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MAE 4261: AIR-BREATHING ENGINES Ramjet Analysis Overview Mechanical and Aerospace Engineering Department Florida Institute of Technology D. R. Kirk.

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Presentation on theme: "MAE 4261: AIR-BREATHING ENGINES Ramjet Analysis Overview Mechanical and Aerospace Engineering Department Florida Institute of Technology D. R. Kirk."— Presentation transcript:

1 MAE 4261: AIR-BREATHING ENGINES Ramjet Analysis Overview Mechanical and Aerospace Engineering Department Florida Institute of Technology D. R. Kirk

2 RAMJET BASIC OPERATION Ramjet has no moving parts Achieves compression of intake air by forward speed of vehicle Air entering the intake of a supersonic aircraft is slowed by aerodynamic diffusion created by the inlet and diffuser to low velocities Expansion of hot gases after fuel injection and combustion accelerates exhaust air to a velocity higher than that at inlet and creates positive thrust Fuel injectors

3 KEY RESULTS: RAMJET Begin with non-dimensional thrust equation, or specific thrust Ratio of exit to inlet velocity expressed as ratio of Mach numbers and static temperatures. Recall that for a Ramjet M e =M 0 Ramjet specific thrust depends on temperature ratio across burner,  b –Compare with H&P EQ. (5.27) Energy balance across burner Expression for fuel flow rate for certain temperature rise of incoming mass flow and fuel energy, h Useful propulsion metrics –Specific impulse, thrust specific fuel consumption, and overall efficiency

4 WHAT DID WE LEARN? Figure 5.9 from Hill and Peterson: Ramjet performance parameters vs. flight Mach number Specific thrust has peak value for set T max and Ta Specific thrust increases as maximum allowable combustor exit temperature increases Specific fuel consumption decreases with increasing flight Mach number

5 WHAT DID WE LEARN? Figure 5.10 from Hill and Peterson: Ramjet performance parameters vs. flight Mach number Specific thrust has peak value for set T max and Ta. Peak is around Mach 2.5 Propulsive, thermal and overall efficiencies increase continually with increasing Flight Mach number

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7 RAMJET POWERED MISSILES Boeing/MARC CIM-10A BOMARC A Surface-to-Air Missile Aerojet General LR59-AG-13 liquid rocket; Two Marquardt RJ43-MA-3 ramjets

8 SOME DETAILS ON BOMARC MISSILE Flight testing started in 1952 –First launch from Cape Canaveral in September of 1952 Bomarc A became fully operational in 1959 –Numerous deployments from Florida to Maine defended U.S. eastern sea board Booster on Bomarc A was source of problems –Fuel was too corrosive to store in missile, so fueling took place immediately before launch (increasing time to launch) –Fueling process was also quite hazardous, involving three steps (white fuming nitric acid, analine-furfuryl alcohol, and kerosene) New model that utilizes a solid fuel booster –Bomarc B became operational in 1961, and featured a safer solid fuel booster and more powerful sustainers Boeing built 700 Bomarc missiles between 1957 and 1964, and Bomarc in active service until 1972 Length 46 ft. 9 in, Wingspan 18 ft. 2 in, Speed Mach 2.8, Range 250 miles, Ceiling 65,000 ft, Cost: $ 1,154,000 per shot Propulsion: –One Aerojet General LR59-AG-13 liquid rocket –Two Marquardt RJ43-MA-3 ramjets

9 MISS BOMARC

10 HyFly RAMJET CONCEPT Hypersonic Flight Demonstration Program Cruise Flight Mach Number ~ 6 Range 600 nm (1111 km)

11 HyFly RAMJET CONCEPT HyFly program was initiated in 2002 by DARPA (Defense Advanced Research Projects Agency) and U.S. Navy's ONR (Office of Naval Research) to develop and test a demonstrator for a hypersonic Mach 6+ ramjet-powered cruise missile Prime contractor for HyFly missile is Boeing, Aerojet builds sustainer engine Air-launched from F-15E and accelerated to ramjet ignition speed by solid-propellant rocket booster Engine runs on conventional liquid hydrocarbon fuel (JP-10) –Much easier to handle than cryogenic fuels (LH 2 ) used on other hypersonic scramjet vehicles Sustainer engine of HyFly is a dual-combustion ramjet (DCR) (very complex) –Two different air inlet systems Operate as a "conventional" ramjet with subsonic combustion Operate at hypersonic speeds as a scramjet First scramjet engine (hybrid or otherwise) to demonstrate operability with LH 2 fuel

12 RAMJET POWERED MISSILES Orbital Sciences GQM-163 Coyote: Ducted rocket/ramjet engine, Flight speed up to Mach 2.8 at seal-level Hercules MK 70 rocket booster

13 RUSSIA'S P-700 GRANIT LONG-RANGE ANTI-SHIP MISSILE (SS-N-19 ‘SHIPWRECK’) Launched by two solid-fuel boosters before sustained flight with ramjet Maximum speed believed ~ Mach 2.25 Range is estimated at 550 to 625 km Weight: 7,000 kg, Length: 10 m, Diameter: 0.85 m Altitude up to 65,000 ft

14 J58 SR-71 ENGINE: RAMJET/TURBOJET HYBRID

15 MAIN IDEA: TURBO-RAMJET

16 J58 TURBO-RAMJET

17 RAMJET VS. SCRAMJET Large temp rise associated with deceleration from high speed to M~0.3 for combustion Solution for increased flight speed: decelerate to ‘lower’ supersonic speeds in combustor Combustion very difficult (flame support) in a high speed flow Vehicle cooling requirements become very challenging

18 X-51

19 SUMMARY Ramjet develops no static thrust Relies on ‘ram’ compression of air –Requires high speed flight Performance depends on increase in stagnation temperature across burner (combustor) Efficiencies (thermal, propulsive, and overall) increase with increasing flight Mach number Next step: We desire an engine that develops static thrust –Put in a device to mechanically compress air (compressor) –Put in a device to power compressor (turbine) Solution: Turbojet engine

20 INTERSTELLAR RAMJET: ‘HYDROGEN-BREATHING ENGINE’ In this concept, interstellar hydrogen is scooped to provide propellant mass –Hydrogen is ionized and then collected by an electromagnetic field Onset of ramjet operation is at a velocity of about 4% speed of light Typically, interstellar ramjets are very large systems A ramjet sized for a 45-year manned mission to Alpha Centauri would have a ram intake 650 km in diameter and weigh 3000 metric tons including payload


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