The application of particle image velocimetry for the analysis of high-speed craft hydrodynamics

The particle image velocimetry (PIV) technique has become a reliable method for capturing the velocity field and its derivatives, even in complex flows and is now also widely used for validation of numerical codes. As the imaging system is sensitive to vibrations, the application in environments such as towing tanks makes it a challenging task. Especially when operating the towing tank carriage at higher speeds structural vibrations increase significantly. However, to apply this technique for the analysis of planing and semi-planing vessels, this is absolutely necessary. To assess the ability of a PIV system to capture the flow features close to a ship model while being towed at high speeds, a stereo PIV system was installed in the TU Delft towing tank. Measurements are conducted in the transom region of a generic high-speed vessel hull with a flat bottomed aft section, which is equipped with an interceptor at the transom. It is shown that with increasing carriage speed, vibrations of the imaging system increase, which ultimately can affect the quality of PIV recordings. The effect of vibrations is quantified by analysis of successive recordings and based on this, a shift correction is applied. A comparison with numerical results shows that the flow around the interceptor is well captured by the PIV system