Abstract
The aim of this paper is to grasp the occurrence condition and the vibration behavior of combustion oscillation as the fundamental study of control of combustion oscillation. Here, combustion oscillation is treated as one-dimensional phenomenon, and pressure and flow velocity fluctuations are analyzed. Combustion chamber is divided into three regions, that is, the region of non-reacted gases, the region of reacted gases, and the reacting zone. In these regions, basic equations are derived from the law of conservation of mass, law of conservation of momentum, law of conservation of energy considering heat quantity, equation of state of ideal gas. In this paper, the response time delay between the response and the generation of heat is introduced considering the structure of the flame. As a result, the relation between the equivalent ratio and the time delay is derived. Analyzing the complex eigenvalues, damping and frequency of the vibration are investigated. Simulation studies are performed to investigate the stability area, taking the length of combustion chamber, the position of reacting zone, the equivalent ratio, the preheat temperature and so on as parameters. To investigate the stability area, the experiments are also performed by making the simple experimental apparatus. The predominant frequencies and the vibrational modes are investigated experimentally, varying the length of combustion chamber, the position of reacting zone, the equivalent ratio, the flow volume of gas and air. It is seen that the analytical and experimental results coincide qualitatively.
