Experimental Investigation of a Three-Dimensional Scramjet Engine at Mach 12

Wise, Dylan J.; Smart, Michael K.

doi:10.2514/6.2015-3650

Cited by 9 publications

(20 citation statements)

References 14 publications

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“…Maintaining constant mass-flow requires Hydrogen storage under pressure to maintain a positive pressure gradient into the combustion chamber. A system of fast-actuating valves controlled by solenoids is how the M12 REST experiments controlled fuel injection testing [5]. Strut injectors are characterized by their obstruction to the flow direction and oblique shockwave generation (Figure 4), injecting fuel consistent with the direction of the entry flow.…”

Section: Injector Geometry and Arrangementmentioning

confidence: 99%

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Modeling of Supersonic Combustion Systems for Sustained Hypersonic Flight

Neill

Pesiridis²

2017

Energies

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Through Computational Fluid Dynamics and validation, an optimal scramjet combustor has been designed based on twin-strut Hydrogen injection to sustain flight at a desired speed of Mach 8. An investigation undertaken into the efficacy of supersonic combustion through various means of injection saw promising results for Hydrogen-based systems, whereby strut-style injectors were selected over transverse injectors based on their pressure recovery performance and combustive efficiency. The final configuration of twin-strut injectors provided robust combustion and a stable region of net thrust (1873 kN) in the nozzle. Using fixed combustor inlet parameters and injection equivalence ratio, the finalized injection method advanced to the early stages of two-dimensional (2-D) and three-dimensional (3-D) scramjet engine integration. The overall investigation provided a feasible supersonic combustion system, such that Mach 8 sustained cruise could be achieved by the aircraft concept in a computational design domain.

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Section: Injector Geometry and Arrangementmentioning

confidence: 99%

Section: Injector Geometry and Arrangementmentioning

confidence: 99%

Modeling of Supersonic Combustion Systems for Sustained Hypersonic Flight

Neill

Pesiridis²

2017

Energies

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“…The simulated flow path is a geometric half scale of the original engine flow path, designed for Mach 12 flight at 50 kPa dynamic pressure. The half scale model examined here was the largest engine size which could be experimentally validated in (Wise and Smart, 2015), and has a total length of approximately 1439 mm including the 500 mm forebody (not pictured in Fig. 5.2), which is characteristic of the vehicle underside when integrated to the airframe.…”

Section: Methodsmentioning

confidence: 99%

“…The 282 mm long combustor begins approximately 530.9 mm downstream of the leading edge, and is inclined at 6°, serving to realign the flow with the nominal flight direction (the forebody is assumed to be at a 6°angle-of-attack in flight). The combustor is joined to the engine isolator via a 1.25 mm high, circumferential backward-facing step, originally included to facilitate a ring of boundary layer fuel injectors (Wise and Smart, 2015). The combustor consists of an elliptical 161 mm constant crosssection segment, followed by a diverging segment with a constant divergence angle of 1.6°for 121 mm to achieve a 2:1 area ratio to the throat.…”

Section: Methodsmentioning

confidence: 99%

“…The notched cowl and sidewall compression surfaces further permit the inlet to operate efficiently across a range of Mach numbers (Smart, 1999;Gruhn and Gülhan, 2011;Doherty et al, 2012a). With this noted, the REST engine is examined here as a case-study since it is representative of practical inlet designs, and both Mach 8 (M8REST) (Turner and Smart, 2010;Chan et al, 2014;Denman et al, 2016;Denman et al, 2017) and Mach 12 (M12REST) Doherty et al, 2012a;Landsberg et al, 2014;Barth et al, 2015a;Wise and Smart, 2015) models have been subjected to experimental and numerical studies. Airframe-integrated engines typically ingest thick boundary layers, developed over the vehicle forebody and inlet sidewalls (Henry and Anderson, 1973).…”

Section: Introductionmentioning

confidence: 99%

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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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Performance of high mach number scramjets - Tunnel vs flight

et al. 2018

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While typically analysed through ground-based impulse facilities, scramjets experience significant heating loads in flight, raising engine wall temperatures and the fuel used to cool them beyond standard laboratory conditions. Hence, the present work numerically compares an access-to-space scramjet's performance at both these conditions. The Mach 12 Rectangular-to-Elliptical Shape-Transitioning scramjet flow path is examined via three-dimensional and chemically reacting Reynolds-averaged Navier-Stokes solutions. Flight operation is modelled through 800 K and 1800 K inlet and combustor walls respectively, while fuel is injected at both inlet-and combustor-based stations at 1000 K stagnation temperature. Room temperature walls and fuel plena model shock tunnel conditions. Mixing and combustion performance indicates that while flight conditions promote rapid mixing, high combustor temperatures inhibit the completion of reaction pathways, with reactant dissociation reducing chemical heat release by 16%. However, the heated walls in flight ensured 28% less energy was absorbed by the walls. While inlet fuel injection promotes robust burning of combustor-injected fuel, premature ignition upon the inlet in flight suggests these injectors should be moved further downstream. Coupled with counteracting differences in heat release and loss to the walls, the optimal engine design for flight may differ considerably from that which gives the best performance in the tunnel.

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Experimental Investigation of a Three-Dimensional Scramjet Engine at Mach 12

Cited by 9 publications

References 14 publications

Modeling of Supersonic Combustion Systems for Sustained Hypersonic Flight

Modeling of Supersonic Combustion Systems for Sustained Hypersonic Flight

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

Performance of high mach number scramjets - Tunnel vs flight

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