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Abstract Cavitation inception in turbulent separated flow over blunt-faced flat plates and behind two-dimensional normal flat plates has been investigated experimentally. The study includes numerical simulation of noncavitating steady incompressible turbulent flow around the plates. Three blunt-faced plates of different thicknesses and three normal plates of different heights have been tested. The experiments were carried out in the test section of a water tunnel. The tunnel newly built at the Faculty of Engineering, Minia University, Minia, Egypt. Cavitation inception has been detected visually by watching the occurrence of a few minute bubbles, namely when cavitation was already macroscopic. The cavitation aspects were photographed simultaneously with the corresponding flow-measurements using a digital camera. The photos were later processed through a computer software and printed. The dissolved gas content has been measured by a dissolved gas content meter. Experimental observations have clearly shown that the first traces of cavitation appear as a series of small discrete bubbles in the free shear layer away from the solid surface near the leading edge of the bluntfaced plates and immediately behind the upper and lower edges of the normal plates. The cavitation inception indices tend to decrease with increasing freestream velocity. The physical appearance of cavitation and the trend of cavitation inception indices suggesting that it is related to the small-scale vortices and associated large pressure fluctuations. The high audible sound associated with the inception implies that the cavitation is vaporous. It was also found that both the blunt-faced plate thickness and the normal plate height have no effect on the cavitation inception indices. |