CFD Simulations of the Flow through a Waterjet Installation

Abstract

With the aid of modern computational fluid dynamics (CFD) tools it has become possible to calculate and visualise the flow through a complete waterjet installation. This can help to enhance the understanding of the occurring physical phenomena and this will lead to further improvements of the complete installation. Calculations are made with a steady-state multiple frame of reference (MFR) approach and with a fully transient moving mesh method. Inlet and pump CFD models have been validated separately with available experimental data. Agreement between measurements and CFD results is good for both. The numerical models of inlet and pump are combined to form a complete waterjet installation. The thrust and torque predicted with this model agree very well with the values obtained with traditional software. A concentration scalar has been introduced to visualise the suction stream tube. With this scalar the averaged velocity of the ingested water, and consequently the wake fraction, is determined. Results of transient calculations are used to determine pressure fluctuations on the impeller blade and in the stator bowl.