Patent ID: 6119987
Filing Date: 2000-09-19
Classification: B64C,F05D,F15D,F28F,Y02T

Abstract:
Method for controlling the boundary layer or the wall layer of a continuous medium comprising gases, liquids and/or their mixtures in the vicinity of a surface (1) for changing the flow structure, turbulence level, transfer of the impulse, transfer of heat or admixtures by influencing the flow and changing of velocities of continuous medium particles and causing formation of tornado-like vortex flow whereina continuous medium flow is influenced by a field of forces at least in its wall region within a range of distances yn along the normal from the surface (1),a turn of the velocity vectors of the continuous medium particles is caused repeatedly in space or in time by said influence of said forces,said influence causes said turn in a range of angles .alpha. alternately towards the surface (1) and from it away and in a range of angles .beta. alternately to the left and to the right with regard to the direction of the velocity vectors of the continuous medium particles of the near-wall flow, characterized in thatsaid range yn being from 0.005 to 0.3 times the boundary layer thickness .delta., or the equivalent hydraulic diameter of the pressure channel, or the characteristic hydraulic dimension of the near-wall flow;said angle .alpha. being between .alpha.=0.02 and 0.5 radian;said angle .beta. being between .beta.=0.02 and 0.3 radian;the intensity of said influence or the strength of said forces is such that the minimum curvature radius R.sub.min, of the trajectory of the flow of said particles is from 2 to 30 average distances S along the normal from the streamlined wall to the curved trajectory of the particle,whereas at least one of the following features a) and b) is valid:a) the spatial repetition of said influence being .lambda..parallel.=(3 to 30) yn along the direction of the wall flow and .lambda..perp.=(1 to 10) yn perpendicular to the direction of the wall flow,b) the time repetition T being from 3 to 30 times the distances yn divided by the average velocity v in the boundary or wall layers.