Date of Award

Spring 2015

Degree Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

First Advisor

Robert Lucht

Committee Chair

Robert Lucht

Committee Member 1

Hukam Mongia

Committee Member 2

Sameer Naik

Abstract

Over the past few decades, there has been a significant increase in greenhouse gases such as CO2, N2O, and CH4 produced from gas turbine engines. Keeping this in mind, current research work is being carried out for reducing NOx produced from combustors. The objective of this research is to determine the feasibility of Distributed Combustion Systems (DCS) for increasing efficiency and reducing NOx emissions. ^ A DCS has a main combustion zone (MCZ) where 90% of the fuel is burned and is followed by a secondary combustion zone (SCZ) in which jets carrying fuel are injected into the vitiated crossflow from the MCZ. This fuel jet auto-ignites under the influence of the high temperature vitiated crossflow. A new type of accelerating distributed combustion system has been designed in this project. In the current design, higher Mach numbers of the main flow can be obtained at the jet exit after reducing the exit area of secondary combustion zone by about five times compared to the inlet. Along with the design, a detailed one-dimensional heat transfer analysis has been performed. A Matlab code was used to determine whether final temperatures of the thermal barrier coating (TBC) and cooling water fall within acceptable design constraints. Conduction, convection, and radiation at steady state were used for determining heat transfer relationships between different materials. Water and nitrogen flow rates as well as the dimensions of cooling water channels were varied parametrically to find ideal conditions. Based on the heat transfer calculations, 8.5 gpm water are needed to cool the secondary combustion zone to maintain temperature within material property limits. ^ Various laser-based measurement techniques such as Planar Laser-Induced Flourescence (PLIF), Particle Image Velocimetry (PIV), and Coherent Anti-Stokes Raman Spectroscopy (CARS) will be performed to study the combustion in the accelerating flow channel. Emissions sampling will be performed downstream of combustion zone using a water-cooled sampling probe. These measurements will provide insight into the various physical phenomena associated with NOx production.

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