NASA Lewis Research Center's Icing Research Tunnel (IRT) is the
world's largest refrigerated wind tunnel and one of only three
icing wind tunnel facilities in the United States. The IRT was
constructed in the 1940's and has been operated continually since
it was built. In this facility, natural icing conditions are duplicated
to test the effects of in-flight icing on actual aircraft components
as well as on models of airplanes and helicopters. IRT tests have
been used successfully to reduce flight test hours for the certification
of ice-detection instrumentation and ice protection systems. To
ensure that the IRT will remain the world's premier icing facility
well into the next century, Lewis is making some renovations and
is planning others. These improvements include modernizing the
control room, replacing the fan blades with new ones to increase
the test section maximum velocity to 430 mph, installing new spray
bars to increase the size and uniformity of the artificial icing
cloud, and replacing the facility heat exchanger.
Most of the improvements will have a first-order effect on the IRT's airflow quality. To help us understand these effects and evaluate potential improvements to the flow characteristics of the IRT, we built a modular 1/10th-scale aerodynamic model of the facility. This closed-loop scale-model pilot tunnel was fabricated onsite in the various shops of Lewis' Fabrication Support Division. The tunnel's rectangular sections are composed of acrylic walls supported by an aluminum angle framework. Its turning vanes are made of tubing machined to the contour of the IRT turning vanes. The fan leg of the tunnel, which transitions from rectangular to circular and back to rectangular cross sections, is fabricated of fiberglass sections. The contraction section of the tunnel is constructed from sheet aluminum. A 12-bladed aluminum fan is coupled to a turbine powered by high-pressure air capable of driving the maximum test section velocity to 550 ft/sec (Mach 0.45). The air turbine and instrumentation are housed inside a fiberglass nacelle. Total and static pressure measurements can be taken around the loop, and velocity and flow angularity measurements can be taken with hot-wire and five-hole probes at specific locations.
The Scale Model Icing Research Tunnel (SMIRT) is undergoing checkout
tests to determine how its airflow characteristics compare with
the IRT. Near-term uses for this scale-model tunnel include determining
the aerodynamic effects of replacing the 52-year-old W-shaped
heat exchanger with a flat-faced heat exchanger. SMIRT is an integral
part of the improvements planned for the IRT because testing the
proposed IRT improvements in a scale-model tunnel will lower costs
and improve productivity.
Find out more about the IRT.
Previous articleLast updated April 29, 1997
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