Structure turbulent flow behind a square cylinder with an angle of incidence

Abstract This article shows the results of a study of the structure of turbulent flow behind a square profile ALUTEC 45 × 45 mm with T-slots. The angle of rotation of the profile relative to its axis varied α = 0 ° , 15 ° , 30 ° and 45 ° . During the experiment, the flow velocity was 5 m⋅s − 1 , Reynolds number was 7 . 7 ⋅ 1 0 4 . The Constant Temperature Anemometry technique was used for experimental studies. To avoid backflow, the measuring plane was positioned at the rear of the profile at a distance of x ⋅ d − 1 ≈ 2 . 2 . As a result of the studies, it was found that the highest Taylor microscale Reynolds number and standard deviation for turbulent flow was observed in the area behind the cylinder. The width of this area is 3.5 times the width of the cylinder. With the distance from the center of the cylinder in the spanwise direction to flow the Taylor microscale Reynolds number and standard deviation sharply decreases. The maximum values of the Taylor microscale Reynolds number are observed at α = 45 ° is 426 and 398. It has also been found that behind the cylinder there is some area in which the some parameters of the turbulent flow vary greatly with the change angle α . The lowest energy dissipation rate in this range is observed for α = 15 ° − 68 m 2 ⋅ s − 3 and the largest for α = 0 ° − 138 m 2 ⋅ s − 3 . We also found that the minimum value of the Kolmogorov scale and the Kolmogorov time is observed at α = 0 ° . The minimum values of the Kolmogorov scale η = 71 μ m and the Kolmogorov time τ η = 0 . 33 ms . The maximum values for previous parameters observed at α = 15 ° is η = 84 μ m and τ η = 0 . 47 ms . We also found that the flow rate and standard deviation distributions between the ALUTEC profile and the ordinary square cylinder different. This can be observed when the upper part of the profile is tightly closed and the lower part is open. In this case, along with the profile inside of the T-slot, there is a generation of internal flow. This reduces the total backflow area behind the ALUTEC profile by 20% compared to an ordinary square profile.