Development of closed-loop active control method for suppression of thermoacoustic instability using radial air micro-jets

Thermoacoustic instabilities present in the combustor of power producing devices are having adverse effects on the performance. To avoid thermoacoustic instabilities, design of control method is very much essential. Design and development of a closed loop control method is a real challenge for combustor. Active control methods are advantageous than passive methods. The characterization of thermoacoustic instability is essential for effective design of control method. The selection of appropriate controller and it's design depends on characterization of thermoacoustic instabilities. In this method the feedback signal acquired from microphone is used to control the flow rate of radial micro-jets. The developed method is implemented effectively to suppress thermoacoustic instabilities in a one dimensional combustor (Rijke tube). The airflow to the radial micro-jets injector was controlled using a control unit which consist of a stepper motor coupled with a needle valve, and an airflow sensor. Radial micro-jets are used to break a coupling and act as an active closed-loop method. The control method used radial jets effectively to control the thermoacoustic instability and reduces sound pressure level to background level (100 dB to 44 dB) in short span of time (10 Second). • LabVIEW Interface for Arduino (LIFA), LabVIEW, and DAQ are very useful in developed closedloop active control method. • Developed closed loop active control method is very effective for suppression of thermoacoustic instability. • Developed closed loop active control method used air in the form micro jets to control thermoacoustic instabilities.