| Cavitating water jet wins more and more favour of people for its safe,clean and efficient advantages, and is widely used in cleaning, cutting,breaking, water treating, etc.Combining cavitation theory with choking phenomena of gas-liquidtwo phase flow, we have developed a new type of hydrodynamic cavitator,i.e. choking cavitator. In experiment, the cavitation noise signal is collectedwith hydrophone, and the features of power spectrum of cavitation noiseproduced by the different nozzles are analyzed comparatively. It is obtainedthat the choking cavitator has a flat roof in power spectrum curve which isa broadband and higher energy. Using energy ratio analysis method, thedifferent structural parameters of choking cavitator on its cavitationperformance are analyzed. The results show that the back pressure is themost significant effect on cavitation performance of choking cavitator, andthe influence of the standoff distances is the smallest.The phenol solution, which pH is6.5, is taken for artificial wastewaterand the treatment time is60min. The phenol solution is treated withchoking cavitator, oscillating nozzle and conventional nozzle. By way ofcontrast analysis of the experimental results, it is observed that the removalrate of phenol with choking cavitator reaches41.59%, being4.5and6.6times that of oscillating nozzle and conventional nozzle differently. Thechoking cavitator has a unique advantage of degradation of phenol in waterin comparison with the other nozzles. Meanwhile, it is demonstrated thatthe back pressure affects indeed on the cavitation performance of chokingcavitator. When the back pressure hole diameter is4mm and5mm, theremoval rate of phenol is all above40%. The removal rate of phenol is lessthan that of ordinary nozzle while the back pressure hole diameter is6mm.Choking cavitator has an excellent cavitation performance and issuitable especially for the field of refractory wastewater treatment byhydrodynamic cavitation. |
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