Experimental Study of the Cavitating Flow on an Independently Heated Venturi Nozzle

Abstract

Despite the observation of change in the cavitation regime on a heated surface, the specific section of the wall surface that plays a more dominant role in this transition phenomenon remains unknown. This study experimentally investigated the effect of surface temperature of different regions on the cavitating flow in terms of the cavitation regime. The experiments were conducted using a convergent–divergent Venturi nozzle comprising two parts that could be heated independently. The Venturi nozzle could be fully or selectively heated at either the front, where the leading edge of the cavity sheet was located, or the rear, where the cavity sheet developed. The cavitation behavior under different heating conditions was investigated using high-speed visualization and fluctuating pressure measurements. Compared with the nonheated case, which exhibited sheet-cloud cavitation, the cavitation regime on the fully heated Venturi nozzle exhibited transient cavitation. The same transition phenomenon was also observed when only the front part of the Venturi nozzle was heated. In contrast, heating the rear part alone did not induce a change in the cavitation regime. Therefore, it appeared that the transition of the cavitation regime on a heated surface was mainly influenced by the temperature increase at the leading edge of the cavity sheet.