Abstract
The present paper compares the flow structure and flame dynamics during combustion of methane and syngas in a model gas-turbine swirl burner. The burner is based on a design by Turbomeca. The fuel is supplied through injection holes between the swirler blades to provide well-premixed combustion, or fed as a central jet from the swirler’s centerbody to increase flame stability via a pilot flame. The measurements of flow structure and flame front are performed by using the stereo particle image velocimetry and OH planar laser-induced fluorescence methods. The measurements are performed for the atmospheric pressure without preheating and for 2 atm with the air preheated up to 500 K. The flow Reynolds numbers for the non-reacting flows at these two conditions are 1.5 × 103 and 1.0 × 103, respectively. The flame dynamics are analyzed based on a high-speed OH* chemiluminescence imaging. It is found that the flame dynamics at elevated conditions are related with frequent events of flame lift-off and global extinction, followed by re-ignition. The analysis of flow structure via the proper orthogonal decomposition reveals the presence of two different types of coherent flow fluctuations, namely, longitudinal and transverse instability modes. The same procedure is applied to the chemiluminescence images for visualization of bulk movement of the flame front and similar spatial structures are observed. Thus, the longitudinal and transverse instability modes are found in all cases, but for the syngas at the elevated pressure and temperature the longitudinal mode is related to strong thermoacoustic fluctuations. Therefore, the present study demonstrates that a lean syngas flame can become unstable at elevated pressure and temperature conditions due to a greater flame propagation speed, which results in periodic events of flame flash-back, extinction and re-ignition. The reported data is also useful for the validation of numerical simulation codes for syngas flames.
Highlights
The efficient combustion of synthesis gas or ‘syngas’ in gas turbines is becoming more relevant due to the development of integrated gasification combined cycle (IGCC) power plants, where the products of coal gasification are burned in gas turbines [1]
Syngas can be obtained from biomass and even some types of waste [2]
The combustion chamber is equipped with observation windows, which are made of fused silica and provide flame observation and optical diagnostics for the pressure up to 8 atm
Summary
The efficient combustion of synthesis gas or ‘syngas’ in gas turbines is becoming more relevant due to the development of integrated gasification combined cycle (IGCC) power plants, where the products of coal gasification are burned in gas turbines [1]. Syngas can be obtained from biomass and even some types of waste [2]. The studies of syngas combustion at elevated pressure and temperature conditions are important. Modern low-emission gas turbine combustors are based on a lean premixed combustion technology [3]. The optimization of the flow aerodynamics allows organizing efficient fuel combustion with low concentrations of both CO and NOx in combustion products
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
