Planar laser-induced fluorescence (PLIF) is an optical diagnostic technique widely used for flow visualization and quantitative measurements. PLIF has been shown to be used for velocity, concentration, temperature and pressure measurements. In PLIF, the flow is illuminated by a laser light sheet whose wavelength is tuned to excite a particular transition. A fraction of the ground state molecules of the flow absorbs the incident light and is excited to a higher electronic energy state. The excited species will after some time, usually in the order of few nanoseconds to microseconds, de-excite and emit light at a wavelength larger than the excitation wavelength. This light, fluorescence is captured on a digital camera.
A typical PLIF setup consists of
1. a source of light
laser: adjustble wavelength 190nm~350nm pulsed laser
2.lenses to form a sheet
3.fluorescent medium,
4. collection optics
UV-Vis optics
Wavelength select filter
5. detector
Intensified ccd camera.
6. calibration burner system
The light from the laser (usually a beam) is passed through a set of lenses and/or mirrors to form a sheet, which is then used to illuminate the medium. This medium is either made up of fluorescent material or can be seeded with a fluorescent substance. The signal is usually captured by a CCD or CMOS camera and can be related to the various properties of the medium..
1.Combustion
Experiments involving re-ignition at high altitude with laser and plasma igniters can provide significant insight into the immensely complex flows prevailing in these combustors. Typical types of species investigated within plasmas and in particular in combustion studies include OH, CH, NO, NH, CN, CO, and O2 radicals as well as excitations within atomic and ionic species.
2. Two Phase Flow