A fast response fluid temperature sensor based on fiber optic sensing

Abstract

This invention provides a fast-response fluid temperature sensor based on fiber optic sensing. The structure comprises three parts: a variable-diameter tube, a column, and a fiber optic temperature sensor. As the fluid enters the variable-diameter tube and transitions from a wider to a narrower section, Bernoulli's principle causes the pressure to decrease and the flow velocity to increase as the tube diameter narrows. This results in faster heat exchange at the fiber optic temperature sensor, thus accelerating the temperature response. In the fiber optic temperature sensor, a through-hole with wider ends and a narrower center is designed in the middle of the fiber. The fiber core is placed next to the through-hole, increasing the heat exchange area of ​​the sensor. Furthermore, Bernoulli's principle increases the fluid velocity at the narrower center, further accelerating heat exchange between the fiber optic temperature-sensitive element and the surrounding fluid, thus further speeding up the temperature response.

Description

Technical Field

[0001] This invention relates to the field of temperature sensor technology, and in particular to a fast-response temperature sensing method utilizing Bernoulli's principle. Background Technology

[0002] Temperature sensors are instruments used to measure temperature and sense temperature changes, converting them into output signals. They are widely used in machinery manufacturing, aerospace, petrochemical, and metallurgical industries. The response speed of a temperature sensor determines whether it can accurately and promptly measure changes in external temperature. The main factors affecting temperature response time include sensor size, heat exchange surface area and shape, and material thermal conductivity. Patent CN204043813U utilizes a suspended micro / nano-scale thin-film resistor as the temperature sensing element. This design results in a small size, light weight, low heat capacity, and extremely small time constant, enabling rapid temperature measurement. Patent CN103033281B mounts the temperature sensing element in the bottom diameter section of a trapezoidal temperature-sensing sleeve, providing a smaller heat exchange surface area while maintaining a fast temperature response speed through protective encapsulation of the sensing element with an external sleeve.

[0003] In fluid environments, fluid velocity also affects heat transfer between the environment and the sensor. The faster the ambient flow, the faster the heat exchange between the fluid and the sensor, and the faster the temperature sensor's temperature response. Based on this, this invention utilizes Bernoulli's principle to accelerate the fluid flow near the sensor and the fiber optic grating through structural design, thereby accelerating heat exchange and increasing the sensor's temperature response speed. This method can also be used for the external encapsulation of other temperature sensor structures, further enhancing the temperature sensor's temperature response performance by adjusting the form of external fluid flow, providing a new approach to accelerating sensor temperature response speed. Summary of the Invention

[0004] The purpose of this invention is to provide a fast-response temperature sensing method, which accelerates the temperature response speed of the fiber optic temperature sensor by increasing the flow rate of the fluid around the fiber core.

[0005] The objective of this invention is achieved as follows: it comprises three parts: a variable diameter tube 1, a column 2, and an optical fiber temperature sensor 3. The variable diameter tube is a tubular structure that is thicker at both ends and thinner in the middle; there are two columns, with their bottom ends fixed to the two sides of the tube wall and their top ends located at the center height of the variable diameter tube; the optical fiber temperature sensor 3 is a microstructured optical fiber with an internal through-hole structure, where the through-hole 5 is thicker at both ends and thinner in the middle, with the fiber core close to the through-hole. A temperature-sensitive unit is located in the fiber core at the position corresponding to the thinner diameter through-hole. The two ends of the optical fiber temperature sensor are fixed to the top of the column, so that the optical fiber temperature sensor is suspended on the thinner diameter axis of the variable diameter tube.

[0006] Preferably, the transition section from the thicker pipe to the thinner pipe at the front of the reducer should gradually become thinner, and the transition section from the thinner pipe to the thicker pipe at the rear should gradually become thicker.

[0007] Preferably, the fixed column has a streamlined cross-sectional structure and a small windward surface area.

[0008] Preferably, within a suitable size range, the ratio of the cross-sectional area of ​​the thicker tube to the thinner tube in the reducing pipe should be as large as possible.

[0009] The working principle of this invention is as follows: the through-hole design increases the heat exchange area between the optical fiber and its surrounding environment, while reducing the distance to the external heat source, thereby accelerating the temperature response speed. Under flow conditions, when fluid enters the through-hole in the optical fiber temperature sensor section, due to Bernoulli's principle, the flow velocity increases as it moves from the thicker section to the thinner section, thus accelerating heat exchange between the optical fiber sensing element and its surrounding environment, improving the temperature response speed. For the external encapsulation structure, when fluid enters the variable-diameter tube, the flow velocity also increases as it moves from the thicker section to the thinner section, again due to Bernoulli's principle, further accelerating heat exchange between the optical fiber temperature sensor and its surrounding environment, further improving the temperature response speed.

[0010] The beneficial effects of the present invention are as follows: Compared with the prior art, the beneficial effects of the present invention are: (1) By using an external encapsulation design, the temperature response speed of the fiber optic temperature sensor is improved by accelerating the flow rate of the surrounding fluid. (2) The heat exchange area between the fiber optic temperature sensor with a through-hole structure and the surrounding environment is increased, and the distance from the external heat source is reduced, thereby accelerating the temperature response speed. (3) The fiber optic temperature sensor with a variable diameter through-hole structure can increase the flow rate of the surrounding fluid of the fiber optic sensing element, thereby accelerating the temperature response speed. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a fast-response fluid temperature sensor based on fiber optic sensing.

[0012] Figure 1 In the diagram: 1 is a reducing pipe, 2 is a column, and 3 is a fiber optic temperature sensor. Fluid flows in from the left side of the reducing pipe and out from the right side.

[0013] Figure 2 This is a schematic diagram of the fiber optic temperature sensor structure.

[0014] Figure 2 In the diagram: 4 is the fiber cladding, 5 is the central through-hole, 6 is the fiber core, and 7 is the fiber grating. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0016] This invention discloses a fast-response temperature sensing method, comprising three main parts: a variable-diameter tube 1, columns 2, and an optical fiber temperature sensor 3. The optical fiber temperature sensor 3 is implemented by tapering a microstructured optical fiber with a through-hole structure and a fiber core 6 located at the edge of the through-hole, and then writing a fiber Bragg grating at the narrower diameter position as the sensing element. The bottom ends of the two columns are fixed to the two side walls of the variable-diameter tube, and the top ends are located at the center height of the variable-diameter tube; the optical fiber temperature sensor is fixed through the top ends of the two columns.

[0017] The reducing tube is a tubular structure that is thicker at both ends and thinner in the middle; there are two columns, the bottom of which are fixed to the two sides of the reducing tube wall, and the top of which is located at the center height of the reducing tube; the fiber temperature sensor 3 is a microstructured fiber with a through hole structure inside, the through hole 5 is thicker at both ends and thinner in the middle, the fiber core 6 is close to the through hole, and there is a temperature sensitive unit at the fiber core at the position corresponding to the thin diameter through hole. The two ends of the fiber temperature sensor are fixed to the top of the column, so that the fiber temperature sensor is suspended on the thin diameter axis of the reducing tube.

[0018] By placing this structure in a fluid environment, the through-hole design in the fiber optic temperature sensor increases the heat exchange area between the fiber and its surroundings, while reducing the distance to the external heat source, thus accelerating the temperature response. When fluid enters the through-hole of the fiber optic temperature sensor, the flow velocity increases as it transitions from a thicker to a thinner section due to Bernoulli's principle, resulting in faster heat exchange between the fiber grating 7 and its surroundings, further accelerating the temperature response. Similarly, when fluid enters a reducing pipe, the pressure decreases and the flow velocity increases as the pipe diameter narrows, again due to Bernoulli's principle, leading to faster heat exchange between the fiber optic temperature sensor and its surroundings, thus accelerating the temperature response.

[0019] In summary, this invention designs a fast-response fluid temperature sensor based on fiber optic sensing, comprising three parts: a variable-diameter pipe, a column, and a fiber optic temperature sensor. As the fluid enters the variable-diameter pipe and transitions from a wider to a narrower section, Bernoulli's principle causes the pipe diameter to decrease, resulting in lower pressure and higher flow velocity. This leads to faster heat exchange at the fiber optic temperature sensor, thereby accelerating the temperature response. In the fiber optic temperature sensor, a through-hole with wider ends and a narrower center is designed in the middle of the fiber. The fiber core is placed next to the through-hole, increasing the heat exchange area of ​​the sensor. Furthermore, Bernoulli's principle increases the fluid velocity at the narrower center, further accelerating heat exchange between the fiber optic temperature-sensitive element and the surrounding fluid, thus further speeding up the temperature response.

Claims

1. A fast-response fluid temperature sensor based on fiber optic sensing, characterized in that: The system includes a variable diameter tube, columns, and a fiber optic temperature sensor. The variable diameter tube is a tubular structure that is thicker at both ends and thinner in the middle. There are two columns, with the bottom ends fixed to the two sides of the tube wall and the top ends located at the center height of the tube. The fiber optic temperature sensor is a microstructured optical fiber with a through-hole structure inside. The through-hole is thicker at both ends and thinner in the middle, and the fiber core is close to the through-hole. There is a temperature-sensitive unit in the fiber core at the position corresponding to the thinner through-hole. The two ends of the fiber optic temperature sensor are fixed to the top of the column, so that the fiber optic temperature sensor is suspended on the thinner diameter axis of the variable diameter tube.

2. The fast-response fluid temperature sensor based on fiber optic sensing according to claim 1, characterized in that: The transition section from the thicker to the thinner tube at the front of the reducer should gradually become thinner, while the transition section from the thinner to the thicker tube at the rear should gradually become thicker.

3. A fast-response fluid temperature sensor based on fiber optic sensing according to claim 1 or 2, characterized in that: The column has a streamlined cross-sectional structure.

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