Experimental study of the Effect of the Blades of Number on Characteristics Pico Bulb Turbine on Horizontal Flow

This study discusses the effect of the number of blades on a horizontal flow propeller turbine performance on a small scale experimentally. The development of small-scale water turbines has made many advances, including water turbines with the horizontal flow. Water turbines in horizontal flow can be applied to irrigation systems, piping systems, the wastewater treatment channel, and other closed channels. Pengukuran dynamic head pada aliran horisontal berdasarkan nilai pressure drop atau perbedaan tekanan sebelum dan sesudah turbin. Dynamic head measurement on the horizontal flow is based on pressure drop values or pressure before and after the turbine. Static bulbs placed before the turbine aim to increase the speed of water flow and potentially improve turbine performance. This study aims to determine the effect of the number of blades on the performance and efficiency of propeller turbines. The blade angle used is 200 with a bulb ratio of 0.6 to the pipe diameter. The variations in the number of blades used were 4, 5, 6, and 7, with each tested at 7 L / s, 9 L / s, 11 L / s, and 13 L / s. The results of this study indicate the number of blades 5 with a discharge of 13 L / s shows the best turbine performance compared to the number of other blades, besides that the number of blades 5 with a flow rate of 13 L / s shows the best efficiency value of around 40%.

Analysis of Bulb Turbine Hydrofoil Cavitation

The influence of a bulb runner blade hydrofoil shape on flow characteristics around the blade was studied. Experimental work was performed on a bulb turbine measuring station and a single hydrofoil in a cavitating tunnel. In the cavitation tunnel, flow visualization was performed on the hydrofoil’s suction side. Cavitation structures were observed for several cavitation numbers. Cavitation was less intense on the modified hydrofoil than on the original hydrofoil, delaying the cavitation onset by several tenths in cavitation number. The results of the visualization in the cavitation tunnel show that modifying the existing hydrofoil design parameters played a key role in reducing the cavitation inception and development, as well as the size of the cavitation structures. A regression model was produced for cavitation cloud length. The results of the regression model show that cavitation length is dependent on Reynolds’s number and the cavitation number. The coefficients of determination for both the existing and modified hydrofoils were reasonably high, with R2 values above 0.95. The results of the cavitation length regression model also confirm that the modified hydrofoil exhibits improved the cavitation properties.