Experimental approach of free flow to pressurized flow in sewer pipes: upstream to downstream pressurization

ABSTRACT

Sewer pipe pressurization is a phenomenon that can cause structural damage in urban drainage systems and can result in a public health issue, especially in cities that have combined sewer systems. Studies have classified the phenomena of downstream to upstream pressurization in stages, proposing several mathematical models to predict pressure variations and the effect generated by air entrapment. This paper considers the opposite pressurization process, upstream to downstream, caused by a sudden increase in discharge. Using a physical model in which drainage time and flow rate magnitude are controlled, severe flood drainage events are simulated. Results show that the increases of water level are gradual, and when the depth reaches full pipe flow, pressure increases are also gradual without any transients. The contribution of this work relies on concluding that it is highly improbable that the pressurization process in this case could cause damage problems in the drainage infrastructure. The same results were obtained regardless of the rate of increase in flow and the maximum final pressure in the pipe, which differs from the downstream-upstream case. There are no pressure transients.

Keywords:

• Hydraulic models
• laboratory studies
• sewer hydraulics
• sewer pressurization
• water pipelines

Disclosure statement

No potential conflict of interest was reported by the authors.