Thermoacoustic instabilities: Should the Rayleigh criterion be extended to include entropy changes?

Thermoacoustic instabilities: Should the Rayleigh criterion be extended to include entropy changes?

The Rayleigh criterion (which measures the correlation between pressure and heat release) is the standard tool used to investigate and predict combustion instabilities both in experimental and numerical studies. However, the Rayleigh term is just one of the terms appearing in the acoustic energy equation. The recent development of Large Eddy Simulations (LES) for combustion chambers allows to c...

Can Chemotherapy Be Extended to Include the Intracellular Disease Agents?

The present limits of successful chemotherapy do not quite coincide with the line of division between extracellular and intracellular disease agents. Thus chemotherapeutic benefit in experimental murine typhus has recently been reported by Moragues, Pinkerton, and Greiff (1944), and in human epidemic typhus by Yeomans and others (1944). Chemotherapeutic benefit is well authenticated for infecti...

Generalized Rayleigh criterion for non-axisymmetric centrifugal instabilities

Thermoacoustic Instabilities: Modelling and Control

The goal of this study was twofold. First, modelling strategies were proposed to characterize the dynamics driving the thermoacoustic instabilities in a swirl-stabilized premixed burner. Secondly, this model was used to synthesize controllers in order to apply active control strategies to suppress this phenomenon. An experimental combustor model based on acoustic properties of the combustion ch...

Modeling and Active Control of Thermoacoustic Instabilities

Due to stringent emission regulations, modern gas turbines work in lean premixed mode and thermoacoustic instabilities are often observed. They cause mechanical damage and therefore have to be reduced. This paper describes the development of an acoustic network model for a lab-scale lean premixed methane combustor at ETH Zurich. The model is verified against experimental data and is then used t...