Boundary-layer control on a body of revolution with a large aspect ratio by means of distributed air blowing

Results of studying the process of air blowing through a perforated section of the surface on an axisymmetric body with an aspect ratio of 25.3 in an incompressible flow with the Reynolds number Re_L = 4.36·10⁶ are reported. The blowing coefficient C_b is varied in the interval from zero to 0.00885. It is shown that distributed blowing through a perforated wall with improved geometry ensures a significant gain in friction drag as compared to that for the base configuration. Beginning from the frontal boundary of this section and further downstream, stable reduction of local friction is observed, which reaches 72 % directly in the region of blowing with the maximum intensity. In view of the energy expenses on the blowing process, the degree of energy saving can reach 1.4 to 6.1 % for the blowing region being located on the cylindrical part of the model. The efficiency of this method of boundary layer control can be refined by a more accurate determination of the contribution of the drag component induced by the pressure and friction forces on the frontal part of the body. The importance of estimating the possibility of using the proposed approach for the case of air blowing through a surface section on the frontal part of the body is noted.