NASA Taps Supersonics for New Cleaning System
By LISA A. KARTER
John F. Kennedy Space Center, FL–NASA engineers have developed a new supersonic cleaning system that does not damage surfaces and may soon be used to remove contaminants from space shuttle hardware and other sensitive structures.
Dubbed the Supersonic Gas-Liquid Cleaning System, it works by mixing air and water from separate pressurized tanks and ejecting the mixture at supersonic speeds from a series of nozzles at the end of a hand-held wand. At these speeds, the water droplets have the kinetic energy to forcibly remove the contaminant material.
The cleaning system was developed as an alternative to chlorofluorocarbon-based solvents (CFC). Says NASA Lead Project Engineer Raoul Caimi: “During our testing programs, we found that the gas-liquid supersonic system actually does a better job of cleaning than a system that uses CFCs.”
NASA and two independent companies, Precision Fabricating and Cleaning Co. (Cocoa, FL) and Va-tran Systems, Inc. (Chula Vista, CA), have developed separate patent license agreements for the technology to be used in commercial applications. These agreements are part of a technology transfer program between NASA and commercial companies, which can derive innovative commercial use from NASA-developed technology.
Va-tran Systems` Director of Engineering Jeffrey Sloan says the system will add a new technology to the company`s current precision cleaning capabilities.
The Supersonic Gas-Liquid Cleaning System consists of a high-pressure gas source, a regulator, supply lines, a throttling/tank pressurization gas orifice, shut-off and drain/replenish valves, a liquid injection orifice, and a wand fitted with a supersonic nozzle. The regulator supplies ~320-psig gas to the liquid tank and to the gas orifice from the high-pressure gas source. The gas pressure is further dropped to ~300 psig as it flows through the inline throttling/tank pressurization gas orifice. The liquid is pressurized by the pressure drop caused by the inline gas orifice. The liquid is then injected into the gas supply line upstream of the nozzle through a liquid-metering orifice just downstream of the gas orifice. In addition, the gas orifice sets the mixing ratio (liquid to gas) in combination with the liquid orifice. The mixture flows through the supply lines to the wand-mounted nozzle. The converging-diverging nozzle accelerates the gas-liquid mixture to supersonic velocities at the exit. The nozzle also sets the maximum gas flow rate since choked conditions exist at its throat.
Bill Sheehan, chief of Kennedy`s Technology Programs and Commercialization Office, says: “This is an innovative system that is recognized by industry to have many potential uses in the commercial market.” n
Editor`s Note: If you would like more information on the new cleaning system or are interested in licensing this NASA technology, please contact the Technology Programs and Commercialization Office, DE-TPO, Kennedy Space Center, FL 32899 or call (407) 867-3017.