Experimental Hydraulic and Mechanical Characterisation of a Double-Flow Implantable Blood Pump

Abstract The considerable contribution of parasitic measurement effects in fluid flow machines of small performance classes remains a major challenge in the assessment of corresponding hydraulic characteristics such as hydraulic losses and efficiencies. However, a standardized experimental approach to accurately quantify such properties is of paramount importance for the design of rotary blood pumps with low hydraulic power and torque. This study proposes a novel test bench to accurately assess hydraulic and mechanical characteristics of pumps designed for a mechanical power input of up to 20,9W, a maximum rotational speed of 7000min−1 and a maximum torque of 10mNm. Key feature of the iteratively optimized test bench is a torque measuring shaft combined with ceramic bearings and seals that minimizes the friction torque to 0.66–0.69mNm. Preliminary measurements for a double-inflow, double-outflow circulatory support pump with maximum torque of 1.71mNm and hydraulic power of 0.15W, demonstrated both the feasibility of the hydraulic and mechanical design of the test bench and the reproducibility of the measured data. These results warrant the applicability of the presented test-bench for the investigation of typical cardiac assist systems as well as for all other hydraulic flow machines of the equivalent performance class.