Iranian Society of Heating, Refrigerating, and Air Conditioning Engineers (IRSHRAE) Journal of Renewable and New Energy 2423-4931 12 1 2025 03 21 Numerical investigation on role of a circular deflector with diagonal splitter blades on performance of savonius turbine Numerical investigation on role of a circular deflector with diagonal splitter blades on performance of savonius turbine 114 123 213575 10.22034/jrenew.2025.213575 FA Seyed Rasoul Hosseini MSc student, Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran. Mohammad Javad Maghrebi Professor, Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran. Journal Article 2023 06 10 One of the most important sources of renewable energy is wind energy. We can harness the kinetic energy of the wind by using wind turbines. One of the fundamental problems with Savonius wind turbines is their low efficiency due to direct wind impact on the returning blade and applying negative torque to it. One new and cost-effective method to increase the efficiency of these turbines is to use a deflector upstream of the flow to prevent wind from hitting the returning blade and producing negative torque. Due to the cylindrical geometry of the deflector, it cannot guide the flow at an arbitrary angle. Additionally, a relatively large vortex region will form downstream of the deflector and near the turbine, which will have undesirable effects on turbine performance. These vortices can be controlled by installing flow splitter blades on the deflector. This study used computational fluid dynamics techniques in a two-dimensional simulation with Ansys Fluent software. Initially, a cylindrical deflector without flow splitter blades was designed and its simulation results were validated with previous experimental research. Then, as an innovation, a splitter blade was installed at a desired angle and directed flow towards the advancing blade of the turbine. The simulation results show that using a deflector with splitter blades at an angle of 5 degrees increases the turbine power coefficient by 23.4% compared to its state without a deflector at a tip speed ratio of 0.6. One of the most important sources of renewable energy is wind energy. We can harness the kinetic energy of the wind by using wind turbines. One of the fundamental problems with Savonius wind turbines is their low efficiency due to direct wind impact on the returning blade and applying negative torque to it. One new and cost-effective method to increase the efficiency of these turbines is to use a deflector upstream of the flow to prevent wind from hitting the returning blade and producing negative torque. Due to the cylindrical geometry of the deflector, it cannot guide the flow at an arbitrary angle. Additionally, a relatively large vortex region will form downstream of the deflector and near the turbine, which will have undesirable effects on turbine performance. These vortices can be controlled by installing flow splitter blades on the deflector. This study used computational fluid dynamics techniques in a two-dimensional simulation with Ansys Fluent software. Initially, a cylindrical deflector without flow splitter blades was designed and its simulation results were validated with previous experimental research. Then, as an innovation, a splitter blade was installed at a desired angle and directed flow towards the advancing blade of the turbine. The simulation results show that using a deflector with splitter blades at an angle of 5 degrees increases the turbine power coefficient by 23.4% compared to its state without a deflector at a tip speed ratio of 0.6. https://www.jrenew.ir/article_213575_9fcfd458894e7d3605a59322cde20e0b.pdf