Simulation & Analysis: ABB’s Upgraded Variable Speed Drive Gives NASA’s Wind Tunnel a New Lease of Life

HAS BEEN USED TO TEST THE BOEING 777. In a recent project together with ABB, the American space agency NASA has modernized and upgraded the capacity of its NTF (National Transonic Facility) wind tunnel. The project is interesting, among other things, because it increases the lifespan of the wind tunnel by at least ten years.
NASA uses wind tunnels to test scale models of aircraft and spacecraft. Some wind tunnels are large enough to accommodate full-size versions of vehicles, and one of the points of the NTF type is that the wind tunnel moves air around an object, making it appear as if the object is actually flying.
The NTF wind tunnel is used to optimize aircraft performance and fuel consumption by simulating flight conditions at high altitudes and near the speed of sound. It has been used to test the Boeing 777, the Space Shuttle and its launch vehicle.
What makes the NTF wind tunnel unique in this respect is that it is the world's largest pressurized cryogenic wind tunnel, whose capacities provide unique opportunities to duplicate actual flight conditions. The tunnel supports complex aerodynamic concept development and assessment, advanced validation with fluid dynamic computational tools, and risk mitigation in the context of vehicle and aircraft development work. Moreover, it provides the highest transonic Reynolds number testing capability in the world and can use either conventional air at ambient temperatures, as the test gas, or gaseous nitrogen at temperatures as low as -250 ºF to achieve flight test conditions. With a wide range of customizable instrumentation and measurement techniques, both full-span and semi-span model testing is supported.
What ABB and NASA have now done is that they have upgraded a frequency converter which, among other things, means that they substantially extended the life of the NTF wind tunnel. The service project has also increased the reliability and availability of this world's largest medium voltage (MV) frequency converter system.
The background to the project is that in 2021, NASA engineers identified a need to upgrade the tunnel's medium voltage converter due to aging of the frequency converter's components. ABB delivered the frequency converter in 1997, and it was then the most powerful of its kind in the world. The 101 MW frequency converter can test models in supersonic air or nitrogen streams and at ambient or cryogenic temperatures. With that, NTF can thus simulate more different flight conditions than any other wind tunnel, which gives the engineers the opportunity to gain unique insights and refine the aircraft designs.
"NASA has relied on ABB's domain expertise to ensure NTF can provide high reliability and uptime for its test programs and optimize the lifecycle of its assets," comments Oswald Deuchar, Director of Modernization Services, ABB Motion. How did it all happen?