Objective： Hemolysis in blood pumps has been measured by various in vitro test methods, in which normalized index of hemolysis （NIH） was established. As NIH is complicated and difficult to calculate, erythrocyte fr...Objective： Hemolysis in blood pumps has been measured by various in vitro test methods, in which normalized index of hemolysis （NIH） was established. As NIH is complicated and difficult to calculate, erythrocyte fragment count is proposed in the present study to predict hemolysis in roller pumps. Methods： Five paired in vitro tests were conducted using the POLYSTAN pediatric pump（group A） and COBE pump（ group B）. Ten whole blood samples （400 ml ） were circled in the roller pump for 16 h. Erythrocyte fragments count and plasma-free hemoglobin （FHb） were measured before pumping and every two hours through circulation after four-hour-pumping. The morphological changes of erythrocyte were observed by scanning electron microscope. Results： The two groups＇ EFC and FHb levels were increased linearly during a long duration of pumping and linear regression of erythrocyte fragments count and plasma-free hemoglobin were correlated. Conclusion： Erythrocyte fragments count could be used as an index in evaluating the in vitro hemolytic properties of blood pumps.展开更多
This study presents a novel roller piston pump,in which a cam guide-roller type rolling support is adopted to replace the sliding pair support of the swash plate-slipper pair to achieve the oil suction and discharge o...This study presents a novel roller piston pump,in which a cam guide-roller type rolling support is adopted to replace the sliding pair support of the swash plate-slipper pair to achieve the oil suction and discharge of the piston cavity.In addition,the shaft distribution is used to replace the original valve plate distribution and the driving shaft is used as the distribution shaft to remove the valve plate structure,which greatly simplifies the design of the axial piston pump.Such a configuration largely reduces the number of sliding friction pairs of the pump,and avoids the influence of the sliding friction pair on it under high-speed and variable-speed conditions.Firstly,mathematical models of the mechanical and volumetric efficiencies of the roller pump are deduced respectively through force analysis and the compressibility equation.Based on the numerical simulation of MATLAB and AMESim,the effects of load pressure and rotational speed on mechanical and volumetric efficiencies are studied respectively,and it is verified that the roller pump has no structural flow pulsation.The prototype pump is then designed and built,along with a special test rig.The outlet pressure,outlet flow,and torque of the pump under different load pressures and rotational speeds are measured,and the mechanical and volumetric efficiencies of the prototype pump under various load pressures and rotational speeds are obtained.The experimental results are in good agreement with the simulated analysis.When the load pressure is 8 MPa and the speed is 5000 r/min,the mechanical and the volumetric efficiencies are 85.5% and 96.8%,respectively.When the speed is increased to 10000 r/min,the mechanical and the volumetric efficiencies are 66.7% and 95.6%,respectively.The experimental results show that the proposed roller piston pump has excellent efficiency under wide-speed and high-speed conditions and can be a potential solution as a fuel pump in aerospace fuel systems.展开更多
文摘Objective： Hemolysis in blood pumps has been measured by various in vitro test methods, in which normalized index of hemolysis （NIH） was established. As NIH is complicated and difficult to calculate, erythrocyte fragment count is proposed in the present study to predict hemolysis in roller pumps. Methods： Five paired in vitro tests were conducted using the POLYSTAN pediatric pump（group A） and COBE pump（ group B）. Ten whole blood samples （400 ml ） were circled in the roller pump for 16 h. Erythrocyte fragments count and plasma-free hemoglobin （FHb） were measured before pumping and every two hours through circulation after four-hour-pumping. The morphological changes of erythrocyte were observed by scanning electron microscope. Results： The two groups＇ EFC and FHb levels were increased linearly during a long duration of pumping and linear regression of erythrocyte fragments count and plasma-free hemoglobin were correlated. Conclusion： Erythrocyte fragments count could be used as an index in evaluating the in vitro hemolytic properties of blood pumps.
基金supported by the National Key Research and Development Program of China(No.2019YFB2005202).
文摘This study presents a novel roller piston pump,in which a cam guide-roller type rolling support is adopted to replace the sliding pair support of the swash plate-slipper pair to achieve the oil suction and discharge of the piston cavity.In addition,the shaft distribution is used to replace the original valve plate distribution and the driving shaft is used as the distribution shaft to remove the valve plate structure,which greatly simplifies the design of the axial piston pump.Such a configuration largely reduces the number of sliding friction pairs of the pump,and avoids the influence of the sliding friction pair on it under high-speed and variable-speed conditions.Firstly,mathematical models of the mechanical and volumetric efficiencies of the roller pump are deduced respectively through force analysis and the compressibility equation.Based on the numerical simulation of MATLAB and AMESim,the effects of load pressure and rotational speed on mechanical and volumetric efficiencies are studied respectively,and it is verified that the roller pump has no structural flow pulsation.The prototype pump is then designed and built,along with a special test rig.The outlet pressure,outlet flow,and torque of the pump under different load pressures and rotational speeds are measured,and the mechanical and volumetric efficiencies of the prototype pump under various load pressures and rotational speeds are obtained.The experimental results are in good agreement with the simulated analysis.When the load pressure is 8 MPa and the speed is 5000 r/min,the mechanical and the volumetric efficiencies are 85.5% and 96.8%,respectively.When the speed is increased to 10000 r/min,the mechanical and the volumetric efficiencies are 66.7% and 95.6%,respectively.The experimental results show that the proposed roller piston pump has excellent efficiency under wide-speed and high-speed conditions and can be a potential solution as a fuel pump in aerospace fuel systems.
