AJAX MHD Plasma

Looking for photos of Russian AJAX. At hyper speeds AJAX uses plasma to generate power to operate the MHD generator which in turn controls the plasma around the spaceplane. Full circle Enthalpy!

Here you go.

BTW, your post makes it sound like this is a current and happening thing.
In actuality there are no indications that there has been work on this project in recent years, although there is talk about trying to start a joint Indian/Russian hypersonic plane project.

There's a good reason development hasn't continued: it won't work. It certainly won't work with today's materials and technology and there's a convincing argument that so-called "inverse Brayton Cycle engines" are thermodynamically flawed from the start. Someone could probably make one fly, but it won't be as efficient as a normal ram- or scramjet.

Don't get me wrong, someone may decide that the benefits of being able to extract or add energy in certain areas of a high speed flow will outweigh the costs, but it's been pretty much laid to rest that the simple concept of drawing energy out of an engine upstream of the burner and adding it back downstream is a non-starter.

MHD development in Russia most likely stopped due to lack of funding
(soviet collapse) not a technology barrier. Minimizing Enthalpy loss is what makes hypersonic flight possible. All energy must be utilized even the energy that was stored in the fuel “hydrogen" from chilling it. The vehicle in essence becomes an energy transfer machine. LACE MHD it’s all about utilizing the energy in and around the vehicle. This is what makes a truly successful design. MHD is not dead its just hibernating until western hypersonic technology catches up with it. The Russians we’re way ahead of the USA in this area.

Originally posted by Retro
Looking for photos of Russian AJAX. At hyper speeds AJAX uses plasma to generate power to operate the MHD generator which in turn controls the plasma around the spaceplane. Full circle Enthalpy!

And totally and utterly against the laws of physics - there has to be an input of energy somewhere otherwise the energy involved in the cycle will decrease to the point where it becomes a rest state,

Originally posted by Retro
MHD is not dead its just hibernating until western hypersonic technology catches up with it.

There are several technological barriers preventing effective MHD systems from being fielded. MHD is certainly a way to add energy to a high speed flow or extract energy from the flow, and there may be benefits of doing this. Obviously if you need large amounts of electrical power (for a directed energy weapon for example) you could use an MHD generator to power it (and you'd take a huge drag hit when it was turned on). But the efficiency of such a device as well as the weight penalty associated with it make even such a straightforward application of MHD too risky for production systems today. It's just not a mature enough technology at this point.

For more complex implementations of MHD, such as an inverse Brayton Cycle engine or flow field modification around an airframe there are even greater problems. I'm not aware of any system that even makes sense on paper, let alone in the real world. As I hinted in a previous post, the inverse cycle engine concept is fundamentally flawed. The simplest way to understand why is to realize that in a conventional Brayton Cycle engine (like a turbojet), work is added upstream of the burner (via a compressor) to increase the temperature and pressure of the flow in the burner. Obviously the power has to come from somewhere so there is a turbine downstream of the burner that powers the compressor. It is good from a thermal efficiency standpoint to have heat addition in the burner at a high temperature and pressure, and that's why turbojets are successful engines. In an inverse cycle engine, an MHD system would extract energy upstream of the burner and then that energy could be added back to the flow downstream of the burner. This has an apparent benefit of reducing the enthalpy of the flow in the burner which might allow you to add more heat there and still not melt the structure of the engine, but as it turns out the basic cycle loss caused by the reduced thermal efficiency of the burner results in an engine that is less efficient than a similar engine without the MHD devices (i.e. a normal ramjet or scramjet). Then you have to factor in the weight and efficiency of the MHD equipment, which are not trivial, and you realize pretty quickly that there's no point. Just build a scramjet and it will be better in nearly any conceivable flight regime.

Originally posted by RichardPrice
And totally and utterly against the laws of physics - there has to be an input of energy somewhere otherwise the energy involved in the cycle will decrease to the point where it becomes a rest state

Retro misspoke in his first post, the concept is to use an MHD generator to power another MHD device that modifies the flow field. It could also be used in an inverse cycle engine as I described above. In either case there is still heat added by burning fuel to power the engine. There's no physical law being broken since one device extracts or "generates" power from the flow (with some loss and entropy generation) and then another device imparts that power somewhere else in the flow (again with entropy generation).

Great discussion! Certainly challenges the MHD application. If I recall the Russian AJAX utilized a complex chemical reaction combined with MHD which would allow hydrocarbon propulsion to reach extremely high mach numbers. Well beyond the current mach 8 coking and thermal barrier. The ability to control inlet compression and combustion with magnetic waves is well demonstrated. Morphing the plasma field and shock waves surrounding the vehicle could be used to change the trajectory without using control surfaces. I believe MHD tech warrants further investigation. And I suspect interest will be reignited in the not to distant future. Many hypersonic theories remain to be proven and validated.