Flow Matching Results of an MHD Energy Bypass System on a Supersonic Turbojet Engine using the Numerical Propulsion System Simulation (NPSS) Environment

Abstract

Flow matching has been successfully achieved for an MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment helped perform a thermodynamic cycle analysis to properly match the flows from an inlet employing a MHD energy bypass system (consisting of an MHD generator and MHD accelerator) on a supersonic turbojet engine. Working with various operating conditions (such as the applied magnetic field, MHD generator length and flow conductivity), interfacing studies were conducted between the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis. This paper further describes the analysis of a supersonic turbojet engine with an MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to a range of 0 to 7.0 Mach with specific net thrust range of 740 N-s/kg (at ambient Mach = 3.25) to 70 N-s/kg (at ambient Mach = 7). These results were achieved with an applied magnetic field of 2.5 Tesla and conductivity levels in a range from 2 mhos/m (ambient Mach = 7) to 5.5 mhos/m (ambient Mach = 3.5) for an MHD generator length of 3 m. Nomenclatureγ specific heat ratio for air η N(a) enthalpy addition ratio of the MHD accelerator η N(g) enthalpy extraction ratio of the MHD generator η s (a) isentropic efficiency for the MHD accelerator η s (g) isentropic efficiency for the MHD generator π a stagnation pressure ratio of the MHD accelerator π g stagnation pressure ratio of the MHD generator π p stagnation pressure ratio of the pre-ionizer σ electrical conductivity χ fraction of MHD generator power diverted to pre-ionizer A g cross sectional area of the MHD generator B magnetic field intensity C p constant pressure specific heat K Faraday loading parameter L length of the MHD generator m  mass flow rate of the air and fuel through the turbojet M entrance Mach number at the entrance of a component M exit Mach number at the exit of a component P elec power output of the MHD generator P elecA power input into the MHD accelerator T 0,12 stagnation temperature at the entrance of the MHD generator NASA/TM-2011-217136 2 T 0,14 stagnation temperature at the exit of the MHD generator T 0,58 stagnation temperature at the entrance of the MHD accelerator T 0,6 stagnation temperature at the exit of the MHD accelerator T 0,entrance stagnation temperature at the entrance of a component T 0,exit stagnation temperature at the exit of a component v velocity of flow IntroductionThe magnetohydrodynamic (MHD) energy bypass system has been proposed (Ref. 1) to provide benefits for aeropropulsion systems. It is anticipated that combining technology developments in electromagnetics, aerodynamics, and chemical kinetics may lead to a breakthrough for improving aerospace vehicle performance. A growing interest is evident...