Experimental and numerical study on the performance and flow pattern of different Savonius hydrokinetic turbines with varying duct angle

  • Aditya Kumar Nag
  • Shibayan SarkarEmail author
Research Article


In this study, three different types of Savonius rotors viz. Savonius hydrokinetic turbine (SHKT), modified Savonius hydrokinetic turbine (MSHKT) and helical Savonius hydrokinetic turbine (HSHKT) are compared based on the performance. The analysis is done experimentally as well as numerically, where experimental domain ceases. Performance of rotors is also evaluated with and without applying duct as an augmentation technique in the flow channel. Experimentally, MSHKT and HSHKT produce 2.74% and 9.04% more energy than SHKT for 1 ± 0.2 m/s. Uncertainties in TSR, Cp and Ct of rotor are 3.05%, 4.39% and 5.35% for the experiment. It is found that HSHKT has better performance than others. Whereas, with duct, performance of HSHKT improves 48.08% more energy than SHKT. The insight of the hydrodynamic behavior considering wake formation, flow separation and vortex formation of the stream flow surrounding to the rotor is also explained using velocity contour, velocity vector and pressure plot. Inlet velocity of 1 ± 0.2 m/s increases by 27.5%, 28%, 29%, 32% and 34%, respectively, for duct angle 20°, 23°, 26°, 29° and 32°. Simultaneously, low-pressure zone increases which leads to extend the formation of the vortex far from rotor and helps to generate higher Cp for HSHKT as 28.63%, 16.16%, 43.01%, 50.13% and 82.32%, respectively.


Savonius hydrokinetic turbine Vortex ANSYS-CFX Duct Performance parameter Flow characteristics 

List of symbols


Overlap distance (m)


Projected area of the rotor (m2)

a1,a2, a3an

Power coefficients of variables


Cross-sectional area of the flow


Aspect ratio


Rotor diameter (m)


Characteristic diameter (m)


End plate diameter (m)


Diameter of the rope (m)


Shaft diameter (m)


Froude number


Acceleration due to gravity (= 9.81 m/s2)


Rotor height (m)


Height of the flowing water (m)


Number of rotation of rotor per minute (RPM)


Blade shape factor


Shaft power (W)


Wetted perimeter of the rotor (m)


Radius of the rotor (m)


Characteristics radius (m)


Reynolds number


Radius of the pulley (m)


Blade thickness (t)


Torque (Nm)


End plate thickness (m)


Top width of the channel (m)


Components of velocity in the corresponding direction (m/s)

ux, uy, uw

Fluctuation of the velocity in the x, y and z-direction respectively (m/s)


Free stream velocity (m/s)


Upstream velocity of the flume (m/s)


Downstream velocity of the flume (m/s)


Width of the channel (m)


Tension in slack side (kg)


Tension in tight side (kg)

X1, X2, X3Xn

Independent sensitive coefficients


Rotor twist angle


Density of the fluid (= 1000 kg/m3)


Angular velocity of the rotor (rad/s)

ω1, ω2, ω3ωn

Uncertainties in the independent variables



Authors would like to acknowledge the authority of IIT (ISM), Dhanbad, Jharkhand, India for carryout this study. Authors would like to acknowledge Science and Engineering Research Board (SERB), Govt. of India for funding the Project File No. YSS/2015/001259 to carry out the research work.


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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringIndian Institute of Technology (ISM)DhanbadIndia

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