An aerosol is defined as an assembly of liquid or solid particles suspended in a gaseous medium. Aerosols are useful in a wide variety of applications. For example, it is often desirable to treat respiratory ailments with, or deliver drugs by means of, aerosol sprays of finely divided particles of liquid and/or solid, e.g., powder, medicaments, etc., which are inhaled into a patient's lungs. Aerosols are also used for purposes such as providing desired scents to rooms, applying scents on the skin, and delivering paint and lubricant. Aerosols have also been considered for fuel delivery systems for high performance engines and turbines where the small particle size influences ignition rates, combustion efficiencies and flame speed. Aerosol generation in areas of combustion initially result in the formation of vapor, but may after ignition result in smoke particles and vapor, due to the temperature experienced in the furnace.
Previously, combustion aerosols were generated for test purposes using actual vehicle exhaust transported through a long hose to test chambers. In some cases, small engines were located inside or outside a test chamber to generate the aerosols. There was very little control of the output when actual vehicles and engines were used. In addition, the particle size distribution and concentration changed during the transport of these aerosols through the long transport tube.