Fiber optical fabry-perot flow test device and test method with local bending diversion structure

Patent metadata

Field	Value
Publication number	US-10508938-B2
Application number	US-201615559429-A
Country	US
Kind code	B2
Filing date	Oct 27, 2016
Priority date	Jun 20, 2016
Publication date	Dec 17, 2019
Grant date	Dec 17, 2019

Abstract

Fiber optical Fabry-Perot flow test device with local bending diversion structure, having an inlet flange, a test tube and an outlet flange, with both a fiber optical Fabry-Perot pressure sensor at high-pressure-side and a fiber optical Fabry-Perot pressure sensor at low-pressure-side, which are fixedly connected to the test tube through an auxiliary connecting device.

First claim

What is claimed is:

1. A fiber optical Fabry-Perot flow test device with local bending diversion structure, consisting of a main body, wherein the main body comprises an inlet flange, a test tube and an outlet flange which are successively connected from left to right, the test tube having linear ends and an arc-shaped middle portion, a fiber optical Fabry-Perot pressure sensor with a diaphragm provided at high-pressure-side and a fiber optical Fabry-Perot pressure sensor with a diaphragm provided at low-pressure-side, which are respectively arranged with an optical transmission fiber internally and are communicated with the test tube, being provided on upper and lower sides of an arc-shaped wall in the middle portion of the test tube along the symmetric axis thereof; and the fiber optical Fabry-Perot pressure sensor at high-pressure-side is connected to a first circulator which is connected to a first light source and a first optical signal demodulation system, and the first optical signal demodulation system is connected to a first linear array CCD camera, and the fiber optical Fabry-Perot pressure sensor at low-pressure-side is connected to a second circulator which is connected to a second light source and a second optical signal demodulation system, the second optical signal demodulation system is connected to a second linear array CCD camera, both an output terminal of the first linear array CCD camera and an output terminal of the second linear array CCD camera are connected to an input terminal of a signal conditioning and acquisition circuit, and an output terminal of the signal conditioning and acquisition circuit is connected to a data processing unit, wherein both the fiber optical Fabry-Perot pressure sensor at high-pressure-side and the fiber optical Fabry-Perot pressure sensor at low-pressure-side are fixedly connected to the test tube through an auxiliary connecting device which is designed as a hollow cylinder, and the auxiliary connecting device comprises a fixed connection structure, a sealing structure and a gland packing layer, which are successively arranged from outside to inside.

2. The fiber optical Fabry-Perot flow test device with local bending diversion structure according to claim 1 , wherein both the fiber optical Fabry-Perot pressure sensor at high-pressure-side and the fiber optical Fabry-Perot pressure sensor at low-pressure-side are packaged by laser welding, and for those sensors, a Fabry-Perot cavity is formed from monocrystalline silicon wafers and glass sheets having etched pits thereon.

3. A test method performed by using the fiber optical Fabry-Perot flow test device with local bending diversion structure according to claim 2 , comprising the following steps of:
(1) connecting the fiber optical Fabry-Perot flow test device with local bending diversion structure to a pipe to be tested, turning on the first light source and the second light source, and allowing a fluid to form a high pressure concentrated area and a low pressure concentrated area on an outer side and an inner side of the arc-shaped section when flowing through the arc-shaped section in the middle portion of the test tube;
(2) sensing a high pressure signal and a low pressure signal in the arc-shaped section in the middle portion of the test tube by the fiber optical Fabry-Perot pressure sensor at high-pressure-side and the fiber optical Fabry-Perot pressure sensor at low-pressure-side, respectively, the high pressure signal and the low pressure signal directly acting on the diaphragms of the fiber optical Fabry-Perot pressure sensor at high-pressure-side and the fiber optical Fabry-Perot pressure sensor at low-pressure-side, respectively, so that a length of each Fabry-Perot cavity changes, both high pressure information and low pressure information being implied in an optical path difference in the respective reflected light signal variations;
(3) transmitting a reflected light signal at high pressure side into the first optical signal demodulation system through the first circulator, transmitting a reflected light signal at low pressure side into the second optical signal demodulation system through the second circulator, and demodulating the reflected light signals containing different optical path difference information into spatial low-coherence interference patterns by the first optical signal demodulation system and the second optical signal demodulation system, respectively;
(4) receiving the spatial low-coherence interference pattern from the first optical signal demodulation system by the first linear array CCD camera, and converting the pattern into a high-pressure-side electrical signal, and receiving the spatial low-coherence interference pattern from the second optical signal demodulation system by the second linear array CCD camera, and converting the pattern into a low-pressure-side electrical signal; and
(5) transmitting the high-pressure-side electrical signal and the low-pressure-side electrical signal to the data processing unit through the signal conditioning and acquisition circuit; calculating an absolute phase difference Δ α s between the high pressure side and the low pressure side, and then calculating an absolute pressure difference ΔP between the high pressure side and the low pressure side according to the formula

Δ
⁢
P

=

Δα
s

⁢

16
⁢

El
3

3
⁢

(

D
2

)

4

⁢

(

1
-

v
2

)

⁢

(

1

-
2

⁢

k
s

)

;

wherein, E is an elastic modulus of the diaphragm material, D is the diameter of the diaphragm, l is the thickness of the diaphragm, v is a Poisson's ratio and k s is the wave number at a point s; and finally, calculating a fluid flow Q in the pipe to be tested according to a forced vortex theory

Q
=

8
·

βπ
⁢
A

Assignees

• Univ Tianjin

Inventors

• Liu Tiegen
• Jiang Junfeng
• Yang Huijia
• Liu Kun
• Wang Shuang
• Zhang Weihang

Classifications

• G01F1/38

  the pressure or differential pressure being measured by means of a movable element, e.g. diaphragm, piston, Bourdon tube or flexible capsule · CPC title

• G01F1/383 Primary

  with electrical or electro-mechanical indication · CPC title

• G01F1/661 Primary

  using light · CPC title

• G01F1/34

  by measuring pressure or differential pressure · CPC title