Patternation

Sprays have a number of uses. In its natural form, we come across sprays in waterfall mists, rains and ocean sprays, according to Arthur Lefebvre, in his book, Atomization and Sprays. Within the household sphere, we use sprays in showers, garden hoses, spray paint cans, hair spray, deodorant sprays and more. Industrial uses of sprays include spray drying, coating, washing, and irrigating. Sprays are also used in many internal combustion engines to directly disperse the fuel into the combustion chamber and mix it with air so that either spontaneously ignite under high pressure and temperatures or they can be ignited using spark plugs. Patternation of sprays is important in a variety of applications including IC engines, turbines, spray coating, spray drying, agriculture, and consumer products. For example, asymmetries in patternation directly affect surface finish quality during painting and poor product quality during spray drying.Similarly, in gas turbines, variation in the spray pattern leads to fuel lean and fuel rich pockets resulting in excessive turbine wear and increased particulate emission. For metered-dose inhalers, the pattern of the spray is very important to ensure that the maximum amount of the drug goes through the throat passageways into the lungs.In agricultural nozzles the pattern of the spray is important so as to optimize the delivery of pesticides and fertilizers to the plants. Spray drying requires that the droplet sizes be closely controlled. In general, increasing the total drop surface area within the dryer will lead to higher evaporation rates and greater efficiency for the process.Similarly, pharmaceutical tablets owe their thin film surface coating to an atomizer produced spray that needs to be perfect. The coating not only masks taste but also performs key functions such as sealing the tablet from moisture to improve shelf life, controlling drug release rates to get slow and extended release tablets. Spray patterns are studied using diagnostic tools known as patternators. A patternator quantifies the spatial location of the drops emitted from a sprayer and visualizes the patterns of sprays. There are different types of patternators, mechanical and optical.