Study On The Monitoring Theory And Method Of Power Flow Analysisof Large Marine Propulsion Shafting

Marine power plant is an organic combination of all kinds of mechanicalequipments and systems that serve for energy production, transmission, andconsumption. Its main task is to provide various kinds of energy for ship, ensure thenormal order of the marine sailing and operations, and guarantee the safety ofpersonnel life. As the "heart" of the ship, marine power plant provides propulsion andsecondary energy for normal navigation, operations, combats, and other needs of theship it. Recent years, the proportion of large or ultra-large ships of the total number ofworld ocean ship is increasing. Large-scale development of the ship is not only anurgent demand for marine economic development at home and abroad, but also aproduct supported by frontier ship basic theory and the advanced shipbuildingtechnology. The study of condition monitoring theory and method of large marinepropulsion shafting is still a problem that has not been completely overcome; it hastheoretical guiding significance and practical value to the safety of marine navigation.Through the research on the energy flow distribution characteristics of large shippropulsion shafting, get the control of state information of the ship propulsionshafting, such as its energy flow dynamic distribution characteristics and power flowtransmission technologies in real time, to reveal the dynamic characteristics of shippropulsion system. Compared with the classical vibration analysis and the oil analysistheory, the method based on power flow is easier to explain the energy distributionand transmission mechanism.With a large marine propulsion shafting as the object, in this paper, the mainwork is as follows:1. Ship shafting operating characteristics and its influencing factors have beenanalyzed. The marine propulsion shafting propeller vibration exciting force formulaand diesel engine vibration exciting force empirical formula and the theoreticalcalculation method were summarized. And we also analyzed the vibration force’seffect on the propulsion shafting. With an8530TEU container ship propulsion shafting as the research object, we provide the changing characteristic value ofpropeller bearing force in all direction when propeller rotates for one revolution underthe rated speed. We studied the influence factors of the vertical displacements of theship propulsion shafting bearings, pointed out that factors such as shafting inertia load,initial alignment, the propeller exciting force, and deformation of the hull under waveloading, can lead to different degrees of shafting forced displacement of each bearing.And we also studied the dynamic characteristics of bearing oil film’s stiffness,damping, force, and equivalent bearing displacement, etc.2. Proposed a computing method for shaft system energy distribution of largeship propulsion shafting under torsional vibration, axial vibration, whirling vibrationand coupled vibration based on the theory of the power flow. According to the theoryof power flow, we provided the dynamic equation, constitutive equation, therelationship between displacement and strain, the relationship between displacementand velocity, and boundary conditions of a typical bar under the action of tension andcompression, torsion and bending, and deduced the relational expression of poyntingvector and energy flow location. Combining with the bond graph theory, weestablished the bond graph model of the8530TEU container ship propulsionshafting. Based on the theories above, we deduced the power flow calculationformula of the shafting under longitudinal vibration, torsional vibration, whirlingvibration and coupled vibration of different boundary conditions.3. Linear simplified physical model and nonlinear simplified physical modelabout shaft system is established under the coupling of the "hull-bearing-film-shaft",and the "hull-bearing-film-shaft" coupling control equation is deduced respectively,and then the power flow transfer characteristics of the coupling model are analyzed.4. Established a finite element model of8530TEU container ship shafting usingfinite element method. Take the8530TEU container ship propulsion shafting as anexample, Based on the finite element method, we studied the shafting energy flowdistribution characteristics and laws such as vertical displacement distribution, torquedistribution, stress and strain distribution and strain energy distribution under thecondition of inertial load, propeller exciting force, and reasonable bearing centering. 5. Develop a non-contact inductive power supply device based on magneticcoupling resonance technique, to carry out the non-stop continuous on-linemonitoring to energy signal by shafting monitoring device. Thereby reliable datacollection can be carried out in ship propulsion shafting performance comprehensiveexperimental platform and full scale test, improving the precision of test method ofthe ship propulsion shafting performance parameters. Shaft power, shafting torsionalvibration and longitudinal vibration were tested on ship propulsion shaftingcomprehensive performance test platform for imitation of propeller shafting, and thetest data was analyzed.Combining the theory of power flow, we analyzed the running characteristicsand dynamic response of ship propulsion shafting, deduced the power flowdistribution calculation formula of each coupling subsystem of ship propulsionshafting. From the perspective of theoretical analysis and finite element simulation,we studied the energy flow distribution characteristics of typical shafting macropower distribution and micro power flow transfer, proposed a condition monitoringtheory of large ship propulsion shafting energy flow distribution; thus to providemethods and technical supports for optimal design, installation, performancemonitoring and maintenance of large ship propulsion shafting, and to providereasonable basis for repair and maintenance to extend the service life of the ship.