排序方式: 共有108条查询结果,搜索用时 15 毫秒
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Microgravity experiments of single droplet combustion in oscillatory flow at elevated pressure 总被引:1,自引:0,他引:1
Yasuhiro Ogami Satoru Sakurai Syoichi Hasegawa Mehdi Jangi Hisashi Nakamura Kentaro Yoshinaga Hideaki Kobayashi 《Proceedings of the Combustion Institute》2009,32(2):2171-2178
An experimental study for 1-butanol single droplet flames in constant and oscillatory flow fields was conducted under microgravity conditions at elevated pressure. In the constant flow experiments, flow velocities from 0 to 40 cm/s were tested. Using obtained data of d2, the burning rate constants were evaluated. The burning rate constant in the quiescent condition was also calculated successfully at high pressure by the extrapolation method based on the Frössling relation. In the oscillatory flow experiments, the flow velocities were varied from 0 to 40 cm/s at the frequencies of 2–40 Hz. Results showed that the burning rate constant during the droplet lifetime varied following the quasi-steady relation at 0.1 MPa; however, in the conditions with higher frequencies at 0.4 MPa, the average burning velocity became larger than that for the constant flow case with the velocity equivalent to the maximum velocity in the oscillatory flow. Under the condition where the burning rate constant increased, it was observed that the flame did not sufficiently move back upstream, leading to enhancement of the heat transfer from the flame to the droplet surface. Therefore, the instantaneous burning rate constant increased. To investigate the mechanism of such flame behavior, the ratio of two characteristic times, τf/τD (τf: flow oscillation characteristic time, τD: diffusion characteristic time), were compared. As the flow oscillatory frequency increased, τf/τD becomes smaller. τf/τD also became smaller at high pressure. If τf/τD is small due to the small mass diffusion rate, the droplet flame could not move back to the appropriate position for the minimum velocity in steady flow, leading to an increase of the burning rate constant, especially in the case of higher frequency at high pressure. 相似文献
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A series of dihalodiaryl(acetylacetonato)antimony(V) compounds, (p-Y-C6H4)2SbX2Acac (X=F, Cl, Br; Y=NO2, Cl, H, CH3, CH3O), were prepared. All of these compounds are monomeric and exist in solution as a mixture of two isomers both with chelated hexacoordinate configurations. From the temperature- and solvent-dependent PMR spectra of these compounds, it is concluded that the two isomers are in equilibrium in solution. The assignments of the PMR signals to the isomers were made by considering the effects of solvent and the substituents X and Y on the spectra. 相似文献
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Gohei Yoshida Hideo Kurosawa Rokuro Okawara 《Journal of organometallic chemistry》1977,131(2):309-315
Oxidative addition of ClCH2SCH3 to PtL4 afforded trans-PtL2(CH2SCH3)Cl (Ia, L = Ph3P;Ib, L = MePh2P). Treatment of I with NH4PF6 or Et3OBF4 in CH2C12 gave ionic species, [PtL2(CH2SCH3)]X (II, L = Ph3P, MePh2P, X = BF4, PF6), while similar treatment with MeSO3F in benzene yielded a new type of stable dimethylsulfonium methylide—platinum complex, trans-[PtL2(CH2SMe2)Cl] SO3F (IIIa, L = Ph3P; IIIb, L = MePh2P). Action of H2O2 on Ia gave [Pt(Ph3P)(μ-CH2SCH3)C1]2 (IV) and its triphenylarsine analog, [Pt(Ph3As)(μ-CH2SCH3)C1]2 (V) was prepared in one step by oxidative addition of ClCH2SCH3 to Pt(AsPh3)4. The structural difference between [Pt(Ph3P)(μ-CH2SCH3)C1]2 and Pd(Ph3P)- (CH2SCH3)C1 is discussed in terms of the difference in the ionization potential from d10 to d8 electronic state of metals. 相似文献
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Kentaro Ageishi Takeshi Endo Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1983,21(1):293-300
Polymers of viologen structure were prepared by oxidation of quinoid polymers obtained by the dimerization of alkylene dipyridinium salts with cyanide ion as catalyst. These polymers showed the behavior of polyelectrolytes and redox polymers that turn a deep blue when reduced chemically or electrically. 相似文献
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3-Acetylpyrrolidines are prepared from 5-methyl-5-vinyloxazolidines in a reaction which involves a directed 2-azonia-[3,3]-sigmatropic rearrangement. 相似文献
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Junzo Nokami Toshiyuki Yamamoto Mikio Kawada Mari Izumi Nobuko Ochi Rokuro Okawara 《Tetrahedron letters》1979,20(12):1047-1048
Malonic acid derivatives(gem-dicarboxylic acids) were converted to the corresponding ketones by the electrolysis. The reaction was employed for the synthesis of jasmones. 相似文献
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Takero Teramoto Mikito Deguchi Toshikazu Kurosaki Makoto Okawara 《Tetrahedron letters》1981,22(12):1109-1112
Preparations of optically active N-hydroxytartrimides were achieved. 1,3,4-Trihydroxysuccinimide ester of Z-L-alanine and 1-hydroxy-3,4-diacetoxysuccinimide ester of Z-D-alanine were allowed to react with D,L-alaninate to produce L-L form and D-D form of Z-Ala-Ala-OEt respectively (optical yield 100%). 相似文献