Publication: An investigation into the influence of material properties on the performance of savonius turbines in hydrokinetic applications
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Date
2023-09-01
Authors
Mohamed Shamsuddin, Muhamad Syukri
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Abstract
Savonius hydrokinetic turbines (HKT) are practical for off-grid power generation due to their simplicity, self-starting capability, and low-speed requirement.
Although the impact of turbine material selection on durability has been established, there is still limited research on its influence on the turbine’s power performance. Therefore, this research aims to investigate the effect of different material properties on the performance of a conventional, two-bladed Savonius rotor. The turbine’s performance was evaluated in three key aspects: power performance, self-starting characteristics, and flow structure. Based on the gap found in the literature review, three different material properties were investigated: weight, surface roughness, and stiffness. The study also considered the effect of water absorption as the turbine is developed for hydrokinetic applications. The experiment was conducted at various Reynolds numbers, R3 ranging from 5.22 ×104 to 9.40 ×104. The turbine performance was then compared in wind and water testing using the principle of dynamic flow similarity. Findings from the power performance analysis were then used to rank five different materials using multi-purpose decision-making analysis (MCDM). Results from the wind tunnel testing suggested that the 𝐶pmax increased with increasing R3, with the highest increment (150%) recorded at 5.22 ×104 to 6.27 ×104. The 𝐶pmax was also found to increase with increasing weight, increasing surface roughness, and decreasing stiffness. The highest 𝐶pmax increment was recorded at 220%, 201%, and 30%, respectively. However, the influence of material properties was significantly influenced by the variation in R3, indicating that some materials may be advantageous within specific ranges of flow speed. For water absorption, the 𝐶𝐶𝑃𝑃 performance of all turbines was found to be less affected, despite having deteriorated flexural strength property of up to 62.3%. The MCDM analysis revealed that soft plastic like poly-lactic acid (PLA) would have a higher performance index at R3 ≤ 6.27 ×104. However, at higher R3, i.e., R3 ≥ 7.31 ×104, conventional materials like aluminium (ALU) turbines would outperform the other materials. The outcomes of the current study demonstrated the impact of various material properties on the power performance of the Savonius turbine, emphasizing the significance of the material selection process particularly for power enhancement.