Acoustic investigation of perforated liners in gas turbine combustors

Shahjalal, Abdullah

Abstract

Modern combustion systems in industrial applications, from the gas turbine to aero or rocket engines, have become more critical during the last few years due to an exponential increase in commercial air traffic, resulting in an elevated level of atmospheric pollution in the form of exhaust smoke. To develop an efficient combustion system under variable load conditions, bias flow has been introduced progressively in the flame tube to decrease the temperature of the combustor liner in a consistent manner. Additionally, it is introduced as a passive damping device to increase the acoustic energy absorption from the system.
This thesis amalgamates gas turbine combustor liner acoustic and static pressure measurements, along with their predictions. The primary objective of this investigation is to identify the passive damper maximum acoustic energy absorption properties. It will also collect information for designers to develop a cylindrical combustor liner geometry, along with flow factor, thermodynamic property and acoustic factors. A series of experiments was conducted, and the outcome of the investigation was compared with prior research, simulated data, and predictions to validate how this examination can be fundamental in advancing modern combustion systems.
The results suggest that non-zero bias flow can greatly improve energy absorption and shift the peak frequency; the system operates as a Helmholtz resonator. Static pressure measurements suggest that as the mass flow rate changes, so too does pressure ratio, which creates a nonlinear absorption property of the combustor. The liner with the lowest porosity creates the pressure curve for double layer combustors. This could prove useful in assisting architects to utilize the combustor as a damper, metering liner or, indeed, a combination of both. A semi-empirical hybrid model is developed based on experimental data.

Citation

Shahjalal, A. (2021). Acoustic investigation of perforated liners in gas turbine combustors. (Thesis). University of Hull. Retrieved from https://hull-repository.worktribe.com/output/4223014

• Thesis Type: Thesis
• Deposit Date: Mar 26, 2021
• Publicly Available Date: Feb 23, 2023
• Keywords: Engineering
• Public URL: https://hull-repository.worktribe.com/output/4223014
• Additional Information: School of Engineering and Computer Science, The University of Hull
• Award Date: Jan 1, 2021