Drop-Size Studies in a Radially-Uniform Fuel Spray

A specially-designed grid of “microscopic” plain-jet airblast atomizers is used to produce a uniform distribution of fuel drops across a flowing air stream. The atomizer array comprises 68 evenly-spaced, individual airblast atomizers, each of which consists of two concentric tubes (diameters 0.81 and 2.74 mm) with fuel and air being supplied to the inner and outer tubes respectively. Atomizing air and fuel flow rates are adjusted separately to produce a wide variety of drop sizes that cover the range of most practical interest. The atomizer array is located within a 15 cm diameter combustor which is supplied with air at pressures up to 1520 kPa, and velocities from 5 to 20 m/s. The main spray characteristics of mean drop size and drop size and drop-size distribution are measured using a Malvern particle analyzer. Results are presented to show the effects of variations in air and fuel properties on the spray characteristics of this novel form of fuel injector.