Structures control with the use of the throttling effect, vortex cells and surface generators - Inclined oval-trench dimples

A promising scientific direction in aerohydromechanics related to structure control is discussed. The combination of structural elements with generated jet-vortex structures makes it possible to intensify the transfer processes and sometimes radically improve the aerodynamic and thermophysical characteristics of technical and energy systems. As examples, we consider the control of the flow around thick bearing surfaces when changing the position of the vortex cell using the throttling effect to intensify the flow circulating in the cell, as well as anomalous intensification of the separated flow and heat transfer in dense single-row packets of oval-trench dimples on the wall with varying orientation angle dimples to a turbulent flow in a narrow channel. The stabilization of the flow around a thick 37% Göttingen airfoil with the location of the vortex cell in the trailing edge region is established. Turbulent heat transfer in a narrow rectangular channel 7 to 1 was calculated on a stabilized hydrodynamic section at Re = 3333 with a single-row OTL packet with a depth of 0.25 with a step between dimples 3. The influence of the oval-trench dimples inclination angle ? in the range from 30° to 56° was analyzed. The angle ? of about 55° is close to optimal, and the relative thermal efficiency approaches 100% with a 55% increase in hydraulic losses. The optimal angle ? corresponding to the highest thermohydraulic efficiency turned out to be close to 48°. The local maximum of the 4-fold increase in the relative heat transfer coincides with the local maximum of the static pressure inside the separation zone in the area of increasing relative friction after it reaches its minimum values, reaching -3.4.