Document Type : Research Paper

Authors

1 Department of Welding and Fabrication Engineering, Faculty of Engineering, Akwa Ibom State Polytechnic, Ikot Osurua, Ikot Ekpene, Akwa Ibom State, Nigeria.

2 Department of Mechanical Engineering, Faculty of Engineering, Akwa Ibom State Polytechnic, Ikot Osurua, Ikot Ekpene, Nigeria.

10.22105/riej.2022.364299.1341

Abstract

In this paper, the performance characteristics of a fabricated horizontal axis wind turbine with and without flanged diffusers were studied using wind tunnel experiment. Measurements of global parameters (power, torque, rotational speed efficiency, etc.) were carried out at wind speed regime between 3-7 m/s. Flanged diffusers of five different inlet-outlet diameter ratios were employed. The results showed minimum mean increments in tip-speed ratios (TSR) of about 45 % with the smallest diffuser and a maximum of 80 % with the largest diffuser. Increments in the torque even at modest wind speed of 4 m/s were as much as 65, 70 and 76 % for the largest three diffusers and about 33 % for the smaller diffuser. The power output (with and without diffuser) gradually increased from 3-7 m/s wind speed, while the power coefficient (Cp) increased from 3-5.5 m/s, and thereafter began to fluctuate as the wind speed approached 7 m/s. Comparatively, maximum Cp of the turbine without diffuser was 0.22 for λ=0.534 at a wind speed of 7 m/s, while the maximum average value of Cp for turbine with flanged diffuser 3 was 0.34 for λ=0.706 at the same wind speed. As a result of the flanged diffuser attachment, the maximum Cp increased by 36 %. The results showed mean incremental values of 52 and 57 % with the greater value obtained from the second largest diffuser (Di/Do = 0.70) and the least value from the largest diffuser (Di/Do = 0.80), while the first three diffusers achieved near identical increments of 55 %. This consequently implies that increments in the extracted power (i.e., Cp) above 5 m/s wind speed declined with indications of separation and turbulence in the flows beyond the rotor.

Keywords

Main Subjects

  • Aniekan, I. K. P. E., & Ekom, E. T. U. K. (2020). 3 dimensional modelling of the wind flow trajectories and its characteristic effects on horizontal axis wind turbine performance at different wind regimes. Journal of international environmental application and science15(2), 68-80.
  • Aniekan, I. K. P. E., Ekom, E. T. U. K., & NDON, A. I. (2021). Modal analysis of horizontal axis wind turbine rotor blade with distinct configurations under aerodynamic loading cycle. Gazi university journal of science part a: engineering and innovation, 8(1), 81-93.
  • Ikpe, A. E., Etuk, E. M., & Adoh, A. U. (2019). Modelling and analysis of 2-stage planetary gear train for modular horizontal wind turbine application. Journal of applied research on industrial engineering, 6(4), 268-282.
  • Etuk, E. M., Ikpe, A. E., & Adoh, U. A. (2020). Design and analysis of displacement models for modular horizontal wind turbine blade structure. Nigerian journal of technology, 39(1), 121-130.
  • Ekom, E. T. U. K., Emem, I. K. P. E., & Aniekan, I. K. P. E. Computation of aerodynamic load (s) induced stresses on horizontal axis wind turbine rotor blade with distinct configurations. Gazi university journal of science part a: engineering and innovation, 327-338.
  • Shahsavarifard, M., Bibeau, E. L., & Chatoorgoon, V. (2015). Effect of shroud on the performance of horizontal axis hydrokinetic turbines. Ocean engineering, 96, 215-225. https://doi.org/10.1016/j.oceaneng.2014.12.006
  • Abe, K. I., & Ohya, Y. (2004). An investigation of flow fields around flanged diffusers using CFD. Journal of wind engineering and industrial aerodynamics, 92(3-4), 315-330.
  • Nunes, M. M., Junior, A. C. B., & Oliveira, T. F. (2020). Systematic review of diffuser-augmented horizontal-axis turbines. Renewable and sustainable energy reviews, 133, 110075. https://doi.org/10.1016/j.rser.2020.110075
  • Abe, K., Nishida, M., Sakurai, A., Ohya, Y., Kihara, H., Wada, E., & Sato, K. (2005). Experimental and numerical investigations of flow fields behind a small wind turbine with a flanged diffuser. Journal of wind engineering and industrial aerodynamics, 93(12), 951-970.
  • Abe, K., Kihara, H., Sakurai, A., Wada, E., Sato, K., Nishida, M., & Ohya, Y. (2006). An experimental study of tip-vortex structures behind a small wind turbine with a flanged diffuser. Wind & structures, 9(5), 413-417.
  • Ohya, Y., Karasudani, T., Sakurai, A., & Inoue, M. (2006). Development of a high-performance wind turbine equipped with a brimmed diffuser shroud. Transactions of the japan society for aeronautical and space sciences, 49(163), 18-24.
  • Takahashi, S., Hata, Y., Ohya, Y., Karasudani, T., & Uchida, T. (2012). Behavior of the blade tip vortices of a wind turbine equipped with a brimmed-diffuser shroud. Energies, 5(12), 5229-5242.
  • Ohya, Y. (2014). Bluff body flow and vortex—its application to wind turbines. Fluid dynamics research, 46(6), 061423.
  • Matsushima, T., Takagi, S., & Muroyama, S. (2006). Characteristics of a highly efficient propeller type small wind turbine with a diffuser. Renewable energy, 31(9), 1343-1354.
  • Lipian, M., Karczewski, M., & Olasek, K. (2015). Sensitivity study of diffuser angle and brim height parameters for the design of 3 kw diffuser augmented wind turbine. Open engineering, 5(1), 280-286.
  • Schubel, P. J., & Crossley, R. J. (2012). Wind turbine blade design. Energies, 5(9), 3425-3449.
  • Okeniyi, J. O., Moses, I. F., & Okeniyi, E. T. (2015). Wind characteristics and energy potential assessment in Akure, South West Nigeria: econometrics and policy implications. International journal of ambient energy, 36(6), 282-300.