Method and device for analyzing flows

• US 6,642,999 B2
• Filed: 04/18/2002
• Issued: 11/04/2003
• Est. Priority Date: 04/13/2000
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Reymann, Klaus, Arndt, Stefan, Heinen, Christian
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US10/018,196
• Publication Number:
  US 20020135750A1
• Time in Patent Office: 565 Days
• Field of Search: 738/61, 356/28
• US Class Current: 356/28
• CPC Class Codes: G01P 5/001 Full-field flow measurement, e.g. determining flow velocity and direction in a whole region at the same time, flow visualisation
• CPC Class Codes: G01P 5/20 using particles entrained by a fluid stream G01P5/22 takes precedence

Abstract

A method and device for analyzing and quantifying flows for the three-dimensional determination of flow velocity components or the visualization of flows in fluids or gases. An illuminating device generates electromagnetic radiation of a predefined color to scan a detection space in the form of light planes arranged spatially one behind the other that are at least roughly parallel, and that are generated temporally one after the other. As a result, electromagnetic waves are generated in the detection space by particles characterizing the flow, and are detected using at least one image detector which records two-dimensional color images. The frequency, frequency spectrum, and/or intensity detected by at the least one of the image detectors is changed by an as a function of time.

Claims

1. A method for analyzing a flow in at least one of a fluid and a gas for providing at least one of a three-dimensional determination of velocity components of the flow and a three-dimensional visualization of the flow, the method comprising:

arranging spatially one after another in a detection space at least two roughly parallel light planes, and generating temporally the at least two roughly parallel light planes one after another using electromagnetic radiation of a predefined color; and

scanning the detection space using the at least two roughly parallel light planes, and detecting electromagnetic waves that are at least one of partially emitted and scattered by particles that are contained in the detection space and that characterize the flow using at least one image detector,

wherein in the step of scanning, changing as a function of time at least one of a frequency, a frequency spectrum and an intensity detected by at least one of the at least one image detector of the electromagnetic waves that are at least one of partially emitted and scattered by the particles.

2. The method of claim 1, wherein in the step of scanning, at least one of (i) a spectral composition in images of at least one area of the detection space recorded one after another by at least one of the at least one image detector, and (ii) a spectral composition within one image of at least one area of the detection space recorded by at least one of the at least one image detector is changed as a function of time.

3. The method of claim 2, wherein in the step of scanning, at least one of (i) a spectral sensitivity of at least one of the at least one image detector, (ii) an intensity impinging on at least one of the at least one image detector, and (iii) a duration of the electromagnetic waves impinging on at least one of the at least one image detector is changed as a function of time at least one of within one recorded image and between recorded images.

4. The method of claim 1, wherein at least one image detector includes at least one CCD camera.

5. The method of claim 1, wherein the electromagnetic radiation of a predetermined color includes at least one of a color laser beam and a monochromatic laser beam.

6. The method of claim 1, wherein the electromagnetic radiation of a predetermined color is generated in one of a pulse-wave mode and a continuous wave mode.

7. The method of claim 1, wherein the at least two roughly parallel light planes, which are generated temporally one after another and arranged spatially one after another, scan the detection space such that the at least one image detector detects an illumination of the detection space that is at least roughly continuous temporally.

8. The method of claim 1, wherein a depth of focus of at least one of the at least one image detector, during the scanning of the detection space, is adjusted one of continuously and step-by-step, so that the at least two roughly parallel light planes, which are arranged spatially one after another and generated temporally one after another, are imaged at least fairly sharply at a location of the at least one image detector.

9. The method of claim 1, wherein:

at least two scannings of the detection space immediately follow one another and take place in a short time interval so as to provide a multiplicity of periodic scannings;

a two-dimensional image of the detection space is recorded using the at least one image detector; and

at least one of emitted light and scattered light from the particles is measured in the at least two scannings of the detection space.

10. The method of claim 1, wherein two-dimensional images of the detection space are recorded using the at least one image detector, and measuring at least one of emitted light and scattered from the particles in at least two images recorded shortly after one another.

11. The method of claim 1, the step of scanning includes evaluating at least one two-dimensional recorded image of the detection space using at least one of a particle tracking algorithm and a correlation method based on a spectral composition of the recorded images, and determining at least one of a location of the particles in a scanned area of a three-dimensional detection space and a spatial shift of the particles as a function of time from the at least one two-dimensional recorded image.

12. The method of claim 10, wherein local flow velocities of individual particles are determined based on a time duration between scannings.

13. The method of claim 1, wherein a temporal change of at least one of a detected frequency, a detected frequency spectrum and a detected intensity occurs periodically.

14. The method of claim 1, wherein a temporal change of at least one of a detected frequency, a detected frequency spectrum and a detected intensity is one of correlated and synchronized with a periodic scanning of the detection space in at least one of images recorded one after another by at least one of the at least one image detector and within one image recorded by at least one of the at least one image detector, and a scanning period is one of equal to and a whole number multiple of a period of the temporal change of the at least one of the detected frequency, the detected frequency spectrum and the detected intensity.

15. A device for analyzing a flow in at least one of a fluid and a gas for providing at least one of a three-dimensional determination of velocity components of the flow and a three-dimensional visualization of the flow, the device comprising:

a first arrangement to arrange spatially one after another in a detection space at least two roughly parallel light planes, and to generate temporally the at least two roughly parallel light planes one after another using electromagnetic radiation having at least one of a predefined frequency, a predefined frequency spectrum and a predefined color, the first arrangement including an illuminating device;

a second arrangement to scan at least regions of the detection space using the at least two roughly parallel light planes, and to detect electromagnetic waves that are at least one of partially emitted and scattered by particles that are contained in the detection space and that characterize the flow, the second arrangement including at least one image detector; and

a third arrangement to change as a function of time at least one of a frequency, a frequency spectrum and an intensity detected by at least one of the at least one image detector of the electromagnetic waves that are at least one of partially emitted and scattered by the particles.

16. The device of claim 15, wherein the illuminating device includes at least one of a light source, a laser, a collimator, a polygon scanner, and a galvanometer scanner.

17. The device of claim 15, wherein the at least one image detector is arranged on at least one end face of the detection space, the at least one end face being parallel to the at least two roughly parallel light planes.

18. The device of claim 15, wherein the at least one image detector includes at least one of a black/white camera, a color camera, a CCD camera and a 3-chip camera to at least one of record and depict in false colors two-dimensional images of at least one area of the detection space.

19. The device of claim 15 wherein the at least one image detector includes a device for adjusting a focus depth.

20. The device of claim 15, wherein the device includes at least one of an evaluation unit and a computer to at least one of evaluate and store recorded two-dimensional images.

21. The device of claim 15, wherein the device includes a correlation unit to at least one of correlate and synchronize a temporal change of at least one of a detected frequency, a detected frequency spectrum and a detected intensity based on a scanning of the detection space by the illuminating device.

22. The device of claim 15, wherein:

the at least one image detector includes a CCD camera having three sensor chips to detect at least one of three different colors and three different frequency ranges; and

the third arrangement includes an electronic control unit integrated in the CCD camera, the electronic control unit being operable to selectively change as a function of time at least one of a spectral sensitivity of at least one of the three sensor chips, an integral sensitivity of at least one of the three sensor chips and an intensity impinging on at least one of the three sensor chips.

23. The device of claim 15, wherein:

the at least one image detector includes at least three CCD cameras to detect an identical area of the detection space; and

the third arrangement includes an electronic control unit to change as a function of time at least one of a detected frequency, a detected frequency spectrum and a detected intensity.

24. The device of claim 15, wherein the third arrangement includes a filter installed in front of at least one of the at least one image detector, the at least one image detector including at least one of a sensor chip, a CCD camera, in particular, and the filter includes includes one of a rotating gray filter, a rotating color filter, and a rotating polarization filter having an upstream polarizer.