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

Abstract

Results are given of experimental and numerical investigations of electrical conductivity and mobility of electrons in the products of combustion of hydrogen-oxygen fuel seeded with cesium or potassium-sodium eutectic. The experiments were performed in model (flow rate of 0.9 kg/s, thermal power N th ≈ 7 MW) and large-scale experimental (flow rate ≈12 kg/s, N th ≈ 150 MW) facilities with the pressure in the combustor ranging from 2 to 6 MPa, oxidizer excess coefficients of 0.6 to 1.1, mass fractions of the seed in the fuel of 0.3 to 0.9 with the Mach number M ≈ 2.4. The basic characteristics, structural schemes, and general views of the facilities are given. When cesium is used for seeding, the experimentally obtained values of electrical conductivity may be as high as σ el ≈ 20 S/m, those of σ el v 2 ≈ 115 S/m (km/s) 2 , and of electron mobility -0.11 T -1 at a pressure of ≈0.3 MPa, temperature of ≈2800 K, and flow velocity v ≈ 2500 m/s. Under the same conditions for combustion products seeded with KNa eutectic, we have σ el ≈ 9 S/m, σ el v 2 ≈ 65 (S/m)(km/s) 2 , and electron mobility of 0.09 T -1 .

Open-cycle multi-megawatt MHD space nuclear power facility

“…Table 1 (variant 4, electric load factor at the entrance 0.55). The convective heat flux at the entrance into the channel at wall temperature 1500 K reaches 1.3 kW/cm 2 , which is higher than analogous flux for MHD generators operating on the products of combustion of hydrogen in oxygen [16].…”

“…An electricity converter must be included in the nuclear power facility in order to match the electric parameters of the MHD generator with the user (or accumulator) of electricity [1, 16,17]. Such a converter can increase the voltage to 100 kV.…”

“…Ground-based prototypes of such MHD generators already reach power levels up to 500 MW(e) with specific "dry" mass up to 0.1 ton/MW, energy conversion coefficient up to 15%, and power density up to 600 MW/m 3 . However, the specific energy extraction in them does not exceed 1 MJ/kg, which requires a substantial working-body mass in order to obtain a large amount of electric energy on-board.Energy facilities based on nuclear reactors, including with different types of MHD generators, are promising for solving space problems [2,[4][5][6][7][15][16][17].For powerful space nuclear energy facilities operating for a long time (≥1 yr), it is desirable to consider the possibility of using a closed cycle based on heterogeneous gas-cooled reactors and MHD generators based on nonequilibrium plasma [10,18]. In this case, it is sufficient to have a working-body (inert gas) temperature at the level 2000 K, which will make possible a gas-dynamic channel with a long service life.…”

“…Energy facilities based on nuclear reactors, including with different types of MHD generators, are promising for solving space problems [2,[4][5][6][7][15][16][17].…”

“…It is proposed that a reactor for the nuclear rocket motor with characteristics close to the experimentally completed IVG-1 reactor with thermal power reaching 220 MW(t) be used as the high-temperature nuclear reactor for the MHD system [3,15,20]. A prototype of a cooled Faraday MHD generator is a short-time action MHD generator using products of combustion of hydrogen in oxygen seeded with cesium or a sodiumpotassium eutectic [16]. Since the efficiency of MHD generators using equilibrium plasma and a linear channel is now ≥10%, the electric power of the system will be ≥20 MW(e) [12,13].…”