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

Abstract

Results are given of experimental and numerical investigations of plasma of products of combustion of pyrotechnic fuel [(64–69%)Mg+(35–30%)KNO₃+1% process additions] in air for the oxidizer excess coefficient α in the range from 0.8 to 1.1 and for different conditions in the combustor and MHD channel. The choice of the optimal formula of pyrotechnic fuel for use in experiments is analyzed and validated. The structural scheme and description are given of the Pamir-0-KT experimental facility. The operating time of the MHD facility was 3.6 s, with the flow rate of combustion products of about 2 kg/s at a pressure in the plasma generator of p _ch ≈ 4 MPa. The maximal value of the MHD-channel cross-section average plasma conductivity of 23 S/m at an electron mobility of 0.45 T⁻¹ is obtained for the composition of pyrotechnic fuel of 64%Mg+35%KNO3 at α = 0.96, pressure of 0.08 MPa, temperature of 2700 K, and flow velocity of 1900 m/s. It is demonstrated numerically that the value of conductivity σ₀ in the flow core is at least 50 S/m. The dependences of electrode voltage drops on current density are determined. The possibility is demonstrated of non-contracted flow of current to the surface of “cold” (800 K) electrode at average current densities up to 3×10⁴ A/m² and α ≈ 0.9.