Drop manholes are commonly employed to reduce slopes in sewer systems. Diverse particles can enter into these systems and gather in drop manholes where they can chain and clog the outflow. As their residence time in the manhole pool increases, the outlet blockage risk rises. The jet-breaker was used for improving the performance of drop manholes under Regime R2, in which the inlet jet collides with the manhole outlet. However, its effects on residence time were unknown, and its proper dimensions, in this regard, needed to be determined. Therefore, the effects of jet-breaker dimensions and the inlet pipe filling ratio on residence time were experimentally studied in this paper. Results showed residence time significantly reduces when the jet-breaker length and width are 2 and 1.4 times the inlet pipe diameter, respectively; jet-breaker sagitta is zero, jet-breaker angle is zero degrees, and the inlet pipe filling ratio is 80%. Under this optimum condition, residence time decreased 66% in comparison with the control test.

落水人孔通常用于减少下水道系统的坡度。不同的颗粒可以进入这些系统并聚集在落水检修孔中，在那里它们可以链接并堵塞流出物。随着它们在人孔池中停留时间的增加，出口堵塞的风险也会增加。射流破坏器用于改善 R2 下落式人孔的性能，其中入口射流与人孔出口碰撞。然而，它对停留时间的影响是未知的，在这方面，它的适当尺寸需要确定。因此，本文通过实验研究了射流破碎器尺寸和进气管填充率对停留时间的影响。结果表明，当断流器长度和宽度分别为入口管直径的 2 倍和 1.4 倍时，停留时间显着减少；断流器矢向为零，断流器角度为零，进水管填充率为80%。在此最佳条件下，与对照试验相比，停留时间减少了 66%。