二次元バルブレスパルス燃焼器の音響特性の実験的および数値的評価 : 数値解析手法と非燃焼時の音響特性の評価の試み〔熱工学, 内燃機関, 動力など〕

A numerical procedure to predict acoustic characteristics of a two-dimensional valveless pulse combustion system is described in detail, introducing a plane sound wawe approximation. The resonance sound pressure in the combustion chamber is numerically estimated by applying plane sound pressure with various frequencies in the combustion chamber and by synthesizing reflected sounds from both the upstream supply line and downstream exhaust line under the cold and stagnant conditions. In this paper numerical analysis is first performed on a simple Helmholtz-type combustor consisting of a combustion chamber and a tailpipe. Experimental measurements of acoustic characteristics of the combustor are also made. By integrating suitable values for the acoustic parameters, such as the damping factor and reflection coefficient, into the calculation, fine agreement of the numerically predicted resonance characteristics with the experimental measurements is obtained, indicating the usefulness of the proposed numerical approach for examining acoustic characteristics of the practical pulse combustion systems.