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Effect of Prefilmer Edge Thickness on Spray Characteristics in Prefilming Airblast Atomizer
( Naoki Katagata ),( Toshihiro Sakaki ),( Takahiro Okabe ),( Takao Inamura ),( Koji Fumoto ),( Minori Shirota ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-
A prefilming airblast atomizer is a fuel injector used in aircraft gas turbines. The atomization mechanism of the atomizer is well known. After injection, the liquid homogeneously wets the prefilmer surface, and flows down to the prefilmer edge in the form of a liquid film that is sheared by the high-speed air stream. The accumulated liquid at the prefilmer edge is sheared by the air and disintegrated into the bag-shaped liquid framed by a thicker rim. The bag-shaped part of the structure bursts into fine droplets. The rim is stretched and fragments into two elongated ligaments that disintegrate into larger droplets than those generated by bag-shaped disintegration. We focused on the effect of the prefilmer edge thickness on the breakup phenomena of the liquid film and the spray characteristics. Our previous study showed that there is a correlation between the edge thickness and the breakup length and breakup frequency. The objective of this study is to clarify the effect of the prefilmer edge thickness on the spray characteristics such as the Sauter mean diameter (SMD) and the spray generation frequency. The SMD at three prefilmer edge thicknesses (160, 500, and 2000 ㎛) under various conditions were observed using a high-speed camera and an image processing technique. The measurement position from the prefilmer edge was widely varied. The fast Fourier transformation (FFT) analysis was also conducted to evaluate the periodicity of the SMD. The experimental results showed that the SMD increases as the prefilmer edge becomes thicker. In the wake region of the edge, the FFT analysis showed that the increase in prefilmer edge thickness causes the transition of the maximal power spectrum to a lower frequency (i.e. less than 100Hz) due to the larger volume of a liquid accumulation attaching to the edge.
Oh, Seung Won,Okabe, Toshihiro 한국목재공학회 2001 목재공학 Vol.29 No.3
In order to effectively use the waste wood, two types of woodceramics chip tile were made from woodceramics chip, gravel, zeolite and additions. The woodceramics chip was made from branch of apple tree (Malus pumila Mill.) Snow melting property, bending strength and compressive strength of woodceramics chip tile were tested according to the mixing rate of woodceramics chip. Snow melting properties of woodceramics chip tile increased after additions treatment but mechanical properties were reduced significantly after additions treatment. The results indicate that the additions are effective for snow melting property but negative effect on mechanical properties.
Oh, Seung Won,Hirose, Takashi,Okabe, Toshihiro 한국목재공학회 2000 목재공학 Vol.28 No.4
A new porous carbon material $quot;woodceramics$quot; was developed by carbonizing wood or woody materials impregnated with thermosetting resin. Steamed board and non-steamed board were made from thinned small log of Aomori Hiba (Thujopsis dolabrata S. et. Z. var. hondae M.). They were impregnated with phenol resin and sintered in a vacuum furnace at 650℃. In this paper, the manufacturing method of woodceramics and changes of dimension, weight and compressive strength were investigated. The changes of dimension, weight and compressive strength depend on the types of board and density.
Study on sintering process of woodceramics from the cashew nutshell waste
Kieu Do Trung Kien,Phan DinhTuan,Toshihiro Okabe,Do Quang Minh,Tran Van Khai 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.6
In this study, the sintering mechanism of woodceramics (WCs) from cashew nut shell waste (CNSW) was studied by analyzingchemical reactions and structural changes during the sintering process of of CNSW powder, liquefied wood and green bodiesof WCs at 900 oC for 60 minutes in the CO2 atmosphere. The chemical and structural properties of the products wereinvestigated by X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared (FTIR), and scanning electronmicroscope (SEM). The results showed that the decomposition reactions of liquefied wood and CNSW occurred simultaneouslyto form the hard carbon and the soft carbon at high temperature. The sintering mechanism of WCs has been presented.