Department of Mechanical Engineering , Fukui University
Department of Aerospace Engineering, Nagoya University
出版者
航空宇宙技術研究所
出版者（英）
National Aerospace Laboratory(NAL)
雑誌名
航空宇宙技術研究所特別資料
雑誌名(英)
Special Publication of National Aerospace Laboratory SP-3
巻
3
ページ
131 - 140
発行年
1984-11
抄録（英）
Numerical simulations of unsteady phenomena in the combustion chamber of an oxyhydrogen rocket motor were made in an attempt to develop a computer code for use in investigating such phenomena as vibrating combustion. The combustion in this system is controlled by diffusion, the effect of which works much slower than sound or pressure waves, so that diffusions are usually solved using the implicit finite difference method for unlimited time step size caused by stability criterion. However, the gases flow so fast, accompanied by unsteady pressure waves, that an explicit method is adopted to solve this problem. The way of modeling the turbulent diffusion combustion is very important in this simulation. The fine structures of turbulence and diffusion flame could not be calculated by a finite difference method because of the limited ability of computers. It is presumed that the size of the space difference should be less than or the same order as that of the small eddies. In the present example of simulation, eddy equations are not solved; rather the reasonable transport coefficients for small eddies are simply used. Chemical reactions are also simplified. The gases assumed consist of three components, i. e., fuel, oxidizer and product. In turbulent diffusion burning, rate constants for chemical reactions are to be smaller than those in premixed gas, for the composition at a lattice point is not exact but averaged. Especially for diffusion combustion, the artificial diffusion included in the finite difference scheme must be smaller than the actual diffusion. A brief estimation shows that the space mesh size should be the same order as the turbulent diffusion coefficient divided by flow velocity. An example of simulation using MacCormack's explicit method is shown, where vibrations appear after ignition, followed by attenuation. The results indicate the possibility of numerical simulation of unsteady phenomena in an oxyhydrogen rocket motor, though it is still necessary to make comparisons with experiments to fix some parameters.
水素酸素ロケット燃焼室内の拡散燃焼シミュレーション
nalsp0003016.pdf
(721.1KB)
