Blade Number Effect for A Horizontal Axis River Current Turbine at A Low Velocity Condition Utilizing A Parametric Study with Mathematical Model of Blade Element Momentum

Abstract

Abstract-The power system using the clean decentralized renewable horizontal axis river current turbine can be an alternative option in delivering locally and sustainably the energies for the communities inaccessible to the electricity connection. One of the important aspects in the technology design is the selection of the blade number. This aspects can raise several consequences including the performance, the manufacturing cost and the construction constrain. The performance must be on the top of the priority in the technology design as the river velocity is typically low which effortlessly brings the technology uneconomically attractive. This study deals with the investigation of effect of the blade number on the performance of the horizontal axis river turbine for low speed condition. The investigation is conducted by a parametric study with the mathematical model of the Blade Element Momentum. The results indicate that turbines with high blade number deliver a better performance than those with the lower blade number. However, the consequences will be the low rotation for the high bladed turbines thus requiring a high gearing ratio for the mechanical transmission. This study also discusses the reason for the results of the investigation and presents a recommendation for designing of the river turbine for such low speed condition in relation to the decision of the blade number.

Open center tidal turbine: How a new mooring system concept affects the performances

“…The gap between the machines' performances induces a couple of considerations. The first one involves the C p : as mentioned in Table 3, for the three blades turbine, it is 0.40, 6 meanwhile, as per Table 4, for the open centre one the C p is 0.45, 17 12.5% higher; secondly, the different flow speed (2.55 vs 2.67 m/s), related to the different installation depth, accounts a further 4.7%, so the whole difference between the turbines performances is about 18%, similar to the energy output (308 vs 362 MWh/year).…”

“…In position 1, the turbine hooks the rod. The new tidal stream, in the opposite direction, allows the rod to rotate so that the turbine is ready to work in the new direction, performing again the above described phases ( Figure 6), positions 6,7,8,9). Further details can be found in.…”

“…Although the environmental impact is still felt considerable and under deep investigation, these technologies achieved a satisfactory level of performance and reliability. ( Peter et all 4 ) investigated new potential sites in Scotland (2004), meanwhile in Reference 6, the authors take in consideration the river purposes. One of the examples of full study on a pilot power plants was published on 2006 by Polagye and Previsic 7 : a feasibility study, starting from site assessment up to the public utility network connection and cost analysis, treated on the performances of seabed tidal turbines, at Knik Arm, Alaska, demonstrating the suitability for small communities, at that time, and sustainability even toward the seasonal ice formation.…”

Performance Evaluation of Axial Flow Wind Turbine Integrated with The Condenser

“…It was due to the blockage effect on ten blades number wind turbines which causes the rotation speed smaller about 27% than a turbine with five blades number. The decreasing in rotational speed causes a decrease in mechanical power produced by the axial flow wind turbine [12]. CP is a ratio between the mechanical power of a turbine and mechanical power contained in the airflow.…”

“…The blade numbers and the blade pitch angles were varied to obtain the maximum Cp and the maximum exhaust air recovery. The reason underlying the variation of the blades number and the blade pitch angles is because the addition of blades number can increase the torque and mechanical power followed by decreasing the value of cut-in speed and increasing starting torque from axial-flow wind turbine, while the change of blade pitch angle will affect the magnitude of drag and lift force generated by the blade so that the greater blade pitch angle, the lower resulting lift force, but the drag force will be even bigger [12][13][14].…”