CHALLENGES FOR FUTURE RESEARCH IN ATOMIZATION AND SPRAY TECHNOLOGY: ARTHUR LEFEBVRE MEMORIAL LECTURE

Abstract

The current state-of-the-art of atomizer design, aircraft engines, diesel and gasoline engines, medical sprays, spray painting of automobiles, and laser optical instruments is reviewed. Future research for several decades will be driven by increasingly urgent demands to improve fuel and energy efficiency, and to drastically reduce the emission of pollutants. A much greater degree of control is required, not only in spray systems, but for pressure and flow rates which are introduced into atomizers. An improved understanding and control of liquid and air flows inside atomizers will be necessary. The breakup of liquid jets and sheets in many current spray systems results in chaotic generation of drop sizes and velocities. Electrosprays and ultrasonic sprays provide the means to generate more steady and controlled sprays. Major breakthroughs in the physics of diesel injector sprays have been achieved by using high intensity x-rays from the Synchroton at Argonne Labs. Moving away from single injectors to multiple injectors and replacing drilling of holes with etching and lamination allows multiple nozzles, with air and liquid swirl passages, to generate micro-sized droplets, fully dispersed in combustion chambers. The Federal Drug Administration has authorized the inhalation of insulin for treatment of diabetes. Aerosol particle sizers must be in the range of one to four microns. Stents, for the support of collapsed arteries, must be spray-coated with medication. Cryogenic sprays are used for cooling the skin during dermatological skin surgery. These are examples of important developments in the field of medicine. Future collaboration between physicists, mechanical, chemical and materials engineers, mathematicians, computationalists and experimentalists, with industrial designers and engineers, will offer many opportunities for young engineers to establish careers in atomization and spray technology.