环形狭缝型旋转式水力空化器的空化特性与降解能力

Cavitation characteristics and degradation capability of an annular slitrotating hydraulic cavitation generator

为了开发新型高效的有机污水处理方式,探究新型旋转式水力空化器的空化特性,该研究综合高速摄影技术和压力脉动测试技术对环形狭缝型旋转式水力空化器在不同流量工况下的内部空化特性进行试验研究,并选取亚甲基蓝作为降解试剂,分析该空化器对难降解有机物的降解能力。试验结果表明,空化器内部存在4种空化形式:环形狭缝结构前缘空化、盲孔内空化、盲孔后缘空化以及环形狭缝结构后缘空化,且盲孔内空化和环形狭缝结构后缘空化占据主导;环形狭缝结构后缘空化存在明显的准周期性生长、脱落和溃灭过程,其演变准周期约为1.78 ms,导致蜗壳出口压力脉动离散特征明显;空化器在各流量工况下具有良好的输送性能,且随着流量的增大,经历了初生空化到云状空化的转变,当流量增大至36 m^(3)/h时,空泡团在周向的最大长度约为26 mm,在径向的最大宽度约为14 mm,当流量增大至37.5 m^(3)/h时,狭缝前缘空化沿着周向展开,形成“V”型空化覆盖部分盲孔,空化器内部空化程度明显加剧,蜗壳出口压力脉动主频(叶频)幅值增大,宽频脉动增强;空化器对亚甲基蓝的有效降解存在最佳流量工况和最佳溶液初始浓度,即当流量工况为36 m^(3)/h,溶液初始浓度1.5 mg/L时,在该条件下,空化器对亚甲基蓝的降解能力最强。该研究对于难降解农业有机污水处理具有一定的参考意义。

A groundbreaking and remarkably efficient strategy can be expected to be formulated for the mitigation of organic wastewater in recent years.In this study,an elaborate and all-encompassing investigation was implemented to determine the intricate mechanism behind the cavitation characteristics of a rotary hydraulic cavitation apparatus.A series of techniques were seamlessly integrated with cutting-edge and sophisticated high-speed photography along with precision-oriented pressure fluctuation testing.A systematic analysis aimed at the innermost cavitation flow dynamics within the confines of a circular narrow slit configuration.There was the very heart of a rotary hydraulic cavitation generator.This comprehensive experimental inquiry yielded an invaluable reservoir of insights across an array of dynamically varying flow conditions.An additional layer of depth was added to select methylene blue as the designated degradation reagent,thereby enabling an astute and comprehensive evaluation of the cavitation device's remarkable proficiency in breaking down and degrading recalcitrant organic substrates.The empirical revelations served to unveil a rich tapestry of cavitation manifestations,each weaving a unique narrative within the apparatus's intricate landscape.These manifestations encompassed the inception of cavitation at the forefront of the circular narrow slit structure,the subsequent propagation of cavitation within the confined precincts of blind holes,the remarkable emergence of cavitation formations at the trailing edge of these very same blind holes,and the subsequent ripple effect culminating in cavitation events at the trailing edge of the circular narrow slit structure.Two prominent modes were highlighted in this diverse panorama:the cavitation occurrences within the confines of the restricted blind holes and the eloquent cavitation events materializing at the trailing edge of the circular narrow slit structure.Furthermore,the cavitation unfolding at the trailing edge of the circular narrow slit structure exhibited an intriguingly rhythmic and quasi-periodic sequence of events.A cyclic progression was characterized by expansion,detachment,and ultimate collapse.This mesmerizing cycle resonated with a temporal cadence hovering around the 1.78 ms mark,indicating the inherent dynamics.Subsequently,some fluctuations were captured in the form of discernible pressure at the outlet of the intricate volute casing.This compelling cavitation generator was the nucleus of this elaborate investigation.An unparalleled performance was achieved for the fluid conveyance over an expansive spectrum of dynamic flow conditions.The landscape of cavitation underwent a transformative journey:transitioning from the nascent phase of incipient cavitation to the captivating allure of the cloud cavitation phenomenon,as the flow rates surged and surged further still.The cloud cavitation shared the unfurling across the circumferential realm with a regal length approximating 26 mm and then coupled with a radial span of around 14 mm at the notable juncture of 36 m^(3)/h flow rate.An intensification of cavitation dynamics was obtained for the further surge in the flow intensity at 37.5 m^(3)/h brought forth.There was the distinctive"V"-shaped cavitation pattern in the leading edge of the narrowslit structure with a captivating.There was an intricately woven tapestry that partially enveloped the confines of the revered blind holes.The enhanced intensity of cavitation shared profound repercussions.The amplitude was amplified for the blade passing frequencies.Consequently,there were amplified and richly textured broadband pressure fluctuations.Furthermore,the cavitation generator demonstrated an optimally calibrated capacity for the degradation of methylene blue under meticulously tuned flow and initial solution concentrations.The zenith of the degradation potential(a crescendo of sorts)was discerned at the distinguished crossroads of a 36 m^(3)/h flow rate in the initial solution concentration with a precise 1.5 mg/L.The finding can provide a strong reference for agricultural organic wastewater treatment.