scholarly journals Multirotor Systems Using Three Shrouded Wind Turbines for Power Output Increase

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Koichi Watanabe ◽  
Yuji Ohya
Keyword(s):  
Wind Turbines ◽  
Power Output ◽  
Total Power ◽  
Vortex Interaction ◽  
Wind Tunnel Experiments ◽  
Significant Saving ◽  
Wind Turbine System ◽  
Output Increase ◽  
Lowered Pressure ◽  
Total Power Output

Brimmed-diffuser augmented wind turbines (B-DAWTs) can significantly increase the performance of the rotor. Multirotor systems (MRSs) have a lot of merits such as significant saving mass and overall cost of the wind turbine system. In the present research, B-DAWTs are studied in a MRS. In wind tunnel experiments, the power output and aerodynamics of three B-DAWTs placed in close vicinity have been investigated. The results show a significant increase of up to 12% in total power output of the MRS with B-DAWTs compared to the sum of the stand-alone (SA) same turbines. The accelerated gap flows between B-DAWTs in a MRS cause lowered pressure regions due to vortex interaction behind the brimmed diffusers and draw more wind into turbines.

Power Augmentation of Shrouded Wind Turbines in a Multirotor System

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Yuji Ohya ◽  
Jumpei Miyazaki ◽  
Uli Göltenbott ◽  
Koichi Watanabe
Keyword(s):  
Wind Turbines ◽  
Power Output ◽  
Bluff Body ◽  
Flow Direction ◽  
Total Power ◽  
Significant Saving ◽  
Vortex Interactions ◽  
Wind Turbine System ◽  
Flow Phenomena ◽  
Circular Disks

Diffuser-augmented wind turbines (DAWTs) can significantly increase the performance of the rotor. Multirotor systems (MRSs) have a lot of merits such as significant saving mass and overall cost of the wind turbine system. A MRS is defined as containing more than one rotor in a single structure. In the present research, DAWTs are studied in a MRS. In wind tunnel experiments, the power output and aerodynamics of two and three DAWTs placed in close vicinity, in side-by-side arrangements, have been investigated, along with circular disks and conventional wind turbines in the same configurations as the MRS. Results show a significant increase of up to 12% in total power output of the MRS with DAWTs compared to the sum of the stand-alone same turbines. The results can be explained by observing the bluff body flow phenomena in the wake interference around the multiple circular disks. Those flow phenomena are due to the accelerated gap flows and those biasing in the flow direction caused by the vortex interactions in the gap.

scholarly journals A New Approach Toward Power Output Enhancement Using Multirotor Systems With Shrouded Wind Turbines

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Ohya Yuji ◽  
Watanabe Koichi
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Power Output ◽  
Vertical Plane ◽  
Total Power ◽  
Plane Normal ◽  
Output Performance ◽  
Wind Turbine System ◽  
Lowered Pressure ◽  
Single Structure

A multirotor system (MRS) is defined as containing more than one rotor in a single structure. MRSs have a great potential as a wind turbine system, saving mass and cost, and showing scale ability. The shrouded wind turbine with brimmed diffuser-augmented wind turbines (B-DAWT) has demonstrated power augmentation for a given turbine diameter and wind speed by a factor of about 2–5 compared with a bare wind turbine. In the present research, B-DAWTs are used in a multirotor system. The power output performance of MRSs using two and three B-DAWTs in a variety of configurations has been investigated in the previous works. In the present study, the aerodynamics of an MRS with five B-DAWTs, spaced in close vicinity in the same vertical plane normal to a uniform flow, has been analyzed. Power output increases of up to 21% in average for a five-rotor MRS configuration are achieved in comparison to that for the stand-alone configuration. Thus, when B-DAWTs are employed as the unit of a MRS, the total power output is remarkably increased. As the number of units for an MRS is increased from two to five, the increase in power output becomes larger and larger. This is because that the gap flows between B-DAWTs in a MRS are accelerated and cause lowered pressure regions due to vortex interaction behind the brimmed diffusers. Thus, a MRS with more B-DAWTs can draw more wind into turbines showing higher power output.

scholarly journals Brief Communication: On the influence of vertical velocity profiles on the combined power output of two model wind turbines in yaw

2017 ◽  
Author(s):  
Jannik Schottler ◽  
Agnieszka Hölling ◽  
Joachim Peinke ◽  
Michael Hölling
Keyword(s):  
Wind Turbines ◽  
Vertical Velocity ◽  
Velocity Gradient ◽  
Power Output ◽  
Velocity Profiles ◽  
Total Power ◽  
Misalignment Angle ◽  
Velocity Gradients ◽  
Total Power Output ◽  
Vertical Velocity Gradient

Abstract. The effect of vertical velocity gradients on the total power output of two aligned model wind turbines as a function of yaw misalignment of the upstream turbine is studied experimentally. It is shown that asymmetries of the power output of the downstream turbine and the combined power of both with respect to the upstream turbine's yaw misalignment angle can be linked to the vertical velocity gradient of the inflow.

scholarly journals Brief communication: On the influence of vertical wind shear on the combined power output of two model wind turbines in yaw

2017 ◽  
Vol 2 (2) ◽  
pp. 439-442 ◽  
Author(s):  
Jannik Schottler ◽  
Agnieszka Hölling ◽  
Joachim Peinke ◽  
Michael Hölling
Keyword(s):  
Wind Turbines ◽  
Power Output ◽  
Wind Shear ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Total Power ◽  
Misalignment Angle ◽  
Total Power Output

Abstract. The effect of vertical wind shear on the total power output of two aligned model wind turbines as a function of yaw misalignment of the upstream turbine is studied experimentally. It is shown that asymmetries of the power output of the downstream turbine and the combined power of both with respect to the upstream turbine's yaw misalignment angle can be linked to the vertical wind shear of the inflow.

scholarly journals Total power output generated during dynamic knee extensor exercise at different contraction frequencies

2000 ◽  
Vol 89 (5) ◽  
pp. 1912-1918 ◽  
Author(s):  
Richard A. Ferguson ◽  
Per Aagaard ◽  
Derek Ball ◽  
Anthony J. Sargeant ◽  
Jens Bangsbo
Keyword(s):  
Power Output ◽  
Accurate Determination ◽  
Knee Extensor ◽  
Mechanical Efficiency ◽  
Muscle Group ◽  
Total Power ◽  
Mechanical Power Output ◽  
External Power ◽  
Power Outputs ◽  
Total Power Output

A novel approach has been developed for the quantification of total mechanical power output produced by an isolated, well-defined muscle group during dynamic exercise in humans at different contraction frequencies. The calculation of total power output comprises the external power delivered to the ergometer (i.e., the external power output setting of the ergometer) and the “internal” power generated to overcome inertial and gravitational forces related to movement of the lower limb. Total power output was determined at contraction frequencies of 60 and 100 rpm. At 60 rpm, the internal power was 18 ± 1 W (range: 16–19 W) at external power outputs that ranged between 0 and 50 W. This was less ( P < 0.05) than the internal power of 33 ± 2 W (27–38 W) at 100 rpm at 0–50 W. Moreover, at 100 rpm, internal power was lower ( P < 0.05) at the higher external power outputs. Pulmonary oxygen uptake was observed to be greater ( P< 0.05) at 100 than at 60 rpm at comparable total power outputs, suggesting that mechanical efficiency is lower at 100 rpm. Thus a method was developed that allowed accurate determination of the total power output during exercise generated by an isolated muscle group at different contraction frequencies.

scholarly journals Performance assessment of a four-air cathode membraneless microbial fuel cell stack for wastewater treatment and energy extraction

2019 ◽  
Vol 116 ◽  
pp. 00093
Author(s):  
Asimina Tremouli ◽  
Pavlos K. Pandis ◽  
Theofilos Kamperidis ◽  
Vassilis N. Stathopoulos ◽  
Christos Argirusis ◽  
...  
Keyword(s):  
Power Output ◽  
Microbial Fuel Cells ◽  
Continuous Operation ◽  
Cod Removal ◽  
Total Power ◽  
Parallel Connection ◽  
Significant Information ◽  
Single Chamber ◽  
In Series ◽  
Total Power Output

A stack of two identical single chamber microbial fuel cells (MFCs) was assessed during using fermentable house hold extract as substrate. The design of the MFC units was based on the single chamber membrane-less technology using four cathode electrodes. The total power output was 492 mW either in series or parallel connection considering a total anolyte volume of 240 cm3. During continuous operation, the COD removal was 80% for each cell and for both operation modes (series and parallel). The electrochemical profiles provided significant information on the behaviour of the stack. During continuous operation, parallel connection is preferred over series connection, as it results to the same power output values, and COD removal but it provides lower internal resistances leading to more stable electrochemical performance behaviour.

Optimal Control and Switching Mechanism of a Power Station With Identical Generators

2017 ◽  
Author(s):  
Fulai Yao ◽  
Qingbin Gao
Keyword(s):  
Optimal Control ◽  
Power Supply ◽  
Power Output ◽  
Total Power ◽  
Power Station ◽  
Efficiency Function ◽  
Novel Approach ◽  
Overall Efficiency ◽  
Total Power Output ◽  
Operating Methods

This paper proposes a novel approach for optimizing the total power output of a generalized power station with identical generators by analyzing the characteristics of the efficiency function. The introduced treatment yields the maximum total power supply and the maximum overall efficiency for the generalized power station. To achieve these, the input factor for each generator is kept the same, and the optimal switch points are selected to be the same efficiency points of two operating methods.

scholarly journals Discussion of Some Myths/Features Associated With Gas Turbine Inlet Fogging and Wet Compression

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Ting Wang ◽  
Jobaidur R. Khan
Keyword(s):  
Entropy Production ◽  
Gas Turbine ◽  
Power Output ◽  
Effective Means ◽  
Weather Conditions ◽  
Total Power ◽  
Water Evaporation ◽  
Water Droplets ◽  
Wet Compression ◽  
Total Power Output

Gas turbine (GT) inlet fogging and overspray (high-fogging) have been considered the most cost-effective means of boosting a GT's total power output, especially under hot or dry weather conditions. The result of employing fogging or overspray is indisputably clear—total power output is increased; however, development of the theory and explanation of the phenomena associated with fogging and overspray are not always consistent and are sometimes misleading and incorrect. This paper focuses on reviewing several interesting features and commonly discussed topics, including (a) entropy production of water evaporation, (b) the effect of centrifugal force on water droplets, and (c) whether water droplets can survive the journey in the compressor and enter the combustor. Furthermore, three turbine myths that fogging/overspray increases the air density in the compressor, reduces the compressor power consumption, and noticeably enhances the GT efficiency are examined and discussed. Some common mistakes in describing the compressor work are identified and corrected. A newly constructed multiphase T–s diagram is used to explain the physics of water droplet evaporation process and corresponding entropy production during wet compression.

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