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Abstract This work aims to improve the visualization of a subsonic open section type smoke tunnel, which already exists in the AL-Nahrain University/College of Engineering/Mechanical Department Laboratory. This study focuses on modifying the contraction section only to improve the airflow properties in the test section. A numerical study with ANSYS FLUENT R19.0 was carried out to characterize the flow via the contraction section. The parameters that are suggested to be modified are the wall profile and the length of the contraction section. The analysis includes the original contraction section and suggested new profiles to be compared under the same boundary conditions. The new suggested profiles for this work are polynomials of orders (6 th , 7 th , 8 th , 9 th , and 10 th ). A unique analysis is achieved for the 9 th order profile, where it is tested with four different inflection points (0.5L, 0.55L,0.6L, and 0.65L). The study focuses on the uniformity, turbulence intensity, boundary layer thickness at the contraction section exit plain, beside the boundary layer separation along with the contraction as comparing parameters. Experimental work was done to validate the numerical results. The experiment work includes building a half-scale of the original smoke tunnel to monitor the new contraction’s direct influence on the test section’s flow. The result showed that the 9 th -order wall profile with an inflection point at 0.65L and length of 0.93m is the pest contraction for the aimed smoke tunnel.
Kareem et al. (Mon,) studied this question.