Multiphase DFBI Analysis of an Outboard Gearcase & Mount System

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CFD analysis is widely used for evaluating the hydrodynamic efficiency of marine components such as gear cases and propellers. A gear case fixed inside a domain, with or without a propeller, can be run using a quasi-steady multiphase CFD approach, similar to a water tunnel test, to calculate the forces and moments on the gear case. For more insight into the effect of dynamic forces, the gear case can be allowed motion with Six Degrees Of Freedom (6DOF) and coupled to the engine mounts to provide flexible constraints. Mercury Marine has been evaluating the use of the multiphase Dynamic Fluid Body Interaction (DFBI) method to evaluate the effect of hydrodynamic loads at high speeds on the gear case and mount system. In the present study, theoretically derived equations are used to validate the analysis results for a simplified model with a single rotational DOF and with the gear case partially constrained by springs representing the engine mounting system.

Author Company: 
Mercury Marine
Author Name: 
Sanjal Gavande