493 



containing cavitating as well as non-cavitating Here the most probable cause is that the cavitation 



periods indicate that the fluctuations were generated started resonance vibrations in some structure, 



by cavitation (Figure 10, 7 Hz, Figure 11 and 12). These vibrations probably cause disturbing errors 



Inspection of the films shows, however, that no in the pressure signal at some fosc mainly in the 



cavitation is visible on the hydrofoil or about region 3-7 Hz, and quantitative results from such 



0.5 chord-lengths downstream it (Figure 9, 11, 3 Hz). conditions must be used with care. 



