Combustion Chamber



Drop Tower



Measurement Capsule



Use of Drag Shield

• For micro gravity experiment, the measurement time (1 s approx.) is enough to study the burning history of small diameter droplets. Hence, the corresponding height of the tower was fixed at 6.5 m giving allowance for the foundation and damping system to arrest the fall of the combustion chamber. The drop height was 5 m.


• The purpose of the drag shield is to reduce the air resistance acting on the combustion chamber and aids in achieving microgravity condition.


• The capsule comprised of:
  • The combustion chamber
  • The light source (A 15 W compact fluorescent lamp)
  • CCD video camera
  • 12 V D.C source
  • 220 V AC supply switch board
  • Ignition apparatus

• In order to capture the droplet combustion process, backlighting was used. Luminous photography was used to study flame structure of the droplet during the entire burning process.


• A 15 W CFL bulb was placed right behind the droplet in the optical axis of the video camera to backlit the image.


• The video camera (30 fps) used is a Sony HD CCD camera with an optical magnification of 10x in order to achieve further magnification without compromising the clarity of the acquired images.

For micro gravity experiments:


1. Install the instruments and test chamber. Install the camera and illumination bulb.


2. Lift the capsule to the required height on the drop tower (~7 m) and transfer the load onto the release mechanism. Maintain center of gravity of the load properly.


3. Form the droplet on the bead of glass filament using the injector.


4. Activate the imaging system and perform optical alignment.


5. Heat the ignition coil for one or two seconds and then trigger the circuit using the circuit control panel.


6. Activate the release mechanism as soon as the drop starts burning. Initial combustion occurs under normal gravity and subsequently under micro gravity.


7. Perform image analysis to obtain droplet diameters at different time instants.

For normal gravity experiments:

Above procedure is followed except steps 2 and 6.