Turbulent Flow Characteristics and Dynamics Response of a Vertical-Axis Spiral Rotor

Abstract

Abstract:The concept of a vertical-axis spiral wind rotor is proposed and implemented in the interest of adapting it to air flows from all directions and improving the rotor's performance. A comparative study is performed between the proposed rotor and conventional Savonius rotor. Turbulent flow features near the rotor blades are simulated with Spalart-Allmaras turbulence model. The torque coefficient of the proposed rotor is satisfactory in terms of its magnitude and variation through the rotational cycle. Along the height of the rotor, distinct spatial turbulent flow patterns vary with the upstream air velocity. Subsequent experiments involving a disk generator gives an in-depth understanding of the dynamic response of the proposed rotor under different operation conditions. The optimal tip-speed ratio of the spiral rotor is 0.4-0.5, as is shown in both simulation and experiment. Under normal and relative-motion flow conditions, and within the range of upstream air velocity from 1 to 12 m/s, the output voltage of the generator was monitored and statistically analyzed. It was found that normal air velocity fluctuations lead to a non-synchronous correspondence between upstream air velocity and output voltage. In contrast, the spiral rotor's performance when operating from the back of a moving truck was significantly different to its performance under the natural conditions.

Implementation of a highway wind power generation using vertical axis wind turbine to automatically power a street lamp

“…The results indicate the torque performance of spiral Savonius turbine is better when whole rotation cycle is considered. A stable operation of a turbine is related to maximum torque coefficient and a comparative study between a conventional and spiral Savonius turbine available in (Kang et al, 2013) indicates the maximum torque coefficient of spiral rotor is larger than the conventional rotor of Savonius turbine. A review of fluid dynamics of different rotor designs including spiral Savonius turbine available in (Kang et al, 2014).…”

Aerodynamic study of a Savonius type vertical axis wind turbine for different axial positions between the blades

“…The construction and the aerodynamic profiles of the blades rotor having a significant effect on the efficiency and power of the wind turbines. Several research and works have been carried out in recent years which have led to very useful and important developments to improve the efficiency of vertical axis wind turbines despite the Betz limit [1][2][3][4][5]. Ebrahimpour et al [6] investigated the effect of the central axial and radial position of the blades to the performance of the vertical axis wind turbine by the numerical study by using a realizable K-ε model.…”

Three-dimensional Numerical Study of the Performance of a Small Combined Savonius-Darrieus Vertical Wind Turbine

“…Moreover, adding extra stages, which are angled the blades of the first stage, can reduce the fluctuation of torque without significant loss of the performance [10]. Similar to multi-stage Savonius wind turbines, using helical blades can produce more uniform torque [11,12]. In the case of Darrieus turbines, the shape of airfoils has a significant impact on the overall performance and the self-starting characteristics of the turbine.…”