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Katsumi, Toshiyuki; Yoshida, Yasuhito*; Nakagawa, Ryo*; Yazawa, Shinya*; Kumada, Masashi*; Sato, Daisuke*; Thwe Thwe, A.; Chaumeix, N.*; Kadowaki, Satoshi
Journal of Thermal Science and Technology (Internet), 16(2), p.21-00044_1 - 21-00044_13, 2021/00
Times Cited Count：6 Percentile：40.36(Thermodynamics)The effects of addition of CO
and water vapor on characteristics of dynamic behavior of hydrogen/air premixed flames were elucidated experimentally. By Schlieren photography, wrinkles on the flame surface were clearly observed in low equivalence ratios. The propagation velocity increased monotonically as the flame radius became larger and flame acceleration was found. Increasing the addition of inert gas, the propagation velocity decreased, especially in the case of CO addition. Moreover, the Markstein length and the wrinkling factor decreased. This indicated that the addition of Co or HO promoted the unstable motion of hydrogen flames, which could be due to the enhancement of the diffusive-thermal effect. Based on the characteristics of dynamic behavior of hydrogen flames, the parameters used in the mathematical model on propagation velocity including flame acceleration was obtained, and then the flame propagation velocity under various conditions was predicted.
4P
Kawana, Daichi*; Kuwahara, Keitaro*; Sato, Masashi*; Takagi, Masatoshi*; Aoki, Yuji*; Kogi, Masafumi*; Sato, Hideyuki*; Sagayama, Hajime*; Osakabe, Toyotaka; Iwasa, Kazuaki*; et al.
Journal of the Physical Society of Japan, 75(11), p.113602_1 - 113602_4, 2006/11
Times Cited Count：11 Percentile：56.26(Physics, Multidisciplinary)We report the first X-ray diffraction experiments of PrFeP under high pressure. We discovered a symmetry lowering from cubic to orthorhombic or lower at the metal-insulator transition temperature, accompanied by a jump in the lattice constant, which indicates a first-order phase transition. The superlattice reflections at q=(1,0,0) observed in the low-pressure nonmagnetic ordered phase are found to disappear in the insulating phase. The temperature dependence of the lattice constant and the absence of the superlattice reflections are well explained by taking into account an antiferromagnetic ordering.
