共查询到17条相似文献,搜索用时 187 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
9.
采用商业软件进行数值模拟和水模实验,考察了不同控流装置对南钢四流大方坯连铸机梯形中间包内钢液流动特性的影响,确定出湍流控制器+导流墙+坝的最佳控流方式.结果表明,原型中间包存在较大的死区,且各流间的流动特性差异较大,尤其是近水口的2流、3流存在明显短路流,不仅造成包内钢液温度分布不均匀,也不利于夹杂物的上浮,影响铸坯洁净度.采用优化后的组合控流装置能够显著改善中间包内钢水的流动状态,使钢液在各流间合理分配,并延长了钢水的平均停留时间,提高活塞流体积分率,降低死区体积分率,均衡了各流间的温度分布,有利于促进铸机生产顺行和铸坯质量的提高. 相似文献
10.
为了提高20#碳钢连铸管坯的产品质量,通过对气泡和非金属夹渣的形成机理以及对中间包内钢水流场数值模拟的研究分析,发现中间包的结构与操作对20#钢连铸坯的生产质量具有较大影响,因此,对中间包的结构与操作进行了优化研究,研究结果显示:(1)通过对中间包的结构优化提高了中间包的钢水液面高度,增加了钢水在中间包内的滞留时间,有利于夹杂物和气泡的消除,从而提高了钢水的均匀性;(2)改进钢水流入、流出中间包的操作,能避免钢流与空气的直接接触,减少钢水的二次氧化;(3)连铸钢水过热度的严格控制,有利于减少钢水的二次氧化和对包衬耐火材料的浸蚀,从而起到降低铸坯中非金属夹渣物的效果。采取这些措施后,2#钢连铸坯的质量取得了显著提高,设备寿命明显延长。 相似文献
11.
12.
Hang Seok Choi Tae Seon Park Kenjiro Suzuki 《International Journal of Heat and Mass Transfer》2008,51(17-18):4276-4286
The turbulent mixing characteristics of multiple jet flows in a micro can type combustor are investigated by means of large eddy simulation (LES). The micro combustor can be used for a micro gas turbine which is hybridized with solid oxide fuel cell. Attention is paid for a micro combustor having a circular disk baffle plate with a fuel injection nozzle in the center and oxidant injection holes allocated annularly. Downstream the baffle plate, a complex flow is produced from the interaction of multiple jet flows and study is made for three different configurations of the baffle plates resulting in different mixing pattern. From the results, it is substantiated that the turbulent mixing is promoted by complex flow fields caused by the jet flows and large vortical flow regions in the micro combustor. This is effective to accelerate the slow mixing between fuel and oxidant suffering from low Reynolds number in such a small combustor. In particular, the vortical flow region formed downstream the fuel jet core region plays an important role for rapid mixing coupled with another flow recirculation region. Discussion is made for the instantaneous and time and space averaged flow and passive scalar quantities which show peculiar turbulent flow and mixing characteristics corresponding to the different flow structures for each baffle plate shapes, respectively. 相似文献
13.
14.
Hang Seok Choi 《Numerical Heat Transfer, Part A: Applications》2013,63(3):230-245
The characteristics of heat transfer in confined multiple jet flows of a micro can combustor is investigated by means of large eddy simulation (LES). The micro combustor can be employed for a hybrid system, which consists of a micro gas turbine and a solid oxide fuel cell. In the present study, the focus is brought into heat transfer, which has a great effect on combustion stability as heat loss to the outside of combustor. The study is made for the three cases of different baffle plate configurations with changing the velocity ratio between fuel and oxidant jets. Downstream of the baffle plate, the flow recirculation regions appear and they can affect the enhancement of the turbulent heat transfer to the wall. In particular, the near-wall flow recirculation region formed between the oxidant jet and the combustor wall plays an important role for wall heat transfer. We study the turbulent thermal fields and conjugate heat transfer which show peculiar characteristics corresponding to the three different baffle plate shapes and different velocity ratios. 相似文献
15.
16.
This study presents the numerical predictions on the turbulent fluid flow and heat transfer characteristics for rectangular channel with porous baffles which are arranged on the bottom and top channel walls in a periodically staggered way. The turbulent governing equations are solved by a control volume-based finite difference method with power-law scheme and the k-ε turbulence model associated with wall function to describe the turbulent structure. The velocity and pressure terms of momentum equations are solved by SIMPLE (semi-implicit method for pressure-linked equation) method.The parameters studied include the entrance Reynolds number Re (1×104-5×104), the baffle height (h=10, 20 and 30 mm) and kind of baffles (solid and porous); whereas the baffle spacing S/H are fixed at 1.0 and the working medium is air. The numerical calculations of the flow field indicate that the flow patterns around the porous- and solid-type baffles are entirely different due to different transport phenomena and it significantly influences the local heat transfer coefficient distributions. Relative to the solid-type baffle channel, the porous-type baffle channel has a lower friction factor due to less channel blockage.Concerning the heat transfer effect, both the solid-type and porous-type baffles walls enhanced the heat transfer relative to the smooth channel. It is further found that at the higher baffle height, the level of heat transfer augmentation is nearly the same for the porous-type baffle, the only difference being the Reynolds number dependence. As expected, the centerline-averaged Nusselt number ratio increases with increasing the baffle height because of the flow acceleration. 相似文献
17.
G. Solorio-Díaz A. Ramos-Banderas 《International Journal of Heat and Mass Transfer》2005,48(17):3574-3590
A swirling ladle shroud (SLS) is used to control flow turbulence and to improve flotation of inclusions in a two-strand tundish of a slab caster. To simulate the fluid flow in a swirling flow three turbulence models, k-ε, k-ω and RSM were employed. Using the mixing kinetics of a tracer as well as Particle Image Velocimetry (PIV) determinations it was found that among these three models the model of turbulence RSM predicts with acceptable agreement the velocity fields of swirling flows experimentally measured. The SLS decreases the turbulence of the entering jet and of the complete flow field when it is compared with a conventional ladle shroud. Kinetic energy of fluid is dissipated through recirculating flows in the transversal and horizontal planes of the tundish helping to the flotation of inclusions through buoyancy, drag and inertial forces. The SLS will become in a new generation of flow control devices in continuous casters of steel. 相似文献