Study on Internal Flow and Energy Characteristics of Axial Flow Pump at Different Rotational Speeds
Long-term constant flow delivery of blood pumps is a health risk for implanted patients,and variable speed operation is an effective way to realize pulsatile flow delivery,but too high speed or deviation from the design speed will lead to internal flow turbulence and a decrease in energy efficiency.In this regard,the study establishes blood pump and nozzle models,adopts numerical simulation and visualization experimental methods,and combines entropy production theory to investigate the internal flow and energy loss characteristics of the blood pump at different rotational speeds.The results show that:the flow field energy loss and shear stress increase significantly with the flow intensity,the turbulent entropy production in the flow field is much higher than the direct entropy production,and the velocity gradient has a key effect on the entropy loss and shear stress;the energy loss of the blood pump increases with the increase of rotational speed,the entropy production in the impeller area accounts for more than 80％of the total energy loss,and the turbulence entropy production of the back-vane increases significantly under the high rotational speed;the inlet and outlet of the impeller blade and the back-vane blade have the highest local entropy production,the difference angle between the liquid flow angle and the blade direction as well as the high rotational speed are the central factors affecting the energy loss.
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