ABSTRAKT

In this study, an experimental investigation of solid propellant combustion instability using a T-Burner setup was performed. For this purpose, an available T-Burner setup was modified and enhanced. A combustion chamber, choked nozzle, measurement instruments, and data acquisition systems form the T-Burner. The modified T-burner setup was operated for a specific non-metallized solid propellant. To obtain the response of the propellant to different excitation frequencies, the natural frequency of the burner was changed by altering the chamber length. Various chamber lengths were tested and several mean pressure values were measured. The effect of the burning surface on pressure fluctuations was also investigated by altering the propellant configuration. Pressure data revealed oscillatory behavior as expected. Post processing was performed on the collected data set to investigate the effect of different frequencies separately on the response of the selected propellant. Combustion instability studies for solid propellants require determination of the response function of the propellant. To realize that objective, the effect of gains and losses to the pressure oscillations had to be identified. So, the growth and the decay rates of pressure fluctuations were needed to calculate the response function of the propellant at a specific frequency. However, the data obtained from the T-burner used with a nozzle combined both the effects of decay and growth. The growth rate is a function of propellant, but the decay rate is only a function of the chamber. Therefore, to separate the decay rate, the growth rate was halved for the same chamber pressure by changing the burning surface. Then, from the difference of measured amplitude values, growth and decay rates were attained for the selected propellant for the frequency and mean pressure values at which the experiments were performed. The response function of the propellant was obtained.