Transient Flow Through Combined Pressurized and Open Channel Systems Case Study ‘Conveyor 800 in Lebanon’
"The purpose of this study is to investigate and evaluate the performance of flow in
combined irrigation systems consisting of tunnels and canals designed to operate under
pressurized and free surface flow regimes. The case under study in this thesis is Conveyor
800 in Lebanon, which consists of the open channel of Qelia Canal and pressurized sections
of both Yohmor Tunnel and siphons. Simulation of flow in these structures, under both
steady and unsteady state conditions, required the development of three and one dimensional
hydraulic models involving Computational Fluid Dynamics (CFD) and HEC-RAS software.
The regulating structures in this case study were controlled by PID, an advanced algorithm
developed and integrated in HEC-RAS tools to permit the software to simulate PID control.
Additional two critical parameters acting as constraints were added to the PID. These
parameters are the minimum gate opening and minimum gate correction. The results of the
simulations showed that the PID algorithm in the numerical model controlled the gates
successfully. However, the results also showed that overtopping would occur at the
emergency spillway when emergency shutdown scenarios occurred. Accordingly,
recommendations were provided in order to avoid cavitation and abrasion and optimize the
design of the project."
Omar Rashid Ramadan
Dr. Issam Awad