Computational fluid dynamics of four-quadrant marine-propulsor flow

Computational fluid dynamics results are presented of four-quadrant flow fo r marine-propulsor P4381. The solution method is unsteady three-dimensional incompressible Reynolds-averaged Navier-Stokes equations in generalized co ordinates with the Baldwin-Lomax turbulence model. The method was used prev iously for the design condition for marine-propulsor P4119, including detai led verification and validation. Only limited verification is performed for P4381, The validation is limited by the availability of four-quadrant perf ormance data and ring vortex visualizations for the crashback conditions. T he predicted performance shows close agreement with the data for the forwar d and backing conditions, whereas for the crashahead and crashback conditio ns the agreement is only qualitative and requires an ad hoc cavitation corr ection. Also, the predicted ring vortices for the crashback conditions are in qualitative agreement with the data. Extensive calculations enable detai led description of flow characteristics over a broad range of propulsor fou r-quadrant operations, including surface pressure and streamlines, velocity distributions, boundary layer and wake, separation, and tip and ring vorti ces. The overall results suggest promise for Reynolds-averaged Navier-Stoke s methods for simulating marine-propulsor flow, including off-design. Howev er, important outstanding issues include additional verification and valida tion, time-accurate solutions, and resolution and turbulence modeling For s eparation and tip and ring vortices.