Experimental Investigation of Surges in a Stormwater Storage Tunnel

Abstract

Below grade storage tunnels in stormwater systems are usually designed to operate in a free-surface flow regime. However, intense rain events may trigger flow regime transition to pressurized flow, which results in operational problems. To date, little guidance is available as to the considerations necessary to properly design a system undergoing flow regime transition. In this investigation, an experimental apparatus consisting of a 14.3 m long, 94 mm diameter acrylic pipe was used to observe the nature of flows in such conditions. It was noticed that the air near the pipe crown may pressurize and influence the flow dynamics. Qualitative observations regarding the interactions between the air and water phases during the filling events are included in this study. Generally the surge intensity was maximized when a hydraulic bore propagating towards the surge riser just fills the pipe cross-section, and it increased with the pressure head behind the pressurization front. Furthermore, the results indicate that the effects of air phase pressurization should be properly included in numerical simulations if ventilation conditions are limited.

Three-phase bi-layer model for simulating mixed flows

“…The study was conducted on an experimental setup described by (Vasconcelos and Wright 2005). It consists of a 14.3 m long, 94 mm diameter acrylic pipeline, connected at the upstream end to an inflow box of lateral dimensions 0.25 m × 0.25 m, and at the downstream end with a surge riser of 0.19 m diameter.…”

Flow hydraulic characteristics determining the occurrence of either smooth or abrupt sewer pressurization

“…intermittent air-water jets in the atmosphere) Song 1990, 1991), or even severely damage sewers (Hamam andMcCorquodale 1982, Zhou et al 2002a). Despite these potential drawbacks, the phenomenon has not been extensively explored; however, it has been established that intense and frequent pressure oscillations observed in experiments carried out in a variety of conditions are caused by the complex interaction between water flow and air pockets entrapped in pipes and manholes (Hamam and McCorquodale 1982, Zhou et al 2002b, Vasconcelos and Wright 2005. Moreover, various experiments have shown that the amount of entrapped air and the air pocket arrangement inside the water flow depend on the pipe pressurization pattern.…”

1D unified mathematical model for environmental flow applied to steady aerated mixed flows

“…. What is more, air/water interactions may arise, particularly at the transition bore [5], and alter thoroughly the flow regime and its characteristics. On account of the range of applications affected by mixed flows, a good prediction of its features is an industrial necessity.…”