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1 September 2002

NASA advances flowmeter, Ethernet technologies

By Jim Strothman

NASA's John F. Kennedy Space Center (KSC) has developed two technologies—a quality flowmeter and an Ethernet-based data acquisition system—that NASA is convinced have potential commercial uses.

KSC's flowmeter indicates the quality of liquid nitrogen test systems. Using two quality flowmeters connected in series, researchers are also determining the technology's ability to accurately measure humidity and velocity.

NASA said its Ethernet-based data acquisition technology, also developed at KSC, offers high-performance, Ethernet-based data acquisition at a relatively low cost. NASA predicts that a novel architecture, which combines KSC's signal conditioning amplifier recorder (SCAMPR) with high speed, large bandwidth, and high accuracy, will significantly expand the market for conventional commercial data acquisition systems.

The space agency hopes to license both technologies to businesses interested in developing commercial applications.

The basis of the technology comes from measuring the dielectric constant variation between the phases of a two-phase mixture. As the ratio of the two phases changes, the overall capacitance changes.

Potential quality flowmeter commercial uses, KSC said, include the following:

• Steam plants, where maintenance of high-quality vapor is important.
• Food processing, where the maximum velocity of a solid/water mixture is required to determine optimum sterilization times.
• Level indicator for use in modular cryogenic tanks. The fill level or overfill condition can be monitored electronically with this meter.
• Humidity indicator for heat/ventilation/air conditioning in commercial processes, where humidity control is very important.

According to NASA, the flowmeter's benefits include a significantly higher dynamic range and quicker response than existing capacitance sensors, as well as good sensitivity. This higher dynamic range makes it possible to use one meter for several purposes, such as humidity indication, prior to phase measurement of cryogenic flows.

Accurate measurements can be made by taking two measurements in series on a flowing, two-phase mixture using cross correlation of the two readings. The system also measures the temperature and pressure of a mixture. With those parameters, you can calculate density.

The quality flowmeter system consists of an insulated pipe section with an inner solid probe held in place by insulating standoffs. The probe is electrically isolated from the inside of the pipe. The probe has a wire attached to each end, with the wires electrically isolated from each other.

The wires pass through the pipe wall to a connector. An innovative capacitance-measuring circuit measures capacitance with very high sensitivity. Two circuits can measure the average capacitance of the mixture around each end of the probe. A PC calculates the velocity and flow rate of the moving two-phase mixture stores and analyzes the readings.

KSC said the meter has an increase in inner diameter around the probe to keep the flow cross section constant and has a vacuum jacket to minimize heat losses. Its original intent was for use in cryogenic flows such as liquid nitrogen, oxygen, and hydrogen.

Ethernet-based data acquisition

KSC said potential commercial uses include engine test stands, crash test facilities, rocket launch facilities and test stands, and wind tunnels.

Costs are low, NASA said, because it uses commercial, off-the-shelf hardware on a single board and communicates via a standard Ethernet connection to any PC. Other features include the following:

• Scalable and configurable architecture that supports a broad range of memory, data rates, and other specifications
• Internal data storage for fast data bursts without requiring large-bandwidth data links
• Automatic system health checks and continuous self-calibration, plus a distributed approach including independent data storage for each amplifier channel, reducing the risk of data loss
• Instructions that can be downloaded dynamically for reconfiguration and future execution
• Ability to maintain functionality of prior systems while reducing cost and increasing reliability

KSC said it developed the SCAMPR to fill the need for a high-end, low-cost data acquisition system. Because the recording function is located at the data acquisition site, large-bandwidth communications links are not required.

The technology communicates and interfaces via standard TCP/IP to any PC. In addition, instructions can download dynamically to the SCAMPR to customize any application. Now in the early prototype stage, the technology will ultimately replace KSC's existing data acquisition system for launches and tests, NASA said.

Parties interested in licensing a NASA invention may contact Lynne R. Henkiel, KSC industry liaison, KSC Technology Commercialization Office Mail Code YA-C1, Kennedy Space Center, FL 32899; (321) 867-8130; fax: (321) 867-2050. IT