Increase In Number Of Blades Research Articles

Blade number effects on performance and internal flow dynamics in high-speed coolant pumps

The high-speed coolant pump is a critical component in battery energy storage systems, responsible for circulating heat transfer fluid and enabling efficient thermal energy exchange. This study investigates the effect of blade number (Z = 4–9) on the pump's energy performance and internal flow characteristics through experimental and numerical methods. Results show that as the blade number increases, the head and efficiency initially rise and then decline, with Z = 6, Z = 7, and Z = 8 achieving comparable performance at 1.0Qd. While changes in blade number minimally affect disk, volumetric, and volute efficiencies, they significantly influence hydraulic and impeller efficiencies. Pressure distribution analysis reveals that increasing the blade number to Z = 6 and Z = 7 reduces the low-pressure region at the impeller inlet and improves uniformity. Flow characteristics analysis shows that increasing the blade number reduces flow separation and the “jet-wake” effect but an excessive number of blades also raises turbulent kinetic energy, compromising flow stability. Similarly, entropy production decreases initially but rises again at Z = 8 and Z = 9, resulting in reduced energy performance. Overall, the pump's energy performance and internal flow characteristics follow an “inverted U-shaped” trend as blade number increases, highlighting the importance of selecting an appropriate blade number to improve flow conditions, minimize energy losses, and enhance operational stability. This study provides valuable insights for optimizing blade design in coolant pumps.

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

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

The Influence of Blade Structure Optimization on the Hydraulic Performance of Vane Pump

Vane pump has the problems of low pressure reduction efficiency and easy to be stuck at the bottom of the well. In order to solve this problem, the annular pressure reduction downhole tool of vane pump based on eddy current principle is adopted. On the basis of introducing the principle of eddy current hydraulic pressure reduction technology, this paper studies the influence of blade number, blade outlet angle, blade chord height and blade thickness on tool characteristics. The results show that the tool head increases with the increase of blade number, increases first and then decreases with the increase of blade outlet angle, and decreases first and then stabilizes with the increase of blade wall thickness and chord height. The tool efficiency increases with the increase of blade number, decreases with the increase of blade chord height, and decreases with the increase of blade outlet angle to a certain value, which is less sensitive to blade wall thickness. The research results have important guiding significance for the design and structural optimization of blade annular pressure reducing tools.

Numerical study on the hydrodynamic performance and wake dynamics of propulsive wing propulsors with different cross-flow fans

The propulsive wing propulsor (PWP), which means an underwater thruster equipped with a wing, a cross-flow fan (CFF), and a deflector, is capable of generating both horizontal thrust and vertical lift, thus enhancing the maneuverability of underwater vehicles and serving as a propulsion device. The hydrodynamic performance of the PWP is significantly influenced by the blade number it possesses. An unsteady numerical method based on the Reynolds-averaged Navier–Stokes equations was developed to examine the impact mechanism of blade number on the hydrodynamic performance, load fluctuation, and wake evolution of the PWP. The results indicate that as the blade number increases, the hydrodynamic forces, power, and propulsive efficiency of the PWP gradually increase. When the blade number exceeds 26, the performance of the PWP tends to stabilize. Insufficient blades can lead to turbulence in the internal flow of the CFF, intensifying interference between blade vortices, resulting in secondary peaks and frequency-domain bifurcations in hydrodynamics. With an increasing blade number, disturbances to the blade vortices decrease, enhancing the periodicity of PWP hydrodynamic fluctuations, but there may be an increase in high-frequency noise levels. The wake modes of the PWP undergo four transitions: double vortex pair mode, single vortex pair mode, single vortex pair + single vortex mode, and vortex strip mode. Disturbed blade vortices promote the transition of vortex pair shedding modes in the PWP wake, thereby causing variations in the periodicity of PWP hydrodynamics. Excessive amplitude and frequency may lead to structural fatigue damage in the PWP.

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.

Experimental and Numerical Investigation on the Transient Cavitating Flows in a Mixed Flow Pump With Different Number of Blades at Startup

Abstract The objective of this paper is to experimentally and numerically investigate the transient cavitation flow during the startup process of mixed flow pump with emphasis on studying the influence of blade numbers. The transient cavitation simulation was studied based on the improved SST k–ω turbulence model and the Zwart cavitation model. Firstly, in order to obtain the relationship between transient flow rate and the variation of rotational speed at startup, a theoretical analysis based on the fast transients of centrifugal pump was first applied to mixed flow pump and was verified by the current experiment study. Subsequently, the influence of blade number on the cavitation flow in the startup was studied. It is found that the transient cavitation could be classified into four stages regardless of the number of blades: no cavitation stage, the cavitation growth stage, the cavitation reduction stage and the cavitation stabilization stage. However, the blade number does have an impact on the spatial-temporal evolution of cavitation. More specifically, when the blade number increases, the initial cavitation appeared lately, the coverage area of the triangular cavitation cloud and sheet cavitation both decreased, and the increase in blade number has a better inhibitory effect on the sheet cavitation at the cavitation growth stage, and can make sheet cavitation disappear more quickly at the cavitation reduction stage.

Numerical investigation of granular mixing in an intensive mixer: Effect of process and structural parameters on mixing performance and power consumption

• Mixing experiments were developed for verifying DEM model. • The mixing performance increases with the decrease of impeller offset. • The impeller with 3 blades has the highest energy efficiency. • The mixing efficiency and energy efficiency increase with the decrease of filling level. Discrete element method (DEM) simulations of particle mixing process in an intensive mixer were conducted to study the influence of structural and process parameters on the mixing performance and power consumption. The DEM model was verified by comparing the impeller torque obtained from simulation with that from experiment. Impeller and vessel torque, coordination number ( CN ) and mixing index (Relative standard deviation) were adopted to qualify the particle dynamics and mixing performance with different parameters. A method based on cubic polynomial fitting was proposed to determine the critical mixing time and critical specific input work during the mixing process. It is found that the mixing performance and energy efficiency increases with the decrease of impeller offset. The mixing performance is improved slightly with the increase of blade number and the impeller with 3 blades has the highest energy efficiency due to its low input torque. Results indicate that the energy efficiency and the mixing performance increase with the decrease of filling level when the height of granular bed is higher than that of blade.

Determination of Rotor Power Consumption in a Thin Film Scraped Surface Heat Exchanger

Scraped surface heat exchangers (SSHE) are prevalent in the food industry to heat/cool viscous fluids and to provide enhanced mixing. The present study was undertaken to determine the power consumption for different blade assembly configurations for the first stage and second stage SSHE. Milk was concentrated from 15% to 26% total solids using first stage SSHE and 32 to 52% total solids using second stage SSHE. Effect of number of blades (2,4,6) weight of blades (1.6, 1.75, 2.0 kg) and (1.75, 2.0 kg, 2.25 kg ) and rotor speed (150, 175, 200 rpm) and (125,150, 175 rpm) was investigated on power consumption (W) using Response Surface Methodology for the first stage and second stage SSHE. The results show that power consumption increased linearly with increase in number of blades as well as rotor speed. Power consumption varied from 420 to 734 W for the first stage SSHE and it varied from 448 to 755 W for the second stage SSHE for all weight of the blades.

An experimental investigation into performance characteristics of H-shaped and Savonius-type VAWT rotors

Abstract The effects of flow regime and rotor configuration strongly influence the power performance of vertical axis wind turbines (VAWTs). Yet, there exits few experimental investigations from literature that have been carried to explain this effect. This could be attributable to huge wind tunneling cost requirement and an array of design skills required including time constrains. The balance between cost and power performance has limited development of VAWTs towards utility scale type. In this paper therefore, we seek to investigate in detail the performance characteristics of vertical axis wind rotors in a wind tunnel environment. The H-Darrieus and Savonius-type VAWT configurations have been utilized to carry out the investigation. A systematic analysis of effect of blade number, rotor configuration, and flow regime including comparison of the two configurations was presented to predict the power performance using a rotary sensor. Results revealed a significant impact of flow field regime on power performance of the VAWT models, with the Savonius-type rotor attaining lower power coefficient ( C P ) than the Darrieus-type rotor across all the tested wind speeds. In addition, increase in number of blades for Darrieus-type rotor revealed narrower negative C P band that decreased with increase in wind speeds. In both configurations, the C P decreased at low tip speed ratios while an increase in C P was revealed at high tip speed ratios. The understanding gained from the results could be useful to the VAWT research community, and the findings can be extended to the design of wind turbines for mini-grid and utility scale applications.

COMPUTATIONAL PREDICTION OF A PROPELLER PERFORMANCE IN OPEN WATER CONDITION

In presence of hydrodynamics phenomena occur surrounding propeller evidently affects on accuracy’s prediction of thrust, torque and its efficiency. To achieve the objective, a Computational Fluid Dynamics (CFD) simulations approach is then proposed to obtain a reliable prediction of the thrust (KT), torque (KQ) and efficiency (η) coefficients in open water condition. The effect of various blade numbers associated with constant propeller revolution (RPM=1320) and pitch ratio (P/D=1.0); are performed within the range of advance ratio from 0.1J1.0. The results revealed that the increase of blade number from Z=3 to 5 was proportional with the increase of thrust (KT) and torque (KQ) coefficients; meanwhile, it was reduced the maximum efficiency (η) that possibly lead to downgrade the propeller performance. It should be noted here, the propeller with three blade numbers (Z=3) provide the highest efficiency (η) up to 78.8% at J=0.9. These CFD simulation results are very useful as a preliminary study of propeller characteristics.

A computational investigation of noise spectrum due to cavitating and non-cavitating propellers

In this article, noise spectrum of marine propellers is investigated in uniform flow under non-cavitating and cavitating conditions. New results are presented for this research field. Hydrodynamic performance of both non-cavitating and cavitating marine propellers is first analyzed by viscous and potential based flow solvers. In viscous solver, sheet cavitation on propeller blades is simulated with Schnerr–Sauer cavitation model based on Rayleigh Plesset equation using volume of fluid approach. Numerical hydrodynamic results based on viscous solver is compared with potential solver and then validated with experimental data of benchmark David Taylor Model Basin 4119 model propeller. Later, noise spectrum of model propellers is predicted by a hybrid method which combines Reynolds-averaged Navier Stokes and Ffowcs Williams Hawkings equations. Computed noise spectrum is compared with other numerical studies in the literature for the selected model propeller. In addition, hydrodynamic and hydroacoustic pressures are compared in near field to show reliability of numerical solution. Effects of blade number on hydrodynamic performance and noise spectrum are also investigated. Numerical results indicated that as blade number increases, propeller noise level decreases for different loading conditions due to decreased blade loading (circulation) per blade. However, propeller efficiency increases as blade number decreases.

Numerical analysis on effects of blade number on hydrodynamic performance of low-pitch marine cycloidal propeller

Marine cycloidal propeller, as a special type of marine propulsion system, is used for ships that require high maneuverability, such as tugs and ferries. In a marine cycloidal propeller, the thrust force is generated by rotation of a circular disk with a number of lifting blades fitted on the periphery of the disk, so that the propeller axis of rotation is perpendicular to the direction of thrust force. Each blade pitches about its own axis, and the thrust magnitude and direction can be adjusted by controlling the pitching angle of the blades. Therefore, the propulsion and maneuvering units are combined together and no separate rudder is needed to maneuver the ship. Two configurations of marine cycloidal propeller have been studied and developed based on propeller pitch: low-pitch propeller (designed for advance coefficient less than one, means λ < 1) and high-pitch propeller (designed for λ > 1). Low-pitch marine cycloidal propellers are used in applications with low-speed maneuvering requirements, such as tugboats and minesweepers. In this study, the effects of blade number on hydrodynamic performance of low-pitch marine cycloidal propeller with pure cycloidal motion of the blades are investigated. The turbulent flow around marine cycloidal propeller is solved using a 2.5D numerical method based on unsteady Reynolds-averaged Navier–Stokes equations with shear-stress transport k–ω turbulent model. The presented numerical method was validated against experimental data and showed good agreement. The results showed that the thrust coefficient of marine cycloidal propeller generally decreases by increasing the blade number, whereas the torque coefficient increases. Consequently, the hydrodynamic efficiency of marine cycloidal propeller drops as the blade number increases.

Numerical study of effect of solidity on vertical axis wind turbine with Gurney flap

Abstract In order to increase the efficiency of straight-bladed vertical axis wind turbine (SB-VAWT), the inboard, outboard, two-side Gurney flap (GF) and dimple-GF are applied in SB-VAWT. The two-dimensional CFD simulation is utilized in this paper. Based on the validation of numerical simulation, the power coefficient, torque coefficient, vorticity field and standard deviation of fluctuation aerodynamic load of SB-VAWT are obtained. The results indicate that all kinds of GF can enhance the power coefficient in a certain range of tip-speed ratio (TSR). Compared to the clean SB-VAWT with solidity of 0.25, the outboard dimple-GF can increase the maximum power coefficient by 17.92% at TSR = 3.1. At all TSR, the two-side dimple-GF can obviously shrink the scale of trailing vortex and decrease the vorticity magnitude of trailing vortex. The outboard GF and dimple-GF can significantly increase the power coefficient of SB-VAWT with the different solidities at low TSR. When the blade number increases, the load fluctuation is reduced and the aerodynamic performance is decreased due to the intense interaction among the trailing edge vortices of multiple blades. A lowest load fluctuation is achieved at the blade number of 5.

Hydrodynamic Design of Tidal Current Turbine and the Effect of Solidity on Performance

Blade element momentum (BEM) flow model in conjunction with pattern search optimization algorithm embedded in the National Renewable Energy Laboratory (NREL) tool HARP_Opt was used to design a horizontal axis tidal current turbine (HATCT). The numerical method was validated with the experimental data and a good agreement was achieved. The designed turbine has a 3 bladed rotor of 4 meters diameter and rated mechanical power of 20 kW. Performance metrics of the rotor for steady and uniform flow was simulated at flow speeds from 0.5-3.5 m/s. The turbine achieved its rated power at a tip speed ratio (TSR) 5.7 with a peak CP value of 0.47 and peak thrust of 16.7 kN-m. Additionally, a series of simulations were performed at TSR from 1-10 to obtain performance curve for the turbine at a design current velocity of 1.5 m/s. Effect of solidity on performance was quantified by varying the number of turbine blades. The value of CP increased by 1.5% with increasing the number of blades from 2 to 3. The value of CP further increased by only 0.2% with increase in number of blades from 3 to 4. The value of turbine thrust was minimally effected by increase in the number of blades. However, the value of thrust per blade increased with a reduction in number of blades. The increase in flap moment and thrust per blade with reduction in number of blades could have serious consequences for the structural integrity of the turbine.

Design Aspect of Scraper Blade Assembly for Enhancing Film Heat Transfer Coefficient of Scraped Surface Heat Exchanger

AbstractScraped surface heat exchangers (SSHEs) are known for thermal processing of viscous food products. Heat transfer coefficient is one of the main parameter which influences the performance of processing liquid products in SSHE. The present study was undertaken to determine the film heat transfer coefficient for different blade assembly configurations. Milk was concentrated from 15 to 26% total solids using SSHE. Effect of number of blades (2, 4, 6), weight of blades (1.6, 1.75, 2.0 kg) and rotor speed (150, 175, 200 rpm) was investigated on scraped film heat transfer coefficient (hs) using Response Surface Methodology. The results showed that hs increased linearly with increase in number of blades as well as rotor speed and that it was inversely related to blade weight. The hs varied from 695.3 to 1,415.4 W/m2K. The study was helpful in determining the design factors affecting film heat transfer coefficient of SSHE.Practical ApplicationsIn many of the earlier studies on SSHE, effect of scraper speed, flow rate or the number of blades has been individually studied. Therefore, effort was made to study the combined effect of these parameters. This article gives important insights on the design aspect of rotor blade assembly for thin film SSHE.

Design & Fabrication of PVC Bladed Inexpensive Wind Turbine

The objective of this paper is to demonstrate that PVC blade profile has better power capacity. Creates scope for designing & Performance evaluation of a specially designed micro wind turbine for area especially in plateau region where velocity of wind is low, invariable average and dry, so where large wind turbine doesn't give satisfactory result. The small wind turbine and their wide scope of application need the comprehensive attempt to be taken place. The small wind turbine i.e. multi blade turbine with increase in number of blades can be run successfully with proper adjustment of swept area and angle of attack. The advantage of the micro wind turbine is that, apart from its low cost, it can be propelled by a wind speed as low as 2 m/s.It is the renewable source of energy which is the clean source. It can be installed over the houses for power generation in our local areas because of low cost and being of economical. Using of small wind turbines for house hold would result in fewer burdens on grid and also plays a vital role in reducing utilization of conventional energy and mobility to utilize the power.

The Influence of the Number of Impeller’s Blade on the Performance of Multistage Centrifugal Pump

Abstract: In order to understand the relationship between the number of blade and the performance of the self-balance multistage centrifugal pump’s first stage impeller internal flow characteristics, Reynolds Navier-Stokes equation and κ~ε turbulence model are used for numerical simulation. The objects of numerical simulation are five self-balance multistage centrifugal pump’s first stage impellers, the blade number of them is 4，5，6，7，8.Under the rated flow ,the numerical simulation obtain five kind of impeller inner flow field distribution , Through the comparative analysis ,when the number of blade is 4,8,the flow of the impeller’s inner and pressure distribution become chaos ;And, the number of blade is 5,6,7, With the increase of blade number, the impeller internal flow are smoother，the head and efficiency are enhanced correspondingly.

Influence of Blade Number on the Performance and Pressure Pulsations in a Pump Used as a Turbine

The rotor-stator interaction of a rotating impeller and a stationary volute could cause strong pressure pulsations and generate flow induced noise and vibration in a pump used as a turbine (PAT). Blade number is one of the main geometric parameters of the impeller. In this paper, a numerical investigation of the PAT’s unsteady pressure field with different blade numbers was performed. The accuracy of global performance prediction by computational fluid dynamics (CFD) was first verified through comparison between numerical and experimental results. Unsteady pressure fields of the PAT with different blade numbers were simulated, and the pulsations were extracted at various locations covering the PAT’s three main hydraulic parts. A detailed analysis of the unsteady pressure field distributions within the PAT’s control volume and comparison of unsteady pressure difference caused by the increase of blade number were performed. The transient flow results provided the unsteady pressure distribution within PAT and showed that increasing the blade number could effectively reduce the amplitude of pressure pulsations. Finally, unsteady pressure field tests were performed and some unsteady results obtained by unsteady field analysis were validated.

On Blade Arrangement for Multi-Blade Rotors

This paper concerns the blades of multi-bladed water-pumping windmills when they have variable mass and centre of mass. The paper explores blade arrangement strategies that will minimize the eccentricity of the rotor centre of mass and hence any rotor-induced vibration. The number of blades in the rotor is assumed to equal the number made in each production batch, in contrast to the case where a batch of up to 22 blades was optimally matched to produce two- and three-bladed rotors, Hitz & Wood [1]. Using the measured mass and centre of mass of 24 blades for the rotor of a 26 ft Kijito windmill described by Harries [3], three strategies are considered. Random matching of the blades is shown to become increasingly effective as blade number increases. Pairing the blades by ordering in the product of mass and centre of mass, d, followed by random selection of pairs also produces rotors with low eccentricities. The numerical experiments show that the best strategy involving random selection is to pair by ordering, swapping the blades of every second pair, and then randomly arrange the resulting pairs. Finally, a heuristic based on blade pairing is shown to give eccentricities which are high compared to the minimum value determined exactly for 12 blades or less, but apparently low enough to be useful.

Computer-Aided Development of Rotary Blades for Strip-Tillage

Rotary blades in strip-tillage practice are used to achieve advantages of lower draft requirement, better soil breakup and more efficient inversion and trash mixing. The study was aimed at development of three types of rotary blades for strip-tillage (namely, C-type, L-type, and RC-type) in order to reduce the energy requirement for tillage by optimizing the parameters which affect the cutting force of the rotary blades. For this reason the cutting force of the rotary blades and the equations for its surface area per unit volume of soil tilled as well as cutting angles were determined and computer programs to solve these equations were developed. Blade geometrical dimensions corresponding to the minimum and optimum blade surface area per unit volume of soil tilled and cutting angle were selected using the programs to fabricate the rotary blades. The developed and fabricated blades were evaluated in soil bin on the basis of specific work requirement. Investigations were carried out at three levels of number of blades per flange (2, 4, and 6 blades per flange), three levels of forward speed (1.4,2.5, and 3.6 km/h), and three levels of rotational velocity (110, 165, and 244 rpm). It was found that RC-type blade with less specific work requirement and more volume of soil tilled per bite had better performance than other blades. Specific work requirement increased with increase in number of blades per flange and rotary speed, while it reduced by increasing the forward speed. Specific work had an exponential relation with bite length, whereas linear relationship was observed with velocity ratio for all the blades tested.