Computational Flow Analysis on a Real Scale Run-of-River Archimedes Screw Turbine with a High Incline Angle

Abstract

The Archimedes screw turbine (AST) is the most sustainable mini-hydropower extraction method that offers number of economic, social, and environmental advantages. Nowadays, many researchers are interested in AST development as it is considered a new technology. Currently, a lot of researchers are conducting experimental testing of the screws, comparing their reliability with computational fluid dynamic (CFD) analyses. Almost all of them are lab-scale testing models that claiming an average 80% efficiency for low pitch angles. In the case of a real site with a small inclination angle, the length of the screw is large enough to cause severe problems, specially related to bending of the screw. Therefore, this research was conducted to analyze the CFD flow field in a real site-scale AST with the maximum possible inclination of 45 degrees. In addition, the design was done without the upper and lower reservoir as it was conceived as a run-of-river flow system. The simulated real scale AST result showed a maximum efficiency of around 82% for a 5.2 m hydraulic head and 0.232 m3/s discharge. Many researchers claim above 80% efficiency for low inclination angle ASTs with reservoirs. This CFD study indicates that even higher inclination angle ASTs can achieve 80% efficiency in run-of-river; real-scale applications.

Systematic Review of Computational Fluid Dynamics Modelling and Simulation Techniques Employed in Vertical Axis Hydrokinetic Turbines

“…The research conducted by Edirisinghe et al, on Archimedes Screw Turbines (AST) represents a sustainable technology for extracting energy from mini hydropower sources. The authors employed CFD in examining the efficiency of the turbine, revealing the potential for 80% efficiency in practical implementations [34].…”

Archimedes Screw Pump Efficiency Based on Three Design Parameters using Computational Fluid Dynamics Software – Ansys CFX

“…According to Abdul, Dr. Binu, and Dr. Jeoju's findings, the behaviour of the efficiency and the torque produced is directly proportional to the mass flow rate [7]. Nagel figured out the theoretical investigation using the graphical method, practical measurements on full-scale plants, and results of model tests have demonstrated that the shaft tube diameter to the external diameter of the screw ratio must be between 0.45 and 0.55 to achieve maximum efficiency and, consequently, optimal deliveries [1,[12][13][14]. Based on field experience and the design and operation of Archimedes screws, it is recommended that the rotating velocity of the screw in revolutions per minute should not exceed 50/D2/3, where D is the cylinder's outer diameter [2].…”

“…Based on field experience and the design and operation of Archimedes screws, it is recommended that the rotating velocity of the screw in revolutions per minute should not exceed 50/D2/3, where D is the cylinder's outer diameter [2]. The buckets would not fill if the screw were twisted too quickly because of turbulence and sloshing, hence will cause the screw to churn the water to the bottom reservoir rather than raise it [2,[13][14][15]. Meanwhile, mild steel is commonly utilized for fabricating pressure vessels as well.…”