Pump Rotational Speed Research Articles

Band application of slurry in orchards using a prototype spreader with an automatic rate controller

A prototype slurry spreader for band application in orchards was designed, constructed, and tested. The spreader comprised several components: 1) 5 m3 tank, 2) distribution device of trailing hoses to reduce ammonia emissions during application, 3) automatic rate controller to apply nitrogen per crop requirements, and 4) low-pressure, wide-section tyres to mitigate soil compaction and sward damage. The slurry tanker design fitted between tree row spacings accounting for tree shape differences. The spreading system consists of two groups of six trailing hoses; each hose group distributes slurry into two 1.0 m wide bands alongside the machine and 0.5 m from tree rows. Operator input of slurry total nitrogen content, determined by onboard hydrometer in the field, and target application rate in the control unit ensured that nitrogen was applied at a constant rate based on metering pump rotational speed as a function of machine forward speed. The rate control system was tested at different application doses and with rapid changes in machine forward speed (range of 3–9 km h−1). The machine responded promptly (<2 s) to forward speed changes, and the spreader evenly distributed slurry in both application bands (Dave < 2.5% on the treated surface). Band application of slurry by the trailing hose device reduced ammonia emissions by 63% compared to the common broadcast application system by splash plate.

Flow fluctuation behaviors of single-phase forced circulation under rolling conditions

Marine reactors are received increasing attention recently in the field of ocean engineering. The effect of platform motion on the coolant flow of an offshore nuclear power plants is very complicated, which is required further analysis. In this paper, effects of rolling motion on single-phase flow fluctuation with different loops were investigated experimentally. And a mathematical model was also developed to study the mechanism of the influence of rolling motion on flow fluctuation with different pressure head, rolling parameters and layouts of flow loops. For the closed loop, the flow rate was adjusted by two ways, i.e. regulating the pump rotation speed and changing the state of regulating valve. While for the opened loop, the pressure head was always supplied by elevated water tank. The Reynolds number ranged from 300 to 8000, and ranges of the rolling period and amplitude were 8–20s and 10–30°, respectively. The results show that increase of the loop resistance and pressure head results in smaller flow fluctuation amplitudes. Effects of rolling motion on single-phase flow fluctuation weaken as the oscillatory pressure drop decreases or the pressure head increases. If the pressure head is high enough, the effect of rolling motion on flow fluctuation could be neglected. Rolling motions influence the flow fluctuation behaviors in different ways for the opened loop and the closed loop, due to the inequable oscillatory pressure drop. The flow fluctuation model shows a good agreement with the experiments and the analyzing method is expected to other oscillating flow system.

The Research of Fuel Pressure Fluctuations within Diesel Injection Pump Cavity on Cam Shaft Rotate Speed

Fuel pressure fluctuations in a diesel injection pump cavity can affect the injection quantity balance. Among them, the injection pump rotational speed is a major factor affecting fuel pump fuel pressure fluctuations within the cavity. This article through the use of HYDSIM software for different speeds of volatility in fuel injection pump cavity pressures for Simulation.

Numerical Simulation of 3D Solid-Liquid Turbulent Flow in a Low Specific Speed Centrifugal Pump: Flow Field Analysis

For numerically simulating 3D solid-liquid turbulent flow in low specific speed centrifugal pumps, the iteration convergence problem caused by complex internal structure and high rotational speed of pump is always a problem for numeral simulation researchers. To solve this problem, the combination of three measures of dynamic underrelaxation factor adjustment, step method, and rotational velocity control means according to residual curves trends of operating parameters was used to improve the numerical convergence. Numeral simulation of 3D turbulent flow in a low specific speed solid-liquid centrifugal pump was performed, and the results showed that the improved solution strategy is greatly helpful to the numerical convergence. Moreover, the 3D turbulent flow fields in pumps have been simulated for the bottom ash-particles with the volume fraction of 10%, 20%, and 30% at the same particle diameter of 0.1 mm. The two-phase calculation results are compared with those of single-phase clean water flow. The calculated results gave the main region of the abrasion of the impeller and volute casing and improve the hydraulic design of the impeller in order to decrease the abrasion and increase the service life of the pump.

HeartWare Controller Logs A Diagnostic Tool and Clinical Management Aid for the HVAD Pump

Continuous-flow ventricular assist devices (VADs) are a viable therapy for the treatment of end-stage heart failure, offering support for bridge-to-transplantation and destination therapy. As support duration for VADs continues to rise, patient management and device maintenance will play an increasingly crucial role. The HeartWare Ventricular Assist System has currently been implanted in >4,000 patients worldwide. The HeartWare controller stores approximately 30 days of VAD data including pump rotational speed, power consumption, and estimated VAD flow. Routine assessment of controller log files can serve as a pump performance tool and clinical management aid, assisting the clinician to make accurate and timely diagnoses. Here, we discuss the controller's data collection system as well as present the process for evaluation and reporting of controller log files to clinicians.

Clinical evaluation of the Spiral Pump® after improvements to the original project in patients submitted to cardiac surgeries with cardiopulmonary bypass.

Objective The objective of this paper is to present the results from Spiral Pump clinical trial after design modifications performed at its previous project. This pump applies axial end centrifugal hydraulic effects for blood pumping during cardiopulmonary bypass for patients under cardiac surgery. Methods This study was performed in 52 patients (51% males), between 20 to 80 (67±14.4) years old weighing 53 to 102 (71.7±12.6) kg, mostly under myocardial revascularization surgery (34.6%) and valvular surgery (32.8%). Besides the routine evaluation of the data observed in these cases, we monitored pump rotational speed, blood flow, cardiopulmonary bypass duration, urine free hemoglobin for blood cell trauma analysis (+ to 4+), lactate desidrogenase (UI/L), fibrinogen level (mg/dL) and platelet count (nº/mm3). Results Besides maintaining appropriate blood pressure and metabolic parameters it was also observed that the Free Hemoglobin levels remained normal, with a slight increase after 90 minutes of cardiopulmonary bypass. The Lactate Dehydrogenase showed an increase, with medians varying between 550-770 IU/L, whereas the decrease in Fibrinogen showed medians of 130-100 mg/dl. The number of platelets showed a slight decrease with the medians ranging from 240,000 to 200,000/mm3. No difficulty was observed during perfusion terminations, nor were there any immediate deaths, and all patients except one, were discharged in good condition. CONCLUSION The Spiral Pump, as blood propeller during cardiopulmonary bypass, demonstrated to be reliable and safe, comprising in a good option as original and national product for this kind of application.

Numerical comparisons of the performance of a hydraulic coupling with different pump rotational speeds

A hydraulic coupling is a hydrodynamic device for transmitting rotating mechanical power. It is widely used in the machinery industry because of its advantages of high energy transmission efficiency, shock absorption and good adaptability, etc. In this paper, SIMPLEC algorithm and SST k-ω turbulence model were employed to simulate the steady state flows at operating conditions of two different rotational speeds (3000r/min and 7500 r/min) of the pump of a specified hydraulic coupling model. The results indicate the existence of similarity in the distributions of the flow fields between the two speeds, but the efficiency at the optimum condition is larger with higher rotational speed. It is concluded that the similarity principle of the efficiency of the hydraulic couplings does not apply in this case due to the relatively high rotating speed and small geometric specifications. It is also shown that the radially stratified pressure distribution on the torus section becomes more obvious with larger speed ratios, since the centrifugal movement plays more dominant roles over the circulating movement in these situations. When the speed ratio is small, with the completion of the circulating flow, the pressure distribution presents in a more circular pattern around the neutral zone of the torus section.

In Vivo Evaluation of Centrifugal Blood Pump for Cardiopulmonary Bypass—Spiral Pump

The Spiral Pump (SP), a centrifugal blood pump for cardiopulmonary bypass (CPB), has been developed at the Dante Pazzanese Institute of Cardiology/Adib Jatene Foundation laboratories, with support from Sintegra Company (Pompeia, Brazil). The SP is a disposable pump with an internal rotor-a conically shaped fuse with double entrance threads. This rotor is supported by two ball bearings, attached to a stainless steel shaft fixed to the housing base. Worm gears provide axial motion to the blood column, and the rotational motion of the conically shaped impeller generates a centrifugal pumping effect, improving pump efficiency without increasing hemolysis. In vitro tests were performed to evaluate the SP's hydrodynamic performance, and in vivo experiments were performed to evaluate hemodynamic impact during usual CPB. A commercially available centrifugal blood pump was used as reference. In vivo experiments were conducted in six male pigs weighing between 60 and 90 kg, placed on CPB for 6 h each. Blood samples were collected just before CPB (T0) and after every hour of CPB (T1-T6) for hemolysis determination and laboratory tests (hematological and biochemical). Values of blood pressure, mean flow, pump rotational speed, and corporeal temperature were recorded. Also, ergonomic conditions were recorded: presence of noise, difficulty in removing air bubbles, trouble in installing the pump in the drive module (console), and difficulties in mounting the CPB circuit. Comparing the laboratory and hemolysis results for the SP with those of the reference pump, we can conclude that there is no significant difference between the two devices. In addition, reports made by medical staff and perfusionists described a close similarity between the two devices. During in vivo experiments, the SP maintained blood flow and pressure at physiological levels, consistent with those applied in cardiac surgery with CPB, without presenting any malfunction. Also, the SP needed lower rotational speed to obtain average blood flow and pressure, compared with the reference pump.

Test sequencing problem arising at the design stage for reducing life cycle cost

Previous test sequencing algorithms only consider the execution cost of a test at the application stage. Due to the fact that the placement cost of some tests at the design stage is considerably high compared with the execution cost, the sequential diagnosis strategy obtained by previous methods is actually not optimal from the view of life cycle. In this paper, the test sequencing problem based on life cycle cost is presented. It is formulated as an optimization problem, which is non-deterministic polynomial-time hard (NP-hard). An algorithm and a strategy to improve its computational efficiency are proposed. The formulation and algorithms are tested on various simulated systems and comparisons are made with the extant test sequencing methods. Application on a pump rotational speed control (PRSC) system of a spacecraft is studied in detail. Both the simulation results and the real-world case application results suggest that the solution proposed in this paper can significantly reduce the life cycle cost of a sequential fault diagnosis strategy.

Simulation Study for the Effects of Rotational Speed on Performance of Full Metal Single Screw Pump

Rotational speed is one of the important parameters that impact lifting capacity of full-metal single screw pump .Firstly using the finite volume method to establish a full-metal single screw pump 3D model, secondly using FLUENT software to calculate outlet pressure changes with different series of rotational speed value of the pump in condition of the same inlet pressure .Lastly drawing outlet pressure change curves to evaluate the concrete effect of rotational speed on the performance of the pump. The results indicate that the lifting capacity of the pump and pressure bearing capacity of single stage increase with the rotational speed increasing. The centrifugal performance of the full metal single screw pump is more obvious. So it needs to give full consideration to the effect of rotational speed on characteristics of screw pump in the process of screw pump designing and using, especially the selection of pump series and rotational speed .Increasing the rotational speed of the screw pump can not only reduce the pump series and the structural size, but also can reduce the load torque, improve the reliability of drive system.Now,most of traditional rubber stator is cast one layer rubber that is of double helix surface in the metal enclosure, which can be used together with the metal rotor whose outer surface is plated by hard chrome, while working, the stator can be easily damaged because of the swelling, temperature expansion, and easy to aging of the rubber. As the stator is connected with the tubing, while the stator is damaged and we need to replace a new one, we should disassemble both the poles and string, and it leads to a high cost and the stator can not be used any more, which is apparently a great waste of resource. Besides, that the rubber in the inner surface is hard to clear is also one reason leading to the useless of the stator[1]. Full-metal single screw pump can avoid these shortcomings for its stator and rotor are made of metal materials and they take way of clearance fit. This can ensure the screw pump develops the higher working efficiency in normal operation. However the full-metal single screw pump developed quite late, its theoretical study and basic theory is less and not mature[2]. Rotational speed is the main parameter in the designing and using of full metal screw pump ,so in order to help improve the screw pump performance and for further study of the basic theory of metal screw pump, this paper will focus on the study of effect of rotational speed on the pump performance .

Transformation of vibration signals in rotary blood pumps: the diagnostic potential of pump failure

Although non-destructive and continuous monitoring is indispensable for long-term circulatory support with rotary blood pumps, a practical monitoring system has not yet been developed. The objective of this study was to investigate the possibility of detecting pump failure caused by thrombus formation through the monitoring of vibration signals. The data acquisition equipment included vibration pickups, a charge amplifier, vibration analysis systems, and exclusive hardware. A pivot-bearing centrifugal pump with a mock circuit was investigated for vibration analysis. To simulate the four common areas of thrombus formation, we used a piece of silicon attached to each of the following four locations: the total area of the bottom of the impeller, an eccentric shape on the bottom of the impeller, a circular shape around the shaft top, and an eccentric shape on the top of the impeller. Vibration signals were picked up, and the power spectrum density analysis was performed at pump rotational speeds of 2100, 2400, and 3000rpm. In this study, pump failure could be detected, and the types of imitation thrombi could be determined. We conclude that vibration detection with a computerized analysis system is a potentially valuable diagnostic tool for long-term circulatory support with rotary blood pumps.

アキュムレータを用いたアイドリングストップ方式による油圧源の省エネルギー

As a result of a shortage of energy resources such as oil and the need to protect the earth’s environment, energy saving efforts have been made in a number of fields. In the case of hydraulic equipment, energy saving in pump units is key because this unit is the major consumer of energy.Up to the present, variable-displacement hydraulic pump units (VD pump units) and inverter-control hydraulic pump units (INV pump units) have been widely employed. Here the authors propose the use of an intermittently operated hydraulic pump unit coupled with an accumulator (ACC pump unit) . In a previous report, the superiority of the ACC pump unit was demonstrated through an experiment using a modeled machine tool and a simplified load model. In this report, we compare electric power consumption, pump output pressure, rotation speed and efficiency of the VD pump unit, INV pump unit and ACC pump unit when hydraulic fluid is supplied to the load at a fixed flow rate. In addition, the effects of the accumulator volume and the pressure ratio between the upper and lower limits on efficiency and the ON-OFF switching period of the ACC pump unit are determined.

正規化終端インピーダンスの複素パラメータと油圧管路内圧力脈動の定在波の関連性

It is well known that the amplitude of pressure pulsation becomes extremely high when the frequency of the pump rotational speed coincides with the resonant frequency of the pressure pulsation standing waves. In the previous report, the authors investigated the relationship between the resonant modes of the standing wave arising in the connecting pipe and the termination characteristics of the hydraulic circuit. Although the influence of the two terminations, a restrictor and volume, on the resonant modes was clarified, the termination impedance contains only a real number or a purely imaginary number in terms of the complex characteristic. In this report, a further investigation of the influence of the complex parameters of termination impedance characteristics is undertaken. In particular, the non-dimensional pressure pulsation in the connecting pipe is examined by the numerical calculation to understand the resonant phenomena of a standing wave for the complex parameters of termination impedance. Consequently, the transition of the resonant mode between the “both ends closed” mode and the “pump end closed and termination end opened” mode is confirmed. The characteristics of the transition resonant mode are clarified, and it is found that pressure pulsation also becomes extremely high under the transition resonant mode conditions.

Using Intermittently Operated Oil Hydraulic Pump Unit with Accumulator to Save Energy

Efforts to save energy have been made in a number of fields due to a shortage of energy resources, such as oil, and a need to protect the earth’s environment. In the field of hydraulics, energy saving pump units are very important because of the energy they consume. At present, a variable displacement-type hydraulic pump units (VD pump unit) and inverter control-type pump units (INV pump unit) are widely used. In this paper, the authors propose using an intermittently operated pump unit coupled with an accumulator (ACC pump unit). First, the electric power consumption, pump output pressure, rotation speed, and efficiency of three types pump units are measured when the same work is done using a modeled machine tool. Next, the load is abstracted to clarify the general characteristics of intermittent work, and the electric power consumption and efficiency of each pump unit are measured. Finally, the static characteristics of each pump unit are measured, and it is verified that the ACC pump unit saves the most energy.

Effect of an ethanol–diesel blend on a common-rail injection system

This research paper presents a comparative experimental study for determining the functionality of a common-rail injection system used in light-duty diesel vehicles. Two Bosch fuel-injection systems were chosen to be tested using a low sulphur diesel fuel and an ethanol–diesel blend (7.7% v/v). Both systems were composed of a high-pressure injection pump Bosch (320 CDI), a common-rail and a Bosch piezoelectric fuel injector, and were tested during an accelerated durability test. In both cases, the injection systems were mounted in an injection test bench and run for 12 hours/day for 600 hours. An injection pressure of 1500 bar, a pump rotation speed of 2500 min−1 and an injection time of 1 ms were selected to simulate critical engine operating conditions. The selected test conditions were equivalent to driving a light-duty vehicle for over 120,000 km. This work employed several analysis equipment and techniques, including a surface tester for surface roughness characterization of the elements, an optical microscope for observation of the workpiece surface microstructure, a shadow comparator for geometrical characterization of elements, an analytical balance for weighing parts and, finally, a scanning electronic microscopy to determine nozzle dimensions. In both cases, the total fuel delivery was determined using an injection test bench. Results show that the use of the ethanol–diesel blend tested produced a similar effect on the durability of the injection pump parts as that produced when using diesel fuel. However, the effect on the injector nozzle was dissimilar.

Laser Flow Measurements in an Idealized Total Cavopulmonary Connection With Mechanical Circulatory Assistance

This study examined the interactive fluid dynamics between a cavopulmonary assist device and univentricular Fontan circulation. We conducted two-dimensional particle image velocimetry measurements on an idealized total cavopulmonary connection (TCPC) with an axial pump prototype intravascularly inserted into the inferior vena cava (IVC) and then in the IVC and the superior vena cava (SVC) for a dual-pump support case. The glass model of the TCPC consisted of rigid vessels having a diameter of 13.4 mm and a one-diameter vessel offset at the TCPC junction. Fluid velocity profiles were examined at a cardiac output of 3 L/min and SVC and IVC flow ratios of 30/70%, 40/60%, and 50/50% and pump rotational speeds from 3000 to 9000 rpm. In addition, cardiac outputs of 5 and 7 L/min were also examined. As compared to the flow profile with the pump present, the measured velocity field demonstrated the presence of rotational (i.e., out of plane) motion, which forced the higher-velocity regions toward the periphery of the vessel. As a result, few flow vortices were captured in the image plane downstream of the pump in the TCPC junction. However, the velocity profiles for all cases demonstrated the expected shunting preference of IVC flow toward the right pulmonary artery. Furthermore, the inclusion of the pump provided a pressure rise of 3 to 9 mm Hg, which would be sufficient to relieve systemic hypertension in Fontan patients with circulatory dysfunction.

What is the ideal off-test trial for continuous-flow ventricular-assist-device explantation? Intracircuit back-flow analysis in a mock circulation model

Bridge to recovery has become a major goal after left-ventricular-assist-device (LVAD) implantation thanks to recent development in adjunctive therapies. Precise assessment of native heart function under minimum LVAD support is the key for successful LVAD explantation. However, weaning of centrifugal LVADs normally generates diastolic intracircuit backward flow. This retrograde flow may become excessive load for the native heart during off-pump test. The flow itself is an inevitable characteristic of centrifugal pumps. Therefore, evaluating this retrograde flow in vitro is of considerable significance, even if its amount is different from that in clinical settings. The purpose of this study was to assess diastolic backflow of continuous-flow centrifugal LVADs in a mock circulation model. A centrifugal LVAD (EVAHEART, Sun Medical Technology) was installed in a mock circulation model by the left ventricle uptake and the ascending aortic return. Pump flow was measured at the pump rotational speed of 1000, 1500, 2000, and 2500 rpm, and pulse rate of the virtual native heart was varied to 60, 90, and 120 beats/min. After data collection, pump flow was integrated, and forward and backward intracircuit flow were calculated. As a result, nonphysiological reverse flow of approximately 2.0 L/min exists at the rotational speed, providing 0 L/min mean pump flow. An ideal off-test trial condition should be realizing both ± 0 L/min pump flow and no intracircuit backward flow at the same time. We are developing a novel EVAHEART drive mode that can change its rotational speed in synchronization with cardiac cycle with the aim of controlling this retrograde flow with the new drive mode and creating an ideal off-test condition.

An investigational study of minimum rotational pump speed to avoid retrograde flow in three centrifugal blood pumps in a pediatric extracorporeal life support model

During extracorporeal life support with centrifugal blood pumps, retrograde pump flow may occur when the pump revolutions decrease below a critical value determined by the circuit resistance and the characteristics of the pump. We created a laboratory model to evaluate the occurrence of retrograde flow in each of three centrifugal blood pumps: the Rotaflow, the CentriMag, and the Bio-Medicus BP-50. At simulated patient pressures of 60, 80, and 100 mmHg, each pump was evaluated at speeds from 1000 to 2200 rpm and flow rates were measured. Retrograde flow occurred at low revolution speeds in all three centrifugal pumps. The Bio-Medicus pump was the least likely to demonstrate retrograde flow at low speeds, followed by the Rotaflow pump. The CentriMag pump showed the earliest transition to retrograde flow, as well as the highest degree of retrograde flow. At every pump speed evaluated, the Bio-Medicus pump delivered the highest antegrade flow and the CentriMag pump delivered the least.

A110 油圧管路に発生する圧力脈動の定在波に関する研究 : 終端インピーダンスの影響(OS9 フルードパワーの基礎と応用2)

It has been well known that the amplitude of pressure pulsation becomes extremely high when the frequency of the sorce flow pulsation coincides with the resonance frequency of the standing waves. Therefore pump rotational speed or length of a connecting pipe should be designed so as to avoid the resonant modes of the standing waves. The final aim of this reserch is to establish design tips for these parameters and clarify the standing wave characteristics in hydraulic circuits. In this paper, particulary, the influence of the termination characteristics of the circuits on the resonant mode of the standing waves is investigated both numerically and experimentarlly.

油圧管路内に生起する圧力脈動の定在波に関する研究

In a hydraulic system, a displacement pump inevitably produces flow pulsation which becomes a main source of pressure pulsation. This source pulsation travels throughout the working oil in the passageways inside hydraulic components as an incident wave, and then is reflected by both of these components and the termination of a circuit. The standing waves of pressure pulsation arise from the interference of the incident and reflected waves. It has been well known that the amplitude of pressure pulsation becomes extremely high when the frequency of the source flow pulsation coincides with the resonance frequency of the standing waves. Therefore pump rotational speed or length of a connecting pipe should be designed so as to avoid the resonant modes of the standing waves. The final aim of this paper is to establish design tips for these parameters and clarify the standing wave characteristics in a pipe-line. In particular, the influence of the termination characteristics of the circuit on the resonant mode of the standing waves is investigated both numerically and experimentally.