Boundary layer development in supersonic MHD generators

Experimental and numerical investigations of plasma of products of combustion of pyrotechnic fuel in air

“…Estimates for the GFT under consideration revealed that the values of the thickness of dynamic (δ) and thermal (δ t ) boundary layers on the insulating walls at the center of the electrode zone are close to the value of half-width a/2 of the MHD channel even in the case of hydraulically smooth walls (Fig. 3) [10,11]. The mode of loading of MHD generator was determined by matching the experimentally obtained and predicted values of electric field intensity E y at the center of the electrode zone for the known value of B 0 .…”

“…(4) Here, I a and I c denote the experimentally obtained values of currents of the anode and cathode of the nth section, respectively; l and a denote the length and width of an electrode section, respectively; u g∞ is the velocity of the gas phase in the flow core; E y = (U c + + ΔV Σ )/h, where U c is the voltage on the electrodes of the MHD channel, and ΔV Σ is the total electrode drop of voltage with measured values of current density on the anode and cathode; h is the spacing between the electrodes; and is the displacement thickness of current for the boundary layers on the insulating walls [10]. Expressions (1)-(3) are valid on condition of quasi-one-dimensionality of the flow of currents d Jx /dx ≈ 0, which is valid for close values of I an and I cn .…”

“…Expressions (1)-(3) are valid on condition of quasi-one-dimensionality of the flow of currents d Jx /dx ≈ 0, which is valid for close values of I an and I cn . The values of u g∞ and δ jiz , required to calculate σ 0∞ and μ e∞ , were determined using the Kanal computer codes for the calculation of two-phase quasione-dimensional flows and the method of numerical simulation of two-dimensional boundary layers in supersonic MHD generators [10,11]. The "geometric" conductivity σ 0gn (4) was used for comparison of the effectiveness of organization of combustion of CF with different compositions of PF (see Section 5).…”

Experimental and numerical investigation of the electrophysical properties of products of combustion of hydrogen in oxygen seeded with alkali metals

“…For the uncooled full-scale channel, the inclusion of the effect of the boundary layers results in an increase of calculated conductivity in the flow core by ≈3% in the inlet cross section and by ≈8% in the outlet cross section of the channel. For the cooled channels, additional calculations were performed of two-dimensional boundary layers in the gasdynamic flow train in view of the injection of cooling gas [11].…”

“…For each test, the experimentally obtained values of p comb , α, and g were used to calculate the respective values of electrical conductivity [9] in view of the effect of heat loss in the PG and of the displacement thickness of boundary layer in the measuring channel whose value was determined in a two-dimensional approximation [11]. Because the thickness of boundary layers turned out to be insignificant, their effect on the predicted value of electrical conductivity did not exceed 3%.…”