Blade Structure Research Articles

Design Optimization of Hammer Blade Crusher to Improve the Crushing Performance

China is a large agricultural country, each year will produce a large number of straw. The recycling of straw to China's agricultural development and environmental protection are very helpful, the recycling of straw is mainly energy, fertilizer, feed several uses, different uses need different crushing fineness, so adjust the crushing fineness can improve the recycling rate of straw. This paper mainly on the impact of straw crushing fineness factors for This paper focuses on the theoretical analysis and study of the factors affecting the fineness of straw crushing, and provides a general design plan for the crushing chamber.Firstly, the effect of different hammer and sieve gaps on the pulverisation fineness is studied and the straw pulverisation fineness is changed by changing the hammer and sieve gaps. The effect of hammer blade material, structure, arrangement, distribution density and hammer blade speed on the fineness of the straw is studied. Study the effect of the aperture size and arrangement of the sieve on the fineness of the crushing, and adjust the fineness of the crushing by changing the aperture size of the sieve. The study of the material in the crushing process generated by the "ring flow layer" mechanism, and by changing the shape of the crushing chamber structure to destroy the "ring flow layer" on the impact of the crushing performance of the crusher.Secondly, according to the production requirements of the hammer mill, the structure and material of the hammer blade and screen plate are designed and selected, and the hammer blade is analysed statically using Ansys, the rotor is analysed modally, a complete model of the crushing chamber is designed, and a three-dimensional model of the crushing chamber is built using SolidWorks.Finally, after simulation calculations, the design of the rotor headquarters structure is reasonable. An adjustable hammer and sieve clearance was achieved, reducing costs and improving the efficiency of the pulveriser crushing.

A Novel Composite Helicopter Tail Rotor Blade with Enhanced Mechanical Properties

This paper describes the transition towards a composite structure, with the same overall aerodynamic characteristics, for a tail rotor blade of an IAR330 helicopter. The newly proposed structure of the composite blade is made of a carbon-roving spar embedded with epoxy resin, a hexagonal-cell honeycomb core manufactured by fused deposition modelling, and an outer skin made of multiple carbon-fibre-reinforced laminae. The blade was manufactured by the authors using the hand lay-up method at a scale of 1:3 with respect to the real one, and all stages of the manufacturing process are extensively described in the paper. The experimental tests were performed on an Instron 8872 testing machine by applying a bending force on its free edge, similar to the testing methodology employed by various composite blade manufacturers. A three-dimensional numerical model of the tail rotor blade was conceived, analysed using the finite element method, and validated by comparing the numerical and experimental values of the maximum bending force. Further, the model was used for a complex finite element analysis that showed the very good behaviour of the proposed composite blade during flight and emphasized the main advantages brought by the proposed composite structure.

The Effect of Pulling Speed on the Structure and Properties of DZ22B Superalloy Blades

DZ22B alloy is commonly used as a blade material for aircraft engines and gas turbines, and its preparation process is an important factor affecting its performance. In the present work, a reliable numerical model is established through ProCAST numerical simulation and auxiliary experimental verification methods, based on which the effect of casting speed on the grain and dendrite growth of DZ22B superalloy blades is studied. The results indicate that increasing the pulling speed can reduce the spacing between secondary dendrites, which is beneficial for the growth of dendrites. Based on numerical simulation and experimental verification, it is suggested that the pulling rate of the directional solidification DZ22B superalloy blade should be 6-2mm/min variable speed pulling to improve the production success rate.

Blade Structure Analysis of 2 MW V-Shaped Vertical Axis Wind Turbine Using Numerical Simulation

The intensive research on large-scale Vertical Axis Wind Turbine (VAWT) couldprovide an alternative to Horizontal Axis Wind Turbine (HAWT) in offshore deployment for the future. Regarding this fact, this article develops a conceptual design of the VAWT blade structure and analyzes its feasibility using numerical simulation. The blade structure is designed for 2 MW Darrieus type V- shaped VAWT. The blade is tapered, 90m long, and inclined at 35° to the vertical axis. Initially, the blade design is tested for ultimate strength test according to IEC 61400-01 standard using aluminum alloy and homogenized composite material. In doing so, maximum aerodynamic loading on the blade is calculated after steady state 3-D RANS CFD simulation of the blade in ANSYS Fluent. The Finite Element Method (FEM) model of the blade is created using shell element in ANSYS Static Structural with structured meshing strategy, and tested with the aerodynamic load using the one-way Fluid-Structure Interaction (FSI) technique, to obtain mesh independent solution. The impact of the using 2, 3, and 4 number of shear webs is then analyzed on the selected mesh model of the blade. Finally, a four-shear web model of the blade is tested under extreme conditions. The thickness of the blade surface and shear web are varied to test maximum deflection at the tip, and maximum allowable strain of the blade. After obtaining the required blade structure, the deformation, maximum equivalent stress, and maximum equivalent strain for the blade are studied at rotation Tip Speed Ratio (TSR) of 5 under aerodynamic and gravitational loading, using both materials. The study showed significant deflection at the tip of the blade for the tower-less V-VAWT blade, suggesting an alternative support mechanism for the blade. Also, the study concluded that better structural robustness is achieved while using a composite material instead of an aluminum alloy. This article provides basis to study structural behavior of the novel V-VAWT blades and contribute to continuing research on obtaining optimized blade structure for such turbine.

Optimized Design of a Multistage Centrifugal Pump Based on Volumetric Loss Reduction by Auxiliary Blades

Throat ring leakage is a major factor deteriorating the performance of multistage centrifugal pumps. This paper focuses on the optimization of multistage centrifugal pumps by incorporating the principle of the Tesla valve and adding an auxiliary set of blades to the impeller body. By changing the direction and magnitude of the leaking fluid’s flow, the leakage volume of the impeller throat ring is reduced. The study results demonstrate that the experimental error in head calculation with numerical simulation at the optimal working condition was 0.65%, verifying the accuracy of the numerical simulation method. The leakage volume of the throat ring decreased by up to approximately 28.99% compared to the original structure, which significantly increased the pump’s head and overall efficiency. Near the optimal operating point, the pump’s head and overall efficiency increased by approximately 8.1% and 8.7%, respectively. The larger the flow rate, the greater the improvement in the pump’s head and total efficiency. Near high-flow operating conditions, the pump’s head and overall efficiency increased by approximately 116.45% and 110.84%, respectively. The auxiliary blade structure introduces a non-contact seal which, compared to traditional seal structures, improves seal life and reduces seal costs. Additionally, the auxiliary blades can shift the optimal operating point of the multistage centrifugal pump towards a higher flow rate, improving the pump’s delivery capability.

Designing Composite Adaptive Propeller Blades with Passive Bend-Twist Deformation for Periodic-Load Variations Using Multiple Design Concepts.

Four plausible design concepts are applied together to investigate composite bend-twist propeller-blade designs that show high twisting per bending deflection. The design concepts are first explained on a simplified blade structure with limited unique geometric features to determine generalized principles for applying the considered design concepts. Then, the design concepts are applied to another propeller-blade geometry to obtain a bend-twist propeller-blade design that achieves a specific pitch change under an operational loading condition with a significant periodic-load variation. The final composite propeller design shows several times more bend-twist efficiency than other published bend-twist designs and shows a desirable pitch change during the periodic-load variation when loaded with a one-way fluid-structure-interaction-derived load case. The high pitch change suggests that the design would mitigate undesirable blade effects caused by load variations on the propeller during operation.

Self-shrouded torsional blade model equivalence and blade vibration response analysis

In steam turbines, the operation of turbine blades can lead to vibrations, which may result in turbine accidents. Traditional calculation methods are difficult to use due to the complex structure of the torsional blade, and simulation analysis can be time-consuming. Therefore, it is necessary to use the equivalent model instead. Most of the previous studies have simplified the straight blade to a cantilever beam model without considering the shear effect, and used harmonic response analysis to study the vibration of the blade for simulation. The blade body of the torsional blade can be regarded as a torsional variable section beam, and the Timoshenko beam model is the same as the variable section beam. Therefore, the Timoshenko beam model can be regarded as the equivalent of the sheathed torsional blade. Considering the complexity of the calculation of the self-shrouded torsional blade model. According to the theory of Timoshenko beam, the model of the shrouded blade of Timoshenko beam with different torsion angles was established. The first sixth-order modes of the blade model and the vibration response of the adjacent blades under forced vibration are compared, respectively. The results show that the results obtained from the Timoshenko beam blade model considering the torsion angle are closer to the torsional blade model. In addition, the blade vibration response of the same model under different excitation force amplitudes was further compared, and the results showed that the vibration amplitude, acceleration and velocity of the shrouded blade increased with the increase of the excitation force amplitude. However, the magnitude of the inter-shroud collision force and the number of collisions between adjacent blade shrouds are non-linearly related to the amplitude of the excitation force.

Load Simulation Analysis of 1.5 MW Horizontal Axis Wind Turbine

Wind turbine blades are subjected to a variety of loads in actual operation, which are prone to deformation and cause the strain and stress concentration of the blade structure, thereby affecting the safe operation of the wind turbine and the service life of the blade. Therefore, a numerical simulation study on the coupling of wind turbine blade loads with their displacement, deformation, and stress is carried out. The results show that at the same wind speed, as the wind turbine speed increases, the pressure on the windward side of the blade increases, the negative pressure on the leeward side decreases, the pressure difference between the two sides increases, and the maximum pressure is distributed in the tip of the blade; the blade is under different loads, among which the aerodynamic load is the main factor affecting blade deformation and stress generation. The maximum deformation of the blade appears in the direction of the swing.

Mechanical Testing of Connections Blind Bolted to the Thick Glass-Fiber-Reinforced Polymer Spar Cap of a Decommissioned GE37 Wind Turbine Blade

Millions of tons of glass-fiber-reinforced polymer (GFRP) composite wind turbine blades are expected to age out of service over the next 30 years. Research is being conducted on repurposing these structures as new civil infrastructure products. The GFRP material in these decommissioned wind blades has been shown to retain significant strength and stiffness for second-life applications. However, for repurposing as new products, they will need to be connected to other structural members. The connections employed for this need to be designed, evaluated, and tested prior to their use. Here, we present the results of detailed testing of bolted connections for load-carrying appurtenances that will carry the phases and shield wires (e.g., insulators, crossarms, davits, guy wires, posts) to the spar cap of an 11-year-old 1.5 MW GE37 wind blade, intended for use as a repurposed transmission pole (i.e., a BladePole). Details of ASTM-type pull-out and bearing capacity tests using different types of blind bolts, and tests of a full-scale steel bracket connection called a “universal connector,” are reported. The effects of the different blind bolts, pin diameters, and loading directions relative to the composite laminate structure (longitudinal or transverse) for both the coupon- and full-scale connector bracket tests are described. The ability to design and construct robust connections for repurposed wind blade structures was demonstrated.

Aerodynamic performance optimization of vertical axis wind turbine with straight blades based on synergic control of pitch and flap

Low power efficiency is a critical reason that restricts the potential application of the vertical axis wind turbine (VAWT) in offshore engineering. Hence, efficiency enhancement is an essential topic for the VAWT design. This paper attempts to propose an improved active control strategy and a novel blade structure with a trailing-edge flap for H-type VAWT to improve the power outputs at different tip speed ratios (TSRs). The orthogonal experiment design (OED) method was applied to optimize the motion of pitch and flap at low and moderate TSRs. Subsequently, the output characteristics, including the coefficients of power, torque, tangential force, and thrust of the optimized pitch-flap (P-F) model and three other models, namely the base model, the pitch-only (P-O) model, and the flap-only (F-O) model, were compared. Besides, the flow structures and static pressure distribution on the blade surface were studied to reveal the mechanism of power increase. It was found that the synergic motion of pitch and flap could effectively suppress the flow separation and delay the dynamic stall around blade. The result indicated that enhancement of the P-F model in torque coefficient was over 130% and 60% at low and moderate TSRs compared to the base model. In addition, the synergic motion of pitch and flap was found able to reduce the load fluctuation of the VAWT. The improved active control strategy and the blade structure with a trailing-edge flap may be helpful for the potential application of the H-type VAWT in offshore engineering.

Mixing Transport Mechanism of Three-Phase Particle Flow Based on CFD-DEM Coupling

The mixing transport courses of three-phase particle flows exist in some industrial applications, such as metallurgy material extraction, lithium electric slurry dispersion, and material mixing in the high-end chemical industry. Its mixing transport mechanism is a fluid–structure coupling dynamic issues with intensive shear and nonlinear characteristics, making the real-time prediction of the flow field face challenges. To address the above problem, a bidirectional fluid–structure coupling three-phase particle flow dynamic model is built based on the coupled computational fluid dynamics and discrete element model (CFD-DEM) to explore the mixing transport mechanism. An interphase coupling solution method is utilized to solve the interaction effects of the fluid and particle. Research results illustrate that the proposed method modeling can well reveal the mixing transport mechanism of the three-phase particle flows. Due to the additive effects of stirring speed, stirring blade size, and stirring blade structure, the flow field near the blade has a high-velocity gradient change, while the flow field away from the stirring blade has no significant change. When the particle material settles and accumulates to a certain extent, the particle movement is blocked, and the stirring speed of the particle material near the blade is reduced. The mixing effect of the particle material will be reduced near the wall. It can provide a valuable reference for particle flow transport and pattern identification and support technical support for lithium electric homogenate mixing, chemical extraction, and pharmacy process regulation.

Parameter Optimization of Centrifugal Pump Splitter Blades with Artificial Fish Swarm Algorithm

Low specific speed centrifugal pumps typically suffer from low efficiency and severe backflow; adding optimally structured splitter blades can play a role. In this paper, the distribution of pressure and velocity in the flow channel is analyzed using CFD simulation for a low specific speed centrifugal pump. The geometric parameters of the splitter blade are optimized using an orthogonal test and an artificial fish swarm algorithm; then the optimal splitter blade structure is obtained. Results showed that the splitter blade not only effectively solves the backflow of the flow channel and compresses the range of the trailing vortex, but it also alleviates the cavitation at the inlet of the main blade. When considering the best head, the order of influence of each factor is: Splitter blade thickness > Splitter blade inlet diameter > Splitter blade inlet width. At this time, the thickness of the splitter blade is 4.5 mm, splitter blade inlet diameter is 155 mm (0.775) and Splitter blade inlet width is 23 mm. Through the closed pump experimental system, it is confirmed that hydraulic performance has been improved.

Research on the Effect of Heat Tensioning on the Dynamic Stability of Circular Saw Blades with External Scrapers

Abstract Heat tensioning was proposed and proved to be effective for improving the dynamic stability of circular saw blades with ideal disk structure by a previous scholar. With the diversification of circular saw blade structure, circular saw blades with external scrapers are widely favored by the market because of their excellent resistance to sawing thermal stress. For circular saw blades with external scrapers, the effect of heat tensioning on the dynamic stability of the blades needs to be further studied. Therefore, the heat tensioning process of circular saw blades with external scrapers was built by the finite element method. The stress field and critical rotational speed of circular saw blades with a different structure after the heat tensioning process were calculated and analyzed. The relationships between circular saw blade structure, the dynamic stability of circular saw blades, and the heat tensioning process are clarified in this article. The results show that heat tensioning is not valid for all types of circular saw blades. For circular saw blades with external scrapers, the effect of heat tensioning on improving the critical rotation speed of the blades is gradually decreased with the number of external scrapers. When circular saw blades are heat tensioned, the average tangential stress of the outer edge of the blades and the critical rotation speed of the blades are higher.

ANALYSIS AND IMPROVEMENT OF SINGLE-PHASE FLOW FIELD INSIDE THE CRUSHING CHAMBER OF MACHINE FOR LENTINUS EDODES STIPE CRUSHING

In order to analyze the flow field inside the crushing chamber of machine for lentinus edodes stipe crushing and improve performance of the machine based on the results of the flow field analysis, this paper applied the computational fluid dynamics software FLUENT to numerically simulate the flow field inside the crushing chamber of the machine for lentinus edodes stipe crushing. Thus, the flow field characteristics and flow state inside the crushing chamber were intuitively displayed, and the visualization of the flow field in the crushing chamber was realized. Then, the wind speed value obtained by simulation was compared with the value measured by experiment, and the average relative error between them was less than 10%. Finally, according to the simulation results of flow field, the flow field generated by one air inlet and two air inlets was analyzed, and then the blade structure, outlet area parameters, and rotation speed parameters were compared, simulated and optimized. Results analysis: the pressure distribution and velocity distribution of the flow field inside the crushing chamber were obtained, and the optimal structure and parameters were two inlets, the rotation speed of 2000 r/min and the outlet area of 160×80 mm2, the crushing chamber with the new blade parameters and structure had greater turbulent kinetic energy and velocity gradient, which was more favorable to the discharge, and provided a basis for further optimization and improvement of the crushing machine.

Alternative Manufacturing Processes (AMP) for Wind Turbine Blade Material, in Isolated Regime Based on AHP

The newest cutting-edge technologies in Renewable Energy Sources (RES) projects provides economic benefits for project developers, especially when installing a wind power in isolated regime. The research was focused on finding technological alternatives, using an optimal composite material for wind blades structure. In this sense, the research team made a decision based on critical analysis of today existing technologies that can provide feasible solutions. The Analytic Hierarchy Process (AHP) method provides results for choosing alternative manufacturing processes, suitable for blades structure, in isolated regime

Nonlinear Contact Stiffness and Damping Identification of a Tenon Connection Structure Based on Its Dynamic Characteristics

A tenon connection structure is widely used for the blade-disk connection in turbomachinery, and its contact stiffness and contact damping have caused nonlinear dynamic characteristics. The nonlinear dynamic characteristics of a blade-disk structure are mainly affected by its contact stiffness and damping characteristics, which are difficult to accurately predict and affected by many factors such as the operating speed and the centrifugal force caused by the rotation speed. Based on a single blade and tenon groove structure and the use of the dynamic characteristics experiments and simulations, the influence law of the contact stiffness and damping of the tenon connection structure with the change of the blade root compression force on the dynamic characteristics of the structure is obtained. The average relative error of identifying the contact stiffness is 0.48%; thus, identification of the nonlinear contact stiffness and damping of multiple pairs of contact curved surfaces is realized.

Simultaneous aerodynamic and structural optimisation of a low-speed horizontal-axis wind turbine blade using metaheuristic algorithms

AbstractThis work presents a concurrent design and multi-objective optimisation framework of horizontal axis wind turbine blades, made of composite material, for low wind speed. The optimisation model aims to minimise the structural mass of the blade whilst simultaneously maximising the turbine power output, subjected to three constraints viz. blade tip deflection, and Tsai-Hill and von Mises criteria. The design variables are blade shape and details of the internal blade structure. The control points and polynomial interpolation technique were adopted to determine the blade shape while the airfoil types at blade sections remained fixed. The internal blade structure design variables include the thickness of ribs and spars and the carbon fibre thickness and orientations. The blade element momentum approach is utilised to calculate turbine power and structural loads, whereas a finite element method is employed for structural analysis. Twelve multi-objective metaheuristics algorithms are used to solve the proposed multi-objective optimisation problem while their performance is investigated. The results obtained show that the multi-objective cuckoo search algorithm is the most efficient method. This study is said to be the baseline for a future study on multi-objective optimisation which combines two design stages of the composite low-speed wind turbine blades.

Effect of blade aspect ratio on the performance tradeoff between figure of merit and bending-torsion dynamics of wind turbines with synthetic jets

In this experimental study, two three-bladed rotors with a blade aspect ratio of 7.79 and 9.74 representing a 25% increase were tested. Each blade contains an S809 airfoil with zero pre-built twist and 20 high-performance synthetic jet actuators distributed along the span. The rotor was tested at four rotor speeds, Ω of 250, 500, 750, and 1,000 revolutions per minute (RPM) and three collective blade pitch angles, θc of 2, 5, and 8 degrees. Rotor thrust was measured using a high-capacity load cell, and blade bending and torsion was measured at four equally spaced radial locations on the blade defined by r/R= 0.24, 0.48, 0.72, and 0.96 using four onboard inertial measurement units. The spanwise flow over the suction surface of the blade was measured using laser Doppler velocimetry (LDV) techniques. The local Reynolds number produced with the test rotor speeds at the measurement locations ranges from 8.31 × 104≤Re∞≤ 9.49 × 105. It was found that rotor aerodynamic efficiency as quantified by the figure of merit is directly linked to blade aspect ratio and the magnitude of spanwise flow over the blade. The rotor with a higher blade aspect ratio produces less overall spanwise flow and is more aerodynamically efficient, however the blade also generates larger mean and fluctuating bending and torsion displacements, which are undesirable for aeroelastic stability. The use of synthetic jets on the blade mitigates the root mean square of the bending and pitch displacements above Ω= 250 RPM and θc= 2°. It was found that at Ω= 1,000 RPM, the blade structures undergo a second mode bending response indicating a condition of structural instability due to higher aerodynamic loading. At this rotor speed, flow control on the outboard of the blade reduces unsteady bending as quantified by arms up to a maximum of 36.5%, and unsteady torsion, θrms up to 22.9% compared to the baseline for the rotor with an aspect ratio of 9.74.

Design and analysis of underwater power generation characteristics of deflected double-stator switched reluctance generator

The Deflectable double-stator Switched Reluctance Generator (DSRG) has the advantages of simple structure, small volume and multi-dimensional operation. The DSRG and propeller are combined into the application of underwater power generation. With the help of the deflect ability of the generator, the efficiency is improved. Due to the uncertainty of ocean current direction and the structure of switched reluctance generator, the torque ripple is one of the important factors damaging the underwater generator. In order to effectively suppress the influence of torque ripple caused by generator operation, a method of adding pole shoes on the pole side of outer stator is proposed, so as to reduce the torque ripple. The propulsion structure running at different deflection angles is simulated. The torque and speed obtained before and after pole shoe optimization are input into the propeller model. The pressure and speed characteristics of the corresponding blade structure are simulated to verify the effect of optimization and the effectiveness of the power generation system.

Dwarfing Effect of Plant Growth Retarders on Melaleuca alternifolia

Rapid growth and scattered plant types are urgent issues for potted Melaleuca alternifolia. An effective strategy for dwarfing cultivation is the exogenous application of plant growth regulators (PGRs) to plants. However, for many non-wood forest species, there is currently limited understanding of the regulatory mechanism of dwarfing effects of PGRs, which greatly limits the application of PGRs. In this study, three PGRs, paclobutrazol (PP333), uniconazole (S3307), and chlormequat chloride (CCC) were applied to dwarf terpinen-4-ol M. alternifolia. By observing the morphological characteristics and leaf anatomy of M. alternifolia after dwarfing and measuring its photosynthetic characteristics and physiological and biochemical indexes, the dwarfing effect of the three PGRs and the underlying mechanisms were investigated to provide a reference for the cultivation of M. alternifolia by dwarfing. The results show that the PP333 (P3) treatment at 2000 mg·L−1 had the best dwarfing effect on M. alternifolia, with a compact plant shape, thicker stems, and green leaf color. At the same time, it increased the chlorophyll contents, changed the blade structure, increased the content of soluble substances and the activity of antioxidant enzymes, increased the endogenous hormones indole-3-acetic acid (IAA), gibberellin A3 (GA3), and trans-zeatin-riboside (ZR), and decreased abscisic acid (ABA) levels.