Second Heart Report. July 12, engineering modeling design. Contact details. enmodes GmbH

Transcription

1 enmodes GmbH engineering modeling design Second Heart Report July 12, 2018 Contact details Dr. Fiete Böhning Head of Engineering Services +49 (0) (0) enmodes GmbH Wilhelmstraße Aachen Germany engineering, modeling, design

2 Overview of the device CAD geometry provided by Second Heart Impeller diameter: 13.5 & 14.5 mm Open stent (outer) diameter: mm 1

3 Volume extraction Tube around the device Tube diameter: mm Extracted fluid volume for flow simulations 2

4 Boundary conditions Flow Inlet (L/min): 3.5, 4.5 & 5.5 Impeller Speeds (rpm): 7500, & Non-Newtonian Blood Model Full 3D simulation Inlet Outlet 3

5 Analysis Results Impeller 13.5 Impeller 14.5 RPM 15000; average increase in pressure head 31% RPM 10500; average increase in pressure head 40% RPM 7500; ; average increase in pressure head 66% P = Pressure outlet Pressure inlet 4

6 General observations Large back flow whirls above the impeller blades reduces the efficiency 5

7 General observations Continuous back flow along the impeller shaft reduces the efficiency 6

8 General observations (Impeller 14.5 mm) High velocity and low pressures around the blade tip potentially unnecessary high shear stresses Pressure Velocity 7

9 Comparison of Impellers Impeller 13.5 mm Impeller 14.5 mm 8

10 Comparison of Impellers Impeller 13.5 mm Impeller 14.5 mm 9

11 Impeller 14.5 mm 10

12 Flow simulation Flow 3.5 L/min at rpm Plane 2 11

13 Flow simulation Flow 4.5 L/min at rpm Plane 2 12

14 Flow simulation Flow 5.5 L/min at rpm Plane 2 13

15 Velocity and Streamlines Flow 3.5 L/min at 7500 rpm 14

16 Velocity and Streamlines Flow 4.5 L/min at 7500 rpm 15

17 Velocity and Streamlines Flow 5.5 L/min at 7500 rpm 16

18 Velocity and Streamlines Flow 3.5 L/min at rpm 17

19 Velocity and Streamlines Flow 4.5 L/min at rpm 18

20 Velocity and Streamlines Flow 5.5 L/min at rpm 19

21 Velocity and Streamlines Flow 3.5 L/min at rpm 20

22 Velocity and Streamlines Flow 4.5 L/min at rpm 21

23 Velocity and Streamlines Flow 5.5 L/min at rpm 22

24 Comparison of Flow: 3.5, 4.5 & 5.5 L/min at rpm Back flow whirls are almost the same for all flow rate for a constant impeller speed. 23

25 Comparison of Speed: 7500, & rpm at 4.5 L/min Back flow whirls increases with increase in impeller speed for a constant flow rate. 24

26 Impeller 13.5 mm next slides are as sent in the previous report 25

27 General observations (Impeller 13.5 mm) High velocity and low pressures around the blade tip potentially unnecessary high shear stresses Pressure Velocity 26

28 Flow simulation Flow 3.5 L/min at rpm Plane 2 27

29 Flow simulation Flow 4.5 L/min at rpm Plane 2 28

30 Flow simulation Flow 5.5 L/min at rpm Plane 2 29

31 Velocity and Streamlines Flow 3.5 L/min at 7500 rpm 30

32 Velocity and Streamlines Flow 4.5 L/min at 7500 rpm 31

33 Velocity and Streamlines Flow 5.5 L/min at 7500 rpm 32

34 Velocity and Streamlines Flow 3.5 L/min at rpm 33

35 Velocity and Streamlines Flow 4.5 L/min at rpm 34

36 Velocity and Streamlines Flow 5.5 L/min at rpm 35

37 Velocity and Streamlines Flow 3.5 L/min at rpm 36

38 Velocity and Streamlines Flow 4.5 L/min at rpm 37

39 Velocity and Streamlines Flow 5.5 L/min at rpm 38

40 Comparison of Flow: 3.5, 4.5 & 5.5 L/min at rpm Back flow whirls decrease with increase in flow rate for a constant impeller speed. 39

41 Comparison of Speed: 7500, & rpm at 4.5 L/min Back flow whirls increases with increase in impeller speed for a constant flow rate. 40

42 Summary The current study was conducted for an impeller with blade diameters of 13.5 & 14.5 mm, in a tube with the same outer diameter as that of the open stent, i.e mm. Simulations were carried out for constant 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 the 13.5 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 of the 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 pathological conditions, pulsatile flow conditions, device placement, etc. Further analysis & design optimization are needed to improve the device performance and its blood compatibility. 41