Performance of Canola Methyl Ester Biofuel in a Partial Swirl Spray Flame Combustor

The performance of canola methyl ester (CME) biofuel in a partial swirl spray flame combustor is compared to that of No. 2 diesel fuel in this paper. The spray flame was enclosed in an optically accessible combustor and operated at atmospheric pressure with a co-flow of heated air. Fuel was delivered through a swirl-type air-blast atomizer with an injector diameter of 300 microns. A two-component phase Doppler particle analyzer was used to measure the spray droplet size, axial and radial velocity distributions. Radial and axial concentration measurements of NO, CO, CO2 and O2 were made in the flame environment. Axial and radial flame temperature measurements were made using a Type R thermocouple. The volumetric flow rates of fuel, atomization air and co-flow air were kept constant for both fuels. The droplet SMD at the nozzle exit for CME biofuel are smaller than the No. 2 diesel fuel implying faster vaporization rates for the CME biofuel. Flame temperature decreases more rapidly for the CME biofuel than for the No. 2 diesel fuel in both axial and radial directions. CME biofuel produced lower in-flame NO and CO peak concentrations than No. 2 diesel fuel.

An Experimental Data Base for the Computational Fluid Dynamics of Combustors

A model axisymmetric gas-fired can combustor is used to (1) establish the sensitivity of the aerodynamic and thermal structure to inlet boundary conditions, and (2) thereby establish a demanding and comprehensive data base for the computational fluid dynamics of combustors. The parameters varied include fuel injection angle and inlet configuration. Detailed characterizations of the aerodynamic and thermal flowfields are accomplished using two-color laser anemometry and a Type R thermocouple, respectively. Specific results show that the reactor operation is especially sensitive to modest changes in both the inlet geometry and fuel injection angle. For example, the addition of a step expansion significantly alters the size and location of the swirl-induced toroidal recirculation zone. Further, the use of the step expansion, in combination with the injection of fuel matched to the swirl aerodynamics, transforms the recirculation zone to an on-axis structure. The addition of a divergent inlet further enhances the effectiveness of the backmixing by enlarging the recirculation zone. The data base developed for these conditions is carefully documented and provides a comprehensive challenge for the computational fluid dynamics of combustors.