Net and Gross Thrust in Waterjet Propulsion

The measurement of the net thrust of a waterjet unit is a cumbersome task and thus as an alternative, the thrust of the waterjet system is expressed based on the momentum flux change through the waterjet unit, called gross thrust. The relation between net thrust and gross thrust is not fully understood, and in the current paper this relation is investigated by employing numerical simulations of the flow around a planing waterjet propelled hull. The validation of the bare hull and self-propelled hull simulations is carried out through comparison of the computed results with experimental data.