BRIEF COMMUNICATION Control of Longitudinal Oscillations in a Constant Area Combustor: Numerical Simulation
نویسندگان
چکیده
The phenomenon of combustion driven oscillations has long held the interest of scientists and engineers. According to the so-called Rayleigh criterion [1], driving of the pressure oscillations occurs if the periodic heat release rate is generally coincident with the pressure oscillations. The main mechanisms involved are considered to be both thermoacoustic and vortical in nature [2-5]. Useful insight into the fundamental cause of combustion instability can be gained by considering the generalized Rayleigh criterion as advanced by Chu [6]. Due to the inherent complexity of the physical phenomena involved in combustion instability, research in this field has relied heavily on experimental observations [3-5, 7, 8], simplified linear analysis [9], or, more recently, largeeddy simulation [10]. Shyy and Udaykumar [11] have developed a one-dimensional nonlinear model to simulate the flow and heat release in a constant area combustor. The heat release model used there has been extended from experimental observations of Langhorne [12] and is a modified version of the model advanced by Bloxidge et al. [9]. The model developed in Ref. [9] follows from a onedimensional linear stability analysis for acoustic waves in ducts, relating the fluctuations of heat release rate at the gutter to the velocity fluctuations through an empirical factor determined from experiments. The heat fluctuation is then assumed to travel downstream at the average gutter velocity and thus the fluctuations at any downstream location specified. In the present model, instead of specifying the unsteady heat release at every point in time and space, the heat release rate at
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