共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Profiles of the rate of dissipation of turbulent kinetic energy were inferred from temperature microstructure measurements near a bubble plume at the center of a tank with diameter of 13.7 m and maximum depth of 8.3 m. Six sets of between 18 and 51 profiles were collected at airflow rates of 0.1–0.6 L/s, measured at atmospheric pressure, and ensemble-averaged dissipation profiles were calculated. The dissipation in all cases was between 10?8 and 10?6?m2/s3 in most of the profile, but it increased sharply near the water surface. Energy considerations are used to discuss the experimental results in terms of previous numerical models of bubble plume turbulence. Two previous numerical studies show that the turbulence dissipates between 15 and 30% of the available power. In the experiments, the fraction is less than 1% because some of the energy of the plume is used to generate waves on the water surface and the profiles used to compute the volume-averaged dissipation were relatively far from the bubble plume. 相似文献
3.
4.
5.
6.
四机四流大方坯连铸中间包结构优化 总被引:1,自引:0,他引:1
通过水模拟实验,研究了鞍钢一炼钢大方坯连铸4机4流不同结构的中间包的流体流动特性。研究的结果表明,原结构的中间包同一侧的两流之间的流体流动特性存在很大差异,与内侧流相比,外侧流的最小停留时间、峰值时间和活塞体积分率小,死区体积大。采用优化后的湍流控制器及导流坝组合的中间包控流装置,外侧流和内侧流的停留时间分布曲线趋于一致,表明外侧流和内侧流之间的流动特性相接近。中间包结构优化后,平均夹杂物去除率由51.25%提高到73.46%,铸坯中夹杂物的粒度绝大部分小于10μm。 相似文献
7.
8.
通过水模型实验和数值模拟,研究了不同湍流控制器下两流非对称中间包内流体流动特性。数值模拟结果表明:湍流控制器几何结构对两流非对称中间包流体流动特性有明显影响。圆形湍流控制器内流场涡心靠近底部,出口处流体流速垂直向上;中间包流场涡心靠近长水口,涡心高度与挡墙高度基本同高,中间包表面波动大,容易发生卷渣现象。不对称长方形湍流控制器底部为不对称波浪形,流场涡心靠近出口,流体以一定角度从湍流控制器出口流出;其右侧出口面积大于左侧,水口右侧流体流量大于左侧;由于增大了出口面积,出口处流体速度减小,中间包表面平稳。水模型结果表明采用不对称湍流控制器中间包两流之间的平均停留时间差比圆形湍流控制器中间包减少1/4,算术平均值增加5.3%,说明非对称湍流控制器增强了中间包去除夹杂物能力且能有效缩小两流之间流体流动的差异。 相似文献
9.
10.
Water Modeling of Optimizing Tundish Flow Field 总被引:2,自引:1,他引:2
In the water modeling experiments, three cases were considered, ie, a bare tundish, a tundish equipped with a turbulence inhibitor, and a rectangular tundish equipped with weirs (dams) and a turbulence inhibitor. Comparing the RTD curves, inclusion separation, and the result of the streamline experiment, it can be found that the tundish equipped with weirs (dams) and a turbulence inhibitor has a great effect on the flow field and the inclusion separation when compared with the sole use or no use of the turbulent inhibitor or weirs (dams). In addition, the enlargement of the distance between the weir and dam will result in a better effect when the tundish equipped with weirs (dam) and a turbulence inhibitor was used. 相似文献
11.
薄板坯连铸中间包内抑湍器的模拟研究 总被引:3,自引:0,他引:3
控制中间包内钢液的合理流动对夹杂物的排除有重要影响,为此建立了模拟薄板坯连铸中间包流动情况的水模型。通过测定停留时间分布(RTD)曲线,研究了不同组合控流装置对中间包流体流动特性的影响。结果表明,结构及尺寸合理的抑湍器能延长水口响应时间及平均停留时间、提高活塞流区体积分数及降低死区体积分数;抑湍器与单坝组合的控流装置在控制流体流动方面效果极佳,而抑湍器与单墙单坝、单墙双坝组合的控流装置的控流效果不太理想。 相似文献
12.
13.
14.
15.
Vertical array data recorded during the 1995 Kobe earthquake are used to calculate the upward and downward energy flow based on one-dimensional SH-wave multireflection theory, from which the energy dissipation in a surface layer is evaluated as their residual. The dissipated energy thus evaluated in a liquefied site is found to reach about 70% of the upward input energy, which indicates that soil nonlinearity and liquefaction serve as effective energy absorbers. In contrast, more energy returns to deeper ground in sites without strong nonlinear behavior. Furthermore, the dissipated energy in the surface layer tends to increase nonlinearly in a convex shape with increasing equivalent damping ratio of the soil there. A simplified two-layer system indicates that the energy dissipation is influenced not only by the soil damping in the surface layer but also by the impedance ratio between the base and surface layers and the input frequency. The same convex relationship is also obtained in the two-layer system, indicating that the simplified system may reflect some important aspects of the energy dissipation mechanisms in the ground. 相似文献
16.
采用水力学数学模拟的方法,研究了3号多孔挡墙和U挡墙对昆钢小方坯连铸中间包流动特性的影响。水力学模拟依据相似原理,用"刺激—响应"实验方法,测定不同工况下停留时间分布(RTD)曲线,得到两种挡墙对中间包流体流动的影响。然后用数学模拟的方法验证水力学模拟的合理性。研究结果表明:3号多孔挡墙可以延长1号、2号水口响应时间及平均停留时间,缩短了3号水口响应时间及平均停留时间,控制各流流动趋于一致。中间包内流体流动特性得到明显改善。使用U挡墙后,钢液的平均停留时间Ta有了大幅增加,但各水口的初次响应时间差距较大,各流的流动特征一致性较差。因而,3号多孔挡墙控流效果优于U挡墙。 相似文献
17.
18.
19.
通过工业试验研究了中间包内安装石灰过滤器后钢液中夹杂物的行为。工业试验表明,采用石灰过滤器后,钢中夹杂物平均降低20%。在此基础上建立了中间包安装过滤器后钢中夹杂物的去除模型。模型计算结果与试验值基本符合。 相似文献