The Design Process for a Closed Combustion Chamber Flow Blurring Nozzle

Abstract

This research outlines a process whereby a flow blurring nozzle isoptimized for use in a meso-scale combustion chamber. Flow blurringis defined as the generation of small turbulence scales in a liquid from asingular back-flow pattern of a gas. Flow blurring nozzles are beginningto be adapted in many technical applications, from emission spectrom-etry of heavy metals in biodiesel, vaporization of high viscosity fuels tomeso-scale combustion applications. This nozzle can vaporize liquidsat low flow rates efficiently and inexpensively. It uses an air stream tobreak up the liquid but it operates in a novel flow blurring regime dif -ferentiating it from a regular air blast atomizer. There are two issues withusing this nozzle for combustion applications. The first is that the airused to vaporize the hydrocarbon in the flow blurring nozzle is insuf -ficient to burn all the hydrocarbon and it is difficult to increase this airsupply. The second issue is that the vaporized mixture at the exit of theflow blurring nozzle has a relatively high velocity. The mixture velocitymust be decelerated to enable stable combustion without blowoff. Thisarticle outlines the design process for solving both these issues. In total,five design iterations were implemented before a satisfactory final de -sign was achieved.