Fluid Measuring System and Long Focal Point Optical System

• US 20070268602A1
• Filed: 03/31/2005
• Published: 11/22/2007
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Tokyo Electric Power Company Holdings, Incorporated (Nuclear Damage Compensation Decommissioning Facilitation Corp.)
• Original Assignee: Korea Electric Power Corporation (Government of South Korea)
• Inventors: Tezuka, Hideaki, Mori, Michitsugu
• Granted Patent: US 7,826,653 B2
• Time in Patent Office: Days
• US Class Current: 359/871
• 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
• CPC Class Codes: G06T 7/20 Analysis of motion motion estimation for coding, decoding, compressing or decompressing digital video signals H04N19/43, H04N19/51

Abstract

To enable detection of flow of a distant fluid to be measured to provide a new application of a PIV system at a practical level.

A fluid measurement system of the present invention includes a long focus optical system 3 at a CCD camera 2, and an image processing means 43 for comparing particle images taken at two time points for analysis. The long focus optical system 3 is provided with a shield 32 which shields a part including a central portion of a main mirror 31 at an arbitrary shield rate. As a result, the particle image of a tracer is enlarged with its contour kept clear, that is, in focus, and therefore, the image having a luminance which allows analysis by the PIV method can be taken in spite of use of the long focus optical system.

Claims

1. A fluid measurement system comprising an imaging means for taking images of particles contained in a fluid to be measured at small time intervals, a control means for controlling said imaging means, and an image processing means for comparing luminance pattern distributions at a plurality of consecutive time points obtained by said imaging means to measure a moving direction and a moving amount of a particle group, and analyzing a flow field of the fluid to be measured,

said imaging means comprising a long focus optical system being of a long distance type capable of imaging a fluid to be measured a long distance away, and

said long focus optical system being provided with a shield which shields a part including a central portion of a main mirror at an arbitrary shield rate.

2. The fluid measurement system according to claim 1, wherein

the shield rate found by a ratio of a diameter of said shield to an aperture of said long focus optical system is provided to be arbitrarily adjustable.

3. The fluid measurement system according to claim 1 or 2, wherein

said shield rate is set in a range of 20% to 60% when one particle image obtained by the imaging means across two pixels or more, and is set in a range of 0% to 40% when a plurality of particle images are contained in one pixel.

4. The fluid measurement system according to any one of claims 1 to 3, wherein

a secondary mirror included in said long focus optical system is supported by parallel plate glasses whose surfaces are disposed to be oriented in a direction perpendicular to an optical axis of a main mirror in the lens barrel.

5. The fluid measurement system according to any one of claims 1 to 4, wherein

said imaging means is of a long distance type capable of imaging a luminance pattern distribution by natural light reflection in the fluid to be measured a long distance away.

6. The fluid measurement system according to any one of claim 1 to claim 4, further comprising:

a laser light input means for inputting a laser light in a sheet form into the fluid to be measured,

wherein said imaging means is of a long distance type capable of imaging a luminance pattern distribution by the laser light reflection in the fluid to be measured a long distance away.

7. The fluid measurement system according to any one of claim 1 to claim 6, wherein

said imaging means is of a long distance type capable of imaging the fluid to be measured 10 m or greater and 20 km or less away from the set position of said imaging means.

8. A long focus optical system constructed by supporting a main mirror and a secondary mirror in a mirror barrel, comprising

a shield which shields a part including a central portion of the main mirror at a predetermined shield rate.

9. The long focus optical system according to claim 8, wherein

the shield rate found by a diameter of said shield with respect to an aperture is settable in a range from 20% to 60% when one particle image obtained by an imaging means is across two pixels or more, and is settable in a range from 0% to 40% when a plurality of particle images are contained in one pixel.

10. The long focus optical system according to claim 8 or claim 9, wherein

said secondary mirror is supported by parallel plate glasses whose surfaces are disposed to be oriented in a direction perpendicular to the optical axis of a main mirror in the lens barrel.

11. The long focus optical system according to any one of claim 7 to claim 10, said long focus optical system being used in an imaging means in a fluid measurement system comprising an imaging means for taking images of particles contained in a fluid to be measured a long distance away at small time intervals, a control means for controlling said imaging means, and an image processing means for comparing luminance pattern distributions at a plurality of consecutive time points obtained by said imaging means to measure a moving direction and a moving amount of a particle group, and analyzing a flow field of the fluid to be measured.