Research On Static Balance Measuring Method Of Marine Propeller And Static Characteristics Of Hydrostatic Bearing

As the power unit of the ship,the existence of the static unbalance of the marine propeller will cause vibration,accelerate the abrasion of the shafting,reduce the service life,and affect the stability of the whole ship.Therefore,the propeller must be tested and corrected before leaving the factory.The traditional horizontal static balance method is still used in many cases because of its simple structure and intuitive observation.But its shortcomings are also obvious,the detection accuracy,measurable propeller quality and detection efficiency are not high.With the development trend of large-scale propeller,it is urgent to research and develop the method and device of propeller static balance detection to meet the static balance detection requirements of high precision,large load and automation.Based on this,the following work is carried out:Firstly,based on the mechanical principle of rotor static balance,the basic composition and working principle of horizontal static balance detection method are introduced,and the influence of bearing friction torque on detection is studied.The analysis shows that when the friction moment is M,the minimum detectable static unbalance is 2M/R.In order to improve the detection accuracy and increase the measurable quality of propeller,a vertical static balance detection method based on the static pressure suspension theory is proposed.Based on this method,a set of static unbalance detection algorithm is proposed,and the mathematical expression of the magnitude and orientation of the static unbalance is derived.Secondly,hydrostatic bearing,the key component of vertical static balance detection method,is taken as the research object,and the mathematical model of the bearing capacity,oil film pressure field,leakage and other characteristics of hydrostatic bearing is derived.Then,the numerical analysis is carried out with MATLAB,and the changing rules of static characteristics are obtained.It is found that the included angle?₁ and?₀ and the spherical radius R of the hydrostatic bearing have a great influence on the bearing capacity.When the included angle?₁ is less than 85°,the bearing capacity can be increased by16.7%on average for every 10°increasement.At the same time,the thickness of oil film h,the kinetic viscosity?of oil,the structural parameters of capillary throttle and oil pressurep_r provided by system also play an important role in the static characteristics of hydrostatic bearing.Then,based on the principle of CFD,the steady flow field of hydrostatic bearing is simulated by FLUENT software,and the distribution law of pressure field and velocity field of hydrostatic bearing is further studied.In order to avoid the offset of the axis of the ball head and the ball socket,two kinds of hydrostatic bearings with balance groove,rectangular balance groove and triangular balance groove,are designed.Then the steady flow field of hydrostatic bearing with groove is simulated.The results show that the bearing capacity of hydrostatic bearing with triangular groove is larger and its leakage is smaller than that of hydrostatic bearing without groove.In addition,taking the bearing capacity,oil film stiffness and leakage of hydrostatic bearing as the optimization objective,the structural parameters of hydrostatic bearing are optimized by using the genetic algorithm.After optimization,the leakage coefficient is reduced by 72.71%,the bearing capacity coefficient is increased by 7.54%,and the oil film stiffness coefficient is increased by 3.38%.Finally,according to the principle of similarity,the experimental prototype of vertical static balance detection system is designed and built.Based on the experimental prototype,the measurement methods of friction moment of hydrostatic bearing,sensitivity of experimental prototype and accuracy of static balance detection are put forward.The measurement results show that The magnitude of friction moment of hydrostatic bearing is very small and increases with the increasement of oil pressure.The static balance detection accuracy of the experimental prototype is within±0.4kg...