Journal of Mechanical Engineering Science and Technology ISSN 2580-0817 

Vol. 4, No. 2, November 2020, pp. 125-134 125 

 DOI: 10.17977/um016v4i22020p125 

Design of Savonius Vertical Axis Wind Turbine for Vehicle 

 Filian Arbiyani*, Fernando Pranata Lasut

Department of Mechanical Engineering, Atma Jaya Catholic University of Indonesia, 

Jl. Jend. Sudirman No.51, Jakarta, 12930, Indonesia 

*Corresponding author: f.arbiyani@atmajaya.ac.id

ABSTRACT 

The use of cellular phones is increasing in society, but due to the limited battery capacity of cell phones, it 

is necessary to charge the battery when travelling in the long distances. The Savonius type wind turbine has 

a potential as an energy source harvesting the wind energy flowing around the car. However, due to the 

available space on the car, careful design of Savonius vertical axis wind turbine for vehicle is necessary. 

The research is conducted numerically using MATLAB software. The wind speed, Reynolds number, and 

electric power output are numerically simulated to obtain the swept area design. Innovative PLA material in 

the design is also investigated by simulating the effect of mass inertia moment to the design. This design of 

Savonius vertical axis wind turbine for vehicle is expected to charge maximum four cell phone batteries 

with the total electrical output of 60 W. The optimum swept area design of Savonius vertical axis wind 

turbine for vehicle is 0.150 m2 using 3 fins, PLA filament material, with an overlap of 5.3 cm, and a diameter 

for each blade 22 cm according to the overlap ratio used of 0.242. This Savonius vertical axis wind turbine 

design is feasible as an energy source for vehicle owing to its compact design, innovative material used in 

the design, and providing the electric power demand in the vehicle. 

Copyright © 2020. Journal of Mechanical Engineering Science and Technology. 

All rights reserved. 

Keywords: MATLAB, savonius, vehicle mounted wind turbine, vertical axis wind turbine, wind turbine.

I. Introduction

In the digital era, electronics devices are highly used, including a cell phone or smart

phone as a basic need for distance communication. Cell phones use battery as an energy 

source and it always must be recharged. Cell phones or smart phones becomes a basic need, 

and everyone always bring their smartphones while travelling, including while travelling by 

vehicle, such as a car. Travelling in the long journey sometimes need the smartphones to be 

recharged. 

There are numerous kinds of renewable energy. One of them is a wind energy. 

Travelling by vehicle, such as a car, has an enormous potency of a wind energy.   Therefore, 

by implementing a Savonius vertical axis wind turbine on a vehicle, one can harvest this 

energy resources. 

A Savonius vertical axis wind turbine operates using the drag force, and the highest 

drag force can be attained by placing the wind turbine on top of the car cabin [1]. A Savonius 

vertical axis wind turbine takes advantage from the car velocity to gain the maximum wind 

force, which then connected to the power generator. 

In general, to obtain the maximum electric power output, the swept area of wind turbine 

has to be designed as big as possible. However, there is a limit space of the car cabin rooftop 



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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

while implementing the Savonius vertical axis wind turbine on a vehicle. The maximum 

swept area is 0.25 m2 with the ratio of height (H) and diameter (D) is 1:1. The maximum 

swept area is determined based on the shortest length of the common vehicle, while the 

height and diameter are determined based on the Regulation from Ministry of Transportation 

Republic of Indonesia. The length is 0.922 m from the size of rooftop pick-up vehicle 

Daihatsu Granmax [2], and the height and diameter size are 0.98 m [3]. Further safety 

consideration is also applied by implementing half size from the maximum available space 

in the design, i.e. 0.5 m for the height and diameter, thus the design for maximum swept area 

is 0.25 m2. 

Based on the available maximum swept area, careful design of a Savonius vertical axis 

wind turbine is conducted numerically using MATLAB software. The wind speed, Reynolds 

number, and electric power output are numerically simulated to obtain the optimum swept 

area design. Innovative PLA material in the design is also investigated by simulating the 

effect of mass inertia moment to the design.  

II. Material and Methods

There are four parameters used to determine the design of Savonius vertical axis wind

turbine for vehicle, i.e. car velocity which also represents the wind speed, Reynolds number, 

electric power output, and mass inertia moment. The study was conducted numerically using 

MATLAB software. 

A. Car/Vehicle Velocity (U)

The car velocity values were range from 40 km/hour to 80 km/hour. These values are

allowable car speed in a highway or express way. In aerodynamic, a car velocity would be 

assumed as a representative of a wind speed. Therefore, this parameter would determine the 

swept area design according to Eq. (1). 

𝑃𝑤 =
1

2
×𝜌×𝐴×𝑈3 (W)   ..............................…………………………………........... (1)

where: 𝑃𝑤  : Wind power (W) 

ρ : Density (kg/m3) 

A : Swept area (m2) 

U : Wind speed (m/s) 

with the air density of 1.293 kg/m3 at air standard condition [4]. 

The swept area design can be seen in Figure 1, and its calculation using Eq. (2).

𝐴 = 𝐻×𝐷 ......................................………………………………………………… (2) 

where: A : Swept area (m2) 

H : Height wind turbine (m) 

D : Diameter (m) 



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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

Fig. 1. Swept area design of Savonius vertical axis wind turbine 

B. Reynolds number (Re)

The air flow at the surface of the wind turbine blade is assumed as an external flow at

flat plate. At this phenomenon, Reynolds number of 5 × 105 and higher will result in 

turbulence flow. 

Reynolds number is simulated using Eq. (3). 

𝑅𝑒 =
𝑈×𝐷

𝑣
  ................…………………………………………………………...…. (3) 

where:  U : Wind speed (m/s) 

 D : Diameter (m) 

 v : Kinematic viscosity (m2/s) 

with the kinematic viscosity of 1.56 × 10-5 m2/s at air standard condition [4]. 

C. Electric Power Output (Pe)

The electric power output of Savonius vertical axis wind turbine (Pe) is a results
process as can be seen in Figure 2. 

Fig. 2. Main component of a wind turbine 

The electric power output (Pe) is obtained using Eq. (4). The generator efficiency (ηg), 

swept area (A), transmission efficiency (ηm), and the wind speed (U) are determined based 

on the various vehicle velocity with the performance coefficient (Cp) of 0.2 [6]. 

𝑃𝑒 = 𝐶𝑝×𝜂𝑚×𝜂𝑔×
1

2
×𝜌×𝐴×𝑈3  (W)  ……………….……………..........…………. (4)

The generator efficiency (ηg) was calculated using Eq. (5)... 

𝜂𝑔 =
𝑋−(0.5)𝑌(1−𝑌)(𝑋2+1)

𝑋
 …………………………………….…………………… (5) 

with X and Y variable were calculated using Eq. (6) and Eq. (7), respectively. 



128  Journal of Mechanical Engineering Science and Technology  ISSN 2580-0817 
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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

𝑌 = 0.05 (
106

𝑃𝑒𝑅
)

0.215

 ………………………………….……....…………………….. (6) 

In this design, the output power of the generator used is 100 W. This generator 

specification was set as the maximum electric power output (PeR). 

𝑋 =
𝑃𝑡

𝑃𝑡𝑅
  ……………………………………………………………………………... (7) 

where:  PeR : Maximum generator electric power (W) 

Pt : Transmission power (W) 

PtR : Maximum transmission power (W) 

Since the wind speed affects the mechanical (transmission) power, thus the ratio of 

Pt/PtR can be assumed as in Eq. (8). 

𝑃𝑡

𝑃𝑡𝑅
=

𝑈

𝑈𝑅
    ……………………………………………...…………………………... (8) 

where:  U : wind speed (m/s) 

UR : wind speed at the maximum power (m/s) 

The transmission power and the generator efficiency affect the electric power output as 

can be seen in Eq. (9). 

𝑃𝑒 = 𝜂𝑔×𝑃𝑡  (W)   …....……………………………………………………………… (9) 

In the transmission section, the transmission efficiency (ηm) can be calculated using Eq. 

(10). 

𝜂𝑚 =
𝑃𝑚−(0.02)𝑞×𝑃𝑚𝑅

𝑃𝑚
= 1 − (0.02)𝑞×

𝑃𝑚𝑅

𝑃𝑚
  …………………...………………… (10) 

where:  Pm : Mechanical power (W) 

PmR : Maximum mechanical power (W) 

q : stage number 

This transmission efficiency (ηm) and the mechanical power (Pm) affect the 

transmission power (Pt) as can be seen in Eq. (11). 

𝑃𝑡 = 𝜂𝑚×𝑃𝑚 (W) ……………...………………………………………………...… (11) 

With the mechanical power (Pm) is calculated using Eq. (12). 

𝑃𝑚 = 𝐶𝑝×𝑃𝑤  (W) ………………………......………………………………...……. (12) 

with performance coefficient (Cp) of 0.2 [6] and wind power (𝑃𝑤) from Eq. (1).

The expected electric power output in this design is 60 W to recharge the four cell phone 

batteries [4]. In the power plant, it is wise to provide the electric power output (Pepf) higher 

than the expected (Pe), thus a power factor (Pf) is applied in this simulation using Eq. (13). 

𝑃𝑓 =
𝑃𝑒

𝑃𝑒𝑝𝑓
  ………………………………………………………………………….. (13) 

Power factor (Pf) of 0.9 is widely used in the electrical distributor company. 

D. Mass Inertia Moment

The mass inertia moment is calculated using Eq. (14).



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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

𝐼 = 𝐽×𝜌𝑎  (kg.m2)      ……………………………………………………………….. (14) 
where:  J : Area inertia moment (m4) 

              ρa : : Density of the area (kg/m2)
The area inertia moment (J) can be calculated using Eq. (15). 

𝐽 =
𝜋×𝑟4

2
(m4)    …………………………………………………………………….. (15) 

where: r : radius (m) 

Density of the area (ρa) is determined using Eq. (16). 

𝜌𝑎 = 𝑙×𝜌 (kg/m2)      ………………………………………………………………. (16) 
where: l : length (m) 

ρ :     Material density (kg/m2) 
In this Savonius vertical axis wind turbine for vehicle design, there are three (3) 

materials for the options, including an innovative PLA filament material produced by 

advanced technology of 3D printer. The material density is shown in Table 1. 

Table 1. Material density 

Material Density (kg/m3) 

Aluminum 6061 [8] 2700 

Low carbon steel AISI 1018 [9] 7870 

PLA Filament [10] 1240 

This mass inertia moment would affect the blades movement of a wind turbine, 

therefore the proper material chosen is necessary in the design. 

Besides the four parameters above, there are another parameter that are also important 

in designing a Savonius vertical axis wind turbine for vehicle. These parameters are the 

overlap (e) and diameter size for each blade (d) as can be seen in Figure 3. 

The optimum overlap ratio (e/d) for Savonius wind turbine is 0.242 [11], and the 

diameter for each blade can be calculated using Eq. (17). 

Fig. 3. Schematic drawing of Savonius wind turbine [11] 



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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

𝐷 = 𝑒 + (2 [𝑑 − 𝑒]) (m) ………………………………………………………… (17) 

where:  D : Total diameter (m) 

d : diameter for each blade (m) 

III. Results and Discussions

A. Effect of Wind Speed to Swept Area Design

The effect of wind speed to the swept area design of Savonius vertical axis wind turbine

for vehicle can be seen in Figure 4. 

Fig. 4. Effect of wind speed to swept area 

As we can see from Figure 4 that the higher wind speed would need smaller swept area. 

The available maximum swept area on vehicle is 0.25 m2. At this area, the required wind 

speed is 52 km/hour which would result in 0.236 m2 of swept area. This wind speed is 

acceptable as smaller than the available maximum swept area and feasible as a car velocity. 

Another feasible wind speed which represents the car velocity is 55 km/hour which resulted 

in 0.197 m2 swept area and 60 km/hour with 0.15 m2 swept area. These three feasible wind 

speeds and its swept area would then be used as variables to simulate other parameters. 

B. Effect of Wind Speed to Reynolds Number

Based on previous simulation, the three feasible wind speeds of 52 km/hour, 55 km/hour

and 60 km/hour would result in 0.236 m2, 0.197 m2, and 0.15 m2 swept area design. These 

three swept areas would then be used to determine Diameter using Eq. (2). Using these 

diameters at various wind speed would affect the Reynolds number as seen in Figure 5. 



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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

Fig. 5. Effect of wind speed to Reynolds Number 

Larger swept area design would rapidly increase the Reynolds number until it reaches 

the turbulence at Reynolds number of 5 × 105. Higher Reynolds number would affect to 

higher performance coefficient (Cp), thus increasing the electric power output [12]. 

However, this turbulence might cause the chaotic flow which then would change the wind 

direction and might break the wind blades for single wind direction. Therefore, the optimum 

swept area design to prevent this turbulence is 0.15 m2. 

C. Effect of Wind Speed to Electric Power Output

The swept area design from the feasible three wind speed simulation would be used as

variables to simulate the electric power output. The results of wind speed effect to electric 

power output can be seen in Figure 6. 

Fig. 6. Effect of wind speed to electric power output 



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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

Higher wind speed with larger swept area design would result in higher electric power 

output. At the same wind speed, swept area of 0.236 m2 would reach the expected electric 

power output faster. 

D. Effect of Swept Area Design to Mass Inertia Moment

Using the density of each material in this design and the radius of the wind blade, the

mass inertia moment was obtained as seen in Figure 7. 

Fig. 7 Effect of swept area design to mass inertia moment 

The larger blade radius would result in higher mass inertia moment. This would obstruct 

the blades movement. Therefore, smaller mass inertia moment would be recommended as a 

wind turbine material. PLA filament with 0.150 m2 swept area has smallest mass inertia 

moment. 

Based on the four parameters investigated, it was found that the suitable swept area 

design is 0.236 m2 and 0.150 m2, as seen in Table 2. 

Table 2. Parameters matrix of design Savonius vertical axis wind turbine for vehicle 

Swept Area 

(m2) 
Wind Speed 

Reynolds 

Number 

Electric Power 

Output 

Mass Inertia 

Moment 

0.236 √ √ 

0.197 

0.150 √ √ 

Both swept areas have fulfilled the most required parameters. Finally, swept area design 

of 0.150 m2 was selected considering the safety application on vehicle and the capability of 

3D printer while using PLA filament as the material. 

Furthermore, using Eq. (17), the diameter size for each blade is 22 cm and 5.3 cm for 

the overlap. Additional features of 3 fin were also recommended in the design [13]. The final 

design of Savonius vertical axis wind turbine on a vehicle was summarized in Table 3 with 

its implementation on truck model vehicle as shown in Figure 8. 



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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

Table 3. Design of Savonius vertical axis wind turbine on a vehicle 

Design Size 

Swept Area (m2) 

Rasio H:D 

Total Height (cm) 

Total Diameter (cm) 

Material and Mass Inertia Moment (kg/m2) 

Fin 

Overlap Ratio 

Overlap (cm) 

Diameter for each blade (cm) 

0.150 

1:1 

38.81 

38.81 

Filament PLA; 0.959
3 [13] 

0.242 [11] 

5.3 

22 

Fig. 8 Design of Savonius vertical axis wind turbine for vehicle

IV. Conclusions

The optimum swept area design of Savonius vertical axis wind turbine for vehicle is

0.150 m2 using 3 fins, PLA filament material, with an overlap of 5.3 cm, and a diameter for 

each blade 22 cm according to the overlap ratio used of 0.242. This Savonius vertical axis 

wind turbine design is feasible as an energy source for vehicle owing to its compact design, 

innovative material used in the design, and providing the electric power demand in the 

vehicle. 



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Arbiyani & Lasut (Design of Savonius Vertical Axis Wind Turbine for Vehicle) 

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