| 共催： |
- ２１世紀ＣＯＥプログラム「動的機能機械システムの数理モデルと設計論」
- 日本航空宇宙学会関西支部「流体力学における微視的アプローチ」研究分科会
|
| 日時： |
2004年04月22日（木） 14：00〜15：30 |
| 場所： |
京都大学大学院 工学研究科 航空宇宙工学専攻 2階 会議室 |
| 講演者： |
Dr. Domenico Giordano (ESTEC-Aerothermodynamics Section, European Space Agency, Noordwijk, The Netherlands) |
| 講演題目： |
The influence of medium compressibility on chemical-reaction rates |
| 講演要旨： |
The present paper addresses the importance of the influence that the compressibility of a chemically reacting gas mixture, quantitatively represented by the divergence of the velocity vector, can have on chemical-reaction rates. The investigation is carried out from the point of view of the macroscopic theory. From considerations of physical consistency, it is shown that the law of mass action introduces an incompatibility when exported to gas-dynamics situations characterized by non-negligible compressibility of the chemically reacting medium. The origin of the incompatibility traces back to the mathematical fact that the law vanishes identically in the asymptotic limit of local chemical equilibrium. The incompatibility is removable if terms proportional to the divergence of the velocity vector are adequately brought into account. Two corrections are considered. One correction, proposed on the base of macroscopic-theory arguments, is proportional to the divergence of the velocity vector through coefficients represented by thermodynamic derivatives of a virtual local chemical-equilibrium composition; a general method to determine these necessary chemical-equilibrium derivatives is described and applied to the cases of dissociating nitrogen and dissociating-ionizing oxygen. The other correction has been taken from the pertinent literature and has been derived according to arguments of chemical/vibrational kinetics. Numerical experiments, concentrating on a quasi one-dimensional inviscid-flow expansion of dissociating-recombining nitrogen and oxygen inside a hypersonic nozzle, are carried out with the purpose of quantifying the influence of compressibility corrections upon chemical-reaction rates based on the law of mass action. Results show non-negligible differences between calculations carried out with and without compressibility corrections and stimulate further investigations on the subject matter. |
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