Magnetohydrodynamic Turbojet
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Magnetohydrodynamic Turbojet
Ok lads (and any ladettes viewing)
A new way proposed below of extending the operating regime of turbojets to Mach 3+ ...the point where a scramjet can light...
If I am reading it right... you extract electromagnetic energy from the airflow entering the turbojet (thereby slowing the airflow to ~mach 2.5). The electromagnetic energy is then used to excite ions in the exhaust... massively increasing the energy output? Sort of like an electromagnetic afterburner?
Any ppruners with technical expertise pls comment.
"The idea is to extend the operating range of turbomachinery to higher Mach numbers," says Isaiah Blankson, a senior scientist at NASA Glenn Research Center. "We would put a device ahead of the engine to ionise the flow, extract the energy then put it back in the combustor."
By slowing the flow entering the inlet, the operating range of existing turbine engines could be extended to M7, from today's maximum of around M3. Extracting 30-40% of the total energy of the flow would reduce its speed by a half to three-quarters, he says, allowing the turbine engine to operate at M2.8.
The MHD energy bypass cycle was investigated, but not implemented, by the power generation industry in the USA and elsewhere in the 1950s and 1960s as a way of increasing electricity output at peak times. At that time, ionisation was achieved by seeding the flow with cesium. Later electron beams were proposed.
A new way proposed below of extending the operating regime of turbojets to Mach 3+ ...the point where a scramjet can light...
If I am reading it right... you extract electromagnetic energy from the airflow entering the turbojet (thereby slowing the airflow to ~mach 2.5). The electromagnetic energy is then used to excite ions in the exhaust... massively increasing the energy output? Sort of like an electromagnetic afterburner?
Any ppruners with technical expertise pls comment.
"The idea is to extend the operating range of turbomachinery to higher Mach numbers," says Isaiah Blankson, a senior scientist at NASA Glenn Research Center. "We would put a device ahead of the engine to ionise the flow, extract the energy then put it back in the combustor."
By slowing the flow entering the inlet, the operating range of existing turbine engines could be extended to M7, from today's maximum of around M3. Extracting 30-40% of the total energy of the flow would reduce its speed by a half to three-quarters, he says, allowing the turbine engine to operate at M2.8.
The MHD energy bypass cycle was investigated, but not implemented, by the power generation industry in the USA and elsewhere in the 1950s and 1960s as a way of increasing electricity output at peak times. At that time, ionisation was achieved by seeding the flow with cesium. Later electron beams were proposed.
Last edited by tartare; 30th Nov 2007 at 00:28. Reason: Now I understand...
Wunderbra
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Interesting. I'd like to see how they propose to ionise that quantity of air, and what the energy cost is. If the energy consumed to ionise the air is greater than the gain then I don't see it working. (do I get a prize for stating the bleeding obvious?)
The article mentions electron beams. What sort of eV energy would be required to ionise that kind of massive airflow?
And what about the weight penalties for the electron guns?
Would be very interesting to see more detail.
Of course, the big question is why? We don't currently have, nor are there planned, any supersonic, let alone hypersonic passenger aircraft. If it was for some kind of missile system or fighter then I could understand it, but it seems to fill a niche that simply doesn't exist in the civil industry. Of course it's possible that it might lead to improvements in fuel economy for normal jet engines.
The jury's out on this one for me.
The article mentions electron beams. What sort of eV energy would be required to ionise that kind of massive airflow?
And what about the weight penalties for the electron guns?
Would be very interesting to see more detail.
Of course, the big question is why? We don't currently have, nor are there planned, any supersonic, let alone hypersonic passenger aircraft. If it was for some kind of missile system or fighter then I could understand it, but it seems to fill a niche that simply doesn't exist in the civil industry. Of course it's possible that it might lead to improvements in fuel economy for normal jet engines.
The jury's out on this one for me.
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Specifically, Dr. Blankson is actively pursuing studies in the following areas:
MHD Energy Bypass Engine Concepts (Mach 0-7) based on conventional and exoskeletal gas turbine engines. Applications are to global-range cruise vehicles, two-Stage Space Access vehicles, and energy-on-demand hypersonic systems.
Weakly-Ionized Plasma (WIG) phenomena – aerodynamic and propulsion applications of WIG. (Electromagnetic Field interactions in hypersonic flows). Applications are to supersonic and hypersonic flow control, wave drag reduction, and sonic boom alleviation.
Airbreathing Hypersonic Cruise: WAVERIDER AIRCRAFT and CRUISE MISSILES. Airframe-integrated Mach 4-7 Hydrocarbon - fueled waverider aircraft/missiles, advanced waverider design concepts (inverse design methods). The emphasis is on unmanned autonomous high speed air vehicles: especially supersonic and hypersonic cruise missiles and UCAVS concepts using turbo ramjets.
MHD Energy Bypass Engine Concepts (Mach 0-7) based on conventional and exoskeletal gas turbine engines. Applications are to global-range cruise vehicles, two-Stage Space Access vehicles, and energy-on-demand hypersonic systems.
Weakly-Ionized Plasma (WIG) phenomena – aerodynamic and propulsion applications of WIG. (Electromagnetic Field interactions in hypersonic flows). Applications are to supersonic and hypersonic flow control, wave drag reduction, and sonic boom alleviation.
Airbreathing Hypersonic Cruise: WAVERIDER AIRCRAFT and CRUISE MISSILES. Airframe-integrated Mach 4-7 Hydrocarbon - fueled waverider aircraft/missiles, advanced waverider design concepts (inverse design methods). The emphasis is on unmanned autonomous high speed air vehicles: especially supersonic and hypersonic cruise missiles and UCAVS concepts using turbo ramjets.
Thread Starter
Ajax
Related... have a look at this people... very interesting. Ignore the title of the website.
http://www.americanantigravity.com/d...AX-Oct2002.pdf
http://www.americanantigravity.com/d...AX-Oct2002.pdf
