A dynamic jet flow cooling experimental device and a testing method

Abstract

The application discloses a dynamic jet flow cooling experimental device and a testing method, and belongs to the technical field of spray cooling, and comprises a nitrogen tank, a high-pressure water storage tank, a booster pump, a water tank, a self-excited oscillation jet flow nozzle, a simulated heat source and a data acquisition system. The nozzle structure with an oscillation cavity and a feedback channel is adopted, the main jet flow enters the nozzle, and a periodic sweeping oscillation jet flow is spontaneously formed by means of the wall attachment effect and the feedback return flow of the fluid itself, and the external mechanical control components, such as the electromagnetic valve, which are prone to mechanical fatigue, are not needed, and the stable pressure liquid supply circulating system of the 'gas-liquid mixed driving' is adopted, the periodic pressure fluctuation generated by the booster pump is absorbed by the gas phase space of the high-pressure water storage tank, and high-pressure long-period and high-stability continuous spraying is realized.

Description

Technical Field

[0001] This invention relates to the field of spray cooling technology, and more particularly to a dynamic jet cooling experimental device. Background Technology

[0002] Currently, common cooling methods for electronic devices include single-phase heat exchange, microchannel cooling, and spray cooling. Traditional single-phase heat exchange methods, such as air and single-phase liquid cooling, are far from meeting the high heat flux density requirements of today's high-performance chips and high-power lasers. The pressure gradient of the cooling medium inside a microchannel is extremely large, and the purity of the fluid is extremely important. If impurities are present, scaling and channel blockage can easily occur, leading to a sharp increase in local temperature and failure.

[0003] Although the traditional continuous spray cooling technology of pressure-type atomizing nozzles performs well in terms of heat dissipation, it still exposes the following core pain points in practical engineering applications: (1) When traditional flat fan-shaped, conical or semi-solid swirl nozzles spray continuously, they are very likely to form a thick stagnant liquid film layer at the center of the jet and the hot surface, which will directly increase the thermal resistance and cause a sharp drop in the local evaporation rate. (2) Static continuous spray is prone to local hot spots at the microscale due to the uneven distribution of droplet momentum, and causes edge drying. (3) The overall weight of traditional systems and complex additional control components, such as solenoid valves that require mechanical control pulses, seriously restrict their application in scenarios with strict requirements for space and weight, such as avionics systems.

[0004] The limitations exposed by existing cooling technologies are fundamentally due to underlying physical mechanisms and structural constraints: traditional single-phase air cooling and water cooling rely solely on fluid convection heat transfer and are constrained by thick boundary layer thermal resistance, resulting in an insurmountable heat flux density ceiling; microchannel cooling, due to extreme microscale effects, results in large flow resistance along the flow path, requires enormous pumping pressure, and has extremely low tolerance for impurities, easily falling into a vicious cycle of "scaling and clogging - local overheating"; and in the field of two-phase heat transfer, traditional continuous spray cooling using static pressure nozzles also faces limitations imposed by inherent flow field characteristics. Due to the lack of effective lateral shear force on the liquid film, the mass input in the central region of the spray is much greater than the discharge, resulting in a large accumulation of coolant and the formation of a thick stagnant liquid film, which significantly increases thermal resistance. At the same time, the spatial distribution of the flow field exhibits a non-uniform distribution with "strong kinetic energy at the center and rapid decay at the periphery," making the edge regions prone to localized drying due to insufficient replenishment of the working fluid. Furthermore, the pulse spray strategy adopted to overcome the above problems must rely on external active mechanical components such as high-frequency solenoid valves, which not only increases the size and complexity of the system, but also makes the mechanical fatigue of its components a bottleneck restricting the reliability of the system. Summary of the Invention

[0005] The purpose of this invention is to provide a dynamic jet cooling experimental device and testing method. It adopts a nozzle structure with an internal oscillation cavity and feedback channel. After the main jet enters, it spontaneously forms a periodic sweeping oscillating jet by relying on the fluid's own wall adhesion effect and feedback backflow. It does not rely on external mechanical control components such as solenoid valves that are prone to mechanical fatigue. It adopts a "gas-liquid mixing driven" pressure-stabilized liquid supply circulation system, which uses the gas phase space of the high-pressure water tank to absorb the periodic pressure fluctuations generated by the booster pump, thereby realizing high-pressure, long-period, and highly stable continuous spraying.

[0006] To achieve the above objectives, the present invention provides a dynamic jet cooling experimental device, comprising a nitrogen tank, a high-pressure water tank, a booster pump, a water tank, a self-excited oscillating jet nozzle, a simulated heat source, and a data acquisition system. The outlet end of the nitrogen tank is connected to the inlet end of the high-pressure water tank, the water tank is connected to the booster pump, the output end of the booster pump is also connected to the inlet end of the high-pressure water tank, the outlet end of the high-pressure water tank is connected to the inlet end of the self-excited oscillating jet nozzle, the outlet end of the self-excited oscillating jet nozzle sprays towards the simulated heat source, and the data acquisition system monitors and acquires the temperature data of the simulated heat source.

[0007] Preferably, the output end of the nitrogen tank is also connected to the inlet end of the high-pressure water storage tank via a pressure reducing valve.

[0008] Preferably, the outlet end of the high-pressure water storage tank is connected to the inlet end of the self-excited oscillating jet nozzle by a valve.

[0009] Preferably, the outlet end of the high-pressure water storage tank and the inlet end of the self-excited oscillating jet nozzle are also connected to a flow meter, a thermometer and a pressure sensor.

[0010] Preferably, the simulated heat source is also electrically connected to a DC power supply.

[0011] Preferably, the self-excited oscillating jet nozzle has an oscillation cavity at its center, and a feedback channel is formed between the inner wall of the self-excited oscillating jet nozzle and the outer wall of the oscillation cavity. The top of the oscillation cavity is connected to the inlet of the feedback channel, and the bottom of the oscillation cavity is also connected to the outlet of the feedback channel.

[0012] Preferably, the nozzle inlet of the self-excited oscillating jet nozzle is connected to the bottom of the oscillation chamber, and the nozzle outlet of the self-excited oscillating jet nozzle is connected to the top of the oscillation chamber.

[0013] Preferably, the bottom inner cavity size of the oscillation cavity is smaller than the top inner cavity size of the oscillation cavity.

[0014] Preferably, the data acquisition system is also electrically connected to a flow meter, a thermometer, and a pressure sensor.

[0015] A test method for a dynamic jet cooling experimental device includes the following steps: Step 1: Connect the nitrogen tank to the high-pressure water tank, adjust the pressure through the pressure reducing valve, and send the cooling medium in the water tank into the high-pressure water tank through the booster pump. The booster pump replenishes the cooling medium into the high-pressure water tank in real time and serves as the main driving force, supplemented by nitrogen pressurization. Step 2: In the spray cooling stage, the high-pressure cooling medium enters the self-excited oscillating jet nozzle from the high-pressure water tank through valves, flow meters, thermometers, and pressure sensors. The high-pressure water tank absorbs the periodic pressure fluctuations generated by the booster pump, thereby ensuring the long-term continuity and stability of the spray cooling process. Step 3: Under stable inlet pressure, when the main jet enters the oscillation chamber through the nozzle inlet, it will adhere to the wall of one side of the oscillation chamber due to the Coanda effect. After the main jet reaches the top of the oscillation chamber, part of the fluid enters the inlet of the feedback channel and flows back to the control throat along the feedback channel, increasing the separation bubble. The increased separation bubble pushes the main jet to develop towards the other side wall of the oscillation chamber, and the cycle repeats, thus forming a periodic oscillating jet at the nozzle with a constant jet velocity and a sweeping oscillation direction within a certain angle range. The cooling medium forms a self-excited oscillating jet in the oscillation chamber and feedback channel inside the nozzle, and is sprayed from the nozzle outlet towards the simulated heat source. Step 4: The simulated heat source is powered by a DC power supply to generate a controllable heat load. The data acquisition system collects and records the temperature changes of the simulated heat source, as well as the data from the flow meter, thermometer, and pressure sensor in real time, for analysis of the cooling effect under different conditions.

[0016] The advantages and positive effects of the dynamic jet cooling experimental device and testing method described in this invention are: 1. The present invention is based on the Coanda effect self-excited oscillating nozzle design. It adopts a nozzle structure with an internal oscillation cavity and feedback channel. After the main jet enters, it spontaneously forms a periodic sweeping oscillating jet by relying on the fluid's own wall adhesion effect and feedback backflow. It does not need to rely on external mechanical control components such as solenoid valves that are prone to mechanical fatigue.

[0017] 2. This invention employs a "gas-liquid hybrid drive" pressure-stabilized liquid supply circulation system. Addressing the critical issue of the self-excited oscillating jet nozzle's extremely high requirement for working pressure stability, this invention constructs a hybrid drive mode combining booster pump liquid supply and nitrogen pressurization. By utilizing the gas phase space of the high-pressure water tank to absorb the periodic pressure fluctuations generated by the booster pump, high-pressure, long-cycle, and highly stable continuous spraying is achieved.

[0018] 3. Addressing the problems exposed by traditional spray cooling technology in practical engineering applications, self-excited swept jet cooling technology exhibits unique advantages due to its unique fluid dynamics characteristics and structural design: First, addressing the problem of excessively thick stagnant liquid films caused by continuous spraying, self-excited swept spray imparts tangential momentum to droplets through the high-speed reciprocating motion of the jet in space. This sweeping process generates periodic shearing and peeling effects on the heated surface, effectively disrupting the thermal boundary layer through strong mechanical disturbance, keeping the liquid film in a very thin dynamic equilibrium state, thereby significantly reducing thermal resistance and improving local evaporative heat transfer efficiency. Second, addressing the problem of uneven droplet momentum distribution in static sprays, the jet outlet of the swept spray is always in a dynamic deflection state. This characteristic enables highly uniform droplet flow distribution in the spray area in the time domain, effectively overcoming the edge drying phenomenon common in static sprays, and significantly reducing the peak temperature gradient and thermal stress concentration of high-power electronic devices under extreme conditions. Third, compared with traditional intermittent sprays that require additional control components, such as solenoid valves, self-excited swept nozzles do not require external control components. It utilizes its internal oscillation chamber and feedback channel, relying on the fluid's own wall adhesion effect, to spontaneously generate periodic sweeping motion. This simple and highly stable design significantly reduces the overall weight and volume of the system.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a dynamic jet cooling experimental device according to the present invention; Figure 2 This is a schematic diagram of the self-excited oscillating jet nozzle structure of the present invention; Figure 3 This is a schematic diagram of the flow direction of the self-excited oscillating jet nozzle of the present invention.

[0021] Figure Labels 1. Nitrogen tank; 2. Pressure reducing valve; 3. High-pressure water tank; 4. Valve; 5. Self-excited oscillating jet nozzle; 6. DC power supply; 7. Simulated heat source; 8. Data acquisition system; 9. Booster pump; 10. Water tank; 11. Flow meter; 12. Thermometer; 13. Pressure sensor; 14. Nozzle inlet; 15. Nozzle outlet; 16. Oscillation chamber; 17. Feedback channel; 18. Feedback channel inlet; 19. Feedback channel outlet. Detailed Implementation

[0022] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any inconsistency, the meaning set forth in this specification or derived from the content described herein shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit the scope of this application.

[0024] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0025] like Figures 1-3 As shown, a dynamic jet cooling experimental device includes a nitrogen tank 1, a high-pressure water tank 3, a booster pump 9, a water tank 10, a self-excited oscillating jet nozzle 5, a simulated heat source 7, and a data acquisition system 8. The outlet end of the nitrogen tank 1 is connected to the inlet end of the high-pressure water tank 3, the water tank 10 is connected to the booster pump 9, the output end of the booster pump 9 is also connected to the inlet end of the high-pressure water tank 3, the outlet end of the high-pressure water tank 3 is connected to the inlet end of the self-excited oscillating jet nozzle 5, and the outlet end of the self-excited oscillating jet nozzle 5 sprays towards the simulated heat source 7. The data acquisition system 8 monitors and collects the temperature data of the simulated heat source 7.

[0026] The output end of nitrogen tank 1 is also connected to the inlet end of high-pressure water storage tank 3 by a pressure reducing valve 2.

[0027] A valve 4 is connected between the outlet end of the high-pressure water storage tank 3 and the inlet end of the self-excited oscillating jet nozzle 5.

[0028] The outlet end of the high-pressure water storage tank 3 and the inlet end of the self-excited oscillating jet nozzle 5 are also connected to a flow meter 11, a thermometer 12 and a pressure sensor 13.

[0029] The simulated heat source 7 is also electrically connected to a DC power supply 6.

[0030] An oscillation cavity 16 is provided in the center of the self-excited oscillation jet nozzle 5. A feedback channel 17 is provided between the inner wall of the self-excited oscillation jet nozzle 5 and the outer wall of the oscillation cavity 16. The top of the oscillation cavity 16 is connected to the inlet 18 of the feedback channel, and the bottom of the oscillation cavity 16 is also connected to the outlet 19 of the feedback channel.

[0031] The nozzle inlet 14 of the self-excited oscillating jet nozzle 5 is connected to the bottom of the oscillation chamber 16, and the nozzle outlet 15 of the self-excited oscillating jet nozzle 5 is connected to the top of the oscillation chamber 16.

[0032] The bottom inner cavity size of the oscillation cavity 16 is smaller than the top inner cavity size of the oscillation cavity 16.

[0033] The data acquisition system 8 is also electrically connected to the flow meter 11, the thermometer 12, and the pressure sensor 13.

[0034] The present invention discloses a testing method for a dynamic jet cooling experimental device, comprising the following steps: Step 1: Connect nitrogen tank 1 to high-pressure water tank 3, adjust the pressure through pressure reducing valve 2, and send the cooling medium in the water tank into high-pressure water tank 3 through booster pump 9. The booster pump 9 replenishes the cooling medium into high-pressure water tank 3 in real time and serves as the main driving force, with nitrogen pressurization as an auxiliary.

[0035] Step 2: In the spray cooling stage, the high-pressure cooling medium enters the self-excited oscillating jet nozzle 5 from the high-pressure water tank 3 through valve 4, flow meter 11, thermometer 12, and pressure sensor 13. The high-pressure water tank 3 absorbs the periodic pressure fluctuations generated by the booster pump, thereby ensuring the long-term continuity and stability of the spray cooling process.

[0036] Step 3: Under stable inlet pressure, when the main jet enters the oscillation chamber 16 through nozzle inlet 14, it adheres to one side of the wall within the oscillation chamber 16 due to the Coanda effect. After reaching the top of the oscillation chamber 16, some fluid enters the feedback channel inlet 18 and flows back to the control throat along the feedback channel, increasing the separation bubble. The increased separation bubble pushes the main jet towards the other side wall of the oscillation chamber 16, repeating the cycle, thus forming a periodic oscillating jet at the nozzle with a constant jet velocity and a sweeping oscillation direction within a certain angle range. The cooling medium forms a self-excited oscillating jet in the oscillation chamber 16 and feedback channel inside the nozzle, and is sprayed from nozzle outlet 15 towards the simulated heat source 7.

[0037] Step 4: The simulated heat source 7 is powered by DC power supply 6 to generate a controllable heat load. The data acquisition system 8 collects and records the temperature change of the simulated heat source 7 and the data from the flow meter 11, thermometer 12 and pressure sensor 13 in real time to analyze the cooling effect under different conditions.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A dynamic jet cooling experimental device, characterized in that: The system includes a nitrogen tank, a high-pressure water tank, a booster pump, a water tank, a self-excited oscillating jet nozzle, a simulated heat source, and a data acquisition system. The outlet of the nitrogen tank is connected to the inlet of the high-pressure water tank, the water tank is connected to the booster pump, the output of the booster pump is also connected to the inlet of the high-pressure water tank, the outlet of the high-pressure water tank is connected to the inlet of the self-excited oscillating jet nozzle, and the outlet of the self-excited oscillating jet nozzle sprays towards the simulated heat source. The data acquisition system monitors and collects the temperature data of the simulated heat source.

2. The dynamic jet cooling experimental device according to claim 1, characterized in that: The output end of the nitrogen tank is also connected to the inlet end of the high-pressure water storage tank by a pressure reducing valve.

3. The dynamic jet cooling experimental device according to claim 2, characterized in that: The outlet end of the high-pressure water storage tank is connected to the inlet end of the self-excited oscillating jet nozzle by a valve.

4. The dynamic jet cooling experimental device according to claim 3, characterized in that: The outlet end of the high-pressure water storage tank is also connected to the inlet end of the self-excited oscillating jet nozzle via a flow meter, a thermometer, and a pressure sensor.

5. The dynamic jet cooling experimental device according to claim 4, characterized in that: The simulated heat source is also electrically connected to a DC power supply.

6. The dynamic jet cooling experimental device according to claim 1, characterized in that: An oscillation chamber is provided at the center of the self-excited oscillating jet nozzle. A feedback channel is provided between the inner wall of the self-excited oscillating jet nozzle and the outer wall of the oscillation chamber. The top of the oscillation chamber is connected to the inlet of the feedback channel, and the bottom of the oscillation chamber is also connected to the outlet of the feedback channel.

7. The dynamic jet cooling experimental device according to claim 6, characterized in that: The nozzle inlet of the self-excited oscillating jet nozzle is connected to the bottom of the oscillation chamber, and the nozzle outlet of the self-excited oscillating jet nozzle is connected to the top of the oscillation chamber.

8. The dynamic jet cooling experimental device according to claim 7, characterized in that: The bottom inner cavity of the oscillation cavity is smaller than the top inner cavity of the oscillation cavity.

9. The dynamic jet cooling experimental device according to claim 1, characterized in that: The data acquisition system is also electrically connected to a flow meter, thermometer, and pressure sensor.

10. The test method of the dynamic jet cooling experimental device as described in any one of claims 1-9, characterized in that: Includes the following steps, Step 1: Connect the nitrogen tank to the high-pressure water tank and adjust the pressure through the pressure reducing valve. The cooling medium in the water tank is sent into the high-pressure water tank by the booster pump. The booster pump replenishes the cooling medium into the high-pressure water tank in real time and serves as the main driving force, supplemented by nitrogen pressurization. The high-pressure water tank absorbs the periodic pressure fluctuations generated by the booster pump, thereby ensuring the long-term continuity and stability of the spray cooling process. Step 2: In the jet cooling stage, the high-pressure cooling medium enters the self-excited oscillating jet nozzle from the high-pressure water tank through valves, flow meters, thermometers, and pressure sensors; Step 3: Under stable inlet pressure, when the main jet enters the oscillation chamber through the nozzle inlet, it will adhere to the wall of one side of the oscillation chamber under the action of the fluid Coanda effect. After the main jet reaches the top of the oscillating cavity, some fluid enters the inlet of the feedback channel and flows back to the control throat along the feedback channel, increasing the separation bubble; the increased separation bubble pushes the main jet to develop towards the other side wall of the oscillating cavity, repeating the cycle, thus forming a periodic oscillating jet at the nozzle with a constant jet velocity and a jet direction that sweeps and oscillates within a certain angle range; The cooling medium forms a self-excited oscillating jet in the oscillation chamber and feedback channel inside the nozzle, and is sprayed from the nozzle outlet toward the simulated heat source; Step 4: The simulated heat source is powered by a DC power supply to generate a controllable heat load. The data acquisition system collects and records the temperature changes of the simulated heat source, as well as the data from the flow meter, thermometer, and pressure sensor in real time, for analysis of the cooling effect under different conditions.

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