Low-flow-resistance jet spray type liquid cooling low-temperature gas supply device and application thereof

Abstract

The invention belongs to the technical field of fluid mixing heat exchange, and particularly relates to a low-flow-resistance jet spray type liquid cooling low-temperature gas supply device and application thereof. Comprising a gas diversion system and a liquid supply system; the gas diversion system comprises a pre-cooling pipeline and a hemispherical diversion structure arranged in the pre-cooling pipeline; the precooling pipeline comprises an air inlet and an air outlet; the liquid supply system is arranged around the gas inlet end of the pre-cooling pipeline, communicates with the pre-cooling pipeline through a nozzle system arranged in the circumferential direction and is used for spraying liquid nitrogen into the pre-cooling pipeline so as to cool gas to be cooled; the hemispherical flow guide structure is arranged at the air inlet end of the pre-cooling pipeline, and the spherical face side of the hemispherical flow guide structure faces the air inlet and is used for guiding sprayed liquid nitrogen. In the working process, the temperature uniformity and the total pressure recovery coefficient are high, and the temperature distortion rate is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid mixing heat exchange, and in particular relates to a low-flow-resistance jet spray type liquid-cooled low-temperature gas supply device and an application thereof. Background Art

[0002] Among existing technologies, liquid nitrogen spray jet cooling technology remains one of the best solutions for cryogenic gas supply in cryogenic wind tunnels to achieve rapid pre-cooling of gases. For example, the liquid nitrogen supply system studied by Zhang Wei et al. (Development of a Liquid Nitrogen Supply System for a 0.3m Cryogenic Wind Tunnel [J]. Journal of Aerospace Power, 2020, 35(05):1009-1017) ensures precise control of the total temperature of the wind tunnel gas by adjusting the number of nozzle starts and stops and the injection pressure. Ruan Yixiao et al. (Study on the Evaporation Motion Characteristics of Single Liquid Nitrogen Droplets in Air Flow [J]. Journal of Xi'an Jiaotong University, 2017, 51(06):147-152) studied the evaporation model of nitrogen droplets in high-speed airflow and studied the laws of liquid nitrogen jet spray cooling technology at the microscopic level, providing a basis for the optimization of jet spray liquid cooling devices.

[0003] While existing jet spray precooling technology can improve heat transfer efficiency, it still suffers from issues such as uneven droplet distribution, insufficient evaporation, localized overheating, and sudden changes in flow resistance. Furthermore, the traditional liquid nitrogen spray method suffers from unstable heat transfer and large fluctuations in flow resistance due to the difficulty in controlling the phase change process and uneven gas-liquid mixing, making it difficult to meet the high airflow quality requirements of cryogenic wind tunnels.

[0004] Therefore, there is an urgent need for a liquid spray precooling technology that can achieve uniform mixing of gas and liquid, improve heat exchange efficiency and reduce flow resistance, so as to meet the demand for high-performance gas precooling devices in low-temperature wind tunnels and other occasions.

[0005] High-efficiency heat exchange and low-resistance jet pre-cooling technology achieves uniform mixing of the gas and liquid phases by designing and arranging the flow channel structure and setting up multiple nozzles evenly distributed. This technology is often used to provide low-temperature gases in low-temperature wind tunnels. Existing technologies use jet pre-cooling technology to directly contact high-temperature gases with atomized liquids (such as water or refrigerants). While this improves heat exchange efficiency, problems such as uneven droplet distribution and incomplete evaporation can easily lead to local overheating or a sudden increase in flow resistance. Traditional jet injection methods for low-temperature liquids face difficulties in controlling the phase change process and uneven gas-liquid mixing, resulting in limited heat exchange efficiency and significant fluctuations in flow resistance.

[0006] Clearly, given the significant demand for cryogenic liquid jet pre-cooling in cryogenic wind tunnel experiments, there is still considerable room for improvement in jet pre-cooling technology. Achieving uniform mixing of the gas and liquid phases is a key issue limiting the application of high-efficiency heat transfer and low-resistance jet pre-cooling in cryogenic wind tunnels. Summary of the Invention

[0007] The purpose of the present invention is to provide a low-resistance jet spray type liquid-cooled low-temperature gas supply device and its application, which improves the gas-liquid mixing uniformity and heat exchange effect through a hemispherical guide structure.

[0008] To achieve the above-mentioned object, the present invention provides a low-resistance jet spray type liquid-cooled low-temperature gas supply device, comprising a gas guide system and a liquid supply system;

[0009] The gas guide system includes a pre-cooling pipe and a hemispherical guide structure arranged in the pre-cooling pipe; the pre-cooling pipe includes an air inlet and an air outlet;

[0010] The liquid supply system is arranged around the air inlet end of the pre-cooling pipe and is connected to the pre-cooling pipe through a circumferentially arranged nozzle system, and is used to spray liquid nitrogen into the pre-cooling pipe to cool the gas to be cooled;

[0011] The hemispherical guide structure is arranged at the air inlet end of the pre-cooling pipe, with one side of the spherical surface facing the air inlet, and is used to guide the injected liquid nitrogen.

[0012] Furthermore, the center of the hemispherical flow-guiding structure is collinear with the axis of the pre-cooling pipe, and the diameter of the hemispherical flow-guiding structure is smaller than the inner diameter of the pre-cooling pipe.

[0013] Furthermore, the hemispherical guide structure is a hollow hemispherical structure, and the material is molybdenum-tungsten alloy.

[0014] Furthermore, the hemispherical guide structure is fixed in the pre-cooling pipe through a support rod.

[0015] Furthermore, the pre-cooling pipe includes a gas-liquid guide section, a flow stabilizing section and a gas-liquid separation section, which are sequentially arranged on one side of the plane of the hemispherical guide structure. The inner diameters of the gas-liquid guide section and the gas-liquid separation section are the same, and the inner diameter of the flow stabilizing section is smaller than the inner diameters of the gas-liquid guide section and the gas-liquid separation section to form an annular groove.

[0016] Furthermore, the liquid supply system includes a liquid nitrogen collecting ring arranged around the air inlet end of the pre-cooling pipe, and a plurality of spray holes are evenly distributed circumferentially on the inner wall of the liquid nitrogen collecting ring. The outer side of each spray hole is connected to a nozzle of the nozzle system, and the outer circumference of the pre-cooling pipe is provided with a liquid inlet hole corresponding to each nozzle.

[0017] Furthermore, the liquid nitrogen collecting ring includes a liquid guide tube and a liquid insulation layer covering the outer peripheral wall of the liquid guide tube, the spray hole is arranged on the inner peripheral wall of the liquid guide tube, and the liquid guide tube is provided with a liquid nitrogen inlet.

[0018] Furthermore, the jet direction of each nozzle forms an angle of 25-35° with the radial direction of the outer wall of the pre-cooling pipe where the nozzle is located.

[0019] Furthermore, the number of the nozzle holes is 8-12, and the liquid nitrogen sprayed from the nozzle is droplets with a diameter of 10 to 100 μm.

[0020] Furthermore, the nozzle diameter satisfies the following relationship:

[0021]

[0022] Where d is the droplet diameter, d0 is the nozzle diameter, ρ a is the gas density in the spray chamber, ΔP is the pressure difference between the inside and outside of the nozzle, σ is the surface tension of the liquid, μ f is the dynamic viscosity of the liquid.

[0023] The present invention also provides a low-temperature wind tunnel system, comprising the low-flow-resistance jet spray type liquid-cooled low-temperature gas supply device described in any one of the above items.

[0024] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0025] The low-resistance jet spray-type liquid-cooled cryogenic gas supply device provided by this invention features a hemispherical flow guide structure within the nozzle jet area, effectively directing the atomized liquid jet to cover the central area of the pipe, thereby avoiding high temperatures at the center of the outlet section caused by blind spots. The mechanical and thermal stresses of this structure are both lower than the material strength, meeting safety requirements.

[0026] 2. An annular groove is set downstream of the guide structure to replace the traditional baffle to avoid thermal stress concentration caused by welding of dissimilar materials. At the same time, the gas-liquid mixing is enhanced by inducing turbulence, further alleviating the thermal stress problem caused by the high temperature difference near the wall.

[0027] 3. This invention arranges 12 nozzle headers circumferentially around the liquid inlet section of the pre-cooling pipeline and connects them to the nozzle system. This ensures sufficient liquid supply while fully considering the difficulty of pressure regulation. By increasing the number of nozzles, the coverage and uniformity of the jet flow are improved, significantly reducing liquid pressure fluctuations and effectively improving the uniformity of temperature distribution during the gas pre-cooling process.

[0028] 4. The nozzle female head features a tapered boss threaded hole structure, located on the outer wall of the pipe. The hole axis is deflected 30° circumferentially, achieving orderly deflection of the spray direction. This design helps improve the spatial distribution of the spray, reduce the temperature distortion rate, and increase the total pressure recovery coefficient, thereby enhancing flow organization and heat transfer stability.

[0029] 5. The present invention adopts a split liquid nitrogen collecting ring with a double-layer vacuum structure, which can achieve uniform distribution of liquid before injection, enhance the flow consistency and synergistic effect between nozzles, thereby improving the overall heat exchange efficiency and operational reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic cross-sectional view of a low-resistance jet spray type liquid-cooled low-temperature gas supply device provided in an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram on the left side of a low-resistance jet spray type liquid-cooled low-temperature gas supply device provided in an embodiment of the present invention.

[0032] Figure 3 Schematic diagram of the structure of the pre-cooling pipe at different angles provided by an embodiment of the present invention.

[0033] Figure 4 Schematic diagrams of the structure of the hemispherical guide structure at different angles provided by an embodiment of the present invention.

[0034] Figure 5 Schematic diagram of the structure of the liquid nitrogen collecting ring at different angles provided by an embodiment of the present invention.

[0035] Figure 6 Schematic diagram of the simulation results of temperature changes in the pipeline under different gas-liquid ratios of the low-flow resistance jet spray liquid-cooled low-temperature gas supply device provided by an embodiment of the present invention.

[0036] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0037] 1- Pre-cooling pipe; 2- Liquid nitrogen collecting ring; 3- Hemispherical guide structure; 4- Nozzle system; 5- Gas-liquid guide section; 6- Flow stabilization section; 7- Gas-liquid separation section; 8- Liquid insulation layer; 9- Liquid guide pipe. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0039] See also Figure 1-6 The present invention provides a pre-spray jet cooling device for a liquid supply system, comprising a gas flow guide system and a liquid supply system. Specifically, the device comprises a pre-cooling pipe 1, a liquid nitrogen collecting ring 2, a hemispherical flow guide structure 3, and a nozzle system 4.

[0040] The gas guide system includes a pre-cooling pipe 1 and a hemispherical guide structure 3 arranged in the pre-cooling pipe 1; the pre-cooling pipe 1 includes an air inlet and an air outlet respectively arranged at both ends.

[0041] The liquid supply system is arranged around the air inlet end of the pre-cooling pipe 1 and is connected to the pre-cooling pipe 1 through a circumferentially arranged nozzle system 4, and is used to spray liquid nitrogen into the pre-cooling pipe 1 to cool the gas to be cooled;

[0042] The hemispherical guide structure 3 is arranged at the air inlet end of the pre-cooling pipe 1, with one side of the spherical surface facing the air inlet, for guiding the injected liquid nitrogen.

[0043] Liquid is distributed from an external supply system through a liquid nitrogen collecting ring 2 to each nozzle, where it is sprayed into the pre-cooling pipe 1 as a high-speed jet. High-temperature air flows into the pre-cooling pipe 1 from the air inlet. As it passes through the pre-cooling pipe 1, it is guided by the hemispherical guide structure 3, which disperses the central airflow and fully mixes it with the liquid jet, achieving rapid and uniform cooling.

[0044] like Figure 1 The precooling pipe 1 includes a gas-liquid guide section 5, a flow stabilization section 6, and a gas-liquid separation section 7 (for evaporating liquid nitrogen into nitrogen gas), sequentially arranged on one side of the plane of the hemispherical flow guide structure 3. The gas-liquid guide section 5 and the gas-liquid separation section 7 have the same inner diameter, and the inner diameter of the flow stabilization section 6 is smaller than that of the gas-liquid guide section 5 and the gas-liquid separation section 7, forming an annular groove. This serves as an annular baffle to further disturb the airflow, enhance mixing, alleviate high temperatures near the wall, and reduce the temperature gradient near the wall. The cooled mixed gas is discharged through the outlet of the precooling pipe 1.

[0045] The pre-cooling pipe 1 is a straight cylindrical structure, divided into a high-temperature section and a low-temperature section. The high-temperature section includes a gas-liquid diversion section 5 and a flow stabilization section 6, and the low-temperature section includes a gas-liquid separation section 7. The high-temperature section is made of ultra-high-temperature ceramic-based composite materials, while the low-temperature section is made of high-temperature alloys.

[0046] like Figure 1 and 4A hemispherical flow guide structure 3, made of tungsten-molybdenum alloy, is installed at the center of the precooling pipe 1. This structure is used to uniformly guide the jetting liquid and prevent high temperatures at the center caused by the liquid not being able to reach the center. The hemispherical structure is hollow and made of molybdenum-tungsten alloy. Three rods made of the same material are welded together and bolted to the outside of the precooling pipe via three small central openings. The installation position is determined by the three small central openings on the outer wall of the precooling pipe 1. The axial installation position along the precooling pipe 1 is determined by the three small central openings on the outer wall of the precooling pipe 1. The radial installation position along the precooling pipe 1 is determined by the curved bosses on the three support rods and threaded bolts on the inner and outer walls of the pipe, respectively. In an environment where liquid cools high-temperature air, the hemispherical flow guide structure 3 is subject to large temperature gradients. This uneven temperature or inconsistent thermal expansion coefficient can cause thermal stress and deformation. The hemispherical structure is made of tungsten-molybdenum alloy. Thermal stress analysis has shown that its yield strength and deformation meet the requirements.

[0047] The hemispherical flow guide structure 3 can achieve complete evaporation of the liquid in the pipe section at the maximum flow rate through the combined effect of the annular baffle of the pre-cooling pipe 1.

[0048] like Figure 5 A liquid nitrogen collection ring 2 is installed outside the pre-cooling pipe 1. It features a split, semi-ring structure connected via flanges. The liquid nitrogen collection ring 2 is a double-layered, semi-ring vacuum structure consisting of a liquid insulation layer 8 and a liquid flow conduit 9. Each semi-ring has a flange structure at its base for interconnection. The liquid inlet of each semi-ring is located directly in front of the center of the semi-ring. A circumferential nozzle connector is threadedly connected to the nozzle system 4, distributing liquid to the nozzle system 4 and improving the uniformity and consistency of the nozzle system's jet flow.

[0049] The liquid guide tube 9 features 12 female connectors (spray holes) arranged in a single, evenly spaced ring around the circumference. The female connectors are circumferentially deflected 16.38°, corresponding to the tapered holes in the pre-cooling pipe 1. These connectors are designed as tapered bosses with threaded holes, while the male connectors are threaded into the female connectors. Once installed, the nozzle tip extends into the pre-cooling pipe 1 (the spray bar is positioned outside the pipe to prevent liquid evaporation from affecting the pre-cooling effect and improve the total pressure recovery coefficient). Droplets of 10 to 100 μm are sprayed into the pre-cooling pipe 1 via the nozzles. Simultaneously, the gas to be cooled is introduced into the pre-cooling pipe's air inlet. The hemispherical guide structure 3 ensures uniform mixing of the liquid spray with the gas within the flow field, achieving gas pre-cooling. The jet direction of the nozzle system 4 forms a 30° angle with the radial direction of the outer wall of the pre-cooling pipe 1, where the nozzle is located, to achieve better temperature uniformity and lower flow resistance, enhancing the mixing efficiency of the liquid and high-temperature gas.

[0050] The nozzle type is a 90° conical nozzle, and considering its size, a total of 12 nozzles are selected to form a nozzle system, so as to obtain evenly distributed spray particles and improve jet uniformity.

[0051] The nozzle diameter satisfies the following relationship:

[0052]

[0053] Where d is the droplet diameter, unit is m; d0 is the nozzle diameter, unit is m; ρ a is the gas density in the spray chamber, unit: kg / m 3 ; ΔP is the pressure difference between the inside and outside of the nozzle, unit is Pa; σ is the surface tension of the liquid, unit is N / m; μ f is the dynamic viscosity of the liquid, in Pa·s.

[0054] The gap between the nozzle and the conical surface of the pre-cooling pipe 1 is sealed with alumina fiber felt. The fiber felt has both sealing and thermal insulation properties, effectively isolating the direct heat exchange between the high-temperature airflow and the nozzle, reducing liquid evaporation.

[0055] In summary, the present invention achieves efficient heat exchange and low flow resistance characteristics by optimizing the structure of the pre-cooling pipe 1, the layout of the hemispherical guide structure 3 and the nozzle angle. The combined design of the annular baffle and the circumferential deflection nozzle effectively solves the problems of high temperature in the center and heat accumulation near the wall; the tungsten-molybdenum alloy material and the split liquid collecting ring structure take into account both high temperature resistance and ease of installation. The present invention can ultimately achieve a higher temperature uniformity and total pressure recovery coefficient, as well as a lower temperature distortion rate during operation of the pre-cooling device. It solves the key problem of insufficient temperature uniformity in the nitrogen jet pre-cooling system of the low-temperature wind tunnel, and provides a new and effective way to improve the temperature uniformity of the jet pre-cooling technology used in transonic low-temperature wind tunnels.

[0056] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low flow resistance jet spray type liquid cooling low temperature gas supply device, characterized in that: Including gas diversion system and liquid supply system; The gas guide system includes a pre-cooling pipe and a hemispherical guide structure arranged in the pre-cooling pipe; the pre-cooling pipe includes an air inlet and an air outlet; The liquid supply system is arranged around the air inlet end of the pre-cooling pipe and is connected to the pre-cooling pipe through a circumferentially arranged nozzle system, and is used to spray liquid nitrogen into the pre-cooling pipe to cool the gas to be cooled; The hemispherical guide structure is arranged at the air inlet end of the pre-cooling pipe, with one side of the spherical surface facing the air inlet, and is used to guide the injected liquid nitrogen.

2. The low flow resistance jet spray type liquid cooling low temperature gas supply device according to claim 1, characterized in that: The center of the hemispherical flow-guiding structure is collinear with the axis of the pre-cooling pipe, and the diameter of the hemispherical flow-guiding structure is smaller than the inner diameter of the pre-cooling pipe.

3. The low flow resistance jet spray type liquid cooling low temperature gas supply device according to claim 1, characterized in that: The hemispherical guide structure is a hollow hemispherical structure made of molybdenum-tungsten alloy; And / or, the hemispherical guide structure is fixed in the pre-cooling pipe via a support rod.

4. The low flow resistance jet spray type liquid cooling low temperature gas supply device according to any one of claims 1 to 3, characterized in that: The pre-cooling pipe includes a gas-liquid guide section, a flow stabilizing section and a gas-liquid separation section, which are sequentially arranged on one side of the plane of the hemispherical guide structure. The inner diameters of the gas-liquid guide section and the gas-liquid separation section are the same, and the inner diameter of the flow stabilizing section is smaller than the inner diameters of the gas-liquid guide section and the gas-liquid separation section to form an annular groove.

5. The low flow resistance jet spray type liquid cooling low temperature gas supply device according to any one of claims 1 to 3, characterized in that: The liquid supply system includes a liquid nitrogen collecting ring arranged around the air inlet end of the pre-cooling pipe, and a plurality of spray holes are evenly distributed circumferentially on the inner wall of the liquid nitrogen collecting ring. The outer side of each spray hole is connected to a nozzle of the nozzle system, and the outer circumference of the pre-cooling pipe is provided with a liquid inlet hole corresponding to each nozzle.

6. The low flow resistance jet spray type liquid cooling low temperature gas supply device according to claim 5, characterized in that: The liquid nitrogen collecting ring includes a liquid guide tube and a liquid insulation layer covering the outer peripheral wall of the liquid guide tube. The spray hole is arranged on the inner peripheral wall of the liquid guide tube. The liquid guide tube is provided with a liquid nitrogen inlet.

7. The low flow resistance jet spray type liquid cooling low temperature gas supply device according to claim 5, characterized in that: The jet direction of each nozzle forms an angle of 25-35° with the radial direction of the outer wall of the pre-cooling pipe where the nozzle is located.

8. The low flow resistance jet spray type liquid cooling low temperature gas supply device according to claim 5, characterized in that: The number of the nozzle holes is 8-12, and the liquid nitrogen sprayed from the nozzle is droplets with a diameter of 10-100 μm.

9. The low flow resistance jet spray type liquid cooling low temperature gas supply device according to claim 8, characterized in that: The nozzle diameter satisfies the following relationship: Where d is the droplet diameter, d0 is the nozzle diameter, ρ a is the gas density in the spray chamber, ΔP is the pressure difference between the inside and outside of the nozzle, σ is the surface tension of the liquid, μ f is the dynamic viscosity of the liquid.

10. A low temperature wind tunnel system, characterized in that: It comprises the low flow resistance jet spray type liquid-cooled low-temperature gas supply device according to any one of claims 1 to 9.

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