EFFECT OF 3D INCLINATION ANGLES ON DISCHARGE COEFFICIENT FOR WATER FLOW THROUGH REGULAR POLYGONAL MULTI-ORIFICE EXITS

Abdelrahman, Ahmed Mahmoud; Elmolla, Anas Mohamed; Mobasher, Amir Mohamed

doi:10.21608/auej.2025.354398.1760

EFFECT OF 3D INCLINATION ANGLES ON DISCHARGE COEFFICIENT FOR WATER FLOW THROUGH REGULAR POLYGONAL MULTI-ORIFICE EXITS

Articles in Press

Document Type : Original Article

Authors

¹ Irrigation and Hydraulic Department, Canadian International College (CIC).

² Civil Engineering Department, Faculty of Engineering, Al-Azhar University, Egypt.

³ Civil Engineering Department, Faculty of Engineering, Galala University, Egypt.

⁴ Civil Engineering Department, Faculty of Engineering, Madina Higher Institute

10.21608/auej.2025.354398.1760

Abstract

The discharge coefficient (Cd) is a fundamental parameter in multi-orifice flow, critical for hydraulic systems and flow control applications. This study examines how three-dimensional inclination angles affect Cd for water flow through multi-orifice exits. Using Buckingham's π-Theorem, we conducted dimensional analysis to identify key dimensionless parameters influencing Cd. We performed both experimental tests and computational fluid dynamics (CFD) simulations to evaluate how geometric parameters including inclination angles of multi-orifices in the flow direction and perpendicular to it impact performance. The analysis included five orifice shapes: circular, triangular, square, pentagonal, and hexagonal, with numerical extensions exploring additional polygonal configurations.
Results show that the discharge coefficient exhibits distinct patterns under two rotation conditions. When rotated about the flow direction axis, Cd oscillates periodically, decreasing to 94% of its original value with a 6% amplitude. These systematic variations are influenced by both the rotation angle θ1 and the number of polygon sides (m). When rotated about the perpendicular axis by angle θ2, Cd oscillates consistently across all tested geometries, decreasing to 92% of its original value with an 8% amplitude. The measured Cd values range from 0.635 to 0.716. These findings establish quantitative relationships between geometric orientation and discharge efficiency in multi-orifice systems.

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