Separation Control On A NACA 0015 Hydrofoil Using Lorentz Forces

The use of electromagnetic forces to control the flow of electrically
conducting fluids is mostly associated with highly conducting liquids
like liquid metals and semiconductor melts. Only recently,
Electro-magnetic Flow Control for fluids of low electrical
conductivity like seawater has gained increasing interest. Most of the
published experimental and numerical work in this emerging field is
dedicated to skin friction reduction in turbulent boundary layers.

The present paper is focused on utilizing the accelerating effect of a
streamwise Lorentz force to prevent flow separation at the suction
side of a NACA 0015 hydrofoil. While the basic effects of
separation suppression and circulation enhancement have been
shown in [1], we will concentrate on the comparison of the
experimental results with such of separation control by steady
blowing. For this purpose, the Lorentz force strength will be given in
terms of an electromagnetic momentum coefficient C_EMHD, describing
the ratio of the total electromagnetic force imposed on the flow to
the product of dynamic pressure and wing area. Force measurements in
the Reynolds number range 2.9 10E4 < Re < 3.7 10E5, obtained with 3
different hydrofoils will be used to give a first approximation of the
maximum lift gain in dependence upon Reynolds number and Lorentz
force. Again, the electromagnetic momentum coefficient seems to be an
acceptable correlation factor to describe the control effect of the
Lorentz force in different flow configurations.