Design of a Dual Propeller Micro-Pump in Conjunction With Flared TCPC for Cavopulmonary Assist in Fontan Patients

2017 ◽  
Author(s):  
Jakin Jagani ◽  
Alexandrina Untaroiu
Keyword(s):  
Blood Flow ◽  
Energy Loss ◽  
Flow Rate ◽  
Rotational Speed ◽  
Vena Cava ◽  
Pressure Rise ◽  
The Body ◽  
Axial Distance ◽  
Micro Pump ◽  
Flow Interference

A single ventricular physiology of the human heart caused by a dysfunctional right ventricle is usually treated with the three-stage Fontan operation. The outcome of this operation is an extra-cardiac total cavopulmonary connection (TCPC) which supplies the deoxygenated blood from the body to the lungs by directly connecting the inferior and superior vena cava (IVC and SVC) to the left and right pulmonary arteries (LPA and RPA). However, the situation is worsened due to non-physiologic flow conditions and pressure loss inside the cavopulmonary track, which ultimately calls for a heart transplantation. A modest pressure rise of 5–6 mm Hg will help to regain the normal physiology of the patient. In order to achieve this, a conceptual design of a dual propeller pump inside a flared TCPC is developed and studied. In order to provide a modest pressure rise, a blood pumping device was inserted inside the flared TCPC connection which consisted of two propellers, each placed in the SVC and the IVC and connected by a single shaft. The IVC and the SVC propellers were designed to rotate at the same rotational speed, having the same pressure rise but different blood inflow rate. The equal pressure rise across both the propellers was necessary at the design speed and flow rate to prevent any blood flow into the opposite vena cava. The TCPC-dual propeller conjunction was examined for the hydraulic performance and the flow pattern inside the TCPC using the 3D-CFD simulations on Ansys-CFX. The effect of axial distance between the two propellers on the blood flow interference and energy loss was also studied to select an optimal separation distance between them. The introduction of dual propeller pump inside the flared TCPC led to a pressure rise of 2–15 mm Hg at a total flow rate of 4.5 lpm (63% from IVC and 37% from SVC) with the rotational speed ranging from 6000–12000 rpm. It was seen that an axial separation of 70 mm between the two propellers provided the best performance in terms of flow interference and energy loss. A dual propeller pump assembled with an optimized TCPC could provide the required pressure rise for a particular age group of patients with univentricular Fontan physiology. The ability of dual micro-propeller pump to provide the required pressure rise will help to augment the cavopulmonary flow and hence help to regain the normal flow physiology as that witnessed by a human with biventricular circulation.

Studies on Downstream Stator With Rotor Re-Staggering and Forward Sweeping in a Subsonic Axial Compressor Stage

2011 ◽  
Author(s):  
P. V. Ramakrishna ◽  
M. Govardhan
Keyword(s):  
Flow Field ◽  
Computational Model ◽  
Flow Rate ◽  
Total Pressure ◽  
Axial Compressor ◽  
Pressure Rise ◽  
Axial Distance ◽  
Compressor Stage ◽  
Numerical Work ◽  
Stagger Angle

The present numerical work studies the flow field in subsonic axial compressor stator passages for: (a) preceding rotor sweep (b) preceding rotor re-staggering (three stagger angle changes: 0°, +3° and +5°); and (c) stator sweeping (two 20° forward sweep schemes). The following are the motives for the study: at the off-design conditions, compressor rotors are re-staggered to alleviate the stage mismatching by adjusting the rows to the operating flow incidence. Fundamental to this is the understanding of the effects of rotor re-staggering on the downstream component. Secondly, sweeping the rotor stages alters the axial distance between the successive rotor-stator stages and necessitates that the stator vanes must also be swept. To the best of the author’s knowledge, stator sweeping to suit such scenarios has not been reported. The computational model for the study utilizes well resolved hexahedral grids. A commercial CFD package ANSYS® CFX 11.0 was used with standard k-ω turbulence model for the simulations. CFD results were well validated with experiments. The following observations were made: (1) When the rotor passage is closed by re-staggering, with the same mass flow rate and the same stator passage area, stators were subjected to negative incidences. (2) Effect of stator sweeping on the upstream rotor flow field is insignificant. Comparison of total pressure rise carried by the downstream stators suggests that an appropriate redesign of stator is essential to match with the swept rotors. (3) While sweeping the stator is not recommended, axial sweeping is preferable over true sweeping when it is necessary.

The Response of a Centrifugal Pump to Fluctuating Rotational Speed

1995 ◽  
Vol 117 (3) ◽  
pp. 479-484 ◽  
Author(s):  
H. Tsukamoto ◽  
H. Yoneda ◽  
K. Sagara
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Dynamic Characteristics ◽  
Rotational Speed ◽  
Total Pressure ◽  
Flow Analysis ◽  
Pressure Rise ◽  
Singularity Method ◽  
Measured Flow ◽  
Unsteady Characteristics

A theoretical and experimental study has been made on the dynamic characteristics of a centrifugal pump subject to sinusoidal changes in rotational speed. Time-dependent rotational speed, flow-rate, and total pressure rise are measured for a variety of amplitude and frequency of the fluctuating rotational speed. Measured flow-rate as well as total pressure rise is compared with the quasi-steady ones. Unsteady flow analysis is made for a two-dimensional circular cascade by use of the singularity method. The calculated frequency characteristics are compared with the corresponding experimental ones. The deviation of unsteady characteristics from quasi-steady ones is evident, and the numerical results agree qualitatively with the measured ones. It was found that with the increased frequency of rotational speed fluctuations the dynamic characteristics deviate remarkably from quasi-steady ones. Moreover, a criterion for the assumption of quasi-steady change is presented.

Deviations Due to Non-Newtonian Influences Within a Miniature Viscous Disk Pump

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Phil Ligrani ◽  
Hui Jiang ◽  
Benjamin Lund ◽  
Jae Sik Jin
Keyword(s):  
Newtonian Fluid ◽  
Flow Rate ◽  
Rotational Speed ◽  
Stokes Equations ◽  
Sucrose Concentration ◽  
Pure Water ◽  
Pressure Rise ◽  
Volumetric Flow Rate ◽  
Newtonian Flow ◽  
Newtonian Behavior

A miniature viscous disk pump (VDP) is utilized to characterize and quantify non-Newtonian fluid deviations due to non-Newtonian influences relative to Newtonian flow behavior. Such deviations from Newtonian behavior are induced by adding different concentrations of sucrose to purified water, with increasing non-Newtonian characteristics as sucrose concentration increases from 0% (pure water) to 10% by mass. The VDP consists of a 10.16 mm diameter disk that rotates above a C-shaped channel with inner and outer radii of 1.19 mm, and 2.38 mm, respectively, and a channel depth of 200 μm. Fluid inlet and outlet ports are located at the ends of the C-shaped channel. Within the present study, experimental data are given for rotational speeds of 1200–2500 rpm, fluid viscosities of 0.001–0.00134 Pa s, pressure rises of 0–220 Pa, and flow rates up to approximately 0.00000005 m3/s. The theory of Flumerfelt is modified and adapted for application to the present VDP environment. Included is a new development of expressions for dimensionless volumetric flow rate, and normalized local circumferential velocity for Newtonian and non-Newtonian fluid flows. To quantify deviations due to the magnitude non-Newtonian flow influences, a new pressure rise parameter is employed, which represents the dimensional pressure rise change at a particular flow rate and sucrose concentration, as the flow changes from Newtonian to non-Newtonian behavior. For 5% and 10% sucrose solutions at rotational speeds of 1200–2500 rpm, this parameter increases as the disk dimensional rotational speed increases and as the volumetric flow rate decreases. Associated magnitudes of the pressure difference parameter show that the fluid with the larger sucrose concentration (by mass) produces significantly larger differences between Newtonian and non-Newtonian fluid flow, for each value of dimensional volumetric flow rate. For each disc rotational speed, compared to Newtonian data, dimensional pressure rise variations with dimensional volumetric flow rate, which are associated with the non-Newtonian data, are generally lower when compared at a particular volumetric flow rate. Agreement with analytic results, for any given flow rate, rotational speed, and flow passage height, validates the shear stress model employed to represent non-Newtonian behavior, as well as the analytic equations and tools (based upon the Navier–Stokes equations) which are employed to predict measured behavior over the investigated range of experimental conditions.

Miniature Single-Disk Viscous Pump (Single-DVP), Performance Characterization

2005 ◽  
Vol 128 (3) ◽  
pp. 602-610 ◽  
Author(s):  
Danny Blanchard ◽  
Phil Ligrani ◽  
Bruce Gale
Keyword(s):  
Flow Rate ◽  
Rotational Speed ◽  
Pressure Rise ◽  
Volumetric Flow Rate ◽  
Outer Radius ◽  
Fluid Viscosity ◽  
Pump Chamber ◽  
Inner Radius ◽  
Viscous Pump ◽  
Single Disk

The development and testing of a rotating single-disk viscous pump are described. This pump consists of a 10.16mm diameter spinning disk, and a pump chamber, which are separated by a small gap that forms the fluid passage. The walls of the pump chamber form a C-shaped channel with an inner radius of 1.19mm, an outer radius of 2.38mm, and a depth of 40, 73, 117, or 246μm. Fluid inlet and outlet ports are located at the ends of the C-shaped channel. Experimental flow rate and pressure rise data are obtained for rotational speeds from 100to5000rpm, fluid chamber heights from 40to246μm, flow rates from 0to4.75ml∕min, pressure rises from 0to31.1kPa, and fluid viscosities from 1to62mPas. An analytical expression for the net flow rate and pressure rise, as dependent on the fluid chamber geometry, disk rotational speed, and fluid viscosity, is derived and found to agree with the experimental data. The flow rate and pressure rise of the pump vary nearly linearly with rotational speed. The volumetric flow rate does not change significantly with changes in fluid viscosity for the same rotational speed and pumping circuit. Advantages of the disk pumps include simplicity, ease of manufacture, ability to produce continuous flow with a flow rate that does not vary significantly in time, and ability to pump biological samples without significant alteration or destruction of cells, protein suspension, or other delicate matter.

Experimental and Numerical Studies of Pump Transient Characteristics During Stopping Period

2014 ◽  
Author(s):  
Peng Wu ◽  
Dazhuan Wu ◽  
Leqin Wang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Rotational Speed ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Hydrodynamic Characteristics ◽  
Rotational Inertia ◽  
Operating Characteristics ◽  
Transient Characteristics ◽  
Numerical Studies

Experimental and numerical studies were carried out to study the transient characteristics of the centrifugal pump during stopping periods. Different stopping schemes were realized by changing the rotational inertia of the flywheels. Transient revolution rotational speed, flow-rate, total pressure rise and torque were measured under different rotational inertia. Experimental results of different operating conditions were compared, and transient hydrodynamics performances of the centrifugal pump model were analyzed. In order to provide boundary conditions for numerical simulations, the revolution curves of the flow-rate and the rotational speed were polynomial fitted. Three dimensional unsteady incompressible viscous flows during stopping periods were studied by using DES model in FLUENT. Results show that the hydrodynamic characteristics of numeric and experiment agree well. The transient effect is not so evident, and the quasi-steady assumption is acceptable during most part of coastdown process. The pump characteristics are further explained by analyzing the relative velocity on the middle stream surfaces. At the end of the stopping period, the transient vortex evolution between blades is the main reason why the transient curves deviates the steady curve. The studies can help understand the operating characteristics of centrifugal pump when power failure accident occurs.

EFFECT OF BODY MASS INDEX ON PEAK EXPIRATORY FLOW RATE

2019 ◽  
Vol 3 (9) ◽  
Author(s):  
K. Subramanyam ◽  
Dr. P. Subhash Babu
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Peak Expiratory Flow ◽  
Flow Rate ◽  
Peak Expiratory Flow Rate ◽  
Normal Weight ◽  
The Body ◽  
Health Care Centre ◽  
Expiratory Flow ◽  
Group B

Obesity has become one of the major health issues in India. WHO defines obesity as “A condition with excessive fat accumulation in the body to the extent that the health and wellbeing are adversely affected”. Obesity results from a complex interaction of genetic, behavioral, environmental and socioeconomic factors causing an imbalance in energy production and expenditure. Peak expiratory flow rate is the maximum rate of airflow that can be generated during forced expiratory manoeuvre starting from total lung capacity. The simplicity of the method is its main advantage. It is measured by using a standard Wright Peak Flow Meter or mini Wright Meter. The aim of the study is to see the effect of body mass index on Peak Expiratory Flow Rate values in young adults. The place of a study was done tertiary health care centre, in India for the period of 6 months. Study was performed on 80 subjects age group 20 -30 years, categorised as normal weight BMI =18.5 -24.99 kg/m2 and overweight BMI =25-29.99 kg/m2. There were 40 normal weight BMI (Group A) and 40 over weight BMI (Group B). BMI affects PEFR. Increase in BMI decreases PEFR. Early identification of risk individuals prior to the onset of disease is imperative in our developing country. Keywords: BMI, PEFR.

COMPARISON OF ANTIHYPERTENSIVE EFFECT OF MOXONIDINE VERSUS CLONIDINE IN RENAL FAILURE PATIENTS.

2018 ◽  
Vol 6 (9) ◽  
Author(s):  
DR.MATHEW GEORGE ◽  
DR.LINCY JOSEPH ◽  
MRS.DEEPTHI MATHEW ◽  
ALISHA MARIA SHAJI ◽  
BIJI JOSEPH ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Renal Failure ◽  
Blood Flow ◽  
Blood Vessel ◽  
Blood Vessels ◽  
High Blood Pressure ◽  
Antihypertensive Effect ◽  
The Body ◽  
Ability To Work ◽  
Blood Flows

Blood pressure is the force of blood pushing against blood vessel walls as the heart pumps out blood, and high blood pressure, also called hypertension, is an increase in the amount of force that blood places on blood vessels as it moves through the body. Factors that can increase this force include higher blood volume due to extra fluid in the blood and blood vessels that are narrow, stiff, or clogged(1). High blood pressure can damage blood vessels in the kidneys, reducing their ability to work properly. When the force of blood flow is high, blood vessels stretch so blood flows more easily. Eventually, this stretching scars and weakens blood vessels throughout the body, including those in the kidneys.

Effekt of blood flow shutdown on the vein damage when exposed to HIFU

2017 ◽  
pp. 46-50
Author(s):  
Н.Н. Петрищев ◽  
Д.Ю. Семенов ◽  
А.Ю. Цибин ◽  
Г.Ю. Юкина ◽  
А.Е. Беркович ◽  
...  
Keyword(s):  
Blood Flow ◽  
Structural Changes ◽  
Focused Ultrasound ◽  
Vena Cava ◽  
Posterior Wall ◽  
High Intensity Focused Ultrasound ◽  
Vein Wall ◽  
Ultrasound Exposure ◽  
Isolated Segment ◽  
The Impact

The purpose. In the study we investigated the impact of the partial blood flow shutdown on structural changes in the rabbit vena cava posterior wall after exposure to high-intensity focused ultrasound (HIFU). Methods. Ultrasound Exposure: frequency of 1.65 MHz, the ultrasound intensity in the focus of 13.6 kW/cm, the area of the focal spot 1 mm, continuous ultrasound, exposure for 3 seconds. Results. Immediately after HIFU exposure all layers of the vein wall showed characteristic signs of thermal damage. A week after exposure structural changes in the intima, media and adventitia was minimal in the part of vessel with preserved blood flow, and after 4 weeks the changes were not revealed. A week after HIFU exposure partial endothelium destruction, destruction of myocytes, disorganization and consolidation of collagen fibers of the adventitia were observed in an isolated segment of the vessel, and in 4 weeks endothelium restored and signs of damage in media and adventitia persisted, but were less obvious than in a week after exposure. Conclusion. The shutdown of blood flow after exposure to HIFU promotes persistent changes in the vein wall. Vein compression appears to be necessary for the obliteration of the vessel, when using HIFU-technology.

scholarly journals Calculating the optimal hematocrit under the constraint of constant cardiac power

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Michal Sitina ◽  
Heiko Stark ◽  
Stefan Schuster
Keyword(s):  
Blood Flow ◽  
High Performance ◽  
Animal Species ◽  
Normal Values ◽  
Mechanical Load ◽  
The Body ◽  
Trade Off ◽  
Cardiac Power ◽  
Optimal Value ◽  
Good Agreement

AbstractIn humans and higher animals, a trade-off between sufficiently high erythrocyte concentrations to bind oxygen and sufficiently low blood viscosity to allow rapid blood flow has been achieved during evolution. Optimal hematocrit theory has been successful in predicting hematocrit (HCT) values of about 0.3–0.5, in very good agreement with the normal values observed for humans and many animal species. However, according to those calculations, the optimal value should be independent of the mechanical load of the body. This is in contradiction to the exertional increase in HCT observed in some animals called natural blood dopers and to the illegal practice of blood boosting in high-performance sports. Here, we present a novel calculation to predict the optimal HCT value under the constraint of constant cardiac power and compare it to the optimal value obtained for constant driving pressure. We show that the optimal HCT under constant power ranges from 0.5 to 0.7, in agreement with observed values in natural blood dopers at exertion. We use this result to explain the tendency to better exertional performance at an increased HCT.

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