氢气注入天然气进行管道输送是解决氢气运输成本高的一种有效途径。氢气与天然气快速混合均匀是确保掺氢天然气管道输运安全的保障。由于混合气体通过回流管道回流到混合管，能够与后进入的掺氢天然气继续混合，提高混合均匀性。因此，使用一种回流式掺混器进行氢气和天然气的混合。利用CFD的方法分析了回流管道倾斜角、回流管道管径比和回流管道的数量对回流式掺混器掺混特性的影响。结果表明，回流式掺混器压损低、出口混合均匀度高、回流率大。在回流管道倾斜角、回流管道管径比、回流管道数分别10°、0.5、3时，回流式掺混器达到的效果最好，其压损、混合均匀度达、回流率分别为76 Pa、99.7%和44.5%。研究结果可为掺氢天然气掺混器参数设计和混合性能提供参考。

Hydrogen-injected into natural gas for pipeline transportation is an effective way to solve the high cost of hydrogen transportation. The rapid and uniform mixing of hydrogen and natural gas is an unavoidable problem to ensure the safety of hydrogen-blended natural gas pipeline transportation. Because the mixed gas flows back to the mixing pipe through the reflux pipe, it can continue to mix with the hydrogen-blended natural gas after entering, and improve the mixing uniformity. Therefore, a reflux mixer was used to mix hydrogen and natural gas. The effects of the inclination angle, diameter ratio and number of reflux pipes on the mixing properties of reflux mixers were analyzed by CFD. The results show that the reflux mixer has low pressure loss, high mixing uniformity and high reflux rate. When the inclination angle of reflux pipe, the diameter ratio of reflux pipe and the number of reflux pipe are 10°, 0.5 and 3, the reflux mixer achieves the best effect, and its pressure loss, mixing uniformity and the reflux rate are 76 Pa, 99.7% and 44.5%, respectively. The research results can provide reference for the parameters design and mixing performance of hydrogen-blended natural gas mixer.