| Reciprocating cascading air compressor is an essential equipment of the ship. And it isalso one of the main sources of vibration and noise. As the related requirements of the GreenShip continuously improve, how to decrease the vibration and noise of the compressors hasbeen a crucial topic. This thesis analyzed the dynamic characteristics of a certain typedreciprocating cascading air compressor. More precisely, the research is conducted in theseaspects, like the mechanical property and the load sources characteristics. It aimed to explorethe methods of the dynamic analysis and vibration forecast for the compressor, so as toprovide the references for its low noise design.Firstly, the thermodynamic analysis of the compressor was conducted to test the cylindergas pressure. The results were coincident with the data provided by the factory. Then thedynamics and kinematics calculation for the crankshaft and connecting rod mechanism weredone, and the main loads applied on the pistons, connecting rods and crankshafts were got.Additionally, the load status of the compressor was analyzed. The transient speed and cycleirregularity of the crankshaft ware calculated based on the piston pressure. The journal centerlocus of the crankshaft was figured up by using short bearing approach, which providedevidences for balancing the second order inertia force.Besides, according to the lumped parameter method, the shafts were simplified toequivalent torsional vibration model. The free and forced torsional vibration wereprogrammed. Then the natural frequency, principal modes and response of the forcedvibration were computed. The additional moment and stress of the torsional vibration werealso analyzed. The optimization was further proposed by changing the coupling parameter.Eventually, the finite element model of the compressor was built. The load sourcesidentification was carried out by using the domain least square method(LS) with the testingacceleration respond. And the forces transformed to the foundation were calculated. Throughthe in-depth analysis, the compressor was found to have the acoustic short circuit, whichprovided reference for the later repair work of the compressor. |
