2013 1(12)

ON THE CONTROL OF 3D TURBULENT BOUNDARY LAYER SEPARATION USING LOCAL VOLUMETRIC AND SURFACE GAS HEATING

Shalaev V.I.

Moscow Institute of Physics and Technology (State University), Dolgoprudny, Russia

The flow control over individual aircraft parts by an influence to the flow with different physical mechanisms to enhance aerodynamic characteristics is one of perspective and developing directions of the modern aerodynamics. At the present time, possible techniques of directed flow change, particularly, some types of electric discharge are intensively studied. Although experimental works play the main role to study a mechanism of a discharge influence to the flow and to estimate its effectiveness, preliminary theoretical results are very useful, since they allow extracting a critical parameter value region, and then allow reducing the time and the cost of experiments. 

In the present work, results of theoretical and numerical modeling of electric discharge effect to 3D turbulent boundary layer separation on a slender cone are presented. Estimations of separation control using local surface heating are made also. The goal of this study is control of flow asymmetry, which arises spontaneously over aircraft head parts when a critical angle of attack is achieved.

To analyze the 3d turbulent boundary layer flow the local self-similar approximation for conical flow and Cebeci-Smith turbulent viscosity model are used. Although the turbulent boundary layer on a cone doesn’t self-similar, this approximation is agree well enough with full equation numerical solutions, it allows reducing essentially the calculation time and can be used as a first order approximation to evaluate physical effects. At the discharge modeling the main form of its influence on the flow is assumed to relate with the heat release. Therefore the discharge is modeled as a heat source, the configuration of which is defined with using of known data and physical considerations. The ionization effect doesn’t take into account since the ionization coefficient is small value of the order of 10–5. The intensive heating leads to arising of boundary layer – outer flow interaction effect near discharge or local surface heating regions. This effect doesn’t considered since a goal of the work is to demonstrate the principal possibility of the local heating influence to the boundary layer.

The problem of the discharge interaction with the boundary layer contains many parameters. To determine its rational set allowing effective control of the separation location the wide parametric studies were conducted. In this report, some results for heat-insulated surface are presented at the relative angle of attack , which is close to the critical value of the transition to asymmetric flow. The dependence of separation location from heat source intensity is obtained and the region of effective flow control is defined; the required power is evaluated. Calculated dependencies of separation location from the temperature of local surface heating are presented for 3 è 4. 

The presented results shown that the electric discharge is more effective method of separation control than local surface heating.

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