PROPELLER WAKE ANALYSIS BY LDV

Two phase sampling techniques are developed for the analysis of a propeller wake flow field by ldv with trackers in a cavitation tunnel. the measurements were carried out with water poorly seeded and basing the phase averaging of the velocity signals on the actual propeller position. the first technique follows the basic approach of phase averaging by angular triggering, with some enhancement to improve measurement efficiency. the second procedure uses the particle crossing the ldv measurement volume to trigger the acquisition; each sample, tagged with the blade angular position is then arranged in angular slots. the implemented technique prove to be complementary from the accuracy and efficiency point of view. using the angular triggering technique accurate investigations in the turbulent wake and tip vortex flows can be accomplished . The tracking triggering technique is instead useful for routine in the analysis of the propeller near wake evolution, in view of minimization of data acquisition time