Dynamics of the liquid phase and of the bubbles are both investigated. The measurements are based on ultra fast Xray imaging performed at the APS (Advanced Photon Source) of the Argonne National Laboratory. The experimental device consists of a millimetric Venturi test section associated with a transportable hydraulic loop. Various configurations of velocity, pressure, and temperature have been investigated. The slip velocity between vapor and liquid is calculated everywhere both velocities can be obtained. Reynolds stresses are also calculated, and compared with the ones obtained in noncavitating conditions.
COBISS.SI-ID: 12266011
Results of experiments in a prototype turbine are presented. Cavitation was studied by measurements of vibrations, acoustic emission and pressure fluctuations. Results show good agreemenet among measurements and selection of operating point.
COBISS.SI-ID: 12824091
An experimental investigation has been made to detect cavitation ihydropower plant prototype suffering from leading edge cavitation in pump mode. Vibrations and acoustic emission on the housing of the turbine bearing and pressure fluctuations in the draft tube were measured and the corresponding signals were recorded and analyzed. Several estimators of cavitation were evaluated according to a coefficient of determination between the Thoma number and cavitation estimators. The best results were achieved with a compound discharge coefficient cavitation estimator that is based on the discharge coefficient and several rms estimators: vibrations, acoustic emission, and pressure fluctuations.
COBISS.SI-ID: 13375771
Experiments were conducted in six geometrically similar Venturi test sections where either width or height or both were scaled. Various types of instabilities are obtained, from simple oscillations of the sheet cavity length to large vapor cloud shedding when the size of the test section is increased. It confirms that small scale has a significant influence on cavitation. Especially the height of the test section plays a major role in the dynamics of the reentrant jet that drives the periodical shedding observed at large scale. Results suggest that the sheet cavity becomes stabile when the section is scaled down to a certain point because re entrant jet cannot fully develop.
COBISS.SI-ID: 12534555
Nowadays, due to lack of freshwater resources a sufficient wastewater management is an environmental concern. This global issue is resulting in the rapid growth of technologies for wastewater treatment. In this study a novel rotation generator of hydrodynamic cavitation is presented, which is used as a tool for pharmaceuticals removal in water. On presented machine analysis of hydrodynamics is made, where the extent and aggressiveness of cavitation is evaluated. The study has shown, that for a sufficient treatment, hydrodynamic cavitation with combination of hydrogen peroxide is needed. The removal of four pharmaceuticals (ibuprofen, ketoprofen, carbamazepine and diclofenac) was considered, where the over 80% effect was achieved. Various operating parameters such as the rotors geometry of the cavitation generator, pressure in the treatment chamber, temperature of the liquid, amount of hydrogen peroxide and time of exposure to the cavitation was investigated. The experimental results show that hydrodynamic cavitation has a good potential for efficient removal of pharmaceuticals what suggests to continue with research in this field and to consider an appropriate design for a commercial use.
COBISS.SI-ID: 13049115