Supercritical Flow in 45° Junction Manhole
Publication: Journal of Irrigation and Drainage Engineering
Volume 127, Issue 2
Abstract
The flow in a junction manhole is analyzed using hydraulic modeling and a semiempirical approach. A large number of experiments was conducted to obtain insight in the complex hydraulic features of flows in either one or both of the approach junction branches. Given their significance in applications, in addition to supercritical flow conditions, junction flow with mixed approach flows were also considered. The results include information regarding the main wave structure, with detailed discussions of locations and heights of so-called waves A, B, and C. Further, the swell height at the downstream manhole end was determined and it was found that choking of the supercritical flow structure occurs mainly because of a capacity limit at this outlet. Then, both the minimum and maximum flow limitations were determined. If the discharge is smaller than the minimum discharge, there is a transition from supercritical to subcritical junction flow. If, on the other hand, the discharge is larger than the maximum discharge, supercritical junction flow breaks down and a pressurized two-phase flow is established, which can be responsible for dangerous phenomena such as manhole geysering.
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Information & Authors
Information
Published In
Journal of Irrigation and Drainage Engineering
Volume 127 • Issue 2 • April 2001
Pages: 100 - 108
History
Received: Aug 15, 2000
Published online: Apr 1, 2001
Published in print: Apr 2001
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