不同温度水体空化水动力脉动特性的试验研究  

Experimental Study on Hydrodynamic Characteristics of Cavitating Flows around Hydrofoil under Different Water Temperatures

作　　者：时素果[1,2] 王国玉[1] 胡常莉[1] 高德明[1] 

机构地区：[1]北京理工大学机械与车辆学院,北京100081 [2]北京机电工程研究所,北京100074

出　　处：《机械工程学报》2014年第8期174-181,共8页Journal of Mechanical Engineering

基　　金：国家自然科学基金资助项目(50979004;51239005)

摘　　要：为研究热力学效应对空化水动力脉动特性的影响,采用试验的方法研究温度为279 K、298 K和318 K时绕水翼的非定常空化流动特性。试验在闭式水洞中进行,采用高速摄影的方法观察不同温度下绕水翼的空穴形态,采用测力系统测量水翼受到的升阻力,并对升力信号进行频谱分析,得到水翼升力在非定常空化阶段的频率特征。结果表明,相同空化数条件下,随着温度的升高,平均升阻力系数降低,升力系数波动程度降低;温度对升阻力系数的影响随着空化数的升高而降低。在不同的空化发展阶段下,温度对升力系数影响的规律不同,空化形成和片状空化阶段,温度对升力系数影响较小;云状空化阶段,温度对升力系数影响较大。之所以出现上述规律是因为在同一空化数下,随着温度的升高,空化区域减小;而空化区域越大,温度对空化流动的影响则越大。In order to study the influence of the thermal effect on hydrodynamic characteristics of cavitating flows, the unsteady cavitating flows around a Clark-y hydrofoil under 279 K, 298 K and 318 K conditions are respectively investigated experimentally. Experiments are carried out in a rectangular test section of a cavitation tunnel. A high-speed video camera is used to visualize the unsteady cavitating flow patterns, and the lift and drag coefficients are measured by dynamics force measurement system. The spectral analysis of the measured data is conducted and the spectrum characteristic of the lift force around the hydrofoil is obtained. The results show that when the water temperature is increased, the average values of lift and drag coefficients decrease as well as the lift fluctuation tends to be mild by keeping the caviation number consistent. The influence on the lift and drag coefficients by temperatures becomes weaken with increases of the cavitation number. The fluctuating scale of the lift coefficient is correlated to the unsteady cavity closely. The temperature has little effect on the frequency of lift when it is cavitation inception or sheet. But when cloud cavity appears, the temperature greatly affects on the frequency based on lift. To interpret the conclusions above, it is inferred that when cavitation number is constantl the cavitation region decreases with the increasing of temperature. Moreover, the influence of the temperature is more distinct when the cavitation region is larger.

关 键 词：热力学效应 温度 空化 动力特性 频率 

分 类 号：TV131[水利工程—水力学及河流动力学]