Inlet Starting of High-Contraction Axisymmetric Scramjets

Ogawa, H.; Grainger, Alex; Boyce, Russell

doi:10.2514/6.2009-7401

Cited by 9 publications

(12 citation statements)

References 9 publications

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“…For the scenario that is presented in this paper, the RCS is not activated at point (6). The RCS is activated on the descent trajectory at an altitude of 160km.…”

Section: Fig 2 Scramspace Trajectory Mission Profilementioning

confidence: 99%

“…The starting door covers shield the starting door mechanism from the external flow during ascent6. For the standard mission, the RCS is activated as soon as soon as the ejections are complete (6), and the RCS manoeuvres take place during the entire exo-atmospheric portion of the flight, using nitrogen cold gas thrusters. The primary scramjet experiment takes place on the descent, between 32 and 27km altitude (8 & 9), where a changes in axial force will be measured whilst pulsing fuel on and off.…”

Section: Fig 1 Scramspace Flight Experimentsmentioning

confidence: 99%

“…After separation, the nosecone and starting door covers are ejected with compressed nitrogen (6). The starting door covers shield the starting door mechanism from the external flow during ascent6.…”

Section: Fig 1 Scramspace Flight Experimentsmentioning

confidence: 99%

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An Alternative Attitude Control Strategy for SCRAMSPACE 1 Experiment

Banerjee

Creagh

Boyce

2014

AIAA Guidance, Navigation, and Control Conference

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The current reaction control strategy for SCRAMSPACE 1 involves an exo-atmospheric reorientation using attitude and rate feedback from the Inertial Navigation System. An alternative design methodology of an attitude control system is presented that only uses rate feedback. This eliminates the need for an attitude determination system altogether. This methodology is designed to re-orient the hypersonic experimental vehicle SCRAMSPACE 1 by using rate damping and natural aerodynamic moments. It is desired that the re-orientation produces a 2.5 degrees angle of attack at 32km altitude on the decent trajectory. This angle of attack is necessary in order to test the scramjet at Mach 8. The re-entry rate damping is initialized at an altitude of 55km on the descent trajectory. The worst case scenario angle of attack of 150 degrees is taken as the initial conditions at 200km altitude. For the worst case scenario, thrusters of size 10N, 15N, 20N, 25N and 30N are able to acquire the desired angle of attack. The final angles of attack for all the aforementioned thruster sizes are less than 1 deg. The mean of the angle of attack during the experimental window is under 0.5 degrees for all tested cases of thruster force, initial spin rate and initial angle of attack. However, when a sensible fuel restriction of 5kg is placed, the recommended thruster size is 20N. Nomenclature = body coordinates 1 , 2 , 3 = body coordinate axes , , = roll, pitch and yaw principle moments of inertial, kgm 2 = component xy of moment of inertia matrix, kgm 2 = specific impulse, sec , = autopilot feedback gains for roll angle and roll rate , , = roll, pitch, yaw moment requests about body coordinate axes, Nm , , = roll, pitch, yaw rate, rad/s 1, 2, 3, 4 = thruster force, N. = nominal thruster force, N = angle of attack, deg = initial angle of attack, deg !, ", # = roll, pitch, yaw angles, rad 1$ = 1 standard deviation (Gaussian distribution)

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“…For the scenario that is presented in this paper, the RCS is not activated at point (6). The RCS is activated on the descent trajectory at an altitude of 160km.…”

Section: Fig 2 Scramspace Trajectory Mission Profilementioning

confidence: 99%

Section: Fig 1 Scramspace Flight Experimentsmentioning

confidence: 99%

See 1 more Smart Citation

An Alternative Attitude Control Strategy for SCRAMSPACE 1 Experiment

Banerjee

Creagh

Boyce

2014

AIAA Guidance, Navigation, and Control Conference

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“…1 1 . The resultant subsonic conditions are detrimental towards proper engine operation 2,3,4 and as such, this flow regime is to be avoided.…”

Section: Introductionmentioning

confidence: 99%

Investigation into the Flow Physics of Hypersonic Variable Geometry Inlet Starting

Grainger

Brieschenk

Boyce

et al. 2014

19th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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A coupled numerical-experimental investigation studying the applicability of a Sliding Doors variable geometry inlet starting mechanism for a 2D SCRAMjet inlet at Mach 6 has been undertaken. Door opening speeds ranging from 3 to 20ms repeatedly produced started inlet conditions when tested within the TUSQ Low-Enthalpy Wind Tunnel. Transient flow during door retraction was captured both quantitatively and qualitatively via surface pressure measurements and Schlieren visualization techniques. A blunt wedge protruding upstream into the combustor from the rear of the model was also installed, simulating a large pressure rise within the combustor at the centerline. Inlet unstart was encountered for a wedge position protruding 7mm upstream into the combustor, with door opening speeds as low as approximately 1ms were seen to have no visible effect on inlet startability. A viscous, transient, time accurate numerical investigation was conducted, recreating the experimental conditions by solving the Reynolds-Averaged Navier-Stokes equations. These simulations provide insight into pockets of the flowfield for which optical access was not available, as well as also allowing faster door opening speeds to be employed which were not mechanically possible in the tunnel. It was found that even extreme door opening speeds of 0.1ms were not able to start the more aggressive forward wedge positions. Interactions between shock structures around the leading edge of the wedge and the boundary layer at the rear of the combustor were seen to supersede the positive effects of employing unsteady effects. NomenclatureA e = inlet exit cross-sectional area [m 2 ] A i = inlet entrance cross-sectional area [m 2 ] A * /A t = inlet throat cross-sectional area [m 2 ] M = Mach number ∞ = freestream conditions t = time [s] x = horizontal Cartesian coordinate [m] r = radius [m] q = dynamic pressure [Pa] T = temperature [K] P = pressure [Pa] CR = contraction ratio

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“…After detecting the unstart, the X-51A oriented itself to optimize engine start conditions but restart attempts proved unsuccessful and the vehicle destroyed soon. Therefore, in recent years a number of numerical and experimental studies were performed to control the inlet unstart [4][5][6][7] and to improve the restart capability of the inlet [8][9][10][11]. However, most of these control ideas are hard to achieve in practice.…”

Section: Introductionmentioning

confidence: 99%

Investigation of a Movable Slot-Plate Control Method for Hypersonic Inlet Unstart Caused by Downstream Mass-Flow Choking

Zhang¹,

Tan²,

Huanxian³

2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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Violent oscillation caused by unstart in a hypersonic inlet will always bring fatal damages to the flight control and structural safety of the vehicle. A new control method for the hypersonic inlet unstart caused by downstream mass-flow choking based on a movable slotplate is brought forward and investigated by computational method. First, the start and unstart flows of the two-dimensional rectangular hypersonic inlet are studied at a freestream Mach number of 4.92. The results show that the captured mass flow rate is 3.005kg/s at the started mode and the dominant frequency of oscillations is approximately 351Hz at the unstarted mode with TR=58%.Then, the movable slot-plate starts to open to let air flow spill, and when the mass flow rate of spilled reaches 1.447kg/s, the oscillation of the unstard flow vanishes. However the slot-plate has no effect on improving the inlet restart capability.

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Inlet Starting of High-Contraction Axisymmetric Scramjets

Cited by 9 publications

References 9 publications

An Alternative Attitude Control Strategy for SCRAMSPACE 1 Experiment

An Alternative Attitude Control Strategy for SCRAMSPACE 1 Experiment

Investigation into the Flow Physics of Hypersonic Variable Geometry Inlet Starting

Investigation of a Movable Slot-Plate Control Method for Hypersonic Inlet Unstart Caused by Downstream Mass-Flow Choking

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