CN113218513B - Cooling device for infrared temperature measurement glass for high-temperature experiment - Google Patents

Abstract

The invention relates to a cooling device for infrared temperature measurement glass for high-temperature experiments, belonging to the field of gas turbines. There is an L-shaped cold air groove 1 in the downstream direction; during the high temperature infrared experiment, the introduced L-shaped cold air groove provides cooling air flow, and a thin film of air is formed on the surface of the infrared glass to isolate the high temperature mainstream. The narrow and long cold air outlet structure enables the cooling air to cover the entire surface of the infrared glass evenly. The chamfered structure downstream of the cold air improves the adherence of the downstream cold air. The cooling channel structure ensures that the infrared glass works within the normal temperature range, and will not interfere with the temperature field and the near-wall flow field of the temperature measurement target, so that the infrared glass can be used for high-temperature experiments at higher temperatures and keep the experimental data. accuracy.

Description

A cooling device for infrared temperature measuring glass used in high temperature experiments

technical field

The invention belongs to the field of gas turbines, in particular to a cooling device for infrared temperature measuring glass used in high temperature experiments.

Background technique

As the main device for energy conversion and utilization, gas turbines are widely used in the fields of power generation, aviation, chemical industry and mechanical power. With the sharp increase of energy demand and the increasingly prominent environmental problems, the power and thermal efficiency of gas turbines have been continuously improved, which put forward stricter requirements for the design of gas turbines. In order to cope with the increasing demand for energy and the environmental pollution caused by energy utilization. The combustion chamber is one of the most important heat-bearing components of a gas turbine. Under the action of high-temperature gas, its internal high-temperature structure needs to bear a huge thermal load (convection and radiation), thermal shock (changes in working conditions, etc.), etc. Continuously increasing the inlet gas temperature in the development and design of gas turbines can significantly improve the thermal efficiency of gas turbines, and at the same time improve the design of the combustion chamber to make the gas temperature distribution even and reduce the gas temperature in the combustion center area. The improved design significantly increases the gas temperature near the wall of the combustor flame tube, and the heat load of the combustor flame tube increases significantly under the action of high-temperature airflow, which seriously affects its service life and poses a threat to the operation safety of the entire gas turbine . In order to make the high temperature components work properly, a variety of cooling methods are required in the design of the gas turbine, and the experimental evaluation of various cooling methods is very important for the design of the gas turbine.

In heat transfer cooling experiments, thermal imaging cameras are widely used to measure the temperature distribution of the entire surface to obtain comprehensive cooling efficiency. With the expansion of infrared applications and the development of detector technology, the temperature measurement function of uncooled infrared cameras has been further improved. Infrared thermal imaging camera provides a new idea for the research of temperature field measurement technology in complex environment. In heat transfer cooling experiments related to gas turbines, thermal imaging cameras are often used to obtain temperature field information of an object in a closed channel. In this case, the thermal imaging camera needs to be used with infrared glass that can transmit certain radiation wavelengths. In the past, infrared thermal imaging cameras were generally used for medium and low temperature conditions (less than 350°C). With the continuous improvement of experimental methods, in order to get closer to the high temperature and high pressure environment in the real gas turbine flame tube in the experiment, to obtain more accurate flame The temperature field and flow field distribution inside the cylinder, and the experimental temperature has been continuously increased in recent years. In a high-temperature environment, the temperature of the infrared glass in direct contact with the high-temperature fluid rises rapidly, which will cause the glass to pyrolyze or block the transmission of infrared radiation, resulting in the failure of the infrared camera to capture the temperature field of the observed object normally.

Therefore, the development of a channel structure for infrared glass cooling in high-temperature infrared experiments has very important engineering application value for ensuring the safe and effective conduct of high-temperature heat transfer cooling experiments using infrared thermal imaging cameras.

In the existing infrared temperature measurement experiments inside the channel, the use of infrared glass is limited to medium and low temperature experiments within 350 °C. This is because commonly used infrared glasses such as ZnS will oxidatively decompose above a certain temperature. Infrared glass that can withstand high temperatures, such as sapphire, will absorb a large amount of infrared radiation at high temperatures and its own radiation is very strong, resulting in the inability of infrared cameras to obtain accurate temperature images. As the operating temperature of gas turbines continues to increase, the existing low-temperature experiments can no longer meet the development needs.

SUMMARY OF THE INVENTION

Technical problem to be solved:

In the existing technology, in the infrared heat transfer cooling experiment at a temperature above 350°C, the infrared glass cannot work normally, resulting in large deviations in temperature measurement or failure to measure the temperature. The device, through the internal cooling design of the channel, ensures that the infrared glass remains within its normal operating temperature range to ensure the accuracy of the temperature field captured by the infrared thermal imager, and at the same time ensures that the high-temperature infrared heat transfer cooling experiment can be carried out safely and effectively.

The technical scheme of the present invention is: a kind of cooling device that is used for the infrared temperature measurement glass of high temperature experiment, comprises experiment channel, infrared glass 2, observation window 3, has observation window 3 on the top wall of described experiment channel, and observes An infrared glass 2 is installed on the upper edge of the window 3, through which the temperature measurement experiment is carried out on the temperature measurement target in the experimental channel; it is characterized in that: there is a L on the top wall of the experimental channel along the downstream direction of the main flow. L-shaped cold air tank 1, the experimental channel is the mainstream channel 5; the L-shaped cold air tank 1 is opened upstream of the observation window 3, its inlet is located on the outer wall of the top wall of the experimental channel 5, and its outlet is located on the side wall of the observation window 3 , and located below the infrared glass; along the mainstream direction, the cross section of the L-shaped cold air tank 1 perpendicular to the top wall is L-shaped; the cooling gas enters the main channel through the L-shaped cold air tank 1, and covers the surface of the infrared glass to cool it;

The outlet width x of the L-shaped cold air groove 1 is equal to the width of the observation window 3, the outlet groove height h is 1/2 of the thickness of the top wall of the main channel 5, and the distance between the upper edge of the outlet and the infrared glass 2 is 1/2h; L-shaped The length of the cold air groove 1 along the main flow direction is 20h;

The temperature measurement target 4 is facing the observation window 3, and the distance s from the observation window 3 satisfies the following formula:

s≥H+2h=32h

Among them, H is the height of the mainstream channel.

A further technical solution of the present invention is: the edge of the observation window downstream of the cooling gas fed into the L-shaped cold air groove 1 is set as a chamfered structure 6 to ensure good adhesion of the cold air to the wall.

A further technical solution of the present invention is: the vertical distance from the lower edge of the outlet of the L-shaped cold air tank 1 to the temperature measurement target is not less than 30.5h, which can ensure that the cooling gas introduced from the L-shaped cold air tank 1 will not affect the temperature measurement target. Temperature Field.

beneficial effect

The beneficial effects of the present invention are:

(1) The mainstream passage among the present invention utilizes the stepped structure produced after the infrared glass is fixed, and an L-shaped cold air groove is designed in the upstream direction of the wall surface of the experimental passage below the infrared glass, and the cold air is blown into the mainstream passage through the groove and covered on the surface of the infrared glass. After the cold air is exported, it maintains the same flow direction as the main flow, which reduces its mixing with the main flow and reduces the influence on the temperature of the main flow. The inlet of the L-shaped cold air slot is located downstream of the main inlet and upstream of the infrared glass, which avoids the impact of the introduced cold air on the main inlet and does not require other structural designs, saving materials and costs.

(2) The outlet of the cold air tank is located in the middle of the wall thickness, and the size of the outlet of the cold air tank is adapted to the experimental channel and infrared glass. Among them, the outlet width x is equal to the width of the infrared observation window, the groove height h is 1/2 of the upper wall thickness of the main channel, and the upper edge of the cold air groove outlet is 1/2h away from the infrared glass to ensure that the inner surface of the infrared glass is isolated from the high-temperature air flow. The slot opened in the middle of the wall avoids damage to the fixed structure of the infrared glass, and the slot with the same width as the observation window makes the glass covered with cold air in the horizontal direction.

(3) The outlet of the cold air tank adopts a slit structure, that is, x>>h. The cold air with a small flow rate can obtain greater kinetic energy in this slit structure, so that the cold air can cover the entire surface of the infrared glass.

(4) The chamfered structure is designed downstream of the cold air outlet to ensure that the cold air has good adhesion to the wall. The cold air can effectively adhere to the infrared glass and the upper wall of the mainstream channel to prevent it from penetrating into the center of the mainstream and affecting the temperature and flow field of the mainstream.

(5) Control the distance between the temperature measurement target and the cold air tank, the cold air introduced will inevitably affect the mainstream; the present invention is calculated by commercial fluid mechanics calculation software, and the distance is controlled at s≥H+2h=32h, and the cold air flow is attached On the upper wall of the main flow channel, until it flows out of the main flow channel, the influence of the cold air on the main flow is limited near the upper wall of the main flow channel. At the same time, under the common working conditions of the current gas turbine, the flow field near the temperature measurement target will not affect the cold air upwards. If it cannot be set according to the range defined by the present invention, it will affect the mainstream gas or the temperature field of the temperature measurement target.

Therefore, the overall technical idea of the present invention is to design an infrared glass cooling device without affecting the flow field and temperature field near the temperature measurement target, so that the infrared glass can work normally within the temperature range, and at the same time ensure that the cooling device is simple and feasible.

To sum up, in the channel structure used for cooling infrared glass under high-temperature infrared experiments provided by the present invention, an L-shaped air-conditioning groove is set on the upper wall of the main flow channel to cool the infrared glass. Under the condition that the density product ratio is 3, the maximum temperature of the inner surface of the infrared glass does not exceed 340K, which is lower than the high temperature working limit of 700K, which can ensure that the infrared glass can work in the normal temperature range, and can also minimize the impact of the cooling device on the mainstream and The influence of the temperature field and the flow field of the temperature measurement target. The infrared glass cooling channel structure of the present invention has universal applicability to relevant high-temperature infrared heat transfer cooling experiments.

Description of drawings

Fig. 1 is a schematic diagram of the channel structure for infrared glass cooling under high-temperature infrared experiments of the present invention;

Fig. 2 is a cross-sectional view with the experimental channel structure A of the present invention;

Fig. 3 is to have the experimental channel structure of the present invention isometric sectional view;

Explanation of reference signs: 1-L-shaped cold air tank, 2-infrared glass, 3-temperature measurement window, 4-temperature measurement target, 5-main channel, 6-chamfer structure.

Detailed ways

The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Orientation indicated by rear, left, right, vertical, horizontal, top, bottom, inside, outside, clockwise, counterclockwise, etc. The positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as limiting the invention.

Referring to FIG. 1 , in the infrared glass cooling channel structure of the present invention, there is an L-shaped cold air groove 1 inside the top wall of the main channel 5 downstream of the main entrance and upstream of the infrared glass 2 . Utilizing the step structure produced after the infrared glass is fixed, there is an L-shaped cold air groove structure on the upper wall of the mainstream experimental channel. The inlet of the cold air groove is located downstream of the main flow inlet, which will not interfere with the high temperature main flow inlet. The cold air is blown in from the direction perpendicular to the main flow, and after entering the main channel, it covers the surface of the infrared glass 2 and moves downstream. The cold air adheres well to the upper wall of the main channel during the whole process from entering the main channel to leaving the main channel. A chamfer structure is provided at the downstream position of the cold air outlet to ensure good adhesion of the cold air to the wall.

Referring to Fig. 2, the width x of the outlet of the L-shaped cold air groove of the present invention is as long as the observation window, and the height h is 1/2 of the thickness of the upper wall of the main channel and is located in the middle of the wall, that is, 0.5h away from the upper and lower end surfaces. The distance between the cold air tank and the temperature measurement object, that is, the height H of the main channel and the thickness of the upper wall are determined according to the experimental conditions.

Referring to FIG. 3 , the cold air in the present invention enters the main channel in the same direction as the main flow after passing through the L-shaped cold air groove. Most of the cold air flowing along the mainstream is confined to the upper wall area near the observation window, which does not affect the temperature and flow field of the mainstream near the lower wall, nor does it affect the temperature field and flow field of the temperature measurement target surface.

The temperature measurement target 4 is facing the observation window 3, and the distance s from the observation window 3 satisfies the following formula:

s≥H+2h=32h.

In the implementation of the present invention, firstly, through CFD simulation, the height H of the main channel, the height h of the outlet of the cold air groove and the flow rate of the cold air are determined, so that the cold air can evenly cover the entire surface of the infrared glass and have good adhesion to the wall. That is, by adopting the infrared glass cooling channel structure of the present invention, while the infrared glass is fully cooled, the introduced cold air will not affect the original temperature field of the temperature measurement target.

Technical principle of the present invention is as follows:

Referring to Figure 3, using the principle of slot cooling, a cold air slot is introduced, so that the surface of the infrared glass that is in direct contact with the high-temperature mainstream is covered with a cooling air film. In addition, the use of the outlet slit structure and the downstream chamfer structure ensures full coverage of the cold air and good adhesion to the wall. Therefore, adopting the infrared glass cooling channel structure of the present invention can effectively reduce the temperature of the infrared glass without affecting the temperature field and flow field of the temperature measurement target, ensuring that the high temperature experiment is carried out smoothly and the error of the obtained experimental results is smaller.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limitations to the present invention. Variations, modifications, substitutions, and modifications to the above-described embodiments are possible within the scope of the present invention.

Claims (2)

1. A cooling device for high-temperature experiment infrared temperature-measuring glass, comprising an experimental channel, infrared glass (2), observation window (3), the top wall of the experimental channel has an observation window (3), and An infrared glass (2) is installed on the upper edge of the observation window (3), through which the temperature measurement target (4) in the experimental channel is subjected to a temperature measurement experiment; it is characterized in that: at the top of the experimental channel There is an L-shaped cold air groove (1) on the wall along the downstream direction of the main flow, and the experimental channel is the main flow channel (5); the L-shaped cold air groove (1) is opened upstream of the observation window (3), and its entrance is located in the experimental On the outer wall of the top wall of the channel (5), the outlet is located on the side wall of the observation window (3) and below the infrared glass (2); along the main flow direction, the L-shaped cold air groove (1) is perpendicular to the section of the top wall It is L-shaped; the cooling gas enters the main channel through the L-shaped cold air groove (1), and covers the surface of the infrared glass to cool it; The outlet width x of the L-shaped cold air groove (1) is equal to the width of the observation window (3), the height h of the outlet groove is 1/2 of the thickness of the top wall of the main channel (5), and the upper edge of the outlet is connected to the infrared glass (2). The distance is 1/2h; the length of the L-shaped cold air groove (1) along the main flow direction is 20h; The temperature measurement target (4) is facing the observation window (3), and the distance s from the observation window (3) satisfies the following formula: s≥H+2h=32h Among them, H is the height of the mainstream channel; The edge of the observation window downstream of the cooling gas introduced into the L-shaped cold air groove (1) is set as a chamfered structure (6), which is used to ensure good adhesion of the cold air; the L-shaped experimental channel is formed in the experimental channel to ensure The tightness of the channel and the fixing requirements of the infrared glass are met. 2. The cooling device for infrared temperature measuring glass in high temperature experiments according to claim 1, characterized in that: the vertical distance from the lower edge of the outlet of the L-shaped cold air tank (1) to the temperature measurement target is not less than 30.5h, which can ensure The cooling gas introduced from the L-shaped cold air groove (1) will not affect the temperature field of the temperature measurement target.

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