Experimental investigations and numerical modeling of a mixed flow marine waterjet

Abstract

Recently, waterjet propulsion has gained great commercial interest as the shipping industry trends toward faster passenger ferries and other fast transport vessels. The work presented in this thesis was part of a larger effort to improve the capabilities and performance of a mixed flow marine waterjet used in such high speed marine applications. An experimental test faciity was constructed and employed in the testing of a mixed flow marine waterjet rotor, stator and housing set. Full description of the facility and waterjet test procedures are discussed. The pumpset was designed using a coupled Lifting Surface/RANS procedure by Taylor et.al.[35] and was built and tested as part of the work presented in this research. Detailed measurements of the pump performance is described including pump curves, tipgap studies, inlet, midstage and outlet velocity and pressure profiles in an axisymmetric inflow. Full accounting for losses including rotor and stator loss profiles as well as a full pumpset energy balance is presented. From the results of the experiment, dominant losses were found near the tip/duct junction casing along with a large and unexpected increase in swirl in this region. Detailed numerical modelling of this pumpset was performed using both a Lifting Surface/RANS procedure and a Lifting Surface/Euler solver. Effects of losses were modelled as well as tipgap effects. Prior work had developed these coupling procedures but the computationally efficient Euler coupling lacked the introduction of loss and drag induced swirl. This loss coupling was added to the model and the analysys results are discussed. Also, a model to align the wakesheet with the local flowfield in the Lifting Surface solver was developed and these results are discussed.