Power Input of High-Speed Rotary Impellers

This study aims to optimize the design parameters of a vertical axis wind turbine using design of experiments (DOE). Response surface methodology combined with desirability optimization was used to optimize multiple parameters such as the chord length, number of blades, aspect ratio, and pitch angle. The range of contributing parameters was selected using one factor at a time (OFAT) approach, and the performance parameters were evaluated by applying the double multiple streamtube theory. Datasets retrieved from the Q-Blade open-source software were employed in the DOE to determine the optimal configurations. Based on response surface investigation, a quadratic model was established and the accuracy of the model was determined by applying analysis of variance, goodness of fit, normal plot of residuals, and R-squared values. The optimized chord length, number of blades, pitch angle, and aspect ratio were 0.546 m, 03, −2.82°, and 0.808, respectively. The maximum power coefficient of 0.45 was obtained at a tip speed ratio of 3 from the optimized design parameters. The analysis revealed an increase of approximately 8.43% in the maximum power coefficient of the proposed wind turbine. A 3D unsteady computational fluid dynamics model along with Reynolds-Averaged Navier-Stokes equations were utilized to verify the obtained results, and a maximum difference of less than 1.5% was found. A standard H-rotor Darrieus configuration obtained from the OFAT approach was also tested at different wind speeds for comparison. The analysis revealed that when the wind speed was less than 3.85 m/sec, the standard Darrieus produced no power; however, the self-starting speed of the optimized VAWT was as low as 3.22 m/sec. This novel design methodology provides guidelines for obtaining optimum design configurations and can help in achieving high-fidelity analysis in the early design phase.

Energy efficiency study on axial flow impellers

Acoustic characteristics of a rocket combustion chamber: Radial baffle effects

Paclitaxel-Coated Balloon for the Treatment of Small Vessel In-Stent Restenosis: A Subgroup Analysis of the AGENT IDE Randomized Trial.

The paper deals with the description and results of experimental investigation of spatial distribution of kinetic energy of turbulence in a cylindrical system with one or two standard turbine impellers on the same shaft and with radial bafflers at the vessel wall. The time-averaged specific kinetic energy of turbulence of agitated liquid is measured with a stirring-intensity-meter (SIM) consisting of mechanical-piezoelectric sensor and an auxiliary electronic device for processing the scanned fluctuation signal (the SIM calibration was carried out by means of a lasser-doppler anemometer). The measurements were performed in a model vessel of diameter D = 350 mm, in the range of values of Reynolds number for mixing ReM ∈ <1.2.103, 1.06.105> and relative size of impeller and vessel d/D = 0.286 in the single-phase and two-phase system (air was blown into the system through a sparger ring under the lower impeller). It follows from the measured and processed results that the spatial distribution of mean specific kinetic energy of turbulence in systems wit turbine impellers is considerably influenced by the amount of blown air: the mean specific kinetic energy of turbulence decreases with growing volumetric flow rate of air in the stream streaking from blades of rotating impeller, and, in the region outside this stream, it significantly increases.

A small wind turbine blade was designed and optimized in this research paper. The blade plays an important role, because it is the most important part of the energy absorption system. Consequently, the blade has to be designed carefully to enable to absorb energy with its greatest efficiency. The main objective of this paper is to optimized blade number and selection of tip speed ratio corresponding to the solidity. The power performance of small horizontal axis wind turbines was simulated in detail using blade element momentum methods (BEM). In this paper for wind blade design various factors such as tip loss, hub loss, drag coefficient, and wake were considered. The design process includes the selection of the wind turbine type and the determination of the blade airfoil, twist angle distribution along the radius, and chord length distribution along the radius. A parametric study that will determine if the optimized values of blade twist angle and chord length create the most efficient blade geometry. The 3-bladed, 5-bladed and 7-bladed rotor achieved maximum values of Cp 0.46, 0.5 and 0.48 at the tip speed ratio 7, 5 and 4 respectively. It was observed that using BEM theory, maximum Cp varied with strongly solidity and weakly with the blade number. The studies showed that the power coefficient increases upto blade number B = 5, while the blade number if increased above 5 then the power coefficient decreases at operating pitch angle equal to 3°. Highest Cp would have solidity between 4% to 6% for number of blade 3 and design point tip speed ratio of about "7". Highest Cp would have solidity ranging from 5% to 10% for number of blade 5 and 7 and design point tip speed ratio of about 5 and 4 respectively.

This paper describes a series of systematic experimental studies conducted to optimize the performance of a MAV scale cycloidal rotor. Parametric studies were performed to study the effects of blade airfoil section, blade pitching amplitude, asymmetric pitching, location of blade pitching axis and number of blades (at constant solidity) on the performance of the cycloidal rotor. Higher blade pitch angles were found to improve thrust and increase the power loading (thrust per unit power) of the cycloidal rotor. Asymmetric pitching, with a higher pitch angle at the top than at the bottom of the circular blade trajectory, produced better power loading. The optimum pitching axis location was observed to be around 25-35% of the blade chord. For a constant solidity, the rotor with lesser number of blades produced higher thrust and a 2-bladed rotor had the best power loading. Using the results from these parametric studies, an optimized cycloidal rotor with a significantly improved power loading over a conventional MAV rotor was developed.

The main objective of this paper is to model the power coefficient in order to optimize the design of a horizontal axis wind turbine rotor to ensure the optimum aerodynamic power production, based on statistical Design of Experiment (DOE). Sophisticated aerodynamics of the wind turbine and blade geometry is discussed and used to generate the optimum chord and twist distribution of the rotating blades. The dependent variables of the power coefficient are found as the pitch angle, number of blades, and chord and twist distribution. A nonlinear model of the power coefficient based on the dependent variable and their interactions is investigated with the adoption in a 2K factorial design. The significance of the variables as well as the power coefficient model is ensured by the analysis of variance table and scree plots. Interaction plots revealed that the high value of pitch angle and low value of number of blades has the dominant contribution on the power coefficient, while chord and twist distribution is less significant. The results obtained can be used for feasibility study, optimization, and control of the wind turbine control strategy is feasible and results are verified through simulation.

This study aims to optimize and investigate small horizontal-axis wind turbine blades at low wind speeds. The objective of this study is to explain the design method based on BEM theory for 0.2 m blade rotors with constant, variable, and linear chord with twisted blade geometry. MATLAB and Xfoil programs were used to apply BEM principles on wind turbines with SG6043 airfoil. Numerical and experimental studies were carried out to examine the impact of rotor solidity values from 0.057 to 0.207 and the number of blades from 3 to 7. The experimental blades were developed using a 3D printing additive manufacturing technique. The rotors were investigated in an open wind tunnel at wind speeds ranging from 2 to 8 m/s. The initial investigation range included tip speed ratios from 2 to 8 and angles of attacks from 2° to 20°. Subsequently, these parameters were varied in Matlab and Xfoil software to optimization and investigate the power coefficient, blade geometry, number of blades, and blade pitch angle. It was found that a rotor solidity of 0.055–0.085 displayed better performance.

Agitation is one of the greatest challenges in the computer simulation, which is a common operation in mixer–settlers. In the present work, hydrodynamic characteristics of delta impeller pump–mixers have been studied using computational fluid dynamics (CFD) simulations. Sliding mesh approach has been used for the modeling of interaction between static tank and rotating impeller. Standard k–ε turbulence model was adopted. The effect of different geometrical parameters including off‐bottom clearance, impeller diameter, number of blades and height of suction orifice on suction head and power consumption characteristics has been investigated. Low off‐bottom clearance and high suction orifice location were found beneficial to suction increase without extra power input. Scale‐up study has also been carried out at two different vessel sizes. CFD simulation results have been validated and agree with literature and experimental data. Optimum geometry of pump–mixer has been proposed, and new delta impeller designs have been proved better than the original one in pumping capacity. Scale‐up study shows a close agreement of power number and head number of different geometric scales and confirms the validity of CFD simulation in scale‐up of the delta impeller for industrial‐scale application. Copyright © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

The study deals with analysis of the process characteristics of agitated system with a pitched blade impeller and radial baffles (impeller power input and impeller pumping capacity) under turbulent regime of flow of agitated batch. Original experimental data are compared with results of CFD simulation in a pilot plant mixing system published in literature.

Fixed wing Micro Air Vehicles (MAVs) are widely powered by miniature brushless DC motors and mini propellers. These motors have low efficiencies in the MAVs’ operating range; hence consume more power and penalizing the endurance of MAVs flight. Mini propellers also suffer with lower efficiencies due to low Reynolds number effect compared to bigger propellers. Based on the power requirement of MAV’s; generally two bladed different size propellers are used to power these MAVs. Effect of Propeller slipstream wash on the lift generating wings is significant and it is well reported for bigger propellers. The strength of slipstream wash depends on the number of blades, diameter of the propeller, rotational speed, flight speed and trajectory. The effect of slipstream wash could be lowered by increasing the number of blades and with smaller diameter propellers. CSIR-NAL has designed, developed, and fabricated, efficient, 6inch diameter, two and three blade, light-weight, mini propellers using latest state of the art technological advancements for CSIR-NAL fixed wing MAV code named as Black Kite. Apart from this, these propellers are assessed for its realistic propulsive efficiencies using CSIR-NAL configured sophisticated precision test bench manufactured and supplied by M/s MAGTROL, Switzerland. The specialty of this test bench is that it can measure thrust, propellers shaft torque, input power and rotational speeds simultaneously. In the present study CSIR-NAL developed 6 inch diameter two and three bladed propellers of identical plan form are compared for their performance. The three bladed propellers generate 30% higher thrust by marginal weight and efficiency penalty, whereas the noise levels are reduced.

<p>Papillomas developed on Cox-2deltaE mice have a significantly increased percentage of small vessels and a significantly decreased percentage of (medium-sized + large-sized) vessels when compared to papillomas from littermate control Cox-2fl/fl mice. Vessel size analysis was performed with the Definiens' Tissue Studio program to determine vessel sizes from papillomas (n = 9) from Cox-2deltaE mice, papillomas (n = 19) from their littermate Cox-2fl/fl mice, papillomas (n = 9) from Cox-2deltaM mice, and papillomas (n = 10) from their Cox-2fl/fl littermate mice. Parameters were set to distinguish small vessels (<100µm2), medium-sized vessels (100-1000µm2), and large vessels (>1000µm2). The graph shows the vessel size distribution of small, medium-sized and large vessels in papillomas from each of the four cohorts. The percentage of small vessels in papillomas of Cox-2deltaE mice was significantly increased when compared to the percentage of small vessels in papillomas of their Cox-2fl/fl littermates (p = 0.003), and the percentage of (medium-sized + large vessels) was correspondingly reduced (p = 0.002). In contrast, vessel size distribution did not differ for papillomas from Cox-2deltaM mice and their Cox-2fl/fl littermates. Data were analyzed using an unpaired Student's t test. Error bars are SD. * indicates p<0.05.</p>

The paper deals with the experimental study of the indicating particle circulation in a liquid mechanically agitated with two high-speed impellers (two standard turbine impellers or a lower standard turbine and upper six inclined (at 45°) plane blade impeller) on the same shaft in a slender vessel (its height equals double of the vessel diameter) equipped with four radial baffles at its walls under the turbulent flow regime of agitated charge. The visual method of observation of the indicating particle is used to investigate the model system. Four types of the particle circulation are examined: its circulation in the lower part of the system (pumping effect of the lower impeller), its circulation in the upper part of the system (pumping effect of the upper impeller), and the exchangeable circulation between the upper and lower part of the system and vice versa. It follows from the obtained average data of the above-mentioned circulations that the homogeneous circulation of charge in the whole system is reached providing the vertical distance of the high-speed impellers is equal to at least double of their diameter, their pumping capacities being approximately double compared to those reached in the system with one impeller where the off-bottom liquid level height is equal to the vessel diameter. It follows from the comparison of two arrangements, when the upper high-speed impeller pumps liquid either upwards or downwards, that the homogeneous circulation of all the charge agitated is attained in the first of both the cases compared.

In the present paper, a numerical study has been investigated by using computational fluid dynamics (CFD) to analyze pressure, head, head coefficient, pressure coefficient, input power, and volume fraction of cavitation at three cases of simulation in which each one has constant parameters; however, with modifying number of blades which is changed from five to sixteen. The constant parameters are rotating speed, volume flow rate, mass flow rate, outlet diameter, suction specific speed Nss, Reynolds number and NPSHr. These parameters have been fixed to have the same conditions for each case. The shear stress transport (SST) turbulence model has been used to inspect a steady state incompressible flow through centrifugal pump numerically. The simulation has done by using ANSYS®, Vista CPDTM Release 15.0. The results are plotted and discussed to describe and find a relation among cavitation, pump behavior, and variation of blade numbers at constant conditions. The results show a strong relation among increasing blade numbers, centrifugal pump performance and reducing pump cavitation.