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Wind energy is contributing to more and more portions in the world energy market. However, one deterrent to even greater investment in wind energy is the considerable failure rate of turbines. In particular, large wind turbines are expensive, with less tolerance for system performance degradations, unscheduled system shut downs, and even system damages caused by various malfunctions or faults occurring in system components such as rotor blades, hydraulic systems, generator, electronic control units, electric systems, sensors, and so forth. As a result, there is a high demand to improve the operation reliability, availability, and productivity of wind turbine systems. It is thus paramount to detect and identify any kinds of abnormalities as early as possible, predict potential faults and the remaining useful life of the components, and implement resilient control and management for minimizing performance degradation and economic cost, and avoiding dangerous situations. During the last 20 years, interesting and intensive research results were reported on fault diagnosis, prognosis, and resilient control techniques for wind turbine systems. This paper aims to provide a state-of-the-art overview on the existing fault diagnosis, prognosis, and resilient control methods and techniques for wind turbine systems, with particular attention on the results reported during the last decade. Finally, an overlook on the future development of the fault diagnosis, prognosis, and resilient control techniques for wind turbine systems is presented.

Using conjugate heat transfer methods, the effects of the combination of hole shapes and hole compound angles on the temperature field of actual turbine blades were studied. Four-hole shapes and three-hole compound angles were set on the GE-E3 1st turbine blades. The results show that changes in compound angles have different effects on blade temperature in different hole shapes, exhibiting distinct characteristics. For the cylinder hole configuration, regardless of whether it is the suction surface or the pressure surface, the compound angle of -45° case has the lowest regional average temperature, with a maximum decrease of 18.7 K. In the console hole configuration, the selection of the hole compound angle needs to consider the mainstream velocity components. This is mainly because in the console hole configuration, the coolant velocity is faster, and when the coolant’s spanwise velocity component is aligned with the mainstream, it reduces the lift of the cooling air. For fan-shaped hole configuration, the case with a compound angle of -45° demonstrates the strongest ability to reduce wall temperature on both the suction surface and pressure surface, with a maximum reduction of 52 K. This is primarily because, in the -45° compound angle case, the coolant not only flows out along the hole but also a small portion flows out from the upper part of the hole, resulting in a larger overall coverage area. For the 7-7-7 shaped hole configuration, the overall trend is similar to that of the fan-shaped hole, especially on the pressure surface, where the -45° compound angle case also shows the strongest ability to reduce wall temperature, achieving a reduction of 44.7 K.

Fabricated wind turbine blades have unavoidable deviations from their designs due to imperfections in the manufacturing processes. Model updating is a common approach to enhance model predictions and therefore improve the numerical blade design accuracy compared to the built blade. An updated model can provide a basis for a digital twin of the rotor blade including the manufacturing deviations. Classical optimization algorithms, most often combined with reduced order or surrogate models, represent the state of the art in structural model updating. However, these deterministic methods suffer from high computational costs and a missing probabilistic evaluation. This feasibility study approaches the model updating task by inverting the model through the application of invertible neural networks, which allow for inferring a posterior distribution of the input parameters from given output parameters, without costly optimization or sampling algorithms. In our use case, rotor blade cross sections are updated to match given cross‐sectional parameters. To this end, a sensitivity analysis of the input (material properties or layup locations) and output parameters (such as stiffness and mass matrix entries) first selects relevant features in advance to then set up and train the invertible neural network. The trained network predicts with outstanding accuracy most of the selected cross‐sectional input parameters for different radial positions; that is, the posterior distribution of these parameters shows a narrow width. At the same time, it identifies some parameters that are hard to recover accurately or contain intrinsic ambiguities. Hence, we demonstrate that invertible neural networks are highly capable for structural model updating.

Based on the purpose of studying the impact of bird strike on compressor aerodynamic performance, this paper takes a single-stage low-speed axial flow compressor as an object to establish a blade model damaged by bird strike, and on this basis, it carries out a three-dimensional full-loop numerical simulation and experiments on the compressor model with damaged blades. Through comparison with the experimental data of undamaged compressors, the results show that after the rotor blades are damaged, the rotor blades are damaged. The aerodynamic performance and stability of the compressor have significantly decreased, which accords with our understanding. The reliability of the numerical simulation method is verified by analyzing the detailed flow field structure of typical working conditions and comparing the experimental data of the compressor, which lays a foundation for the relevant calculation of damaged blades in the future.

The hollow thin-walled structure is increasingly used in advanced aero-engine turbine rotor blades, and the traditional surface temperature measurement method based on groove buried couple is no longer applicable. In this paper, a new thermocouple integration method is proposed. The laser additive manufacturing process is used to generate thermocouple embedding channels on the surface of turbine blades. After the thermocouple is embedded, it is pre-fixed, and the thermocouple protection is realized by supersonic flame spraying technology. The strength of the thermocouple integrated structure of the turbine blade is verified by finite element analysis. Based on CFD analysis, the influence of thermocouple integration on the efficiency, pressure ratio and temperature distribution of the turbine blade is studied. The high-speed rotation test shows that the thermocouple integrated structure has high strength and reliability and meets the measurement requirements. This method can provide technical support for the surface temperature measurement of hollow thin-walled turbine rotor blades.

To change the current situation of the seriously redundant design of the creep rupture life of low-cost short-life turbine rotor blades, this paper studies the creep rupture characteristics of the typical low-cost material K424 alloy of the integral casting turbine rotor at multiple high stress levels within the near-plastic and plastic ranges at 700°C. Based on the Larson-Miller equation, a creep rupture life equation is established, and a high-precision bivariate creep constitutive model within the high stress range is developed. Compared with the existing parameter methods, it shows obvious superiority, laying a foundation for the refined design of the creep rupture life of low-cost short-life turbine rotor blades.

This paper presents the development of a multi‐fidelity digital twin structural model (virtual model) of an as‐built wind turbine blade. The goal is to develop and demonstrate an approach to produce an accurate and detailed model of the as‐built blade for use in verifying the performance of the operating two‐bladed, downwind rotor. The digital twin model development methodology, presented herein, involves a novel calibration process to integrate a wide range of information including design specifications, manufacturing information, and structural testing data (modal and static) to produce a multi‐fidelity digital twin structural model: a detailed high‐fidelity model (i.e., 3D finite element analysis [FEA]) and consistent beam‐type models for aeroelastic simulation. A key element is that the multi‐fidelity structural digital twin method follows the rotor from the stages of design, to manufacturing, then to the ground testing and field operation. The result of this comprehensive approach is an accurate multi‐fidelity digital twin structural model for the geometric, structural, and structural dynamic properties of the as‐built blade within a 1% match in mass properties, 3.2% in blade frequencies, and 6% in deflection. The different stages of processing this information within the methodology are discussed. The rotor examined is the SUMR‐Demonstrator (SUMR‐D), which was installed on the Controls Advanced Research Testbed (CART‐2) wind turbine at the National Wind Technology Center. The digital twin model developed here was utilized to design controllers to safely operate SUMR‐D in field tests, which are providing additional data for further evaluation and development of the multi‐fidelity digital twin structural model.

Gas turbines (GTEs) are often utilised in harsh environments where the GT components, including compressor vanes and rotor blades, are subject to erosion damage by sand and dust particles. For instance, in a desert environment, the rate of damage made by solid particles erosion (SPE) becomes severe, and therefore results in degradation to the GTE parts, lowering the cycle efficiency, reducing the device lifetime, and increasing the overall cost of the operation. As such, understanding the erosion mechanism caused by solid particles and the effects associated with it is crucial for selecting the appropriate countermeasures and maintaining the system performance. This review paper provides a survey of the available studies on SPE effects on GTEs and surface protective coatings. Firstly, the ductile and brittle SPE mechanism is presented, as well as the ductile-brittle transition region. Then, an in-depth focus on the parameters associated with the SPE, such as particles properties and impingement conditions, is introduced. Furthermore, the existing theoretical models are shown and discussed. Afterwards, erosion resistant coating materials for surface protection and their selection criteria are covered in the review. Finally, the gap in knowledge and future research direction in the field of SPE on GTEs are provided.

This study employs numerical methods to investigate the film-cooling characteristics of a rotating flat-plate model featuring a single row of film-cooling holes. The model dimensions and rotational speed are based on the first-stage turbine rotor blade of the classic GE-E3 aero-engine. The model incorporates three hole compound angles (−45°, 0°, and 45°) and two coolant intake methods (via the hub port or shroud port of the plenum). The influence of these intake methods on film-cooling effectiveness was comparatively analyzed for each compound angle configuration. For the hole compound angles = 0° case, the shroud intake case consistently achieves higher cooling effectiveness than the hub intake case, with a maximum improvement of 18.7%. This enhancement is primarily attributed to the centrifugal force impeding coolant flow within the plenum chamber during the shroud intake case. Consequently, this flow behavior broadens the spanwise coolant coverage and reduces the coolant jet momentum. For configurations with compound angles (hole compound angles = ±45°), the counter intake case demonstrates higher cooling effectiveness than the in-line intake case under both rotating and stationary conditions, with a maximum difference of approximately 7.78%.

Low Engine Order (LEO) excitations of the last steam turbine rotors generally arise from high unsteady flows due to circulation and reversal caused by low steam exit velocity and non-uniform flow-paths. These low-frequency excitations impose significant constraints on the aero-mechanical design of the Low-Pressure (LP) rotor since they may induce substantial forced response vibration amplitudes leading to High Cycle Fatigue (HCF) failures. Therefore, it is crucial to accurately predict the effects of Low Engine Order forcing to ensure the reliability and durability of the LP blade design. In this work, two different numerical approaches are used and the results compared. The first approach consists of URANS CFD simulations with the outlet distortions coming from diffuser to assess LEO forcing for forced response assessment. The second approach is based on pressure distributions obtained from a frozen rotor full annulus simulation. Forced response analyses are finally performed with an in-house tool based on modal work computations.