Effect Of Blade Number Research Articles

Effect of number of blades on performance and wake recovery for a vertical axis helical hydrokinetic turbine

Hydrokinetic turbine provides a viable option for tapping energy from free-flowing water, making it an attractive contributor to the renewable power landscape. This study investigates the effects of blade number and solidity on the performance and wake recovery of a small-scale vertical axis helical hydrokinetic turbine under different tip speed ratios and inflow velocities. Computational fluid dynamics simulations are employed, followed by experimental validation, to analyze power, self-start, torque pulsations, velocity deficit and flow field characteristics. The highest power coefficient is found to be 0.24 for a 4-bladed rotor with 0.3 solidity at a tip speed ratio of 1.0 and inflow velocity of 1.0 m/s. The performance of the studied rotors decreases as inflow velocity increases due to high turbulence experienced, resulting in flow separation. The self-start characteristics are shown to improve with solidity, while torque pulsations are greatly diminished with the increase in number of blades. The wake analysis results show that the velocity deficit and turbulence intensity increase significantly as the number of blades increases. Moreover, the time-averaged streamwise velocity values are observed to reach almost 95 % at a downstream distance of 19–25 times the rotor diameter for investigated rotors.

Effect of blade number on rotor efficiency and noise emission at hovering condition

The configuration of rotors significantly impacts the aerodynamic efficiency and noise emission of multicopters. To date, there are no general guidelines regarding how many blades a rotor should use for optimal aerodynamic performance and minimum noise emission. From the perspectives of aerodynamics and acoustics during the hovering condition, two key parameters, i.e., figure of merit (FM) and overall sound pressure level (OASPL), are evaluated to determine the optimal blade number (BN). The number of blades chosen in this study is BN = 2–6, which is largely observed in commercial multicopters. A genetic algorithm was developed to optimize blade design for each BN-rotor configuration. The individuals are evaluated by steady computational fluid dynamics (CFD) simulations and acoustic analogy for optimizations, and the detailed analyses of optimal ones are further explored by unsteady CFD simulations. The planform of the baseline blade is maintained, and the radial distribution of twist angles is the parameter for optimization. While generating the same thrust, the value of FM keeps increasing as the number of blades increases from 2 to 4, after which the FM value reaches a plateau. The value of OASPL keeps decreasing as the number of blades increases. The reason for the FM and OASPL value trends vs blade number is explained with the numerical simulation results, and a general design rule is suggested at the end.

Effect of Blade number on the Energy Dissipation and Centrifugal Pump Performance Based on the Entropy Generation Theory and Fluid–Structure Interaction

Effect of Blade number on the Energy Dissipation and Centrifugal Pump Performance Based on the Entropy Generation Theory and Fluid–Structure Interaction

Dynamics of nonlinear beam-propeller system with different numbers of blades

The dynamics of elastic systems coupled with rotating bladed-rotors is rich and complex, and the blade number may have an influence on the in-vacuo system dynamics. This paper aims to model its nonlinear dynamics in-vacuo and study the effects of blade number on its dynamics. To this end, a nonlinear model consisting of a nonlinear inextensible beam, a motor assembly and a rotating propeller is developed. This model is linearized, and modal analyses are performed with different blade numbers. It is validated numerically and experimentally that a two-bladed propeller introduces time-varying characteristics, while the system is time-invariant with more than two blades. For the two-bladed case, frequencies in the non-rotating condition split into two frequency loci with increasing rotational speed; while with more than two blades, one frequency in the non-rotating condition increases and the other in the same pair decreases with increasing speed. A structural instability due to frequency lock-in is identified in two-bladed configuration, while not identified with more than two blades. The static deformation using the nonlinear model is calculated and validated against the experiment. In the stable speed range, the frequency response functions calculated using the nonlinear and linearized models do not show notable differences. In the unstable speed range with two-bladed propeller, the nonlinear model is consistent with the experiment in terms of unstable frequencies and bounded steady-state oscillations. The system vibration in the unstable speed range features forward whirling pattern, in which the beam vibration is close to the first bending pattern.

Influence of the number of front and rear rotor blades on the hydrodynamic performance of counter-rotating horizontal-axis tidal turbines

The coaxial rotor structure presents significant potential for the development of tidal turbines. In order to study the effect of the number of front and rear rotor blades on the hydrodynamic performance of counter-rotating horizontal-axis tidal turbines (CRHATTs), three models (CRHATT 3-2, CRHATT 3-3 and CRHATT 3–4) are established at the same tip speed ratio (TSR), and the accuracy of the numerical method is verified by experiments. The effect of blade number on the performance coefficients, velocity and pressure pulsations and vortex structure of CRHATTs are calculated based on CFD method and spectral analysis. The results show that the relationship of the power coefficient for the three models is: CRHATT 3–4 > CRHATT 3-3 > CRHATT 3-2. The turbulent kinetic energy in the flow field can be transferred more quickly from the large-scale vortex structure to the small-scale as the number of rear rotor blades increases. By weighing aspects such as load fluctuation and power coefficient, the CRHATT 3–4 can produce the largest power coefficients, the best stability during operation and the least vibration on the blades among the three models. This paper provides significant guidance for the engineering design and optimization research of CRHATTs.

Forecasting Effect of Blade Numbers to Cross-Flow Hydro-Type Turbine with Runner Angle 30° Using CFD and FDA Approach

Forecasting Effect of Blade Numbers to Cross-Flow Hydro-Type Turbine with Runner Angle 30° Using CFD and FDA Approach

Numerical analysis of the effect of the blade number on the hydrodynamic performance of shaftless rim-driven thruster

In this work, numerical investigations were performed to the study the effect of blade number on the hydrodynamic performance of shaftless Rim-driven Thruster (RDT) with certain blade area ratio and pitch ratio. The work investigated and compared the thrust coefficient, torque coefficient and efficiency of the RDTs with different blade numbers. Additionally, this work detected and analyzed the pressure distribution on the blade surface and velocity distribution around the blade and in the wake. The results demonstrate that for a certain advance coefficient, the thrust coefficient and torque coefficient of the RDT increase with the blade number, however the efficiency of the RDT decreases with the increase of blade number. For the same cross-section and advance coefficient, the 7-blade RDT has higher thrust and torque than the 3-blade RDT due to the large friction and pressure difference between the suction and pressure surfaces. The high velocity of both RDTs appears at the junction between each blade and the duct, and the 7-blade RDT has higher velocity in the wake and in the cross-section than the 3-blade RDT. The 3-blade RDT has the high pressure at the leading edge on the suction surface of each blade. However, the 7-blade RDT has not only the high pressure at the leading edge, but also the high negative pressure at the blade root on the suction surface of each blade, so 7-blade RDT has higher torque that 3-blade RDT.

Effect of Blade Number on the Performance of a Centrifugal Pump Using Commercial Tool ANYS 91.2

Computational fluid dynamics (CFD) is frequently used in centrifugal pump design. The characteristics of the flow fields around turbomachinery can be simulated using tools for numerical computational fluid dynamics in three dimensions. Numerical simulation, which also provides significant information for the hydraulic design of the centrifugal pump, can be used to visualize the internal flow condition of a centrifugal pump. The purpose of this study was to examine the effect of blade number on the hydraulic performance curve using a commercial instrument. ANSYS 91.2. code commercial.The geometric model of the pump was built using CF turbo, and the flow domain was meshed using the commercial programme ICEM. The results demonstrated that an increase in the number of blades significantly improved the hydraulic performance of the centrifugal pump’s head. The findings also revealed that the area of the low-pressure zone at the blade’s input suction grew and that the static pressure distribution homogeneity in the diffusion section was significantly better than that in the spiral section. The design flow of 35 m3 per hour is where the best efficiency point (BEP) is located. At Z = 6 and Z = 7, the head values were 51.58 m and 53.13 m, respectively, while the efficiency values were 50.32% and 53.35%. The comparison of the H-Q curve for estimated head discharge indicates that all impeller efficiency curves share the same fundamental tendency.

Experimental and Numerical Investigation of the Effect of Blades Number on the Dynamic Response of a Small Horizontal-Axis Wind Turbine

The new energy scenario is rising a strong interest towards the distributed production from renewable sources; among them, wind seems to be one of the most interesting and at the same time critical due to the challenges of the conversion technology. Operation of small wind energy conversion systems is generally very complex due the extremely variable regime of operation and the high turbulent wind, so that a deep knowledge of the dynamic response of such devices is crucial not only for optimising their performances but also to make them comfortable to be used in residential areas. For these reasons, the present work is focused on analysing the effect in changing the number of blades on a small horizontal axis wind turbine through an experimental campaign in the wind tunnel. The turbine dynamics has been characterised running some “wind ramp” tests and analysing the rotor capability in following the wind as well the vibrations transmitted by the turbine during the operation. Results demonstrate that a higher number of blades, despite a small decrease of performance, can make the machine more efficient in operating at low wind regimes. At the same time, a higher number of blades can make the rotor efficient even at lower speed of rotation, thus limiting the risks of having high magnitude vibrations.

Effects of blade number on the aerodynamic performance and wake characteristics of a small horizontal-axis wind turbine

Small-scale horizontal-axis wind turbines (SHAWTs) are powerful equipments for wind energy conversion. Furthermore, the wake vortices generated by SHAWTs are used in structural engineering to potentially mitigate vibrations. The blade number of SHAWTs is an important parameter for determining the wake vortices, and thus, in addition to its impact on power generation, it significantly influences structural vibration control. Consequently, the aerodynamic performance and wake characteristics of SHAWTs, with blade numbers from 2 to 5 and tip speed ratio from 1 to 6, were systematically investigated using large-eddy simulations and wind tunnel tests. A superior SHAWT with a high power coefficient (>35 %) was designed. The near-wake characteristics and wake evolution were highly sensitive to blade number. An increased number of rotor blades resulted in a (i) wider near wake, (ii) faster decrease in streamwise vorticity, and (iii) greater velocity deficit (VD) and turbulence intensity (TI) in the near wake. Furthermore, in the far wake, the unstable positions of the tip vortices and peak positions of the TI were closer to the rotor and the VD recovered faster, causing the wind-speed distribution to transition from W-shaped to V-shaped. The results have significant implications for the design optimisation of wind energy harvesting. Moreover, they are potentially beneficial for the control of structural vibration using SHAWTs.

Effect of blade number on the performance of centrifugal fan

The present-day energy crisis challenges the engineers to take careful steps in design of fans. Enhancing the performance of centrifugal fan through parametric analysis is one of the ways. Simulation of centrifugal fan is demonstrated by considering a preliminary design model of backward curved bladed impeller centrifugal having 11 blades (MD1) which is designed using theoretical concepts from fan handbooks to achieve an air capacity of 7 m3/s producing a total pressure at outlet of fan to be 2000 Pa while impeller running at 1500 RPM which is the industrial requirement. Solid model is created and simulation is performed to analyze the fluid flow using Computational Fluid Dynamics (CFD). Results of this preliminary model show that a total pressure of 1323.07 Pa at the outlet of fan is achieved with an efficiency of 50.82%. Need for improvement in performance and to the study of effect of blade number on the model has led to perform simulations by varying the number of blades of impeller to Z = 8, 10, 12, 14 while keeping all the parameters identical to the design point condition. Contour plots of flow and velocity vectors in the blade passages areas for different cases along with the total pressure and efficiency are compared. Assessment of these results shows that when blade number Z = 14, there is an increase in total pressure by 21.77% and efficiency by 5.74% in comparison with design point condition. The centrifugal fan is simulated successfully as the residuals shows good convergence of <10−5.

A numerical investigation of the effect of blade number on the performance of an INSEAN E779A marine propeller in a cavitating flow using computational fluid dynamics

A propeller's thrust coefficient, efficiency, and torque coefficient are important performance characteristics. They can be harmed by the presence of cavitating flow. Previous numerical studies have shown that cavitating flow can damage a marine propeller as well as reduce its performance. The work presented here investigates the effect of blade number variation on the performance of an INSEAN E779A marine propeller in a cavitating flow. The cavitating flow simulations are performed using computational fluid dynamics with four different rotational and inlet speeds using the fully turbulent standard k-ε model and the Schnerr-Sauer cavitation model. The numerical results of varying the number of blades on propeller performance characteristics are presented here. It is concluded that increasing the number of propeller blades improves propeller performance. In contrast, the cavitation area is reduced, but cavitation is more likely to occur as rotational speed increases.

Sand-ejecting fire extinguisher parameter sensitivity analysis based on DOE and CFD-DEM coupling simulations

To get more accurate quantitative impact effects of selective parameters of the sand-ejecting fire extinguisher on the scattering results by the CFD-DEM coupling method, orthogonal experimental design, analysis of range and variance, full factorial design and the OFAT design were used in this paper. The single impact effects and mixed impact effects of blade number, blade incidence and sand mass flow on scattering vertical distance and inclination were analysed and concluded, as well as the details of the sand distribution. The results show that only the sand mass flow has the dominating influence on the vertical distance, while all three factors have no significant influence on the scattering inclination. The larger the sand mass flow is, the more obvious influence of air resistance and airflow from the outlet of the scattering unit can be shown, and the scattering bifurcation phenomenon can be displayed more obviously.

Investigation of the influence of blade configuration on the hemodynamic performance and blood damage of the centrifugal blood pump.

The design and optimization of centrifugal blood pumps are crucial for improved extracorporeal membrane oxygenation system performance. Secondary flow passages are common in centrifugal blood pumps, allowing for a high volume of unstable flow. Traditional design theory offers minimal guidance on the design and optimization of centrifugal blood pumps, so it's critical to understand how design parameter variables affect hydraulic performance and hemocompatibility. Computational fluid dynamics (CFD) was employed to investigate the effects of blade number, blade wrap angle, blade thickness, and splitters on pressure head, hemolysis, and platelet activation state. Eulerian and Lagrangian features were used to analyze the flow fields and hemocompatibility metrics such as scalar shear stress, velocity distribution, and their correlation. The equalization of frictional and flow losses allow impellers with more blades and smaller wrap angles to have higher pressure heads, whereas the trade-off between the volume of high scalar shear stress and exposure time allows impellers with fewer blades and larger blade wrap angles to have a lower HI; there are configurations that increase the possibility of platelet activation for both number of blades and wrap angles. The hydraulic performance and hemocompatibility of centrifugal blood pumps are not affected by blade thickness. Compared to the main blades, splitters can improve the blood compatibility of a centrifugal blood pump with a small reduction in pressure head, but there is a trade-off between the length and location of the splitter that suppresses flow losses while reducing the velocity gradient. According to correlation analysis, pressure head, HI, and the volume of high shear stress were all substantially connected, and exposure time had a significant impact on HI. The platelet activation state was influenced by the average scalar shear stress and the volume of low velocity. The findings reveal the impact of design variables on the performance of centrifugal blood pumps with secondary flow passages, as well as the relationship between hemocompatibility, hydraulic performance, and flow characteristics, and are useful for the design and optimization of this type of blood pump, as well as the prediction of clinical complications.

Effects of Blade Number on the Centrifugal Pump Performance: A Review

Effects of Blade Number on the Centrifugal Pump Performance: A Review

Effects of Blade Number on the Propulsion and Vortical Structures of Pre-Swirl Stator Pump-Jet Propulsors

Reducing the noise of the underwater propulsor is gaining more and more attention in the marine industry. The pump-jet propulsor (PJP) is an extraordinary innovation in marine propulsion applications. This paper inspects the effects of blade number on a pre-swirl stator pump-jet propulsor (PJP) quantitatively and qualitatively. The numerical calculations are conducted by IDDES and ELES, where the ELES is only adopted to capture the vortical structures after refining the mesh. The numerical results show good agreement with the experiment. Detailed discussions of the propulsion, the features of thrust fluctuation in time and frequency domains, and the flow field are involved. Based on the ELES results, the vortices in the PJP flow field and the interactions between the vortices of the stator, rotor, and duct are presented. Results suggest that, though changing the blade number under a constant solidity does not affect the propulsion, it has considerable effects on the thrust fluctuation of PJP. The wakes of the stator and rotor are also notably changed. Increasing the stator blade numbers has significantly weakened the high-intensity vortices in the stator wake and, hence, the interaction with the rotor wake vortices. The hub vortices highly depend upon the wake vortices of the rotor. The hub vortices are considerably broken by upstream wake vortices when the load per rotor blade is high. In summary, the blade number is also vital for the further PJP design, particularly when the main concerns are exciting force and noise performance.

Influence of blade numbers on start-up performance of vertical axis tidal current turbines

To alleviate the energy crisis, the tidal energy extraction has become a hot topic in recent years. As a commonly utilized energy converter, a primary concern of vertical axis tidal turbines (VATTs) is the incapability to self-start. Previous studies have found that the starting performance has a great correlation with the number of blades. However, the detailed effects of blade number on starting characteristic are not fully understood. Therefore, it is necessary to further assess the influences of the number and azimuthal angle of blades on starting characteristics. In this study, we investigate the effects of the blade number on start-up performance of VATTs by means of the commercial Computational Fluid Dynamic (CFD) software CFX. It can be seen that the increase of the blade number results in a more homogeneous flow field, and the varying angles can lead to a high average torque. Besides, the region of 100°–120° is proved that all turbines with three different blade numbers can achieve a better starting performance.

Effects of blade number and draft tube in gravitational water vortex power plant determined using computational fluid dynamics simulations

Effects of blade number and draft tube in gravitational water vortex power plant determined using computational fluid dynamics simulations

Evaluation of the Effect of Blades Number on the Performance of Pico Wind Turbines

In this paper, the influence of blades number on the performance of pico wind turbine was investigated by using a small-motorized axial DC fan with a rated power of 4W. Fixed streaming air blower was used as a source of wind. Varying in wind speed was accomplished by changing the distance from the blower. A resistor equals to the turbine internal resistance was utilized as a load to collect the electrical power across the load at various wind speeds and for fans of different blades (1, 2, and 5). Values of the cut-in and cut-out speeds were extracted from the power plot. Rated power was recorded, as well. The results have shown that the rated power generated by turbine has decreased due to the reduction of blades number (i.e., reduction in solidity) from 2.6W for a 5-bladed turbine to 0.665W for a 2-bladed turbine and to 0.13W for a 1-bladed turbine. Moreover, the cut-in speed (initial electrical generating speed) has increased from 4.9m/s for 5-bladed to 8m/s for 2-bladed, then to 19.15m/s for 1-bladed. These results are explained by the balancing problems during rotation (polar asymmetrical rotor), and it is seen that the reduction of blades has made a sharp reduction in power coefficient.

Experimental and numerical investigation of the effect of blade number on the aerodynamic performance of a small-scale horizontal axis wind turbine

This study presents experimental and numerical investigation for the effect of number of blade (solidity) on the power and thrust coefficients of a small-scale horizontal-axis wind turbine HAWT. An experimental set- up was installed on wind turbine rotors with different number of blades, i.e. three, five and six, and at different tip speed ratios, in the closed-circuit open-test section wind tunnel. The obtained results from CFD simulations were performed to compare numerical data with experimental measurements. In addition, there is a lack of information presented for the effect of rotor blade number on the flow field for HAWT like vertical axis wind turbine VAWT. Therefore, the current study extends to study the effect of solidity on the flow field using numerical calculation. The numerical simulation was performed using a steady-RANS method. The SST k-ω turbulence model was used to represent turbulence characteristics. It is found that decreasing the number of blades (which makes the turbine less sensitive to the change in tip speed ratio) the wind turbine with 3 blade configuration has the maximum power coefficient in respect to 5 and 6 blade turbines, higher by around 2 and 4 percent respectively.