Performance and Stress Analysis of Helical Darrieus Hydrokinetic Turbine

This study comprises a performance analysis and stress analysis of the helical Darrieus hydrokinetic turbine (HDHKT), considering the turbine’s solidity by varying the number of blades. Primarily, in order to conduct performance analysis, numerical investigation of three- and four-blade HDHKTs are designed in SOLIDWORKS software and to be evaluated in ANSYS CFX software. Secondly, stress analysis is performed for the selected turbine in ANSYS static structural based on the performance analysis. For this analysis, the cross section of each blade for all the turbines is considered as NACA 4421 as it shows best results due to the optimum blade thickness. For the performance analysis, different operating conditions are considered in which free-stream velocity is considered 0.5 m/s for each number of blades. The obtained results suggest that with an increase in solidity, starting torque increases, corresponding to the operating condition. The highest coefficient of power was obtained at four-blade HDHKT at the solidity of 0.25. Moreover, obtained results from the performance analysis suggest that four-blade HDHKT performance is best. Further, numerical analysis is conducted by selecting four-blade HDHKT for the stress analysis in the ANSYS static structural, considering free-stream velocity 0.5‒2.0 m/s. For the analysis mentioned above, the obtained hydraulic loads from the ANSYS CFX are further subjected to ANSYS static structural domain to obtain the stress values and strength of each HDHKT. The results obtained from the stress analysis suggest that the four-blade HDHKT having solidity of 0.25 shows better results and can sustain hydraulic loads at the desired operating condition. The maximum von-Mises stress values for the varying free-stream velocity 0.5‒2.0 m/s for solidity 0.25 is 26.36 N/mm2, 67.72 N/mm2, and 70.32 N/mm2, respectively. Therefore, four-blade HDHKT having solidity of 0.25 is selected as best performing and capable of bearing hydraulic load.