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INL has developed the world's largest Matched-Index-of-Refraction (MIR) flow system for conducting basic and applied studies on:

• complex turbulent and transitional flows
• flows in porous media — 930kB PDF
• two-phase particulate flows

using optical techniques. The large size permits better spatial and temporal resolution of flow structure than previous MIR applications.

The largest Matched-Index-of-Refraction flow system in the world was designed and built at INL.

INL scientists and engineers use the MIR system to support DOE programs in advanced reactor systems and safety issues dealing with spent nuclear fuel as well as university, Federal laboratory and industry research projects.

The MIR facility, located at the INL Research Center in Idaho Falls, Idaho, enables laser-doppler velocimetry and particle tracking measurements. When light travels through a region of non-uniform refractive index, it bends in different directions depending on the local refractive index and the angle it makes with the interface between the two media. Thus, the presence of walls, the test object itself or other physical elements located near or inside the measurement volume can distort or disturb the measurements. The MIR facility eliminates this optical interference through the use of physical models made of a transparent solid material, and use of a fluid with the same refractive index as the solid model. In this way, the model disappears optically but maintains its full dynamic influence on the fluid flow.

Recent studies ( 1.9MB PDF) with INL's MIR flow system include the evolution of laminar-to-turbulent boundary-layer transition ( 306kB PDF) induced by a rib, flow in an idealized spent nuclear fuel (SNF) ( 90kB PDF) canister, coolant passages in high temperature gas-cooled reactors ( 204kB PDF), flow around buildings ( 82kB PDF), near-wall flow over realistic roughness in turbomachinery passages and complex coolant geometries for supercritical (pressure) water reactors ( 334kB PDF). Upcoming experiments include the scaling of synthetic jets ( 151kB PDF) and multiphase flow in subsurface fractures ( 421kB PDF). Applications range from micro-scale to building-scale.

INL welcomes opportunities to collaborate with researchers at universities, other national laboratories and with industry. Please contact the individual listed below to make arrangements to use our facility.