Analysis Of Excitation Source And Vibration Characteristics Of A Three-screw Oil Pump

With the rapid development of the marine industry,the low-noise ship is the future trend.Since the equipment in the auxiliary system is one of the main sources of vibration and noise,it is of crucial importance to study the vibration reduction of such equipment.Due to its smooth and low turbulence characteristics,the three-screw pump is widely used in marine auxiliary systems,especially lubricating oil systems and fuel oil systems.In this paper,a three-screw oil pump unit driven by a diesel engine is taken as the research object,and the vibration characteristics of the motor driven test bench are studied by the excitation force calculation and reverse load identification.Based on the lumped parameter theory,the strength check of the diesel engine full-shaft system is carried out,which provides theoretical support for the selection of diesel-driven equipment.The main research contents are as follows:Firstly,the screws are mathematically modeled by vector algebra method,and the fluid excitation of the screw is solved by the surface integral principle.Based on multi-body dynamics theory and Hertz contact theory,the meshing excitation between the active screw and the driven screw is simulated by ADAMS software.Secondly,the finite element simulation modeling of the test bench is carried out.The finite element model is corrected by the test results of the natural frequency,and the vibration estimation of the three-screw pump unit under the action of fluid excitation and meshing excitation is performed.Thirdly,the frequency response function of the pump unit is calculated by Virtual.Lab software.Based on the inversion method and the minimum discriminant coefficient method,the equivalent excitation source position is studied.And the optimal combination of points is selected by the principle of the average condition number.The excitation source of the threescrew pump unit is identified based on the Tikhonov regularization,and the response estimation are carried out.Finally,based on the lumped parameter theory,the equivalent models of the screw pump test bench and the 16 V diesel engine test bench are established,and the correctness of the calculation is verified by the experimental torsional vibration results.On this basis,the fullshaft equivalent model of diesel engine is established,and the key component strength check and structural optimization design are carried out by step-by-step integration method,which provides theoretical support for the selection of equipment driven by domestic 16 V highspeed diesel engines.