ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

Centrifugal pumps are widely used to deliver liquid media in agriculture, pharmacy, industry, petrochemical industry, etc. Compared with the case delivering pure liquid such as water, centrifugal pumps not only have lower efficiency but also are subject to severe vibration, noise and erosion when delivering cavity two-phase flow, leading to the deterioration of flow field and even the shortage of service life. The cavitation flow in centrifugal pump performs strong instabilities, thus a method of a tiny obstacle fitted on the blade surface was proposed to suppress the cavitation development on a ns=32 model pump. The unsteady cavitation flow varied with cavitation number in centrifugal pump was simulated by modified SST k-ω turbulence model combined with Kubota cavitation model. The results showed that the head of centrifugal pump with obstacle was decreased within 5% at various flow rate and within 3% at design point, the efficiency was decreased within 3% at various flow rate and 1.2% at design point, the head with obstacle was great improved when cavitation flow developed. The obstacle can enhance the turbulent kinetic energy near the blade wall and reset the absolute pressure distribution, which can suppress the cavitation at different stages in centrifugal pump. The obstacle can optimize the flow structure and degrade the vortex intensity near the suction side of blade especially the area close to the tongue. The obstacle can decrease the cavity volume at varied cavitation number and the cavity volume keep attenuating when cavitation developed. The obstacle can cause small magnitude of the disturbance on the pressure frequency spectrum. The effects of cavitation suppression were optimal when the bubbles reached close to the obstacle.