Accession Number : ADP007953

Title :   Experimental Investigations on the Transition from Stable to Unstable Combustion by Means of Active Instability Control,

Corporate Author : TECHNISCHE UNIV MUNICH (GERMANY F R)

Personal Author(s) : Gleis, S. ; Vortmeyer, D. ; Rau, W.

Report Date : DEC 1990

Pagination or Media Count : 7

Abstract : The interaction of numerous parameters affect excitation and development of combustion instabilities, and determine the excited acoustic modes. Therefore, to avoid combustion instabilities, it is essential to make out the sources of disturbances and to interrupt the feed back loop. The newly developed method of Active Instability Control' (AIC) opens experimental opportunities for this kind of diagnostics, because after having stabilized the oscillating system it starts to oscillate again if the AIC-system is switched off. It takes about 300 msec until the oscillation is again fully developed. During this transition period we are able to register the combustion chamber pressure, the intensity of chemical reaction and the flame contours time resolved by high-speed/-schlieren-cinematography. Experiments with a laboratory combustor showed, that during the onset of instability various mechanisms of excitation can be observed. Further investigations pointed out that although vortex shedding is an important driving force for oscillations, it is not the origin for instability.

Descriptors :   *INSTABILITY, *COMBUSTION STABILITY, *TRANSITIONS, ACOUSTICS, CHAMBERS, CHEMICAL REACTIONS, CHEMICALS, CINEMATOGRAPHY, COMBUSTION, COMBUSTION CHAMBERS, COMBUSTORS, CONTOURS, EXCITATION, FLAMES, INTENSITY, INTERACTIONS, LABORATORIES, LOOPS, OSCILLATION, PARAMETERS, PRESSURE, TIME, TRANSITIONS, VELOCITY, VORTEX SHEDDING.

Subject Categories : Combustion and Ignition

Distribution Statement : APPROVED FOR PUBLIC RELEASE