Gap velocity measurements of a blood pump model.
This paper presents the velocity measurements in the gap between the impeller and the pump casing of a 5:1 enlarged centrifugal blood pump model at operating condition. Both the radial and tangential velocity at the gap were measured. It was found that there was no cross flow in both the radial and tangential velocity distributions at the seven radial locations. This implies that the 0.2 mm gap in the prototype should be the optimal clearance of the pump. The vector plot of the resultant velocity showed that the double volute design of the pump, especially the splitter plate that started at theta; = 180 degrees, has created a washout mechanism in the clearance gap; that is, a sector of flow ranging from theta; = 100 degrees to theta; = 190 degrees has directed strongly toward the eye while the rest of the flow in the gap is in a tangential direction. It is important that the blood should flow out of the gap through the eye instead of continuing to circulate in the clearance gap. This explains why the pump has minimum hemolysis and thrombus formation and is able to function with nominal efficiency as compared to other centrifugal pumps.
School of Mechanical and Production Engineering Nanyang Technological University, Singapore.
Leok Poh
LP
Chua
Kang Shiu
KS
Ong
Ching Man Simon
CM
Yu
Weng Kong
WK
Chan
Yew Wah
YW
Wong
D001696:Biomechanical Phenomena; D001783:Blood Flow Velocity / Q000502:physiology*; D004867:Equipment Design; D006353:Heart-Assist Devices / Q000592:standards*; D006461:Hemolysis; D018056:Hemorheology / Q000295:instrumentation*; D008433:Mathematics; D013927:Thrombosis / Q000517:prevention & control