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The aim of this study is to characterize the steady and unsteady flows of a high‐speed axial fan stage and assess its aerodynamic performance parameters. The flow unsteadiness is related to the stator‐rotor interaction originated mainly by two mechanisms: the first is attributed to the potential effect and the second to the wake‐blade interaction and the mixing through the blades' passages. Such effects are dependent on the circumferential positions of blades and inter‐distance between stator and rotor, which could be alleviated by understanding these flow interactions. The pressure waves' main diametrical modes (two blades interacting with two vanes) and their sequences are predicted analytically. FFT analysis of the computed static pressure fluctuations at different monitor points allowed identifying the prevailing modes of interaction and their frequencies and sequence. The assessment of inter‐distance is an important step toward identifying the detrimental effects of axial interdistance on the aerodynamic performance. The closer the blade‐rows of this fan stage can be spaced, the more compact the cooling system of an automotive could be designed. [ABSTRACT FROM AUTHOR]

Wind turbines are an important source of renewable energy. Although the amount of wind turbine installations has known a considerable increase in recent years, technological improvements are still needed to increase their efficiency. An important subject is the presence of vibrations. For instance, ripples can be present in the torque and shaft speed, which can be caused by turbulence of the air flow, resonance or mechanical problems. Furthermore, tower shadow and wind shear are able to cause significant torque oscillations. In literature, a mathematical model of the torque oscillations has been presented for three‐bladed horizontal‐axis upwind turbines. However, it remains unclear what the impact is of these torque oscillations on the shaft speed. When ripples are present in the shaft speed, they affect the back‐electromotive force and electrical power of the generator and could propagate further in the system. Therefore this study investigates whether this effect is large enough to have a considerable impact on the system. The turbine inertia and size are both relevant parameters in this research. However, it will be shown by mathematical proof that the relative amount of shaft speed ripples caused by tower shadow and wind shear is independent of the turbine size. [ABSTRACT FROM AUTHOR]

Wind shear and tower shadow produce a periodic pulse reduction in mechanical torque captured from wind energy resulting in wind energy conversion system (WECS) active power oscillations. In this study, an adaptive neuro‐fuzzy controller for static VAR compensator, used in power networks integrated with WECS, is presented to address the torque oscillation problem. The proposed controller consists of a radial basis function neural network representing a third‐order auto‐regressive and moving average system model and performing the prediction, and a main controller with adaptive neuro‐fuzzy inference system providing the damping signal. A modified two‐area four‐machine power network with WECS integration is applied to validate the proposed implementation, compared with conventional lead/lag compensation. Time‐domain simulations prove that the proposed controller can provide a damping signal to improve the active power oscillation and system dynamic stability, influenced by torque oscillations under WECSs synchronised operating condition. [ABSTRACT FROM AUTHOR]