Authors: Xian Feng Chen, Y. Zhang, M. Chen, Shao Feng Ren, Xiao L. Song
Abstract: To prevent and control fire and explosion disasters, the premixed methane-air explosion was performed under restricted condition. In the experiment, the high speed schlieren photography system was used to record the flame characteristics and propagation mechanism. At the same time the ion current probe was used to reveal the inner flame structure characteristics. Based on the images of High Speed Schlieren Photography, the flame acceleration and flame structure were discussed in detail. In addition, the flow field characteristic of explosion flame was disclosed clearly. The microscopic evolving process of laminar-turbulent transition was accomplished in the period of flame structure change. As an alternative observation and detect technique, the high speed schlieren photograph system was used to capture flame front microstructure dynamic process precisely. Based on burning chemical and explosive dynamics, the optical measure method can record flame dynamic behavior visually, which further helps to disclose flame microstructure characteristic and the inner dynamic mechanism.
2793
Authors: Wei Gang Yan, Chang Jian Wang, Jin Guo
Abstract: This paper proposes a new image segmentation algorithm to detect the flame image from video in enclosed compartment. In order to avoid the contamination of soot and water vapor, this method first employs the cubic root of four color channels to transform a RGB image to a pseudo-gray one. Then the latter is divided into many small stripes (child images) and OTSU is employed to perform child image segmentation. Lastly, these processed child images are reconstructed into a whole image. A computer program using OpenCV library is developed and the new method is compared with other commonly used methods such as edge detection and normal Otsu’s method. It is found that the new method has better performance in flame image recognition accuracy and can be used to obtain flame shape from experiment video with much noise.
2141
Authors: Gui Zhi Bai, Li Hong Zhang, Shu Qian Chen
Abstract: For the use of boiler flame image analysis to detect the boiler flame combustion stability, when the combustion affected by coal, peaking , improper operation or other effects, the flame appeared short pulsation. In general, the traditional detection methods based on gray scale variance can not avoid the impact of flame pulsation on account of the inaccuracy of the boiler combustion stability detection. This paper presents a flame combustion instability detection method based on neural network and selects multiple features which are directly related to the flame stability as neural network input vector. Experiments show that this method can fight off the tiny ripple influence caused by the impurities combustion or peak and simultaneously, greatly improve the detection accuracy and stability.
390
Authors: Xia Li, Xuan Jun Wang
Abstract: The paper studies the flame spread characteristics of the diesel with safety performance by schlieren technology. The flame of fire spreading of the diesel includes flash fire flame which is blue and main flame which is orange. The main flame spread forward in the reciprocating and pulsatile pattern, while the flash fire flame spread with the level discontinuous pulsatile pattern. The water content in the diesel has notable restriction effect on the speed of the flame spreading, which is decreased with the increasing of the water content. But the micro-emulsified diesel can’t effectively restrain the spread speed when water content is below 3%. The microemulsified diesel whose water content being in the range of 3%~12% could be used in engine.
2515
Authors: Yu Jen Liu, Yen Chang Chen, Pei Hsiu Lan, Tsang Pin Chang
Abstract: As small wind turbines are increasingly used, the assessments of power quality may thus become paramount. Unlike the large-scale wind turbines which are optional required to perform power quality measurements during production certification stage; however the power quality measurements are often neglected in small wind turbines since they are not requested on the certain of national grid codes at low-voltage distribution system level. Considering the high penetrations of small wind turbines may be connected to the future urban electric network, the paper performs the power quality on-site measurements of a horizontal axle small wind turbines. The issues may include the discussion of measurement system structure, the description of measurement method, and the analysis of wind turbine power characteristic, voltage/current trends, harmonics and flicker phenomena. The measured data collected in the study will valuable for the further analysis of power systems connected with the small wind turbines.
329
