Research On The Dynamic Response Of Twin Engine Parallel Propulsion System

The COGAG propulsion system is a relatively advanced combined power unit widely used by large ships in developed countries.Since the last century,about 40% of all types of ships built with a combined power plant in the world have adopted a combined fuel-fired power plant.At present,in order to ensure the safety of operation,the safety factor method is generally used to combine / decommission at a specific operating point.According to the requirements of contemporary marine defense,the ship’s power unit should be able to achieve operating conditions in the shortest time without sacrificing part of the fatigue life,in order to cope with the ability to deal with various emergencies,and the warships can quickly evacuate during cruise to avoid evasion Missiles and their ability to leave the battlefield within a short period of time play an important role.This requires that the ship’s gas turbines have the performance of reliable,rapid and large-scale change of working conditions,which can greatly improve the survivability and combat capability on the battlefield.Research is very necessary.Based on the above background,this article takes a COGAG ship’s propulsion shafting as the research object,studies and simulates the dynamic load caused by rapid parallel passing,analyzes the modeling method for the ship’s propulsion shafting,and the principle of dynamic response calculation.On this basis A simplified COGAG ship propulsion shafting dynamics simulation model and a gear dynamic meshing model were established on the basis of this.The dynamic load generated by rapid parallel vehicle loading was discussed and obtained;a lumped parameter model of the shafting response calculation was established,and a finite element analysis based on A hybrid model is used to perform loading calculations on the model;a test bench for the shafting system is established to simulate the rapid on-boarding process,and a set of on-line dynamic load monitoring system is used to test the response of the shafting system.The specific contents of the study include:（1）Theoretical research on dynamic response analysis of COGAG ship propulsion shaftingThe characteristics of each part of the real ship COGAG propulsion shafting system were studied,and the modeling method that correctly reflected the dynamic characteristics of each part was studied.The time variation of the meshing stiffness of parallel gears and the mechanism of gear meshing excitation during the meshing process are explained.The advantages and disadvantages of the lumped parameter method of the dynamic response calculation model of the shafting system and the finite element analysis method based on ANSYS are analyzed.Modeling analysis provides theoretical guidance.（2）Simulation of Dynamic Load GenerationThe key components of the COGAG device dynamic load SSS clutch and parallel gear are researched.The structure and working principle of the SSS clutch are studied.A three-dimensional model is established to simulate the parallel process.Dynamic simulation of the simplified parallel device in Adams is performed.The analysis obtained the parallel shock load.A three-dimensional model of gear meshing was established,and a rigid-flexible hybrid model of meshing gears was established using ANSYS and Adams.Dynamic simulation analysis was performed to obtain the timevarying torsional stiffness of the gear and the dynamic load generated by gear meshing,and to provide load input conditions for the dynamic response calculation.（3）Calculation of shaft dynamic responseBased on the D’Alembert’s principle,a numerical solution method for dynamic response was deduced.The calculation process of the dynamic response of the shafting based on the New Mark-β method was summarized.A MATLAB calculation program was written to load the propeller excitation torque,parallel shock torque and gear meshing excitation.The numerical method based on time domain is used to solve the problem,and the correctness of the calculation method is verified.A continuousdiscrete mass point hybrid model was established,and the response calculation was performed in the finite element analysis software ANSYS.（4）Development of rapid parallel test and dynamic online monitoring systemSet up a simulation test bench for the COGAG device,and develop a dynamic online monitoring system for the shaft system to simulate the rapid parallel operation conditions.Through the collection and analysis of test data,it was shown that an impact load was generated during the rapid paralleling process,and the measured shaft segment torque value was compared with the theoretical calculation.