Document Type : Research Article

Authors

1 Associate Professor . Department of Aerospace Engineering, Sharif University of Technology Tehran , Iran.

2 Ph.D. Student . Department of Aerospace Engineering, Sharif University of Technology, Tehran , Iran

3 M.Sc. Student. Department of Aerospace Engineering, Sharif University of Technology Tehran , Iran.

Abstract

Experimental and numerical analysis of a gas turbine model combustor is performed for two cases of regular operation, and attached flow (Coanda jet). The flame shape is visualized experimentally to reveal the differences in the flame structure of the two casesThe combustor sound frequency is measured experimentally and is close to the plenum's resonance frequency. Analysis of the measured resonance sound in frequency space reveals two fundamental frequencies for the normal operation and only one for the case of attached flow. After verifying the numerical results for the cold flow of the burner under normal operation, numerical modeling of both cases is performed using a large eddy simulation. Numerical results predict the attachment of the flow (in the form of a Coanda jet) to the dump plane of the burner for a change in a split ratio of flow between the inner and outer nozzles. In the case of flow attachment, it is shown that less negative axial velocities exist at the chamber entrance and outer nozzle instability ceases. In this way, the plenum acts as a normal single neck Helmholtz resonator with one fundamental frequency for resonance when flow adheres to the burner head. ‌‌

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Main Subjects

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