Experimental device and method for researching flow heat exchange characteristics of high-temperature gas dense triangular rod bundle channel

Abstract

The invention discloses an experimental device and method for researching the flow heat exchange characteristic of a high-temperature gas dense triangular rod bundle channel. The experimental device comprises an inlet pipeline, an inlet cavity, a heating cavity, a bent heating rod, a positioning grid, a flow equalizing pore plate and an outlet pipeline, three bent heating rods which are densely and triangularly arranged are arranged in the heating chamber to form a dense triangular rod bundle channel; the bent heating rod expands the outlet distance at the non-heating section through the bending design, and is matched with the trapezoidal conical section of the outlet cavity to realize sealing; a flow equalizing pore plate is arranged in the inlet cavity, a built-in thermocouple is arranged on the inner wall face of the heating rod, and positioning grillwork is arranged in front of and behind the heating section. The device is suitable for a dense triangular rod bundle channel experiment of a high-temperature and high-pressure gas working medium, the problems of outlet sealing and wall surface temperature measurement of a dense rod bundle channel are effectively solved, high-temperature deformation of the heating rod is prevented, and accurate flow heat exchange characteristic data can be obtained.

Description

Technical Field

[0001] This invention relates to the field of heat transfer characteristics research on dense gas rod bundle channels at high temperatures, and specifically to an experimental apparatus and method for studying the heat transfer characteristics of dense gas triangular rod bundle channels at high temperatures. Background Technology

[0002] As a key development direction for advanced nuclear energy systems, gas-cooled fast reactors typically employ a dense grid structure composed of fuel rods in their cores. In the field of nuclear reactors, a rod bundle arrangement with a grid diameter ratio (P / D, i.e., the ratio of the center distance to the outer diameter of the fuel rods) of less than or equal to 1.3 is called a dense grid. Within the dense grid rod bundle channels, the flow and heat transfer behavior of the high-temperature gas coolant is extremely complex, exhibiting characteristics significantly different from those in conventional pipes. Therefore, precise flow and heat transfer data must be obtained through specialized experimental studies to guide core design and safety analysis. However, existing technologies have significant shortcomings in experimental studies targeting high-temperature gas dense rod bundle channels. On the one hand, most experimental studies on rod bundle channels use water or liquid metal as the working fluid, while research on high-temperature gas working fluids is very limited, failing to accurately simulate the actual operating conditions of gas-cooled fast reactors. On the other hand, existing high-temperature gas experimental devices are mainly limited to geometrically simple channels or non-dense rod bundle channels, lacking designs for dense rod bundle channels. The spacing between rods in dense rod bundle channels is on the order of millimeters. This extremely small spacing presents a series of technical challenges for the placement of temperature sensors, the sealing design under high temperature and high pressure conditions, and the control of high-temperature bending deformation of the rod bundle channels. Therefore, for experiments on the heat transfer characteristics of high-temperature gas flow in dense triangular rod bundle channels, an experimental device design that can solve the above-mentioned problems is needed. Summary of the Invention

[0003] To overcome the problems existing in the prior art, the present invention aims to provide an experimental apparatus and method for studying the flow heat transfer characteristics of high-temperature gas in dense triangular rod bundle channels. This invention solves technical problems such as the difficulty in arranging sensors in dense rod bundle channels, the difficulty in sealing under high temperature and high pressure, the easy bending and deformation of heating rods, and the non-uniform inlet flow field. It provides a test section design that can meet the requirements of airtightness, uniform heat flow conditions, and thermal parameter measurement for studying the flow heat transfer characteristics of high-temperature gas in dense triangular rod bundle channels.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: An experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow includes an inlet pipe 1, an inlet chamber 2, an inlet temperature measuring conduit 3, an inlet temperature measuring thermocouple 4, an inlet flange 1, an inlet flange 2, an inlet pressure tapping pipe 7, a heating chamber 8, an outlet pressure tapping pipe 9, an outlet flange 1, an outlet flange 10, an outlet flange 2, a straight pipe section of the outlet chamber 12, a trapezoidal conical section of the outlet chamber 13, an outlet pipe 14, an outlet temperature measuring conduit 15, and an outlet temperature measuring thermocouple 16. 17. Outlet temperature measuring conduit 2; 18. Outlet temperature measuring thermocouple 2; 19. Bending heating rod outlet connector 1; 20. Bending heating rod outlet connector 2; 21. Bending heating rod outlet connector 3; 22. Bending heating rod 1; 23. Bending heating rod 2; 24. Inlet positioning grid; 25. Outlet positioning grid; 26. Bending heating rod 1 wall surface temperature measuring thermocouple; 30. Bending heating rod 2 wall surface temperature measuring thermocouple; 31. Bending heating rod 3 wall surface temperature measuring thermocouple; 32. Inlet flow equalization orifice plate; 33. The inlet pipe 1 is connected to the front end of the inlet chamber 2. The inlet chamber 2 is provided with an inlet flow equalization plate 33 to ensure that the gas flow field distribution in the rod bundle channel area is uniform. The inlet temperature measuring conduit 3 is arranged between the inlet flow equalization plate 33 and the inlet flange 5. The inlet temperature measuring thermocouple 4 is installed through the inlet temperature measuring conduit 3, and its measuring end is located at the central axis of the inlet chamber 2. The inlet end of the heating chamber 8 is connected to the inlet chamber 2 via inlet flange 5 and inlet flange 6, and the outlet end is connected to the straight pipe section 12 of the outlet chamber via outlet flange 10 and outlet flange 11. The heating chamber 8 is equipped with a dense triangular rod bundle consisting of bent heating rod 22, bent heating rod 23 and bent heating rod 24. The arrangement of the dense triangular rod bundle satisfies the condition that the ratio of the center distance of the heating rod to the outer diameter of the heating rod is less than or equal to 1.3, so as to simulate a compact grid structure. The inlet pressure tapping pipe 7 and the outlet pressure tapping pipe 9 are located at the beginning and end positions of the heating area, respectively. The inlet positioning grid 25 is arranged between the inlet pressure tapping pipe 7 and the inlet flange 5, and the outlet positioning grid 26 is arranged between the outlet pressure tapping pipe 9 and the outlet flange 10; the inlet positioning grid 25 and the outlet positioning grid 26 are used to support and fix the tightly arranged rod bundle to prevent the heating rod from bending and deforming. The rear end of the straight pipe section 12 of the oral cavity is connected to the trapezoidal conical section 13 of the oral cavity, and the outlet pipe 14 is connected to the upper end of the trapezoidal conical section 13 of the oral cavity; the curved heating rod 1 22, the curved heating rod 23 and the curved heating rod 3 24 pass through the trapezoidal conical section 13 of the oral cavity and are led out through the curved heating rod outlet connector 19, the curved heating rod outlet connector 20 and the curved heating rod outlet connector 3 21 respectively.

[0005] Preferably, the first bending heating rod 22, the second bending heating rod 23, and the third bending heating rod 24 are heated only in designated areas, with the remaining areas being non-heated sections. Specifically, the first bending heating rod 22 is provided with a first bending heating area 27, the second bending heating rod 23 is provided with a second bending heating area 28, and the third bending heating rod 24 is provided with a third bending heating area 29. The first bending heating rod 22, the second bending heating rod 23, and the third bending heating rod 24 are bent in two sections in the middle of the non-heated section near the outlet, so that the distance between the bending heating rods when they pass through the trapezoidal conical section 13 of the oral cavity is greater than the distance between them in the heating area, thereby providing space for the arrangement and sealing of the first bending heating rod outlet connector 19, the second bending heating rod outlet connector 20, and the third bending heating rod outlet connector 21.

[0006] Preferably, the inlet heads of the first bent heating rod 22, the second bent heating rod 23, and the third bent heating rod 24 are designed with a conical structure to reduce flow field disturbance when high-temperature gas enters the rod bundle channel.

[0007] Preferably, the experimental apparatus adopts a built-in temperature measurement scheme. The thermocouple 30 for measuring the temperature of the first wall surface of the bent heating rod is built into the inner wall surface of the first bent heating rod 22, the thermocouple 31 for measuring the temperature of the second wall surface of the bent heating rod is built into the inner wall surface of the second bent heating rod 23, and the thermocouple 32 for measuring the temperature of the third wall surface of the bent heating rod is built into the inner wall surface of the third bent heating rod 24. The thermocouples 30, 31, and 32 for measuring the temperature of the first, second, and third wall surfaces of the bent heating rod are all arranged on the side opposite to the bending direction of the corresponding bent heating rod, and are arranged and led out close to the inner wall surface.

[0008] Preferably, the trapezoidal conical section 13 of the oral cavity is welded to the straight pipe section 12 of the oral cavity. The trapezoidal conical section 13 of the oral cavity is used to accommodate the increased spacing of the bent heating rods at the bend. The bent heating rods 1-22, 23-23, and 3-24 are led out from the outlet side of the trapezoidal conical section 13 of the oral cavity and are sealed and fastened by the ferrules at the outlet connectors 1-19, 20, and 31.

[0009] Preferably, the outlet temperature measuring conduit 15 is arranged on the lower side of the trapezoidal conical section 13 of the outlet chamber, perpendicular to the central axis of the cavity. The outlet temperature measuring thermocouple 16 is arranged through the outlet temperature measuring conduit 15 and is used to measure the outlet temperature of the bent heating rod bundle. The outlet pipe 14 is arranged on the upper side of the trapezoidal conical section 13 of the outlet chamber. The outlet temperature measuring conduit 17 is arranged perpendicular to the outlet pipe 14. The outlet temperature measuring thermocouple 18 is arranged through the outlet temperature measuring conduit 17 and is used to measure the outlet temperature of the outlet pipe 14.

[0010] Preferably, the inlet flange 5 and the inlet flange 6, and the outlet flange 10 and the outlet flange 11 are all fastened together by bolts and nuts, and a sealing gasket is provided at the connection end face to ensure the airtightness of the chamber connection.

[0011] Preferably, the inlet pipe 1, the inlet oral cavity 2, the heating chamber 8, the straight pipe section 12 of the outlet oral cavity, the trapezoidal conical section 13 of the outlet oral cavity, the outlet pipe 14, the bent heating rod 1 22, the bent heating rod 23 and the bent heating rod 3 24 are made of high-temperature resistant stainless steel.

[0012] Preferably, the inlet positioning grid 25 and the outlet positioning grid 26 are provided with positioning holes that match the outer diameter of the heating rods, so as to support and fix the tightly arranged rod bundles and prevent the heating rods from bending and deforming.

[0013] Preferably, the working gas circulating in the experimental apparatus is an inert gas.

[0014] Compared with the prior art, the present invention has the following advantages: 1. The present invention features specially designed inlet and outlet positioning grids at the front and rear ends of the heating section, which effectively supports and fixes the tightly packed bundle of triangular rods, effectively preventing the heating rods from contacting each other and changing the channel shape due to bending deformation under high temperature conditions, thus ensuring the stability of the experimental geometric boundary.

[0015] 2. The present invention adopts an internal temperature measurement scheme, in which the wall temperature measuring thermocouples are respectively built into the inner wall of the corresponding curved heating rods. This successfully solves the problem of difficulty in arranging measuring points in the extremely small gaps of dense rod bundle channels, while avoiding the disturbance of the flow field by external thermocouples. It can realistically simulate the boundary conditions of triangular fuel rod bundles in the reactor and improve the accuracy of experimental data.

[0016] 3. The present invention designs a curved and extended non-heated zone structure. By extending the non-heated area of ​​the heating rod and bending the middle of the non-heated area in two sections, the spacing between the heating rods is increased after leaving the heating area. This provides sufficient space for the curved heating rod outlet joint and sealing structure at the outlet end, effectively solving the sealing problem of dense rod bundle channels under high temperature and high pressure conditions.

[0017] 4. The present invention incorporates an inlet flow equalization plate in the inlet chamber and designs the top of the heating rod as a conical structure. The combination of these two features effectively ensures the uniformity of the incoming flow at the inlet of the dense rod bundle channel, reduces the degree of flow field disturbance when high-temperature gas enters the rod bundle channel, and provides ideal flow field conditions for the study of flow heat transfer characteristics. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the experimental apparatus of the present invention.

[0019] Figure 2 This is a schematic diagram of the dense triangular rod bundle structure of the present invention.

[0020] Figure 3 This is a cross-sectional view of the curved heating rod structure of the present invention.

[0021] Figure 4 This is a schematic diagram of the positioning grid structure of the present invention.

[0022] Figure 5 This is a schematic diagram of the flow equalization orifice plate structure of the present invention.

[0023] Figure 6 This is a cross-sectional view of the experimental apparatus of the present invention.

[0024] Explanation of reference numerals in the attached diagram: 1. Inlet pipe; 2. Inlet chamber; 3. Inlet temperature measuring conduit; 4. Inlet temperature measuring thermocouple; 5. Inlet flange one; 6. Inlet pressure tapping pipe; 7. Heating chamber; 8. Outlet pressure tapping pipe; 9. Outlet flange one; 10. Outlet flange two; 11. Straight pipe section of outlet chamber; 12. Trapezoidal conical section of outlet chamber; 13. Outlet pipe; 14. Outlet temperature measuring conduit one; 15. Outlet temperature measuring thermocouple one; 16. Outlet temperature measuring conduit two; 17. Outlet temperature measuring thermocouple two; 18. Bent heating rod. 19. Outlet connector 1 of the curved heating rod 20. Outlet connector 2 of the curved heating rod 3 21. Curved heating rod 1 22. Curved heating rod 23. Curved heating rod 3 24. Inlet positioning grid 25. Outlet positioning grid 26. Heating area of ​​curved heating rod 1 27. Heating area of ​​curved heating rod 2 28. Heating area of ​​curved heating rod 3 29. Thermocouple for measuring wall temperature of curved heating rod 1 30. Thermocouple for measuring wall temperature of curved heating rod 2 31. Thermocouple for measuring wall temperature of curved heating rod 3 32. Inlet flow equalization orifice plate 33. Detailed Implementation

[0025] To better illustrate the present invention, the accompanying drawings are now provided. Figure 1-6 The present invention will be further described in detail below: like Figure 1 and Figure 6 As shown, this invention provides an experimental apparatus for studying the heat transfer characteristics of a dense triangular rod bundle of high-temperature gas flow, comprising an inlet pipe 1, an inlet chamber 2, an inlet temperature measuring conduit 3, an inlet temperature measuring thermocouple 4, an inlet flange 1, an inlet flange 2, an inlet pressure tapping pipe 7, a heating chamber 8, an outlet pressure tapping pipe 9, an outlet flange 10, an outlet flange 2, an outlet flange 2, a straight pipe section 12 of the outlet chamber, a trapezoidal conical section 13 of the outlet chamber, an outlet pipe 14, an outlet temperature measuring conduit 15, an outlet temperature measuring thermocouple 16, an outlet temperature measuring conduit 2, an outlet temperature measuring thermocouple 2, an outlet temperature measuring thermocouple 2, an outlet heating rod outlet connector 19, an outlet heating rod outlet connector 20, an outlet heating rod outlet connector 3, an outlet heating rod 1, an outlet heating rod 23, an outlet heating rod 3, an inlet positioning grid 25, an outlet positioning grid 26, and an inlet flow equalization orifice plate 33, etc.

[0026] like Figure 1 As shown, inlet pipe 1 connects to the front end of inlet chamber 2 to introduce high-temperature, high-pressure experimental gas. Inlet chamber 2 is connected to heating chamber 8 via inlet flange 5 and inlet flange 6, secured with bolts and nuts at the connection points, and sealed with gaskets to ensure airtightness. The end of heating chamber 8 is connected to straight pipe section 12 of outlet chamber via outlet flange 10 and outlet flange 11, also secured with bolts and sealed with gaskets to ensure airtightness. A trapezoidal conical section 13 of outlet chamber 12 is welded to the rear end of straight pipe section 12, and outlet pipe 14 is connected to the upper side of the end of trapezoidal conical section 13 of outlet chamber 12.

[0027] like Figure 2 and Figure 6 As shown, the heating chamber 8 contains a dense bundle of triangular rods consisting of three bent heating rods: one (22), another (23), and a third (24). The three heating rods are arranged in an equilateral triangle, forming a narrow flow channel to simulate the fuel rod bundle structure in a reactor core. Figure 5 As shown, an inlet flow equalization plate 33 is provided inside the inlet chamber 2. Several through holes are evenly distributed on the plate to ensure that the gas flow field distribution in the rod bundle channel area is uniform and to eliminate the flow field distortion caused by the inlet effect.

[0028] like Figure 3As shown, the bent heating rods 22, 23, and 24 are heated only in specific areas, with the remaining areas being non-heated sections. Specifically, bent heating rod 22 has a first heating area 27, bent heating rod 23 has a second heating area 28, and bent heating rod 24 has a third heating area 29. The bent heating rods 22, 23, and 24 are bent in two sections in the middle of the non-heated section on the right side, so that the spacing between the bent heating rods when they exit the trapezoidal conical section 13 of the oral cavity is greater than their spacing in the heated areas. This design cleverly utilizes the space in the non-heated section, providing ample space for the arrangement and sealing of the end-mounted bent heating rod outlet connectors 19, 20, and 21, effectively solving the technical challenge of sealing dense rod bundle channels under high temperature and high pressure conditions.

[0029] like Figure 3 As shown, this invention employs a built-in temperature measurement scheme. Thermocouple 30 for measuring the wall temperature of the first bent heating rod 22 is built into the inner wall surface of the first bent heating rod 22; thermocouple 31 for measuring the wall temperature of the second bent heating rod 23 is built into the inner wall surface of the second bent heating rod 23; and thermocouple 32 for measuring the wall temperature of the third bent heating rod 24 is built into the inner wall surface of the third bent heating rod 24. All thermocouples are arranged on the side opposite to the bending direction of the corresponding bent heating rod and are positioned and led out close to the inner wall surface. This built-in temperature measurement method avoids the disturbance of the flow field within the narrow channel caused by external thermocouples, enabling a more realistic simulation of the thermal boundary conditions of the fuel rod bundle in a reactor, and significantly improving the accuracy of wall temperature measurement.

[0030] like Figure 4 As shown, the inlet positioning grid 25 is arranged between the inlet pressure tapping pipe 7 and the inlet flange 5, and the outlet positioning grid 26 is arranged between the outlet pressure tapping pipe 9 and the outlet flange 10. The inlet positioning grid 25 and the outlet positioning grid 26 have positioning holes that match the outer diameter of the heating rods, used to support and fix the tightly arranged rod bundles. This structure effectively prevents the slender heating rods from bending and deforming due to thermal expansion or fluid-induced vibration under high-temperature conditions, thus ensuring the stability of the channel geometry and gap dimensions during the experiment.

[0031] like Figure 6 As shown, the inlet temperature measuring conduit 3 is arranged between the inlet flow equalization orifice plate 33 and the inlet flange 5. The inlet temperature measuring thermocouple 4 is installed through this conduit, with its measuring end located at the central axis of the inlet chamber 2, for accurately measuring the inlet gas temperature. The inlet pressure tapping pipe 7 and the outlet pressure tapping pipe 9 are located at the beginning and end positions of the heating zone, respectively. By connecting a differential pressure transmitter, the pressure drop of the gas flowing through the dense rod bundle channel can be accurately measured.

[0032] like Figure 1 and Figure 6 As shown, outlet temperature measuring conduit 15 is positioned below the trapezoidal conical section 13 of the outlet chamber, perpendicular to the central axis of the chamber. Outlet temperature measuring thermocouple 16 passes through this conduit to measure the average mixing temperature at the outlet of the bent heating rod bundle. Outlet temperature measuring conduit 17 is positioned perpendicular to the outlet pipe 14, and outlet temperature measuring thermocouple 18 passes through this conduit to measure the temperature of the final discharged gas. This dual outlet temperature measurement arrangement helps to verify the accuracy of the heat balance calculation.

[0033] In a preferred embodiment of the present invention, the inlet pipe 1, the inlet oral cavity chamber 2, the heating chamber 8, the straight pipe section 12 of the outlet oral cavity chamber, the trapezoidal conical section 13 of the outlet oral cavity chamber, and the outlet pipe 14 are preferably made of high-temperature resistant stainless steel, such as 310S stainless steel. This material has excellent high-temperature oxidation resistance and mechanical strength, and can withstand the high-temperature and high-pressure environment during the experiment, ensuring the structural integrity and service life of the device.

[0034] In a preferred embodiment of the present invention, the three bent heating rods 22, 23, and 24 are preferably made of high-temperature resistant stainless steel, such as 321 stainless steel. This material has good stability at high temperatures and is suitable as a carrier for electric heating elements. The diameter of the bent heating rod is preferably 8-12 mm, and the length of the heating area is preferably 200 mm. In this embodiment, a heating rod diameter of 10 mm is selected, which can meet the experimental power density requirements.

[0035] In a preferred embodiment of the present invention, the arrangement of the dense triangular rod bundle satisfies the condition that the ratio of the center distance of the heating rods to the outer diameter of the heating rods is less than or equal to 1.3, so as to simulate a compact grid structure. In this embodiment, the ratio of the center distance of the heating rods to the outer diameter of the heating rods is 1.15, that is, when the diameter of the heating rods is 10 mm, the center distance of the heating rods is 11.5 mm, and the spacing between the heating rods is only 1.5 mm. This extremely narrow gap design can realistically reproduce the strongly coupled flow heat transfer phenomenon in the dense rod bundle channel.

[0036] In a preferred embodiment of the present invention, the working gas circulating within the experimental apparatus is preferably a mixture of helium and helium-xenon. These gases possess excellent thermophysical properties and are commonly used as coolants in gas-cooled reactors. In this embodiment, by controlling the heating power and gas flow rate, the gas temperature in the outlet pipe can reach 600 degrees Celsius.

[0037] In a preferred embodiment of the present invention, the left ends of the first bent heating rod 22, the second bent heating rod 23, and the third bent heating rod 24 are designed with a conical structure. This structure can effectively reduce the flow field disturbance when high-temperature gas enters the rod bundle channel, reduce the local resistance at the inlet, and allow the fluid to enter the heating section more smoothly.

[0038] The working principle and experimental procedure of the experimental device described in this invention are as follows: High-temperature, high-pressure gaseous working fluid enters the inlet chamber 2 through inlet pipe 1, forming a uniform flow field under the action of inlet flow equalization plate 33. Subsequently, the gas enters the heating chamber 8, flowing through a dense triangular rod bundle channel composed of three curved heating rods. In the heating zone, the gas is heated by the heating rods, and its temperature rises. During this process, the channel pressure drop is measured through inlet pressure taps 7 and outlet pressure taps 9, and fluid temperature and wall temperature data are collected in real time through inlet temperature measuring thermocouple 4, outlet temperature measuring thermocouple 16, and the wall temperature measuring thermocouples (30, 31, 32) built into the three curved heating rods. The heated gas flows out of the rod bundle channel, converges through the trapezoidal conical section 13 of the outlet chamber, and is finally discharged through outlet pipe 14. By analyzing the collected temperature, pressure, and flow rate data, the flow and heat transfer characteristics of the high-temperature gas within the dense triangular rod bundle channel can be obtained.

[0039] The above embodiments are merely illustrative examples of the present invention. The present invention may also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of the present invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

[0040] All content not described in detail in this invention is conventional technical content.

Claims

1. An experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow, characterized in that: Includes inlet pipe (1), inlet chamber (2), inlet temperature measuring conduit (3), inlet temperature measuring thermocouple (4), inlet flange one (5), inlet flange two (6), inlet pressure tapping pipe (7), heating chamber (8), outlet pressure tapping pipe (9), outlet flange one (10), outlet flange two (11), straight pipe section of outlet chamber (12), trapezoidal conical section of outlet chamber (13), outlet pipe (14), outlet temperature measuring conduit one (15), outlet temperature measuring thermocouple one (16), outlet temperature measuring conduit two (17) ), outlet temperature measuring thermocouple 2 (18), curved heating rod outlet connector 1 (19), curved heating rod outlet connector 2 (20), curved heating rod outlet connector 3 (21), curved heating rod 1 (22), curved heating rod 2 (23), curved heating rod 3 (24), inlet positioning grid (25), outlet positioning grid (26), curved heating rod 1 wall temperature measuring thermocouple (30), curved heating rod 2 wall temperature measuring thermocouple (31), curved heating rod 3 wall temperature measuring thermocouple (32), and inlet flow equalization orifice plate (33); The inlet pipe (1) is connected to the front end of the oral cavity chamber (2), and an inlet flow equalization orifice plate (33) is provided inside the oral cavity chamber (2); the inlet temperature measuring conduit (3) is arranged between the inlet flow equalization orifice plate (33) and the inlet flange (5), and the inlet temperature measuring thermocouple (4) is installed through the inlet temperature measuring conduit (3); The inlet end of the heating chamber (8) is connected to the inlet chamber (2) through inlet flange one (5) and inlet flange two (6), and the outlet end is connected to the straight pipe section (12) of the outlet chamber through outlet flange one (10) and outlet flange two (11). The heating chamber (8) is arranged with a dense triangular rod bundle consisting of bent heating rod one (22), bent heating rod two (23) and bent heating rod three (24). The arrangement of the dense triangular rod bundle satisfies the condition that the ratio of the center distance of the heating rod to the outer diameter of the heating rod is less than or equal to 1.3, so as to simulate a compact grid structure. The inlet pressure tapping pipe (7) and the outlet pressure tapping pipe (9) are located at the beginning and end positions of the heating area, respectively. The inlet positioning grid (25) is arranged between the inlet pressure tapping pipe (7) and the inlet flange (5), and the outlet positioning grid (26) is arranged between the outlet pressure tapping pipe (9) and the outlet flange (10). The rear end of the straight pipe section (12) of the oral cavity is connected to the trapezoidal conical section (13) of the oral cavity, and the outlet pipe (14) is connected to the upper side of the end of the trapezoidal conical section (13) of the oral cavity; the first bent heating rod (22), the second bent heating rod (23) and the third bent heating rod (24) pass through the trapezoidal conical section (13) of the oral cavity and are led out through the first bent heating rod outlet connector (19), the second bent heating rod outlet connector (20) and the third bent heating rod outlet connector (21) respectively.

2. The experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow according to claim 1, characterized in that, The first (22), the second (23), and the third (24) of the curved heating rods are heated only in the designated areas, and the remaining areas are non-heated sections. The first (22) of the curved heating rods is provided with a first heating area (27), the second (23) of the curved heating rods is provided with a second heating area (28), and the third (24) of the curved heating rods is provided with a third heating area (29). The first (22), the second (23), and the third (24) of the curved heating rods are bent in two sections in the middle of the non-heated section near the outlet, so that the distance between the curved heating rods when they pass through the trapezoidal conical section (13) of the oral cavity is greater than the distance between them in the heating area.

3. The experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow according to claim 1, characterized in that, The experimental device adopts a built-in temperature measurement scheme. The thermocouple (30) for measuring the temperature of the first wall of the bent heating rod is built into the inner wall of the first bent heating rod (22). The thermocouple (31) for measuring the temperature of the second wall of the bent heating rod is built into the inner wall of the second bent heating rod (23). The thermocouple (32) for measuring the temperature of the third wall of the bent heating rod is built into the inner wall of the third bent heating rod (24). The thermocouples (30), (31), and (32) are all arranged on the side opposite to the bending direction of the corresponding bent heating rod and are arranged and led out close to the inner wall.

4. The experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow according to claim 1, characterized in that, The inlet flow equalization plate (33) has several through holes evenly distributed to ensure that the gas flow field distribution in the rod bundle channel area is uniform; the inlet heads of the first bent heating rod (22), the second bent heating rod (23) and the third bent heating rod (24) are designed as conical structures to reduce the flow field disturbance when the high temperature gas enters the rod bundle channel.

5. The experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow according to claim 1, characterized in that, The first outlet temperature measuring conduit (15) is arranged on the lower side of the trapezoidal conical section (13) of the outlet chamber, perpendicular to the central axis of the cavity. The first outlet temperature measuring thermocouple (16) is arranged through the first outlet temperature measuring conduit (15) and is used to measure the outlet temperature of the bent heating rod bundle. The second outlet temperature measuring conduit (17) is arranged perpendicular to the outlet pipe (14). The second outlet temperature measuring thermocouple (18) is arranged through the second outlet temperature measuring conduit (17) and is used to measure the outlet temperature of the outlet pipe (14).

6. The experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow according to claim 1, characterized in that, The inlet pipe (1), inlet oral cavity (2), heating chamber (8), straight pipe section (12) of outlet oral cavity, trapezoidal conical section (13) of outlet oral cavity, outlet pipe (14), bent heating rod one (22), bent heating rod two (23) and bent heating rod three (24) are made of high temperature resistant stainless steel.

7. The experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow according to claim 1, characterized in that, The inlet flange 1 (5) and the inlet flange 2 (6), and the outlet flange 1 (10) and the outlet flange 2 (11) are all fastened together by bolts and nuts, and a sealing gasket is provided at the connection end face.

8. The experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow according to claim 1, characterized in that, The inlet positioning grid (25) and outlet positioning grid (26) are provided with positioning holes that match the outer diameter of the heating rods, which are used to support and fix the tightly arranged rod bundles and prevent the heating rods from bending and deforming.

9. The experimental apparatus for studying the heat transfer characteristics of dense triangular rod bundles of high-temperature gas flow according to claim 1, characterized in that, The working gas circulating in the experimental apparatus is an inert gas.

10. The experimental method of the experimental apparatus for studying the heat transfer characteristics of a dense triangular rod bundle channel for high-temperature gas flow as described in any one of claims 1 to 9, characterized in that, High-temperature and high-pressure gaseous working fluid enters the inlet chamber (2) through the inlet pipe (1) and forms a uniform flow field under the action of the inlet flow equalization plate (33). Subsequently, the gas enters the heating chamber (8) and flows through the dense triangular rod bundle channel composed of three curved heating rods. In the heating area, the gas is heated by the heating rods and the temperature rises. During this process, the channel pressure drop is measured by the inlet pressure tapping pipe (7) and the outlet pressure tapping pipe (9). Fluid temperature and wall temperature data are collected in real time by the inlet temperature measuring thermocouple (4), the outlet temperature measuring thermocouple (16), and the wall temperature measuring thermocouples built into the three curved heating rods. The heated gas flows out of the rod bundle channel, converges through the trapezoidal conical section (13) of the outlet chamber, and is finally discharged through the outlet pipe (14). By analyzing the collected temperature, pressure, and flow rate data, the flow heat transfer characteristics of the high-temperature gas in the dense triangular rod bundle channel are obtained.

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