Digital Particle Tracking Velocimetry (DPTV)

 

Digital Particle Tracking Velocimetry (DPTV), in contrast, is the low particle concentration mode of DPIV. Since, the required seeding density is lower in comparison with DPIV, tracking the movement of the individual particles (~5 - 50 microns (in air)) within the area of interest yields better results than the conventional statistical analysis methods (auto-correlation / cross-correlation) due to a higher detection rate which can be achieved within the measurement window. The DPTV technique could have an imaging window larger than DPIV because of the sparsely seeded flow. DPTV could arguably yield better positional accuracy than DPIV because it allows one to one tracking of the same particle (centriod) between the two image frames.  Particle Tracking Velocimetry can be extended to measure the out-of-plane and in-plane velocity components by using stereo imaging technique.

 

DPTV experimental set up for the in-cylinder flow in an i.c.engine.

 

A typical DPTV in-cylinder velocity vector field 

(velocity vectors distribute unevenly))



Typical DPTV Equipments: DPTV Equipments:


Laser system (CW or double-pulsed with good laser beam quality), laser sheet generation optics (high energy mirrors, lenses, posts and mounts), seeding particles generator (solid or liquid vapour), high quality CCD camera, pulse generator for equipment synchronisation (optional), high performance computer (large memory and high capacity hard disk), CD burner for data storage (optional), D/A & A/D converter board, frame grabber card and image processing software.

General Reference:

Grant, I., 1997. Particle image velocimetry: a review, Proc. Instn. Mech. Engrs. Vol 211, Part C, pp.55-76.

Verdict and Comment:

A highly versatile but underrated planar (near instantaneous) flow measurement technique. Main interests in the technique are from a few universities and engine manufacturers.