A compressible mixing layer facility for CFD validation measurements

The motivation for this work is the documentation of the design and fabrication of a new intermittent-blowdown compressible shear layer wind tunnel. The construction of this facility was motivated by the need for high-quality benchmark experimental data of the compressible mixing layer phenomenon for use in computational fluid dynamics (CFD) validation. This need has arisen because of improved computational capability and the practicality of high resolution flow simulation techniques of the turbulent compressible mixing layer flow field by means such as large-eddy simulations (LES) and direct numerical simulations (DNS), and the maturation of high-resolution laser-based flow diagnostic techniques such as stereo particle image velocimetry (SPIV). The newly developed facility is characterized by its two-stream design (a sonic/supersonic primary stream and a subsonic secondary stream), which are separated by a stainless steel splitter plate that ends coincident with the start of the mixing layer test section. A major design emphasis was placed on unobstructed optical access to the test section, where the mixing layer development occurs and where the accurate and complete measurement of the flow field is critical. The design of the nozzles and the test section divergence mechanism was performed iteratively through direct input from CFD and finite element analysis (FEA) simulation results. Complete dimensioning and design specifications of the new facility and full assembly will be made available to the academic and technical communities via an online catalog of fully-dimensioned engineering drawings for the as-built design.