Research on the Theory and Simulation of Torsional Vibration for CODAD Systems

摘要

Two machines driving one propeller, especially CODAD (Combined Diesel and Diesel) has been widely used in marine propulsion shafting for power performance and fuel economy, but there were few researches about the device for shaft vibration. In this paper, based on the independent design multi-functional test bench of the marine power plant, the torsional vibration calculation method of the test bench was established and the calculation results were gotten by the theory analysis. Then the corresponding system simulation model was set up on the basis of constructing discrete dynamics model of the two diesel engines with different cylinders, and response curves of the shaft under the different rotational speed were obtained. The resonant frequency of the shaft system was estimated through Fast Fourier Transform Algorithm (FFT), and the simulation result has better consistency with the theoretical value, which proved that the natural frequency in complex shafting could be obtained by the simulation method.