Pump Geometry Research Articles

Characterization of parametrically amplified spin wave resonances in thin YIG films

We have experimentally shown that the perpendicular pumping geometry is optimal for parametric amplification of thermal magnons, which form Spin Wave Resonances (SWR) modes in in-plane magnetized Yttrium Iron Garnet (YIG) films. Above the parametric instability threshold, the parametric SWR spectrum exhibits a second order nonlinearity: the effect of modulational instability at Continuous Wave (CW) pumping. The parametric SWR modes possess a high quality factor, Qf = 2.0 × 106 that is two orders of magnitude more than the Q factor of the Ferromagnetic Resonance (FMR) in high quality YIG films.

Enhancement of terahertz fields in LiTaO3 waveguides using a conical pulse front.

The development of methods for the generation of strong ultrafast electromagnetic pulses in the terahertz (THz) spectral range has led to a surge of progress in nonlinear THz spectroscopy and THz control of molecular and collective responses. For spectroscopy in the 1-THz range, the submillimeter wavelengths and associated large spot sizes, large optical elements, and short distances between final focusing elements and samples can lead to cumbersome experimental setups that are incompatible with some sample environments. Here, we introduce a novel terahertz ring excitation (TREx) optical pumping geometry to generate superposing, focusing fields in planar THz waveguides made out of the electro-optic material lithium tantalate. High THz fields, >175 kV/cm, are generated and measured optically with no free-space THz propagation. The field level achieved by pumping with a sequence of concentric rings of excitation light exceeds by about 20× the result of a single cylindrically focused line of pump light that has been used routinely in previous work. The technique opens new prospects for compact waveguide-based linear and nonlinear THz spectroscopy and signal processing.

Backflow at the inlet of centrifugal blood pumps enhanced by geometrical features

Extracorporeal life support (ECLS) includes life-saving support in severe acute cardiac and/or pulmonary failure. In the past 20 years, centrifugal pumps have become the primary choice to deliver the required blood flow. Pumps of various designs, with different approved operating ranges, are today available to clinicians. The use of centrifugal pumps in the low flow condition has been shown to increase hemolytic and thrombogenic risks of the treatment. Further, low flow operation has been associated with retrograde flow at the pump inlet. In this study, experimental and numerical methods have been applied to investigate the operating conditions and fluid dynamical mechanisms leading to reverse flow (or backflow) at the inlet. Reverse flow was predominantly observed in pumps having a top shroud covering the impeller blades, showing a relation between pump geometry and backflow. The shroud divides the pump volume above the impeller into two regions, separating the swirling reverse flow migrating toward the upper pump volute from the main flow, reducing the dissipation of the vortical structures, and allowing the swirling reverse flow to reach further in the pump inlet. At the inlet, backflow was observed as stable recirculation areas at the side of the pump inlet.

Toward an Adjustable Blood Pump for Wide-Range Operation: In-Vitro Results of Performance Curve and Hydraulic Efficiency.

Rotary blood pumps in Extracorporeal Life Support (ECLS) applications are optimized for a specific design point. However, in clinical practice, these pumps are usually applied over a wide range of operation points. Studies have shown that a deviation from the design point in a rotary blood pump leads to an unexpected rise of hemolysis with corresponding clinical complications. Adjustable pumps that can adapt geometric parameters to the respective operation point are commonly used in other industrial branches, but yet not applied in blood pumps. We present a novel mechanism to adjust the impeller geometry of a centrifugal blood pump during operation together with in-vitro data of its hydraulic performance and efficiency. Three-dimensionalprinted prototypes of the adjustable impeller and a rigid impeller were manufactured and hydraulic performance and efficiency measured (n = 3). In a flow range of 1.5-9.5 L/min, the adjustable pump increased pump performance up to 47% and hydraulic efficiency by an average of 7.3 percentage points compared with a fixed setting. The adjustable pump allows customization of the pump's behavior (steepness of performance curve) according to individual needs. Furthermore, the hydraulic efficiency of the pump could be maintained at a high level throughout the complete flow range.

Estimation of the performance of different pumps using non-Newtonian fluids in various operating conditions with artificial neural network

The performance of three centrifugal pumps designed to operate at a rotational speed of 151.84 rad/s and flow rates of 1, 25, and 45 kg/s is being investigated for both water and non-Newtonian fluids at various rotational speeds and flow rates. The analyses are being conducted experimentally and numerically within the flow rate range of 0.25–55 kg/s and rotational speed values between 52.36 and 151.84 rad/s. Additionally, artificial neural networks (ANN) trained using experimental pump performance data are being tested with experimental and numerical values obtained at a new rotational speed of 130.9 rad/s. The non-Newtonian fluids being tested include CMC 0.2% and CMC 0.4%, comprising carboxy methyl cellulose (CMC) solution and water. The results indicate that the pump's performance when handling non-Newtonian fluids is significantly influenced by the pump's geometry, rotational speed, and flow rate. In design parameters, the head obtained with 0.2% CMC for pump 1 is 3.3% greater than that in water. For pump 2, the highest head is in water according to design parameters. Pump 3 exhibits the highest head at a CMC of 0.4 in design parameters, and this value is 0.81% higher than the value with water. Experimental and numerical results demonstrate good agreement, especially in design parameters. The head obtained from numerical analyses with the RNG k–ε turbulence model for pumps 1, 2, and 3 at design parameters is 3, 10, and 9.83 m, respectively. The corresponding experimental heads are 3, 10, and 9.84 m, respectively. However, discrepancies between these results increase with higher flow rates and the use of non-Newtonian fluids. The compatibility of ANN results with experimental results is better than with numerical results, particularly at higher flow rates than the design condition. Pump performance values estimated by ANNs are 2% lower than the experimental results. This study provides comprehensive experimental data on the use of non-Newtonian fluids in different centrifugal pumps, and it also offers important guidance for future research by comparing ANN and computational fluid dynamics.

One-dimensional pump geometry prediction modeling for energy loss analysis of pumps working as turbines

Pumps as turbine (PAT) for small-scale hydropower, pressure relief valves, and hydro-pumping applications have recently gained popularity. In contrast to conventional turbines, pumps do not have movable guiding vanes to accommodate changes in flow rate and head. This limits their use to the single best operating point. As a result, the precise estimation of reverse mode operating parameters is critical. One of the most successful techniques in this regard is the energy loss model. However, it necessitates extremely detailed pump geometry and experimental data. Although it is claimed to be more accurate, the lack of data makes it impractical. This calls for the devising of a pump geometrical parameter prediction model from limited manufacturer information. Using 137 sets of commercial pump operating data, geometry redesign was carried out by MATLAB code. Following that, multivariate linear regression analysis was carried out, and a one-dimensional geometrical prediction model was developed. Then the result was validated with computational analysis and measurement. The model results were 99 %, 100 %, and 95 % correlated for pump inlet, volute, and throat inlet diameters, respectively, with the experimental results. Similarly, the model results were also 99 %, 71 %, and 89 % correlated for pump inlet, outlet, and volute blade width, respectively, with experimental results. The model gave a more accurate geometrical result than the analytical and numerical methods.

Influence of the centrifugal pump impeller vanes parameters on its energy performance at operating with high-viscosity liquid

BACKGROUND: The currently existing methods for recalculating the operation of centrifugal pumps for viscous fluids cover a sufficiently small range of viscosities. In addition, the considered papers cover the recalculation only, not the search for the optimal geometry of the centrifugal pump for high-viscosity liquids. In this paper, computational fluid dynamics tools were used to test the ability of centrifugal impellers to pump liquids with a viscosity of up to 20,000 sSt, as well as to search for the optimal geometry of the flow path.
 AIM: Determination the dependence pattern of the geometric parameters, including vanes, of the optimal geometry of the centrifugal pump flow path at various values of flow rate and viscosity.
 METHODS: A numerical modeling method based on the solving of discrete analogs of the basic equations of hydrodynamics is used in this paper.
 RESULTS: It was proved that, with the considered viscosities, an impeller with a profiled vane, but with a smaller wrap angle and height, is capable of more efficient operation than a disk impeller. The dependences of the parameters of the optimal flow paths on the characteristics for which their optimization was carried out are given.
 CONCLUSION: Based on the study results, it can be stated that it is advisable to use centrifugal impellers in case of high viscosity of the liquid, taking into account the choice of non-classical values of the geometric parameters of the flow path, including the height and angle of its vanes.

Multi-obective performance analysis of a wind power plant equipped with a PAT system

In conventional wind power plants, the wind turbine drives an electrical generator equipped with an AC/DC converter for battery charging purposes and with an inverter inverter to supply power to the grid / AC load. This approach exhibits some drawbacks like the energy losses associated to the power electronics and the cost and the waste management of the battery storage systems.To overcome such drawbacks, this work proposes a new plant scheme, where the battery system has been removed (or strongly reduced) and the storage task is accomplished by a pumping system equipped with a reversible hydraulic machinery which can operate both as centrifugal pump and a hydraulic turbine (called Pump as Turbine). In this scenario, when the wind velocity is quite high, the reversible hydraulic machinery, working as centrifugal pump, will store energy in the form of potential energy pumping fluid to an elevated water reservoir. On the contrary, in low wind conditions, the Pump as Turbine will operate as a hydraulic turbine, helping the wind turbine to overcome the external mechanical load. This solution results in a number of advantages: lower plant costs, longer Pump as Turbine life with lesser maintenance and reduced waste costs.The present work focuses on a multi-objective performance analysis of the proposed wind system power scheme. Specifically, this multi-objective sensitivity analysis will be addressed to the net potential energy stored by the reversible hydraulic machinery, the extracted wind energy and the torque supplied by the Pump as Turbine in hydraulic turbine mode. Such an analysis will considered as design variables the Pump as Turbine (centrifugal pump mode) specific speed (pump geometry), the gear box transmission ratio between the centrifugal pump and the wind turbine and the pump head. The aim of this analysis is to evaluate the design variables range which could lead to determine the set of the multi-objective wind systems optimal design.

Design and optimisation of an Intra-Aortic Shrouded rotor axial pump

Undesirable side effects in patients with a LVAD (Left Ventricular Assist Device) pump fitted include blood damage, thrombosis, blood traumatisation, and End-Organ Disfunctions. These side effects have generally been attributed to the high wall shear stresses and the induced turbulent flow. In this study, we introduce a novel design to address these effects by lowering the rotational speed and providing an optimum flow path design to minimise blood damage. We present an initial scheme for a new Intra-Aortic Shrouded Rotary Axial Pump and develop a sequence of pump geometries, for which the Taguchi Design Optimisation Method has been applied. We apply CFD tools to simulate the pressure rise, pump performance, hydraulic efficiency, wall shear stress, exposure time and mass flow rate. A prototype pump has been tested in a mock cardiovascular circuit using a water-glycerol solution. The optimum design delivered the desired pressure/mass flow rate characteristics at a significantly low rpm (2900 rpm). As a result, the estimated blood damage index is low, matching the design requirements. The theoretical performance was matched by experimental results.

Theoretical analysis about model simplifications and boundary conditions on two-phase flow instability of parallel heated tube systems

Flow instability may happen in both subcritical two-phase flow boiling systems (such as U tube natural circulation steam generator of Pressurized Water Reactor, once through steam generator of High-Temperature Gas-Cooled Reactor, etc) and supercritical evaporation systems. In previous theoretical researches, the model of a single heated tube (SHT) with constant pressure drop boundary condition (ConPD) was always used to investigate the system stability. However, in real applications, there are usually multiple parallel heated tubes (MHT) and unheated connection regions before the branch heated tubes. The system is usually driven by a pump, and there is always a long unheated main pipe and throttling between the heated tubes (boiler or steam generator) and the pump. However, there lacks rigorous analysis about the effects of these model simplifications and boundary conditions. Take superheated two-phase flow boiling systems as examples, the theoretical models with different flow-driven boundary conditions (ConPD, constant mass flow rate (ConMF), and pump driven (PumpD)), different numbers of heat tubes (SHT, MHT), with or ignoring the unheated region (UHR), with or ignoring the bypass of a pump, with identical or un-identical geometry parameters and operation parameters are established. Linear ordinary differential equations describing the instability are obtained. Eigenvalues of the coefficient matrix of linear ordinary differential equations, and the property of the block matrix and the similarity matrix are used to analyze the effects of the above boundary conditions and model simplifications on the system stability. Two new dimensionless numbers, dimensionless pump number (Npump) and dimensionless bypass number (Nbypass), are proposed to describe the effect of pump and its bypass on stability quantitatively. The effect of the pump bypass on the stability can be attributed to the decrease of Npump. No matter ConPD or PumpD is adopted, SHT considering UHR is proved to be more stable than SHT ignoring UHR. No matter UHR is considered or ignored, SHT with PumpD is proved to be more stable than SHT with ConPD. No matter UHR of MHT at the main pipe is considered or ignored, the stability of MHT with ConPD or ConMF or PumpD is proved to be the same as that of SHT with ConPD ignoring UHR. When ConPD ignoring UHR is adopted, the stability of MHT with un-identical geometry and operation parameters is proved to be the same as that of its most unstable heated tube. The above conclusions about the effect of model simplification and boundary condition are obtained from superheated two-phase flow boiling systems, they also hold for saturated two-phase flow boiling systems and supercritical evaporation systems.

Reverse Engineering Used to Profile a Gerotor Pump Rotor

In most situations, for the proper design of a gerotor pump, numerous parameters must be taken into account: the pump geometry, the properties of the materials from which the pumps are made (Young’s modulus, Poisson’s coefficient, friction coefficients, etc.), the hydraulic characteristics of the circulated fluids (fluid density, kinematic viscosity, etc.), the working performance of the pump (speed ranges, pressure, flow rate, etc.), with greater or lesser influence on volumetric efficiency, work capacity, or energy consumption. The paper presents a study regarding the inspection of the reciprocally enwrapping surfaces of the gerotor pumps using a three-dimensional measurement technique specific to reverse engineering, which involves 3D scanning of the pump components in gearing movement. The components were measured by means of a specific software (GOM Inspect) and compared, by overlap, with the CAD models made with the help of CATIA software (CATIA V5R21). At the same time, an analytical calculation algorithm was developed for the complementarity of virtual representations. Finally, the advantages of the reverse engineering technique compared to the developed theoretical algorithm and traditional CAD design are presented.

Directional planar antennae in polariton condensates

We report on the realization of all-optical planar microlensing for exciton–polariton condensates in semiconductor microcavities. We utilize spatial light modulators to structure a nonresonant pumping beam into a plano–concave lens-shape focused onto the microcavity plane. When pumped above condensation threshold, the system effectively becomes a directional polariton antenna, generating an intense focused beam of coherent polaritons away from the pump region. The effects of pump intensity, which regulates the interplay between gain and blueshift of polaritons, as well as the geometry of the lens-shaped pump are studied, and a strategy to optimize the focusing of the condensate is proposed. Our work underpins the feasibility to guide nonlinear light in microcavities using nonresonant excitation schemes, offering perspectives on optically reprogramable on-chip polariton circuitry.

A Numerical Study on Labyrinth Screw Pump (LSP) Performance under Viscous Fluid Flow

In this study, fluid viscosity effects on LSP performance in terms of boosting pressure were numerically investigated. A water–glycerin mixture with different concentrations corresponding to varying apparent viscosities was flowed through an in-house manufactured LSP under various flow conditions, e.g., changing flow rates, rotational speeds, and fluid viscosities. The pressure increment between the intake and discharge of the LSP was recorded using the differential pressure transducer. The same pump geometries, fluid properties and flow conditions were incorporated into the numerical configurations, where three-dimensional (3D), steady-state, Reynolds-averaged Navier–Stokes (RANS) equations with a standard SST (shear stress transport) turbulence model were solved by a commercial CFD code. With the high-quality poly-hexcore grids, the simulated pressure increment was compared with the corresponding experimental measurement. The internal flow structures and characteristics within the cavities contained by the LSP impeller and diffuser were also analyzed. The good agreement between the numerical results against the experimental data verified the methodology adopted in this study.

Non‐contact vacuum pumps

SummaryAn overview of the main methods for mathematical modeling of the working process of non‐contact vacuum pumps is given. The specifics and the main stages of mathematical model development for screw, scroll, claw and Roots vacuum pumps are considered. The results of mathematical modeling of pump characteristics are presented and compared with experimental data. The mathematical modeling technique presented here can be recommended for analyzing the influence of pump geometry and operating conditions on the pump characteristics of non‐contact oil‐free vacuum pumps.

Design and development of a peristaltic pump for constant flow applications

In wide-ranging areas, including hydraulics, biomedical, automotive, and aerospace, there is often a need to move a fluid with a constant flow rate. This is difficult to achieve with any type of pump and usually other elements are inserted to regularize the output. This study focused on the peristaltic pump because there are few studies on it and it has some interesting features, such as extreme simplicity, a small number of components, and the extreme compactness of the whole system. The first part of this study is focused on analyzing the classical geometry of the peristaltic pump to understand the origin of the discontinuity in the flow rate; the second part proposes a new geometry that mitigates the flow irregularity by more than 200%. In this way, it is possible to use it in all the sectors where a constant flow rate is required but where insulation between the fluid and the machine is required. Together with the flow study, an analysis of how the main geometric parameters affect the operation of the pump is provided, complete with explanatory graphs and tables. A prototype made through additive manufacturing technologies is also proposed.

P106: Computational Fluid Dynamics Improvements and In Vitro Tests of a Proposed Transventricular Axial Blood Pump

Heart failure is a chronic disease that affects thousands of people around the world, being characterized by the inability of one’s heart to adequately pump their blood according to their body’s needs. Its treatment may be performed through heart transplant. However, ventricular assist devices (VADs) can be used as a way to assist the patient while they wait for a transplant or as destination therapy, with them being responsible for the patients increase in the life expectancy. These devices are pumps that help supply the adequate cardiac output to the body. But the procedures used to implant this kind of device, the size and geometry of the pump are vital for the surgery success and assurance safety patient recuperation. Because of that many important researches center try to find pump geometry that comply these characteristics and comply human blood physiology. Then the reduction in size of these systems, which increases their reliability, biocompatibility and robustness, is essential to the complete implantation of the VADs, which is the main focus of the current state of art. In this sense, the objective of this project is to study the geometry of an Transventricular axial flow VAD to be implanted in the left ventricle. Considering the three rotors with different geometries proposed before, we get the best one and test the performance at the physical simulator designed. Previously the pump was printed on a resin 3D printer to perform in Vitro tests to compare the bench model with the computational model obtained. The designed rotor presented satisfactory results near the expected properties in terms of pressure and flow, which will probably generate low hemolysis. However, adjustments are still needed in the geometry to increase the rate flow vs rotation. The flow rate of 7 l/min obtained in the simulation at 4500 rpm was not reached in the printed model. The maximum flow rate achieved by the model printed in resin with the 3D printer was 4.8 l/min at a rotation of 5500RPM. In conclusion, this may have occurred due to the imperfection of the printed 3D model or really rotor improvements are needed. For this, the next step is to manufacture a steel rotor to perform new tests and verify the pump effectiveness. Therefore, further investigations and improvements to the model still need to be done.

Simple and compact high-power continuous-wave deep ultraviolet source at 261 nm based on diode-pumped intra-cavity frequency doubled Pr:LiYF4 green laser.

We report the recent progress on diode-pumped high-power continuous-wave Pr:LiYF4 (YLF) green laser and deep ultraviolet (DUV) laser generation via intracavity frequency doubling. Using two InGaN blue diode lasers as pump source to form a double-end pumping geometry, in this work, we have demonstrated a green laser at 522 nm with a maximum output power of 3.42 W, which is believed to be the highest power ever achieved in all-solid-state Pr3+ lasers in this specific spectral region. Moreover, by intracavity frequency doubling of the achieved green laser, we have further obtained a DUV laser at about 261 nm with a maximum output power of 1.42 W, which is far higher than previous results. The watt-level 261-nm laser paves the way towards the realization of simple and compact DUV source for a variety of applications.

Influence of Inlet Vane and Wrap Angles on Cavitation Behavior of a Centrifugal Pump

This comprehensive study focuses on the relationship between the inlet vane and wrap angles of a centrifugal pump impeller and its cavitation behavior. The objective is to propose a new design for cavitation performance enhancement of the pump by reducing the required net positive suction head (NPSHR). To render a detailed study, the variations of the mentioned angles were examined both at hub and shroud. A three-dimensional two-phase parametric computational fluid dynamics (CFD) study was conducted and variations of inlet blade and wrap angles at hub and shroud were investigated separately. After validating the experimental results with the pump model, the pump parameterization process was carried out, and pump geometry was re-defined with its geometrical properties. The characteristic curves of the parameterized pump and pump model were in agreement with each other. Numerical cavitation tests were performed and the NPSHR values of each design were calculated for four different operating conditions. Results showed that cavitation performance increase was achieved with angle variations at the best efficiency point (BEP) but, this situation led the pump to operate exposed to cavitation at high flows (HF) for some designs. Therefore, the design with the best cavitation performance increased at BEP and HF was proposed as a new design. During numerical simulations, shear stress transport (SST) turbulence model and Rayleigh–Plesset equation were used.

Hydrodynamic and radial force characteristics with design of a single-channel pump for wastewater treatment based on the similarity law

Single-channel pumps are widely employed for wastewater treatment in Korea. To render possible the application of this type of pump in other countries using different power frequencies, the present study applies the similarity law to redesign the impeller geometry of the single-channel pump optimized in a previous study. To this end, the numerical simulations are conducted using steady and unsteady Reynolds-averaged Navier–Stokes equations and a shear stress transport reattachment modification turbulence model. Numerical simulations are confirmed by an experiment based on the 11th API610 standard. At design flow rate condition, the novel pump model meets the design requirement with the minimum total head coefficient of 3.078. The distance between the center of the radial force and the origin of the new model is notably decreased in comparison with the reference model, especially at the design point with a reduction of 3.418 times. Moreover, the results of the unsteady radial force are consistent with those of the steady radial force. The pressure oscillations in the new model are likewise reduced compared to the reference model, particularly at several measuring points under design flow rate with pressure oscillations dropping from 8.5% and 10.1–5.3% and 1.2%, respectively. The non-uniform high-pressure region caused by the rotor-stator interaction at the outlet of the impeller is evidently suppressed in the new model. The new single-channel pump is feasible for new power frequency and performs better with low vibration and noise levels during the operation.

Experimental investigation on micro-ORC system operating with partial evaporation and two–phase expansion

This paper presents an experimental analysis conducted on a low-temperature micro-ORC energy system, to assess its performance operating with partial evaporation (PE-ORC). Temperatures of the heat source in the range between 40 °C and 75 °C have been tested, and for each value, the vapour quality at the expander inlet has been varied by regulating the feed-pump rotating speed. The thermodynamic state of the working fluid in two-phase conditions has been estimated by means of a thermal balance at the heat exchangers, using the measured values of temperature, pressure and flow rate.Detailed experimental results are provided, with special focus on the performance of evaporator, expander and feed-pump, highlighting the difference in their behaviour compared with the regular operation with dry expansion of the same micro-ORC system. Relevant improvements have been observed in the evaporator effectiveness, mainly due to the reduction of the pinch point temperature difference. Also, the volumetric and total efficiencies of the feed-pump are improved substantially. On the other hand, the net power output and the expander efficiency resulted penalized by the operation with partial evaporation. The maximum power output obtained was close to 1.2 kW, with heat source temperature equal to 75 °C and fluid quality close to 1. The power output is reduced, at constant temperature, by decreasing the vapour quality at the expander inlet.The results suggest that operating a small-scale ORC system with partial evaporation may lead to some improvements to the performance of the cycle, especially regarding the evaporator performance. Moreover, with values of fluid quality at the expander inlet between 0.8 and 1, the penalization on the expander performance, compared to the dry expansion mode, is limited. However, a proper redesign of the power plant for the specific purpose is required in order to make partial evaporation an effective solution. Specifically, the expander and pump geometry and control require to be optimized for the particular working conditions, the recuperator must be removed, and the evaporator should be designed for the optimal exploitation of the heat source.