Experimental device and method for researching thermo-acoustic instability longitudinal and tangential mode coupling mechanism

Abstract

The invention relates to an experimental device and method for researching a thermo-acoustic instability longitudinal and tangential modal coupling mechanism. The experimental device and method are used for researching thermo-acoustic instability modal coupling phenomena of combustion systems such as aerospace engines and ground gas turbines. The device is mainly an electric heating single-heat-source cross-shaped combustion chamber with a variable combustion chamber structure size, longitudinal and tangential mode coupling thermo-acoustic instability which simultaneously exists in a real engine is simulated, and heat source power and flow velocity control is facilitated. The longitudinal and tangential lengths of the combustion chamber may be achieved by modularly increasing or decreasing the number of tube segments and changing the position of the piston within the tangential tube, thereby achieving thermo-acoustic instability of longitudinal and tangential modal coupling at different resonant frequencies. Herein, quick response thermocouple and a pressure sensor are used in an experiment to obtain temperature data and sound pressure signals. By combining analysis methods such as power spectral density calculation, signal filtering, short-time Fourier transform and signal reconstruction, the characteristics and mechanism of thermo-acoustic unstable longitudinal and tangential mode coupling under different combustion chamber structures and sizes, different heat source powers and different air average flow rates can be researched. The experimental device is low in cost and simple in structure, and facilitates understanding and utilization of the thermo-acoustic unstable mode coupling phenomenon.

Description

technical field [0001] The invention relates to a novel experimental method of thermoacoustic unstable longitudinal and tangential mode coupling mechanism, which is mainly used for the research of thermoacoustic unstable mode coupling phenomenon occurring in various engine combustion chambers or combustion devices in other fields. Background technique [0002] In aerospace engines, especially lean premixed engines, there is a problem of detrimental thermoacoustic instabilities. Thermoacoustic instability is generated by the coupling of unsteady heat release and acoustic disturbance, which can easily cause thrust oscillation, mechanical vibration and excessive thermal load, which will affect the operability and reliability of the combustion system, and eventually cause the system to fail. In modern gas turbines, an annular combustor is often used in order to provide an axially shorter combustor and a more uniform temperature distribution at the turbine inlet. In many cases, ...

AI Technical Summary

Problems solved by technology

However, due to the complex structure and high cost of this experimental device, the size cannot be changed after the device is manufactured, so it is difficult to use in the research of multiple structural parameters and multiple working conditions, so it is difficult to reveal various complex longitudinal and tangential aspects of the annular combustion chamber. modal coupling mechanism, so an experimental device with simple structure, low price and easy to change structural parameters is needed

Images