CN205748774U - High-temperature resistant optical fiber grating pressure sensor - Google Patents

Abstract

A kind of high-temperature resistant optical fiber grating pressure sensor; including fiber grating, thin cylinder, protection sleeve, connecting sleeve and oil-feed dop; thin cylinder is positioned at protection sleeve; fiber grating is pasted onto thin cylinder outer surface; oil-feed dop is connected with protection sleeve seal, states oil-feed dop and is connected with thin cylinder, and thin cylinder left end portion is designed as hollow-core construction; thin cylinder right end portion is designed as solid construction, connecting sleeve is connected with protection sleeve right-hand member.The utility model has the advantages that, temperature and pressure two parameter measurement can be carried out under high temperature, high pressure adverse circumstances, realize temperature and pressure real time on-line monitoring purpose under heavy crude heat extraction application circumstances, meet high accuracy, high sensitivity and the requirement on a large scale measured simultaneously.

Description

High-temperature resistant optical fiber grating pressure sensor

Technical field:

This utility model belongs to Fiber Grating Sensors Technology field, is especially a kind of high-temperature resistant optical fiber grating pressure and passes Sensor.

Background technology:

Fiber grating is a kind of optic fibre passive device that development in recent years is extremely rapid.Along with fiber grating manufactures skill Art the most perfect, application achievements growing, fiber grating has become the fiber optic passive device of the most most development prospect One of.Fiber grating is the heliosensitivity utilizing fiber optic materials, makes inside of optical fibre generation the most permanent periodically or non-periodically Variations in refractive index and make.Owing to fiber grating is formed at inside of optical fibre, have that all-fiber, insertion loss are low, become This low advantage, and by the design of optical grating construction being met the various spectral characteristics of specific needs, thus The fields such as civil buildings, bridge dam and Aero-Space suffer from wide application prospect.

The application of fiber grating facilitates the all-fiber of optical fiber sensing system, miniaturization, integrated and networking, because of This grating sensing technique, once proposition, is the most quickly favored, and emerges rapidly as an emerging technology, becomes current light One of fastest-rising field in fine sensing.But, up to the present, the domestic research to fiber-optic grating sensor falls relatively After, research contents also has focused largely on temperature and strain sensing aspect.Comparatively speaking, to fiber bragg grating pressure sensor, Radix Triplostegiae Grandiflorae The research of quantity sensor still belongs to the exploratory stage, is badly in need of studying high-temperature resistant optical fiber grating pressure sensor, thick to meet The demand of the monitoring in real time of the temperature and pressure of oil thermal recovery application circumstances.

In view of the traditional measurement method major part of high-temperature resistant optical fiber grating pressure sensor is single just for temperature, pressure etc. Parameter measures, to temperature, Research on measuring technique relatively fewer of pressure Radix Triplostegiae Grandiflorae amount, therefore, the scope of sensor measurement, Precision and sensitivity can not meet the measurement environmental requirement of reality simultaneously, and the error existed is bigger.

It addition, traditional processing technology thereof of high-temperature resistant optical fiber grating pressure sensor is complex, and the knot of sensor The design of structure, outward appearance, processing technique etc. is required for further optimizing；Meanwhile, sensor packaging technology design aspect there is also Unreasonable part, cause precision, the sensitivity decrease measured.

Utility model content:

The technical problems to be solved in the utility model is to provide one can carry out temperature under high temperature, high pressure adverse circumstances Degree and pressure two parameter measurement, it is achieved temperature and pressure real time on-line monitoring purpose under heavy crude heat extraction application circumstances, simultaneously Meet the high accuracy of measurement, high sensitivity and the high-temperature resistant optical fiber grating pressure sensor required on a large scale.

Technical solution of the present utility model is to provide a kind of high-temperature resistant optical fiber grating pressure with following structure and passes Sensor, it includes fiber grating, and wherein, pressure transducer also includes thin cylinder, protection sleeve and oil-feed dop, thin cylinder Being positioned at protection sleeve, fiber grating is pasted onto thin cylinder outer surface, and oil-feed dop is connected with protection sleeve seal, oil-feed card Head is connected with thin cylinder, and thin cylinder left end portion is designed as hollow-core construction, and thin cylinder right end portion is designed as solid knot Structure.

After using above structure, compared with prior art, this utility model has the advantage that

1, this utility model high-temperature resistant optical fiber grating pressure sensor is based on distributed optical fiber temperature measurement technology and fiber grating Sensing technology, by being pasted onto on the axial direction of thin cylinder by fiber grating, thus realizes heavy crude heat extraction special applications ring Temperature and the purpose of pressure real time on-line monitoring under border.

2, in terms of sensor probe technique for temperature compensation, this utility model high-temperature resistant optical fiber grating pressure sensor is by optical fiber Grating is pasted onto thin cylinder outer surface, and thin cylinder left end portion is designed as hollow-core construction to measure pressure, right part Set up separately and be calculated as solid construction to measure temperature, owing to fiber grating material is consistent, consistent to the responsiveness of temperature, therefore same In environment, fiber bragg grating pressure sensor is the same with fiber-optical grating temperature sensor to the response of temperature, is not stressed Fiber-optical grating temperature sensor provides temperature-compensating to the fiber bragg grating pressure sensor of pressure-sensitive, can eliminate temperature and pass pressure The impact of sensor, so that this utility model can carry out temperature and pressure two parameter measurement under high temperature, high pressure adverse circumstances.

3, the thin-wall tubular structure of design in this utility model high-temperature resistant optical fiber grating pressure sensor is the fullest The feasibility that foot is measured, also meets the high accuracy of measurement and large-scale requirement simultaneously；On the other hand protection set in structure Cylinder serves protective effect to fiber grating, it is to avoid the destruction that it is produced by external environment condition.

4, this utility model high-temperature resistant optical fiber grating pressure sensor is at key position, and i.e. oil-feed dop is with protection sleeve even Meet place, use the design of enclosed package, pressure limit that fiber bragg grating pressure sensor measure and measurement are greatly improved Precision, has important practical value and economic worth.

Preferably, high-temperature resistant optical fiber grating pressure sensor described in the utility model, wherein, thin cylinder left end is hollow The axial length of part can be equal with the axial length of thin cylinder right-hand member solid section.The benefit that axial length is equal is to ensure that The strain of hollow parts reaches bigger deflection, thus realizes the pressure measurement range of viscous crude environment.

Preferably, high-temperature resistant optical fiber grating pressure sensor described in the utility model, wherein, thin cylinder right-hand member is solid The afterbody of part can be designed with round boss, round boss can be provided with at least one logical with what protection sleeve barrel chamber communicated Hole.The effect of design round boss is to prevent viscous crude from producing hoop vibration after entering thin cylinder, and the benefit arranging through hole is Facilitate penetrating of optical fiber.

Preferably, high-temperature resistant optical fiber grating pressure sensor described in the utility model, wherein, the material that thin cylinder is selected Material can be LY16 duralumin, hard alumin ium alloy.LY duralumin, hard alumin ium alloy has stronger Corrosion Protection, and elastic modelling quantity meets viscous crude ambient pressure The needs measured.

Preferably, high-temperature resistant optical fiber grating pressure sensor described in the utility model, wherein, oil-feed dop and protection set Cylinder is tightly connected and can use structure in detail below: for threadeding between oil-feed dop with protection sleeve, and in threaded connection place Coating high-temp glue.This sealing structure can improve pressure limit and the precision of measurement that this utility model is measured further.

Preferably, high-temperature resistant optical fiber grating pressure sensor described in the utility model, wherein, protection sleeve and oil-feed card The material that head is selected can be all 304 rustless steels.

Preferably, high-temperature resistant optical fiber grating pressure sensor described in the utility model, wherein, pressure transducer also can wrap Including a connecting sleeve, connecting sleeve is connected with protection sleeve right-hand member.Connection Card shell type is in order to realize the distributed survey of multiple spot The design measured and carry out, such that it is able to realize the measurement of remote problem and pressure.

Preferably, high-temperature resistant optical fiber grating pressure sensor described in the utility model, wherein, the material that connecting sleeve is selected Material is 304 rustless steels.304 stainless have stronger tensile strength and yield strength, and Corrosion Protection is good.

Accompanying drawing illustrates:

Fig. 1 is the structural representation of this utility model high-temperature resistant optical fiber grating pressure sensor；

Fig. 2 is the structural representation of thin cylinder in this utility model high-temperature resistant optical fiber grating pressure sensor；

Fig. 3 is the structural representation protecting sleeve in this utility model high-temperature resistant optical fiber grating pressure sensor；

Fig. 4 is the structural representation of oil-feed dop in this utility model high-temperature resistant optical fiber grating pressure sensor；

Fig. 5 is the structural representation of connecting sleeve in this utility model high-temperature resistant optical fiber grating pressure sensor；

Fig. 6 is the structure for amplifying schematic diagram at " A " position in Fig. 2；

Fig. 7 is this utility model high-temperature resistant optical fiber grating pressure sensor design procedure schematic flow sheet；

Fig. 8 is theory of the fiber optical schematic diagram.

Detailed description of the invention:

With detailed description of the invention, this utility model high-temperature resistant optical fiber grating pressure sensor is made into one below in conjunction with the accompanying drawings Step describes in detail:

As shown in Figure 1, Figure 2, shown in Fig. 3, Fig. 4 and Fig. 5, this utility model high-temperature resistant optical fiber grating pressure sensor includes optical fiber Grating 7, thin cylinder 1, protection sleeve 2, oil-feed dop 3 and connecting sleeve 4.Thin cylinder 1 is to measure temperature and pressure Enhanced sensitivity element, this utility model uses high-temp glue to be fixed on fiber grating 7 encapsulation at thin cylinder 1 outer surface, was encapsulating Journey needs apply a certain amount of prestressing force to fiber grating, so that transducer range meets uses requirement.Outer surface is pasted The thin cylinder 1 having fiber grating 7 is positioned at protection sleeve 2.Thin cylinder 1 left end portion is designed as hollow-core construction to measure Pressure, thin cylinder 1 right end portion is designed as solid construction to measure temperature, and thin cylinder about 1 two ends separately design sky The effect of core structure and solid construction is the impact that can eliminate temperature to pressure transducer, reaches the purpose of temperature-compensating.Oil-feed For threadeding between dop 3 with protection sleeve 2, and coat high-temp glue, oil-feed dop 3 and thin cylinder 1 in threaded connection place Between be interference fit.The effect of oil-feed dop 3 is to ensure that viscous crude can stably enter in thin cylinder 1.Connecting sleeve 4 Threadeding with protection sleeve 2 right-hand member, protection sleeve 2, partly in order to thin cylinder 1 within Bao Hu, prevents external environment It being polluted and destroys, being on the other hand to protect the fiber grating 7 on thin cylinder 1 surface, in order to avoid being destroyed And there is the phenomenons such as fracture, the design that connecting sleeve 4 is able to realize multiple spot distributed measurement and carries out, final realization is remote The temperature of distance and the measurement of pressure.The material that in this utility model high-temperature resistant optical fiber grating pressure sensor, thin cylinder 1 is selected Material is LY16 duralumin, hard alumin ium alloy, and the material that protection sleeve 2, oil-feed dop 3 and connecting sleeve 4 are selected is 304 rustless steels.

As in figure 2 it is shown, the material that in this utility model high-temperature resistant optical fiber grating pressure sensor, thin cylinder 1 is selected is LY16 duralumin, hard alumin ium alloy, entire length is 120mm, and wherein the axial length of left end hollow parts is 60mm, right-hand member solid section Axial length is also 60mm.It addition, the afterbody of thin cylinder 1 right-hand member solid section is designed with round boss 6, on round boss 6 It is provided with three to be circumferentially distributed, and the through hole 5 communicated with protection sleeve 2 barrel chamber.

As shown in Figure 6, this utility model high-temperature resistant optical fiber grating pressure sensor in the design process, is first depending on viscous crude The actual demand of thermal recovery application circumstances, carries out the Preliminary design of sensor, secondly utilizes the structure that Preliminary design is good ANSYS simulation software carries out statics Analysis, the stress that goes out according to simulation analysis, strain, the then preliminary knot to sensor probe Structure carries out perfect, then sensor carries out pressure test, and is fed back to front end by the result tested, the most perfect sensing The overall structure of device.

Specific design step is as follows:

1, structure design

First it is that sensor is carried out preliminary structure design, primarily to temperature and pressure under exploitation high temperature and high pressure environment The Fibre Optical Sensor of power two parameter measurement, it is achieved temperature and pressure real time on-line monitoring under adverse circumstances.The technology of temperature section Performance indications: monitoring distance is 0～6000m, the temperature range of measurement is 0～350 DEG C, and the precision of measurement is ± 2 DEG C, positioning accurate Degree is 1.5m, and the measurement time is 30s；The technical performance index of pressure portion: the range of measurement is 0～250MPa, resolution For 1%FS, response time is 10s, and operating temperature is 0～250 DEG C.By These parameters requirement, the biography of this utility model design Sense probe is thin-wall tubular structure, and the material of selection is duralumin, hard alumin ium alloy, outside is protected it by protection sleeve, one end with enter Oil card head connects, and the other end is connected with connecting sleeve.

2, structure simulation analysis

Thin cylinder in this utility model carries out mechanical analysis mainly by ANSYS simulation software to it, the thinnest Wall cylinder operating temperature is 0～350 DEG C, and the pressure range that its inner surface bears is 0～25MPa, retrains thin cylinder Arranging with parameter, the temperature chosen is 350 DEG C, and pressure is 25MPa, obtains the strain deformation figure of thin cylinder.Emulated by ANSYS The result analyzed understands: the thin cylinder maximum microstrain reached under high temperature, high pressure is 709 μ ε, can be the pressure in later stage Power test provides reference frame.

3, pressure test

After the design of high-temperature resistant optical fiber grating pressure sensor structure and simulation analysis, at thin cylinder surface mount light Fine grating, the linearity of fiber grating to be ensured in taping process, and leave certain pretightning force；Oil-feed dop and protection set The position high-temp glue sealing that cylinder is threaded, then will carry out pressure test to it to it.During doing pressure test, Every the wavelength that 2MPa record fiber grating is corresponding, due to the limit value of experimental condition, pressure test is surveyed under normal temperature condition Measure, and the maximum pressure measured is 25MPa.

This utility model high-temperature resistant optical fiber grating pressure sensor principle is: when grating constant changes, grating Resonance wavelength will change.The external condition such as temperature, pressure change that act on fiber grating will cause screen periods With the change of refractive index, thus cause the change of optic fiber grating wavelength, by the change of detection fiber grating wavelength, temperature can be obtained The information such as degree, pressure.FBG wavelength is with the effective refractive index of fibre core and grating fringe cyclomorphosis, therefore, when ambient temperature occurs During change, the elasto-optical effect caused due to thermal expansion effects, thermo-optic effect and the fiber grating built-in thermal stress of fiber grating, The change of optic fiber grating wavelength will be caused；FBG wavelength depends on grating fringe cycle and the effective refractive index of reverse coupled mould.? Cause in the extraneous factor that FBG wave length shift detects, be the most directly stress, strain parameter.Grating is stretched or squeezes Pressure, all causes the change in grating fringe cycle, and the elasto-optical effect that grating itself is had makes effective refractive index also with the external world The change of stress state and change.

Specifically, according to the coupled mode theory of fiber grating, when a branch of broadband light incides in fiber grating, refraction The periodic structure of rate makes the narrow band light of certain specific wavelength be reflected, and the wavelength of reflection light meets Bragg and scatters condition.Optical fiber Grating is also called optical fiber Bragg raster, the central wavelength lambda of its reflection light_BEffective refractive index n with fiber grating_effWith grating week Phase Λ meets following relation:

λ_B=2n_effΛ (1)

From above formula, the centre wavelength of fiber grating reflection light depends primarily on grating period A and effective refractive index n_eff.When fiber grating experiences ambient temperature or pressure changes, cycle and the effective refractive index of grating can be caused Change, thus cause the skew of reflecting light length.Therefore, i.e. be would know that by the change of detection fiber optical grating reflection optical wavelength Ambient temperature or pressure information, the most as shown in Figure 7.Broadband spectral incident in fiber core reflects through fiber grating After, obtaining the reflectance spectrum of the narrow band light containing specific wavelength, the light of other wavelength all passes through fiber grating and defines transmission light Spectrum.When the parameter such as ambient temperature, pressure changes, and the drift of Bragg wavelength is represented by:

λ_B=2 Λ Δ n_eff+2n_effΔΛ (2)

Therefore, only when ambient temperature changes, thermal expansion effects the screen periods caused is changed to:

Δ Λ=α Λ Δ T (3)

In formula, α is the thermal coefficient of expansion of optical fiber.Thermo-optical coeffecient causes effective refractive index to be changed to:

Δn_e=ξ n_e·ΔT (4)

In formula, ξ is the thermo-optical coeffecient of optical fiber, represents refractive index variation with temperature rate.Therefore the temperature of optical fiber Bragg raster Degree sensitivity coefficient is:

$K_T=\frac{{\mathrm{\Δ\λ}}_B}{\mathrm{\Δ}T}/{\mathrm{\λ}}_B=\mathrm{\α}+\mathrm{\ξ}---\left(5\right)$

Pressure influence Bragg wavelength is also due to the contraction of screen periods and elasto-optical effect causes, it is assumed that temperature field and Transverse pressure keeps constant, and optical fiber is in a uniform pressure field P, owing to there is no shear stress, therefore the stress suffered by optical fiber State can indicate with a triaxiality vector:

$\mathrm{\δ}=\left[\begin{array}{c}{\mathrm{\δ}}_x\\ {\mathrm{\δ}}_y\\ {\mathrm{\δ}}_z\end{array}\right]=\left[\begin{array}{c}-P\\ -P\\ -P\end{array}\right]---\left(6\right)$

Corresponding strain regime can also indicate with a stress vector:

$\mathrm{\ϵ}=\left[\begin{array}{c}{\mathrm{\δ}}_x\\ {\mathrm{\δ}}_y\\ {\mathrm{\δ}}_z\end{array}\right]=\left[\begin{array}{c}-P(1-2v)/E\\ -P(1-2v)/E\\ -P(1-2v)/E\end{array}\right]---\left(7\right)$

In formula, v is the Poisson's ratio of fiber optic materials, and E is the Young's modulus of fiber optic materials.Meanwhile, axial strain can cause grating The change of pitch:

Δ Λ=Λ ε_z=-Λ P (1-2v)/E (8)

Being analyzed from above, fiber grating pair temperature and pressure is the most sensitive, when measuring the most a certain parameter, and can not Avoid to be affected by another parameter so that measurement error even causes fiber-optic grating sensor to apply very greatly.Cause This, must take measures to distinguish these parameters when measuring in actual applications.

Owing to measured object ambient temperature is typically the accurate survey of change, fiber grating pair to be realized strain or stress Amount then needs measurement result is carried out temperature-compensating.This key technology uses reference optical fiber grating temperature compensation method, is answering Becoming measurement fiber grating and be placed around a fiber grating freely, it is not affected by stress, only senses the change of temperature.With The temperature variation that reference optical fiber grating records is to revise the temperature wavelength change impact on measuring strain fiber grating, thus reaches Effect to temperature-compensating, it is achieved accurately measure.

Embodiments described above is only to be described preferred implementation of the present utility model, not to this reality It is defined by novel scope, on the premise of without departing from this utility model design spirit, those of ordinary skill in the art couple Various deformation that the technical solution of the utility model is made and improvement, all should fall into the guarantor that this utility model claims determine In the range of protecting.

Claims (8)

1. a high-temperature resistant optical fiber grating pressure sensor, including fiber grating (7), it is characterised in that: pressure transducer also wraps Including thin cylinder (1), protection sleeve (2) and oil-feed dop (3), described thin cylinder (1) is positioned at protection sleeve (2), described Fiber grating (7) is pasted onto thin cylinder (1) outer surface, and described oil-feed dop (3) is tightly connected with protection sleeve (2), described Oil-feed dop (3) is connected with thin cylinder (1), and described thin cylinder (1) left end portion is designed as hollow-core construction, described thin-wall circular Cylinder (1) right end portion is designed as solid construction.

High-temperature resistant optical fiber grating pressure sensor the most according to claim 1, it is characterised in that: described thin cylinder (1) The axial length of left end hollow parts is equal with the axial length of thin cylinder (1) right-hand member solid section.

High-temperature resistant optical fiber grating pressure sensor the most according to claim 1, it is characterised in that: described thin cylinder (1) The afterbody of right-hand member solid section is designed with round boss (6), and described round boss (6) is provided with at least one and protection sleeve (2) through hole (5) that barrel chamber communicates.

High-temperature resistant optical fiber grating pressure sensor the most according to claim 1, it is characterised in that: described thin cylinder (1) The material selected is LY16 duralumin, hard alumin ium alloy.

High-temperature resistant optical fiber grating pressure sensor the most according to claim 1, it is characterised in that: described oil-feed dop (3) It is tightly connected with protection sleeve (2) and refers to, for threadeding between described oil-feed dop (3) with protection sleeve (2), and at screw thread Junction coating high-temp glue.

High-temperature resistant optical fiber grating pressure sensor the most according to claim 1, it is characterised in that: described protection sleeve (2) The material selected with oil-feed dop (3) is 304 rustless steels.

High-temperature resistant optical fiber grating pressure sensor the most according to claim 1, it is characterised in that: pressure transducer also includes One connecting sleeve (4), described connecting sleeve (4) is connected with protection sleeve (2) right-hand member.

High-temperature resistant optical fiber grating pressure sensor the most according to claim 7, it is characterised in that: described connecting sleeve (4) The material selected is 304 rustless steels.