Effect of geometric shapes of chimney weir on discharge coefficient

Abstract

This study numerically investigated the effects of geometric parameters of chimney weirs on the discharge coefficient (C_d). Here, chimney weirs with apex angles 74°, 84°, 94.4°, 106° and 116° at two crest heights were examined. The RNG turbulence model was selected due to its greater accuracy compared to k-ε, k-ω and LES methods for these types of flows. With increasing discharge and crest height, the value of C_d decreases. The effect of constant C_d showed an increase in the percentage of discharge deviation from the discharge values obtained from numerical solution. Based on dimensionless variables such as ratio of water head to the crest height, the ratio of crest length to the crest height, the ratio of the vertical distance between weir crest and the first point where the weir slope changes to the crest height, and the vertex angle of the inverted triangle, non-linear polynomial regression relations were obtained.

Highlights

• A numerical investigation of the discharge coefficient of Chimney weir with different geometry has been done using FLOW-3D software.

• Chimney weirs have high reliability in measuring discharge due to less sensitivity to changes in upstream water depth.

• This investigation improves the design of hydraulic control structures.

• New equation was developed for calculating the discharge coefficient of Chimney weir.

KEYWORDS:

• Chimney Weir
• discharge coefficient
• water head
• turbulence models
• VOF

Disclosure statement

No potential conflict of interest was reported by the author(s).