The effect of fluid properties on the atomisation of sprays using flat fannozzles

A total of 350 different droplet spectra were sampled using a phase Doppler droplet sizing laser technique. Pressure and fluid properties (viscosity a nd surface tension) were varied to measure their effect on droplet spectra for flat fan nozzles. Viscosity was altered by using various concentrations of glycerol up to 60 %. Agral 90, a nonionic surfactant, was used to vary surface tension. Dynamic surface tension was measured using the maximum bub ble pressure method. Agral concentration higher than 0,2 % was also shown t o effect viscosity. This relationship made it difficult to disassociate the effects of viscosity and surface tension. The effect of pressure was unive rsal and irrespective of other factors. It proved the easiest and best way to control the volume of droplets prone to drift. Viscosity effects were mo re prominent at low pressures. Increased viscosity did not reduce the volum e of small droplets. Surface tension of fluid had also effects on droplet s pectra. Increased Agral concentration decreased dynamic surface tension, co nsequently decreasing droplet size and volume median diameter.