射流孔间距对横流中两孔射流稀释特性的影响

Effect of spacing of nozzles on dilution properties of two tandem jets in cross-flow

为了解射流孔间距对多孔扩散器污水稀释效率的影响,采用计算流体动力学Fluent软件中的realizable k-ε模型,模拟横流中不同射流孔间距条件下两孔射流横向有效流速、射流浓度轨迹线、速度场和浓度场的变化。结果表明,随着射流孔间距的增大,第1个射流对后面射流的遮挡作用减弱,第2个射流前的横向有效流速增大,射流浓度轨迹线的弯曲程度增大;在射流近区,浓度轨迹线与下游距离呈1/2的指数关系,与射流孔间距呈-0.27的指数关系,在射流远区,与下游距离呈1/3的指数关系,与射流孔间距呈-0.18的指数关系。射流孔间距对第1个射流浓度变化影响较小,对第2个射流,射流孔间距越小,污染物浓度沿水流方向衰减速率越快,当距该射流孔超过8倍孔径后,浓度变化趋于一致。

In order to study the effects of the spacing of nozzles on the dilution efficiency of a multi-hole diffuser, the realizable k-ε model of the Computational Fluid Dynamics ( CFD) software Fluent was used to simulate the effective cross-flow velocity, the jet concentration trajectory, the velocity field, and the concentration field of two tandem jets in cross-flow with different spacing. The results show that, as the spacing of nozzles increases, the sheltering effect of the first jet weakens, the effective cross-flow velocity increases, and the degree of curvature of the jet concentration trajectory increases. Near the jet, there is an exponential relationship between the concentration trajectory and the distance downstream of the nozzle with an exponent of 1/2, and an exponential relationship between the concentration trajectory and the spacing of nozzles with an exponent of -0. 27. At more distance from the jet, there is an exponential relationship between the concentration trajectory and the distance downstream of the nozzle with an exponent of 1/3, and an exponential relationship between the concentration trajectory and the spacing of nozzles with an exponent of -0. 18. The spacing of jets has little influence on the concentration of the first jet. However, the concentration of the second jet decays faster in the direction of flow when the spacing of nozzles decreases, and the concentration grows more stable when the distance from the nozzle is greater than eight times the nozzle diameter.