Combustion instability

Combustion instabilities are physical phenomena occurring in a reacting flow (e.g., a flame) in which some perturbations, even very small ones, grow and then become large enough to alter the features of the flow in some particular way.^[1][2][3]

In many practical cases, the appearance of combustion instabilities is undesirable. For instance, thermoacoustic instabilities are a major hazard to gas turbines and rocket engines.^[1] Moreover, flame blowoff of an aero-gas-turbine engine in mid-flight is clearly dangerous (see flameout).

Because of these hazards, the engineering design process of engines involves the determination of a stability map (see figure). This process identifies a combustion-instability region and attempts to either eliminate this region or moved the operating region away from it. This is a very costly iterative process. For example, the numerous tests required to develop rocket engines ^[4] are largely in part due to the need to eliminate or reduce the impact of thermoacoustic combustion instabilities.