Pump Flow Research Articles

Analysis and Experimental Study on the Internal Flow Performance of Deep-Sea Biological Pumping Sampler

To accurately acquire deep-sea live biological samples, a hydraulic suction macro-biological pressure-retaining sampler (HSMPS) was designed to achieve active capture of seafloor biological by a suction pump. The complex flow fields of deep-sea biologicals at three different locations were simulated. The deep-sea biologicals cause the flow field pressure and velocity to rise at different locations of the sampler, and the magnitude of the rise varies at different locations. The internal flow properties of the sampler were analyzed for different pumping flow rates the sampler. When the flow rate of the sampler pump was greater than 14 m3/h, the velocity of the inlet of the inflow area was greater than the limiting velocity of the deep-sea biologicals. The pumping test of deep-sea biologicals pumping sampler was carried out in the laboratory, and the test results were basically consistent with the simulation analysis. In order to balance the deep-sea biologicals damage and escape rate, the pumping flow of the sampler should be controlled between 14 and 16 m3/h. The test results provide a theoretical basis for the design of deep-sea biologicals sampling equipment.

Flow Characteristics and Pressure Pulsation Analysis of Cavitation Induced in a Double-Volute Centrifugal Pump

Cavitation is a complex multiphase flow phenomenon, and the generation of transient phase transitions between liquid and vapor during cavitation development leads to multi-scale vortex motion. The transient cavitation dynamics and centrifugal pump’s rotor–stator interaction will induce pressure fluctuations in the impeller and the volute fluid of the centrifugal pump, resulting in a complex flow field structure. Based on the Schnerr–Sauer cavitation model and SST k-ω turbulence model, this paper studies the transient characteristics of the cavitation-induced unsteady flow in the centrifugal pump and the excitation response to the pressure pulsation in the volute under different flow conditions, taking the large vertical double-volute centrifugal pump as the research object. The results indicate the following: As the impeller rotates, in the external excitation response, the jet-wake flow structure at the centrifugal pump blade outlet shows an increase in the blade frequency signal. This is evident near the measurement points of the volute tongue and separator. When severe cavitation occurs, the maximum amplitude at the blade frequency in the volute shifts from the pump tongue (30°) to the downstream of the tongue (45°). The value of fpmax is 3.1 times that when NPSHa = 8.88 m. By applying the Omega vortex identification method, it can be seen that the interaction between the vortices at the blade trailing edge and the stable vortex in the volute tongue undergoes a process of elongation, fusion, separation, and recovery. This represents the downstream influence of the impeller on the volute. When Q = 0.9Qd, the process of the blade passage vortex tail detaching and dissipating in the impeller flow path can be observed, demonstrating the upstream influence of the volute on the impeller.

Innovative fault diagnosis for axial piston pumps: A physics-informed neural network framework predicting pump flow ripple

Innovative fault diagnosis for axial piston pumps: A physics-informed neural network framework predicting pump flow ripple

CLINICAL EXERCISE PHYSIOLOGISTS IN THE INPATIENT SETTING – A CASE STUDY

https://youtu.be/i0pv5V6NKxM INTRODUCTION Preservation of functional capacity for patients admitted to the cardiovascular intensive care unit (CVICU) relies heavily on interventions prescribed by physical therapy. Traditional interventions are bed/chair exercises utilizing only body weight and ambulation around the unit. In this case, the clinical exercise physiologist (CEP) sought to push this standard of care to prepare a subject implanted with a BiVACOR total artificial heart (TAH) for orthotopic heart transplantation (OHT). This serves to present the methods in doing so and the need to further implement the role of clinical exercise physiologists in the inpatient setting. CASE PRESENTATION A 51-year-old male with history of chronic nonischemic cardiomyopathy, hypertension, diabetes mellitus, hyperlipidemia, and obesity presented to the hospital for right heart catheterization (RHC) in the setting of increased heart failure symptoms. Results of RHC led to admission and listing as UNOS status 4 for OHT. Hospital course was complicated by hypotension, ventricular tachycardia, and chronic kidney disease. Cardiothoracic surgery determined the need for mechanical circulatory support, a TAH as bridge to transplant. The patient elected to undergo implantation of BiVACOR, a TAH geared towards individuals with biventricular or univentricular heart failure where left ventricular assist device is not recommended. The patient is part of the BiVACOR Early Feasibility Trial in humans, approved by the FDA – he was the third human implant and would remain in hospital until OHT. The goal of the multi-disciplinary team was to preserve functional capacity during admission. MANAGEMENT Before implant, the patient’s 6-minute walk test (6MWT) distance was 320 meters, 2.52 METs. Post-implant in the ICU, the patient walked 1,800 feet 4 times per day. His 6MWT distance 13 days post-implant was 411 meters, 2.95 METs. By day 22 post-implant the patient progressed to recumbent bike cycling intervals. He was able to tolerate one 3-minutes interval and two 4-minutes intervals, split by 6-minutes rest intervals. His prescription was to cycle at 55-65 RPMs for 10-15 minutes three days per week with progression to 30 minutes continuously, 5-6 days per week. The patient was transplanted prior to completing any further sessions. During the cycling session, his blood lactate was measured at 5.2 mmol and hemoglobin 5.7 g/dL. His blood pressures remained stable, with normal responses to exercise, and pump flow increased from 8.9 L/min at rest to 12.5 L/min at peak exercise. Reported quadriceps muscle fatigue was the reason for session discontinuation. DISCUSSION Inpatient rehab goals of care should evolve to include various modalities of exercise that allow for more physiological adaptations, decreasing the impact of frailty and improving quality of life during admission. This patient’s case is an attestation to the growing need for exercise intervention prescribed by the CEP at all levels of care.

Numerical and Experimental Investigation of AC Electrothermal Flow Pumping in Microfluidic Devices: Influence of Electrode Pair Count on Velocity

Numerical and Experimental Investigation of AC Electrothermal Flow Pumping in Microfluidic Devices: Influence of Electrode Pair Count on Velocity

Gas–liquid separation mechanisms and bubble dynamics in a helical axial multiphase flow pump

Gas–liquid separation mechanisms and bubble dynamics in a helical axial multiphase flow pump

Percutaneous Microaxial Flow Pump in Cardiogenic Shock Complicating Acute Myocardial Infarction: A Meta-Analysis of Randomized Controlled Trials.

Percutaneous Microaxial Flow Pump in Cardiogenic Shock Complicating Acute Myocardial Infarction: A Meta-Analysis of Randomized Controlled Trials.

Alteplase Purge Solution for Impella 5.5 Ventricular Assist Device Purge System Occlusion: Case Report and Review of the Literature.

The use of an alteplase (Activase) purge solution to address Impella ventricular assist device "thrombosis" or "purge system occlusion" has been mainly documented with earlier generation Impella devices (CP, 2.5, 5.0). Here, we report the use of an alteplase purge solution to manage Impella 5.5 purge system occlusion in a 31-year-old male admitted to the cardiac care unit in cardiogenic shock and listed for a heart transplant. Throughout the purge system occlusion, the patient demonstrated hemodynamic stability and overall pump flow and cardiac output were preserved. Initially, there was a lack of response in purge flow and pressure observed at the lower concentration of alteplase purge solution (0.04 mg/ml), yet after using the alteplase 4 mg/50 ml purge (0.08 mg/ml) solution concentration, a response was seen. No bleeding or hemodynamic complications were observed. In addition, a suggested management workflow and review of the case reports and case series published to date regarding Impella purge system occlusion is included in this article.

FS-DDPG: Optimal Control of a Fan Coil Unit System Based on Safe Reinforcement Learning

To optimize the control of fan coil unit (FCU) systems under model-free conditions, researchers have integrated reinforcement learning (RL) into the control processes of system pumps and fans. However, traditional RL methods can lead to significant fluctuations in the flow of pumps and fans, posing a safety risk. To address this issue, we propose a novel FCU control method, Fluctuation Suppression–Deep Deterministic Policy Gradient (FS-DDPG). The key innovation lies in applying a constrained Markov decision process to model the FCU control problem, where a penalty term for process constraints is incorporated into the reward function, and constraint tightening is introduced to limit the action space. In addition, to validate the performance of the proposed method, we established a variable operating conditions FCU simulation platform based on the parameters of the actual FCU system and ten years of historical weather data. The platform’s correctness and effectiveness were verified from three aspects: heat transfer, the air side and the water side, under different dry and wet operating conditions. The experimental results show that compared with DDPG, FS-DDPG avoids 98.20% of the pump flow and 95.82% of the fan flow fluctuations, ensuring the safety of the equipment. Compared with DDPG and RBC, FS-DDPG achieves 11.9% and 51.76% energy saving rates, respectively, and also shows better performance in terms of operational performance and satisfaction. In the future, we will further improve the scalability and apply the method to more complex FCU systems in variable environments.

Association between hemolysis markers and neuron-specific enolase in AMICS patients supported with a microaxial flow pump.

Acute myocardial infarction complicated by cardiogenic shock (AMICS) is frequently preceded by out-of-hospital cardiac arrest (OHCA), with risk of anoxic brain injury. Neuron-specific enolase (NSE) is central to neuroprognostication; however, concomitant hemolysis can increase NSE independent of neuronal injury due to the presence of NSE in erythrocytes. This consideration is critical in AMICS patients treated with a microaxial flow pump (Impella, Abiomed), where hemolysis is frequent. We identified consecutive AMICS patients receiving microaxial flow pump support ≥6h from 2014 to 2022 in a tertiary Danish heart center. Peak NSE and hemolysis biomarkers within 72h following microaxial flow pump placement were used for analysis. Hemolysis was defined as plasma-free hemoglobin levels >31.5 µmol/L within 72h from device placement. The population was stratified according to the presence or absence of hemolysis.The final study population comprised 44 patients with eligible NSE and hemolysis biomarkers. The median NSE was 85 µg/L. Patients with hemolysis had significantly higher NSE levels than those without (115 vs. 69 µg/L, p=0.018). NSE levels were similar between OHCA and non-OHCA patients. No significant difference in death from anoxic brain injury was observed between patients with NSE levels above or below 60 µg/L. NSE revealed a significantly moderate correlation with all investigated hemolysis markers. NSE was associated with hemolysis, and not anoxic brain injury, in AMICS patients supported with a microaxial flow pump.

Performance of vortex pump in CFD simulations with rough walls

Flow passages in vortex pumps usually have rough walls. Precise consideration of wall roughness is an important issue in pump flow simulations. Numerical studies of the effects of wall roughness on the performance of vortex pumps are quite rare, especially with different interface models. Turbulent flows of water in a vortex pump with a specific speed of 76 are simulated using 1/8 and whole impeller fluid domains with rough walls, using the three-dimensional Reynolds-averaged Navier–Stokes equations, the standard k-ɛ model, and a scalable wall function in Ansys CFX 2019 R2. Equivalent sand grain roughnesses ks = 0.586 and 9.38 μm are determined for the chamber casing, volute, and suction pipe, and ks = 18.47 and 36.94 μm for the impeller by using the arithmetic average roughness Ra of the materials used in the pump and the correlation between ks and Ra given in the literature. The mixing loss along the interface between impeller and volute in the transient rotor model is determined. The rates of change of the head, shaft-power, and efficiency of the pump due to wall roughness are calculated. The transient rotor model with whole impeller domain and the frozen rotor model with 1/8 impeller domain for rough walls with Ra = 0.1 μm in the suction pipe, volute, and chamber and 3.2 μm in the impeller give the most accurate predictions of pump performance compared with experimental data. The transient rotor model with whole impeller domain gives more accurate predictions of pump performance than the frozen rotor model with 1/8 impeller domain. The mixing loss rises quickly at high flow rates. The transient rotor model with whole impeller domain gives plausible predictions of the rates of change.

Impeller wake transport along the diffuser midspan passage of an axial flow pump

Impeller wake transport along the diffuser midspan passage of an axial flow pump

Numerical investigation on leakage characteristics of labyrinth seal for cavitation flow in the liquid hydrogen piston pump

Abstract Based on the thermodynamic modified Zwart cavitation model a two-dimensional theoretical cavitation flow model of the labyrinth seal between a piston and cylinder in a liquid hydrogen piston pump is established and verified. The cavitation influencing on the pressure distribution along the clearance seal is analyzed, which would reduce the leakage rate of the clearance seal. input pressure and degree of subcooling influencing on the cavitation flow is discussed. in the larger inlet pressure and degree of subcooling can diminish the sealing effect between cavitation and liquid-phase flows. Furthermore, the leakage rates under clearance and labyrinth seals with 20-60μm sealing gap are compared, respectively. When the sealing gap is no less than 30 μm, the labyrinth sealing effect is superior to clearance seal. In the end, the leakage rate of labyrinth seals with three cavity structures: square, curve and triangle are simulated. The sealing effect are sequentially square labyrinth cavity, the curve cavity and the triangle cavity. The sealing effect is preferred when the optimal length-to-width ratio of the square cavity is around 5.0. The studies are further helpful to decrease the leakage rate of labyrinth seals and enhance volumetric efficiency in liquid hydrogen piston pump.

The characteristics of coarse particle solid–liquid two-phase flow and wear properties in deep-sea multistage mining pumps

The characteristics of coarse particle solid–liquid two-phase flow and wear properties in deep-sea multistage mining pumps

Energy dissipation of solid–liquid flow in a centrifugal pump based on an improved four-way coupling method

Energy dissipation of solid–liquid flow in a centrifugal pump based on an improved four-way coupling method

EMPLOYING THIN PLANAR ELECTRODES TO EXPAND THE IONIC WIND FLOW COVERAGE AREA AND ACHIEVE ENHANCED HEAT DISSIPATION

The suboptimal photoelectric conversion efficiency of light-emitting diodes (LEDs) leads to increased temperature. There is a growing interest in using microstructure ionic wind pumps to regulate the chip temperature. But the ionic wind flow and thermal transfer characteristics of thin-plate electrode pumps used for cooling LED chips is unclear. This study proposes ionic wind pumps equipped with wedged and zigzag emitters to effectively manage the heat generated by high-power LED chips. Experimental investigations were conducted to analyze the electrohydrodynamic characteristics of pumps with different emitter types. A two-dimensional model with a wedged electrode and a three-dimensional model with a zigzag electrode were developed for flow distribution analysis and energy efficiency comparison. The cooling capacity of pumps with different configurations was examined. The results show that the pump equipped with a zigzag electrode exhibits improved stability in corona discharge and approximately 1.53 times higher energy efficiency compared to the pump with a wedged electrode. Moreover, the pump with the zigzag electrode covers a larger ionic wind flow area, generating a higher intensity of ionic wind. The angle between the emitter and the grounding electrode significantly affects the ionic wind flow characteristics. The optimal angle is 70° for pumps with wedged emitters and 30° for those with zigzag emitters. Both pumps can produce a steady wall jet at their optimal angle, causing significant disruption in the surrounding area. The pump with a zigzag electrode exhibits superior cooling performance and is more effective with low power consumption.

Numerical study on the performance of an interventional microaxial blood pump with superhydrophobic surface

Unlike traditional blood pumps, interventional microaxial blood pumps are characterized by their small size, high rotational speed, and narrow gap between the impeller rim and pump housing. These features result in an unstable flow field within the pump, leading to high shear stress regions that can cause hemolysis. To improve the hydraulic efficiency of the blood pump and mitigate blood damage, this paper proposes an interventional microaxial blood pump with a superhydrophobic surface. The finite element method was used to model the axial blood pump and arterial flow field, with Navier slip boundary conditions applied to the impeller and outflow structure walls, simulating a slip length of 50 μm to represent the superhydrophobic surface characteristics. A combination of numerical simulations and hydraulic experiments was employed to evaluate the effects of the superhydrophobic surface on the pump's hydraulic performance and hemolysis characteristics. The results indicated that the designed interventional microaxial blood pump model demonstrated good blood compatibility. The superhydrophobic surface significantly reduced shear stress at the design point, with wall shear stress in the impeller and outflow structure regions decreasing by approximately 8.09%. Hydraulic efficiency increased by approximately 12.16%, and the hemolysis index decreased by about 12.60%. These findings provide valuable support for further optimization of microaxial blood pumps.

Methodology to compute the speed of pumps that fit the hydrodynamic levels in a well field

Pumping water from well fields is challenging for any water company, due to the restrictions attached to the aquifers’ hydrogeological characterisation. The difficulty is to set the speed of each pump allowing ensuring a quasi-uniform pumping from all wells in a field, at the highest flow rate that can be extracted from each well, paying attention to avoid clogging. In this paper we propose a methodology to compute the speed of each pump in a well field, corresponding to the desired pumped flow rate range, by keeping the requested hydrodynamic level in each well. The method is exemplified for a case study in Bucharest − a small well field, for which hydrogeological data are available. The nonlinear system of equations that defines the hydraulic system operation is solved in MATLAB for the stationary flow regime attained after reaching constant hydrodynamic levels in all wells. The numerical model of the well field is finally set and run in EPANET, within a dynamic analysis (simulation over an extended period of time), where water levels in the wells adjust to the extracted flow rate, according to the hydrogeological data. Two operating scenarios are discussed.

Research on flow characteristics of discharge pipe during reverse operation of bidirectional axial flow pump

Bidirectional axial flow pumps are of growing importance in flood control and irrigation. Reverse operation is a common concern during the operation of bidirectional pumps. Therefore, this paper focuses on studying the flow state in the discharge pipe of a bidirectional pump operating in reverse at various flow rates, utilizing model testing and numerical simulation methods. Research shows that the spiral flow in the discharge pipe leads to the high head measurements. Moreover, reverse operation generates vortices in the discharge pipe, with greater vortex intensity and range occurring at lower flow rates, causing poor velocity distribution uniformity. The concentration of vortex kinetic energy and energy loss in the discharge pipe is primarily within a range of twice the impeller diameter. Furthermore, as the flow rate decreases, the pressure pulsation in the discharge pipe becomes unstable. At design and large flow rates, the pressure pulsations are mainly due to impeller rotation; however, running at a small flow rate results in low-frequency fluctuations in the discharge pipe, occurring at a cycle time 3.5 times the rotation frequency. This research holds both theoretical and practical significance for enhancing the operational stability and efficiency of bidirectional axial flow pumps.

Optimization of drag-reduction microstructure parameters and study of the drag reduction mechanism in a rotating flow field

Fluid drag greatly lowers the efficiency and increases the energy consumption of underwater vehicles and devices working in similar environments. Therefore, drag reduction has become a major topic in fluids research. Inspired by the high drag-reduction effect of shark skin, this paper experimentally and numerically investigates the drag-reduction performance of a bionic shark skin microstructure with a triangular cross section. The structural parameters are optimized through numerical simulations. The microstructure reduces the drag by reducing the velocity gradient near the wall and changes the turbulent kinetic energy distribution in the flow field near the wall. Next, samples of microstructures were prepared using the template method. Experimental rheometer tests revealed a drag reduction rate of 14.29% on the microstructure surface under the set experimental conditions. Experiments and simulations have demonstrated the high drag-reduction effect of the microstructures within a rotating flow field. The developed method and theoretical basis for numerical simulations of rotating flow fields can be utilized in pump machinery such as magnetic levitation centrifugal flow pumps.