The Design Process for a Closed Combustion Chamber Flow Blurring Nozzle

Abstract

©, Copyright Association of Energy Engineers (AEE). This research outlines a process whereby a flow blurring nozzle is optimized for use in a meso-scale combustion chamber. Flow blurring is defined as the generation of small turbulence scales in a liquid from a singular back-flow pattern of a gas. Flow blurring nozzles are beginning to be adapted in many technical applications, from emission spectrometry of heavy metals in biodiesel, vaporization of high viscosity fuels to meso-scale combustion applications. This nozzle can vaporize liquids at low flow rates efficiently and inexpensively. It uses an air stream to break up the liquid but it operates in a novel flow blurring regime differentiating it from a regular air blast atomizer. There are two issues with using this nozzle for combustion applications. The first is that the air used to vaporize the hydrocarbon in the flow blurring nozzle is insufficient to burn all the hydrocarbon and it is difficult to increase this air supply. The second issue is that the vaporized mixture at the exit of the flow blurring nozzle has a relatively high velocity. The mixture velocity must be decelerated to enable stable combustion without blowoff. This article outlines the design process for solving both these issues. In total, five design iterations were implemented before a satisfactory final design was achieved.