Combustion System Damping Augmentation With Helmholtz Resonators

Abstract

This paper describes an analytical and experimental investigation to enhance combustion system operability using side branch resonators. First, a simplified model of the combustion system dynamics is developed in which the large amplitude pressure oscillations encountered at the operability limit are viewed as limit cycle oscillations of an initially linear instability. Under this assumption, increasing the damping of the small amplitude combustion system dynamics will increase combustor operability. The model is then modified to include side branch resonators. The parameters describing the side branch resonators and their coupling to the combustion system are identified, and their influence on system stability is examined. The parameters of the side branch resonator are optimized to maximize damping augmentation and frequency robustness. Secondly, the model parameters for the combustor and side branch resonator dynamics are identified from experimental data. The analytical model predicts the observed trends in combustor operability as a function of the resonator parameters and is shown to be a useful guide in developing resonators to improve the operability of combustion systems.

Dynamics and stability of lean-premixed swirl-stabilized combustion

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Transmission Loss Analysis of a Parallel-Coupled Helmholtz Resonator Network with a Green's Function Approach

“…If the membrane is assumed to be a rigid piston, y is a function of time only, then Eq. (6) can be simplified to ∂V ′ 1 (t)/∂t = πa 2 y(t), as modeled by Griffin et al [15]. However, to accurately predict the response of coupled resonator network, the structural-acoustic coupling including higher-order membrane vibration modes needs to be captured.…”

Feedback Control of Combustion Instabilities Using a Helmholtz Resonator with an Oscillating Volume

“…They are unlikely to make the systems more unstable, but tend to be effective for only a narrow frequency range and unable to respond to changes in operating conditions. Helmholtz resonators with fixed cavity volume are widely used as acoustic dampers in gas turbine combustion systems (Bellucci et al, 2004;Dupere and Dowling, 2005;Gysling et al, 2000). Their damping mechanism is primarily due to thermo-viscous and vortex shedding losses (Dupere and Dowling, 2005;Kinsler et al, 2000).…”