Acoustic Model Generation of Heat Source in Rijke Tube

Abstract

Self-excited vibration called the combustion vibration occurs in the combustion apparatus. The vibration and noise adversely affect combustion apparatuses. Therefore, it is necessary to suppress generation of vibration. The purpose of our research is to analyze the mechanism of generating the combustion vibration using a cellular automaton method (abbrev.CA). At first, we conducted experiments and confirmed characteristics of Rijke tube. Next, we established the rule of the CA method. The expansion of the air in the heat source expressed by the vibration of the piston. In the heat source, since the expansion depend on the flow velocity, the particle velocity in the heat source was fed back to the amount of vibration of the piston. Furthermore, we focused on the heat transfer coefficient within 0 Re 1 , and created a model when there is no convection. As a result, it was found that the particle velocity of the heat source including time-delay causes self-excited vibration. Furthermore, the backward flow in the tube and the temperature drop of the heat source suppress the self-excitation. Moreover, we were able to reproduce the experimental result of horizontal Rijke tube. It was also found that positive feedback of sound pressure promotes growth of self-excited vibration, and negative feedback suppresses growth of self-excited vibration.