Measurements of cellular structure in spray detonation

Conference · Tue Oct 01 00:00:00 EDT 1991

OSTI ID:7101873

Papavassiliou, J; Makris, A; Knystautas, R; Lee, J H ^[1]; Westbrook, C K; Pitz, W J ^[2]

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1. McGill Univ., Montreal, PQ (Canada). Dept. of Mechanical Engineering
2. Lawrence Livermore National Lab., CA (United States)

The cellular structure of heterogeneous detonations in a low vapor pressure fuel (decane) droplet mixture with oxygen and oxygen-nitrogen was studied in the present investigation. The aerosol was generated by an ultrasonic nebulizer and the fuel concentration of the mixture was regulated by monitoring the volume flow rate of oxygen and nitrogen through the nebulizer. The vertical detonation tube is 64 mm in diameter and 3 m long and ignition was by a powerful spark (120 joules stored energy) or a high explosive detonator. Velocity was measured with ionization probes, pressure by a PCB piezoelectric transducer and cell size by a smoked metallic foil inserted into the top end or centre of the detonation tube. The initial pressure of all the experiments was 1 atmosphere. In order to compare the time scales associated with the physical processes of droplet breakup, heat transfer, evaporation, and mixing, experiments were also carried out in the tube heated to 100{degree}C and 185{degree}C, using electrical heating tape, to ensure a homogeneous gas phase mixture of decane-oxygen-nitrogen. Comparison of the cell size for the same mixture in the cold and the heated tube permits one to separate the time scales associated with the physical processes and the chemical kinetic rate processes. The results from the heated tube for the homogeneous vapor phase decane detonations are similar to those for the common gaseous fuels in the alkane group (i.e. ethane, propane, butane). Corresponding results for the heterogeneous case (cold tube) of aerosol decane detonation indicate that the cell size is larger by a factor of about 2, for the present case of 5 {mu}m particle size. The measurements of cellular structure obtained experimentally have been compared to the computed results determined using the ZND chemical kinetic detonation model.

• Research Organization: Lawrence Livermore National Lab., CA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7101873
• Report Number(s): UCRL-JC-108710; CONF-9107160-3; ON: DE92019580
• Resource Relation: Conference: 13. international colloquium on dynamics of explosives and reactive systems, Nagoya (Japan), 28 Jul - 31 Aug 1991
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
DECANE
DETONATIONS
AEROSOLS
COMBUSTION KINETICS
ELECTRIC SPARKS
FLOW RATE
MIXTURES
NITROGEN
OXYGEN
TUBES
VELOCITY
ALKANES
CHEMICAL REACTION KINETICS
COLLOIDS
DISPERSIONS
ELECTRIC DISCHARGES
ELEMENTS
HYDROCARBONS
KINETICS
NONMETALS
ORGANIC COMPOUNDS
REACTION KINETICS
SOLS
330100* - Internal Combustion Engines
400800 - Combustion
Pyrolysis
& High-Temperature Chemistry