Computational flow study of the continuous flow ventricular assist device,prototype number 3 blood pump

A computational fluid dynamics study of blood flow in the continuous flow v entricular assist device, Prototype No. 3 (CFVAD3), which consists of a 4 b lade shrouded impeller fully supported in magnetic bearings, was performed. This study focused on the regions within the pump where return flow occurs to the pump inlet, and where potentially damaging shear stresses and flow stagnation might occur: the impeller blade passages and the narrow gap clea rance regions between the impeller-rotor and pump housing. Two separate geo metry models define the spacing between the pump housing and the impeller's hub and shroud, and a third geometry model defines the pump's impeller and curved blades. The flow fields in these regions were calculated for variou s operating conditions of the pump. Pump performance curves were calculated , which compare well with experimentally obtained data. For all pump operat ing conditions, the flow rates within the gap regions were predicted to be toward the inlet of the pump, thus recirculating a portion of the impeller flow. Two smaller gap clearance regions were numerically examined to reduce the recirculation and to improve pump efficiency. The computational and ge ometry models will be used in future studies of a smaller pump to determine increased pump efficiency and the risk of hemolysis due to shear stress, a nd to insure the washing of blood through the clearance regions to prevent thrombosis.