Date of Award

2012-01-01

Degree Name

Doctor of Philosophy

Department

Environmental Science and Engineering

Advisor(s)

ahsan choudhuri

Abstract

Development of a next generation gas turbine combustors for power production by using fossil fuels is increasing substantially in order to maintain energy sustainability. National Energy Technology Laboratory has made efforts for developing hydrogen and oxy-fuel based gas turbine combustors which could enhance plant efficiency and ensure low or zero NOx production without sacrificing operational advantages. The current experimental work aims to characterize the turbulent flow-field of premixed syngas/air flames, methane/oxy flames and syngas/oxy flames in a laboratory scaled burner by varying the Reynolds numbers, blockage ratios, firing inputs and blockage ratios in the upstream of the burner. The effects of turbulence, firing input and operating conditions on the position, local flow-field dynamics of the flame front, laminar burning velocity and turbulent burning velocities are investigated in the present study. A recent progress in high speed particle image velocimetry enables to capture the turbulent flow field with high resolution which results in better understanding of phenomena like vortex shredding at the burner exit. An experimental setup is designed to visualize the turbulent flow field of both CO-H2/air, CH4/O2/CO2 and CO-H2/O2/CO2 mixtures by varying the above parameters using high speed particle image velocimetry. The burner used in the current study is a tubular burner (19mm in diameter) with a turbulence creator positioned at a distance of 15 mm downstream from top of the burner. The blockage ratio's that is considered for the current set of experimental study are 73%, 83% and 92% respectively. The turbulence flow field of CO-H2/air, CH4/O2/CO2 and CO-H2/O2/CO2 combustion was recorded at different locations from the burner exit using Particle Image Velocimetry (PIV) technique.

For CO-H2/air flames at constant equivalence ratio of 0.9 and RE of 2000 the turbulent burning velocities not only increased with increase in hydrogen content but also increased when the BR's increased .Turbulent burning velocities increased with increase in BR's as the hydrogen content increased in syngas mixture at a constant laminar burning velocity for syngas compositions varying from 10%H2 to 30 % H2. Turbulent burning velocities increased with increase in the BR's along with the increase in N2 and CO2 in Syngas mixtures.CO2 as diluents is more prominent than N2, the increase of CO2 in the Syngas mixtures decrease the turbulent burning velocity.

For CH4/O2/CO2 flames at constant equivalence ratio of 1 and RE of 2500, the local velocity fluctuations not only increases with increase in BR's but also increased with increase in the firing inputs. At higher recirculation ratios of CO2, there has been a significant reduction in the flame temperature thereby resulting in reduce in effective flame area.

Language

en

Provenance

Received from ProQuest

File Size

119 pages

File Format

application/pdf

Rights Holder

Vishwanath Reddy Ardha

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