Aerojet / Pyrodyne - Pyrojet and Trijet Turbine Based Combined Cycle (TBCC) engines

Here is a link to a picture of the system at Aerojet's website. Look under capabilities/airbreathing propulsion. I have not heard of Pyrodyne nor this system. Supposed to be able to operate from 0 to Mach 10 as a single integrated engine platform, interesting.

I'm looking at the pic and seeing the obvious inward-turning inlet (looks like it might be elliptical cross sections going by the shading) and big nozzle, but I'm trying to figure out how it shields the turbine engine at the high Mach numbers. Something seems missing, at least from the side 'cross section' view.

Some kind of mach diamond shadowing?

bobbymike said:

Here is a link to a picture of the system at Aerojet's website. Look under capabilities/airbreathing propulsion. I have not heard of Pyrodyne nor this system. Supposed to be able to operate from 0 to Mach 10 as a single integrated engine platform, interesting.

http://www.aerojet.com/pix/capabilities/pyrojet_01.jpg

Click to expand...

Pyrodyne was a small company started by Fred Billig. Pyrodyne teamed with Aerojet for the design of this turbine based combined cycle propulsion system. When Fred passed away Pyrodyne ceased to exist. One former Pyrodyne principle formed GoHypersonic.

For details see:

Integration and Vehicle Performance Assessment of the Aerojet "TriJet" Combined-Cycle Engine

Adam Siebenhaar, Aerojet, Sacramento, CA; Thomas Bogar, The Boeing Company, St. Louis, MO
AIAA-2009-7420
16th AIAA/DLR/DGLR International Space Planes and Hypersonic Systems and Technologies Conference, Bremen, Germany, Oct. 19-22, 2009


The Advanced Combined-Cycle Integrated Inlet Test Program -Test Results

Timothy O'Brien, Aerojet, Sacramento, CA; David Davis, Aerojet, Sacramento, CA; Jesse Colville, Aerojet, Sacramento, CA
AIAA-2008-2637
15th AIAA International Space Planes and Hypersonic Systems and Technologies Conference, Dayton, Ohio, Apr. 28-1, 2008

http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2011/06/13/AW_06_13_2011_p22-332894.xml

Combines turbojet, ejector ramjet, and dual-mode ramjet.

Aerojet says concept is mature enough to fly as a demonstrator now. 40K lbf turbojet and total 160K lbf at takeoff.

Interesting indeed!

GeorgeA said:

http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2011/06/13/AW_06_13_2011_p22-332894.xml

Combines turbojet, ejector ramjet, and dual-mode ramjet.

Aerojet says concept is mature enough to fly as a demonstrator now. 40K lbf turbojet and total 160K lbf at takeoff.

Click to expand...

Ya gotta love Mel!

For a recent reference, see:

AIAA 2011-2397, Combined Cycle Propulsion:Aerojet Innovations for Practical Hypersonic Vehicles by Bulman and Siebenhaar, 17th AIAA International Space Planes and Hypersonic Systems and Technologies Conference, 11 - 14 April 2011, San Francisco, California.

More from Av Week:

TriJet - Aerojet's Hypersonic Three-in-One
Posted by Graham Warwick at 6/13/2011 11:13 AM CDT

A fly in the ointment for eventual development of a hypersonic reconnaissance/strike vehicle is the need for a propulsion system able to take the aircraft from a standing start to beyond Mach 6 and back to a runway landing.

Adherents to aircraft-like air-breathing operations have long favoured the turbine-based combined cycle (TBCC) concept, bringing together a high-Mach turbojet with a dual-mode ramjet/scramjet. But efforts to develop a high-Mach turbojet have failed, leaving designers with a problem - how to bridge the gap between the M2.5 maximum speed of today's turbine engines and the M3-3.5 take-over speed of a dual-mode ramjet (DMRJ) capable of accelerating the vehicle to M6-7.

Failure of the U.S. Air Force Research Laboratory's HiSTED program to produce a small turbojet capable of speeds up to Mach 4 helped doom DARPA's Mach 6 Blackswift. Now AFRL is proposing a follow-on TBCC demonstrator that would be built instead around an off-the-shelf fighter engine. That raises the issue of how to bridge the thrust gap.

As revealed in this week's issue of Aviation Week & Space Technology, Aerojet thinks it has a solution in the conceptually elegant, if aerothermomechanically mind-bending, TriJet TBCC engine. This bridges the gap between an off-the-shelf turbojet and a DMRJ by introducing a third engine - a rocket-augmented ejector ramjet (ERJ).

Essentially, the aircraft would take off on turbine power, then ignite the ejector ramjet to push through the transonic drag rise and accelerate to the take-over speed for the dual-mode ramjet. But the elegance of the concept is how the operating envelopes of the three engines overlap to provide seamless propulsion.

It starts at the inlet (above, in a twin TriJet installation), which feeds all three engines. While the dual-mode ramjet has an unobstructed flowpath, the turbojet and ejector ramjet are concealed behind doors that open and close depending on the phase of flight. From above, a view through the TriJet looks like this:

From zero airspeed to above Mach 1, the inlet doors to the turbine and ERJ engines would be fully open and both engines would be operating to produce enough thrust to punch through the transonic drag peak. Above M1, the doors to the turbine engine gradually close until, at M2.5, the turbojet is shut down, purged and concooned. The ERJ continues to provide thrust to M4+ before both inlet doors and nozzle flaps are closed.

Here's where it starts to get mind-bending. On its own, the DMRJ begins to provide thrust around M3. But it can be made to produce thrust down to M2.5 by operating it in "sustained aerodynamic choke" (SAC) mode, Aerojet says. Opening the nozzle flaps (above) causes the ERJ exhaust plume to "choke" the flow through the DRMJ. Upstream of the choke (see below), flow is subsonic, allowing the DMRJ nozzle to be used as a ramjet combustor. Pumping fuel into this much larger space allows both the ERJ and choked DMRJ to produce thrust from M2.5 to M4. Above that speed the ERJ nozzle flaps are closed and the DMRJ provides all the thrust.

The combined result of all this techno-trickery is a propulsion system that has sufficient thrust in all flight phases to accelerate the vehicle rapidly to its Mach 6+ hypersonic cruise, yet the flexibility to take off from a runway, refuel in flight, return to a powered landing and even execute a go-around. And Aerojet says the technology is mature enough to demonstrate in flight. Now all we need is the money - and the will.

Source and pictures:
Ares Blog - TriJet - Aerojet's Hypersonic Three-in-One

fightingirish said:

Source and pictures:
Ares Blog - TriJet - Aerojet's Hypersonic Three-in-One

Click to expand...

I feel bad for the structures guy who will have to deal with all the holes and weird shaping. I would have thought the gap between the two ERJ flaps would be a big problem but maybe not?

Since this was intended to gain from the shape of the fuselage, the limiting factor for the nozzle integration with the aft end of the fuselage is obvious. Could the equivalent be done with nested engines, as mentioned in early designs? If the turbine was at the center, wrapped by an ERJ, then wrapped with the DMRJ, then having a sliding cylinder behind an initial inlet shock cone would end up with something similar to a J58. The alternative is to reverse the wrapping order, keeping the DMRJ at the core, though that would require a hollow center jet engine, which is all new development, and puts an upper limit on diameter due to rotating machinery speed limits due to rotor strength. Actually, the turbine being off to the side is easier since there seems to be no intention of integrating it's nozzle with the ramjets. But the ERJ could have have been wrapped around the DMRJ making a sliding cylinder nozzle integration rather than a flap much easier?

Some subtleties that may not be apparent.

1. DMRJ is actually an RBCC. See the one small mention of rockets in the DMRJ, "Rockets are also embedded in the DMRJ".

2. The DMRJ also appears to have a physical, besides an aerodynamic choke. It's the "other engine, the ERJ" which has the doors but they open out into the DMRJ changing it's area distribution as well. So much for "the dual-mode ramjet has an unobstructed flowpath."

3. You now also need a whole other high pressure propellant system to supply the high-grape hydrogen peroxide. Tank(s), pumps(s) valves, etc. I'd like to see the power cycle for this proposed system.

could it be render of Blackswift's reincarnation - HSRFRV? just curious

Could one of the mods change the title of this thread to "Aerojet and Pyrodyne - Pyrojet Turbine Based Combined Cycle".

It's not correct as it is currently stated, and doesn't do service to the late Fred Billig one of the
big promoters of scramjet and if I recall correctly, the man who gave supersonic combustion
the name "scramjet".