Detonation Physics Laboratory
This laboratory is designed to explore the physics of detonations in gases.
There are two main detonation tubes or channels permanently set up in this laboratory.
The original detonation tube facility was been designed and constructed by Raza Akbar,
Pavel Svitek, and Mike Kaneshige from 1993-1996. New flanges were designed by Tony Chao
with help from Patrick Hung. In 2000 Tony designed a heating system, and Florian
Pintgen installed and made this operational. Florian moved the data acquisition
system from Sun Unix to Linux in 2003. A compansion narrow channel facility was
designed and built by Jo Austin in 2002 with help from Marty Grunthaner. This
facility is 18 X 150 mm and has a novel planar initiation developed by Marty
and Scott Jackson.
The GALCIT detonation tube is 7.3 m (24-ft) long, 280 mm (11-in.) inner
diameter and constructed of 3 cast stainless steel (304) segments joined
together by flanges and high-strength fasteners. The tube is equipped with
a gas control system to precisely create test mixtures of fuel, oxidizer and
diluents; a gas mixer system; a vacuum system; instrumentation and data
acquisition systems. Gas composition is determined by the method of partial
A short slug of oxygen-acetylene mixture is injected just prior to
initiation as booster charge. The driver is initiated by an exploding wire
created by discharging a capacitor through a copper wire. The driver
produces a blast wave with an peak amplitude of about 0.4 MPa (60 psig) at
the first pressure transducer, sufficient to initiate mixtures with cell
widths up to 400 mm.
Strain gauges and
accelerometers are used to measure the tube motion and piezo-electric
pressure transducers are used for detonation timing. Data are recorded on
multichannel CAMAC-based digitizers and high-speed (1 GHz) digital
oscilloscopes. A network of Unix-based workstations and PCs is used to
acquire and analyze the data.
Detonation cell width is measured by inserting into the tube
sooted foils 3 ft x 4 ft rolled
into a cylindrical shape and riveted to a stiffening ring.
For flow visualization studies, a cookie cutter is used to attach a
6-in by 6-in square section optical test section to the round tube and
windows are directly attached to the narrow channel.
High-speed (up to 1 MFPS and ns exposure times) framing,
streak and still cameras are available for conventional photography and
holographic interferometry. An excimer/dye laser and gated UV-sensitive
CCD camera are available for PLIF measurements. A 1-m VIS-UV spectrometer
is available for low resolution spectrum recording.
Studies carried out in this laborotory include:
Explosion Dynamics Laboratory
This laboratory is designed to examine issues related to flammability, flame
propagation and deflagration-to-detonation transition. Four explosion vessels
are available with volumes between 1 and 1200 liters, capable of containing
pressures up to 100 atm. High-speed data acquisition systems, schlieren
systems with video and rotating drum cameras, and instrumentation for
pressure and temperature measurement are provided for these test systems.
A flexible gas supply system and precision pressure measurements are used to
create mixtures of various fuel-air types. Gas chromatography
measurements are also available. A network of Unix-based workstations and PCs
is used to acquire and analyze the data. A two-component
laser-doppler-velocimeter is set up for measuring flow velocities during
- Measurement of detonation structure (cell width) in Jet A, JP-10
and in HC fuel blends.
- Correlation of detonation cell widths with detailed chemical reaction
- Measurements and Models of detonation diffraction openings and tubes.
- Investigation of flexural waves created in shock tubes and detonation tubes.
- Measurement of detonation front structure using high-speed imaging and OH PLIF
- Spectroscopic investigation of detonations
- Behavior of detonations in narrow channels and with acoustic absorbing walls
- Photochemical initiation of detonation
Studies carried out in this laboratory include:
Blast Wave and Dynamic Fracture Laboratory
This laboratory is designed to examine issues related to high explosives
and propulsion. A test cell rated to 25 g of high explosive and a test
chambers with up to 100 g high explosive capacity are available.
Detonation tubes and a ballistic pendulum are available to measure impulse,
for pulse detonation engine applications. A special facility is available
for creating dynamic fracture with detonation waves. Blast wave measurement
capability is available for use with small charges.
- Transient jet initiation and DDT in hydrogen-air-steam mixtures
- Ignition energy measurements in aviation kerosene
- Inerting concentration measurements
- Flammability limits in multicomponent mixtures.
- Automated measurement of flame speeds by optical techniques.
- Modification of fuels by thermal and oxidative methods.
- A pulse detonation engine simulation facility.
Research studies in this laboratory have included:
Shock Tubes and Other Facilities
A number of other resources are available at GALCIT. These include a
general-purpose shock tube (150 mm diam), the T5 hypervelocity facility,
machine and electronic shops, photographic darkrooms and
other technical support such as the GC-MS available through the EAC.
A set of modifications to the T5 facility have been developed to enable
launching projectiles into combustible gas mixtures. This facility has been
used to study the initiation and stabilization of detonation waves on
- Effect of DDT on measured impulse for pulse detonation engines.
- Effect of obstacle type and spacing on DDT.
- Effect of area changes on pulse detonation engine impulse
- Effect of initiator size and type on pulse detonation engine impulse.
- Dynamic fracture of tubes by detonations
- Production of shock waves by rich fireballs
The 150-mm (6-in) shock tube has been used to study a number of issues in
recent years, including:
- Interaction of shock waves with liquid layers
- The production of high-velocity water
jets through shock loading.
- Ignition of combustion by shock-heated air jets
- The excitation of flexural waves by shocks inside thin-walled tubes.
- Fracture of plates by shock loading
- Initiation of detonation by annular gas jets and imploding shock waves
- Initiation of detonation by shock focusing