Sensitivity Analysis of Angle, Length and Brim Height of the Diffuser for the Small Diffuser Augmented Wind Turbin

Abstract

This paper presents the performance of the diffuser augmented wind turbine (DAWT) with the various diffuser shapes using the numerical investigations. DAWT is also a type of wind turbine and the diffuser shapes, the nozzle shapes and the cylindrical shapes are commonly inserted around the horizontal axis wind turbine (HAWT) to become the more efficient wind turbine. The aim of this study is to find the more efficient design of the diffuser for the horizontal axis wind turbine using the numerical investigations. In this research, the converging and diverging diffuser shape is inserted and the airfoil design is calculated by using the Blade Elementary Momentum Theory. The airfoil type NACA 4412 is chosen because it is suitable for the low wind speed area and easy to produce. The turbulent model k-ω is combined with the Navier Stoke equation to solve the 3-dimensional steady flow simulation of the diffuser augmented wind turbine using the Computational Fluid Dynamics (CFD) simulations. The numerical investigation is used to compare and predict the power coefficient of the DAWT with various shapes. The baseline design of the diffuser (L = 170 mm, H = 57 mm and α = 11̊) is firstly investigated. To predict the power coefficient of the various diffuser shapes, the range of the length of the diffuser is (L/D = 0.5 to 1.5), the range of the brim height of the diffuser (H/D = 0.1 to 0.35) and the range of the angle of the diffuser (α = 5̊ to 15̊ ) are also investigated. The parameters of the diffuser shapes are assigned by using the Central Composite Design Face Centered Method. The response surface method is also used to predict the most efficient diffuser design. The performance of the horizontal axis wind turbine, that of the diffuser augmented wind turbine and that of the diffuser augmented wind turbine with various shapes of diffuser are compared. The performance of new diffuser augmented wind turbine (IND_009) is 50% and 55% higher than the baseline diffuser augmented wind turbine and the horizontal axis wind turbine at rated velocity. The flow visualization of the HAWT, DAWTs are also discussed.

Velocity Augmentation Model for an Empty Concentrator-Diffuser-Augmented Wind Turbine and Optimisation of Geometrical Parameters Using Surface Response Methodology

“…However, it was required to support the hierarchy in the model. On the other hand, it is interesting to note that the increase in velocity augmentation ratio with the increase in diffuser length was reported in previous publications [33,36,54,91,93,94].…”

“…Concurrently, the augmentation of velocity for diffusers is significantly influenced by the length of the diffuser and its opening angle [31][32][33][34]. Moreover, adding a flange to the diffuser is thought to further improve velocity augmentation [11,[35][36][37]. While the cylindrical section primarily serves as a housing for the turbine, its throat length is crucial as it can influence airflow, thereby affecting velocity augmentation.…”

“…However, Ref. [36] cautioned against excessive diffuser length, as it may lead to decreased performance due to potential flow instability. The work in [32] highlighted the critical role of throat section length in shrouded wind turbine systems, emphasising its significance in preventing nonuniform velocity distribution before the turbine and potential flow separation behind the rotor, particularly at the diffuser's outlet.…”

Recent Progress in Design and Performance Analysis of Vertical-Axis Wind Turbines—A Comprehensive Review

“…The outcomes of the optimization revealed that compact designs could achieve a 12-14% enhancement in power performance. Maw (2013) [116] conducted a sensitivity analysis of the diffuser's angle, length, and brim height using numerical simulations. The study found that a diffuser length with an aspect ratio of L/D = 1, a brim height ratio of H/D = 0.35, and a converging angle of 10 • can lead to nearly 50% higher performance compared to the baseline diffuser design from their previous research, which resulted in a 25% increase in performance.…”

Single-Factor Analysis of Variance on the Effect of Blade's Number on Rotor Drag-Type Performance

“…The second power is expressed in equations 1 and 2 [21]. Tip Speed Ratio is the ratio of the tangent speed or tangent speed at the tip of the blade or blade tip with the actual fluid velocity, shown in equation 3 [22]. The power coefficient is defined as the ratio between the actual power generated by the rotor blades and the power acting on the fluid, as shown in equation 4 [23].…”