| The objective of this research was to understand the dynamic characteristics of the pulse combustion device. The experimental apparatus consisted of a gas fired pulse combustion water heater. A computer simulation program was developed to predict the pulsations in the system and the exhaust noise. The simulation model was first based on the Helmholtz resonator theory in conjunction with the anechoic termination. Comparisons of the predicted results with the measurements on the experimental unit showed good quantitative agreement. Next the mathematical model was extended by viewing the gas column in the neck as a continuous column of compressible gas, employing a finite element model. This relaxed the assumption made in the previous model that the gas column length must be appreciably less than the wavelength of sound of the hot combustion gas. In addition, the anechoic termination was lifted. The finite element modeling of the neck enabled the model to predict the exhaust noise. The predicted pulsations and the exhaust noise showed good agreement with the measurements.; The mathematical models take into account the combustion dynamics, heat release, re-ignition phenomenon, flame front oscillation and flow through the flapper valves. The simulation program has the ability to study the influence of the burner design parameters such as combustion chamber volume, decoupling chamber volume, combustion chamber number and arrangement, pulse tube diameter and length, exhaust pipe diameter, flapper valve dimensions etc. |
