| The ship during the voyage,the shafting operation will be affected by Shaft condition?the excitation of the main engine and the propeller.In some large ships,diesel engines and shafts are directly connected.Because there is no deceleration gear box between the diesel engine and the Shaft,the combustion conditions of diesel engine will produce the direct effects on the shaft vibration,so it is necessary to study the influence of combustion condition of diesel engine on propulsion shafting torsional vibration.In this paper,a 8530 TEU container ship as the research object,the influence of combustion conditions of marine diesel engine on the shafting torsional vibration are analyzed by Virtual Prototyping Technology,this paper mainly do the following works:1)Cylinder pressure's simulation of diesel engine under normal and abnormal combustion conditions.For the problem of the influence of normal and abnormal combustion of diesel engine on the cylinder pressure.The finite element method is used to simulate the cylinder pressure of the diesel engine which is the normal fuel injection?the different fuel injection quantity and the fuel injection advance angle,derived cylinder pressure curve.Under the condition of normal fuel injection of diesel engine,if the diesel engine injection advance angle is too larger,the ignition delay period will become longer,there will be more fuel injected,the work of the diesel engine will be rough;In the normal working condition of diesel engine fuel injection advance angle,when the fuel injection quantity is too small,the cylinder pressure will be not up to the requirements,the engine power declined,and even lead to cylinder flameout;2)The building of the 3D model and rigid flexible hybrid of Propulsion shafting,the free vibration of shafting be calculated by using the method of the Holzer,generating the amplitude and torque diagram of the free torsional vibration of shafting.According to the amplitude and torque diagram of the free torsional vibration of shafting,the output measurement point of forced torsional vibration of shafting is selected.The three-dimensional model of the ship propulsion system is established,and the rigid flexible hybrid system be generated by ADAMS software.The amplitude and torque diagram of the free torsional vibration of shafting can be found that the absolute value of the curve in the two figures is basically the opposite,and the "node" in the free vibration amplitude diagram is the "peak" in the vibration torque diagram of the shafting in the first 6 order modal;3)The simulation of torsional vibration of shafting under normal combustion condition of diesel engine.For the effects of normal diesel combustion pressure on the torsional vibration of the shafting,the forced torsional vibration is calculated in ADAMS software based on the finite element method and multi-body dynamics method,and the torsional angle of the shaft is 6.11×10-3rad under the normal combustion of diesel engine;4)The simulation of torsional vibration of shafting under abnormal combustion condition of diesel engine.The influence of abnormal combustion on the torsional vibration of shafting is simulated and analyzed by the virtual prototype technology,and summarized the influence law.The results show that the torsional vibration of the shaft is related to the firing sequence of two flameout cylinders,and the torsional angle of the stern is wavy shape with the change of the flameout cylinder.the two cylinders'(including No.1 cylinder)ignition angles of the crankshaft closer,the greater the torsional amplitude of the shaft.Under the condition of abnormal two cylinders fuel injection advance angle and fuel injection quantity,the torsional angle of the stern is wavy shape with the change of the cylinder firing sequence.The larger difference between the two cylinders'(including No.1 cylinder)injection advance angle and the normal fuel injection advance angle,the greater the torsional amplitude of the shaft. |
PDF Full Text Request