Parts Of Blades Research Articles

Information system and model for analyzing blade geometry and solving problems on ensuring quality of aircraft gas-turbine engines

A procedure is presented to improve the technology for producing turbocompressors that makes it possible to increase an aircraft engine’s quality indices by preassembling compressor blades based on the closeness of the geometric characteristics. Preassmbly uses an intelligence system, the essence of which is a model for analyzing and classifying the geometry of a blade’s complicated surface. The paper describes the mathematical model for analyzing and preassembling the blade geometry according to the closeness of the geometric characteristics using clusterization. The model and its software system are tested on a series of profiles of the concave parts of gas-turbine engine compressor blades as a result of measurement with a coordinate-measuring machine.

Isolation and characterization of an improved strain of Porphyra chauhanii (Bangiales, Rhodophyta) with high-temperature resistance

The blades of the wild-type strain of Porphyra chauhanii (PC-WT) were irradiated with 60Co-γ rays and cultured at high temperature (30 °C) for 25 days. The surviving somatic cells of the irradiated blades were isolated enzymatically and were regenerated into whole blades and screened at high temperature. Vigorously growing blades at high temperature were selected and individually proliferated. A genetically homozygous and free-living conchocelis strain of TR-5 was obtained through parthenogenesis. Subsequently, TR-5 was compared with PC-WT for high-temperature resistance, growth, contents of major photosynthetic pigments, and the releasing ability of monospores and conchospores. The results showed that the survival percentage, division, and rhizoid germination of conchospores were not significantly different between TR-5 and PC-WT at 18 and 23 °C; but the survival percentages were 261.2 and 329.3 % higher, the division percentages were 42.8 and 72.6 % higher, and the rhizoid germination percentages were 94.3 and 199.5 % higher in the former than in the latter at 27 and 29 °C, respectively. When F1 gametophytic blades of TR-5 and PC-WT were firstly cultured at 23 °C for 30 days, and then cultured at 18, 23, and 27 °C for another 10 days, the absolute growth rates of TR-5 blades were 4.4, 4.3, and 10.4 times those of PC-WT and the relative growth rates were 1.1, 1.1, and 2.0 times those of PC-WT, respectively. The apical and middle parts of PC-WT blades were disintegrated due to the release of a large number of monospores after culturing for 15 days at 27 °C or 10 days at 29 °C, and only the basal parts of the blades remained intact. On the other hand, TR-5 blades grew rapidly with normal color and shape without releasing monospores and were slightly curled, even after being cultured for an additional 30 days. In addition, the contents of three major photosynthetic pigments (chlorophyll a (Chl. a), phycoerythrin (PE), and phycocyanin (PC)) and the conchospore numbers in TR-5 at a suitable temperature (23 °C) were 66.7, 244.2, 115.7, and 92.0 % higher than those of PC-WT, respectively. Meanwhile, the blades of TR-5 were 23.2 % thinner than those of PC-WT. The results indicated that TR-5 has thinner blade, higher contents of the major photosynthetic pigments, faster growth speed, higher temperature resistance, has larger number of conchospores released, and no monospore release as compared with PC-WT. It therefore has potential to be developed into a new variety suitable for cultivation in the aquaculture areas with high temperature in the coast of South China.

Design of a new dihedral-angle-controlled molecular scissors: A DFT investigation

DFT calculations are employed to investigate the effects of the addition of a photoisomerizable stilbene unit to Aida′s molecular scissors on relative energies, dipole moments, and kinetic stability according to HOMO-LUMO energy gaps and amplitude of the open-close motion of blade moieties. The most obvious finding emerging from this study is the coming into existence of a new pair of molecular scissors operated by two photoswitchable units. Based on photoisomerization of azobenzene and stilbene units, four conformations appear for these new molecular scissors: cis–cis, cis–trans, trans–cis, and trans–trans. The HOMO-LUMO energy gaps promise that all isomers are kinetically stable. The other important finding is that in these new molecular scissors the dihedral angle between the two blade moieties can be controlled and measured through the open-close motion and the blade parts can adopt two middle states in addition to open-close forms.

Damage tolerance and classic fatigue life prediction of a helicopter main rotor blade

Fatigue life of the main rotor blade of a helicopter is investigated from two different approaches. The blade is comprised of many different parts such as spar, skin, abrasive strip, doublers, box beam doublers, etc. and it undergoes complex random load spectra. A finite element analysis is carried out to assess the stress distribution in the blade parts. Then, using the Miner’s rule the fatigue life of the blade is calculated following a classic life estimation method under random loading. At the next step, damage tolerance approach is used for life estimation of the blade. Fatigue crack growth properties and threshold stress intensity range of the spar is obtained based on ASTM E647 test method. Then, crack growth analysis is done using Zencrack software. In order to calculate the length of the smallest growing cracks and their fatigue crack growth life, no crack growth and slow crack growth approaches are used. A comprehensive investigation is carried out on the effect of initial crack length and aspect ratio on growth or no growth of cracks. Comparing the obtained fatigue life from two different approaches, some conclusive results are drawn.

Modeling dynamic stall on wind turbine blades under rotationally augmented flow fields

AbstractThis paper presents an investigation of two well‐known aerodynamic phenomena, rotational augmentation and dynamic stall, together in the inboard parts of wind turbine blades. This analysis is carried out using the following: (1) the National Renewable Energy Laboratory's Unsteady Aerodynamics Experiment Phase VI experimental data, including constant as well as continuously pitching blade conditions during axial operation; (2) data from unsteady delayed detached eddy simulations (DDES) carried out using the Technical University of Denmark's in‐house flow solver Ellipsys3D; and (3) data from a reduced order dynamic stall model that uses rotationally augmented steady‐state polars obtained from steady Phase VI experimental sequences, instead of the traditional two‐dimensional, non‐rotating data. The aim of this work is twofold. First, the blade loads estimated by the DDES simulations are compared with three select cases of the N‐sequence experimental data, which serves as a validation of the DDES method. Results show reasonable agreement between the two data in two out of three cases studied. Second, the dynamic time series of the lift and the moment polars obtained from the experiments are compared with those from the dynamic stall model. This allowed the differences between the stall phenomenon on the inboard parts of harmonically pitching blades on a rotating wind turbine and the classic dynamic stall representation in two‐dimensional flow to be investigated. Results indicated a good qualitative agreement between the model and the experimental data in many cases, which suggests that the current two‐dimensional dynamic stall model as used in blade element momentum‐based aeroelastic codes may provide a reasonably accurate representation of three‐dimensional rotor aerodynamics when used in combination with a robust rotational augmentation model. Copyright © 2015 John Wiley & Sons, Ltd.

Descriptiori of a grass feeding whitefly of the genusTetraleurodes(Hemiptera: Aleyrodidae) from the Indo-Myanmar border

A new species of whitefly, Tetraleurodes champaiensis Dubey sp. nov. (Hemiptera: Aleyrodidae) found infesting Sporobolus heterolepis (Poaceae) in Mizoram (India) is described along with measurements, line drawings and scanning electron microscope images. The species differs from Tetraleurodes thenmozhiae Jesudasan & David in being black in color and have bluntly pointed dorsal setae. The puparia of T. thenmozhiae are white and have capitate dorsal setae. The puparia of the new species were found feeding at the basal parts of central grass blades and almost near the ground level. An identification key to grass feeding Tetraleurodes species is provided. There was no ant attendance.

Acoustic Kinematics of Helicopter BVI Noise

Helicopter blade-vortex interaction (BVI) noise is known as a critical source of noise annoyance from helicopters. A key feature of the noise is that the trace velocities of the sources generated by the BVI process are supersonic, and thus have high radiation efficiency. This further means that noise is generated selectively by only a limited part of the overall interaction. The consequences of this have been studied using a simple cycloidal shed wake model. This allows the whole process to be explicitly described mathematically. The trace velocity can be infinite for both forward and retreating blades. This will generate strong noise radiation in directions which can be simply defined as a function of advance ratio. Analysis shows that many features are functions of rotor disc position only, independent of the number of rotor blades. This offers a helpful simplification. Radiation generates a series of caustics which can be defined by the analysis. Simplified models of the blade-wake interaction show that both the advancing and retreating blade interactions can generate cusps in the noise. Under some conditions these cusps are predicted to continue to the far field in the rotor disc plane, due to a kinematic balance of the change in propagation direction of the basic source vector and the change in the Mach angle of the principal radiation. This gives a two-dimensional decay in sound levels and will give rise to locally intense BVI field. The model also shows areas of the stronger noise fields will be generated in the direction of motion of the interacting blade. A detailed analysis has been undertaken for a four blade rotor at an advance ratio of 0.2. Multiple caustics from successive blade interactions can be identified, some of which have cusps. The analysis shows that the BVI radiation field can have large levels locally and helps to explain why helicopters are often perceived to be noisier than a simple dBA level might suggest. Each part of the rotor disc noise radiation to the far field can be related back to specific positions on the blade and specific parts of the shed wake. This offers the prospect of providing local adjustments to minimize BVI sources under particular conditions. All these results are based on the two dimensional cycloidal model. However it is believed that these effects must be reflected in more complex computer models and in real helicopters.

Adaptive CAD model (re-)construction with THB-splines

Computer Aided Design (CAD) software libraries rely on the tensor-product NURBS model as standard spline technology. However, in applications of industrial complexity, this mathematical model does not provide sufficient flexibility as an effective geometric modeling option. In particular, the multivariate tensor-product construction precludes the design of adaptive spline representations that support local refinements. Consequently, many patches and trimming operations are needed in challenging applications. The investigation of generalizations of tensor-product splines that support adaptive refinement has recently gained significant momentum due to the advent of Isogeometric Analysis (IgA) [2], where adaptivity is needed for performing local refinement in numerical simulations. Moreover, traditional CAD models containing many small (and possibly trimmed) patches are not directly usable for IgA. Truncated hierarchical B-splines (THB-splines) provide the possibility of introducing different levels of resolution in an adaptive framework, while simultaneously preserving the main properties of standard B-splines. We demonstrate that surface fitting schemes based on THB-spline representations may lead to significant improvements for the geometric (re-)construction of critical turbine blade parts. Furthermore, the local THB-spline evaluation in terms of B-spline patches can be properly combined with commercial geometric modeling kernels in order to convert the multilevel spline representation into an equivalent – namely, exact – CAD geometry. This software interface fully integrates the adaptive modeling tool into CAD systems that comply with the current NURBS standard. It also paves the way for the introduction of isogeometric simulations into complex real world applications.

Diffusion mechanisms and microstructure development in pack aluminizing of Ni-based alloys

Despite the large industrial use of pack aluminizing processes for the protection of parts (e.g. cooling channels) of gas turbine blades, systematic studies relating the formation mechanisms and the chemical composition of pack aluminized layers to important process parameters, including the nature of the base alloy and the temperature, are scarce. In this study, 4 different alloys (pure Ni, Ni–20Cr, Inconel 738 and directionally solidified CM247LC) were subjected to a pack aluminizing process at three different temperatures (950°C, 1000°C, 1040°C), using a pack mix containing a fluorine-based activator; the results were compared to those obtained with a chemical vapor deposition (CVD) aluminizing process performed at 1040°C with the same fluorine-based gaseous precursor.The microstructural characterization, performed by SEM+quantitative EDX analysis, XRD and nanoindentation testing, shows that, during the heating stage of the pack aluminizing process, Al is transported to the sample surface at temperatures too low to allow significant simultaneous diffusion of Ni; therefore, a δ-Ni2Al3 outer layer is formed by inward Al diffusion below the alloy surface, and its growth then continues during the isothermal stage as well. As a result, the chosen isothermal treatment temperature does not affect growth mechanisms, although it modifies the overall thickness of the aluminized layer. δ-Ni2Al3 is converted to β-NiAl after a subsequent vacuum heat treatment at 1120°C. In a CVD process, where gaseous precursor are introduced only after attaining the isothermal treatment stage, Al and Ni diffuse simultaneously from the very beginning of the aluminizing process and β-NiAl is directly developed.Less mobile species (heavy atoms, such as W) in the alloy composition hinder all diffusion phenomena, both during pack aluminizing and during subsequent vacuum heat treatment: after aluminizing, precipitates are developed within the δ-Ni2Al3 outer layer and, after vacuum heat treatment, the resulting β-NiAl layer exhibits a compositional gradient.

Ecobonding of Composite Wind Turbine Blade Structural Parts Using Eco-friendly Adhesives

Structural adhesives used to bond composite blade parts have to fulfil sustainability requirements and REACH regulation in addition to quality design requirements in terms of specific stiffness, specific strength, fatigue and weathering characteristics. To appreciate the impacts involved in the bonding process (e.g., harmful substances, amount of VOC emissions, toxic chemicals, carcinogens, odours, ...), designers and users should have more knowledge and better innovation policies on how to integrate health and environmental aspects into the bonding procedures to enable a sustainable production coupled with green manufacturing practices. With this argument as an objective, the aim of the present paper is to innovate and develop a new approach providing high performance of adhesively-bonded composite blade half-shells in terms of Quality-Health-Environment interrelated issues. Alternative solutions leading to new generation of environmentally-friendly adhesives can be achieved through the integration of a new eco-factor, a, into the classical bonding formulations. Further to that, shear stress eco-ratio, , versus adhesive lap ratio, , for different values of a were plotted and some conclusions were drawn.

Path Planning for Detection Robot Climbing on Rotor Blade Surfaces of Wind Turbine Based on Neural Network

Two-feet climbing robot is proposed for rotor blade surface damage detection. The penalty function is designed based on the simulated annealing neural network for waypoints inside blade. According to the derivative of path energy function to time, waypoints are updated and move toward the direction reducing the path energy consisting of length and penalty function. According to the curvature variation range, a novel weighted simulated-annealing-temperature updating method is designed to get comprehensive optimization of the path energy and convergence speed. The path planning is accomplished for the root, middle, and tip blade parts, respectively. The asymptotic analysis of the waypoint coordinating updating process was given, and the updated start point is adopted during escaping from inside. The effect of weight on path energy and convergence speed is analyzed. The planning results show the effectiveness of the proposed path planning algorithm, and the weighted average method is valid for the comprehensive optimization.

Kelp forest as a habitat for mobile epifauna: case study ofCaprella septentrionalisKröyer, 1838 (Amphipoda, Caprellidae) in an Arctic glacial fjord

Distribution and abundance of the amphipod Caprella septentrionalis in relation to environmental conditions and habitat preferences were investigated in a kelp forest in Hornsund, Spitsbergen. Three sampling sites differed in hydrodynamics, organic and inorganic suspension concentration, and sedimentation rates. None of these abiotic factors or species of a macroalgal host appeared to have a significant influence on C. septentrionalis abundance and size range. An apparent preference towards the blade parts of the algal thalli was observed. These results support the idea of C. septentrionalis as a generalist Arcticboreal species that takes advantage of the protective nature of kelp forests. Keywords: Caprellid amphipod; Arctic fjord; kelp forest; population structure; distribution; macroalgae (Published: 20 November 2013) Citation: Polar Research 2013, 32 , 21037, http://dx.doi.org/10.3402/polar.v32i0.21037

T-ray를 이용한 풍력터빈 브레이드 비파괴결함평가

A study of terahertz waves (T-ray) was made for the nondestructive evaluation of FRP (Fiber reinforced plastics) composite materials. The to-be-used systems were time domain spectroscopy (TDS) and continuous wave (CW). The composite materials investigated include both turbine blades of wind energy (non-conducting polymeric composites) and conducting carbon fiber composites. Terahertz signals in the TDS mode resembles that of ultrasound; however, unlike ultrasound, a terahertz pulse was not able to detect a material with conductivity. This was demonstrated in CFRP (Carbon fiber reinforced plastics) laminates. Refractive index (n) was defined as one of mechanical properties; so a method was solved in order solve the n in the material with the cut parts of the turbine blades of wind energy. The defects and anomalies investigated by terahertz radiation were foreign material inclusions and simulated disband. Especially, it is found that the T-ray went through the turbine blade with greater thickness (about 90mm).

Influence of a wind turbine service life on the mechanical properties of the material and the blade

ABSTRACTThis paper presents results out of investigations of the DEBRA‐25 wind turbine blades. Almost unique in the history of modern wind energy, these blades were in operation for 18 years next to a weather station and were investigated afterward. Therefore, the loads experienced in the operational life could be post‐processed accurately with the measured data of the weather station and the turbine. The blades are made of materials that are similar with today's wind turbines. Furthermore, intensive laboratory tests and free field tests have been carried out, and all load assumptions and data and results are still available today. The results include experimental investigations on the moisture content of the load‐carrying material, static and fatigue behavior of the material, the relaxation of the coupling joints, the natural frequencies of the blade and a full scale static blade test. It is shown that the structural performance of the DEBRA‐25 service blades is comparable with modern wind turbine blades. Although some damage was found by visual inspection, the service blade of the DEBRA‐25 showed excellent mechanical behavior in the full scale blade test. Only small changes of the edgewise eigenfrequencies were detected. The pre‐tensioning forces of the IKEA bolts, where the two blade parts are connected, were measured and were still adequate. Copyright © 2012 John Wiley & Sons, Ltd.

Development of Glass-Fabric Composite Wind Turbine Blade

The development process of a glass-fabric composite wind turbine blade is presented. A finite element model is constructed for the design and stress analysis of the wind blade. The wind blade parts were fabricated using the vacuum-bag molding technique. The assembling process of the wind blade is described in detail. The wind blade was tested to validate the suitability of the design. The finite element method is used to predict the failure wind loads of the wind blade.

Resistência à erosão por cavitação de aços inoxidáveis austeníticos CrMnSiN depositados por PTA

A erosão por cavitação deteriora componentes em serviço, tais como partes metálicas de bombas de água, válvulas e, em especial, pás de turbinas hidráulicas, sendo nesse último caso responsável por elevados prejuízos ligados tanto aos custos da manutenção direta, como sobretudo às perdas por interrupção na geração de energia elétrica. Dentre os materiais aplicados no reparo por soldagem de danos por cavitação incluem-se aços inoxidáveis tradicionais tipo AISI 308 e 309, aços inoxidáveis ao Co e ligas à base de Co (stellites), caracterizando-se essas últimas pela maior sensibilidade a trincas, dificuldade de esmerilhamento e pelo mais alto custo. Nesse contexto este trabalho buscou formular, depositar e analisar o desempenho de aços inoxidáveis austeníticos CrMnSiN, soldados pelo processo PTA. A resistência à erosão por cavitação foi avaliada segundo a norma ASTM G 32-92. A microestrutura foi caracterizada por microscopia ótica e microscopia eletrônica de varredura e a formação de martensitas α' e ε, induzida pela cavitação, foi avaliada por difração de raios-X. A integridade da superfície dos depósitos foi controlada por END, além disso a dureza e a facilidade de acabamaneto por esmerilhamento serviram como critérios para avaliar os revestimentos soldados. Verificou-se que os revestimentos aplicados por PTA eram livres de trincas de solidificação, com baixa porosidade, boa molhabilidade e adequado acabamento superficial. A melhor liga inoxidável austenítica elaborada (0,03%C; 0,35% N; 13,2%Cr; 11,8% Mn; 2,8%Si; bal %Fe) mostrou uma resistência à erosão por cavitação próxima aquela das principais ligas comerciais.

311 ジェットエンジン静翼部品VANEのプレスロール圧延実験及び実験条件変更による未充填部分の改善並びにFEM解析(塑性加工とその周辺技術(2),ものづくりにおける基礎研究と先端技術の融合)

311 ジェットエンジン静翼部品VANEのプレスロール圧延実験及び実験条件変更による未充填部分の改善並びにFEM解析(塑性加工とその周辺技術(2),ものづくりにおける基礎研究と先端技術の融合)

KNOX overexpression in transgenic Kohleria (Gesneriaceae) prolongs the activity of proximal leaf blastozones and drastically alters segment fate

KNOX (knotted1-like homeobox) genes have a widely conserved role in the generation of dissected leaves. Ectopic KNOX activity in leaves in various angiosperm lineages causes leaf form changes that can elucidate how the configuration of leaf development evolved. We present an analysis of leaf morphology and morphogenesis in transgenic Kohleria lines overexpressing a heterologous KNOX gene. Kohleria, like many members of Gesneriaceae, has simple-serrated leaves with pinnate venation. KNOX overexpression causes prolonged segment proliferation in proximal, but not distal, parts of leaf blades. Elaborate dissected segments reiterate the zonation of the whole leaf, with organogenic activity persisting between a distal maturation zone and a proximal intercalary elongation zone. The architecture of vascular bundles is severely altered, with a reduced midvein and a more palmate venation. The initial establishment of organogenically competent primordial margins (marginal blastozones) and the onset of tissue differentiation in early stages of leaf development were similar in wild-type and KNOX overexpressing lines. However, leaves overexpressing KNOX often failed to fully mature, and persistent marginal blastozones were found at the base of blades in mature portions of the shoot. We conclude that KNOX-mediated perpetuation of marginal blastozones in Kohleria is sufficient to induce a set of processes that result in highly dissected leaflets, which are unusual in this plant family. Spatial confinement of blastozones between an early maturing tip and a late elongating petiole zone reflects the presence of distinct maturation processes that limit the ability of the leaf margins to respond to ectopic KNOX gene expression.

Metal flow in the precision forging of aluminum alloys

To research impeller parts flow behaviors in the die forging process, the finite element method is used to study the deformation flow behavior of different shapes in the blank forming process. The results show that the blade parts of the forgings were hard to fill, but with the section of the blade shifting down, the metal has a marked trend to flow toward this area of the die cavity. Compared with a cylindrical shape, the die cavity of the blade part can be filled more easily and the uniformity of metal flow will increase. Using a ladder shape to manufacture forgings of impellers can meet requirements for design and properties.

Sandwich Materials for Wind Turbine Blades — Present and Future

Wind turbine blades are being manufactured using polymer matrix composite materials, in a combination of monolithic (single skin) and sandwich composites. Present day designs are mainly based on glass fiber-reinforced composites (GFRP), but for very large blades carbon fiber-reinforced composites are being used increasingly, in addition to GFRP by several manufacturers to reduce the weight. The size of wind turbines have increased significantly over the last 25 years, and this trend is expected to continue in the future. Thus, it is anticipated that wind turbines with a rated power output in the range of 8—10 MW and a rotor diameter about 170—180 m will be developed and installed within the next 10—15 years. The article presents an overview of current day design principles and materials technology applied for wind turbine blades, and it highlights the limitations and important design issues to be addressed for up-scaling of wind turbine blades from the current maximum length in excess of 61 m to blade lengths in the vicinity of 90 m as envisaged for future very large wind turbines. In particular, the article discusses the potential advantages and challenges of applying sandwich type construction to a larger extent than is currently being practiced for the load-carrying parts of wind turbine blades.