Second Heart Report · 2018. 11. 8. · enmodes GmbH engineering modeling design Second Heart Report July 12, 2018 Dr. Fiete Böhning Head of Engineering Services [email protected]

enmodes GmbH

engineeringmodeling

design

Second Heart ReportJuly 12, 2018

Dr. Fiete Böhning

Head of Engineering Services

[email protected]

+49 (0)241 41251073

+49 (0)176 78013798

enmodes GmbH

Wilhelmstraße 38

52070 Aachen

Germany

www.enmodes.de – engineering, modeling, design

Contact details

1

Overview of the device

CAD geometry provided by Second HeartImpeller diameter: 13.5 & 14.5 mmOpen stent (outer) diameter: 22.86 mm

2

Volume extraction

Tube around the deviceTube diameter: 22.86 mm

Extracted fluid volume for flow simulations

3

Boundary conditions

• Flow Inlet (L/min):3.5, 4.5 & 5.5

• Impeller Speeds (rpm):7500, 10500 & 15000

• Non-Newtonian Blood Model• Full 3D simulation

Inlet

Outlet

4

Analysis Results

∆P = Pressure outlet – Pressure inlet

RPM 15000; average increase in pressure head ≈ 31%

RPM 10500; average increase in pressure head ≈ 40%

RPM 7500; ; average increase in pressure head ≈ 66%

Impeller 13.5Impeller 14.5

5

General observations

Large back flow whirls above the impeller blades → reduces the efficiency

6

General observations

Continuous back flow along the impeller shaft → reduces the efficiency

7

General observations (Impeller – 14.5 mm)

High velocity and low pressures around the blade tip → potentially unnecessary high shear stresses

VelocityPressure

8

Comparison of Impellers

Impeller 14.5 mmImpeller 13.5 mm

9

Comparison of Impellers

Impeller 14.5 mmImpeller 13.5 mm

10

Impeller – 14.5 mm

11

Flow simulation – Flow 3.5 L/min at 10500 rpm

Plane 2

12

Flow simulation – Flow 4.5 L/min at 10500 rpm

Plane 2

13

Flow simulation – Flow 5.5 L/min at 10500 rpm

Plane 2

14

Velocity and Streamlines – Flow 3.5 L/min at 7500 rpm

15

Velocity and Streamlines – Flow 4.5 L/min at 7500 rpm

16

Velocity and Streamlines – Flow 5.5 L/min at 7500 rpm

17

Velocity and Streamlines – Flow 3.5 L/min at 10500 rpm

18

Velocity and Streamlines – Flow 4.5 L/min at 10500 rpm

19

Velocity and Streamlines – Flow 5.5 L/min at 10500 rpm

20

Velocity and Streamlines – Flow 3.5 L/min at 15000 rpm

21

Velocity and Streamlines – Flow 4.5 L/min at 15000 rpm

22

Velocity and Streamlines – Flow 5.5 L/min at 15000 rpm

23

Comparison of Flow: 3.5, 4.5 & 5.5 L/min at 10500 rpm

Back flow whirls are almost the same for all flow rate for a constant impeller speed.

24

Comparison of Speed: 7500, 10500 & 15000 rpm at 4.5 L/min

Back flow whirls increases with increase in impeller speed for a constant flow rate.

25

Impeller – 13.5 mm

next slides are as sent in the previous report

26

General observations (Impeller – 13.5 mm)

High velocity and low pressures around the blade tip → potentially unnecessary high shear stresses

VelocityPressure

27

Flow simulation – Flow 3.5 L/min at 10500 rpm

Plane 2

28

Flow simulation – Flow 4.5 L/min at 10500 rpm

Plane 2

29

Flow simulation – Flow 5.5 L/min at 10500 rpm

Plane 2

30

Velocity and Streamlines – Flow 3.5 L/min at 7500 rpm

31

Velocity and Streamlines – Flow 4.5 L/min at 7500 rpm

32

Velocity and Streamlines – Flow 5.5 L/min at 7500 rpm

33

Velocity and Streamlines – Flow 3.5 L/min at 10500 rpm

34

Velocity and Streamlines – Flow 4.5 L/min at 10500 rpm

35

Velocity and Streamlines – Flow 5.5 L/min at 10500 rpm

36

Velocity and Streamlines – Flow 3.5 L/min at 15000 rpm

37

Velocity and Streamlines – Flow 4.5 L/min at 15000 rpm

38

Velocity and Streamlines – Flow 5.5 L/min at 15000 rpm

39

Comparison of Flow: 3.5, 4.5 & 5.5 L/min at 10500 rpm

Back flow whirls decrease with increase in flow rate for a constant impeller speed.

40

Comparison of Speed: 7500, 10500 & 15000 rpm at 4.5 L/min

Back flow whirls increases with increase in impeller speed for a constant flow rate.

41

Summary

The current study was conducted for an impeller with blade diameters of 13.5 & 14.5 mm, in a tubewith the same outer diameter as that of the open stent, i.e. 22.86 mm. Simulations were carried out forconstant flow conditions.

Comparison of the two impellers:

• In general, the pressure head developed by the bigger 14.5 mm impeller is better than that of the13.5 mm impeller.

• The local hydraulic behaviour of the impellers are similar.

General observations (presented in earlier report):

• The current design of the Second Heart implantable device results in large back flows around the impeller reducing the efficiency ofthe device.

• It also has a potential for unnecessary high shear stresses around the impeller blades.

• The current analysis also does not provide any indicators for the device effectiveness in human anatomy with respect to pathologicalconditions, pulsatile flow conditions, device placement, etc.

• Further analysis & design optimization are needed to improve the device performance and its blood compatibility.