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Since the 1990s, the global wind power industry has developed rapidly, the total installed capacity of wind power continues to increase, and the rated power of wind turbines and the size of blades continue to increase. As of the end of 2012, the maximum single rated power of the wind turbine that has been put into operation was 7.58 MW, and the maximum diameter of the wind turbine was 154 meters. The trend of large-scale wind turbine blade makes the study of blade fatigue become more and more important.
One of the characteristics of the fatigue load is the pulsation of the load, which is mainly caused by the unsteady effects such as turbulence, tower shadow effect and wind shear. Because the trailing edge flap has better high frequency performance, good structure and safety features, and is easier to apply on the wind turbine, it is considered as the most feasible pneumatic control component for reducing the fatigue load of the wind turbine blade. The Sandia National Laboratories in the United States, Delft University of Technology in the Netherlands, and Risø DTU in Denmark have conducted extensive studies on the trailing edge flaps of wind turbine blades, showing that the trailing edge flaps have better load-reducing effects. However, related researches mainly focus on control strategies, aeroelasticity, and implementation methods. There are few studies on the flow conditions near the trailing edge flaps. The aerodynamics analysis in the aeroelastic analysis is mainly solved by quasi-steady methods, ignoring the flap movements. The effect of the constant characteristics.
The researchers of the Institute of Engineering Thermophysics of the Chinese Academy of Sciences have innovatively studied the aerodynamic characteristics of trailing edge flaps using both steady-state and unsteady computational fluid dynamics methods, analyzed their influence on the flow field structure and the mechanism of action, and can be adjusted by trailing edge flaps. Reducing the magnitude of load changes caused by changes in flow to reduce the fatigue load, providing certain references for the practical application of the trailing edge flaps and optimization of control laws, and providing the momentum leaf theory with corrections for simulation of trailing edge flaps and other control components. The basis and direction.
Recently, through related research, researchers have obtained the relative parameters of the optimal parameters of the airfoil trailing edge flap and the influence of different factors, and analyzed its dynamic characteristics, and pointed out the factors that need to be taken into consideration when adjusting the control laws according to specific conditions; For the analysis of the airfoil wake vorticity shown in Fig. 1 and Fig. 2 and the comparison of the dynamic and static trailing edge flap aerodynamic parameters, the definition of the reduced frequency is given using the trailing edge flap length as the feature scale. A new judgment criterion for the unsteady characteristics of flaps; a simulation study of the dynamic trailing edge flaps of wind turbine blades using unsteady computational fluid dynamics method, which can provide reliable guidance for wind turbine fatigue load control; through the wind turbine blade tail The dynamic characteristics of the edge flaps indicate that the impact of the trailing edge flaps on the aerodynamic characteristics of the wind turbine blades is not limited to the trailing edge flaps, and almost the entire blade is affected, with obvious three-dimensional characteristics. Therefore, the traditional momentum-vegetation is needed. The theory makes the necessary corrections, as shown in Figure 3.
The related research results have been published in the Journal of Engineering Thermophysics, and were reported in the Engineering Thermophysics Annual Meeting and the 6th ICPF International Conference.
Flake Graphite is a natural crystalline Graphite . It is shaped like fish phosphorus, and is a six-square crystal system. It is layered and has good properties of high temperature resistance, conduction, heat conduction, lubrication, plasticization and acid and alkali resistance.
Flake graphite is a natural solid lubricant of layered structure, rich in resources and cheap in price.
feature
The flake graphite crystallization is complete, the film is thin and the toughness is good, the materialized performance is excellent, has the good thermal conductivity, the conductivity, the thermal shock resistance, corrosion resistance and so on.
distribution
In December 2015, geological prospectors found a large scale graphite mine in alashan, Inner Mongolia. The total amount of graphite resources was 1. 300 million tons, about 7 of the world's recoverable reserves. 3%, average grade 5. 45%. According to the introduction, such high grade, large-scale Graphite Mineral deposits are rare in China. [1]
In 2013, the U.S. geological survey reported that the global scale of graphite minerals was less than 5 million tons. The discovery was made in alashan, which has a large scale of 703 million tons of graphite in the area of zahan mushi.
classification
Classified according to the carbon content
Like C %, 99.9% High Purity Graphite; Ninety-four percent of "C %" is High Carbon Graphite; 80% "C %" is Medium Carbon Graphite; 50% "C %" is low Carbon Graphite .
Classification by size of granularity
When the particle size is smaller than w38 micropowder graphite.
standard
Scale graphite standard GB T 3518-2008
apply
refractory
Flake graphite is widely used in the treatment of gold industry of advanced refractory materials and coatings. Such as magnesia carbon brick, crucible, etc. Military industrial firework material stabilizer, smelting industrial desulfurization growth agent, light industry lead pen, electric industry carbon brush, battery industry electrode, fertilizer industry catalyst and so on. The flake graphite is deeply processed, and it can produce the graphite milk for lubricant, deformable agent, drawing agent, conductive coating and so on. It can also produce Expanded Graphite for flexible graphite products such as flexible graphite seals and flexible graphite composite products.
dope
The flake graphite as the functional filler of coating is mainly used for anticorrosive coating, fire retardant coating and conductive coating.
As an anticorrosive material, it has anti-rust primer, such as carbon black, talcum powder and oil, which has good corrosion resistance of chemicals and solvents. If you add zinc and yellow to the formula, it is better to rust.
A graphite interlayer compound obtained from Natural Graphite scales as raw materials, chemically or electrochemically treated. Expandable graphite under the condition of heat, swelling volume (up to 300 times) suffocate the flames, at the same time generate inflation, to isolate the flame, delay or interrupt the effect of flame spread, and itself does not burn, good flexibility, high surface energy, intensity of carbonized layer. But the volume and dosage of the expansive body should be suitable. The test shows that the 150um particles, 30% expansion multiples and 5% dosage are the most suitable.
The flake graphite can be directly used as a carbon conductive filler and can be made into a composite conductive filler for conductive coatings. However, due to the large addition of graphite flake, the coating can be brittle and its application is limited. Therefore, measures are taken to further improve the conductivity of graphite and effectively reduce the amount of graphite flake. Our domestic chemical machinery research institute has developed a high temperature and corrosion resistant resin as basic material, with the strong ability of conducting electrostatic entities large flake graphite flake as the main aggregates, with high intensity of ontology Good abrasion resistance.
The anti - deformation cracking - good short - cut fiber material is a solvent - free thick film conductive coating. The coating has the characteristics of anti-corrosive media penetration, small residual stress, good anti-matrix deformation, stable construction performance and long - term conductive static. Can be used in oil tank inner wall guide electrostatic coating. With electroless plating technique, according to the data of graphite powders metallized, such as copper, nickel, silver, such as the preparation of composite conductive filler, with 30% of the amount used in conductive coating, not only its conductivity is very good, and further improve corrosion.
Flake Graphite
Flake Graphite,Graphite Sheets,Natural Flake Graphite,Medium Carbon Graphite
Fengcheng Ruixing Carbon Products Co., Ltd , http://www.lnfcrxts.com