Convective flows stability at the isothermal diffusion mixing of ternary gas mixtures

Analysis of the experimental data for the study of mechanical equilibrium instability by the diffusion mixing of ternary gas mixtures in isothermal conditions is carried out within the linear theory of stability. A channel is considered in the form a vertical cylindrical channel of a final height at the boundary conditions implying the absence of components’ transfer through the diffusion channel walls. Predictions of the theory are compared with the experimentally determined location of stability borders for the mixture 0.4722 He + 0.5278 Ar – N 2 by a variation for different diameter of the channel. The existence of the intensity maximum of components’ transfer in dependence on the thermodynamic parameters under conditions of the developed convection connects with the mode of disturbances determining the various types of convective flows. Structural formations moving opposite to each other which numbers are defined by the mode of disturbances in the cross-section of the diffusion channel interacts and thereby defines the wave-like change of unstable process intensity. For the examined system first maximum of the unstable process intensity subject to the diameter appearing at d = 6 mm is characterized by the mode of disturbances n = 3 and the critical Rayleigh number R 3 = 972.7. Stabilization of the convective transfer defining by the certain motion type of convective forming i.e. the motion along six channels (three flows and three counterflows) occurs under such conditions. Also, results reveal that increase of the mode of disturbances and the diameter of diffusion channel result in the non-linear increase of the critical Rayleigh number for all components taking part in the transfer. Further, the present results are in good agreement with the experimental data for the system 0.4722 He + 0.5278 Ar – N 2.