop for data acquisition. Three concepts are based on mechanical design changes (variation of pusher plate shape, flexible right pump chamber housing, and reduced right stroke volume) to achieve a static flow difference. In combination with these static concepts, a concept influencing the ratio of systole and diastole duration to respond to dynamic changes was studied. In total, four measurement series, each with 270 operating points, to investigate the influence of circulatory filling volume, heart rate, bronchial shunt flow, and lung resistance were recorded. In the course of this study, we introduce a concept deviation indicator, providing information about the efficiency of the concepts to balance the flows based on changes in lung's blood pressures. Furthermore, the distribution of the measured data was evaluated based on bubble plot visualizations. The investigated variation of the right pusher plate shape results in high lung pressures which will cause lethal lung damage. In comparison, a flexible right pump chamber housing shows lower lung pressures, but it still has the potential to damage the lungs. Reducing the stroke volume of the right pump chamber results in proper lung pressures. The flow balance can dynamically be influenced with a positive effect on the lung pressures by choosing a suitable systole-diastole-ratio. The results of this study suggest that an adequate right-left flow balance can be achieved by combining the mechanical concept of a reduced right stroke volume with an active control of the systole-diastole-ratio.

3D design and numerical simulation of a check-valve micropump for lab-on-a-chip applications

In this paper, we concentrated on designing and simulation of check-valve micropump for on-chip applications. A series of simulations were carried out by using 3D two-way fully-coupled fluid structure interaction analysis in combination with Arbitrary Lagrangian-Eulerian (ALE) method to understand pumping chamber and inlet/outlet micro check-valves. After extraction of characteristic equations of each component, micropump main equation is solved to find time-domain pumping chamber pressure. Then, Effects of actuation amplitude and frequency on micropump’s flow rate were studied for different chamber sizes from 2 mm to 4 mm. In addition, the effect of backpressure on micropumps’ flow rate was evaluated. Using this method of simulation helps the researchers to estimate performance of micropump before initiating fabrication process.

Design, concept and first in-vitro results of the percutaneous, pulsatile left ventricular assist device-PERKAT LV

Abstract Introduction A very high morbidity and mortality is associated with cardiogenic shock due to left ventricular failure despite encouraging developments in interventional cardiology. Patients suffering from cardiogenic shock often require temporary mechanical circulatory support to stabilize organ perfusion. In addition, an increasing number of patients with complex multi-vessel diseases cannot undergo surgical myocardial revascularization as recommended by recent guidelines due to their comorbidities. Those patients could benefit from a protected PCI approach using a temporary mechanical assist device. The available LVAD systems have specific advantages and disadvantages. Purpose It was our aim to develop a percutaneous, pulsatile assist device that unloads the left ventricle in a physiologic way. Methods The PERKAT-LV (“PERkutane KATheterpumptechnologie”) device consists of a self-expanding nitinol pump chamber which is covered by foils. Those foils carry multiple outflow valves at the proximal part of the pump chamber. A flexible suction tube with a pigtail-shaped tip and inflow holes are attached to its distal part. The system is designed for 16F percutaneous implantation via the femoral artery. Pulling back the outer sheath unfolds the nitinol chamber in the descending aorta while the flexible suction tube bypasses the aortic arch and ascending aorta with its tip in the left ventricle. In the second implantation step, a standard IABP balloon is placed into the pumping chamber and is connected to an external IABP console. Balloon deflation generates a blood flow from the left ventricle into PERKAT LV. During balloon inflation, blood leaves the system through the outflow foil valves in the descending aorta. Positioning and schematic drawing of PERKAT-LV is demonstrated in Figure 1. Results Preliminary in-vitro studies using a prototype of the PERKAT LV device were performed. It was tested in different afterload settings (0, 40, 80 and 120 mmHg) using a standard 30 ccl IABP balloon and varying inflation/deflations rates (70, 80, 90, 100, 110 and 120/min). We detected flow rates ranging from 2.0 to 3.0 L/min depending on the afterload setting and inflation/deflation rate. Conclusion The novel percutaneously implantable and pulsatile working PERKAT-LV device offers left ventricular unloading and circulatory support of up to 3.0 L/min in a first feasibility study. At the moment, the system is extensively studied under in vitro conditions. First in vivo evaluation will follow in the near future. Based on the current results, we believe that the system is a promising novel approach for percutaneous application of temporary left ventricular mechanical support. Figure 1 Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): German Federal Ministry of Education and Research

Исследование влияния формы вихревой камеры на параметры работы вихрекамерного нагнетателя

На основе математического моделирования путем решения уравнений Рейнольдса с использованием SST-модели турбулентности выявлено влияние формы вихревой камеры вихрекамерного нагнетателя на его особенности работы и энергетические характеристики. Получено, что рациональной формой камеры является классическая цилиндрическая вихревая камера. Применение формы вихревой камеры отличной от классической приводит к снижению КПД на величину от 20 до 30%. Это происходит за счет значительного снижения коэффициента эжекции нагнетателя. Локальное уменьшение высоты вихревой камеры приводит к столкновению перекачиваемых потоков, что уменьшает расход всасываемой жидкости и уменьшает КПД. Локальное увеличение высоты вихревой камеры приводит к увеличению трения потока и к большим потерям энергии в вихревой камере.

Coupling Mechanism of Rotating Casing Effect and Impeller Structure of Roto-Jet Pump

An increase in internal pressure of a Roto-Jet pump is due to combined action of its impeller and rotating casing. Internal pressure of the pump chamber was determined according to outlet pressure of the impeller, and the influence of the rotary casing effect was ignored. To study the combined action mechanism of the rotating casing effect and impeller structure on the Roto-Jet pump, we used the open test bed of the Roto-Jet pump and four model pumps with impellers of different structures as research objects. We also conducted a comprehensive experimental study on the coupling mechanism between the rotating casing effect and impeller structure. Numerical calculation was performed to avoid the assumption of isotropic eddy viscosity, Reynolds stress linear pressure-strain model is selected, and the numerical calculation results are compared with the experimental results to verify its credibility. The results show that the rotating casing effect has multiple functions to reduce the friction loss of the disc, improve the pressure distribution inside the rotating casing, and increase the pump head. All scheme, pressure, and velocity fluctuations occur in the upstream and wake regions of the collecting pipe and the energy loss is concentrated in the upstream region. The difference in velocity distribution inside the collecting pipe is small and negligible. As long as the impeller and rotating casing continue to rotate synchronously, the liquid shear velocity at the same coordinate position of each scheme remains unchanged, and the liquid rotation angular velocity in the rotating casing is approximately 75% of the rotating casing which conforms to the rigid motion law. In the same scheme, the coefficient of uneven velocity inside the rotating casing gradually increases along the radial direction. The closer to the axis, the faster is the decrease of the peak tangential velocity and the velocity tends to be uniform. The size, shape, and position of the vortex core inside the rotating casing change constantly with various schemes. The distribution of vortex cores varies under each scheme. The front cover and rotating casing have a serious effect on the vortex core. The extremely poor analysis of the test results shows that the performance of the Roto-Jet pump is better when the closed impeller is rotated in synchronisation with the rotating casing. The advantages and disadvantages of each blade type can be determined according to the situation. The research results can exhibit the influence mechanism of the Roto-Jet pump shell effect. Selection of an impeller structure provides a reference.

A Theoretical and Experimental Study of a Piezoelectric Pump with Two Elastic Chambers.

The paper is a continuation of our work on the dynamic load in piezoelectric pumps. In the study, the dynamic load of liquid in the pipelines was proposed as a key factor that limits the output performance of piezoelectric pumps. To decrease the dynamic load, a piezoelectric pump with two elastic chambers was proposed in our previous published work. In this paper, the performance and key parameters of the piezoelectric pump with two elastic chambers were studied through theoretical analyses and experimental tests. After establishing the mathematical model of the piezoelectric pump with two elastic chambers, the paper theoretically analyzed the performance of the pump and the effect of different structural parameters on the performance. Then prototypes with a range of structural parameters were developed and tested. As revealed from the test results, the elastic chamber effectively decreased the dynamic load of the liquid in the pipelines and the flow rate of the prototype with two elastic chambers was higher than that of the prototype with one or no elastic chamber. However, the elastic chamber did not lead to the increase in the maximum output backpressure of the prototype. Adopting an elastic diaphragm exhibiting a smaller stiffness or a larger diameter could help decrease the dynamic load of the liquid. The elastic chamber more significantly impacted the flow rate of the piezoelectric pump with long pipelines. The pump chamber height had a significant effect on the output performance of the piezoelectric pump with two elastic chambers, which is consistent with the conventional piezoelectric pump. At the height of 0.2 mm, the flow rate of the prototype with two elastic chambers was peaked at 7.7 mL/min; at the height of 0.05 mm, the output backpressure reached the highest of 28.2 kPa. The dynamic load could decrease the amplitude of the piezoelectric vibrator, whereas the prototype with two elastic chambers could effectively reduce the impact of dynamic load on the piezoelectric vibrator. The flow rate decreased almost linearly with the backpressure. Under the same backpressure, the flow rate of the prototype with two elastic chambers was higher than that of the prototype without elastic chamber, and the flow rate difference between the two prototypes gradually decreased with the backpressure.

Deformation Mechanism and Control Technology of Surrounding Rock in the Deep-Buried Large-Span Chamber

The selection of the support scheme for deep-buried and large-span chambers has been a severe problem in underground engineering. To further study the mechanical mechanism of large deformation, based on the repair engineering of the chambers of Pingdingshan No.6 mine in China, the field investigation, laboratory test, numerical simulation, and theoretical analysis were studied. The surrounding rock of the central substation chamber (CSC) and the main pumping chamber (MPC) were classified according to the rock mass rating (RMR) classification method, and the main factors affecting the stability of the surrounding rock of the chambers were revealed. A prediction model of mechanical parameters of the surrounding rock was established based on the Hoek-Brown failure criterion. Additionally, the prediction results were used in FLAC3D to further analyze the failure of the original support scheme, and the feasibility of the restoration plan was proposed. Six key points of support technology for this kind of chamber were put forward. Comprehensive support and repair scheme, including “bolt, metal mesh, shotcrete, grouting, anchor cable, and combined anchor cable,” was put forward. The engineering practice indicated that the deformation rate was less than 0.7 mm/d, which was beneficial to the long-term stability of CSC and MPC. The implementation of this restoration project can provide a reference for other similar projects.

Improvement of the design of the aeration device of the pneumatic chamber pump

The production of building materials is a complex technological process involving the processing of raw materials with various physical and mechanical properties, as well as using a variety of degrees of complexity of technological equipment and auxiliary mechanisms. High-pressure pneumatic transport has found application in construction, refractory, chemical and other industries. It is widely used for transportation of fine-grained bulk materials such as cement, alumina, soda, apatite, ash, clay, synthetic products, mineral fertilizers. The process of pneumatic transportation occurs due to the action of compressed air on the material being moved. However, at the same time, as a rule, there are through channels in the material layer, which leads to an increased consumption of compressed air, part of the unloaded material remains at the bottom of the pump chamber, which reduces productivity. Due to the fact that some fluidizing devices can form through channels in the material layer and given the large volumes of material being transported, it is necessary to solve issues to improve the efficiency of pneumatic chamber pumps and reduce the consumption of compressed air required for transporting bulk materials. This can be achieved by organizing effective fluidization of the material, that is, uniform mixing of the transported material with air.

Experimental Investigation of Piezoelectric Micropumps with Single, Series or Parallel Pump Chambers

Three types of piezoelectric micropumps following different configurations: single, series, and parallel connection, are developed and investigated. All the micropumps are fabricated by wet etching technology and sealed by high temperature glass bonding. They share the same dimension characteristic of diffuser/nozzle microchannels. Verifying the impact of adding series or parallel connected pump chambers on single chambers, as well as verifying the performance of the flow rate, pressure and piezoelectric transducer vibration of three micropumps have been examined. Through the comparisons between three kinds of micropumps, the results show that the flow rate of the micropumps with parallel connected pump chambers have a higher flow rate than that of micropumps with single and serial connected pump chambers under the same driving conditions. In addition, both the flow rate and pressure with the serial micropump are the lowest. The pressure of the micropump with single pump chamber is larger than other kinds of micropumps at certain driving frequencies. Consequently, increasing the pump chambers cannot always increase the performance of the micropump. This coincides with the theory analysis. Finally, the vibration performance of piezoelectric transducers with three micropumps have been carried out. The parallel transducer has a higher vibration displacement than the other two kinds of micropumps. These results have great potentials for integration into labs with a chip or microfluidic driven systems.

A new structure of Tesla coupled nozzle in synthetic jet micro-pump

Synthetic jet pump is a potential technique to improve the pumping performance by introducing a smart structure which can enhance counter-rotating vortexes. Aligning with this approach, a new structure of valveless micro-pump is developed in this work. The mechanism of the present micro-pump is based on the combination of the nozzle and a tesla element to rectify the synthetic jet. The new structure of “ace of spades” nozzle, named Tesla coupled nozzle, creates series of vortexes at the orifice of the pump chamber that allows to attenuate the reversed flows while fluid is drawn through the pump. The present micro-pump is simple but robust and can perform at rather low voltages.

Ventricular reshaping with a beating heart implant improves pump function in experimental heart failure

ObjectiveThe left ventricle remodels from an ellipsoidal/conical shape to a spherical shape after a myocardial infarction. The spherical ventricle is inefficient as a pumping chamber, has higher wall stresses, and can lead to congestive heart failure. We sought to investigate if restoring physiological ventricular shape with a beating heart implant improves pump function. MethodsRats were induced with a myocardial infarction, developing left ventricular dilatation and dysfunction, and becoming spherical over 3 weeks. Thereafter, they were randomized to undergo left ventricular reshaping with a beating heart implant (n = 19) or continue follow-up without an implant (n = 19). Biweekly echocardiography was performed until 12 weeks, with half the rats euthanized at 6 weeks and remaining at 12 weeks. At termination, invasive hemodynamic parameters and histopathology were performed. ResultsAt 3 weeks after the infarction, rats had a 22% fall in ejection fraction, 31% rise in end diastolic volume, and 23% rise in sphericity. Transventricular implant reshaping reduced the volume by 12.6% and sphericity by 21%, restoring physiologic ventricular shape and wall stress. Over the 12-week follow-up, pump function improved significantly with better ventricular-vascular coupling in the reshaped hearts. In this group, cardiomyocyte cross-section area was higher and the cells were less elongated. ConclusionsReshaping a postinfarction, failing left ventricle to restore its physiological conical shape significantly improves long-term pump function.

Experimental study on wave-structure interaction of an offshore intake well with a curtain wall

ABSTRACT The present study focus on the wave-structure interaction of a caisson type offshore intake well with the regular waves. A 1:20 scale model is experimentally investigated with and without curtain wall in the shallow wave basin for its hydrodynamic responses like wave run-up, rundown, and free surface water oscillation inside the well. The wave run-up and rundown on all the faces record maximum when the scattering parameter (ka) is minimum. Moreover, the increase in relative wave height (H/d) results in an increase in the run-up on the seaward and shoreward faces. Besides, the free surface oscillation at the inlet and pumping chambers measures maximum when ka is minimum, and the influence of H/d keeps on reducing when the ka approaches the maximum value. The insertion of the curtain wall reduces the free surface oscillation at the pumping chamber when the relative water depth (d/L) ranges from 0.21 to 0.36.

An inverse Eikonal method for identifying ventricular activation sequences from epicardial activation maps

A key mechanism controlling cardiac function is the electrical activation sequence of the heart's main pumping chambers termed the ventricles. As such, personalization of the ventricular activation sequences is of pivotal importance for the clinical utility of computational models of cardiac electrophysiology. However, a direct observation of the activation sequence throughout the ventricular volume is virtually impossible.In this study, we report on a novel method for identification of activation sequences from activation maps measured at the outer surface of the heart termed the epicardium. Conceptually, the method attempts to identify the key factors governing the ventricular activation sequence – the timing of earliest activation sites (EAS) and the velocity tensor field within the ventricular walls – from sparse and noisy activation maps sampled from the epicardial surface and fits an Eikonal model to the observations.Regularization methods are first investigated to overcome the severe ill-posedness of the inverse problem in a simplified 2D example. These methods are then employed in an anatomically accurate biventricular model with two realistic activation models of varying complexity – a simplified trifascicular model (3F) and a topologically realistic model of the His-Purkinje system (HPS). Using epicardial activation maps at full resolution, we first demonstrate that reconstructing the volumetric activation sequence is, in principle, feasible under the assumption of known location of EAS and later evaluate robustness of the method against noise and reduced spatial resolution of observations.Our results suggest that the FIMIN algorithm is able to robustly recover the full 3D activation sequence using epicardial activation maps at a spatial resolution achievable with current mapping systems and in the presence of noise. Comparing the accuracy achieved in the reconstructed activation maps with clinical data uncertainties suggests that the FIMIN method may be suitable for the patient-specific parameterization of activation models.

Instability Mechanism and Engineering Cases of the Surrounding Rock in Deep High Stress, Weak Strata Chambers

ABSTRACT The surrounding rock of chambers under deep high stress conditions has the characteristics of a long deformation duration, large loosening range and large deformation. It is difficult to control chamber deformation with conventional support methods. The deformation and failure mechanism is as follows: strong creep of the weak rock in high stress conditions and gradual fracture of the support structures until support failure, and even roof collapse. On the basis of many years of engineering practice, this paper analyzes the strata pressure characteristics and instability mechanism of three typical pump chambers. The concept of the reconstructed bearing layer is proposed. These chambers include the −250 m pump chamber in Sino-Thai Company, 39 mining area pump chambers influenced by large faults in the Zhongmacun Coal Mine, and the −800 m pump chamber of the Zhaogu No. 2 Coal Mine. Combined with the reinforcement principle of the surrounding rock of chambers, a theory for rebuilding the bearing strata was proposed. Multiple supports on the basis of the New Austrian Law were suggested. As an example, multiple support technologies for the drainage pump chamber in the Zhaogu No. 2 Coal Mine were proposed. The primary support was combined with bolts, cables with high strength surface protection components. The secondary support of the surrounding rock was grouting, which can strengthen the strata. The third support was a double-deck I section rigid steel bracket. The fourth support was shotcrete, which can seal the strata. Field investigation showed that the surrounding rock of the drainage pump chamber was in a stable condition. The displacements of the walls, roof and floor were 28 mm and 5 mm, respectively, and the displacement rate was less than 0.2 mm per day. According to the usage situations of the three chambers, good technical and economic benefits have been achieved.

Compact, magnetically actuated, additively manufactured pumps for liquids and gases

We report the proof-of-concept demonstration of novel, valve-less, and magnetically actuated miniature (∼1 cm3) positive displacement pumps for liquids and gases—both single-material-printed pumps with embedded sintered magnets and the first monolithic, fully 3D-printed, multi-material magnetic pumps in the literature; a valve-less design greatly simplifies the pump’s operation and consumes less power compared to designs with active valves, and is less prone to clogging than designs with passive valves. The miniature diaphragm pumps are fabricated using 150 μm-thick to 225 μm-thick layers via fused filament fabrication; the structural parts are printed in pure Nylon 12, while the magnet that makes possible the actuation of the pump chamber is either monolithically printed in Nylon 12 embedded with NdFeB micro-particles or press-fit into the pump after single-material printing of the enclosing piston. The fabrication of the pumps employs a novel multi-material-compatible 3D printing process flow that monolithically creates all features with less than 13 μm of in-plane misalignment. Pump fabrication takes below 75 min to complete and costs under $3.89 in materials. The devices are driven by a rotating magnet and can deliver liquid flow rates as large as 7.88 ml min−1 at 198 Hz for sintered magnet pumps (N35 grade) and 1.68 ml min−1 at 204 Hz for the devices with monolithically 3D-printed magnets (∼N4 grade); the results surpass state-of-the-art, 3D-printed miniature liquid pumps. Actuation of a pump in excess of 14.4 million cycles shows no evidence of degradation, e.g. leaks. A pump with sintered magnet (N48 grade) was characterized as a vacuum pump using air as working fluid, achieving an ultimate pressure of 540 Torr in a 0.61 ml pumping volume and up to 9.3 ml min−1 flow rate at 230 Hz actuation; the results compare well with miniature, commercial, non-3D-printed vacuum pumps.

Simulation and Experimental Study of a Synthetic Jet Valveless Pump

A valveless microfluidic pump using a lead zirconate titanate (PZT) diaphragm actuated synthetic jet is developed and fabricated. For this present design, a valveless pump structure is developed in which the pump chamber is sealed on one side and connected to an emitting nozzle at another side. The design is simulated using the multiphysics approach and then successfully investigated with a prototype produced by a low-cost additive fabrication technique. The device's parameters, including the liquid pumping characteristics and the size of the PZT membrane, are optimized based on its desired performance. The developed device can be applied over a wide range of applications from micromixing to fluidic controlling.

Pearls and Pitfalls in Pediatric Fontan Operation Imaging

The Fontan operation or the total cavopulmonary connection is a palliative surgery for single ventricle congenital heart disease where the systemic venous return circumvents a pumping chamber and flows directly into the pulmonary circuit. With surgical and medical advances, there has been improvement in life expectancy of these patients, however, it has also resulted in unique complications from the physiology that requires diligent surveillance. A critical component relies on optimal imaging for diagnosis and treatment of these complications. This article describes the normal anatomy of the Fontan circulation, current imaging modalities and techniques, and frequently encountered complications seen when imaging the patients who have undergone Fontan palliation.