摘要
在小型循环式水洞中试验研究了沙粒粒径对高速水流空蚀的影响。由筛分法获取5种沙粒的典型中值粒径(0.08,0.25,1,2,3 mm),配制相同含沙量S=12 kg/m^(3)的挟沙水样,用红外测沙仪实时量测高速挟沙水流的含沙量。对于每一粒径的挟沙水流,利用压力数据采集系统实时采集水洞工作段的压力,并与清水情形进行比较。制作了水灰比W/C=0.4,灰砂比C/S=1.5,7 d龄期强度fcu,k=17.8 MPa的混凝土试件,安放在水洞工作段混凝土试件盒中进行4 h的空蚀试验,对每一粒径在不同流速时的混凝土试件空蚀量进行了比较。结果表明,在含沙量S=12 kg/m^(3),V=38.2 m/s工况下,空化段挟沙水流压力随粒径的增大而降低,致使初生空化数减小,从而促进空化的形成;空蚀段挟沙水流压力则随粒径增大而升高,具有促进空蚀的作用;混凝土试件的空蚀程度随粒径的增大而加剧,并且流速提高使空蚀范围进一步扩大。
Effect of the variation of sand grain size on cavitation erosion of concrete in sand-bearing water flow was experimentally investigated via a small looped water tunnel. Sand grains with five typical median particle sizes(0.08, 0.25, 1, 2 and 3 mm) were obtained by sieving method. For each grain size,the sand-bearing water samples with the same sand content S=12 kg/m^(3)for each given sand grain size were prepared respectively. The sand content of high-speed sand carrying water flow was real-timely measured by an infrared suspended solid analyzer. The pressure at the working section of the water tunnel for each sand-carrying flow with a given grain size was acquired by pressure data acquisition system in real-time, then of which a comparison was made with the case of clear water. Concrete specimens with water-cement ratio W/C=0.4, cement-sand ratio C/S=1.5,7 d aging strength fcu,k=17.8 MPa were poured.Afterwards, the specimen was placed into a specimen box fixed in the working section of water tunnel to undergo cavitation erosion test for 4 h by different flow speeds for one sand carrying water with a given sand grain size. The results showed that for the case with send content of S=12 kg/m^(3)and flow speed V=38.2 m/s, the flow pressure at cavitation zone decreased with the increase in sand grain size, which resulted in decrease in the incipient cavitation number and promoted the formation of cavitation;the sand carrying flow pressure at cavitation-erosion zone increased with the increase in sand grain size, which could promote the cavitation erosion. The cavitation erosion level of the concrete specimen was aggravated with the increase in sand grain size, and the cavitation erosion range was further spread with the increasing flow velocity.
作者
董志勇
徐旭意
李宇航
DONG Zhiyong;XU Xuyi;LI Yuhang(College of Civil Engineering,Zhejiang University of Technology,Hangzhou 310023,China)
出处
《中国腐蚀与防护学报》
CAS
CSCD
北大核心
2023年第1期166-172,共7页
Journal of Chinese Society For Corrosion and Protection
基金
国家自然科学基金(51979248)。
关键词
沙粒
粒径
混凝土表面
空蚀
高速水流
sand grain
grain size
concrete surface
cavitation erosion
high velocity flow
