Experimental investigations of the influence of coating consist of streamwise slots with different spacing and depth on second mode disturbances in hypersonic boundary layer of the sharp cone at Mach number M∞ = 5.8 are conducted. The experiments show that the second mode disturbances are dumped on the surfaces with slots. It is found out that the maximum amplitude of the second mode versus depth has the nonmonotonic dependence. Minimum of the second mode disturbances amplitude are found for depth h = 0.6 mm for the coatings with slots width w = 0.2 mm and spacing b = 0.4 and 0.8 mm. The coatings consists slots with spacing b = 0.4 mm suppress disturbances better than coatings with b = 1.8 mm. Maximum of the disturbances growth rate on the surface with slots are shifted to the lower frequency. It is shown that surfaces consisting of streamwise slots effectively stabilizes the second mode disturbances, which is the most unstable in the hypersonic boundary layer, and destabilizes perturbations with lower frequencies related to the first mode disturbances.
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