Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
Computational Fluid Dynamics is used as a tool for optimizing a model wind tunnel three-dimensional contraction. A sixth order polynomial profile is chosen with six conditions to determine the polynomial coefficients. The seventh condition is the location of the inflection point along the contraction axis. Five inflection points are chosen to give five different contractions. Numerical simulations for the five contractions are carried out, Reynolds number based on the free stream velocity and the test section height is 1.3X10^6. Boundary layer thickness, static pressure and secondary flow are considered as optimization parameters. Numerical results show that boundary layer thickness decreases, variation in wall normal velocity components at the test section inlet increases, and probability of flow separation increases as the inflection point moves towards the contraction outlet. Unlike recent numerical studies, numerical results of this work indicate that the optimum profile for the contraction is when the inflection point is located at the middle of the contraction, thus the sixth order polynomial reduces to a fifth order.