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 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.

scholarly journals Inclusion of velocity gradients in the Unno solution for magnetic field diagnostic from spectropolarimetric data

2010 ◽  
Vol 6 (S274) ◽  
pp. 291-294
Author(s):  
Guillaume Molodij ◽  
Véronique Bommier
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Vertical Velocity ◽  
Velocity Gradient ◽  
Coming Out ◽  
The Sun ◽  
Velocity Gradients ◽  
Vertical Velocity Gradient

AbstractWe present an extension of the Unno-Rachkovsky solution that provides the theoretical profiles coming out of a Milne-Eddington atmosphere imbedded in a magnetic field, to the additional taking into account of a vertical velocity gradient. Thus, the theoretical profiles may display asymmetries as do the observed profiles, which facilitates the inversion based on the Unno-Rachkovsky theory, and leads to the additional determination of the vertical velocity gradient. We present UNNOFIT inversion on spectropolarimetric data performed on an active region of the Sun with the french-italian telescope THEMIS operated by CNRS and CNR on the island of Tenerife.

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.

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 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.

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