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<p>The performance of horizontal-axis wind turbines is commonly determined using the momentum-based formulations that predict an ideal upper bound for the power coefficient. However, when the efficiencies of practical turbines are measured, they consistently fall below this theoretical limit due to some irreversible aerodynamic losses. It is purposed in this paper to present an energy-based analysis of wind turbine performance that is founded on the concept of the relative kinetic energy between the rotating blades and the incoming airflow. The energy balance is formulated in terms of the relative stagnation enthalpy and the extractable power is shown to be directly affected by the dissipation mechanisms associated with the viscous drag, the wake rotation, the finite blade effects and turbulence. A realistic power coefficient is then derived by introducing a loss factor that represents the fraction of the relative kinetic energy that is irreversibly degraded during the energy conversion process. The resulting model developed has been shown to remain fully consistent with the classical actuator disk theory thus recovering the Betz limit in the absence of losses. It nonetheless yields some realistic values of the efficiency for practical wind turbines when the effects of dissipation are included. The proposed framework clearly provides a physical interpretation as to why the modern three bladed wind turbines typically achieve peak power coefficients well below the theoretical maximum. It also explains the further reduction that is observed in the small scale machines operating at low Reynolds numbers. The analysis offers a thermodynamic basis that is consistent for the performance prediction and blade aerodynamic optimization under realistic operating conditions. The energy loss model has been implemented on some different blade shapes to obtain values of the real coefficient of performance. The results from the energy loss model have been compared to those obtained from aerodynamics theory for one of the blades and also validated by experimental data. The scheme developed give results infinitely close to the designers C<sub>p</sub> which serves as certificates for wind turbines and thus provide an energetic envelope bounding the performance of realistic, loss-inclusive wind turbine rotors.</p>

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Performance prediction of horizontal axis wind turbines (HAWT) based on both aerodynamics and thermodynamics theories with the incorporation of an energy loss model

  • 期刊论文

  • 发表日期：

    2026年3月12日

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  • D. Afungchui,
  • J. Ebobenow,
  • A. Helali,
  • H. Cheriff,
  • B. Kamoun,
  • C. N. Neba

摘要

The performance of horizontal-axis wind turbines is commonly determined using the momentum-based formulations that predict an ideal upper bound for the power coefficient. However, when the efficiencies of practical turbines are measured, they consistently fall below this theoretical limit due to some irreversible aerodynamic losses. It is purposed in this paper to present an energy-based analysis of wind turbine performance that is founded on the concept of the relative kinetic energy between the rotating blades and the incoming airflow. The energy balance is formulated in terms of the relative stagnation enthalpy and the extractable power is shown to be directly affected by the dissipation mechanisms associated with the viscous drag, the wake rotation, the finite blade effects and turbulence. A realistic power coefficient is then derived by introducing a loss factor that represents the fraction of the relative kinetic energy that is irreversibly degraded during the energy conversion process. The resulting model developed has been shown to remain fully consistent with the classical actuator disk theory thus recovering the Betz limit in the absence of losses. It nonetheless yields some realistic values of the efficiency for practical wind turbines when the effects of dissipation are included. The proposed framework clearly provides a physical interpretation as to why the modern three bladed wind turbines typically achieve peak power coefficients well below the theoretical maximum. It also explains the further reduction that is observed in the small scale machines operating at low Reynolds numbers. The analysis offers a thermodynamic basis that is consistent for the performance prediction and blade aerodynamic optimization under realistic operating conditions. The energy loss model has been implemented on some different blade shapes to obtain values of the real coefficient of performance. The results from the energy loss model have been compared to those obtained from aerodynamics theory for one of the blades and also validated by experimental data. The scheme developed give results infinitely close to the designers Cp which serves as certificates for wind turbines and thus provide an energetic envelope bounding the performance of realistic, loss-inclusive wind turbine rotors.