Experimental flow visualization for a large-scale ram accelerator

Kruczynski, D.; Liberatore, Federico; Nusca, Michael J.

doi:10.2514/3.24013

Cited by 11 publications

(2 citation statements)

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“…Velocities of 2700 m/s have been achieved, and projectiles as massive as 5 kg (in a 120-mm-bore launch tube 11 ) have been successfully accelerated. Unique facilities, such as a two-dimensional ram accelerator with a wedge-shaped projectile to facilitate flow visualization, 12 have also been successfully operated.…”

Section: Introductionmentioning

confidence: 99%

Ram Accelerators: Outstanding Issues and New Directions

Higgins

2006

Journal of Propulsion and Power

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An assessment of the key issues affecting the thrust and maximum velocities that can be obtained in ram accelerators is presented. The regimes of ram accelerator operation (subdetonative and superdetonative) are discussed, and simple models for thrust are compared to experimental results and found to be satisfactory. The phenomena that are responsible for the operating limits of these modes of operation are explored, and potential solutions for overcoming these limits are discussed. In particular, the possibility that flow separation may cause unstarts in both the subdetonative and superdetonative ram accelerator is shown to explain qualitatively the experimentally observed limits. A potential remedy to the unstart problem that involves modifying the geometry of the ram accelerator tube is presented. The role of the projectile material, which may react with the oxidizing environment of the propellant, also has a significant effect on superdetonative operation. Techniques to address this problem are outlined. Other novel concepts, such as the use of an explosive-lined launch tube and the laser-driven ram accelerator, are discussed as well. Nomenclature A= area A R = area ratio (tube area to throat area)= Mach angle q = heat release ρ = density τ = viscous shear stress χ = inert gas dilution Subscripts s = flow condition at boundary-layer separation point 1 = flow conditions approaching projectile 2 = flow conditions at projectile throat 6 = flow condition exiting projectile control volume in thermally choked mode

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Section: Introductionmentioning

confidence: 99%

Ram Accelerators: Outstanding Issues and New Directions

Higgins

2006

Journal of Propulsion and Power

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“…Numerous experimental investigations of the subdetonative velocity regime have been carried out at Mach numbers ranging from 2.5 to 5 [4][5][6][7][8]. The supersonic incoming flow is compressed by reflected shock waves in the contraction area of the conical forebody and rendered subsonic by a normal shock wave system on the tapered aftbody of the projectile.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of gaseous reactive flow over a ram accelerator projectile in subdetonative velocity regime

Bengherbia

Yao

Bauer

et al. 2011

Eur. Phys. J. Appl. Phys.

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Abstract. Computational fluid dynamics solutions of the Reynolds Averaged Navier-Stokes equations have been used to numerically predict the thrust in the thermally choked ram accelerator propulsive mode. Studies were focused on a projectile operating in a 38-mm-diameter ram accelerator tube loaded with premixed propellant gas; methane/oxygen/nitrogen at 5.15 MPa fill pressure. Simulations were carried out for a series of incoming velocities. The shear-stress transport turbulence model (SST) and the eddy dissipation combustion model (EDM) with five-step reaction mechanism were used to simulate the fully turbulent reactive flow field around the projectile. The predicted projectile thrust-velocity agreed well a with the experimental measurements, in addition, the CFD predicted pressure variation and magnitude along projectile axial direction also agreed well with the test data. The present investigation reveals some key features of the shock system around the projectile, which are important in determining the characteristics of the thermally choked propulsive mode. These findings are useful in understanding the characteristics of high speed turbulent combustion process in the ram accelerator.

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