| The prevalence rate of cardiovascular diseases in China is still rising.In recent years,artificial mechanical auxiliary circulation devices have been widely used in the treatment of heart failure.Mechanical auxiliary circulation can partially or completely replace the blood pumping function of the heart and become an effective method for the treatment of heart failure at present.Among them,the axial blood pump driven by magnetic force has better blood compatibility and lower blood temperature rise,which is an important means of mechanical auxiliary circulation.From the angle of phase difference detection,this paper studies the phase angle between magnetic driver and axial bleeding pump through simulation and experimental verification,and judges the stability of axial bleeding pump operation through the phase angle.The research contents are as follows:The axial torque of the driven rotor under different phase angles are simulated.The model of the driven rotor and the driven rotor is established.The phase angles are set to 0,22.5,45,67.5 and 90,and the relationship between the axial torque of the driven rotor and the different phase angles in the ideal state is analyzed.The theoretical value of the phase angle at the moment when the driven rotor loses stability and turns is obtained.The influence factors of the phase angle are studied and the phase angle of the unstable rotation of the driven rotor under no load is determined.Using the method of controlling variables,the factors affecting the phase angle are studied from the driving distance,rotating speed and driven rotor diameter as variables respectively.The influencing factors of phase angle were determined to provide guidance for the design of extracorporeal circulation experiment.The extracorporeal circulation experiment was carried out and the phase angle of instability and rotation of the driven rotor under liquid load was determined.According to the relevant influencing factors determined by the influencing factor research experiment,an extracorporeal circulation experiment table is designed and built,and a study on the influence of flow pressure on the phase angle is added on the basis of the relevant influencing factors.Using the method of controlling variables,the relationship between driving distance,rotating speed,pressure flow rate and phase angle is studied in depth.The linear regression equation between the relevant influencing factors and the phase angle is constructed and the reliability of the equation is verified.Through research,the following conclusions are obtained:The stability of shaft bleeding pump operation is affected by speed,driving distance and driven permanent magnet rotor diameter.With the increase of rotating speed and driving distance,the phase angle will become larger and the stability of shaft bleeding pump will become worse.At the same time,the larger the diameter of the driven permanent magnet and the smaller the phase angle,the more stable the operation of the shaft bleeding pump is under the condition that the driving distance and the rotating speed are unchanged.By analyzing the relationship between speed and phase angle,the linear regression equation of speed and phase angle under different driving distances is obtained.By analyzing the relationship between the driving distance and the phase angle,a positive correlation between the driving distance and the phase angle is obtained,and a linear regression equation between the driving distance and the rotational speed at the moment when the blood pump is unstable and turns off is obtained.By analyzing the relationship between pressure flow rate and phase angle,it is found that the phase angle decreases first and then increases with the increase of pressure.The phase angle is the smallest when the flow rate is about 1/2 of the maximum flow rate and the largest when the flow rate is 0.According to the external magnetic driving mode of axial flow bleeding pump,when the phase angle between important official bleeding pump and magnetic driver is about 83,the axial bleeding pump has the risk of losing stability and rotation,which has nothing to do with driving distance,rotating speed,pressure flow rate,driven rotor diameter,load and other factors.Relevant influencing factors can only affect the phase angle at the operation time of the blood pump so as to affect the operation stability of the shaft blood pump,but do not affect the phase angle value at the time of instability and rotation.In this paper,the phase angle of shaft bleeding pump at the moment of instability and rotation is verified and obtained through simulation calculation and experimental research.Through the analysis and processing of the data,the linear regression equations of the rotational speed and phase angle of the shaft bleeding pump under different driving distances and the linear regression equations of the critical rotational speed under different driving distances are obtained.It provides a basis for the stability evaluation of axial bleeding pump. |
