Disk Pump Research Articles

Energy efficiency prediction model and energy characteristics of subsea disc pump based on velocity slip and similarity theory

The variable-speed energy efficiency prediction model (EEPM) of subsea disc pump is the key to achieve double gradient in deepwater drilling, and it has also been the difficulty of pressure control matching and energy conservation. In this paper, the radial slip vortices are fully considered, and average slip method of circumferential velocity, relative velocity and absolute velocity at impeller outlet is proposed. Based on hydraulic energy loss and mechanical energy loss, the calculation method of theoretical head and similar parabola in similarity theory is improved, and EEPM is established. In addition, a new multifunctional test system and data processing model are designed to reduce the error. The experimental results show that the accuracy of EEPM is increased by about 4% when deviating from the rated speed by more than 20%, and the accuracy is about 99% within 20%. From the simulation, the flow passage is mainly a mixed-type movement, such as S-type double vortex and O-type single vortex. The turbulence kinetic energy near the volute tongue is the largest. The study improves the energy efficiency of drilling pressure regulation, and also provides a new perspective to the energy efficiency optimization and energy conservation of similar centrifugal pump and vortex pump.

Energy-efficient pressure regulation model and experiment of lift pump system in deepwater dual-gradient drilling

In order to improve the high-efficiency conversion between the pressure energy and the kinetic energy in the dual-gradient control of deepwater drilling, the energy-efficient pressure regulation model (EPRM) of the lift pump system (LPS) is established by energy efficiency prediction model of lift pump. Then the indoor and land-well similarity experimental platforms were designed. Indoor experiments show that when the deviation from the rated speed is more than 20%, the accuracy of the energy efficiency prediction model is improved by about 4%. The variable viscosity efficiency is more than 90% of the optimal from 40 m3/h to 75 m3/h, which shows that lift disc pump has good adaptability. Land-well experiments show that the average fluctuation error of inlet pressure is less than 5% with the flow change. During pressure regulation, the pressure fluctuation is less than 2.78%, and the minimum is 1.04%. In the pressure-increase and pressure-drop, the average pressure fluctuation is 1.445% and 2.02% respectively. For the pump with 2930 rpm, the regulation range should be controlled between 60% and 98% of the maximum speed, which can achieve more than 70% of the best efficiency. These make it possible to establish customizing targeted energy-efficient sections according to different actual drilling requirements.

Heat transfer enhancement by sinusoidal-shaped disk rotating in a forced flow

The geometric characteristics of the heat transferring surface and the outer flow conditions have a significant impact on heat transfer augmentation. Both, the surface roughness and the pressure gradient attribute to an enhanced heat transfer. These two effects are utilized in this study to enhance the convective heat transfer rate in a non-similar boundary-layer flow induced by the rotation of a sinusoidal-shaped disk in an external forced flow. The heat transfer coefficient is calculated numerically for the laminar boundary-layer flow with the help of the Keller-box method. The numerical solution of the governing system of equations is first validated by previous published (theoretical and experimental) results for a wavy rotating disk in the absence of an external flow field and also for a flat disk rotating in a forced flow. It is observed that the effect of surface waviness along with a relative fluid motion on heat transfer rate, shear stresses, and shaft torque is quite pronounced. Specifically, enhancement of moment coefficient due to waviness of the disk leads to increase the power of a wavy disk pump in comparison to a smooth one. Furthermore, 119%, 174%, 86%, and 86% enhancement in the heat transfer rate, the radial shear stress, the tangential shear stress, and the moment coefficient, respectively, is observed for a rotating wavy disk subjected to a forced flow (at fixed a/? = ? and a0/? = 0.125) in comparison to a free rotating flat disk.

A novel formulation and analysis for heat transfer in von Kármán flow involving viscoelastic fluid: OHAM solutions

This research concentrates on the von Karman flow of viscoelastic fluid obeying second grade model over a heated permeable disk. Our interest is to explore how fluid motion triggered around the disk is affected by the existence of both elasticity and viscous dissipation effects. It is found that the problem exhibits self-similar solution only when a prescribed wall temperature distribution is considered. Series solutions are worked out by using an easy to implement yet reliable routine BVPh 2.0 of MATHEMATICA based on the homotopy analysis method. The total squared residual of the system is evaluated which illustrates that the approximate solution accurately matches the exact solution at sufficiently higher order of approximation. The influence of parameters on the disk pumping efficiency and resisting torque is also deliberated. Graphical results reveal a marked formation of momentum/thermal boundary layer provided that the viscoelastic fluid parameter is sufficiently large. An important outcome is that the elastic effects of fluid tend to reduce the torque required to main disk rotation. Moreover, flow behavior near the disk is substantially altered by wall suction effect. Entrained flow is predicted to accelerate whenever elastic effects are present.

Analytical Methods and Verification of Impeller Outlet Velocity Slip of Solid–Liquid Disc Pump with Multi-Type Blades

The intensive exploration to improve the accuracy of the calculation model of velocity slip and theoretical head has always been a major issue in pump research. Discontinuous blade of disc pump is different from the continuous blade of traditional pump. Disc pump realizes energy transfer by the effect of boundary layer. In order to fill in the theoretical blank of current research on the velocity slip and theoretical head of blade disc pump, the velocity slip is calculated by the systematic analysis under solid–liquid flow. In this study, the current misconception of velocity slip was corrected. Based on the different normal velocity components between particle and liquid on the blade surface, a new method is proposed to further verify the difference of solid–liquid flow velocity in impeller passage. Through the proposed method of calculating average circumferential velocity, the calculation model of the velocity slip coefficient and theoretical head of disc pump with linear and curved blade are given and verified. The accuracy of calculation model is increased by 39.4%. This model has good application value in theoretical head calculation, which lays a foundation for further research on energy conversion, energy efficiency prediction and reverse optimization design of disc pump with different blade shapes.

Test Procedure for a New Type of a Ventricular Assist Device Based on a Viscous Friction Pump

Introduction. Currently, the possibility of effective correction of multiple organ failure and increasing the life expectancy of patients with critical heart failure using the ventricular assist devices (VAD) is absolutely evidenced. The development of alternative analogues of such devices produced within the country has been an urgent problem for many decades. The design of this machine requires the development of a protocol for carrying out complex biomedical studies on the biocompatibility and safety of the new device.The aim of the study was to develop a protocol for testing and conducting comprehensive biomedical biocompatibility studies of a new ventricular assist device in an acute animal experiment.Materials and methods. The study to develop a technique for implanting a left-ventricular assist device (LVAD) in an acute experiment included female mini-pigs, weighed 40-60 kg. In a series of acute experiments, 5 implantations of a disk pump as a LVAD were performed with a maximum observation period equal 6 hours.Results. In the series of acute experiments, an implantation technique was developed and the fundamental possibility of a viscous friction pump application as a ventricular assist device was evidenced. In all experiments (n = 5), the average level of free hemoglobin did not exceed 2.6 mg%, which supports safety of performance of the viscous friction pump regarding blood erythrocytes. None of the experiments recorded episodes of pump shut-off or breakdown.Conclusions. The series of acute experiments on mini-pigs helped reveal a number of anatomical and physiological features of this animal species that significantly complicated implementation of persistent observation. However, the developed experimental LVAD test methodology can be recommended for use in further chronic experiments on large laboratory animals (calves).

A study of heat transfer and entropy generation in von Kármán flow of Reiner-Rivlin fluid due to a stretchable disk

Present paper concentrates on viscous heating effects in fluid flow along a stretchable rotating surface in a Reiner-Rivlin fluid. Heating process of the disk is based on a quadratic surface temperature distribution. After invoking boundary layer assumptions, a self-similarity solution is assumed resulting in a coupled non-linear system. This system is evaluated numerically by a collocation method based MATLAB package bvp4c. Computational results reveal a marked formation of boundary layer provided that cross-viscosity coefficient is sufficiently large. Asymptotic solutions (for large axial distance) are derived by computing eigenvalues of the system at an equilibrium point. Some associated concepts such as moment coefficient (measuring the resisting torque), radial wall shear, disk pumping efficiency and heat transfer rate are critically scrutinized in the light of new physical attributes namely cross-viscosity coefficient and radial stretching in this research. Furthermore, second law of thermodynamics is utilized to investigate entropy production rate in the boundary layer. A noteworthy finding is that moment coefficient in von Kármán flow is substantially lowered when fluid exhibits non-Newtonian effects. Entrained flow is predicted to accelerate whenever radial stretching is considered.

Tesla Bladed Pump (Disc Bladed Pump) Preliminary Experimental Performance Analysis

A preliminary experimental work on a centrifugal pump model specifically designed to transport slurry and multiphase flows is presented. The impeller design corresponds to the so-called “Tesla Bladed Pump” adapted from an existing DiscflowTM pump design for the petroleum deep-sea application. The overall performance results of such a specific pump design are presented for different rotational speeds and discussed in relation to affinity laws coefficients. The results show that the performance of the tested disc pump strongly differs from the conventional centrifugal bladed pump. A one-dimensional approach using complete Euler relation is used to explain the differences in the present case. Moreover, it has been found that available results in open literatures do not correspond to the real optimum conditions, more detailed research work must be performed to get a better understanding on this kind of bladed disc pump.

First experience in implantation of a mechanical circulatory support device based on a disk-type pump: an acute experiment

Objective: to carry out the implantation of an artificial left ventricle of the heart based on a disk-type pump in an acute experiment on a large mammal (mini-pig). Materials and methods. To test the surgical technique of implantation and assess the biocompatibility of the apparatus for mechanical support of blood circulation based on a viscous friction pump, an acute experiment was conducted on an animal. A large mammal (mini-pig weighing 90 kg) was used as an experimental model. The implantation of the pump was performed extracorporeally according to the scheme «the apex of the left ventricle – the descending thoracic aorta». During the experiment, invasive blood pressure, central venous pressure, cardiac arrhythmias, body temperature, blood gas composition, activated coagulation time were monitored. Under the control of transesophageal echocardiography, the pump operation mode was set with parameters – speed 2400–2600, productivity 4 ± 0.5 l/min, average IAD – 70–80 mm Hg. Results. In the course of the experiment, the fundamental possibility of using the developed disk-type pump as a device for supporting blood circulation was proved. For 4 hours, the pump provided adequate hemodynamic parameters with an average productivity of 4 ± 0.5 l/min and 2500 rpm. After 4 hours of operation of the pump in the conditions of inactivated heparin (AST – 114 sec), no blood clots were found between the pump disks. Conclusion The hemodynamics feature of the disk pump allows you to develop sufficient performance parameters to ensure adequate blood circulation. The mechanism of action of the «boundary layer» minimizes the risk of blood clots in the pump cavity. However, the topographic and anatomical features of the pig’s body do not allow experiments with a long observation period.

Регуляризованные уравнения гидродинамики в задаче моделирования дискового насоса и их реализация в рамках программного комплекса OpenFOAM

Регуляризованные уравнения гидродинамики в задаче моделирования дискового насоса и их реализация в рамках программного комплекса OpenFOAM

Modifying the surface of a titanium alloy with an electron beam and a-C:H:SiOx coating deposition to reduce hemolysis in cardiac assist devices

The use of implantable mechanical pumps to support stable heart function saves lives to a large number of patients. The priority goal of research in this area is to develop advanced pumps that will ensure minimal injuries and fractures of blood cells. A combined method of modifying the surface of disk pump parts made of titanium alloy VT-6 has been developed to reduce blood hemolysis. The method includes material pretreatment with a high-current low-energy electron beam and plasma-enhanced chemical vapor deposition of a-C:H:SiOx coating. The effect of such electron beam parameters as the energy density and the number of pulses on the surface morphology, hardness, plasticity index, friction coefficient and wear rate of the titanium alloy was studied. The effect of the 1.6-μm-thick a-C:H:SiOx coating on the surface morphology, mechanical and tribological properties of VT-6 samples subjected to preliminary electron beam processing was also investigated. Parts of the disk pump were modified according to the proposed technology and pump was tested on the degree of red blood cell destruction. After modifying the surface of pump parts, the destruction of red blood cells did not occur during the 4-h experiment, unlike a similar pump without surface modification. It is shown that the physical properties of the surface are one of the most important factors affecting hemolysis in mechanical pumps to support stable heart function.

Effects of turbulization on the disc pump performance

Disc pumps are used for difficult pumping applications, such as, pumping of high suspension solids and abrasives, viscous fluids, air entrained and shear sensitive fluids. The pumping mechanism, based on the boundary layer effect and the viscous drag minimizes the contact between the pump and the fluid reducing the wear level; but the pumping mechanism itself makes its efficiency low in comparison with other pumps for similar applications. This research aims to increase the performance of this pump developing a new experimental study based on the turbulization of flow by the placement of turbulizers in the interdisc channel output. The variables involved are the angular velocity (ω) and the cross section shape of the turbulizers. Eight impellers were constructed and evaluated using as cross section shape of turbulizers: the triangular, circular, and square. The experimental results show that the creation of circulatory currents, according to the Kutta-Johkovsky theorem, contributes to the increase the efficiency and the head of the disc pump and the square cross section shape of the turbulizers offers the best results.

Optimization of the output device of a disk pump for high viscous fluid

In this paper the problem of designing an output device for dynamic pumps operating at a high fluid viscosity on the example of a disk pump was considered. The main objective of the study was to increase the pump efficiency by optimizing the geometry of the wet part of its volute. The dependences of the efficiency on the geometrical parameters of the output device estimated section were obtained. The results of the study are represented in a form of graphs and scalar field distributions.

Numerical study on the flow in balancing hole

In order to investigate the value of discharge coefficient of balancing hole Cd for wide range of axial flow velocity v in the hole and rotational speed u, series of CFD simulations are made. Some of the result agrees well with the existing experimental data, but the difference is about 20% in some cases with high Rev. Also, for wide area of Rev, the effect of rotating speed u becomes significant. So it is considered that the parameter v/u is a dominant indicator of Cd. Furthermore, for very low range of v/u, we found a rare flow situation with S-shaped streamlines. In this flow, pumping of disk is so strong and Cd may differ largely.

Development and research of hydraulic disk pump

The article is devoted to the development of the disk pump driven by a hydraulic motor at Bauman Moscow State Technical University Department of Hydraulics. The relevance of the dynamic pumps of this type has been described, and the necessity to investigate the mechanism of disk impellers operation using the tools of numerical hydrodynamic modeling, has been shown. The article presents the mathematical model used in computer simulation of the flow and the description of the testing bench. A comparison of numerical and full-scale experiments to confirm the adequacy of the mathematical model is introduced. A research showing the influence of some basic parameters of disk impellers on their characteristics (head, efficiency) has been performed. The figures of the scalar physical quantities distribution in the flow part of the pump and graphs of the pressure and efficiency dependences on the studied parameters are presented for a visual illustration of the results.

Flow-Rate–Pressure Characteristics of a Disk Blood Pump

An experimental model of a disk pump for pumping a liquid has been designed and fabricated. This model was tested on a special stand with the use of a 40% aqueous solution of glycerin whose hydrodynamical characteristics most closely correspond to those of blood. The results obtained lend credence to the view that an implantable blood pump can be developed on the basis of the disk pump.

Mathematical Model of Fluid Flow Between Rotating Nonplane Disks

A mathematical model of viscous fluid flow in the gap of a disk pump with nonplane disks has been developed. The characteristics of the pump — flow velocity, pressure drop, stress tensor, and the hydraulic coefficient of pump efficiency — have been calculated. A local pressure minimum in the pump has been detected, which leads to local ″choking″ of flow and to a decrease in the pressure characteristics and in the pump efficiency. The parameters causing the local ″choking″ of flow have been found, and the means of overcoming this phenomenon are indicated. An optimum inner radius of the disk at which maximum pressure drop and efficiency of the disk pump are achieved has been established, which made it possible to calculate the optimum parameters of the pump′s disk packet.

Heat Transfer Enhancements from Elastic Turbulence Using Sucrose-Based Polymer Solutions

The influences of elastic turbulence on convective heat transfer, within a C-shaped passage of a viscous disk pump, are experimentally determined using viscoelastic fluids and Boger fluids, which are constant-viscosity Newtonian solvents. Different concentrations of polyacrylamide in 65% sucrose solutions are used, along with solutions with 65% sucrose only, as different magnitudes of shear stress and strain rate are imposed upon the flowfield. Transition and development of elastic turbulence are characterized, along with convective heat transfer enhancements. The resulting increased levels of mixing, transport, and diffusion from elastic turbulence give convective heat transfer coefficient enhancements that are as large as 240%, relative to the Newtonian, Boger fluids at the same shear rate, rotation speed, flow passage height, and flow temperature. Variations of spectra of static temperature fluctuations and mean-square magnitudes of fluctuating static temperature provide evidence of increased flow irregularities and unsteadiness (relative to Boger solution flows), which result from elastic turbulence-induced polymer twisting, convolutions, and interactions. Such observed enhancements are shown to not be due to increased viscosity values alone, nor to centrifugal instabilities associated with streamline curvature, because Dean numbers are not large enough to allow development of the associated centrifugal-instability induced secondary flows.

Experimental evaluation of mechanical heart support system based on viscous friction disc pump

Aim. Experimental evaluation of the viscous friction disk pump efficiency, studying the relationship between inter-disk clearance and sizes of input and output ports and pump performance parameters.Materials and methods. To assess the characteristics and to optimize the disk friction pump design the pump model and experimental stand were created. Pump dimensions were set on the basis of medical and biological requirements for mechanical heart support systems and with due consideration of the experimental studies of our colleagues from Pennsylvania. Flow volume of the working fluid was measured by float rotameter Krohne VA-40 with measurement error of not more than 1%. The pressure values in the hydrodynamic circuit were measured using a monitor manufactured by Biosoft-M. Expansion device allowed changing the flow resistance of the system simulating the total peripheral resistance of the circulatory system.Results. Linear direct correlation between the pump performance and the pressure drop of liquid being created at the inlet and outlet of the pump was obtained. The required flow rate (5–7 l/min) and pressure (90–100 mmHg) were reached when the rotor speed was in the range of 2500–3000 rev/min. It has been shown that the increase of the inlet diameter to 15 mm has not resulted in a significant increase in the pump performance, and that the highest efficiency values can be obtained for the magnitude of inter-disk gap of 0.4–0.5 mm.Conclusion. Designed and manufactured experimental disc pump model for pumping fluid has showed the fundamental possibility to use this model as a system for mechanical support of the heart.

THE EXPERIMENTAL MODEL OF DISC-PUMP FOR MECHANICAL CIRCULATORY SUPPORT

The relevance of the use of circulatory support systems for the treatment of chronic heart failure (CHF) has increased over the recent years. Up to 20% of the patients from the waiting list for a donor heart die each year before they could get one. In our country, there is a huge need for mechanical heart support systems. However, the acquisition of foreign systems is associated with the excessive fi nancial costs. In addition, nowadays, there is no system that would meet all medical and technical requirements in full, and at the same time, would be of high safety for the patient. Therefore, research on the development of the systems of auxiliary circulation is highly relevant and is in demand in our country. One of the promising directions in this fi eld is disk pumps of viscous friction, which are based on the operation principle of Tesla disk pump. This article describes the creation and operation of the current model of the disk pump. The results of the bench tests confirmed that the expendable pressure characteristics of our disk pump are capable of providing the necessary parameters of blood circulation. The findings confi rm the perspective of the selected research area and provide the basis for further development and testing of this model of pump.