Magnetohydrodynamic Energy Bypass Research Articles

Annular Magnetohydrodynamic Physics for Turbojet Energy Bypass

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.

Comment on "Analysis of the Magnetohydrodynamic Energy Bypass Engine for High-Speed Airbreathing Propulsion"

Comment on "Analysis of the Magnetohydrodynamic Energy Bypass Engine for High-Speed Airbreathing Propulsion"

Comment on "Analysis of the Magnetohydrodynamic Energy Bypass Engine for High-Speed Airbreathing Propulsion"

Comment on "Analysis of the Magnetohydrodynamic Energy Bypass Engine for High-Speed Airbreathing Propulsion"

Analysis of Magnetohydrodynamic Control of Scramjet Inlets

Magnetohydrodynamic (MHD) control of forebody flow compression and air mass capture in scramjet inlets is analyzed for flight at Mach 5‐10. Because of the low static temperature, nonequilibrium electrical conductivity is created by electron beams injected into the gas along magnetic field lines. Two-dimensional inviscid steadystate flow equations are solved jointly with equations describing electron-beam-induced ionization profiles, plasma kinetics, and MHD effects. Among several scenarios considered, the scenario with an MHD accelerator has only disadvantages. A modest increase in mass capture can in principle be accomplished with a Faraday MHD generator, if the magnetic field has components both parallel and orthogonal to the flow. The principal focus is on MHD inlet control at flight Mach numbers higher than the design value. The shocks that would otherwise enter the inlet can be moved back to the cowl lip by placing an MHD generator at one of the compression ramps. Analysis shows that the best performance of such a device is achieved with a very short MHD region placed as far upstream (close to the vehicle nose) as possible, in conjunction with a high-current ionizing electron beam. An MHD energy bypass scenario with on-ramp MHD generator for inlet control is briefly discussed.

Analysis of the Magnetohydrodynamic Energy Bypass Engine for High-Speed Airbreathing Propulsion

The performance of the MHD energy bypass air-breathing engine for high-speed propulsion is analyzed in this investigation. This engine is a specific type of the general class of inverse cycle engines. In this paper, the general relationship between engine performance (specific impulse and specific thrust) and the overall total pressure ratio through an engine (from inlet plane to exit plane) is first developed and illustrated. Engines with large total pressure decreases, regardless of cause or source, are seen to have exponentially decreasing performance. The ideal inverse cycle engine (of which the MHD engine is a sub-set) is then demonstrated to have a significant total pressure decrease across the engine; this total pressure decrease is cycle-driven, degrades rapidly with energy bypass ratio, and is independent of any irreversibility. The ideal MHD engine (inverse cycle engine with no irreversibility other than that inherent in the MHD work interaction processes) is next examined and is seen to have an additional large total pressure decrease due to MHD-generated irreversibility in the decelerator and the accelerator. This irreversibility mainly occurs in the deceleration process. Both inherent total pressure losses (inverse cycle and MHD irreversibility) result in a significant narrowing of the performance capability of the MHD bypass engine. The fundamental characteristics of MHD flow acceleration and flow deceleration from the standpoint of irreversibility and second-law constraints are next examined in order to clarify issues regarding flow losses and parameter selection in the MM modules. Severe constraints are seen to exist in the decelerator in terms of allowable deceleration Mach numbers and volumetric (length) required for meaningful energy bypass (work interaction). Considerable difficulties are also encountered and discussed due to thermal/work choking phenomena associated with the deceleration process. Lastly, full engine simulations utilizing inlet shock systems, finite-rate chemistry, wall cooling with thermally balanced engine (fuel heat sink), fuel injection and mixing, friction, etc. are shown and discussed for both the MHD engine and the conventional scramjet. The MHD bypass engine has significantly lower performance in all categories across the Mach number range (8 to 12.2). The lower performance is attributed to the combined effects of 1) additional irreversibility and cooling requirements associated with the MHD components and 2) the total pressure decrease associated with the inverse cycle itself.

Implementation of magnetohydrodynamic energy bypass process for hypersonic vehicles

The global political structure has changed dramatically since the breakup of the former Soviet Union, and world changes have caused the United States to reprioritize its national hypersonic needs. The US Government has looked at the needs of the future, and the hypersonic aerospace plane is one of the systems included in alternative force structures. One hypersonic aerospace plane concept would involve magnetohydrodynamic (MHD) technology (i.e., the AJAX hypersonic flight vehicle concept) originally proposed by Russian scientist Vladimir Fraishtadt. This paper reports on the current progress and findings of an air-breathing horizontal takeoff and landing design concept using an MHD energy bypass injector ramjet engine being studied at MSE Technology Applications, Inc., HyperTech Concepts, and several universities for the National Aeronautics and Space Administration Langley Research Center under a Phase II Small Business Innovation Research project. The areas that are addressed in this paper include: (1) ionization required to achieve the required energy bypass, (2) utilization of a nonequilibrium model to calculate nonequilibrium engine ionization conditions, (3) hydrocarbon fuel reforming, and (4) vehicle performance and sizing. A quasi-onedimensional electromagnetic code combined with a new scramjet model, as well as other tools, were used to examine total system performance.

Theoretical Performance of a Magnetohydrodynamic-Bypass Scramjet Engine with Nonequilibrium Ionization

The theoretical performance of a scramjet propulsion system in which a magnetohydrodynamic (MHD) energy bypass scheme is operated in a nonequilibrium ionization environment is evaluated. In the MHD generator, the incomingairflow at a temperature too low to produce the required ionization is seeded with cesium and ionized by the use of an unspecified external power source. The resulting nonequilibrium environment is described using a two-temperature model. The accelerator is operated with equilibrium ionization. The expansion through the nozzle is calculated with account taken of finite rate reactions, and the boundary layer is assumed to be fully turbulent. The results show that the required external power is of the same order of magnitude as that of the power generated in the MHD generator. An MHD energy bypass propulsion scheme looks to be more promising with the equilibrium ionization method than with the nonequilibrium ionization method.

Magnetohydrodynamics Energy Bypass Scramjet Performance with Real Gas Effects

The theoretical performance of a scramjet propulsion system incorporating a magnetohydrodynamic (MHD) energy bypass scheme is calculated. The one-dimensional analysis developed earlier, in which the theoretical performance is calculated neglecting skin friction and using a sudden-freezing approximation for the nozzle e ow, ismodie edtoincorporatethemethodofVanDriestforturbulentskinfrictionandae nite-ratechemistrycalculation inthenozzle.Unlikeintheearlierdesign,inwhichfourrampcompressionsoccurredinthepitchplane,inthepresent design the e rst two ramp compressions occur in the pitch plane, and the next two compressions occur in the yaw plane.Theresultsforthesimplie ed designofaspacelinershowthat1 )skinfrictionsubstantiallyreducesthrustand specie cimpulse and 2 )the specie c impulseof the MHD-bypass system isstill betterthan the non-MHD system and typicalrocketoverarangeofe ightspeedsanddesignparameters.Resultssuggestthattheenergymanagementwith MHD principles offers the possibility of improving the performance of the scramjet for the spaceliner application and for the globecruiser application. The technical issues needing further studies are identie ed.