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1
Li, Yan, Chang Zhao, Chunming Qu, Shouyang Zhao, Fang Feng e Kotaro Tagawa. "Effect of Auxiliary Blade on Aerodynamic Characteristics of Vertical Axis Wind Turbine by Numerical Simulation". International Journal of Rotating Machinery 2019 (21 aprile 2019): 1–17. http://dx.doi.org/10.1155/2019/8098160.
Testo completoAbstract (sommario):
In order to improve the aerodynamic characteristics of the Straight-bladed Vertical Axis Wind Turbine (SB-VAWT), a rotor structure with auxiliary blade installed behind the main blade was proposed in this study. To investigate the effects of relative thickness and the fixing angle of the auxiliary blade on aerodynamic characteristics of SB-VAWT, numerical simulations were carried out. Two shapes of NACA 4-digital series blade-section, NACA0018 and NACA0024, were selected as the main blades in this work. Effects of relative thickness and fixing angles of auxiliary blade on the aerodynamic performance of SB-VAWT had been analyzed in detail, which had 5 kinds of relative thickness and 3 kinds of fixing angles combined into 13 working conditions. And the main blades and the auxiliary blades were also decided as the NACA series airfoil with five kinds of relative thickness. Three kinds of fixing angle of auxiliary blade installed behind main blade were used including 0°, 5°, and 10°. The simulations included the output power coefficients, the static torque coefficients, and the flow fields around the main blade and auxiliary blade for both the dynamic and static conditions at some typical azimuth angles. The results show that the auxiliary blade with certain relative thickness and fixing angle can improve the output power characteristics and static torque characteristics of SB-VAWT, which can also provide research reference for improving the performance of VAWT.
2
DEDA ALTAN, Burcin. "Enhancement of the performance of vertical axis wind rotors with straight blades". European Mechanical Science 7, n. 2 (20 giugno 2023): 49–55. http://dx.doi.org/10.26701/ems.1246352.
Testo completoAbstract (sommario):
In this study, it has been aimed to improve the performance of vertical axis wind rotors with straight blades. For this purpose, an additional performance-enhancing setup has been used, placed in front of the vertical axis wind rotor with straight blades, in order to increase the performance. The effects on the rotor performance increase have been investigated numerically by keeping the dimensions of this performance-enhancing additional setup constant, by changing the number of blades of the straight bladed rotor and by changing the blade angles if the straight blades have been angled. Numerical analyzes performed in this study have been validated by experimental literature data. After creating the solid models required for the rotor performance analysis, the computational fluid dynamics (CFD) program ANSYS Fluent has been used. Here, studies have been carried out with two, three and four bladed rotors as the number of blades. As the blade angle, the effects of the angles between 180 and 120 have been examined. As a result of the study with the additional performance setup (APS), it has been determined that the optimum performance has been obtained with the vertical axis rotor with three blades and 150 blade angle. As a final result, it has been determined that the power coefficient obtained from the optimum vertical axis rotor with additional performance setup increased approximately 2.6 times compared to the optimum rotor without setup.
3
Pribadyo, Pribadyo, Hadiyanto H e Jamari J. "Simulasi Performa Turbin Propeller Dengan Sudut Pitch Yang Divariasikan". Jurnal Mekanova: Mekanikal, Inovasi dan Teknologi 6, n. 1 (11 giugno 2020): 54. http://dx.doi.org/10.35308/jmkn.v6i1.2257.
Testo completoAbstract (sommario):
Propeller turbine performance can be improved by changing the turbine design parameters. One method that was developed is to vary the blade angle on the runner's blades. Analysis of the influence of blade angle on propeller turbine performance is done through numerical simulations based on computational fluid dynamics. The simulation is done with variations of propeller turbine blade angles of 180, 230, and 280 at flow rates of 0.08 m/s to 0.5 m/s. Simulation results show turbines with 250 blade angles have the best performance compared to turbine blade angles of 230 and 280. While the turbine blade angles of 230 tend to have higher performance compared to angles of 280 even though both have peak values for the corresponding power coefficient. Keywords—Propeller turbine, runner blade, pitch angle, CFD simulation
4
Thresher, R. W., A. D. Wright e E. L. Hershberg. "A Computer Analysis of Wind Turbine Blade Dynamic Loads". Journal of Solar Energy Engineering 108, n. 1 (1 febbraio 1986): 17–25. http://dx.doi.org/10.1115/1.3268046.
Testo completoAbstract (sommario):
The flapping motion of a single wind turbine rotor blade has been analyzed and equations describing the flapping motion have been developed. The analysis was constrained to allow only flapping motions for a cantilevered blade, and the equations of motion are linearized. A computer code, called FLAP (Force and Loads Analysis Program), to solve the equations of motion and compute the blade loads, has been completed and compared to measured loads for a 3-bladed downwind turbine with stiff blades. The results of the program are presented in tabulated form for equidistant points along the blade and equal azimuth angles around the rotor disk. The blade deflection, slope and velocity, flapwise shear and moment, edgewise shear and moment, blade tension, and blade torsion are given. The deterministic excitations considered in the analysis include wind shear, tower shadow, gravity, and a prescribed yaw motion.
5
Saowalak Thongdee, Churat Tararuk, Natthawud Dussadee, Rameshprabu Ramaraj e Tanate Chaichana. "Study on performance of a savonius wind turbines related with the blade angle". Maejo International Journal of Energy and Environmental Communication 1, n. 2 (9 agosto 2019): 32–36. http://dx.doi.org/10.54279/mijeec.v1i2.244916.
Testo completoAbstract (sommario):
This research aimed to compare the performance of Savonius vertical axis wind turbines through blade numbers and different blade angles. In this study, applicable turbines having 4, 6, 8, 12, 16 and 18 numbers of blades with the angles of the blades of -15°, -5°, 0°, 5° and 15°, respectively. The rotor used was a semicircle shaped blade made from PVC material and has a blade diameter of 6 cm and 30 cm for both rotor diameter and height. The turbine was tested deadweight range of 0-0.49 kg at 4 m/s wind speed. The results showed that the blade angle has a positive effect on increasing the power and torque coefficient of Savonius wind turbine, specifically on blades less than 16. The highest power and torque coefficient was obtained from the turbine having16 blades at an angle of 5°. This configuration also found that the maximum power and torque coefficient in the tip speed ratio ranging from 0.3-0.4 are 0.2519 and 0.5858, respectively.
6
Wu, Kuo-Tsai, Kuo-Hao Lo, Ruey-Chy Kao e Sheng-Jye Hwang. "Numerical and Experimental Investigation of the Effect of Design Parameters on Savonius-Type Hydrokinetic Turbine Performance". Energies 15, n. 5 (2 marzo 2022): 1856. http://dx.doi.org/10.3390/en15051856.
Testo completoAbstract (sommario):
To meet the increased demand of hydroelectric power generation, a novel drag-based Savonius turbine with the characteristics of a simpler fabrication process and good starting characteristics is designed, fabricated, and analyzed. The newly designed turbine is suitable to be installed in rivers, irrigation channels, ocean currents, etc., for small-scale hydroelectric power generation. In the present study, experiments are carried out to investigate the influence of the design parameters of this turbine on its power performance in order to improve its efficiency, including blade arc angles (180°, 135°), blade placement angles (0°, ±22.5°), and the number of blades (2, 3, 6, and 8). Further, three-dimensional CFD simulations are performed with Re = 6.72×105, matching the experimental conditions, in order to study the changes in the flow field and the rotation characteristics of the turbine. The research results indicate that a six-bladed turbine with a blade arc angle of 135° and a blade placement angle of 0° has higher torque and better power performance, which makes it the most suitable design when also considering cost. Furthermore, it was found that an increase in the number of turbine blades contributes to improving the performance of the turbine. The maximum power coefficient is 0.099 at a tip speed ratio of 0.34.
7
Li, Xin-kai, Jin-xue Guo, Xiao-ming Chen, Ke Yang, Tian-yu He e Xiao-dong Wang. "Experimental and Numerical Analysis of the Effect of a New Lightning Protection System on Lightning Protection and Aerodynamic Noise Performance of Wind Turbine Blades". Electronics 8, n. 9 (12 settembre 2019): 1020. http://dx.doi.org/10.3390/electronics8091020.
Testo completoAbstract (sommario):
In order to tackle the problem of the high failure rate of blades of large wind turbine units due to lightning damage, a new lightning protection system (NLPS) for wind turbine blades is proposed based on the lightning damage mechanism of blades. Firstly, 10 high-voltage discharge tests are performed for blades with and without the NLPS to study the effect of lightning protection. The results show that when the surface of the blade without the NLPS is struck by lightning 10 times, the damage rate of the blade is 100%; for the blade with the NLPS and the lightning attachment position is always on the NLPS in 10 discharge tests, the damage rate of blades is 0% and the lightning protection rate of blades is 100%, indicating that the lightning protection effect for blades with the NLPS is greatly improved. Moreover, the static electric fields of the blades with and without the NLPS are calculated. The results show that the NLPS can shield the electric field around the lower lead wire of the blade, thus effectively reducing the electric field intensity. The NLPS initiates the upward leader more easily than the lower lead wire; therefore, the lightning attachment point is located on the NLPS, thus protecting the blade. Secondly, the aerodynamic and aero-noise characteristics of the blade with and without the NLPS are calculated. The results indicate that the NLPS has little influence on the aerodynamic performance of the blade but has some influence on the aero-noise of the blade. The aero-noise of the airfoil can be reduced at angles of attack of 4°, 8°, 11°, and 15°, but the influence of different phase angles of the airfoil on the amplitude of the sound pressure level (SPL) varies. The aero-noise of the airfoil with the NLPS decreases by 16% and 8% at angles of attack of 4° and 8°, respectively. In general, the design of the NLPS reaches the desired requirements, but it still needs to be further optimized in combination with the blade manufacturing process.
8
Yan, Jing, Xiaobing Liu, Li Peng e Jianan Li. "A new design way for cylindrical blades with adjustable inlet blade angles". Advances in Mechanical Engineering 11, n. 6 (giugno 2019): 168781401983017. http://dx.doi.org/10.1177/1687814019830174.
Testo completoAbstract (sommario):
A new approach for cylindrical blade design is presented in this article. Authors of this article analyzed the main reasons which are responsible for the low efficiency of untwisted blades and found out that the shock losses along the blade leading edge are much higher than those of twisted blades. Furthermore, based on the analysis, this article proposed a new design approach that is different from the traditional one. This new approach can reduce hydraulic losses at blade leading edge and improve performance and efficiency of cylindrical blades. In the traditional design process, to draw blade projection in plan view, an incidence at intersection of blade leading edge and inner streamline on the meridional section is selected for calculating blade inlet angle accurately. Because the incidence and the blade inlet angle at the intersection of blade leading edge and outer streamline are formed automatically, the blade inlet angles at this point are not suitable for oncoming flow direction, generating noticeable shock losses at this place. In the new design program, blade inlet angles at both intersection points formed by blade leading edge and the outer, inner streamlines are accurately calculated. This makes the shock losses generated by blade leading edge be minimized. Moreover, in conventional design, the projection of blade pressure side into plan view consists of only one plane curve. In the new design way, projection of blade surface in plan view is composed of two curves joined smoothly and continuously. Two impellers with fundamentally identical geometrical parameters were designed and manufactured, and the only difference is that their cylindrical blades were calculated and configured by applying a traditional design method or a the new approach. Test findings from an open loop indicate that in a wide load range from 0.8 to 1.2 times design flow rate, both head and efficiency of the new pump were raised. Over the operating range, efficiency of the new pump increased by 0.5% to 2.7%. Particularly, for higher flow rate, pump performance was improved significantly, and the increase of efficiency at pump design point arrived at 2.7%. The results suggest that the new approach presented in this article offers an effective and useful means to improve performance of low specific speed pumps.
9
Li, Yan, Fang Feng, Wen Qiang Tian e Kotaro Tagawa. "Numerical Simulation on the Static Torque Performance of Vertical Axis Wind Turbine with Different Blade Airfoils". Applied Mechanics and Materials 84-85 (agosto 2011): 702–5. http://dx.doi.org/10.4028/www.scientific.net/amm.84-85.702.
Testo completoAbstract (sommario):
Recently, the straight-bladed vertical axis wind turbine (SB-VAWT) receives more and more attentions for its simple design, low cost, and good maintenance. The torque performance of the SB-VAWT is greatly affected by the blade airfoil. In order to research the static torque characteristics of SB-VAWT with symmetrical and non-symmetrical blade airfoil, numerical simulations by 2D CFD method were carried out on three kinds of blade airfoils including NACA0018, NACA2418 and NACA4418 at different azimuth angles. Furthermore, the static torque coefficient of the SB-VAWT with four blades with the three kinds of blade airfoils was calculated. The pressure and velocity fields were also obtained to analyze the static torque performance. Based on these results, the effects of blade airfoils on the starting torque performance of the SB-VAWT were compared and discussed.
10
Tao, Yi, Yongming Bai e Yingchun Wu. "Influence of Blade Thickness on Solid–Liquid Two-Phase Flow and Impeller Wear in a Ceramic Centrifugal Slurry Pump". Processes 9, n. 8 (21 luglio 2021): 1259. http://dx.doi.org/10.3390/pr9081259.
Testo completoAbstract (sommario):
The impeller blades of ceramic slurry pumps are usually very thick for the purpose of prolonging the service life. In this paper, numerical simulations and wear test were conducted to investigate the influence of blade thickness on the solid–liquid two-phase flow and impeller wear in a ceramic centrifugal slurry pump. The wear test was conducted for CFD validation. The numerical results show that the incident angles of solid particles increase with increasing blade thickness, which results in larger wrap angles of the solid particle trajectories. The increasing wrap angles of the solid particle trajectories offset the region that the collisions between the blade pressure side and the solid particles side take place towards the impeller exit and lead to more impacts between the solid particles and the blade suction side. The numerical results are in good accordance with the wear pattern of the tested impellers, which demonstrates that the numerical method adopted in this paper is predictable in the abrasion of the impeller of a ceramic centrifugal slurry pump. The experimental results show that an increase in the blade thickness alleviates the abrasion of the leading edges and the pressure side of the impeller blades; however, it also aggravates the abrasion of the blade suction side and decreases the pump performance.
11
Balalaieva, Kateryna, Anton Balalaiev, Grygoriy Golembiyevskyy e Artem Kovtun. "Характеристики повітряного гвинта квадрокоптера". Aerospace Technic and Technology, n. 4sup1 (24 agosto 2023): 23–28. http://dx.doi.org/10.32620/aktt.2023.4sup1.04.
Testo completoAbstract (sommario):
The subject of the study is the characteristics of the quadrocopter propeller. The object of the study is a two-blade propeller of a quadrocopter. The aim of this study was to evaluate the efficiency, acoustic characteristics of the propeller of a quadrocopter and optimize the angles of laying out carbon fiber with minimization of deflection. To achieve this goal, the following tasks were solved: simulation of the flow in a two-blade propeller of a quadrocopter in a given range of rotation frequencies; calculation of the efficiency of a two-blade propeller of a quadrocopter; calculation of the level of acoustic pressure of the studied propeller; and calculation of the deflection of a two-blade propeller of a quadrocopter at different angles of carbon laying out. The study of the flow in the propeller was carried out using the method of numerical experiment. The calculation for the deflection was carried out on the basis of the aerodynamic characteristics of the propeller using the method of a numerical experiment. The level of acoustic pressure L was estimated at 1 m from the source of acoustic radiation (screw). Results: the optimal mode of operation with a maximum efficiency is observed at a speed of 9000 rpm. and reaches a value of 0.853. At the minimum investigated speed of 3000 rpm. The propeller efficiency has the lowest value and is 0.638. With an increase in the speed of the rotor of the engine, the efficiency of the propeller gradually increases. With the increase of rotational speed from 9000 rpm. up to 10000 rpm. the efficiency decreases from 0.853 to 0.833. Estimation of the level of acoustic pressure of the studied two-bladed propeller showed that the rotation frequency had a significant effect on the level of acoustic pressure of the propeller. With an increase in rotational speed from 3000 rpm. up to 10000 rpm. propeller acoustic pressure-level increases from 56.62 dB to 90.57 dB. The calculation results showed that the deflection of the propeller blades under study depends on the laying angles of the carbon fiber layers. Blade deflection varies from 0.76 mm to 0.821 mm. The greatest deflection of the blades was achieved with the option of laying out layers of carbon fiber 0°/30°, the smallest - at angles of 0°/80°. The scientific novelty and practical significance of the conducted research is that new data on the characteristics of a two-blade quadrocopter propeller have been obtained. The data obtained will help create and optimize the parameters of a two-bladed quadrocopter propeller.
12
Duquette, Matthew M., Jessica Swanson e Kenneth D. Visser. "Solidity and Blade Number Effects on a Fixed Pitch, 50 W Horizontal Axis Wind Turbine". Wind Engineering 27, n. 4 (agosto 2003): 299–316. http://dx.doi.org/10.1260/030952403322665271.
Testo completoAbstract (sommario):
Experimental studies were conducted on a modified Rutland 500 horizontal axis wind turbine to evaluate numerical implications of solidity and blade number on the aerodynamic performance. Wind tunnel data were acquired on the turbine with flat-plate, constant-chord blade sets and optimum-designed blade sets to compare with theoretical trends, which had indicated that increased solidity and blade number more than conventional 3-bladed designs, would yield larger power coefficients, CP. The data for the flat plate blades demonstrated power coefficient improvements as the range of solidities was increased from 7% to 27%, but did not indicate performance gains for increased blade numbers. It was also observed that larger pitch angles decreased the optimum tip speed ratio range significantly with a small (5% or less) change in maximum CP. The optimum-design 3-bladed rotors produced an increased experimental CP as solidity increased, with reduced tip speed ratio, at the optimum operating point. As blade number was increased at a constant solidity of 10% from 3 to 12 blades, aerodynamic efficiency and power sharply decreased, contrary to the numerical predictions and the flat plate experimental results. Low Reynolds numbers and wind tunnel blockage effects limit these conclusions and a full scale prototype rotor is being constructed to examine the results of the numerical and experimental studies using a side-by-side comparison with a commercially available wind turbine at the Clarkson University wind-turbine test site.
13
Nejad, J., A. Riasi e A. Nourbakhsh. "Efficiency improvement of regenerative pump using blade profile modification: Experimental study". Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, n. 3 (22 marzo 2018): 448–55. http://dx.doi.org/10.1177/0954408918763554.
Testo completoAbstract (sommario):
Regenerative flow pump is a kind of turbomachine with the ability to generate high heads at relatively low flow rates. Despite having low hydraulic efficiency, regenerative pumps have found many applications in industries due to their simplicity, compact size, low manufacturing costs, and low specific speed. In this paper, an experimental study has been carried out to investigate the influence of impeller blade change on the performance of regenerative pump. To this end, the straight radial blades were changed to curved blades with the same inlet/outlet angles. Three forward curved blade impellers as well as straight radial blade impeller were designed and manufactured. Since the regenerative pump comply with the affinity laws, the results of experimental tests were expressed in nondimensional coefficients. The results showed that by increasing the blade angle to 10°, the efficiency increased and at higher blade angles of 30° and 50°, the efficiency decreased for all flow conditions. The best angle was obtained about 15° by curve fitting to the experimental data at the design flow coefficient.
14
Shi, Lijian, Changxin Wu, Li Wang, Tian Xu, Yuhang Jiang, Yao Chai e Jun Zhu. "Influence of Blade Angle Deviation on the Hydraulic Performance and Structural Characteristics of S-Type Front Shaft Extension Tubular Pump Device". Processes 10, n. 2 (8 febbraio 2022): 328. http://dx.doi.org/10.3390/pr10020328.
Testo completoAbstract (sommario):
When the axial-flow pump is running, the blade angle is not fully adjusted or there are errors in the manufacture of the blades, which will lead to inconsistent blade placement angles during operation, and which will reduce the efficiency of the axial-flow pump. This paper uses the research methods of numerical simulation and model experiments to analyze the hydraulic performance and impeller structure characteristics of each flow components under different schemes when the angles of each blade of the S-type front shaft extension tubular pump device are inconsistent. The research phenomenon is that the guide vane greatly recovers the flow velocity circulation at the impeller outlet, reduces the hydraulic loss of guide vane, and widens the best efficiency range with an increase in guide vane blade angle. When the blade angle deviation occurs, the flow field of each blade channel affects each other, and the maximum decrease in the best efficiency is up to 7.78%, mainly due to the increased hydraulic loss in the outlet channel. The blade angle deviation will also affect the maximum equivalent stress and maximum deformation of the impeller, which is more obvious in large flow conditions. Inconsistent blade angles seriously affect the operating efficiency of the water pump and water pump device, and make the structural characteristics of the impeller worse.
15
Tangler, J. L. "Influence of Pitch, Twist, and Taper on a Blade’s Performance Loss due to Roughness". Journal of Solar Energy Engineering 119, n. 3 (1 agosto 1997): 248–52. http://dx.doi.org/10.1115/1.2888027.
Testo completoAbstract (sommario):
The purpose of this study was to determine the influence of blade geometric parameters such as pitch, twist, and taper on a blade’s sensitivity to leading edge roughness. The approach began with an evaluation of available test data of performance degradation due to roughness effects for several rotors. In addition to airfoil geometry, this evaluation suggested that a rotor’s sensitivity to roughness was also influenced by the blade geometric parameters. Parametric studies were conducted using the PROP93 computer code with wind tunnel airfoil characteristics for smooth and rough surface conditions to quantify the performance loss due to roughness for tapered and twisted blades relative to a constant-chord nontwisted blade at several blade pitch angles. The results indicate that a constant-chord nontwisted blade pitched toward stall will have the greatest losses due to roughness. The use of twist, taper, and positive blade-pitch angles all help reduce the angle-of-attack distribution along the blade for a given wind speed and the associated performance degradation due to roughness.
16
Chelabi, Mohammed Amine, Milan Saga, Ivan Kuric, Yevheniia Basova, Sergey Dobrotvorskiy, Vitalii Ivanov e Ivan Pavlenko. "The Effect of Blade Angle Deviation on Mixed Inflow Turbine Performances". Applied Sciences 12, n. 8 (8 aprile 2022): 3781. http://dx.doi.org/10.3390/app12083781.
Testo completoAbstract (sommario):
The choice of blades for mixed turbines is to achieve the required deflection with minimal losses. In addition, it is necessary that the blade functions without a detachment in a wide area outside the nominal operating point of the machine. In the blade profile study, it is required to satisfy the conditions relating to fluid mechanics and those relating to the possibility of realization of construction. The work carried out presents the effect of the blade deviation angle on the geometric blade shape and the performance of the mixed inflow turbine on keeping the same rotor casing in order to improve its performances. It was remarked that the efficiency is proportional to the deviation angle’s increase, but the rotor became heavy. It has been determined that the effect of the blade deviation angle on mixed inflow performances decreases dramatically starting from the angle −20° for a 100% of machine load. It was urged to avoid relying on angles greater than −20 as values for blade deviation angles. The study noted that the maximum obtained in the output work and power is related to the highest the efficiency for a specific optimum design case (−35° of deviation blade angle) due to the increase in the contact surface between the blade and the fluid, but the problem is that the rotor gets a little heavy (4.37% weight gain). Among recommendations, attention was given to the more significant absolute exit kinetic energies, for values of deviation blade angle between -10° and −20°, where an exhaust diffuser is recommended to use to recover a part of it into a greater expansion ratio. These simulation results were obtained using a CFD calculation code-named CFX.15. This code allowed for the resolution of the averaged dynamic equations governing the stationary, compressible, and viscous internal flow.
17
Khosravani, Ali, Jacky M. A. Desbiolles, Chris Saunders, Mustafa Ucgul e John M. Fielke. "Prediction of Single Disc Seeding System Forces, Using a Semi-Analytical and Discrete Element Method (DEM) Considering Rotation Effects". Agriculture 13, n. 1 (13 gennaio 2023): 202. http://dx.doi.org/10.3390/agriculture13010202.
Testo completoAbstract (sommario):
Disc seeders are commonly used in no-till farming systems, and their performance evaluation generally rely on expensive and time-consuming field experiments. Mathematical models can help speed up force-related evaluations and improve the understanding of soil-disc interactions, to assist the performance optimisation processes. Previous analytical force prediction models of disc blades have not accounted for the free rotation aspect of the disc blade. This paper develops an analytical force prediction model from the wide blade failure theory adapted to suit rotating flat disc blades operating at different sweep and tilt angles and compares predictions with Discrete Element Method (DEM) simulations. To validate the two models, experiments were performed on a remoulded sandy soil condition using a rotating flat disc set at two tilt angles of 0° and 20°, and four sweep angles of 6, 26, 45 and 90° the 3-dimensional force components of draught, vertical and side forces were measured. Results showed a higher coefficient of determination (R2 = 0.95) was obtained with analytical model predictions compared to DEM predictions (R2 = 0.85) for their agreement with the test results. It was found that both the developed analytical approach and the DEM model can be used to predict tillage forces at different sweep and tilt angles acting on a rotating flat disc blade.
18
Nishi, Yasuyuki, e Junichiro Fukutomi. "Component Analysis of Unsteady Hydrodynamic Force of Closed-Type Centrifugal Pump with Single Blades of Different Blade Outlet Angles". International Journal of Rotating Machinery 2015 (2015): 1–17. http://dx.doi.org/10.1155/2015/419736.
Testo completoAbstract (sommario):
Single-blade centrifugal impellers for sewage systems undergo both unsteady radial and axial thrusts. Therefore, it is extremely important for the improvement of pump reliability to quantitatively grasp these fluctuating hydrodynamic forces and determine the generation mechanism behind them. In this study, we conducted component analyses of radial and axial thrusts of closed, single-blade centrifugal pumps with different blade outlet angles by numerical analysis while considering leakage flow. The results revealed the effect of the blade outlet angle on the components of radial and axial thrusts. For increased flow rates, the time-averaged values of the pressure component were similar for all impellers, although its fluctuating components were higher for impellers with larger blade outlet angles. Moreover, the fluctuating inertia component of the impeller with a blade outlet angle of 8° decreased as the flow rate increased, whereas those with 16° and 24° angles increased. Therefore, the radial thrust on the hydraulic part was significantly higher for impellers with high blade outlet angles.
19
Wang, Shi Ming, e Ka Tian. "Flow Field Numerical Simulation Analysis of Five Wing Horizontal Wave Turbine Power Plant with Different Blade Angles". Applied Mechanics and Materials 477-478 (dicembre 2013): 221–25. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.221.
Testo completoAbstract (sommario):
Used FLUENT software to simulate the flow distribution of a certain horizontal turbine with its blade angle changed from 25 ° to-35 °.The simulation results show the flow field changes with a period which was a fifth to the turbine rotational period. When the blade heads deflected laterally, the high flow velocity appeared near rear back turbine blades, or it appeared near the facing flow blades which were in the front lower part of the turbine. Besides, for blade angle deflected inside models, a stable annular velocity vector vortex gradually emerged around turbine as blade angle increased. The maximum velocity of flow field increased firstly and then stayed stable as blade angle changed. The flow distribution results fully confirmed that the reasonable optimization to the blade angle of the turbine can help the turbine achieve a more effective rotation and improve the flow distribution.
20
Fang, Peng, Jianjun Du e Shunzhou Yu. "Impeller (straight blade) design variations and their influence on the performance of a centrifugal blood pump". International Journal of Artificial Organs 43, n. 12 (20 aprile 2020): 782–95. http://dx.doi.org/10.1177/0391398820913559.
Testo completoAbstract (sommario):
Introduction: The miniaturization of blood pumps has become a trend due to the advantage of easier transplantation, especially for pediatric patients. In small-scale pumps, it is much easier and more cost-efficient to manufacture the impeller with straight blades compared to spiral-profile blades. Methods: Straight-blade impeller designs with different blade angles, blade numbers, and impeller flow passage positions are evaluated using the computational fluid dynamics method. Blade angles (θ = 0°, 20°, 30°, and 40°), blade numbers ( N = 5, 6, 7, and 8), and three positions of impeller flow passage (referred to as top, middle, and bottom) are selected as the studied parametric values. Results: The numerical results reveal that with increasing blade angle, the pressure head and the hydraulic efficiency increase, and the average scalar shear stress and the normalized index of hemolysis decrease. The minimum radial force and axial thrust are obtained when θ equals 20°. In addition, the minimum average scalar shear stress and normalized index of hemolysis values are obtained when N = 6, and the maximum values are obtained when N = 5. Regarding the impeller flow passage position, the axial thrust and the stagnation area forming in the impeller eye are reduced as the flow passage height declines. Conclusion: The consideration of a blade angle can greatly improve the performance of blood pumps, although the influence of the blade number is not very easily determined. The bottom position of the impeller flow passage is the best design.
21
Gölcü, M., N. Usta e Y. Pancar. "Effects of Splitter Blades on Deep Well Pump Performance". Journal of Energy Resources Technology 129, n. 3 (18 gennaio 2007): 169–76. http://dx.doi.org/10.1115/1.2748810.
Testo completoAbstract (sommario):
Impellers with splitter blades have been used in turbomachinery design for both pumps and compressors. Increasing the number of blades increases the head of the pump, however, it causes a decrease in efficiency due to the blockage effect of the blade thickness and friction. The impellers with splitter blades between two long blades can be used to alleviate the serious clogging at the inlet of the impeller caused by more blades. In this study, impellers having a different number of blades (z=3, 4, 5, 6, and 7) with and without splitter blades (25, 35, 50, 60, and 80% of the main blade length) were tested in a deep well pump. The effects of the main blade number and lengths of splitter blades on the pump performance have been investigated. While the number of main blades and the lengths of the splitter blades of a principal impeller were changed, the other parameters such as pump casing, blade inlet and outlet angles, blade thickness, impeller inlet and outlet diameters, were kept the same.
22
Zhang, Hui Min, e Hui Liang Liao. "Structure Optimization of Open Turbine Type Agitator". Advanced Materials Research 1082 (dicembre 2014): 284–87. http://dx.doi.org/10.4028/www.scientific.net/amr.1082.284.
Testo completoAbstract (sommario):
Regarding open turbine type agitator, CFD method was used to simulate the mixing flow field with different number of blades, different blade angles and different ratio of blade lengths and diameters. In addition, according to the mixing effect, the parameters of agitator structure are optimized. Numerical simulations are verified by PIV experiments. The Multiple reference frame model conforms to the reality. Agitator structure is optimized when the ratio of blade length and diameter is 0.74, the blade angle is 45 °,blade number is 6, leading to the best the mixing effect with least stirring dead areas.
23
Islamova, O. V., A. Z. Tokov e F. A. Ataeva. "Energy efficiency is the most important indicator of the quality of food grinders". Proceedings of the Voronezh State University of Engineering Technologies 81, n. 2 (1 novembre 2019): 56–62. http://dx.doi.org/10.20914/2310-1202-2019-2-56-62.
Testo completoAbstract (sommario):
A brief analysis of the methods of grinding technological raw materials from the standpoint of energy efficiency has been performed. Studies show that cutting (grinding) the feedstock into pieces of a certain size is the most energy-intensive. Existing designs of cutting elements of grinding mechanisms (cutting blade, cutting edge) are not optimal from the standpoint of energy efficiency. For example, the cutting blade in the working hole has a taper angle of 90°, and the taper angle of the cutting blade on the blades of the movable knife is also in the range of 80–90°. It is proposed to make the sharpening angles of the cutting blades on the blades of a movable knife equal to 5–8°. In addition, the blades of such a knife should have the shape of a classic wedge in all cross sections. Reducing the angle of sharpening of the cutting blade in the working hole of the grill to such values does not succeed in terms of design features (in particular, without violating transparency indicators). The reserves of reducing the angle of sharpening of the cutting blade in the working hole are shown (this angle can be less than 90°). The performed studies indicate that the smaller the energy costs for grinding the feedstock, the less it is rubbed and squeezed out of the holes of the grate. It can be assumed that the organoleptic properties did not deteriorate after grinding (but remained). The lower the transparency of the lattice, the grinding process is more energy-consuming. The smaller the sharpening angles of the cutting blades of the knives, the more energy-efficient the grinding process. The worse the quality of the crushed raw materials, for example, meat, which is characterized by the excessive presence of connective and cartilage tissues, films, etc., the more energy-efficient is the grinding process with knives with cutting blades with minimal sharpening angles.
24
Peczkis, Grzegorz, Piotr Wiśniewski e Andriy Zahorulko. "Experimental and Numerical Studies on the Influence of Blade Number in a Small Water Turbine". Energies 14, n. 9 (2 maggio 2021): 2604. http://dx.doi.org/10.3390/en14092604.
Testo completoAbstract (sommario):
This paper demonstrates the procedure of blade adjustment in a Kaplan-type water turbine, based on calculations of the flow system. The geometrical adjustment of a twisted blade with varying chord length is described in the study. Computational fluid dynamics (CFD) analysis was used to characterise aerofoil and turbine performance. Furthermore, two turbines, with a different number of blades, were designed, manufactured, and tested experimentally. The numerical model results were then compared with the experimental data. The studies were carried out with different rotational velocities and different stator blade incidence angles. The paper shows a comparison of the turbine efficiencies that were assessed, using numerical and experimental methods, of a flow system with four- and five-bladed rotors. The numerical model results matched up well with those of the experimental study. The efficiency of the proposed turbines reached up to 72% and 84% for four-bladed and five-bladed designs, respectively. These efficiencies, when considered with the turbine’s simplicity, low production and maintenance costs, as well as their potential for harvesting energy from low energy flows, mean that Kaplan turbines provide a promising technology for processing renewable energy.
25
Hsieh, W. C., J. M. Miao, C. C. Lai e C. S. Tai. "Experimental Study on Performance of Vertical Axis Wind Turbine with NACA 4-Digital Series of Blades". Advanced Materials Research 488-489 (marzo 2012): 1055–61. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.1055.
Testo completoAbstract (sommario):
The experimental studies of output power performances of a vertical-axis-wind-turbine (VAWT) had been conducted in suction-type low speed wind tunnel with various free stream velocity. Torque and rotation speed of blades were measured by using torque meter and optical detector to analyze the effect of blade-section shape on the performance of wind turbine. The test model of experiments in the research was H-rotor VAWT. Three shapes of the NACA 4-digital series blade-section, NACA0022, NACA6404, and NACA6422 were taken in this work. Effects of thickness and camber of blade-section, blade numbers, and blade setting angles on the performance of VAWT have been analyzed in detail. The results show that NACA6422 blade-section has rotation speed of 42% higher than that of NACA0022 when the free stream velocity is below 12 m/s and the blade numbers are 4-blade type. Wind turbines with NACA6422 blades also showed that about 10% higher output power than that of NACA0022 blades among the tested range of free stream velocity. Results indicated that wind turbine with blades of anti-symmetric and thick blade-section was generally more suitable for applying to VAWT. All results of this study can be used the optimization design of VAWT blades in further.
26
Ueshiba, Shingo, Keiji Ogi, Yutaka Shigematsu e Kei Saito. "Characterization of Machining Damages Generated by a Piercing Process in CFRP Laminates". Key Engineering Materials 656-657 (luglio 2015): 185–90. http://dx.doi.org/10.4028/www.scientific.net/kem.656-657.185.
Testo completoAbstract (sommario):
This paper presents experimental examples of machining damages resulting from a piercing process in CFRP laminates. A circular perforation was formed in CFRP cross-ply specimen with a punch jig using different blade angles and two distinct dimensional conditions. Surface, cross-sectional, and internal changes to the CFRP specimens after the hole-punching were observed using optical microscopy and X-ray analysis to quantitatively evaluate damage, including delamination, around the perforation area. Results indicate that the optimum piercing is achieved when the blades are parallel to fiber direction at an elevated temperature with blade angles essentially irrelevant.
27
Li, Junjie, Yunfeng Lou, Gaoyuan Yu, Tong Li e Xianlong Jin. "Effect of Bird Yaw/Pitch Angles on Soft Impact Damage of a Fan Assembly". Complexity 2021 (16 gennaio 2021): 1–13. http://dx.doi.org/10.1155/2021/8879874.
Testo completoAbstract (sommario):
This paper presents a numerical investigation of bird attitude angles affecting the soft-impact damage of a full fan assembly. Firstly, considering the geometry of a mallard, a real bird model is established by the Smoothed Particle Hydrodynamics (SPH) method and calibrated with available test data. Then, complying with airworthiness requirements, simulations of a full-bladed fan assembly subjected to a real bird were conducted to determine the critical ingestion parameters (CIP). Furthermore, a real bird with different attitude angles aimed at a full fan assembly was simulated. Results show that attitude angles of the bird produce a significant impact on the effect of the bird strike on rotating blades and would increase the possibility of blade failures, especially for the yaw angle of -45° and the pitch angle of −60°. It is invaluable for commercial airlines and engine manufactures to provide safe flight and landing by adopting the real bird model with critical yaw and pitch angles in the design for resistance to bird ingestion.
28
Santoso, Budi, Dominicus Danardono Dwi Prija Tjahjana e Purwadi Joko Widodo. "Performance Evaluation of Axial Flow Wind Turbine Integrated with The Condenser". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 76, n. 3 (29 ottobre 2020): 85–91. http://dx.doi.org/10.37934/arfmts.76.3.8591.
Testo completoAbstract (sommario):
This study investigated the application of an axial flow wind turbine integrated with a condenser. The exhaust air from condenser was used to drive the wind turbine by a ducted turbine system. There were two parameters varied in this work: the blade number and the blade pitch angle. The blade number used was two blades, five blades, and ten blades, while the blade pitch angles were 5°, 10°, 15°, 20°, 30°, and 45°. The diameter of the wind turbine was 495 mm. The model of the condenser had a fan diameter of 600 mm and the range of the average air velocity of 2.01 m/s - 7.86 m/s. The maximum mechanical power was 10.72 W for air velocity of 7.86 m/s. The maximum power coefficient recorded was 0.38 for the tip speed ratio of 1.3 on the blade number of five blades and a pitch angle of 10°. The maximum exhaust air energy recovery was 13.64% of the power consumption of the condenser fan.
29
ZHOU, Q., J. XIE, B. FANG e Y. PAN. "PARAMETRIC STUDY OF PROPELLER TONE NOISE DUE TO NONUNIFORM FLOWS". Journal of Computational Acoustics 21, n. 03 (3 luglio 2013): 1350005. http://dx.doi.org/10.1142/s0218396x13500057.
Testo completoAbstract (sommario):
This paper investigates the tone noise generation by submarine propellers operating in nonuniform flows. A frequency domain numerical approach is proposed. The flow nonuniformities due to submarine wakes are obtained from Computational Fluid Dynamics method. The results show that the velocity field and its harmonics depend greatly on the hull geometry and its appendages. The prediction of the radiated far-field tone noise due to a seven-bladed, highly-skewed propeller has been performed. A prediction of the acoustic pressure level for various blade skew angles shows that the tone noise reduction amount increases as the inflow velocity increases. The predicted dependence of the radiated noise on the inflow velocity, propeller diameter and blade rotational speed shows that the mean square sound pressure at the first-order blade passing frequency varies as the 3.3 power of the characteristic inflow velocity, the third power of the propeller diameter and with the second power of the blade rotational speed. Effects of blade number on the propeller tone noise directivity are also discussed, which shows that the characteristic coupling order between the main inflow harmonic and the rotating blades is the key to determine the directivity pattern.
30
Davies, M. R. D., e P. J. Bryanston-Cross. "Holographic Measurements and Theoretical Predictions of the Unsteady Flow in a Transonic Annular Cascade". Journal of Engineering for Gas Turbines and Power 107, n. 2 (1 aprile 1985): 450–57. http://dx.doi.org/10.1115/1.3239748.
Testo completoAbstract (sommario):
A series of measurements have been made on a transonic annular cascade. The cascade which represents the tip section of a compressor fan blade has an inlet Mach number of 1.18. By the use of external vibrators it is possible to vibrate the blades independently in torsion simulating different interblade phase angles in order to gain an understanding of shock movement and blade loading. The results presented are made over interblade phase angles of 180 and 135 deg at a blade frequency parameter of 0.1, based on chord. The holographic data obtained shows detail of shock movement during the cycle using a miniature holocamera located within the hub of the cascade. Unsteady sidewall pressure measurements have also been obtained over the vibration cycle. The data obtained have been compared with finite element calculations.
31
Chen, Kun Nan, e Wei Hsin Gau. "Structural Optimization on Composite Blades of Large-Scale Wind Turbines". Applied Mechanics and Materials 284-287 (gennaio 2013): 958–62. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.958.
Testo completoAbstract (sommario):
Turbine blades used in large-scale, horizontal-axis wind turbines are usually made from composite materials to reduce the weight while attaining a reasonable strength to weight ratio. The design of large wind turbine blades must consider both their aerodynamic efficiency and structural robustness. This paper presents an optimum design scheme for composite wind turbine blades. The first optimization phase produces the aerodynamic outer shape of a blade framed by airfoils with optimum cord lengths and twist angles along the blade spanwise direction. The second phase provides optimal material distribution for the composite blade. Loadings on the blade are simulated using wind field and wind turbine dynamics codes. The maximum loads on the turbine blade are then extracted and applied to a parameterized finite element model. A design example of a 3 MW wind turbine blade considering one critical load case with a mean wind speed of 25 m/s is demonstrated. The optimization result shows that although the initial blade model is an infeasible design, the optimization process eventually converges to a feasible solution with an optimized mass of 8750.2 kg.
32
Szczerba, Zygmunt, Piotr Szczerba, Kamil Szczerba, Marek Szumski e Krzysztof Pytel. "Wind Tunnel Experimental Study on the Efficiency of Vertical-Axis Wind Turbines via Analysis of Blade Pitch Angle Influence". Energies 16, n. 13 (23 giugno 2023): 4903. http://dx.doi.org/10.3390/en16134903.
Testo completoAbstract (sommario):
This paper presents results of experimental investigations and numerical simulations of a vertical-axis H-type wind turbine, considering the influence of propeller blade pitch angle on turbine characteristics. An innovative airfoil profile based on a modified symmetric NACA0015 airfoil profile was used as the designed blade profile, which was tested in a wind tunnel over a range of Reynolds numbers from 50,000 to 300,000. The phenomenon of angle-of-attack variation and the resulting forces acting on the blades, particularly in the horizontal configuration and vertical axis of rotation, were discussed. Series of experiments were conducted on a 1:1 scale four-bladed turbine model in the wind tunnel to determine the characteristics, specifically the power coefficient distribution over the tip speed ratio for various Reynolds numbers and blade pitch angles. Subsequently, the turbine was modeled using Qblade software, and a series of calculations were performed under the same conditions. The numerical results were validated with the experimental data.
33
Moustapha, S. H., G. J. Paron e J. H. T. Wade. "Secondary Flows in Cascades of Highly Loaded Turbine Blades". Journal of Engineering for Gas Turbines and Power 107, n. 4 (1 ottobre 1985): 1031–38. http://dx.doi.org/10.1115/1.3239807.
Testo completoAbstract (sommario):
Experimental measurements of the flow field in a low-speed, large-scale, annular cascade of highly loaded turbine rotor blades are presented. The blade has a turning angle of 128.5 deg, an aspect ratio of 0.88, and a Zweifel coefficient of 1. Detailed cascade tests consisted of inlet and exit flow parameter traverses, blade passage pressure distributions, and flow visualization. The results are presented in the form of contour plots and pitch-averaged radial distributions of losses and flow angles. The measurements are compared with the results obtained for the same blade section tested in a planar cascade. Distribution of the losses and flow angles revealed the presence of two large vortices that occupied a major portion of the trailing edge plane. A large high-loss core was visible in the center of the blade passage and coincided with regions of maximum flow underturning. The measured cascade secondary losses compared well with existing correlations.
34
Chen, Yiming, Ce An, Rongyong Zhang, Qiang Fu e Rongsheng Zhu. "Research on Two-Way Contra-Rotating Axial-Flow Pump–Turbine with Various Blade Angles in Pump Mode". Processes 11, n. 5 (18 maggio 2023): 1552. http://dx.doi.org/10.3390/pr11051552.
Testo completoAbstract (sommario):
In tidal two-way contra-rotating units, significant differences in performance often occur when arranging the front and rear impellers, which requires an optimized design of the impellers. To solve this problem, by reducing the blade inlet and outlet angles, the impact of different blade angles on the performance of two-way pump–turbines and the internal flow was explored, and the effects of the blade inlet angle of the impellers on the performance of the counter-rotating pump were obtained. Afterward, the streamline and vorticity of the two-stage impeller at different angles were analyzed. The results show that different blade angles will have a certain impact on the internal flow of the two-way pump–turbine. Different blade outlet angles have a significant impact. The variation in different inlet blade angles is not significant for the vorticity changes in the front impeller and rear impeller. In addition, changes in the outlet blade angle will have an impact on the location of LE impact water of the rear impeller, which in turn affects the contours of vorticity of the rear impeller near LE, which also means that the vorticity in this area is mainly dominated by the vortex stretching term.
35
Fazylova, Alina, Michail Malamatoudis e Panagiotis Kogias. "Optimization of the blade profile of a vertical axis wind turbine based on aerodynamic analysis". E3S Web of Conferences 404 (2023): 02002. http://dx.doi.org/10.1051/e3sconf/202340402002.
Testo completoAbstract (sommario):
This paper explores the influence of the angle of attack on the aerodynamic characteristics of the blade profile. The paper presents calculations, modeling and graphical representation of the blade shape during rotation around the axis. Using the given parameters, such as the length of the blade, the radius of the upper and lower boundaries, as well as the angle of inclination of the blade, the calculation of the coordinates of the points of the blade profile for various angles of rotation is given. The cross-sectional area, volume and mass of the blade were also calculated. Appropriate calculations were made to approximate the center of mass of the blade. To evaluate the influence of the angle of attack on the blade profile, the angles of attack were calculated for various angles of rotation.
36
Divakaran, Unnikrishnan, Ajith Ramesh, Akram Mohammad e Ratna Kishore Velamati. "Effect of Helix Angle on the Performance of Helical Vertical Axis Wind Turbine". Energies 14, n. 2 (12 gennaio 2021): 393. http://dx.doi.org/10.3390/en14020393.
Testo completoAbstract (sommario):
The energy crisis has forced researchers to look for various non-conventional energy sources. Wind energy is one of the potential sources, and researchers have invested resources in developing different kinds of wind turbines. Vertical axis wind turbines (VAWT) have received less attention than their horizontal-axis counterparts. A helical-bladed VAWT is preferred because it makes perfect sense as an improvement in design, as they have higher azimuth angles of power generation capabilities. This paper studies the effects of the helix angle of blades in the aerodynamic performance of VAWT using 3D numerical simulations. Three different helix angles of 60°, 90°, and 120° of a three-bladed VAWT operating across different tip speed ratios were studied. Turbulence is modelled using a four-equation transition SST k-ω model (shear stress transport). The 60° helical-bladed VAWT was found to be better performing in comparison with all other helical-bladed and straight-bladed VAWT. The ripple effects on the shaft are also analysed using a standard deviation plot of the moment coefficient generated by a single blade over one complete cycle of its rotation. It was observed that the greater the helix angle, the lower the standard deviation. The paper also tries to analyse the percentage of power generated by each quartile of flow and the contribution of each section of the blade. Ansys FLUENT was employed for the entire study. A comparative study between different helical-bladed VAWT and straight-bladed VAWT was carried out along with wake structure analysis and flow contours for a better understanding of the flow field.
37
König, Ronja, André Gerlach, Henry Schmidt e Eike Stumpf. "Experimental investigation on acoustics and efficiency of rotor configurations for electric aerial vehicles". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, n. 6 (1 agosto 2021): 323–34. http://dx.doi.org/10.3397/in-2021-1435.
Testo completoAbstract (sommario):
Aerial vehicles based on distributed electric propulsion systems have gained great interest. Their rotors however create loud and annoying sound, what obstructs market success. Variations in rotor configuration can be observed on emerging concepts, whereby the main varied parameters are blade radius, number of blades and blade distribution. The focus of this paper is to identify how these parameters can be chosen to optimize efficiency and acoustics, including psychoacoustic metrics and sound quality of single rotors while hovering. Results from experimental investigations done in a hover-test-bench are presented. Rectangular, symmetric blades are used. Experiments are done varying blade radius (61mm to 126 mm), number of blades (2 to 8) and blade distribution (equal and unequal angles). Acoustic measurements are analyzed regarding microphone position, sound pressure level, spectral characteristics, psychoacoustic metrics and selected sound quality models. Results show, that variations in blade radius, number of blades and blade distribution can improve efficiency and acoustics. Influence of these parameters on the acoustic signature at constant rotational speed and at constant thrust is discussed. Conclusions for optimized rotor design at aerial vehicles are derived and supplemented by resulting boundary conditions like building space and weight.
38
Bellary, S. A. I., Afzal Hussain, Abdus Samad e R. A. Kanai. "Performance Optimization of Centrifugal Pump for Crude Oil Delivery". Journal of Engineering Research [TJER] 15, n. 1 (1 febbraio 2018): 88. http://dx.doi.org/10.24200/tjer.vol15iss1pp88-101.
Testo completoAbstract (sommario):
Crude oil transport is an essential task in oil and gas industries, where centrifugal pumps are extensively used. The design of a centrifugal pump involves a number of independent parameters which affect the pump performance. Altering some of the parameters within a realistic range improves pump performance and saves a significant amount of energy. The present research investigated the pump characteristics by modifying the number of blades and the exit blade-angles. Reynolds-Averaged Navier-Stokes equations with standard k-ε two-equation turbulence closure were used for steady and incompressible flow of crude oil through the pump. The experimental set-up was installed and the pump performance calculated numerically was compared with the experiments. The investigations showed that the number of blades and the exit blade-angles have a significant influence on the head, shaft power, and efficiency. The vortical flow structures, recirculation and reverse flow characteristics around the impeller were investigated to explain the flow dynamics of impeller and casing. A larger number of blades on the rotor showed dominant streamlined flow without any wake phenomena. The combined effect of the number of blades and exit blade angle has led to an increase in head and efficiency through the parametric optimization.
39
Çiftci, Cihan, Ayşe Erdoğan e Mustafa Serdar Genç. "Investigation of the Mechanical Behavior of a New Generation Wind Turbine Blade Technology". Energies 16, n. 4 (16 febbraio 2023): 1961. http://dx.doi.org/10.3390/en16041961.
Testo completoAbstract (sommario):
Wind turbine blades are one of the largest parts of wind power systems. It is a handicap that these large parts of numerous wind turbines will become scrap in the near future. To prevent this handicap, newly produced blades should be recyclable. In this study, a turbine blade, known as the new generation of turbine blade, was manufactured with reinforced carbon beams and recycled, low-density polyethylene materials. The manufacturing addressed in this study reveals two novelties: (1) it produces a heterogeneous turbine blade; and (2) it produces a recyclable blade. In addition, this study also covers mechanical tests using a digital image correlation (DIC) system and modeling investigations of the new generation blade. For the mechanical tests, displacement and strain data of both new generation and conventional commercial blades were measured by the DIC method. Instead of dealing with the modeling difficulty of the new generation blade’s heterogeneity we modeled the blade structural system as a whole using the moment–curvature method as part of the finite element method. Then, the behavior of both the new generation and commercial blades at varying wind speeds and different angles of attack were compared. Consequently, the data reveal that the new generation blades performed sufficiently well compared with commercial blades regarding their stiffness.
40
Wright, T., e W. E. Simmons. "Blade Sweep for Low-Speed Axial Fans". Journal of Turbomachinery 112, n. 1 (1 gennaio 1990): 151–58. http://dx.doi.org/10.1115/1.2927413.
Testo completoAbstract (sommario):
The available literature on aerodynamic and acoustic properties of axial fans with swept blades is presented and discussed with particular emphasis on noise mechanisms and the influence of high-intensity inlet turbulence on “excess” noise. The acoustic theory of Kerschen and Envia for swept cascades is applied to the problem of axial fan design. These results are compared to available data and a provisional model for specifying sweep angles is presented. The aerodynamic performance theory for swept-bladed rotors of Smith and Yeh is adapted for use in designing low-speed axial fans. Three prototype fans were designed using the resultant computer codes. One is a baseline fan with blade stocking lines radially oriented, and two are fans having swept blades of increasingly greater forward sweep. Aerodynamic testing shows that performance of the fans lies within a band width of about ± 2 percent of volume flow rate and pressure rise predictions in the region of design performance, effectively validating the design procedure for selection of the blading parameters. Noise testing of the fans was carried out and the results show an average noise reduction for the swept-bladed fans of about 7 dBA overall, and a reduction of pure tone noise at blade-pass frequency of about 10 dB compared to the zero-sweep baseline model, in close agreement with the theory of Kerschen and Envia.
41
Liu, Yihui, Yanrong Wang, Dasheng Wei, Xianghua Jiang e Qiannan Tao. "Modeling of Creep Deformation Behavior of DZ411 and Finite Element Simulation of Turbine Blade". Metals 13, n. 8 (2 agosto 2023): 1389. http://dx.doi.org/10.3390/met13081389.
Testo completoAbstract (sommario):
Creep tests were conducted on DZ411 material at 930 °C and 850 °C, and creep curves were recorded and employed in normalization creep model building. A yield function suitable for directional solidification nickel-based materials was proposed in an ascending-order approach. Combined with the normalized creep model and the proposed function, a creep subroutine was compiled to simulate the creep deformation behavior of a turbine blade. The typical boundary conditions of the blade were determined and used for finite element analysis. According to the analysis results, the assessment positions for the actual application of a turbine blade were determined and checked for endurance intensity. The phenomenon of deviation angle between crystal axis and blade height direction in actual casting was further analyzed. Multiple angles and directional deviation angles were simulated for 10,000 h creep deformation. Considering the difficulties and challenges of the complex geometric structures of blades, it is necessary to conduct creep tests of DZ411 material and a simulation analysis of a real blade. Based on the above analysis and discussion, the present work sheds light on finite element analysis and has great potential for structural analyses in the engineering applications of complex high-temperature structures.
42
Ni, Shaosong, Wenbin Cao, Jun Xu, Yingdong Wang e Wei Zhang. "Effects of an Inclined Blade on the Performance of a Sirocco Fan". Applied Sciences 9, n. 15 (2 agosto 2019): 3154. http://dx.doi.org/10.3390/app9153154.
Testo completoAbstract (sommario):
The impeller is the primary working component of centrifugal fans, whose internal flow directly determines the performance of the whole system. This work presents a numerical investigation by using ANSYS-Fluent on the internal flow of a Sirocco fan to investigate the effects of the inclination angle of the blades on the fan performance. The orientation of the blade for the baseline model is strictly along the axial direction, while three inclination angles, i.e., 3.5°, 7.0°, and 10.5°, are chosen for the inclined blades of the modified impeller to improve the aerodynamic performance of the fan. The effects of the inclined blade are demonstrated by the variations in static pressure, efficiency, and pressure and velocity distributions at various inclination angles. The computed results reveal that there is an optimum inclination angle, which produces the best aerodynamic performance.
43
Kyparissis, Spyridon D., e Dionissios P. Margaris. "Experimental Investigation and Passive Flow Control of a Cavitating Centrifugal Pump". International Journal of Rotating Machinery 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/248082.
Testo completoAbstract (sommario):
Passive flow control techniques are used to improve the flow field and efficiency of centrifugal pumps and turbomachines, in general. An important phenomenon that mechanical engineers have to take into account is cavitation. It leads to the decrease of the pump performance and total head. In the present experimental study, a centrifugal pump is investigated in cavitating conditions. A passive flow control is realized using three different blade leading edge angles in order to reduce the cavitation development and enhance the pump performance. The experiments are carried out in a pump test rig specially designed and constructed, along with the impellers. The head drop and total efficiency curves are presented in order to examine the effect of the blade leading edge angle on the cavitation and pump performance. Finally, the vapour distribution along with the blades is illustrated for the tested blade leading edge angles.
44
Mohammed, Abdulbasit, Hirpa G. Lemu e Belete Sirahbizu. "Determining Optimum Rotary Blade Design for Wind-Powered Water-Pumping Systems for Local Selected Sites". Strojniški vestnik – Journal of Mechanical Engineering 67, n. 5 (15 giugno 2021): 214–22. http://dx.doi.org/10.5545/sv-jme.2021.7140.
Testo completoAbstract (sommario):
The design of a windmill rotor is critical for harnessing wind energy. In this work, a study is conducted to optimize the design and performance of a rotor blade that is suitable for low wind conditions. The windmills’ rotor blades are aerodynamically designed based on the SG6043 airfoil and wind speed data at local selected sites. The aerodynamic profile of the rotor blade that can provide a maximum power coefficient, which is the relation between real rotor performance and the available wind energy on a given reference area, was calculated. Different parameters, such as blade shapes, chord distributions, tip speed ratio, geometries set angles, etc., were used to optimize the blade design with the objective of extracting maximum wind power for a water pumping system. Windmill rotor of 10.74 m, 7.34 m, and 6.34 m diameter with three blades were obtained for the selected sites at Abomsa, Metehara, and Ziway in south-east Ethiopia. During the rotary blades performance optimization, blade element momentum (BEM) theory and solving iteration by MATLAB® coding were used.
45
Mohammed, Abdulbasit, Hirpa G. Lemu e Belete Sirahbizu. "Determining Optimum Rotary Blade Design for Wind-Powered Water-Pumping Systems for Local Selected Sites". Strojniški vestnik – Journal of Mechanical Engineering 67, n. 5 (26 maggio 2021): 214–22. http://dx.doi.org/10.5545/sv-jme.2021.7104.
Testo completoAbstract (sommario):
The design of a windmill rotor is critical for harnessing wind energy. In this work, a study is conducted to optimize the design and performance of a rotor blade that is suitable for low wind conditions. The windmills’ rotor blades are aerodynamically designed based on the SG6043 airfoil and wind speed data at local selected sites. The aerodynamic profile of the rotor blade that can provide a maximum power coefficient, which is the relation between real rotor performance and the available wind energy on a given reference area, was calculated. Different parameters, such as blade shapes, chord distributions, tip speed ratio, geometries set angles, etc., were used to optimize the blade design with the objective of extracting maximum wind power for a water pumping system. Windmill rotor of 10.74 m, 7.34 m, and 6.34 m diameter with three blades were obtained for the selected sites at Abomsa, Metehara, and Ziway in south-east Ethiopia. During the rotary blades performance optimization, blade element momentum (BEM) theory and solving iteration by MATLAB® coding were used.
46
Garipova, Lyaysan Ildusovna, Andrei Sergeevich Batrakov, Alexander Nikolaevich Kusyumov, Sergey Anatolievich Mikhaylov e George Barakos. "Aerodynamic and acoustic analysis of helicopter main rotor blade tips in hover". International Journal of Numerical Methods for Heat & Fluid Flow 26, n. 7 (5 settembre 2016): 2101–18. http://dx.doi.org/10.1108/hff-08-2015-0348.
Testo completoAbstract (sommario):
Purpose The design of main rotor blade tips is of interest to helicopter manufactures since the tip details affect the performance and acoustics of the rotor. The paper aims to discuss this issue. Design/methodology/approach In this paper, computation fluid dynamics is used to simulate the flow around hovering helicopter blades with different tip designs. For each type of blade tip a parametric study on the shape is also conducted for comparison calculations were performed the constant rotor thrust condition. The collective pitch and the cone angles of the blades were determined by at an iterative trimming process. Findings Analysis of the distributed blade loads shows that the tip geometry has a significant influence on aerodynamics and aeroacoustics especially for stations where blade loading is high. Originality/value The aeroacoustic characteristics of the rotors were obtained using Ffowcs Williams-Hawkings equations.
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Rhee, Dong-Ho, e Hyung Hee Cho. "Local Heat/Mass Transfer Characteristics on a Rotating Blade With Flat Tip in a Low-Speed Annular Cascade—Part II: Tip and Shroud". Journal of Turbomachinery 128, n. 1 (1 febbraio 2005): 110–19. http://dx.doi.org/10.1115/1.2098767.
Testo completoAbstract (sommario):
The local heat/mass transfer characteristics on the tip and shroud were investigated using a low speed rotating turbine annular cascade. Time-averaged mass transfer coefficients on the tip and shroud were measured using a naphthalene sublimation technique. A low speed wind tunnel with a single stage turbine annular cascade was used. The turbine stage is composed of sixteen guide plates and blades. The chord length of blade is 150 mm and the mean tip clearance is about 2.5% of the blade chord. The tested Reynolds number based on inlet flow velocity and blade chord is 1.5×105 and the rotational speed of the blade is 255.8 rpm at design condition. The results were compared with the results for a stationary blade and the effects of incidence angle of incoming flow were examined for incidence angles ranging from −15 to +7deg. The off-design test conditions are obtained by changing the rotational speed with a fixed incoming flow velocity. Flow reattachment on the tip near the pressure side edge dominates the heat transfer on the tip surface. Consequently, the heat/mass transfer coefficients on the blade tip are about 1.7 times as high as those on the blade surface and the shroud. However, the heat transfer on the tip is about 10% lower than that for the stationary case due to reduced leakage flow with the relative motion. The peak regions due to the flow reattachment are reduced and shifted toward the trailing edge and additional peaks are formed near the leading edge region with decreasing incidence angles. But, quite uniform and high values are observed on the tip with positive incidence angles. The time-averaged heat/mass transfer on the shroud surface has a level similar to that of the stationary cases.
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Molatudi, Errol, Thokozani Justin Kunene e Lagouge Kwanda Tartibu. "A Ffowcs Williams-Hawkings numerical aeroacoustic study of varied and fixed-pitch blades of an H-Rotor vertical axis wind turbine". MATEC Web of Conferences 347 (2021): 00013. http://dx.doi.org/10.1051/matecconf/202134700013.
Testo completoAbstract (sommario):
The effects of sound pressure level at two observation positions of a fixed and varied blade pitch angle at Low-Mach unsteady incompressible Reynolds-Average Navier-Stokes flow approach, on an H-rotor Vertical Axis Wind Turbine. The objective of the study is to compare the noise dissipation and output power/energy of the airfoil blades design of the vertical axis wind turbine in residential zones. The Ffowcs Williams-Hawkings (FHWH) techniques were applied to validate the output noise and vortex shedding of the different angles of attacks (AoA). The study postulated that the time history of the calculated sound pressure level at two observers positions: the aeroacoustic, blade vortex interaction noise, flow separations, dynamic stall experience from varied angled of attacks are found to produces less noise and vortex shedding compared to the fixed angle of attack.
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Li, Yan, Fang Feng, Sheng Mao Li, Wen Qiang Tian e Kotaro Tagawa. "Wind Tunnel Test on Icing on a Straight Blade for Vertical Axis Wind Turbine". Advanced Materials Research 301-303 (luglio 2011): 1735–39. http://dx.doi.org/10.4028/www.scientific.net/amr.301-303.1735.
Testo completoAbstract (sommario):
Icing on blade surface of the wind turbine set in cold regions is a serious problem. To invest the mechanism of icing and ice accretion on blade surface, wind tunnel tests were carried out on a static straight blade used for the straight-bladed vertical axis wind turbine by using an icing wind tunnel. The icing and ice accretions on blade surface at some typical angles of attack were observed and recorded in a fixed wind speed and steady flow discharge. The mass of ice accretions on the surface of blade were also measured and compared. At the same time, the drag and lift coefficients were tested by a three-component force balance. Based on the test results, the factors affecting the mass and characteristic of ice accretions and the drag and lift coefficients of the straight blade were discussed.
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Aiting, Li, Zhu Yangli, Li Wen, Wang Xing, Qin Wei e Chen Haisheng. "An improved inverse method for multirow blades of turbomachinery". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, n. 22 (9 maggio 2020): 4433–43. http://dx.doi.org/10.1177/0954406220924451.
Testo completoAbstract (sommario):
A three-dimensional viscous inverse design method is improved and extended to multirow blades environment. The inverse method takes load distribution as optimization objective and is implemented into the time-marching finite-volume Reynolds-averaged Navier–Stokes solver. The camber line of rotor blade is updated by virtual displacement, which is calculated by characteristic compatibility relations according to the difference between target and actual load so as to control the location and intensity of shock wave, and realize the optimization of flow structure and reduction flow separation. The inlet and outlet geometry angles of stator blade are adjusted in real time according to the inlet and outlet flow angles. Thus, it is computationally ensured that the blade row interactions are accounted and optimization process is carried out under the design condition. To preserve the robustness of calculation, the maximum virtual displacement is limited by Y+ <10 and the camber line is smoothed via cubic B-spline interpolation. The complete blade profile is then generated by adding the prescribed blade thickness distribution to the camber line. The effectiveness of the method is demonstrated in the optimization of Stage35 compressor stage. Numerical results showed that this inverse method can effectively improve the internal flow structure and optimize the matching between blade rows, and this method is robust, efficient, and flexible.