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Experiments on Supersonic and Superdetonative Combustion at ISL’s Ram Accelerator RAMAC 30

  • Friedrich SeilerEmail author
  • Günter Smeets
  • Gunther Patz
  • Julio Srulijes
  • Gilbert Mathieu
  • Berthold Sauerwein
  • Jean-Luc Striby
Chapter
Part of the Shock Wave Science and Technology Reference Library book series (SHOCKWAVES, volume 10)

Abstract

The acceleration of a projectile flying by the self-synchronized ignition of an explosive gas in a 38-mm-tube, the “Ram accelerator”, was first successfully developed and tested by Hertzberg et al. [10]. From this time on, this accelerator concept has generated considerable interest in various countries, particularly in the USA, Israel, Japan, Korea and France. The ISL in France performed experiments at superdetonative flight speeds in a 30 mm-caliber ram accelerator, called RAMAC 30 which are concisely described in this chapter. At the same time, [5] operated also at ISL the RAMAC 90 in the subdetonative velocity regime. In RAMAC 30 a conventional gun, as pre-accelerator, injected a ram-projectile into a single stage ram tube filled with hydrogen, methane or ethylene based gas mixtures. A ram-tube equipped with rails for guiding smooth cylindrical projectiles was tested as accelerator: the rail tube version I with four inner rails (Sect. 2.2) and the rail tube version II with five inner rails (Sect. 2.3). The smooth bore technique was tested too (Sect. 3). The projectile was fired into the ram-tube with superdetonative speed, relative to the gas mixture, so that the combustion stabilized on the projectile body from the beginning on. The gas combustion causes a temperature rise followed by a gas pressure increase at practically constant gas density propelling the ram-projectile. The heat transfer from gas to projectile causes the latter’s surface temperature to increase. This can lead to melting processes followed by ablation of surface material which is obviously undesirable. Therefore, a prediction of the heat flux from gas to projectile surface becomes necessary and for this purpose a boundary layer and ablation model was developed by which the heating of the projectile and its melting ablation at nose, fins and body can be estimated (Sect. 4). Damage of projectile was observed on X-ray pictures, especially of the fins, probably by melting and burning when magnesium, aluminum or titanium alloys were used. Steel projectiles can endure the ram acceleration cycle, but the projectile mass is too large to achieve sufficient acceleration.

Keywords

Projectile Velocity Flow Mach Number Projectile Mass Scramjet Engine Oblique Detonation Wave 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  • Friedrich Seiler
    • 2
    Email author
  • Günter Smeets
    • 2
  • Gunther Patz
    • 2
  • Julio Srulijes
    • 2
  • Gilbert Mathieu
    • 2
  • Berthold Sauerwein
    • 1
  • Jean-Luc Striby
    • 1
  1. 1.French-German Research Institute of Saint-Louis (ISL)Saint LouisFrance
  2. 2.Retired from ISLSaint-LouisFrance

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