centrifugal blood pump design

8/8/2019 Centrifugal Blood Pump Design

1/25

Centrifugal Blood PumpCentrifugal Blood Pump

Impeller Test & DesignImpeller Test & Design

Ryan KlatteRyan KlatteCCF AdvisorCCF Advisor-- Dr. William SmithDr. William Smith

Univ. of Akron AdvisorUniv. of Akron Advisor--Dr. StanDr. Stan RittgersRittgers

Cleveland Clinic FoundationCleveland Clinic Foundation

National Science FoundationNational Science Foundation


2/25

Background:Background:

Statistics:Statistics:According to the National Center for HealthAccording to the National Center for Health

Statistics, in 1996, 21 million Americans wereStatistics, in 1996, 21 million Americans were

afflicted with heart disease.afflicted with heart disease. In 1997, 726,974 Americans were killed by heartIn 1997, 726,974 Americans were killed by heart

disease, making it the number one cause of deathdisease, making it the number one cause of death

in the U.S.in the U.S.


3/25

(Background continued)(Background continued)

Although many treatments are available forAlthough many treatments are available forheart disease victims, many require heartheart disease victims, many require heart

transplants to survive, let alone functiontransplants to survive, let alone function

normally.normally. Drawbacks of heart transplants:Drawbacks of heart transplants:

Difficulty of finding donor organs.Difficulty of finding donor organs.

Possibility of rejection.Possibility of rejection.


4/25


Solutions:Solutions: Implant an artificial heartImplant an artificial heart

Genetic engineering??Genetic engineering??

Efforts are wide spread to develop aEfforts are wide spread to develop aVentricular Assist Device (VAD) or a TotalVentricular Assist Device (VAD) or a Total

Artificial Heart (TAH).Artificial Heart (TAH).


5/25


Cleveland Clinic Foundation:Cleveland Clinic Foundation:

Here at Lerner Institute, the Cardiac Assist and ReplacementHere at Lerner Institute, the Cardiac Assist and Replacement

Group (CARG) is attempting to develop a Left VAD (LVAD) inGroup (CARG) is attempting to develop a Left VAD (LVAD) in

accord with the Whitaker Foundation Grant.accord with the Whitaker Foundation Grant.

The device used will be a centrifugal pump.The device used will be a centrifugal pump.


6/25


Centrifugal Pump characteristics:Centrifugal Pump characteristics:

Continuous flow, nonContinuous flow, non--pulsatilepulsatile..

Simple device:Simple device:

HousingHousing Impeller (sole moving part)Impeller (sole moving part)

MotorMotor

Relatively simple design.Relatively simple design.


7/25


Unfortunately, little information is available about theUnfortunately, little information is available about the

effect of impeller geometry on overall pumpeffect of impeller geometry on overall pump

performance.performance.

Most centrifugal pumps are designed by trialMost centrifugal pumps are designed by trial--andand--

error methods.error methods.

It would be highly beneficial to have a tool that couldIt would be highly beneficial to have a tool that could

accurately predict pump performance for a givenaccurately predict pump performance for a given

design.design.


8/25


9/25

TheoryTheory

2224 rn

p

=

DimensionlessDimensionlessparameters used:parameters used: Pressure Coefficient:Pressure Coefficient:

Flow Coefficient:

nr22Re =

3538 nr

P

=

4/3H

QnNs =

Specific Speed:Specific Speed:

ReynoldsReynolds Number:Number:

Power Coefficient:Power Coefficient:

Flow Coefficient:

nr

Q3

2=


10/25

(Theory continued):

EulerEuler Equation:Equation:

Velocity triangles:

g

cucuH uuth1122

=

Velocity triangles:


11/25

Specific Aims:Specific Aims: Pump MappingPump Mapping: This involves recording the necessary: This involves recording the necessary

data for each respective impeller/housingdata for each respective impeller/housing

configuration. There are 17 configurations currentlyconfiguration. There are 17 configurations currently

tested. More will be done as time permits.tested. More will be done as time permits.

Modify ProgramModify Program: The empirical data recorded will be: The empirical data recorded will beused to modify an existing program to accuratelyused to modify an existing program to accurately

predict pump performance based upon impellerpredict pump performance based upon impeller

geometry, fluid properties, and rotational speed (togeometry, fluid properties, and rotational speed (tobe done at UA).be done at UA).

Impeller DesignImpeller Design: The design program could be used: The design program could be used

to design improved impellers (to be done at UA)to design improved impellers (to be done at UA)


12/25

(Specific aims continued)(Specific aims continued)

Implications of this research:Implications of this research:

The data recorded will be useful for futureThe data recorded will be useful for future

research.research.

New impellers can be designed faster andNew impellers can be designed faster and

cheaper.cheaper.

Blood pumps could be easily modified to meet anBlood pumps could be easily modified to meet an

individual patients needs.individual patients needs.


13/25

Update:Update: Before I could begin actual testing, I had to performBefore I could begin actual testing, I had to perform

several tasks:several tasks:

Design a dynamometer that would accommodate the newDesign a dynamometer that would accommodate the new

torque sensor.torque sensor.


14/25

Update (continued)Update (continued)

Build the actual test loop. The old test loop leaked.Build the actual test loop. The old test loop leaked.


15/25


Redesign the adapter and spacer parts that attached theRedesign the adapter and spacer parts that attached the

pump housing to the magnetic coupling.pump housing to the magnetic coupling.


16/25


Initial testing revealed that the housings intended for testingInitial testing revealed that the housings intended for testing

were poor. Because of this, I designed a new housing.were poor. Because of this, I designed a new housing.


17/25


Final incarnation of dynamometer & pumpFinal incarnation of dynamometer & pump


18/25

Testing:Testing: The respective impeller/housing configurations will beThe respective impeller/housing configurations will be

run in a test loop.run in a test loop.

The control fluid is a water/glycerin mixture withThe control fluid is a water/glycerin mixture with

viscosity equivalent to blood viscosity.viscosity equivalent to blood viscosity.

The control fluid will be held at constantThe control fluid will be held at constant

temperature.temperature.

The control fluid will be sterilized.The control fluid will be sterilized.


19/25

(Testing continued):(Testing continued):

Data acquisitionData acquisition

devices:devices:

Pressure tapsPressure taps

Torque transducerTorque transducer FlowFlow--metermeter

Motor controllerMotor controller

drive

Data Collected:Data Collected:

Inlet/Outlet PressureInlet/Outlet Pressure

Input TorqueInput Torque

FlowFlow--raterate Rotational SpeedRotational Speed

drive


20/25

(Testing continued):(Testing continued):

Each impeller/housing configuration will beEach impeller/housing configuration will be

tested at 3 different gaps, with 3 rotationaltested at 3 different gaps, with 3 rotational

speeds per gap, and 15 differentspeeds per gap, and 15 different flowratesflowrates

per rotational speed.per rotational speed. This is a total of 135 data points perThis is a total of 135 data points per

configuration.configuration.


21/25

Analysis:Analysis:

The data will be organized into several differentThe data will be organized into several different

plots, using dimensionless parameters.plots, using dimensionless parameters.

Dimensionless parameters are useful because:Dimensionless parameters are useful because:

Easy to compare different configurations.Easy to compare different configurations.

Allow several variables in a single plot.Allow several variables in a single plot.

Provide a method to compare similarity ofProvide a method to compare similarity of

different pumps.different pumps.


22/25

(Analysis continued):(Analysis continued):

Example: Efficiency vs. Specific SpeedExample: Efficiency vs. Specific Speed

Efficiency vs. Specific Speed

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Ns [-]

[-

]

2000 RPM

2500 RPM

3000 RPM

3500 RPM

4000 RPM


23/25


Example: Power Coefficient vs. Flow CoefficientExample: Power Coefficient vs. Flow Coefficient

Nondimensional Power vs. Nondimensional Flow

0.00000

0.02000

0.04000

0.06000

0.08000

0.10000

0.12000

0.14000

0.16000

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14

[-]

[-

]

2000 RPM

2500 RPM

3000 RPM

3500 RPM

4000 RPM


24/25


Example: Pressure Coefficient vs. Flow CoefficientExample: Pressure Coefficient vs. Flow Coefficient

Nondimensional Pressure vs. Nondimensional Flow

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14

[-]

[-

]

2000 RPM

2500 RPM

3000 RPM

3500 RPM

4000 RPM


25/25

Questions?Questions?

centrifugal blood pump design

Documents