Influence of a vertical electric field on the mixing layer of two gas flows with different densities

• Published in: Experimental thermal and fluid science 1994, Vol.8 (2), p.158-166
• Main Authors: Ambartsoumian, E.N., Nesterov, S.V., Rudenko, A.O.
• Format: Article
• Language: English
• Subjects: density stratification; Electric field; mixing layer; ponderomotive forces; vibrations; visualization; wave generation; wind tunnel
• ISSN: 0894-1777; 1879-2286
• DOI: 10.1016/0894-1777(94)90043-4

The work has been conducted as a part of the scientific program associated with ecological problems and analysis of atmospheric phenomena. It contains two parts describing investigations of interaction between electric fields and flows. In the first part, the loss of stability of the horizontal boundary between two liquids (water and kerosene) in a vertical electric field is investigated both theoretically and experimentally. Such as electrohydrodynamic system displays stochastic and regular vibrational modes that can be transformed into each other by varying the applied electric field. The possibility of application of constant and varying electric fields for simulating the generation of waves in a liquid by low-pressure regions is demonstrated. A theoretical description of the process of emergence of auto-oscillations is given by using the linear theory of waves existing at the boundary between two heavy ideal liquids. The second part of the work is devoted to the experimental investigation of less common phenomena occurring in the transient layer of mixing of gas flows with different densities (air + helium) under the influence of a constant electric field. A plane density-stratified layer was created in the channel of a gas stratification setup. A constant electric field of a capacitor was applied to the gas flow producing this layer. In zero field, the plane layer remained stable and parallel to the capacitor plates. In a nonzero field, the layer in the capacitor (as well as the downstream layer) was turbulized or destroyed completely, depending on the field strength. A remarkable effect was observed in the upstream direction. At a large distance from the capacitor, the plane layer was turbulized; starting from a certain threshold value of the electric field strength, the plane layer was deflected from the equilibrium position and deformed. The nature of this effect has not been clarified completely. In all probability, the reason behind the effect lies in the interaction between the electric field in the capacitor and a weakly charged gas flow whose electrification may be due to the leakage of charges from the edges of the capacitor plates. The long-wave perturbation observed in the upstream direction outside the capacitor is apparently an internal wave propagating in the density-stratified layer.