Fluid Flow Phenomenon i n a Three - Bladed Power - Generating Archimedes Screw Turbine

Abstract

Experimental studies of the Archimedes screw turbine are applied as a micro hydro power plant for low head focused on the fluid flow. Fluid flow on a screw turbine is not completely filled water flow there is still a free surface between the water fluid and atmospheric air. Except the screw geometry, the turbine screw free surface allows the flow phenomena that are important in the process of turbine screw power generation. The Archimedes screw turbine main driving force is the fluid-gravity weight, which is affected by the inflow depth, inflow velocity and the turbine shaft's slope. The dimensionless parameter Froude number (Fr) is connected to analyze the screw turbine efficiency. The purpose of this study is to figure out the fluid flow role when power generated by a three blades Archimedes screw turbine observed visualized, and also observed the turbine rotation and torque. The observed parameters are varied in inflow depth as the characteristic length (y) of Froude Number, inflow velocity (co), and the turbine shaft slope (α). The screw turbine model, were made under a laboratory scale and made from acrylic material. The geometric form is the three bladed screws which have seven screw respectively, the number of helix turns is 21, the angle of screw blade is 30°, radius ratio of 0.54 with a pitch distance of 2,4 Ro. The result from this study revealed a phenomenon of fluid flow between the screw blades a whirlpool wave occurs or vortex due to the linear momentum in a form of the hydrostatic force against the blade screw which occurs in two opposite directions and the effect of the turbine shaft angular momentum. The vortex would affect the screw turbine power generation process as most of the kinetic energy that goes into the screw turbine sucked into the vortex between the screw blades, but this phenomenon can be reduced by reducing the turbine shaft slope. The highest turbine efficiency of 89% occurred in the turbine shaft's slope of 25° and a flow rate of 0.5 m/s and a 1Ro characteristic length and a 0,12 Froude number.

A Study of The Developing Archimedes Screw as A Turbine

“…The physical phenomenon in the AST has not yet become a concern, whereas this is important to know the hydraulic behavior. Based on this, Saroinsong et al, [28] examined the effect of the vortex on the performance of AST. Based on the results, the vortex affects the performance of this turbine [28].…”

“…Based on this, Saroinsong et al, [28] examined the effect of the vortex on the performance of AST. Based on the results, the vortex affects the performance of this turbine [28]. Furthermore, since the water in the bucket formed a vortex due to shaft rotation, the vortex inhibits shaft rotation [28].…”

“…Furthermore, since the water in the bucket formed a vortex due to shaft rotation, the vortex inhibits shaft rotation [28]. Therefore, reducing the α angle can lessen the vortex [28].…”

Impact of the Minimum Head on Low-Head Hydropower Plants Energy Production and Profitability

“…The efficiency of water energy conversion into mechanical energy received on the shaft is estimated at 80%, and the tendency increases together with increasing turbine diameter [31]. However, the studies in [32] give the highest efficiency value at 89%. The authors quote 4 m as the largest possible Archimedes screw diameter.…”

Characteristics Analysis of the Archimedes Screw Turbine Micro-hydro Power Plant with Variation of Turbine Elevation Angle

“…Several studies on the characteristics of Archimedes screw turbines on various factors have also been carried out. Some examples are the effects of the level of filling water (fluid) [14], the flow of water (fluid) passing through the turbine [15], and the slope and the number of turbine blades [16] on the characteristics and performance of the turbine.…”