Large Blades Research Articles

Fault Diagnosis Method for Imbalanced Samples of Blade Fracture in Large Petrochemical Fan

Abstract The mechanism analysis of the sudden change in load inertia caused by the failure of large petrochemical fan blades is unclear, which makes it difficult to diagnose imbalanced samples faults based on data-driven methods and has the problem of poor interpretability. Based on this issue, a fault diagnosis method for imbalanced samples of broken blades in large petrochemical fan under sudden changes in load inertia is proposed. This method firstly establishes a failure mechanism model for large petrochemical fan blades, revealing the physical characteristics between inertia, torque and speed under sudden changes in load inertia. Secondly, based on the failure mechanism model, the fault characteristics of broken blades in petrochemical fan are extracted to solve the problem of difficult feature extraction of fault samples in imbalanced samples. Finally, a data-driven diagnostic model was constructed under the constraint of sudden changes in load inertia to improve the interpretability of fault diagnosis for large petrochemical fan with broken blades. The experiment shows that the proposed method significantly improves the diagnostic accuracy and effectiveness for detecting faults in broken blades of petrochemical fans, achieving a fault diagnosis accuracy of 99.03%.

Study on Bearing Mechanism of Steel Screw Pile

In order to study the bearing mechanism of a steel screw pile (SSP), a 3D-FEM of “SSP-stratum” was established based on the large-scale general finite element analysis platform ABAQUS. Secondly, the real friction coefficient between pile and soil was determined by comparing it with the field bearing test data of screw piles. Finally, the bearing mechanism and failure criterion of the SSP was revealed. The research showed that the pile-soil friction coefficient was about 0.6 under the condition of this stratum, and the screw pile was in the elastic working stage under the conditions of compression and tension load, which had a large bearing reserve. The magnitude of Young’s modulus was inversely correlated with the settlement value and the extreme value of principal stress. The increase in the Young’s modulus of the stratum was helpful in improving the bearing capacity of the screw pile. The compressive capacity of circular steel tube + screw pile (CST + SP) was about 2 times higher than CST, and the compressive capacity of circular steel tube + large blade + screw pile (CST + LB + SP) was about 2.4 times higher than CST. The tensile capacity of CST + SP was about 3.4 times higher than CST, and the tensile capacity of CST + LB + SP was about 4.9 times higher than CST. The arrangement of large blades better bore the load of the screw part and optimized the stress distribution of the structure. Based on the mechanical analysis in the vertical direction, the bearing mechanism of the SSP under compression and tension conditions was elaborated. The bearing failure criterion of the SSP was summarized from the aspects of mechanics and displacement. The bearing design of the SSP should meet the control of mechanics and deformation at the same time. The research work could provide a useful reference for the design and construction of SSPs.

Design and analysis of hundred-meter wind turbine blade trailing edge based on finite element method (FEM)

Abstract The trailing edge region of composite wind turbine blades usually has a large deformation under wind load and the accidents caused by the damage of blade trailing edge accounts for a large proportion among blade accidents. With the development of large blade size, higher requirements are put forward for the stability of wind turbine blade trailing edge. Therefore, the trailing edge region is critical in the design of blade. A detailed study of the design and analysis for wind turbine blade trailing edge region was carried out in which the structure stability was regarded as the key. The influence of auxiliary spar cap and auxiliary spar web on the stiffness distribution and stability of the trailing edge were studied based on focus and finite element method (FEM). The respiratory effect of different structures due to deformation were analyzed and compared. The results showed that the structure of the auxiliary spar cap and auxiliary spar web can significantly increase stiffness, stability and decrease respiratory deformation at the trailing edge of blade compared to the traditional three webs structure. The structure of auxiliary spar and auxiliary spar web is the best design scheme for hundred-meter composite blade trailing edge.

Optimization and Regulation Method for Large Blade-regulating Pump Stations Considering Safety Constraints

Abstract In plain areas, making flood control and drought resistance a heavy task. Large water pumping stations undertake the important task of water lifting and scheduling. Due to the physical characteristics of large pumping stations, they are often affected by the upstream and downstream water levels during water lifting scheduling, resulting in low head operating conditions. Low head operating conditions can easily cause pumping stations to operate at excessive power, thereby affecting the health of pumping station equipment. Based on the head efficiency curve of a large blade regulating pump station in this article, by optimizing the regulating mathematical model and considering constraints such as water level, flow rate, power, efficiency, and blade angle adjustment time interval under low head conditions, a dynamic programming calculation method is adopted to construct an optimized regulating method for the pump station. Based on real-time water level, various operating data of the unit are optimized to ensure the blade angle, power, and the flow rate and other parameters are all within the safety constraint range. And various operating data could be used to guiding the real-time optimization and adjustment of the pumping station, and additionally providing the operating foundation for the intelligent pumping station.

Enhancing wind turbine load response tool through geometric non-linearities correction: Case study on DEFlex and design load comparison

This paper introduces a rapid correction technique applied in DEFlex, Ørsted’s in-house aero-servo-hydro-elastic solver for offshore wind turbines. The technique addresses geometric non-linearities from large wind turbine blade deflections, focusing specifically on correcting the angle of attack for torsional deflections. To assess the implementation, comparisons were made with the literature and HAWC2, using the IEA 15-MW wind turbine blade subjected to static and simplified dynamic loading. Additionally, simulations of normal operation scenarios, both with and without turbulence, were performed on a real wind turbine exceeding 10 MW rated power. The results were compared with Siemens Gamesa Renewable Energys tool BHawC, which utilizes a co-rotational formulation for capturing large blade deflections. The findings reveal that coupling DEFlex with the correction method accurately captures the angle of attack dynamics and significantly improves the agreement of fatigue loads.

Aerodynamics of a three-dimensionally deformed rigid wing

A flexible wing with a large aspect ratio emerges in many modern engineering applications (e.g. solar planes and super large wind turbine blades) and its interaction with incident flow differs markedly from conventional fluid–structure interactions (FSI), exhibiting frequently a large three-dimensional (3D) deformation. Yet, there is little information on how such deformation may change wing aerodynamics. This work investigates the aerodynamic performance of deformed and cantilever-supported NACA0012 rigid wings with an aspect ratio of 9, using ANSYS Fluent with the SST-κ-ω turbulence model at a chord-length-based Reynolds number Rec of 1.5 × 105. Numerical simulation is validated experimentally. The wing tip bending displacement is up to 4.14c, and the maximum twisted angle is up to 7°. The angle α of attack varies from 0° to 20° at mid span of the wing. It has been found that the torsional deformation can significantly advance the local flow separation, reattachment, bubble length, and transition from laminar to turbulence, resulting in a drop in the critical angle αcr of attack, at which the separation bubble size reaches the maximum. Accordingly, the lift and drag coefficients increase, as well as the bending and pitching-up moments, though the stall is advanced due to a change in local α. The tip vortex is also enhanced, inducing strong downwash postponing the separation bubble on the wing and resulting in redistributed force near the wing tip that increases markedly the local bending moment but decrease the local pitching-up moment. On the other hand, the bending deformation tends to produce an effect opposite to the torsion on the flow structure and causing little change in the lift coefficient, though reducing the induced drag and moments appreciably. With both deformations in place, the torsion overwhelms the bending in general in terms of its impact upon aerodynamics and flow structures, the latter acting to cancel at least partially the effect of the former.

Flint tools in Iron Age burials of Tel Erani: Interpretations in the light of mortuary practices

The current study focuses on large geometric flint sickle blades found in association with the deceased unearthed during the excavation of the Iron Age cemetery of Tel Erani. The archaeological meaning and interpretation of such a correlation are examined here through the prism of the system of burials and beliefs of Iron Age communities in the southern Levant and previous periods, where sickles and sickle blades were found in funerary contexts. Flint tools in the southern Levant may be divided into belonging to the deceased and used in life, and those serving as offerings to the dead by the community. The presence of sickles and flint sickle blades in burials of the southern Levant from the Chalcolithic period to the Iron Age may be interpreted as part of a ritual symbolizing a relationship between the deceased and agriculture. A concluding interpretation of these findings is presented here based on anthropological and archaeological parallels.

Increased Productivity in the Superfinishing of Large Gas-Turbine Engine Blades

Increased Productivity in the Superfinishing of Large Gas-Turbine Engine Blades

Continuum approach of nonlinear dynamic analysis of a rotating wind turbine blade considering hub motion

This paper reports the nonlinear dynamics of a large wind turbine blade considering the hub motion. The investigation is based on a continuum mathematical model, which is derived using the extended Hamilton principle. The proposed model is validated via comparison with both published results and numerical simulations obtained from open source software. The steady state amplitude curves as well as the dominating frequencies of the modal forces are compared and analyzed with discussions on the effects of the hub motion amplitude, yaw angle and rotational frequency of the blade. Comparison of dominant frequencies of modal forces shows that the skewed inflow can strengthen the periodic excitation whose frequency equals to the rotating frequency of the blade. The steady state amplitude curves show that vibration of the edge-wise mode is more significant than that of the flap-wise mode when under the hub motion excitation. Moreover, internal resonance between the first three modes is also observed. The skewed inflow has a significant effect on the first mode in terms of vibration amplitude and the most unfavorable direction of hub motion. Finally, recommendation on how to avoid the resonance and internal resonance of the blades under skewed inflow are given.

A Study on Alloy Characterizations for Long Term Service Based Effects on Materials

Materials are a core part of the development in mechanical turbines, where there is always potential for life-improvement. The demand for alloys with durability, low cost, and long service cycles are evergreen. The materials used in turbomachinery must have excellent resistance to thermal fatigue, as well as high temperature oxidation and corrosion resistance. Good creep resistance is also an important consideration, especially for large blades and multi-airfoil latter stage nozzles. Development of new alloy compositions and material characterization plays a critical role in advanced machinery evolution. In this work, some of the available characterization methods are applied to analyze and study the effect of heat treatment, service effect and aging on alloys.

Higher-order moment stability of large wind turbine blades under stochastic perturbations

Higher-order moment stability of large wind turbine blades under stochastic perturbations

The Petiole of the Miriti Palm: A sustainable material for wind turbine blades?

The Miriti Palm (Mauritia flexuosa) grows abundantly in the Amazon Region of Brazil. The petiole (PMP) that supports the leaves, has a density of about one-half of Balsa wood (BW), which is used in the manufacture of wind turbine blades. A further possible advantage of PMP is that harvesting does not kill the palm tree, in contrast to the harvesting of BW. Because the mechanical properties of PMP have not been measured, we determined the shear and tensile properties of 16 samples of PMP and BW to allow a preliminary assessment of PMP as a possible material for blades. The absolute shear and tensile strengths for BW are higher, but specific properties (normalized by the density) are similar and can favour PMP. Direct substitution of BW by PMP would reduce the weight of a typical large blade by around 2%.

Nonlinear dynamic analysis of parked large wind turbine blade considering parametric excitation

In this study, the nonlinear dynamics of parked large wind turbine blades are investigated, with a focus on the consideration of parametric excitations induced by the combined effect of wind and support motion. A continuum mathematical model for the blade is adopted. The time-varying damping terms that may induce parametric excitation are derived in this study. Nonlinear dynamic responses of NREL 5-MW wind turbine blade are numerically investigated using the multiple-scale method. Results show that the primary resonance of the first flapwise mode can induce the super-harmonic resonance of the first edgewise mode, with considering parametric excitation. Notably, when the ratio between the first flapwise to first edgewise modal eigenfrequencies is tuned to 1:2, the super-harmonic resonance leads to internal resonance between the two modes. In this case, the effects of incident wind speed, excitation direction and amplitude on the blade response are discussed. Quasi-periodic motions can also be induced because of the Neimark-Snack bifurcation in the case of large excitation amplitude.

Accumulation characteristics of precipitation static on rotating wind turbine blades and its influence on the lightning attachment characteristics

AbstractThe linear velocity at the tip of large wind turbine blades can reach 100 m/s, generating static electricity through friction with airborne particles. However, the accumulation characteristics of precipitation static on the blade surface and its impact on the lightning attachment characteristics are rarely reported. The authors constructed a platform for measuring charges on rotating wind turbine blades and employed the electrostatic probe method to obtain the accumulation characteristics of surface charges under different environmental conditions. The experimental results show that positive charges accumulate on the blade surfaces, peaking at 0.69 μC/m2 under experimental conditions. The charge density is positively correlated with airborne particle concentration and blade rotation speed, while it is negatively correlated with relative air humidity. Additionally, the authors developed a model of the electric field distribution on wind turbine blades considering the effects of precipitation static. Simulation results indicate that the electrostatic field induced by precipitation static weakens the field strength in the vicinity of receptors, reaching a minimum of only 38% of the original strength, thereby increasing the probability of lightning protection failure. The findings provide an effective supplement to the lightning attachment mechanism of rotating wind turbine blades.

A probabilistic fatigue life assessment method for wind turbine blade based on Bayesian GPR with the effects of pitch angle

AbstractThe fatigue behavior of large wind turbine blades is complex and stochastic due to their complex structure and operating environment. This paper focuses on developing a probabilistic fatigue life assessment method for wind turbine blades considering the uncertainties from wind velocity, material mechanical properties, pitch angle, and layer thickness. To improve the efficiency of stochastic fatigue behavior analysis of wind turbine blade, unidirectional fluid‐structure coupling (UFSC) and bidirectional fluid‐structure coupling (BFSC) analysis are employed to analyze the stochastic response. Then, Gaussian process regression (GPR) and Bayesian updating are combined to establish the stochastic fatigue behavior prediction model for wind turbine blade. On this basis, a modified S‐N curve formulation is proposed, and the fatigue life of wind turbine blade is analyzed by the modified S‐N curve and compared with the three‐parameter Weibull model. The results indicate that the proposed method for fatigue life assessment has better accuracy. The proposed probabilistic fatigue life assessment method with high accuracy and high efficiency, which is beneficial for the fatigue reliability design of wind turbine blades.

Arslantepe in the foreground: The economic and social role of the large blades at the end of the 4th millennium BC

This paper focuses on the study of large blade assemblages made from chert raw materials at the site of Arslantepe VI-A period (3500–3200 BCE). By applying an analytical approach combining raw material characterization (NM-PCI protocol), technological and use-wear analyses, and experimental archaeology, we discuss our results from a double perspective. At first glance, we demonstrate the great potential that this proxy offers for the reconstruction of technical systems and routine activities in late prehistoric sites. Secondly, we highlight the contribution of large blades for understanding socio-economic dynamics in case-oriented debates. Specifically, large chert blade study provides further pieces of the puzzle to characterize technical and economic behaviors of the social group settled on the mound of Arslantepe at the end of the 4th millennium BC. At this time, a palatine complex with centralized administration and symbols of power, were tools to boost social inequality.

Durability Test of Microtome Blades with the High-Precision Tissue-Sectioning Machine

In this study, the durability of microtome blades, used for sectioning paraffin blocks, was evaluated with the goal of improving the quality of sections in pathology tests. First, for the durability test of microtome blades, a sectioning test device that realizes stable sectioning operations was developed. This device comprised precise stages supported by cross-roller guides, achieving sufficient rigidness. This device allowed automated repetitive sectioning and simultaneously measured the principal and thrust cutting forces. Samples embedding porcine kidney and rib tissues were used for the durability test. Two types of blades with different blade edge angles were used. Additionally, the rake face and cross-section of blades, as well as H&E-stained sections, were observed. In the durability test with porcine kidney tissue, good quality sections were obtained even after 100 times of sectioning with both microtome blades, showing sufficient durability. However, in sectioning porcine rib tissue, the microtome blade with a large blade edge angle produced good-quality sections in the initial phase of the durability test; however, defects such as overlapping of folds were observed after 100 times of sectioning. Meanwhile, the microtome blade with a small blade edge angle experienced blade damage from the early phase of the durability test, resulting in the production of unsuitable preparations for pathology tests. These results indicated that the microtome blade with a small blade edge angle lacked durability against hard tissues such as porcine ribs.

Controlling the structure formation of heat-resistant nickel-based alloys, when manufacturing large gas turbine blades

Controlling the structure formation of heat-resistant nickel-based alloys, when manufacturing large gas turbine blades

Characterization and Prediction of Wind Turbine Blade Damage Based on Fiber Grating Sensor

INTRODUCTION: As a renewable and clean use of energy, wind power generation has a very important role in the new energy generation industry. For the many parts of various wind turbines, the safety and reliability of wind turbine blades are very important. OBJECTIVES: The energy spectrum simulation algorithm included in the wavelet analysis method is used to simulate and analyzewind turbine blade damage, to verify the correctness and validity of wind turbine blade damage analysis. METHODS: Matlab simulation is used to introduce the experiments related to the static and dynamic detection of fiber grating sensors, analyze the signal characteristics of the wind turbine blade when it is damaged by the impact, and provide a basis for the analysis of the external damage of large wind turbine blade. RESULTS: The main results obtained in this paper are the following. By analyzing the decomposition of wavelet packets, the gradient change of wavelet impact energy spectrum before and after the wavelet damage was obtained and compared with the histogram, and the impact energy spectrum of each three-dimensional wavelet energy packet in the image was compared and analyzed, which can well realize the recognition of wavelet damage gradient for solid composite materials. CONCLUSION: With the help of Matlab simulation to collect the impact response signal, using the wavelet packet energy spectrum method to analyze the signal, can derive the characteristics of wind turbine blade damage.

Experimental Studies for the Creation of Composite Materials with Increased Static Mechanical Characteristics

The aim of the study was to experimentally verify the enhancement of certain mechanical properties of a composite material consisting of unsaturated polyester matrix reinforced with fiberglass, by incorporating specific proportions of sodium aluminosilicate (SAS) powders and talc as fillers for the fabrication of large wind turbine blades. Samples composed of these materials, with varying combinations of the added components, underwent testing for tensile and bending strength, and experiments were conducted to determine their modulus of elasticity. The findings indicate that the inclusion of SAS in the matrix material resulted in increased values of tensile strength and modulus of elasticity up to certain proportions. Solely adding talc to the matrix material led to a rise in bending strength. Increasing the talc percentage in the matrix material reinforced with 20% fiberglass resulted in decreased tensile strength and elastic modulus of the samples, while incorporating a blend of SAS and talc into the matrix material reinforced with 20% fiberglass significantly boosted the elastic modulus and tensile strength of the samples under tensile conditions.