Fig. 1 ( a ) Cross section of the helical Bach vertical axis wind turbine and ( b ) 3D model of the helical Bach vertical axis wind turbine with 180 deg helix angle (a) Cross section of the helical Bach vertical axis wind turbine and (b) 3D model of the helical Bach vertical axis wind turbine wi... More

Fig. 2 ( a ) Wooden pattern of the helical Bach VAWT blade and ( b ) the FRP material helical Bach wind turbine blade (a) Wooden pattern of the helical Bach VAWT blade and (b) the FRP material helical Bach wind turbine blade More

Fig. 3 A computational domain for simulating the vertical axis wind turbine A computational domain for simulating the vertical axis wind turbine More

Fig. 4 ( a ) Three-dimensional unstructured mesh in the computational domain, ( b ) view near the rotating domain, and ( c ) zoomed view of boundary layer mesh near the turbine blade (a) Three-dimensional unstructured mesh in the computational domain, (b) view near the rotating domain, and (c) z... More

Fig. 5 Variation of the pressure coefficient ( c p ) over the back surface of advancing and returning blade for different mesh sizes Variation of the pressure coefficient (cp) over the back surface of advancing and returning blade for different mesh sizes More

Fig. 6 ( a ) Helical Bach vertical axis wind turbine in WTRS, Kayathar, India and ( b ) a schematic of helical Bach vertical axis wind turbine test setup (a) Helical Bach vertical axis wind turbine in WTRS, Kayathar, India and (b) a schematic of helical Bach vertical axis wind turbine test setup... More

Fig. 7 Power measurement: ( a ) actual image of electrical connection and ( b ) circuit diagram Power measurement: (a) actual image of electrical connection and (b) circuit diagram More

Fig. 8 Variation of power coefficient ( C p ) for different speed ratios ( λ ) of helical Bach and it is compared with helical Savonius experimental work [ 5 ] for constant D = 1.5 m and H / D = 1 Variation of power coefficient (Cp) for different speed ratios (λ) of helical Bach and it is c... More

Fig. 9 Variation of torque coefficient ( C T ) for different speed ratios ( λ ) of helical Bach and it is compared with helical Savonius experimental work [ 5 ] for constant D = 1.5 m and H / D = 1 Variation of torque coefficient (CT) for different speed ratios (λ) of helical Bach and it is... More

Fig. 10 Variation of static torque coefficient ( C Ts ) at different rotational angles ( θ ) for helical Bach and it is compared with helical Savonius experimental work [ 5 ] and conventional Savonius VAWT and the modified Bach-type turbine [ 1 ] for constant D = 1.5 m and H / D = 1 Variati... More

Fig. 11 Velocity vector at different tip speed ratios: ( a ) λ = 0.2, ( b ) λ = 0.4, ( c ) λ = 0.6, and ( d ) λ = 0.8 Velocity vector at different tip speed ratios: (a) λ = 0.2, (b) λ = 0.4, (c) λ = 0.6, and (d) λ = 0.8 More

Fig. 12 Pressure contour at different tip speed ratios: ( a ) λ = 0.2, ( b ) λ = 0.4, ( c ) λ = 0.6, and ( d ) λ = 0.8 Pressure contour at different tip speed ratios: (a) λ = 0.2, (b) λ = 0.4, (c) λ = 0.6, and (d) λ = 0.8 More

Fig. 1 Experimental testbed facility with daylight-pipe setup: ( a ) test room and ( b ) interior space Experimental testbed facility with daylight-pipe setup: (a) test room and (b) interior space More

Fig. 2 Daylight-pipe and illuminating diffuser: ( a ) light-pipe and ( b ) diffuser Daylight-pipe and illuminating diffuser: (a) light-pipe and (b) diffuser More

Fig. 3 Path followed by beam and diffuse sunlight inside the reflecting tube [ 23 ]: ( a ) beam component and ( b ) diffuse component Path followed by beam and diffuse sunlight inside the reflecting tube [23]: (a) beam component and (b) diffuse component More

Fig. 4 Single reflector inside the hemispherical receiver Single reflector inside the hemispherical receiver More

Fig. 5 Configurations of dual reflector in the hemispherical receiver Configurations of dual reflector in the hemispherical receiver More