Development of gas turbine combustor preliminary design methodologies and preliminary assessments of advanced low emission combustor concepts

摘要

It is widely accepted that climate change is a very serious environmentalconcern. Levels of carbon dioxide (CO2) and other emissions in the globalatmosphere have increased substantially since the industrial revolution and nowincreasing faster than ever before. There is a thought that this has already ledto dangerous warming in the Earth’s atmosphere and relevant changes around.Emissions legislations are going to be stringent as the years will pass. Hydrocarbon fuel cost is also increasing substantially; more over this is non-renewable source of energy.There is an urgent need for novel combustor technologies for reducing emissionas well as exploring alternative renewable fuels without effecting combustorperformance. Development of novel combustors needs comprehensiveunderstanding of conventional combustors. The design and development of gasturbine combustors is a crucial but uncertain part of an engine developmentprocess. At present, the design process relies upon a wealth of experimentaldata and correlations. Some major engine manufacturers have addressed theabove problem by developing computer programs based on tests and empiricaldata to assist combustor designers, but such programs are proprietary. There isa need of developing design methodologies for combustors which would lead tosubstantial contribution to knowledge in field of combustors. Developed designmethodologies would be useful for researchers for preliminary designassessments of a gas turbine combustor.In this study, step by step design methodologies of dual annular radial and axialcombustor, triple annular combustor and reverse flow combustor have beendeveloped. Design methodologies developed could be used to carry outpreliminary design along with performance analysis for conventional combustionchambers. In this study the author has also proposed and undertakenpreliminary studies of some novel combustor concepts.A novel concept of a dilution zone less combustor has been proposed in thisstudy. According to this concept dilution air would be introduced through nozzleguide vanes to provide an optimum temperature traverse for turbine blades.Preliminary study on novel dilution zone less combustor predicts that the lengthof this combustor would be shorter compared to conventional case, resulting inreduced weight, fuel burn and vibrations. Reduced fuel burn eventually leads tolower emissions.Another novel concept of combustor with hydrogen synthesis from kerosenereformation has been proposed and a preliminary studies has been undertakenin this work. Addition of hydrogen as an additive in gas turbine combustorshows large benefits to the performance of gas turbine engines in addition toreduction in NOx levels. The novel combustor would have two stages,combustion of ~5% of the hydrocarbon fuel would occur in the first stage athigher equivalence ratios in the presence of a catalyst, which would eventuallylead to the formation of hydrogen rich flue gases. In the subsequent stage thehydrogen rich flue gases from the first stage would act as an additive tocombustion of the hydrocarbon fuel. It has been preliminary estimated that themixture of the hydrocarbon fuel and air could subsequently be burned at muchlower equivalence ratios than conventional cases, giving better temperatureprofiles, flame stability limits and lower NOx emissions.The effect of different geometrical parameters on the performance of vortexcontrolled hybrid diffuser has also been studied. It has been predicted thatvortex chamber in vortex controlled hybrid diffuser does not play any role inaltering the performance of diffuser.The overall contribution to knowledge of this study is development of combustorpreliminary design methodologies with different variants. The other contributionto knowledge is related to novel combustors with a capability to produce lowemissions. Study on novel combustor and diffuser has yielded application of twopatent applications with several other publications which has resulted in acontribution to knowledge. A list of research articles, two patents, awards andachievements are presented in Appendix C.