Flow simulations of an axisymmetric two-dimensional 3rd generation DLE burner
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
In this thesis a parameter study of a gas turbine burner used in the Siemens Gas Turbine SGT-800 and SGT-700 has been performed using computational fluid dynamics. The parameter study was aimed at determining the stability range of the flow field inside the burner and combustion chamber. To perform the study a simplified two dimensional model of the actual burner was developed. The software used for the simulations was Ansys CFX (versions 11.0 and 12.0) and the parameter that has been studied is the swirl number which can be described as a relation between the angular and axial momentum. To change the swirl number scale factors were introduced at the inlet allowing for the velocity profiles to vary. The results showed that the stability range where the flame inside the combustion chamber took the shape of a cone in between the limits of flameback or a rotating jet flame was narrower than assumed from the start. Also the influence of including combustion in the model showed similar results but an even narrower stability range. Besides the parameter study a model has been developed to account for the three dimensional swirling caused by the swirl cone, where forces were applied to force the flow to behave in a certain way. Even though the flow can be mimicked with this approach the fuel distribution in the burner is suffering from some absent three dimensional effect which causes the fuel distribution to be more uniform as compared to simulations made with the axisymmetric model. To validate the simulations the water rig located at Siemens was used where the goal was to examine the radial fuel distribution in five burners. This was done by recording movies of a laser sheet that illuminated water mixed with fluorescence representing fuel. These movies could then be evaluated using MATLAB and comparison to simulations again highlighted the inaccuracy of the fuel distribution in the two-dimensional axisymmetric model. One of the major conclusions of the thesis was that the developed two dimensional axisymmetric model is a valid instrument when performing parameter studies and it is recommended for future studies. When trying to account for the mixing effect of the swirl cone some three dimensional effect is lost and in order to be able to use the complete model of the whole burner this issue has to be resolved.
Place, publisher, year, edition, pages
2011. , 81 p.
Technology, CFD, Gas Turbines, Combustion
IdentifiersURN: urn:nbn:se:ltu:diva-49904Local ID: 7371dab3-0e6d-406d-bd6f-46d522041fe1OAI: oai:DiVA.org:ltu-49904DiVA: diva2:1023252
Subject / course
Student thesis, at least 30 credits
Space Engineering, master's level
Validerat; 20101222 (anonymous)2016-10-042016-10-04Bibliographically approved