Extension of a Helicoidal Vortex Model to Account for Blade Flexibility and Tower Interference

2006 ◽  
Vol 128 (4) ◽  
pp. 455-460 ◽  
Author(s):  
Jean-Jacques Chattot
Keyword(s):  
Experimental Data ◽  
Renewable Energy ◽  
Wind Tunnel ◽  
Vortex Method ◽  
Flow Speed ◽  
National Renewable Energy Laboratory ◽  
Incoming Flow ◽  
Bending Moments ◽  
Vortex Model ◽  
Potential Sources

The unsteady vortex method has been extended to account for blade flexibility and tower interference. These are two potential sources of unsteadiness of the flow past a wind turbine blade. The cases presented correspond to an incoming flow speed V=5m∕s and low yaw angles and V=8, 10, and 12m∕s and zero yaw. Comparisons of the root flap bending moments predicted by the model with the National Renewable Energy Laboratory (NREL) experimental data indicate that the NREL blades designed for the wind tunnel campaigns are quite rigid and that the tower interference is responsible for unsteadiness that is well captured by the model for zero yaw as well as for yaw of 5, 10 and 20deg.

Model Statistika Prediksi Energi Surya Dengan Menggunakan Autoregresif Integrated Moving Average (ARIMA)

Jurnal MIPA ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 181
Author(s):  
Imriani Moroki ◽  
Alfrets Septy Wauran
Keyword(s):  
Renewable Energy ◽  
Solar Energy ◽  
Moving Average ◽  
Arima Model ◽  
Solar Irradiation ◽  
Energy Sources ◽  
Energy Potential ◽  
Good Design ◽  
Potential Sources ◽  
The Common

Energi terbarukan adalah salah satu masalah energi paling terkenal saat ini. Ada beberapa sumber potensial energi terbarukan. Salah satu energi terbarukan yang umum dan sederhana adalah energi matahari. Masalah besar ketersediaan energi saat ini adalah terbatasnya sumber energi konvensional seperti bahan bakar. Ini semua sumber energi memiliki banyak masalah karena memiliki jumlah energi yang terbatas. Penting untuk membuat model dan analisis berdasarkan ketersediaan sumber energi. Energi matahari adalah energi terbarukan yang paling disukai di negara-negara khatulistiwa saat ini. Tergantung pada produksi energi surya di daerah tertentu untuk memiliki desain dan analisis energi matahari yang baik. Untuk memiliki analisis yang baik tentang itu, dalam makalah ini kami membuat model prediksi energi surya berdasarkan data iradiasi matahari. Kami membuat model energi surya dan angin dengan menggunakan Metode Autoregresif Integrated Moving Average (ARIMA). Model ini diimplementasikan oleh R Studio yang kuat dari statistik. Sebagai hasil akhir, kami mendapatkan model statistik solar yang dibandingkan dengan data aktualRenewable energy is one of the most fomous issues of energy today. There are some renewable energy potential sources. One of the common n simple renewable energy is solar energy. The big problem of the availability of energy today is the limeted sources of conventional enery like fuel. This all energy sources have a lot of problem because it has a limited number of energy. It is important to make a model and analysis based on the availability of the energy sources. Solar energy is the most prefered renewable energy in equator countries today. It depends on the production of solar energy in certain area to have a good design and analysis of  the solar energy. To have a good analysis of it, in this paper we make a prediction model of solar energy based on the data of solar irradiation. We make the solar and wind enery model by using Autoregresif Integrated Moving Average (ARIMA) Method. This model is implemented by R Studio that is a powerfull of statistical. As the final result, we got the statistical model of solar comparing with the actual data

The Effects of Heat Treatment on the Chemical Alterations of Oak Wood

2016 ◽  
Vol 688 ◽  
pp. 44-49 ◽  
Author(s):  
Iveta Čabalová ◽  
František Kačík ◽  
Tereza Tribulová
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Performance Liquid Chromatography ◽  
Renewable Energy ◽  
Liquid Chromatography ◽  
Thermal Treatment ◽  
High Performance ◽  
Treated Wood ◽  
National Renewable Energy Laboratory ◽  
Oak Wood

Samples prepared from oak (Quercusrobur L.) wood were exposed to heat treatment at temperatures of 160, 180, 200 and 220 oC for 3, 6, 9 and 12 hours. In both untreated and thermally treated wood there were determined extractives and lignin by National Renewable Energy Laboratory (NREL) procedures, cellulose by Seifert's method, holocellulose according to Wise, hemicelluloses as difference between holocellulose and cellulose. Monosaccharides were determined by high performance liquid chromatography (NREL).The results show that hemicelluloses are less stable at thermal treatment than cellulose. The amounts of lignin and extractives rose by increasing both temperature and time of the treatment while the amounts of hemicelluloses decreased. Thermal treatment also resulted in significant decreases of the yields of non-glucosic saccharides. Degradation of carbohydrates can cause the deterioration of mechanical properties of wood.

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

scholarly journals Avaliação dos recursos eólicos simulado no estado do Ceará: um estudo de caso para o El Niño 97/98 e para La Niña 98/99

2014 ◽  
Vol 29 (1) ◽  
pp. 139-152 ◽  
Author(s):  
Luiz Martins de Araújo Júnior ◽  
Emerson Mariano da Silva ◽  
Alexandre Araújo Costa ◽  
Domingo Cassain Sales ◽  
Francisco da Chagas Vasconcelos Junior ◽  
...  
Keyword(s):  
Renewable Energy ◽  
El Niño ◽  
El Nino ◽  
La Niña ◽  
National Renewable Energy Laboratory ◽  
Regional Modelling ◽  
La Nina ◽  
Modelling System

Este estudo foi desenvolvido no intuito de avaliar o potencial eólico do estado do Ceará nos períodos chuvoso e seco em eventos de El Niño e La Niña. Para isso é utilizado o modelo de área limitada, Regional Modelling System (RAMS 6.0), forçado pela reanálise ERA-Interim, para simular a densidade do ar e a velocidade do vento em diferentes níveis atmosféricos. Para avaliação do desempenho do modelo, os dados simulados de velocidade do vento são comparados com dados observados, a 10 m da superfície, de estações climatológicas do Instituto Nacional de Meteorologia (INMET), por meio de gráficos e um conjunto de índices estatísticos. Adicionalmente, mapas mensais de velocidade média a 50 m da superfície foram feitos, classificando o potencial eólico de acordo com o National Renewable Energy Laboratory (NREL). Os resultados apresentados para avaliação do desempenho do modelo mostraram que apesar do modelo superestimar os dados observados, o índice de concordância ou Wilmott e o coeficiente de correlação apresentam valores que variam de moderado (0,40 < r < 0,69) a forte (0,70 < r < 0,89). Através do conjunto de índices estatísticos ainda foi possível extrair que nos semestres mais chuvosos e/ou em período de ocorrência do fenômeno La Niña o desempenho do modelo é melhor. Com relação à avaliação do potencial eólico, notou-se que em ocorrência de ENOS positivo há uma condição mais favorável de geração de energia do que em evento de ENOS na fase fria, principalmente na região litorânea do estado do Ceará. Com isso, conclui-se que o desempenho do modelo foi satisfatório, mostrando ser uma possível ferramenta para futuras rotinas operacionais de previsão dos recursos eólicos do Estado.

scholarly journals Accurate Measurements of Wall Shear Stress on a Plate with Elliptic Leading Edge

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2682 ◽  
Author(s):  
Guang-Hui Ding ◽  
Bing-He Ma ◽  
Jin-Jun Deng ◽  
Wei-Zheng Yuan ◽  
Kang Liu
Keyword(s):  
Shear Stress ◽  
Wind Tunnel ◽  
Wall Shear Stress ◽  
Leading Edge ◽  
Reynold Number ◽  
Micro Electro Mechanical System ◽  
Flow Speed ◽  
Silicon On Insulator ◽  
Micro Sensor ◽  
Wall Shear

A micro-floating element wall shear stress sensor with backside connections has been developed for accurate measurements of wall shear stress under the turbulent boundary layer. The micro-sensor was designed and fabricated on a 10.16 cm SOI (Silicon on Insulator) wafer by MEMS (Micro-Electro-Mechanical System) processing technology. Then, it was calibrated by a wind tunnel setup over a range of 0 Pa to 65 Pa. The measurements of wall shear stress on a smooth plate were carried out in a 0.6 m × 0.6 m transonic wind tunnel. Flow speed ranges from 0.4 Ma to 0.8 Ma, with a corresponding Reynold number of 1.05 × 106~1.55 × 106 at the micro-sensor location. Wall shear stress measured by the micro-sensor has a range of about 34 Pa to 93 Pa, which is consistent with theoretical values. For comparisons, a Preston tube was also used to measure wall shear stress at the same time. The results show that wall shear stress obtained by three methods (the micro-sensor, a Preston tube, and theoretical results) are well agreed with each other.

scholarly journals Sensitivity study of diffuser angle and brim height parameters for the design of 3 kW Diffuser Augmented Wind Turbine

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Michał Lipian ◽  
Maciej Karczewski ◽  
Krzysztof Olasek
Keyword(s):  
Numerical Model ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Sensitivity Study ◽  
Flow Speed ◽  
Diffuser Angle

AbstractThe Diffuser Augmented Wind Turbine (DAWT) is an innovative mean to increase the power harvested by wind turbine. By encompassing the rotor with a diffusershaped duct it is possible to increase the flow speed through the turbine by about 40-50%. The study presents the development of a numerical model and its validation by the experiments performed in the wind tunnel of the Institute of Turbomachinery, TUL. Then, the numerical model is used for the geometry sensitivity study to optimize the shape of a diffuser. The paper presents that the DAWT technology has the potential to even double the power outcome of wind turbine when compared to a bare rotor version.

Study on the Bubble Dynamics and the Exciting Force in a Bended Pipe Based on BEM

2016 ◽  
Author(s):  
Y. L. Liu ◽  
Z. L. Tian
Keyword(s):  
Numerical Model ◽  
Potential Theory ◽  
Bubble Dynamics ◽  
Flow Speed ◽  
Exciting Force ◽  
Incoming Flow ◽  
Bubble Motion ◽  
Dynamics Model ◽  
Pipe Surface ◽  
Direction Change

Nonlinear bubble dynamics in a pipeline and its exciting force are investigated by a numerical model based on BEM. The bubble motion is one of the main causes that the pipeline vibrates and generates noise in modern ships. The numerical bubble dynamics model is established under the incompressible potential theory. Bubble motion with different incoming flow in a bended pipe is simulated. We found that the bubble develops jet when it passes by the bend, and adjoin to the pipe surface in the side of the fillet center. The pulsation and the direction change of the bubble apply an exciting force on the pipe which has a positive correlation with the incoming flow speed and may lead vibration and noise.

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