Domain of the Scramjet

Townend, L. H.

doi:10.2514/2.5865

Cited by 28 publications

(4 citation statements)

References 20 publications

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“…This is due mainly to effects associated with the high gas temperatures attained in slowing the freestream to subsonic speeds for combustion. For higher Mach number flight, the supersonic combustion ramjet or scramjet has shown considerable promise [2]. In a scramjet, the problems that plague the conventional ramjet at higher Mach numbers are avoided by maintaining a supersonic flow throughout the engine.…”

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confidence: 99%

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Application of Inlet Injection to a Three-Dimensional Scramjet at Mach 8

Turner

Smart

2010

AIAA Journal

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An investigation of inlet injection in a scramjet having a three-dimensional inlet and an elliptical combustion was undertaken. Experiments were conducted using a test flow simulating a Mach 8.1 flight condition with an altitude of 32 km. The objective was to determine the feasibility of reducing the combustion-chamber length by injection of hydrogen fuel in the inlet. The study involved a self-starting three-dimensional inlet with an overall geometric contraction ratio of 5.80, of which 2.08 was internal. The fuel was injected through multiple portholes in the forward portion of the inlet to allow significant mixing upstream of the combustion chamber. The divergent elliptical combustion chamber had a length sized for fuel ignition and combustion only and used a fluid-dynamic ignition scheme requiring no physical obstructions to the flowpath. Results indicated that inlet injection produced robust combustion at good combustion efficiency over a large fueling range up to an equivalence ratio of 0.92. A further key result was that no evidence of combustion was observed in the inlet. These experiments suggest that fuel injection in the inlet is a promising concept for higher-speed scramjet applications.

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confidence: 99%

“…IGH-SPEED flight within the atmosphere has applicability to transport, defense, and space access [1,2]. To date, the two most successful propulsion systems are the rocket and the conventional ramjet.…”

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confidence: 99%

Application of Inlet Injection to a Three-Dimensional Scramjet at Mach 8

Turner

Smart

2010

AIAA Journal

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Section: Declaration By Authormentioning

confidence: 99%

“…-Leo H. Townend (2001) It follows that in addition to efficiency restrictions, ramjets simply cannot be manufactured to withstand the pressures and heating loads experienced during hypersonic flight. To alleviate these issues, Townend (2001) recommends an altered engine type: the supersonic combustion ramjet (scramjet), which performs as the name indicates. With the flow only decelerated marginally and remaining supersonic throughout the engine, air pressure and temperature conditions appropriate for combustion are obtained while circumventing the structural and gas-dynamic issues previously mentioned.…”

Section: Declaration By Authormentioning

confidence: 99%

Improving performance of high Mach number scramjets: fuelling strategies and combustor design

Landsberg¹

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With prospective flight speeds exceeding Mach 12, airbreathing scramjets, incorporated in hybrid satellite launch vehicles, offer efficiency and operability benefits when compared to rocket-based systems. By capturing atmospheric air, the scramjet second stage negates the requirement for onboard oxidisers. Addressing the small satellite niche market, these hybrid systems provide a cost-effective solution to launching such payloads to orbit. At hypersonic speeds, however, conventional wing-mounted engine nacelles are not viable; the scramjet must be integrated to the airframe. Hence, the flight-candidate, Mach 12 Rectangular-to-Elliptical Shape-Transitioning (M12REST) scramjet blends a rectangular capture area (permitting parallel mounting of engine modules to the planar vehicle underside), with a structurally efficient elliptical combustor. As access-to-space scramjets suffer immense heating loads, and engine airflow residence times approach air-fuel reaction timescales, hydrogen fuel is utilised for its exceptional cooling capacity and rapid ignition characteristics. However, efficient fuelling techniques are required to avoid crippling the engine's performance through conservative combustor lengths. This thesis numerically and experimentally investigated whether the performance of such an airframe-integrated scramjet can be sufficiently enhanced through customisation of fuel injection and combustor geometry to achieve net thrust at Mach 12. Three-dimensional, chemically reacting Reynolds-averaged Navier-Stokes solutions enabled numerical analysis, while experimental validation was performed within The University of Queensland's, T4 Stalker Tube.Preliminary work investigated cascaded fuel injectors, targeting mixing and penetration improvements. Two streamwise-aligned jets were employed, with the upstream injector half the diameter of the rear, while the distance between each was varied. The upstream jet induced a low dynamic pressure region in its wake, shielding the downstream jet from the hypersonic crossflow. The leeward jet benefits from an increased local jet-to-freestream momentum ratio, while its larger diameter increases absolute penetration. Examining performance at M12REST mean combustor entrance conditions, unique optimal injector spacings existed for each performance metric, displaying improved penetration, spread, and mixing across the range of flight Mach numbers examined (6 ≤ M ≤ 12). However, jet-to-jet spacings of 4-6 total jet diameters displayed universal performance enhancements over single fuel jets. With penetration improvements of 30-40%, and mixing improvements of 40-70%, the simple fixed geometry, passive technique is ideal for use within an accelerating access-to-space scramjet.While cascaded injectors improved performance within uniform flows, the flows ingested by airframe-integrated scramjets are far less homogeneous. Non-uniform compression fields combine with thick boundary layers developed over the vehicle forebody to deliver density stratified flow to the combustor. This thesis ...

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Combustion in Supersonic Flows and Scramjet Combustion Simulation

Sabelnikov

Власенко²

2017

Energy, Environment, and Sustainability

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Domain of the Scramjet

Cited by 28 publications

References 20 publications

Application of Inlet Injection to a Three-Dimensional Scramjet at Mach 8

Application of Inlet Injection to a Three-Dimensional Scramjet at Mach 8

Improving performance of high Mach number scramjets: fuelling strategies and combustor design

Combustion in Supersonic Flows and Scramjet Combustion Simulation

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