Blade Angle Research Articles

Experimentation and Analysis of Physical Properties Related to Quinoa Straws

To study the cutting mechanical properties of quinoa straw and reduce the cutting force and unit area cutting power consumption of quinoa straw, this study took quinoa from low-altitude areas as the research object. Through observation and experimental analysis of quinoa from low-altitude areas, the relevant external characteristics of quinoa straw were recognized, providing a certain research basis for the development of quinoa-specific harvesting machinery. In the cutting mechanical experiments, a reciprocating cutting test bench for straw was designed. Single-factor experiments were conducted on the moisture content, cutting speed, blade angle, and cutting angle of quinoa straw. Response surface experiments were conducted on cutting speed, blade inclination angle, and cutting inclination angle to reveal the variation laws of the cutting mechanical properties of quinoa straw, providing a scientific basis for the rational formulation of harvesting strategies. In the single-factor experiments, the ultimate cutting stress of the stem and the unit area cutting power consumption decreased with the increase in moisture content; the ultimate cutting stress of the stem and the unit area cutting power consumption decreased first and then increased with the increase in cutting inclination angle; the ultimate cutting stress of the stem decreased with the increase in blade inclination angle, while the unit area cutting power consumption decreased first and then increased; the ultimate cutting stress of the stem and the unit area cutting power consumption decreased first and then remained stable with the increase in average cutting speed. In the response surface experiments, the optimal parameter combination was an average cutting speed of 0.8 m/s, a cutting inclination angle of 9.8°, and a blade inclination angle of 33.2°. The verification test proved that the error was no more than 4%. Under the optimal parameters, the ultimate cutting stress and unit area cutting power consumption of the straw were 9.1% and 2.9%, respectively.

Enhancing the Operating Efficiency of Mixed-Flow Pumps Through Adjustable Guide Vanes

The guide vane mixed-flow pump is a crucial component in medium-to-low-head pumping stations. The guide vanes are mostly fixed in traditional designs. The efficiency of these pumps under off-design operating conditions tends to be low, leading to higher energy consumption. This study explores the design of an adjustable guide vane for the conventional guide vane of a mixed-flow pump at a certain pumping station. Through numerical simulations and two sets of three-factor, five-level orthogonal experiments, we investigate the impact of flow rate, guide vane angle, and impeller angle on efficiency. Through numerical simulation, we identify the optimal relationships between an impeller angle of ±2° and 0° and guide vane angles of ±6°, ±3°, and 0°, focusing on the entropy production rate (EPR) as a key performance metric. The results demonstrate that adjustable guide vanes significantly improve the performance of mixed-flow pumps under off-design conditions. Efficiency increases by up to 17.71% at high flow rates, and by up to 5.48% at low flow rates. Energy consumption is notably reduced. As the flow rate and impeller blade angle vary, the adjustable guide vane rotates to match with the impeller, enhancing flow adaptation, expanding the high-efficiency operating range, and reducing overall energy consumption.

АНАЛИТИЧЕСКОЕ ПРЕДСТАВЛЕНИЕ ЭЛАСТИЧНОСТИ И ОБОСНОВАНИЕ КРИТЕРИЯ КАЧЕСТВА ПРОЦЕССА СМЕШИВАНИЯ СЫПУЧИХ КОМПОНЕНТОВ

The purpose of the study is an analytical representation of elasticity and substantiation of the criterion for the process of mixing bulk components. Tasks: to develop an analytical model of the process of mixing bulk components, taking into account indicators of elasticity and to analytically substantiate the quality criterion for mixing bulk components. The process of high-quality mixing of bulk mixtures of plant components depends on the design of the equipment used. The analytical model and quality criterion of the process of mixing bulk components are developed for the patented design of the paddle mixer. Wheat grain and millet were used as components of the mixture. The factors in the studies were: the angular velocity of the paddle mixer shaft; blade angle; millet content in the mixture. The target optimization functions were: the variability of the mixture, the energy intensity of the process of mixing bulk components, as well as a generalized indicator representing their convolution. The computer package Maple was used for the computational experiment. The proposed criterion for the quality and efficiency of mixing is presented in an analytical form as a maximization criterion, and the technological task of improving the process, accordingly, turns into a problem of conditional optimization. At the optimum points, the "mixed" generalized indicator has the property of elasticity – "sensitivity" to the control of the mixing process. The criterion of quality (efficiency) of the process of mixing bulk plant components was proposed to agree on the goal of increasing the productivity (high energy intensity) of the mixing process while ensuring its stability (low variability). The numerical values of the maxima at different levels are determined. When choosing the angular speed of rotation of the shaft, the angle of inclination of the blades, the content of millet in the mixture at a variation level not exceeding 1.85 %, the maximum energy intensity of the mixing process is achieved.

An Enhanced Jig-Shape Approach to Lifting Propeller Design

The jig-shape approach decouples the design process of aeroelastic structures. During structural sizing, elastic deformations are subtracted from the initial shape to achieve a desirable flying shape under loads at one specific design point. However, due to nonlinear loads, stiffness, and deformations, there is a disparity between intended rigid and actual elastic propeller performance at off-design points. Propellers lifting air taxis or large cargo drones are particularly susceptible to such variances due to their slender design. This paper presents an enhanced jig-shape approach to minimize these discrepancies by inducing additional coupling effects counteracting elastic deformations. Beyond the traditional single-point predeflection analysis, the improved strategy employs geometric and structural modifications to mitigate errors at off-design points. Comparing the aeroelastic performance of propellers sized according to the traditional and the enhanced procedure illustrates the effectiveness of the modifications. The enhanced approach remains computationally efficient due to its decoupled nature. A novel finite beam element that accurately captures the relevant structural coupling effects of lifting propellers is derived. Applying unbalanced ply layups inducing extension–twist coupling is limited in effectiveness and increases weight. Modifying the coning angle of a straight blade affects loads and stresses but does not allow the adjustment of aeroelastic performance. Combining the coning angle with a swept planform enables the flexible correction of aeroelastic performance within limits at minimal weight increase.

ARCHIMEDES OPTIMIZATION ALGORITHM-BASED PITCH ANGLE CONTROL IN WIND ENERGY SYSTEMS

Variable-speed wind energy systems equipped with permanent magnet synchronous generators (PMSGs) have become a common configuration in wind energy industry. Appropriate pitch angle control is designed to limit the output power of the system by adjusting the pitch angle of the wind turbine blades at higher wind speeds. This approach reduces mechanical stress on the turbine, extends its operating speed range, and increases the overall lifespan. Intelligent control methods, such as optimization algorithms, are notable for their fast and reliable control performance; however, their use in pitch angle control applications remains relatively limited. In this study, a pitch angle control based on the Archimedes Optimization Algorithm (AOA) was developed and analyzed using MATLAB/Simulink. The proposed control system demonstrated fast and stable performance at higher wind speeds. Additionally, the control mechanism was set to deactivated at lower wind speeds to optimize energy efficiency for varying conditions. When compared to other conventional control methods, alternative approaches generally achieve an average accuracy of %75 to %80. However, the proposed control method performed a significantly faster convergence speed and achieved an accuracy rate exceeding %90.

CFD-Based Investigation of the Operation Process of Radial Labyrinth Machinery Under Different Geometrical Configurations

This study explores the performance and flow characteristics of radial labyrinth pumps (RLPs) under various geometrical configurations and operating conditions. Experimental investigations and numerical simulations were conducted to evaluate the impact of design parameters such as blade geometry, channel width and blade angle on pump hydraulic performance. The numerical model, developed using the realizable k-ε turbulence model, was validated with experimental data, achieving satisfactory convergence (4.8%—bladed active disc operating with a smooth passive disc and 3.0%—bladed active disc operating with a bladed passive disc). Analysis of the velocity profiles and vortex structures formed between the active and passive discs was performed. These findings underscore the importance of optimizing disc geometry to balance centrifugal effects and momentum exchange. The obtained head for the model with a bladed active disc operating with a smooth passive disc was H = 24.1 m, while, for the bladed active disc operating with a bladed passive disc, it was almost 1.7 times higher at H = 40.3 m. Additionally, the research identifies potential zones within the pump where energy transfer processes differ, providing insight into targeted design improvements. The findings provide valuable information on the optimization of RLP designs and their broader applicability.

Optimal Design of a Liquid Hydrogen Centrifugal Pump Impeller

Global energy consumption has continued to increase in recent years with economic development. Fossil energy sources are now being replaced with renewable energy, and hydrogen is one of such alternatives. Pumps are used for storage, transportation, and distribution. One such pump is the liquefied hydrogen centrifugal pump. In this study, optimisation design of a liquefied hydrogen centrifugal pump was performed using the response surface method, which is the optimisation method of the DesignXplorer provided by ANSYS, based on the flow analysis results of the impeller of the centrifugal pump. The design variables used in the optimisation process are the outlet width b2, % of the blade thickness Su2, leading edge inclination angle α, hub inclination angle δ, wrap angle θ, and outlet blade angle β2. The optimisation analysis results obtained confirmed that all the selected design variables are semi-galactic and are sensitive to pump efficiency and head. It was confirmed that the efficiency of the centrifugal pump achieved using liquefied hydrogen as the working fluid is approximately 82.4%, which is significantly higher than that achieved by a centrifugal pump using water as the working fluid under the same operating conditions.

Experimental investigation of the flow disturbance near the trailing edge of slotted and non-slotted blades using skewness and kurtosis

ABSTRACT The present study conducts an experimental investigation into the flow characteristics over a cascade of both slotted and non-slotted compressor blades. The focus is on evaluating potential statistical correlations between higher-order moments of velocity fluctuations, including Skewness and Kurtosis. The linear axial cascade comprises three NACA6409 blades, which are tested in both normal and slotted blade. Data acquisition was conducted using a hot wire anemometer at three measurement stations within the cascade. The hot wire sensor was positioned at distances of x/c = 0.125, 0.25, and 0.5 from the trailing edge (x), where x represents the distance from the probe to the trailing edge of the airfoil and (c) is the chord length of the blade. Measurements were taken at a blade angle of attack of 0° and two Reynolds numbers: 22,750 and 45,500. Results indicate that blade grooving enhances flow velocity, postpones separation and improves flow control in the trailing edge region. By comparing calculated Skewness and Kurtosis values with those predicted by existing boundary layer and free jet relations, more consistent correlations were identified. To provide more accurate relationships, two polynomials of the second and third order have been used. It was found that high-order values of velocity were obtained more accurately with the relations presented in this research. Although the accuracy of these predictions is significantly reduced in the proportion of larger distances. In distant stations, the loss velocity has decreased. As the distance from the model increases, the amount of inhomogeneities in the sequence increases and the values of the opposite Skewness become zero. Turbulence intensity has been reduced by slotting the blades.

NUMERICAL STUDY OF FLOW PARAMETERS IN THE HIGH-HEAD FRANCIS TURBINE

The scientific exploration of numerical computation regarding spatial flow within hydraulic machinery components is examined. A survey of contemporary software systems is conducted, and the benefits of their utilization over experimental studies are evaluated. It is indicated that the optimal approach involves a blend of experimental investigations and numerical simulation. This methodology facilitates the validation of simulation outcomes under real-world conditions and iteratively enhances the model based on acquired data. A review of the widely utilized Ansys software program is provided, emphasizing its pivotal features and capabilities for analyzing flow components of hydraulic turbines. An algorithm for computing flow parameters in hydraulic turbines using the Ansys software suite is outlined. The subject of this study is the high-head Francis hydraulic turbine Fr 500. The turbine's geometry was constructed employing a sector-based approach. This technique allows for significant simplification of calculations within the computational fluid dynamics framework, thereby reducing computational workload while preserving result accuracy. In selecting mathematical and turbulence models, a comprehensive analysis of the problem was undertaken, identifying models most suitable for the specific situation to ensure dependable numerical simulation outcomes. For spatial flow calculations in the turbine's flow component, the standard k-ε turbulence model was adopted. Considerable attention was devoted to mesh generation, as mesh quality strongly influences result accuracy and reliability. An unstructured mesh comprising tetrahedral-shaped cells was employed for discretizing the flow component, with local mesh refinement at the edges of the runner blades and guide vanes. As a result of numerical computations, the values of primary flow parameters for the design operating mode were determined. A visualization of the flow within the flow component is provided, alongside the assessment of hydraulic losses and turbine efficiency. The efficiency values obtained differ from corresponding experimental values by no more than 1 %. A thorough examination of the flow structure within the flow path was conducted, yielding recommendations for adjusting the blade angle β1 to reduce inlet impact losses.

Integrated DNN and CFD model for real-time prediction of furnace waterwall slagging of coal-fired boiler

Slagging of furnace waterwall adversely affects the thermal performance and increases the operation and maintenance costs of coal-fired boilers. A real-time slagging prediction model is of great significance for the plant operators to monitor the furnace slagging conditions and make appropriate operation of soot blowers to maintain the cleanliness of waterwall. Three-dimensional (3D) computational fluid dynamics (CFD) can predict detailed furnace slagging distributions, but its high computational cost has been the major impediment hindering its application in large-scale combustion systems that require real-time information. To resolve this problem, a CFD-based deep neural network (DNN) model framework was developed in this study to realize the real-time prediction of furnace wall slagging distribution. A 3D CFD model was first developed and employed to generate the slagging database under typical boiler operating parameters. Then this database was utilized to train the DNN model to capture the mapping relationship between boiler operating parameters and wall slagging distributions. The core idea of this CFD-based DNN model is to generalize the wall slagging distributions under different boiler operating conditions based on this mapping relationship learned by the DNN model. This model was applied to a 350 MW coal-fired boiler. The prediction results by the CFD model demonstrated that the boiler operating parameters, such as boiler load and coal burner swirling blade angle, have strong effects on furnace wall slagging distributions, while the DNN model could precisely capture their relationship and make predictions with deviation from the CFD results below 5 %. More importantly, the DNN model could give the prediction results within seconds that is three to four orders of magnitude faster than the CFD model. Thus, it can respond to the rapidly changing boiler operating conditions and realize the real-time prediction of furnace wall slagging distributions.

Optimizing ventricular assist device rotor design parameters through computational fluid dynamics and design of experiments.

Heart failure is among the most widespread diseases globally. With the rapid rise in the number of affected individuals and the significant disparity between organ demand and supply, the relevance of implantable devices has grown each year. However, these devices face various regulatory restrictions, and obtaining approval requires outstanding performance. This paper focuses on optimizing the design parameters of a rotor for an axial flow ventricular assist device (VAD) currently under development. The parameters investigated include splitters, inlet blade angle, outlet blade angle, blade count, rotational speed, clearance gap, blade thickness, and rotor length. The study aims to maximize pressure rise and hydraulic efficiency while minimizing the torque required to drive the rotor. The D-optimal method was employed to create an experimental design for the simulations. By comparing R², adjusted R², and RMS error across different regression models, the quadratic regression model emerged as the most effective for deriving a suitable mathematical model from the numerical results. The validity of these models was confirmed through the consistency between predicted and observed outcomes.

Optimization of guide blades structure for swirl growth tube based on revised steam phase change particle agglomeration model

This paper presents a particle steam agglomeration device to enhance the efficiency of particle separation. The experimental study shows that this technology can improve the agglomeration efficiency and improve the particle separation efficiency. In order to delve into the mechanism of steam phase change agglomeration, a mathematical model considering agglomeration efficiency and relative motion of multiphase flow was established, and the reliability was verified by comparing with the experimental results. Furthermore, a new type of cyclone growth tube was designed to analyze the effect of the guide blade angle on particle growth and agglomeration. The results indicated that decreasing the blade angle resulted in a decrease in temperature inside the tube, an increase in supersaturation degree, and an increase in average particle size. However, when the blade angle is inadequate, there will be a significant pressure drop between the inlet and outlet, leading to the "eccentric phenomenon," which is not conducive to particle condensation growth. The optimal range of 22.5°–27.5° was determined by considering pressure drop, flow field stability, and agglomeration efficiency.

Numerical formulation of relationship between optimized runner blade angle and specific speed in a francis turbine

Francis turbine is the most widely acceptable hydraulic machine due to its higher efficiency. The establishment of the link between the optimized blade angle and specific speed can provide a turbine model with increased efficiency. In this study, a numerical study was conducted to derive the correlation between runner blade angles and the specific speed (NS). The blade angles at the inlet and outlet of the hub and shroud spans were selected as the design variables. For the numerical calculations, Reynolds-averaged Navier-Stokes equations were modelled with the Shear Stress Transport turbulence model to predict the hydraulic performances. The Grid Convergence Index technique was applied to ensure grid accuracy. Response surface methodology was used as an optimization technique to derive the optimal model with higher efficiency. Based on the optimized blade angles, the efficiencies are improved by 1.12 % and 1.42 % at NS=150 and 270 respectively with a constant power output of 30 MW. For both NS, the internal flow characteristics were improved with a reduction of 24 % in the circumferential velocity at NS=150 and 43 % in the low-speed zone area at NS=270. The correlation was established to formulate a basis for providing a runner's blade angle value close to the optimal point for a wider range of NS of the turbine.

Enhancing Oxygen-Dissolving Capacity of Rotary Drum Food Waste Composting: Tumbling Process Optimization and Experimental Validation with Discrete and Finite Element Methods

An optimized tumbling process can significantly improve the oxygen dissolving capacity of composting and fertilizer quality: by increasing the fluffiness of the lower layer of the pile, localized anaerobic fermentation can be avoided, thereby enhancing compost quality. This paper presents a method for improving the oxygen dissolving capacity of rotary drum food waste composting through a combination of simulation optimization and experimental validation. First, the discrete element method was used to optimize the key parameters of the tumbling process. The response surface method was then employed to analyze the composting test results and determine the optimal conditions. To ensure the reliability of the equipment under this method, failure risk analysis was conducted using the finite element method. The simulation optimization results showed that with a rotary drum reactor speed of 3.5 r/min, a horizontal angle of inclination of 2.5°, a mixing blade angle of inclination of 43°, and a blade pitch of 580 mm, the fluffiness of the lower layer of the pile increased by 8.515%, achieving the best tumbling and indirectly enhancing oxygen dissolving capacity. The maximum deformation of the load-bearing components was only 0.0548 mm, and the minimum safety factor was 4.408 (≥1 is considered safe). A 14-day composting experiment was conducted to validate the optimized parameters. The results showed that the maximum temperature of the compost pile reached 68.34 °C (lasting 7 days), with the pH, moisture content, C/N ratio, humus substances, humic acid, and fulvic acid contents of the fertilizer all meeting or exceeding the levels recommended by Chinese national standards. These findings indicate that the optimized tumbling device effectively improved the stability and dissolved oxygen efficiency of food waste composting, providing valuable practical insights and a research foundation for enhancing oxygen efficiency in the composting of other organic wastes.

Flow analysis and optimization study of main components of flow-type small hydro turbine system

Abstract Small hydro power generation refers to the production of electricity by harnessing the kinetic energy of water in small rivers or streams, typically generating up to 10 MW of power. The optimal shape combination of the watercone and turbine, according to the water flow rate, is crucial for maximizing the power generated. In this study, flow analysis using computational fluid dynamics was performed on Kaplan turbines to examine the effects of blade angle, volume flow rate and rotational speed on power generation. To ascertain the impact of variables on power generation, the internal flow field was examined. The findings demonstrated that an increased blade angle perpendicular to the flow direction resulted in a reduced incidence of vortices and cavitation formations within the turbine wake. A predictive model was generated using a design of experiment and response surface methodology to generate a predictive model to find the power generation for flow rates, blade angles and rotational speed within the experimental range.

Evaluation and optimization of interventional blood pump based on hydraulic performances and hemocompatibility performances

This study was designed to investigate the effects of hemodynamic environment and design factors on the hydraulic performance and hemocompatibility of interventional blood pumps using computational fluid dynamics methods combined with specialized mathematical models. These analyses assessed how different hemodynamic environments (such as support mode and artery size) and blood pump configurations (including entrance/exit blade angles, rotor diameter, blade number, and diffuser presence) affect hydraulic performance indicators (rotational speed, flow rate, pressure head, and efficiency) and hemocompatibility indicators (bleeding, hemolysis, and thrombosis). Our findings indicate that higher perfused flow rates necessitate greater rotational speeds, which, in turn, reduce both efficiency and hemocompatibility. As the artery size increases, the hydraulic performance of the pump improves but at the cost of worsening hemocompatibility. Among the design parameters, optimal configurations exist that balance both hydraulic performance and hemocompatibility. Notably, a configuration without a diffuser demonstrated better hydraulic performance and hemocompatibility compared to one with a diffuser. Further analysis revealed that flow losses primarily contribute to the degradation of hydraulic performance and deterioration of hemocompatibility. Shear stress was identified as the major cause of blood damage in interventional blood pumps, with residence time having a limited impact. This study comprehensively explored the effects of operating environment and design parameters on catheter pump performance using a multi-faceted blood damage model, providing insights into related complications from a biomechanical perspective. These findings offer valuable guidance for engineering design and clinical treatment.

Numerical simulation and experimental study of energy dissipation in a bidirectional axial extended tubular pump with different blade angles

Numerical simulation and experimental study of energy dissipation in a bidirectional axial extended tubular pump with different blade angles

Methodical and algorithmic aspects of mathematical modeling of a screw aircraft power plant

The article describes the solution of a scientific problem that consists in expanding the functionality of the program “Calculation of the traction-economic and mass-specific characteristics of the power plant and aircraft motion parameters” through the introduction of additional algorithms and mathematical models for calculating the altitude-speed characteristics of screw aircraft power installations. At the same time, an internal calculation of the aircraft propeller thrust is used according to experimental aerodynamic coefficients, which makes it possible to increase the efficiency and reliability of complex theoretical studies of power plants of various types as part of aircraft at the stage of external design. A description is given of the developed algorithms: an algorithm for converting power on the output shaft of a gas turbine engine into thrust of an aircraft power plant; a mathematical model of a propeller that provides calculation of its thrust from experimental aerodynamic coefficients; an algorithm for determining the thrust of the power plant, taking into account the compressibility of the air and the interaction of the propeller and the elements of the airframe of the aircraft. Some features of the mathematical modeling of an aircraft propeller are revealed, in particular, the principle of propeller control by influencing the blade angle and rotational speed depending on the aircraft flight speed and a method for constructing the field of aerodynamic characteristics of an aircraft propeller in a wide range of blade angle and speed coefficient. In conclusion, the results of verification of the modified program are presented with an analysis of the obtained altitude-speed characteristics.

Energy-saving mechanism and dynamic characteristics of blade angle adjustment in low head pumping system

To investigate the energy-saving mechanisms and dynamic characteristics of blade angle adjustment, this study proposes a novel research method via simulations, prototype and model testing. For stable conditions, the internal field, the external and energy characteristics of the pumping system with different blade angle are examined. The dynamic characteristics of the pumping system and the blade force characteristics during the adjustment process are also studied. The research results show that, under a certain net head, an appropriate impeller blade angle improves the flow state in the pump and conduits, decreasing the entropy production and providing suitable inlet circulation to reduce the hydraulic loss of outlet conduit, thereby improving the pumping system efficiency by 5–10 percentage points. During the adjustment process, there is an approximate 20-s delay in dynamic characteristics. Additionally, with the increase of the blade angle, the hydraulic torques for blade axis and pump shaft increase, thus increasing the blade adjustment force and shaft power. The adjusting force is found to be underestimated in the adjustment processes of decreasing the blade angle. Achievements of this paper contribute to high efficiency of pumping system and high reliability of blade adjustment devices and pump units.

Fast predesign methodology of centrifugal compressor for PEMFCs combining a physics-based loss model and an interpretable machine learning method

For boosted hydrogen fuel cells, the centrifugal compressor greatly affects the system's efficiency, stack power and costs. However, the design of the centrifugal compressor is a lengthy and high-cost process. To tackle this issue, a new method combining a physics-based loss model and a machine learning method was proposed to achieve a fast and more accurate preliminary design step. A high-precision physics-based loss model was developed and validated for data generation. Furthermore, two gradient boosting decision tree (GBDT) models with Bayesian hyperparameter turning were established to construct mapping relationships between geometric parameters and aerodynamic performance. Then, the Sobol sensitivity analysis and Shapley Additive Explanations (SHAP)-based interpretability were used to explore the impact of the geometric parameters on the aerodynamic performances. Results showed that the outlet blade angle, impeller outlet diameter, impeller outlet width, inducer shroud diameter, and inducer blade angle (at the shroud) were the five most sensitive parameters. Additionally, some practical design recommendations were extracted using SHAP-based interpretability. The isentropic efficiencies of two redesign cases with optimal geometric parameters were increased by 2.59% and 1.85% compared with the baseline impellers. The performance prediction was completed within a time of 6 s using the proposed new predesign method. This study represents a significant new attempt to advance the preliminary design methodology of centrifugal compressors.