Blade Shape Research Articles

Design and Analysis of a 3D Frictional Mechanical Metamaterial for Efficient Energy Dissipation

AbstractThis study introduces a novel frictional mechanical metamaterial composed of a central hexagon or re‐entrant honeycomb frame, a lower section with four tapered columns, and an upper portion with a blade shape. When subjected to an external uniaxial force, the 3D structure of the metamaterial utilizes sliding interactions to dissipate frictional energy. The mechanical properties of the proposed metamaterial, such as load‐displacement relationships, hysteresis area, and peak force, can be fine‐tuned by adjusting geometric parameters and constituent materials. Extensive analysis is conducted through experimental compression tests, finite element (FE) simulations, and theoretical modeling. Comparative assessments of the metamaterial's energy dissipation performance demonstrated a good agreement between experimental and simulation results, with minor variations observed for deeper compression cycles. The proposed metamaterial offers the potential for superior elastic energy absorption and dissipation, making it a promising solution for applications requiring repeated energy dissipation or damping under cyclical loads while maintaining a lightweight profile.

Optimization of the Small Wind Turbine Design—Performance Analysis

In recent decades, the intensive development of renewable energy technology has been observed as a great alternative to conventional energy sources. Solutions aimed at individual customers, which can be used directly in places where electricity is required, are of particular interest. Small wind turbines pose a special challenge because their design must be adapted to environmental conditions, including low wind speed or variability in its direction. The research study presented in this paper considers the energy efficiency of a small wind turbine with a horizontal axis of rotation. Three key design parameters were analyzed: the shape and inclination of the turbine blades and additional confusor–diffuser shape casings. The tests were carried out for three conceptual variants: a confusor before the turbine, a diffuser after the turbine, and a confusor–diffuser combination. Studies have shown that changing the shape of the blade can increase the analyzed wind turbine power by up to 35%, while changing the blade inclination can cause an increase of up to 16% compared to the initial installation position and a 66% increase in power when comparing the extreme inclination of the blades of the tested turbine. The study has shown that to increase the wind speed, the best solution is to use a confusor–diffuser configuration, which, with increased length, can increase the air velocity by up to 21%.

Hydrodynamic properties of propellers with large blade-area ratio and truncated blade in free water

In the literature exist data about the hydrodynamic characteristics of propulsion systems, which include a duct and a fixed-pitch propeller with a truncated blade shape (Kaplan propeller), which has a relatively small blade-area ratio of 0.55. Usual such propellers has a very high loading coefficient, which entails the need to increase propellers blade-area ratio in order to prevent the occurrence of developed cavitation. The article presents the results of the first stage of research, which included testing a series of four-blade truncated propellers with a blade-area ratio 1.0 in free water. The tests were carried out in the towing tank of Admiral Makarov State University of Maritime and Inland Shipping on experimental installation, which include a special hydrodynamic stand. A series of tested propellers were 3D printed from PET-G plastic. A preliminary assessment showed that the chosen diameter of the models will ensure the achievement of supercritical Reynolds numbers at a rotation frequency of about 20 s–1. However, during the tests, it was found that the rotational speed must be increased to 30 s–1, which, in turn, led to a reduction in the test program due to the regime limitations of the experimental equipment. Nevertheless, the analysis of the test results made it possible to build a “hull” and “machinary” diagrams according to the Papmel form. An assessment of the strength of the models was carried out, which showed that the stresses arising in the root of the blade are significantly less than the allowable ones. The obtained results expand the design possibilities of Kaplan propellers with water-jet propulsion units, as well as a part of the “propeller-nozzle” propulsion complex.

Accurate reconstruction of turbine blade point cloud and multiple point cloud registration based on structured light

In recent years, the industry has increasingly adopted vision-guided laser processing techniques to machine cooling holes in turbine blades, placing higher demands on the accuracy of visual measurement. Therefore, to meet the need for high-precision measurement of the three-dimensional shape of turbine blades in the context of laser processing of film cooling holes, this paper proposes a structured light-based method for precise reconstruction of turbine blade point clouds and multi-point cloud registration. Specifically, to improve the accuracy of point cloud reconstruction, an improved phase matching and reconstruction method based on epipolar constraints is proposed. To enhance the accuracy and stability of multi-point cloud registration, a weighted iterative closest point (ICP) method combined with a mark point registration strategy is proposed, optimizing the stability of the ICP algorithm and achieving high-quality multiple point cloud stitching. Experimental results validate the effectiveness and accuracy of the proposed method.

Multi‐criteria hydraulic turbine optimization using a genetic algorithm and trust‐region postprocessing

AbstractA two‐stage, multi‐objective optimization approach is proposed to improve the overall efficiency of the time‐consuming and computationally expensive optimization process for hydraulic turbines. The purpose is to optimize the shape of the turbine blades, designed using 30 parameters, in order to maximize its efficiency and minimize both the cavitation volume and the deviation between the desired and the calculated design head. In the first step of the routine, the genetic algorithm “Non‐Dominated Sorting Genetic Algorithm II (NSGA‐II)” is used to generate an initial approximation of the Pareto front that covers a wide variety of possible solutions, that is, optimal trade‐offs between the conflicting objectives. Subsequently, to ensure convergence, the trust region optimizer “Constrained Multiobjective Problem Optimizer with Model Information to Save Evaluations (CoMPrOMISE)” is used, which is initialized with individuals selected from the Pareto set generated by the genetic algorithm.

A Neutral Polysaccharide from Medicago Sativa L.: Structural Properties and Hypoglycemic Activity In Vitro and In Vivo.

Medicago sativa polysaccharides (MSPs) are beneficial compounds extracted from Medicago sativa L. that exhibit multiple medicinal activities. However, little is known about their hypoglycemic effects. In this study, MSP-II-a, a neutral polysaccharide with an Mw of 4.3×104 Da, was isolated and purified from M. sativa L. Monosaccharide composition analysis determined that MSP-II-a was composed of arabinose, glucose, galactose, mannose, rhamnose, and xylose in a molar ratio of 2.1 : 4.0 : 1.1:0.4 : 1.4 : 1.1. Structural characterization of MSP-II was performed using a combination of methylation analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results showed that MSP-II-a was mainly comprised of 1,4-p-Glc, 1,3,4-Rha, and 1,3-p-Gal glycosidic linkages, revealing a mesh-like texture with irregular blade shapes. In vitro assays demonstrated that MSP-II-a, at concentrations of 200 and 400 μg/mL, promoted glucose uptake in insulin-resistant 3T3-L1 adipocytes. In vivo studies have shown that MSP-II-a significantly alleviates insulin resistance by reducing fasting blood glucose levels and increasing hepatic glycogen synthesis in HFD/STZ-induced diabetic mice. These findings revealed that MSP-II-a is a promising source of bioactive polysaccharides with potential hypoglycemic activity.

MORFOMETRIK LAMUN DI ZONA INTERTIDAL PERAIRAN PANTAI DESA ADMINISTRATIF MALAKU KECAMATAN SERAM UTARA KABUPATEN MALUKU TENGAH

Background: Seagrass is an angiosperm flowering plant that can grow well in coastal environments. Seagrass is a one seed plant that has roots, stems, rhizomes, leaves, flowers, fruit and seeds. Differences in substrate type, environmental conditions and nutrient content can influece the existence of seagrass species and their morphometric shapes.This research aims to determine the morphometric of seagrass in the intertidal zone of coastal waters of Malaku Administrative Village, North Seram Sub-district Methods: Sampling used a roaming survey method in the intertidal zone of coastal waters of Malaku Administrative Village. The research data were analyzed descriptively based on the results of species identification, observations and measurements of the segrass morphological structure. Results : The type of seagrass found in the intertidal zone of the coastal waters of the Malaku Administrative village is Cymodocea serulata, Cymodocea rotundata, Halophila ovalis, Halophila minor, Halodule pinifolia, Halodule uninervis, Thalassia hemprichii, and Syringodium isoetifolium. Morphometric forms of seagrass include : Root length ±3cm-16,5cm. Rhizome distance ±1cm–4,5cm. leaf blade length ± 2,4cm-15cm. The shape of the leaf blade is flat, oval, cylindrical, serrated at the tip of the leaf and small in length. Leaf width ±0,2cm-1cm, seagrass stand heigth ± 3-19,3cm. Conclusion: From the research results obtained, it can be concluded that the intertidal zone of the coastal wters of the malaku administrative village are 8 (eigth) types of seagrass and have morphometric structure that vary in size.

Investigation of Vertical-axis Tidal Turbine Mechanical Strength using FSI Analysis based on Blade Profile

Abstract Tidal energy, as a renewable energy source harnessed from the ocean, holds substantial promise owing to its heightened energy density, reliability, and longevity. An investigation encompassing the deployment of tidal stream electricity from 2003 through August 2020 revealed that blade malfunction was identified as the primary reason for system failures, with generator and monitoring system failures occurring subsequently. The majority of the research that has been done on the design of vertical-axis tidal turbine blades has focused on how well the blade performs in terms of power output without taking into account the generation of mechanical force. This force can potentially shorten the blade’s lifetime when implemented in a real-world scenario. By modelling a steady-state fluid-structure interaction (FSI) configuration, this study examines how the shape of the turbine blades affects the amount of mechanical force they generate, particularly in vertical-axis tidal turbines. The type of blade profile is the variable under consideration, and the stress levels experienced by a structure are influenced by the type of blade profile used. When comparing symmetrical and asymmetrical NACA straight blade types under similar climatic conditions, it has been found that the blade profile plays a significant role. Asymmetrical blade profiles, in particular, generate a higher lift force compared to symmetrical ones, thereby affecting stress levels more noticeably.

Development of a flexible phased array electromagnetic acoustic testing system with array pickups

The thermal barrier coatings (TBCs) used to protect blades of heavy-duty gas turbines is prone to debonding defects during fabrication and service. It is difficult to detect the debonding defects in the TBC system non-destructively and in situ due to the curved shape of blade and the narrow space between the blades setting in the gas turbine. In this paper, a flexible phased array electromagnetic acoustic (FPA-EMA) testing system with array pickups is developed, which is capable to drive a flexible phased array electromagnetic acoustic transducer (FPA-EMAT) to generate and receive ultrasonic wave directly in the metallic substrate of TBCs, and is potential to be applied to the inspection of debonding defects in the TBC system of gas turbine blades. A phased array excitation unit, a multi-channel signal receiving unit and a new signal post-processing algorithm are developed for the new EMA testing system to enhance the surface acoustic wave in the layered structure and to improve the low conversion efficiency of the conventional EMA testing system. In addition, a bias magnetic field coil fed with long pulse current of large amplitude is adopted to make the new EMAT thin and flexible in order to be applied in a narrow space. The interfering noise and geometric size problems brought by the multiple excitation and pickup channels are well addressed in the new system. The good performances of the developed FPA-EMA testing system were verified experimentally and show the system of good potential to be applied to NDT of practical curved structures.

Research on the technical improvement of the turbine runner of a power station based on improving stability

AbstractIn view of problems such as the narrow efficiency area, large hydraulic vibration area, pressure pulsation, and serious sediment wear of turbines at the Futang hydropower station, the technical transformation of turbine runners was carried out by modifying the blade shape and increasing the blade thickness, and a combination of numerical simulations based on shear stress transport k–ω turbulence model and tests was adopted to improve the operational stability of power station units. Calculation and testing demonstrate an enlargement of the high‐efficiency zone. Specifically, the optimal efficiency of the runner increases by 0.37%, while the rated efficiency rises by 0.19%. Significant reductions are observed in pressure pulsation within the draft tube and vaneless area decrease of approximately 50%. There is a high‐frequency pressure pulsation in the vaneless zone and the runner under low‐load conditions, and the influence of dynamic and static interference gradually weakens with the increase of opening. The draft tube is prone to eccentric vortex bands under partial working conditions, which causes the unit to be affected by low‐frequency pulsation. This optimization also leads to a notable decrease in runner blade wear, with the maximum sand and water velocity reduced from 45 to 40 m/s, resulting in a 30% reduction in sand wear. Moreover, there is a substantial enhancement in the runner's stiffness, with the thickness of the blade near the high stress area of the upper crown and lower ring increasing by over 50%, and the weight of each individual blade increasing by more than 50%. These research findings validate that modifying the runner blade effectively improves flow patterns, reduces eddy current generation, minimizes pressure pulsation, widens the high‐efficiency zone, decreases wear, and enhances the operational stability of the unit. The technical transformation method and research results of this study have important guiding significance for similar technical transformation of other power stations

The method for comparing different blade shapes of flat knives of a rotary cultivator

BACKGROUND: In the process of tillage, flat knives of rotary cultivators are to carry out the process of cutting soil and weeds with minimal energy consumption and not to become clogged with weeds, which is due to the compliance of the parameters of their blades with operating conditions. However, despite the abundance of works devoted to the study of the working process of flat knives of rotary cultivators, there is not any method of a comparative assessment of the various shapes of their blades. AIM: Development of the method for comparing different blade shapes of flat knives of rotary cultivators. METHODS: The research design included studying the following issues: clarifying the conditions for weeds to fall off the curved blade of a flat knife performing a plane-parallel movement; determining the equation of the curve of a knife blade that satisfies the condition of weeds to fall off the blade; development of methods for comparative analysis of the energy intensity of the process of cutting soil with flat knives with blades of various shapes; experimental verification of theoretical conceptions. The study objects were the processes of interaction of weeds and soil with the blades of flat knives of various shapes. The studies were conducted during 2022 and 2023. RESULTS: The condition for weeds to fall off the curved blade of a flat knife performing a plane-parallel movement has been clarified (a more informative form of notation), based on which an equation for the rational curve of the blade has been obtained. The comprehensive method has been developed for comparing different shapes of blades of flat knives of rotary cultivators, according to the criteria of compliance with the condition of weeds to fall off the blade and the energy intensity of soil cutting. Examples of the application of the method for the analysis of various shapes of blades of flat knives of rotary cultivators and the development of one of the effective shapes, as well as the results of experimental studies are given. CONCLUSION: The proposed method helps to give specific practical recommendations on the advisability of using knives of one shape or another in the operating conditions under consideration, taking into account the operating parameters of the machines, as well as to create effective combined blades.

Optimization of Lost Foam Coating Performance: Effects of Blade Shape, Stirring Speed, and Drying Temperature on Viscosity, Coating Weight, and Surface Morphology

The current investigation focuses on the viscosity, coating weight, and surface characteristics of lost foam casting coatings, examining the effects of blade shape, stirring speed, and stirring time. A systematic analysis was conducted to determine how different stirring speeds and durations influenced coating weight and viscosity. The results indicate that the blade shape has a considerable impact on the uniformity and efficacy of the coating, with some designs being far more effective in reaching the optimal viscosity and coating weight through uniformly distributed mixing. Results were consistently obtained when stirring at 800–1200 rpm. It was demonstrated that while stirring speed significantly impacts coating deposition, it has small effect on viscosity. A stirring time of 30 min was found optimal for stabilizing coating weight and viscosity without significant variations. Drying at room temperature produced smoother surfaces with fewer cracks, whereas higher drying temperatures (50 °C) were associated with increased surface roughness and cracking. Crack analysis after drying revealed that coatings mixed with the tri-blade had the lowest tendency to crack, demonstrating its superior capability for even and thorough mixing.

Optimization design method based on parameter reduction and active subspaces: Redistribution of chordwise loading at blade tips in a transonic axial-flow fan

In practical optimization design, an excessive number of design variables have a highly detrimental influence on the efficiency and accuracy of the final design scheme and expose the optimization problem to the curse of dimensionality. Therefore, incorporating only the most essential variables into an optimization design problem facilitates obtaining accurate and cost-efficient solutions. Reported here is an optimization design method based on parameter reduction and active subspaces, and it is used to redistribute the tip load in a transonic fan. Specifically, a coupled design strategy is developed to reduce the number of parameters needed to describe the three-dimensional blade shape, which leads to far fewer design variables being involved in the optimization design. Moreover, active subspaces are used to perform sensitivity analysis and establish low-dimensional surrogate models. After the coupled design, a blade is represented effectively by only three parameters, each of which has a significant influence on the fan performance. Three one-dimensional active subspaces are established for maximum mass flow rate, maximum total pressure ratio, and maximum efficiency, based on which the linear surrogate models are obtained. Next, the chordwise tip blade loading is optimized, after which the rotor efficiency at the design point is increased by 1.1%, while the total pressure ratio remains nearly unchanged. Finally, the flow field is analyzed to understand the mechanism for this performance improvement, and the results show that the optimized blade loading reduces the aerodynamic losses caused by shock-induced flow separation and the interaction between shocks and tip leakage flows.

A novel efficient calculation method for rotor aeroacoustic characteristics based on multiple aerodynamic surfaces source model

Based on the simplified acoustic source model of multiple aerodynamic surfaces, an efficient calculation method for rotor aeroacoustic characteristics has been established. Firstly, the aerodynamic characteristics database of the airfoil is obtained based on the Computational Fluid Dynamics (CFD) method. The inflow environment of each blade element is calculated using the free wake method, and the distribution of chord-wise loading is obtained by combining the established database. Subsequently, based on the F1A equation, a simplified formula for loading noise with pressure difference as a parameter is derived. The thickness noise is obtained from the blade shape and operating conditions, and the blade surface mesh is constructed by using the adaptive curvature distribution strategy of airfoil points. The validation is carried out by comparing with experimental values in the hover and forward flight states. Then, A hybrid weighted interpolation scheme is proposed based on inverse distance weighted interpolation (IDW) and bidirectional linear interpolation method, which is suitable for capturing blade/vortex interaction (BVI) noise. A set of parameters suitable for engineering applications is obtained through the parametric sensitivity analysis. The computational time and memory usage are reduced to 1/47 and 1/4 of the original amount, respectively. Finally, Using the above method, the influence of rotational speeds (ω) on rotor aeroacoustic characteristics are studied. The results show that ω and sound pressure level (SPL) are linearly related and the SPL decreases by approximately 5 dB for every 0.1 Ω decrease in ω. The rotational speed ω≈90 %Ω can effectively suppress rotor aeroacoustic levels, benefiting the stealth design of helicopters.

A PLATZ transcription factor PhePLATZ8 from Moso bamboo (Phyllostachys edulis) plays a positive role in regulating growth and abiotic stress tolerance

Moso bamboo is recognized as a rapid-growing plant with abundant lignocellulosic content, making it a crucial non-timber forest resource on a global scale. The growth of Moso bamboo is influenced by the rapid division and elongation of its internode meristem cells, but the molecular mechanism behind this process is still unclear. Here, by combining RNA-seq data from Moso bamboo internode samples with gene co-expression network and gene functional annotation enrichment analysis, a key candidate gene named PhePLATZ8, which regulates cell division in the internodes of Moso bamboo, has been screened out. PhePLATZ8 is localized to the nucleus and cytoplasm. The phenotype of transgenic Arabidopsis thaliana plants showed that PhePLATZ8 positively regulated the organ development of transgenic plants, including hypocotyl length, plant height, petiole length, blade shape, and seed size. Overexpression of PhePLATZ8 also significantly improved cell proliferation activities in the hypocotyl calluses of transgenic plants. qRT-PCR and luciferase assays showed that PhePLATZ8 was involved in the regulation of cell proliferation by activating the expression of several GRFs in A. thaliana and Moso bamboo. Futhermore, PhePLATZ8 was significantly induced by abiotic stress, and overexpression of PhePLATZ8 increased the tolerance of transgenic A. thaliana plants to drought and salt stress. Overall, our current study initially explored the role of PhePLATZ8 in the process of rapid growth and stress response of Moso bamboo, providing genetic resources for future molecular breeding of Moso bamboo.

Blade shape optimization in hover and forward flight

Blade shape optimization in hover and forward flight

Investigation of control method on blade shape accuracy of blisk in vibration finishing

Investigation of control method on blade shape accuracy of blisk in vibration finishing

A novel multi-fidelity optimization framework for high-altitude propellers

A novel optimization methodology is presented for optimizing high-altitude propellers operating in the lower stratosphere. The proposed methodology combines a Bayesian optimization approach for most design variables and Vortex Theory for the optimization of twist distribution and rotational velocity. For the Bayesian optimization part of the problem, a multi-fidelity approach is employed with three levels of modeling fidelity. The considered fidelity levels, from lower to higher, are: Vortex Theory, and 3D Reynolds-Averaged Navier-Stokes (RANS) with the use of γ−Reθ transition model, converged with first-order upwind, and second-order upwind for the momentum equations. Additionally, the optimization problem involves two objectives: maximizing the cruise efficiency and minimizing the total volume of the propeller. To enhance the performance of multi-fidelity, multi-objective (MFMO) acquisition functions, a novel algorithm is proposed. The proposed optimization methodology demonstrates its effectiveness in generating several high-performing propeller designs and proves to be more efficient than an equivalent problem formulation relying solely on Bayesian optimization. Post-processing of optimization data reveals new design variable bounds that correspond to more efficient blade shapes. These findings provide insights into some important geometric features of high-altitude propellers and establish guidelines for future optimization efforts within the specified thrust and power consumption ranges. Finally, simulations of the best-performing designs across a range of advance ratios and altitudes confirm their high performance in various operating conditions.

Pragmatic Prediction Model of Droplet Trajectory in a Turbine Cascade

Abstract Droplet deposition on a turbine cascade is important for the turbine system performance but its experimental analysis is difficult. Thus, the simulation of a droplet liquid phase in a gas flow field was studied to optimize turbine cascade design. However, the computational fluid dynamics (CFD)-based approach for such droplet problems requires enormous costs. Thus, the application of CFD simulation in the turbine blade's early-stage design is challenging, requiring iterative optimization for adjusting design with performance prediction. Therefore, this study proposed an analytical prediction method, having a reasonable cost and moderate accuracy, as an alternative to the whole multi-phase numerical simulation approach. The proposed method predicts droplet motion using the outline of the turbine blade and gas–liquid physical properties. Furthermore, the approach was validated by performing a three-dimensional Eulerian–Lagrangian simulation with low-pressure turbine blade T106. It was found that the droplet trajectories in the turbine cascade are governed by Stokes number. Furthermore, the streamlines of the gas flow were characterized by the shape of the turbine blade. The proposed model reproduced droplet trajectories obtained using CFD within an error margin of 10%. Consequently, it was concluded that the proposed analytical model is a promising approach to predict the droplet trajectory in a turbine cascade, obtained by the three-dimensional numerical simulation at a low cost.

КРАСНИКА (VACCINIUM PRAESTANS LAMB.): РАЗРАБОТКА МЕТОДИКИ ПРОВЕДЕНИЯ ИСПЫТАНИЙ НА ОТЛИЧИМОСТЬ, ОДНОРОДНОСТЬ И СТАБИЛЬНОСТЬ

The purpose of research is to study the morphological and phenological characteristics of hybrid forms of V. praestans and to develop a methodology for testing for distinctiveness, homogeneity and stability based on them. The results of studying the morphological and phenological characteristics of hybrid forms of red grass (Vaccinium praestans Lamb.) in the natural and climatic conditions of the European part of Russia (Moscow, Kostroma, Khabarovsk Regions) are presented. V. praestans is an endemic plant of the Russian Far East and has high medicinal, food and ornamental value. The experiments carried out on the introduction of V. praestans show the possibility of its successful cultivation in the conditions of the European part of Russia, including for industrial cultivation. We tested 2 hybrid forms obtained from specimens from natural habitats (Sakhalin, Khabarovsk Regions). The current year's shoots of V. praestans are long or medium in size and have a pronounced anthocyanin color; leaves are large and medium in size, with a low or medium length-to-width ratio, with an ovate or broadly ovate shape of the leaf blade, with a weak or medium expression of anthocyanin coloring, sparse or medium pubescence of the leaf edge; inflorescences are short or medium in length, with large or medium-sized flowers, pink or slightly pink in color; fruits are spherical berries, large or medium in size, glossy, fairly dense, red or dark red in color. Peculiarities of flowering and fruiting of V. praestans have been revealed. The periods of the beginning of flowering and the beginning of fruit ripening are early or middle. For the first time in Russia and in the world, based on an analysis of the morphological characteristics of shoots, leaves, flowers and fruits, a methodology for testing the distinctiveness, homogeneity and stability of hybrid forms and varieties of V. praestans has been developed.