Annular Magnetohydrodynamic Physics for Turbojet Energy Bypass

Abstract

A methodology is presented to analyze the potential benefits of magnetohydrodynamic energy bypass of a turbojet. The methodology is demonstrated with an analysis of a hypothetical high-flight-Mach-number air-breathing engine. The annular magnetohydrodynamic generator and accelerator ducts that are analyzed rely on nonequilibrium ionization to assess their major design parameters. The analysis is conducted with the one-dimensional, axisymmetric magnetohydrodynamic equations, which are numerically integrated to determine performance characteristics. The cycle analysis is conducted iteratively with the components of the engine, which include a spike inlet, magnetohydrodynamic generator, standard Brayton cycle turbojet (compressor, combustor, and turbine), and magnetohydrodynamic accelerator. The Mach 7, 30-km-alt flight condition yields an estimated specific thrust of at an aggressive 2200 K combustor temperature, where the break-even specific thrust point is at a combustor temperature of 2000 K. The predicted magnetohydrodynamic devices are 3 m in length with 5 T magnetic fields and conductivities of 1 to . The calculated isentropic efficiencies are 84% for the generator and 81% for the accelerator with 63% enthalpy bypass. Based on this analysis, areas of future research are highlighted that are vital for successfully implementing the proposed magnetohydrodynamic turbojet.