AN ACTIVE CONTROL MECHANISM TO ENHANCE AND PARAMETRICALLY STUDY A MULTIFUEL, RIJKE-TYPE, PULSE COMBUSTOR

An active control mechanism has been developed to study the effect of an actively controlled acoustic field on the characteristic parameters of a practical combustion system, This mechanism has been used to att enuate and enhance the combustion instabilities in a multi-fuel, Rijke -tube combustor, The main parameters for this control are discussed in both theory and application on the combustion process, Performance ch aracterization as a function of important reactor and control system p arameters for the control schemes developed, using either external lou dspeakers or inline fuel modulation,are presented, The effect of the c ontrol mechanisms on the combustion process is studied by investigatio n of the changes in flame structure and heat transfer to the reactor w alls. The results show that the burner position inside the Rijke-tube combustor is an important parameter for development and implementation of an effective control mechanism. Implementation of the control mech anism on a two-phase combustion system showed that the heat transfer t o the wall of the combustor increased as much as 26% for oscillating c onditions with a sound-pressure level of 150 dB (re: 20 mu Pa) over th e non-oscillating value, along with an increase of temperature and mix ing. The results from the implementation of the control mechanism on g aseous and liquid fuel showed a changed flame structure. The effects o f controllable pressure modes on the flame structure are significant. In general the flame height decreased with oscillation and increased s ound-pressure level indicating a more compact and efficient combustion process. (C) 1997 Institute of Noise Control Engineering.