System and method for three dimensional particle imaging velocimetry and particle tracking velocimetry

1. A particle velocimetry system, comprising:

an input for receiving imaging data from a plurality of two-dimensional image sensors adapted for generating two-dimensional flow images of a three-dimensional particle laden fluid flow;

a memory storing a particle velocimetry algorithm for tracking the movement of particles in the particle laden fluid flow based on the flow images received from the plurality of image sensors; and

a processor programmed to execute the particle velocimetry algorithm to track the movement of particles in the particle laden fluid flow based on the flow images received from the image sensors, by:

executing a particle reconstruction routine to determine three-dimensional positions of particles in the particle laden fluid flow from the flow images received from the image sensors;

generating a three-dimensional particle distribution from the three-dimensional position data determined by the particle reconstruction routine; and

executing a recursive loop for iteratively executing the particle reconstruction routine and the generation of three-dimensional particle distributions, with the recursive iteration of the particle reconstruction routine being executed with the use of particle property data obtained from the prior executed iteration of the particle reconstruction routine and/or the generation of three-dimensional particle distributions.

2. The particle velocimetry system according to claim 1 , wherein the processor is programmed to execute the particle reconstruction routine by:

performing particle identification to identify two-dimensional particle images in the flow images received from the plurality of image sensors, and to determine two-dimensional positions of the identified particle images;

performing particle matching to match a plurality of particle images identified in a plurality of corresponding flow images on the basis that the matched particle images are determined to correspond to a common particle in the particle laden fluid flow; and

performing particle triangulation to determine three-dimensional positions of particles in the particle laden fluid flow based on the two-dimensional positions of matched particle images.

3. The particle velocimetry system according to claim 2 , wherein the processor is programmed, when performing particle identification, to:

identify target regions in the flow images that are determined to contain a particle image based on a first intensity value of pixels in the flow images;

identify in the target regions local peaks that are determined to represent a particle based on a second intensity value of pixels in the flow images;

define support sets of surrounding pixels around the identified local peaks based on commonalities in intensity values in pixels around the local peaks;

add, in each support set, an expected particle image based on bounds of the respective support set and location of the local peak in the respective support set; and

initialize each expected particle image to assign expected particle properties thereto based on properties of pixels at the respective local peak and support set.

4. The particle velocimetry system according to claim 3 , wherein the processor is programmed, when matching particle images, to associate the expected particle properties of a given particle image with each other particle image that the given particle image is matched with.

5. The particle velocimetry system according to claim 4 , wherein the processor is programmed, when executing a recursive loop, to:

extrapolate a two-dimensional particle trajectory based on a series of associated particle images at successive points in time to identify a two-dimensional particle position of an expected particle image a yet other point in time; and

associate expected particle properties of a particle image at a given point in time in the two-dimensional trajectory with pixels at the two-dimensional particle position identified by extrapolation of the two-dimensional particle trajectory.

6. The particle velocimetry system according to claim 5 , wherein the processor is programmed, when performing a recursive iteration of identifying local peaks, to identify a local peak at a pixel based on expected particle properties from a prior iteration of particle reconstruction that have been associated with that pixel based on the extrapolation of the two-dimensional particle trajectory.

7. The particle velocimetry system according to claim 5 , wherein the processor is programmed, when performing a recursive iteration of fitting expected particle images, to add a second expected particle image in a support set having another particle image therein based on expected particle properties from a prior iteration of particle reconstruction that have been associated with pixels in the support region based on the extrapolation of the two-dimensional particle trajectory.

8. The particle velocimetry system according to claim 5 , wherein the processor is programmed, when performing a recursive iteration of fitting expected particle images, to initialize an expected particle image to assign expected particle properties thereto based on properties of pixels at the respective local peak and support set, wherein the properties of pixels at the respective local peak and support set are inclusive of expected particle properties from a prior iteration of particle reconstruction that have been associated with those pixels based on the extrapolation of the two-dimensional particle trajectory.

9. The particle velocimetry system according to claim 5 , wherein the expected particle properties comprise at least one of: particle location, particle size, particle shape, and particle intensity.

10. The particle velocimetry system according to claim 3 , wherein the processor is programmed, when triangulating particle images, to associate the expected particle properties of matched particle images with a three-dimensional particle location triangulated from the matched particle images.

11. The particle velocimetry system according to claim 10 , wherein the processor is programmed, when executing a recursive loop, to:

project a previously triangulated three-dimensional particle position to identify a two-dimensional particle position of an expected particle image; and

associate expected particle properties of the three-dimensional particle position with pixels at the two-dimensional particle position identified by projection of the three-dimensional particle position.

12. The particle velocimetry system according to claim 11 , where

the processor is programmed, when performing a recursive iteration of identifying local peaks, to identify a local peak at a pixel based on expected particle properties from a prior iteration of particle reconstruction that have been associated with that pixel based on the projection of the three-dimensional particle position.

13. The particle velocimetry system according to claim 11 , wherein the processor is programmed, when performing a recursive iteration of fitting expected particle images, to add a second expected particle image in a support set having another particle image therein based on expected particle properties from a prior iteration of particle reconstruction that have been associated with pixels in the support region based on the projection of the three-dimensional particle position.

14. The particle velocimetry system according to claim 11 , wherein the processor is programmed, when performing a recursive iteration of fitting expected particle images, to initialize an expected particle image to assign expected particle properties thereto based on properties of pixels at the respective local peak and support set, wherein the properties of pixels at the respective local peak and support set are inclusive of expected particle properties from a prior iteration of particle reconstruction that have been associated with those pixels based on the projection of the three-dimensional particle position.

15. The particle velocimetry system according to claim 11 , wherein the expected particle properties comprise at least one of: particle location, particle size, particle shape, and particle intensity.

16. The particle velocimetry system according to claim 3 , wherein the expected particle properties comprise at least one of: particle location, particle size, particle shape, and particle intensity.

17. The particle velocimetry system according to claim 1 , wherein the processor is programmed to implement the particle velocimetry algorithm to execute an initial iteration of the particle reconstruction routine and generation of a three-dimensional particle distribution, and at least one recursive iteration of the particle reconstruction routine and generation of a three-dimensional particle distribution.

18. The particle velocimetry system according to claim 17 , wherein the processor is programmed to implement the particle velocimetry algorithm to execute recursive iterations of the particle reconstruction routine and generation of a three-dimensional particle distribution for a predetermined number of iterations.

19. The particle velocimetry system according to claim 18 , wherein the processor is programmed to implement the particle velocimetry algorithm to execute recursive iterations of the particle reconstruction routine and generation of a three-dimensional particle distribution until a threshold variation in positional data of the three-dimensional particle distribution is reached.

20. The particle velocimetry system according to claim 1 , wherein the property data comprises particle location, particle size, particle shape, and particle intensity.