Gas phase temperature measurement probe for high-speed low-temperature cloud field and its design method and application

Abstract

This invention relates to the field of flow field temperature testing technology, specifically to a gas phase temperature measurement probe for high-speed, low-temperature cloud and fog fields, its design method, and its application. The design method for this gas phase temperature measurement probe for high-speed, low-temperature cloud and fog fields includes the following steps: First, based on the backward temperature measurement probe configuration, combined with the backward step two-phase flow theory in the backward temperature measurement probe configuration and the operating conditions of the high-speed, low-temperature cloud and fog field, the temperature measurement probe configuration is designed; second, based on the temperature measurement probe configuration, two-phase flow simulation and suction flow simulation are performed to design the suction flow rate; next, icing numerical simulation is conducted, and two-phase flow simulation is performed; finally, the simulation results of the near-wall flow field change of the temperature measurement probe configuration after icing and the simulation results of the gas-liquid flow characteristics are analyzed. If no droplets are detected at the detection position of the temperature sensing element in the icing temperature measurement probe configuration, the design is complete; otherwise, the above steps are repeated until no droplets are detected at the detection position of the temperature sensing element in the icing temperature measurement probe configuration.

Description

Technical Field

[0001] This invention relates to the field of flow field temperature testing technology, specifically to a gas phase temperature probe for high-speed low-temperature cloud and fog fields, its design method, and its application. Background Technology

[0002] Conducting simulated icing cloud and fog environment experiments using icing wind tunnels is crucial for researching and evaluating the icing characteristics of engines and aircraft. However, accurately simulating high-altitude icing cloud and fog environments presents challenges across many fields, and numerous technical difficulties remain to be overcome. Measurement of two-phase flow field parameters is a key aspect. Airflow temperature is a crucial parameter in two-phase flow field parameter measurement, quantifying the inertia and thermal energy of the flow and characterizing the state of the gas-liquid two-phase flow. Airflow temperature also influences the impact icing characteristics of supercooled droplets and is an important parameter in icing experiments. In the high-speed, low-temperature two-phase flow generated in icing wind tunnels, the gas phase flow field and the diffusion and distribution characteristics of droplet swarms are more complex and variable, making the heat transfer process between airflow, droplets, and ice crystals more difficult to predict. Therefore, accurate measurement of gas phase temperature is essential for research on icing mechanisms and anti-icing / de-icing technologies.

[0003] In experiments conducted in icing wind tunnels, the complex low-temperature cloud and fog environment restricts the use of conventional temperature measurement methods. The large number of supercooled droplets entrained in the incoming flow prevents temperature sensing elements from directly measuring the temperature of the pure airflow; simultaneously, the icing characteristic of supercooled droplets impacting the walls further limits the use of temperature sensing elements. Current research on cloud and fog field parameter measurement techniques in icing wind tunnels, both domestically and internationally, mainly focuses on droplet parameters such as MVD and LWC, or other airflow parameters under two-phase conditions; research on gas phase temperature measurement methods in low-temperature gas-liquid two-phase flow environments is still insufficient, and there is no mature method to eliminate the interference from supercooled droplets in the cloud and fog field of icing wind tunnels during temperature measurement.

[0004] As can be seen from the current development status of gas phase temperature measurement probes for gas-liquid two-phase flow, current research focuses on designing temperature measurement probes capable of separating the gas and liquid phases of the incoming flow, due to the relative accuracy and faster response of contact temperature measurement methods. Some domestic research has been conducted in this area, but the results are only applicable to low-speed, ambient-temperature gas-liquid two-phase flow environments such as rain zones, and cannot be used in low-temperature, high-speed cloud and fog fields within icing wind tunnels. International institutions such as NASA have designed and tested temperature measurement probes based on icing wind tunnel conditions, but these probes all suffer from problems such as incompatible applicable operating conditions and large temperature measurement errors. Therefore, research is needed on the design of gas phase temperature measurement probes for high-speed, low-temperature cloud and fog fields, based on the operating conditions of domestic icing wind tunnels.

[0005] Among existing two-phase flow temperature probes, the backward temperature probe (RFP) has been tested in icing wind tunnel experiments, and the results show that this structure has a certain gas-liquid separation effect. However, there is limited data on this probe, and its specific structural dimensions, design concept, and actual application are still unclear. Furthermore, the wind speed range in domestic icing wind tunnels is 50-160 m / s, while this temperature probe only passed the test under conditions where the air velocity is higher than 80 m / s and the relative humidity is lower than 35%, meaning its applicable operating conditions do not cover all conditions in domestic icing wind tunnels. Therefore, based on this probe, a redesign was carried out to optimize the design concept, clarify and expand the applicable operating conditions, and optimize the gas-liquid separation effect, ultimately obtaining a temperature probe suitable for the operating conditions of domestic icing wind tunnels. Summary of the Invention

[0006] The purpose of this invention is to provide a design method for a gas phase temperature probe for high-speed low-temperature cloud and fog fields, so as to solve the problems of poor gas-liquid separation effect and limited applicable working conditions of the back-side temperature probe in the prior art.

[0007] To address the aforementioned problems, this invention proposes a design method for a gas phase temperature measurement probe used in high-speed, low-temperature cloud and fog fields. The technical solution adopted is as follows:

[0008] The design method for a gas phase temperature measurement probe for high-speed, low-temperature cloud and fog fields includes the following steps:

[0009] S1. Based on the backward temperature probe configuration, combined with the backward step two-phase flow theory in the backward temperature probe configuration and the working conditions of high-speed low temperature cloud fog field, the gas-liquid separation structure configuration of the backward temperature probe is designed, and the temperature probe configuration is obtained. The temperature probe configuration is provided with a temperature sensing element detection position.

[0010] S2, based on the temperature probe configuration, performs two-phase flow simulation and suction flow simulation to realize the simulation of gas-liquid flow characteristics caused by the suction flow of the temperature probe configuration in the two-phase flow field, and analyzes the simulation results to obtain relevant data of droplets in the gas and liquid entering the temperature probe configuration.

[0011] S3, Analyze the relevant data of the droplets in the gas and liquid entering the temperature probe configuration. If no droplets are detected at the detection position of the temperature sensing element in the temperature probe configuration, the design of the suction flow rate of the temperature probe configuration is completed, and proceed to the next step.

[0012] Otherwise, repeat the suction flow simulation in step S2 until no droplets are detected at the temperature sensing element detection position in the temperature probe configuration;

[0013] S4. Perform icing numerical simulation on the temperature probe configuration to obtain the reconstructed geometric model of the icing temperature probe configuration. Based on the reconstructed geometric model of the icing temperature probe configuration, perform two-phase flow simulation. Combined with the suction flow rate of the designed temperature probe configuration, realize the simulation of the near-wall flow field change and gas-liquid flow characteristics caused by the icing temperature probe configuration in the two-phase flow field.

[0014] S5, analyze the simulation results of the near-wall flow field change caused by the icing temperature probe configuration in the two-phase flow field and the simulation results of the gas-liquid flow characteristics, and obtain the relevant data of the liquid droplets in the gas and liquid entering the icing temperature probe configuration.

[0015] S6, Analyze the relevant data of liquid droplets in the gas and liquid in the temperature probe configuration after freezing. If no droplets are detected at the detection position of the temperature sensing element in the temperature probe configuration after freezing, the design is complete.

[0016] Otherwise, repeat steps S1-S5 until no droplets are detected at the temperature sensing element detection position in the frozen temperature probe configuration.

[0017] Furthermore, in S1, the gas-liquid separation structure configuration of the temperature measuring probe, based on the backward temperature probe configuration and combined with the backward step two-phase flow theory and the high-speed low-temperature cloud fog field conditions, specifically includes:

[0018] Based on the backward temperature probe configuration, and combined with the motion state of droplets in the gas flow during the backward step two-phase flow in the backward temperature probe configuration, and based on the droplet size and velocity, the maximum backward step height in the gas-liquid separation structure configuration of the temperature probe is calculated, and thus the gas-liquid separation structure configuration of the temperature probe is obtained.

[0019] Further, in S4, the icing numerical simulation includes: calculating the airflow field based on the initial grid and combining it with the droplet impact calculation to obtain the icing calculation of the temperature probe wall, realizing the boundary reconstruction of the icing model, and thus obtaining the reconstructed geometric model of the temperature probe configuration after icing; at the same time, determining whether the icing time in the icing numerical simulation process reaches the set temperature probe configuration usage time, if it does, the simulation ends; otherwise, repeating the above icing numerical simulation steps until the icing time in the icing numerical simulation process reaches the set temperature probe configuration usage time.

[0020] Furthermore, in S4, the two-phase flow simulation based on the reconstructed geometric model of the icing-out temperature probe configuration, combined with the suction flow rate of the designed temperature probe configuration, specifically includes: in the two-phase flow simulation, based on the suction flow rate of the designed temperature probe configuration, and the shear layer and separation vortex of the droplets flowing in the near-wall flow field of the icing-out temperature probe configuration, the LES-WALE turbulence model is used to simulate and calculate the near-wall flow field of the icing-out temperature probe configuration.

[0021] Furthermore, the LES-WALE turbulence model includes a large eddy model and a WALE model. The large eddy model is used to model and calculate the large eddies in the separated eddies while modeling the small eddies in the separated eddies. The WALE model is used to optimize the simulation calculation of the near-wall flow field of the icing temperature probe configuration and to correct the turbulent viscosity of the shear layer.

[0022] Furthermore, in S5, the simulation results of the near-wall flow field changes and gas-liquid flow characteristics caused by the icing-out temperature probe configuration in the two-phase flow field also include: acquiring and analyzing the flow field diagram of the icing-out temperature probe configuration; if there is no disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration, then continue to analyze the relevant data of droplets in the gas and liquid entering the icing-out temperature probe configuration, and determine whether droplets are detected at the temperature sensing element detection position in the icing-out temperature probe configuration; if there is a disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration, then repeat steps S1-S4 until there is no disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration.

[0023] Furthermore, the design method for the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields also includes: after S6, performing strength verification on the designed temperature measurement probe configuration. The strength verification of the designed temperature measurement probe configuration specifically includes: simulating the time-averaged flow field of the temperature measurement probe configuration at 160 m / s, extracting the pressure distribution results on the wall of the temperature measurement probe configuration, performing transient stress calculation and equivalent stress calculation based on the pressure distribution results on the wall of the temperature measurement probe configuration, evaluating the stress results of the temperature measurement probe, and then determining whether the structural strength of the temperature measurement probe meets the requirements.

[0024] Beneficial Effects: This invention is an improved invention. It proposes a design method for a gas phase temperature measurement probe for high-speed, low-temperature cloud and fog fields. By combining the working conditions of high-speed, low-temperature cloud and fog fields, the gas-liquid separation structure configuration of the backward temperature measurement probe is designed. The structural design of the temperature measurement probe configuration after icing is obtained by combining icing numerical simulation. This solves the coupling problem between icing calculation and two-phase flow field calculation, which improves the gas-liquid separation effect of the temperature measurement probe and reduces the impact of icing on the temperature measurement accuracy. At the same time, different gas phase temperature measurement probes for high-speed, low-temperature cloud and fog fields can be designed for different domestic icing wind tunnel working conditions, making it widely applicable. In conventional icing numerical simulations, droplet trajectories cannot be obtained, thus the gas-liquid separation effect of the temperature probe cannot be determined. Furthermore, the ice shape results from icing calculations cannot be directly used for two-phase flow field calculations. Therefore, the design method of this invention reconstructs the geometric model of the temperature probe after icing through icing numerical simulation, resolving the coupling problem between icing calculations and two-phase flow field calculations. Based on the reconstructed iced temperature probe model, two-phase flow simulation is performed, and combined with the designed suction flow rate, the gas-liquid separation results of the iced temperature probe are obtained. Simultaneously, this invention uses icing numerical simulation to determine the critical thickness of icing on the temperature probe's configuration wall, providing a time reference for the normal use of the temperature probe in icy and foggy environments, and helping to reduce probe failure caused by icing.

[0025] This invention also provides a gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields, designed using the aforementioned design method for a gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields. The probe includes a hollow variable-diameter bend, comprising a small-diameter hollow tube and a large-diameter hollow bend connected to one end thereto. A backward step is provided at the connection between the small-diameter hollow tube and the large-diameter hollow bend. A probe inlet is provided at the end of the small-diameter hollow tube away from the large-diameter hollow bend, forming a gas-liquid separation structure. A temperature sensing element is provided in the large-diameter hollow bend at a position away from the small-diameter hollow tube.

[0026] Beneficial Effects: The vapor phase temperature probe of this invention for high-speed, low-temperature cloud and fog fields is applicable to various operating conditions in domestic icing wind tunnels. It also improves the gas-liquid separation effect of the probe, reducing the impact of wall icing on measurement accuracy. Furthermore, the vapor phase temperature probe of this invention allows for visualization experiments. By using a high-speed camera to photograph the probe's inlet, and observing no droplets following the airflow into the probe's internal flow channel, and conducting temperature measurement experiments, the analysis of the probe's temperature measurement curves under different operating conditions demonstrates that the probe measures the vapor phase temperature, indicating good gas-liquid separation. Accurate vapor phase temperature measurement is achieved within the target operating range.

[0027] The present invention also provides an application of a gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields, a gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields designed based on the above-mentioned design method, and the application of the above-mentioned gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields in gas phase temperature measurement in high-speed low-temperature cloud and fog fields.

[0028] Beneficial effects: The gas phase temperature probe for high-speed low-temperature cloud and fog fields provided by this invention has a wide range of applications and good gas-liquid separation effect in the gas phase temperature measurement of high-speed low-temperature cloud and fog fields.

[0029] Furthermore, the application also includes: establishing a temperature correction model for the temperature measuring probe, used to correct the gas phase temperature in the high-speed low-temperature cloud and fog field measured by the gas phase temperature measuring probe used for the high-speed low-temperature cloud and fog field.

[0030] In S1, the design of the gas-liquid separation structure of the temperature measuring probe based on the backward temperature measuring probe configuration, combined with the backward step two-phase flow theory and the working conditions of high-speed low-temperature cloud fog field, specifically includes: based on the backward temperature measuring probe configuration, combined with the motion state of droplets in the airflow in the backward step two-phase flow of the backward temperature measuring probe configuration, and based on the droplet size and velocity, calculating the maximum backward step height in the gas-liquid separation structure of the temperature measuring probe, and then designing the gas-liquid separation structure of the temperature measuring probe; by determining the maximum backward step height, droplets are effectively prevented from entering the temperature measuring area, ensuring the effectiveness of gas-liquid separation.

[0031] In step S4, the icing numerical simulation includes: calculating the airflow field based on the initial grid and combining it with droplet impact calculations to obtain the icing calculation of the temperature probe wall, thus reconstructing the boundary of the icing model and obtaining the reconstructed geometric model of the iced temperature probe configuration; simultaneously, determining whether the icing time during the icing numerical simulation reaches the set usage time of the temperature probe configuration; if it does, the simulation ends; otherwise, the above icing numerical simulation steps are repeated until the icing time during the icing numerical simulation reaches the set usage time of the temperature probe configuration. Through the above high-precision geometric reconstruction method, the geometric model of the iced temperature probe is reconstructed, solving the coupling problem between icing calculation and two-phase flow field calculation.

[0032] In S4, the two-phase flow simulation based on the reconstructed geometric model of the icing-out temperature probe configuration, combined with the suction flow rate of the designed temperature probe configuration, is used to simulate the near-wall flow field changes caused by the icing-out temperature probe configuration in the two-phase flow field. Specifically, in the two-phase flow simulation, based on the suction flow rate of the designed temperature probe configuration, and considering the shear layer and separation vortex of the droplets flowing in the near-wall flow field of the icing-out temperature probe configuration in the two-phase flow, the LES-WALE turbulence model is used to simulate and calculate the near-wall flow field of the icing-out temperature probe configuration, which improves the calculation accuracy and efficiency, and thus obtains more accurate flow field calculation results.

[0033] The LES-WALE turbulence model includes the large eddy model and the WALE model. The large eddy model is used to model and calculate the large eddies in the separated eddies while simultaneously modeling the small eddies within them. It considers both large and small eddy structures, improving calculation accuracy by modeling the small eddies while simultaneously modeling the large eddies. The WALE model is used to optimize the simulation calculation of the near-wall flow field of the icing temperature probe configuration and to correct the turbulent viscosity of the shear layer, resulting in more accurate calculations in laminar and shear flow regions.

[0034] In S5, the simulation results of the near-wall flow field changes and gas-liquid flow characteristics caused by the icing-out temperature probe configuration in the two-phase flow field also include: acquiring and analyzing the flow field diagram of the icing-out temperature probe configuration; if there is no disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration, then continue to analyze the relevant data of droplets in the gas and liquid entering the icing-out temperature probe configuration to determine whether droplets are detected at the temperature sensing element detection position in the icing-out temperature probe configuration; if there is a disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration, then repeat steps S1-S4 until there is no disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration. This can preliminarily determine the separation effect of the temperature probe configuration and enhance the convenience and accuracy of the separation effect judgment.

[0035] The design method for the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields further includes: after S6, performing strength verification on the designed temperature measurement probe configuration. The strength verification of the designed temperature measurement probe configuration specifically includes: simulating the time-averaged flow field of the temperature measurement probe configuration at 160 m / s, extracting the pressure distribution results on the wall of the temperature measurement probe configuration, performing transient stress calculation and equivalent stress calculation based on the pressure distribution results on the wall of the temperature measurement probe configuration, evaluating the stress results of the temperature measurement probe, and then determining whether the structural strength of the temperature measurement probe meets the requirements, thus ensuring the practicality of manufacturing the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields.

[0036] The application also includes: establishing a temperature correction model for the temperature probe, which is used to correct the gas phase temperature in the high-speed low-temperature cloud field measured by the gas phase temperature probe used in the high-speed low-temperature cloud field. The temperature correction model considers factors such as turbulence, suction and wall heat transfer, which improves the temperature measurement accuracy. After the temperature is corrected by the temperature correction model, the temperature measurement error of the temperature probe is controlled within 0.5℃, which meets the measurement accuracy requirements. At the same time, the effectiveness of the temperature correction model is verified. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the temperature measurement principle of the temperature measuring probe configuration in the design method of the gas phase temperature measuring probe for high-speed low-temperature cloud and fog fields of the present invention.

[0038] Figure 2 This is a schematic diagram of the temperature probe configuration in the design method of the gas phase temperature probe for high-speed low-temperature cloud and fog fields of the present invention.

[0039] Figure 3 This is a schematic diagram of the structure of the temperature probe configuration separation effect monitoring point in the design method of the gas phase temperature probe for high-speed low-temperature cloud and fog fields of the present invention.

[0040] Figure 4 This is a schematic diagram of the motion state of droplets entrained in the airflow in the temperature measuring probe configuration in the design method of the gas phase temperature measuring probe for high-speed low-temperature cloud and fog fields of the present invention.

[0041] Figure 5 These are schematic diagrams of four different temperature probe configurations in the design method of the gas phase temperature probe for high-speed low-temperature cloud and fog fields of the present invention.

[0042] Figure 6 These are the statistical results of liquid inlet volume for four different temperature probe configurations in the design method of the gas phase temperature probe for high-speed low-temperature cloud and fog fields of the present invention.

[0043] Figure 7 This is a comparison of droplet distribution results for four different temperature probe configurations in the design method of the gas phase temperature probe for high-speed low-temperature cloud and fog fields of the present invention.

[0044] Figure 8 This is a planar droplet distribution diagram along the v-axis in the design method of the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields of the present invention.

[0045] Figure 9 The result of the stress calculation of the temperature probe configuration in the design method of the gas phase temperature probe for high-speed low-temperature cloud and fog fields of the present invention;

[0046] Figure 10This is a schematic diagram of the placement of a high-speed camera during the verification process of the vapor phase temperature measurement probe for high-speed low-temperature cloud and fog fields of the present invention.

[0047] Figure 11 This is a schematic diagram of the imaging area of ​​the vapor phase thermometry probe for high-speed low-temperature cloud and fog fields of the present invention during the verification process.

[0048] Figure 12 This is a schematic diagram of the installation of a pipe endoscope during the verification process of the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields of the present invention.

[0049] In the diagram, 1. Two-phase flow, 2. Pure airflow, 3. Temperature sensing element, 4. Suction pipe, 5. Vacuum pump, 6. Small-diameter hollow tube, 7. Large-diameter hollow bend, 8. Backward step, 9. Separation vortex, 10. Shear layer, 11. Time-averaged boundary, 12. Reattachment layer, 13. Air duct outlet, 14. Light source, 15. High-speed camera, 16. Low-temperature gas-liquid two-phase flow, 17. Control group probe, 18. Experimental stage flow channel outlet, 19. Monitoring area, 20. Suction channel, 21. Endoscope. Detailed Implementation

[0050] As cited in the background section, the prior art has poor gas-liquid separation performance and limited applicable operating conditions for backward temperature probes. Therefore, this invention provides a design method for a gas phase temperature measurement probe for high-speed, low-temperature cloud and fog fields, comprising the following steps: First, based on the backward temperature measurement probe configuration, combined with the backward step two-phase flow theory in the backward temperature measurement probe configuration and the working conditions of the high-speed, low-temperature cloud and fog field, a gas-liquid separation structure configuration of the backward temperature measurement probe is designed, thereby obtaining the temperature measurement probe configuration. The temperature measurement probe configuration includes a temperature sensing element detection position to obtain different temperature measurement probe configurations under different high-speed, low-temperature cloud and fog field working conditions. Second, based on the temperature measurement probe configuration, two-phase flow simulation and suction flow simulation are performed to simulate the gas-liquid flow characteristics caused by the suction flow of the temperature measurement probe configuration in the two-phase flow field, and the suction flow of the temperature measurement probe configuration is designed for subsequent two-phase flow simulation. Then, icing numerical simulation is performed on the temperature measurement probe configuration to obtain a reconstructed geometric model of the icing temperature measurement probe configuration. Based on the reconstructed geometric model of the icing temperature measurement probe configuration, two-phase flow simulation is performed, combined with the designed suction flow of the temperature measurement probe configuration, to achieve the simulation of the gas-liquid flow characteristics under different high-speed, low-temperature cloud and fog field working conditions. Simulations of the near-wall flow field changes and gas-liquid flow characteristics caused by the icing probe configuration in a two-phase flow field are used to address the coupling problem between icing calculations and two-phase flow field calculations. Finally, the simulation results of the near-wall flow field changes and gas-liquid flow characteristics caused by the icing probe configuration in a two-phase flow field are analyzed to obtain relevant data on droplets in the gas and liquid within the icing probe configuration, which is used to assess the gas-liquid separation effect. If no droplets are detected at the temperature sensing element detection position in the icing probe configuration, the design is complete; otherwise, the first five steps are repeated until no droplets are detected at the temperature sensing element detection position in the icing probe configuration. This ensures that the designed probe improves the gas-liquid separation effect and reduces the impact of icing on the probe wall on temperature measurement accuracy. Simultaneously, different gas-phase temperature probes for high-speed, low-temperature cloud and fog fields are designed for different domestic icing wind tunnel operating conditions, making them widely applicable.

[0051] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0052] The following description, with reference to the accompanying drawings, describes a vapor phase thermometry probe for high-speed, low-temperature cloud and fog fields, its design method, and its application.

[0053] The following combination Figure 1 This application provides a detailed description of the design method for a gas phase temperature measurement probe for high-speed, low-temperature cloud and fog fields.

[0054] like Figure 1 and Figure 2 As shown, the design method for a gas phase temperature measurement probe used in high-speed low-temperature cloud and fog fields includes the following steps: First, based on the backward temperature measurement probe configuration, combined with the backward step two-phase flow theory in the backward temperature measurement probe configuration and the working conditions of the high-speed low-temperature cloud and fog field, the gas-liquid separation structure configuration of the backward temperature measurement probe is designed, thereby obtaining the temperature measurement probe configuration, and a temperature sensing element is set in the temperature measurement probe configuration; Second, based on the temperature measurement probe configuration, two-phase flow simulation and suction flow simulation are performed to realize the simulation of the gas-liquid flow characteristics caused by the suction flow of the temperature measurement probe configuration in the two-phase flow field, and the simulation results are analyzed to obtain relevant data of droplets in the gas and liquid entering the temperature measurement probe configuration; Then, the relevant data of droplets in the gas and liquid entering the temperature measurement probe configuration are analyzed. If no droplets are detected at the detection position of the temperature sensing element in the temperature measurement probe configuration, the suction flow design of the temperature measurement probe configuration is completed, and the next step is entered; otherwise, the suction flow simulation in the previous step is repeated until the temperature sensing element in the temperature measurement probe configuration is detected. No droplets were detected at the temperature sensing element detection position. Next, icing numerical simulations were performed on the temperature probe configuration to obtain a reconstructed geometric model of the iced temperature probe configuration. Based on this reconstructed geometric model, two-phase flow simulations were conducted. Combined with the suction flow rate of the designed temperature probe configuration, simulations of the near-wall flow field changes and gas-liquid flow characteristics caused by the iced temperature probe configuration in the two-phase flow field were achieved. Finally, the simulation results of the near-wall flow field changes and gas-liquid flow characteristics caused by the iced temperature probe configuration in the two-phase flow field were analyzed to obtain relevant data on droplets in the gas and liquid entering the iced temperature probe configuration. If no droplets were detected at the temperature sensing element detection position in the iced temperature probe configuration, the design was considered complete; otherwise, the previous five steps were repeated until no droplets were detected at the temperature sensing element detection position in the iced temperature probe configuration. Specifically, as shown... Figure 3 As shown, in the simulated temperature probe configuration, four monitoring points, Plane1, Plane2, Plane3 and Plane4, are designed. Among them, Plane4 is the detection position of the temperature sensing element set in the temperature probe configuration. If no droplet is detected passing through Plane4, the design is complete.

[0055] In one specific embodiment of this application, based on the backward temperature probe configuration, combined with the backward step two-phase flow theory and the working conditions of high-speed low-temperature cloud fog field, the design of the gas-liquid separation structure configuration of the temperature probe specifically includes: based on the backward temperature probe configuration, combined with the motion state of droplets in the airflow in the backward step two-phase flow in the backward temperature probe configuration, and based on the droplet size and velocity, calculating the maximum backward step height in the gas-liquid separation structure configuration of the temperature probe, and then designing the gas-liquid separation structure configuration of the temperature probe.

[0056] Specifically, the temperature measurement principle of the backward temperature probe is as follows: Figure 1 and Figure 2 As shown, the backward temperature probe includes a hollow variable-diameter bend, which comprises a small-diameter hollow tube 6 and a large-diameter hollow bend 7 connected to one end of the small-diameter hollow tube 6 and the large-diameter hollow bend 7. A backward step 8 is provided at the connection between the small-diameter hollow tube 6 and the large-diameter hollow bend 7. A probe air inlet is provided at the end of the small-diameter hollow tube 6 away from the large-diameter hollow bend 7. A temperature sensing element 3 is provided in the large-diameter hollow bend 7 at a position away from the small-diameter hollow tube 6. The probe air inlet is placed facing the leeward side. After the two-phase flow 1 is turbulent by the temperature probe, a pure airflow 2 is separated and approaches the air inlet. Under the action of the vacuum pump 5, the airflow is drawn into the temperature probe through the suction pipe 4, and the airflow enters the flow channel, passes through the temperature sensing element 3, and completes the temperature measurement.

[0057] In another embodiment of this application, the gas-liquid separation effect of the temperature probe configuration can be determined based on the amount of liquid entering the temperature probe configuration, such as... Figure 3 As shown, the liquid inlet of the temperature probe is counted, that is, the liquid inlet at the Plane1 monitoring point. The less liquid inlet, the better the gas-liquid separation effect of the temperature probe configuration.

[0058] In another embodiment of this application, the amount of liquid entering through the backward step 8 in the temperature probe configuration, i.e. the amount of liquid entering at the Plane2 monitoring point, is counted. The less liquid entering, the better the gas-liquid separation effect of the temperature probe configuration.

[0059] In another embodiment of this application, the amount of liquid entering through the bend in the large-diameter hollow bend 7 of the temperature probe configuration, i.e. the amount of liquid entering at the Plane 3 monitoring point, is counted. The less liquid entering, the better the gas-liquid separation effect of the temperature probe configuration.

[0060] The main structural parameters of the temperature probe configuration are as follows: Figure 2As shown, the large-diameter hollow bend 7 of the temperature probe configuration includes a main pipe with a diameter of D, a horizontal section length of L, an outer diameter of the temperature probe inlet of d, a length of the small-diameter hollow tube 6 of l, and a radius difference of h between the main pipe and the small-diameter hollow tube 6, which is the height of the backward step 8. The initial determination of the main pipe diameter D as 19 mm is made; the remaining dimensions will be designed further. The operating conditions for domestic icing wind tunnels are: air velocity 50-160 m / s, and liquid water content (LWC) not exceeding 3 g / m³. 3 The droplet size is 15-50 μm, and the minimum inflow gas velocity is 50 m / s.

[0061] The calculation process for the maximum step height is as follows:

[0062] like Figure 4 As shown, in the backward flow of step 8, the droplets entrained in the airflow exhibit two motion states: one is following the shear layer 10 and the separation vortex 9 under the influence of the airflow; the other is maintaining their original trajectory. The motion state of the droplets depends on the magnitude of the droplet Stokes number (St), which characterizes the ratio of droplet inertia to diffusion. The smaller the value, the smaller the droplet inertia, the easier it is to follow the fluid motion, and the more obvious its diffusion effect; conversely, the larger the Stokes number, the greater the droplet inertia, and the less obvious the droplet's following motion. The calculation of the droplet Stokes number is shown in Equation 1:

[0063] Formula 1;

[0064] in, , And St>1, τ p With τ f The characteristic times for droplets and gas flow are ρ and ρ, respectively. p Let d be the droplet density. p Where μ is the droplet diameter. f Let be the fluid dynamic viscosity, h be the step height, and U be the airflow velocity.

[0065] Therefore, using the droplet size of 15 μm and the velocity of 50 m / s in the wind tunnel conditions measured above as the design conditions, the maximum height of the backward step 8 was calculated to be 7.5 mm, meaning that the height h of the backward step 8 of the temperature measuring probe must not exceed 7.5 mm. After initially determining the height h of the backward step 8, simulations were conducted on temperature measuring probes with different structural dimensions, different small-diameter hollow tube structures 6, different horizontal pipe section lengths, and different suction flow rates to obtain the temperature measuring probe configuration with the theoretically best gas-liquid separation effect.

[0066] Specifically, such as Figure 4As shown, for different small-diameter hollow tubes 6, the height and length of the backward step 8 affect the generated separation vortex 9 and reattachment layer 12 during particle flow in the backward step 8, thus affecting the particle trajectory. Therefore, by adjusting the diameter and length of the small-diameter hollow tube 6, four different temperature probe configurations were obtained for the above operating conditions. The influence of the structural dimensions of the small-diameter hollow tube 6 on the gas-liquid separation effect was studied. The specific structural parameters are as follows: Figure 5 As shown in Table 1, the four temperature probe configurations were simulated under the same typical operating conditions. The specific operating parameters were: initial gas velocity (droplet velocity) 80 m / s, LWC = 3 g / m³. 3 The initial air temperature was 268 K, the droplet temperature was 273 K, the droplet size was 1-50 μm, and the suction flow rate was 3 slpm (standard liters per minute). From the flow field and droplet distribution, it can be seen that during the backward step flow, most high-speed droplets move forward under inertia, while a small number of lower-velocity and extremely small droplets follow the airflow through shear separation. Some droplets are captured by the separation vortex structure 9 and swirl at the bottom of the step; others follow the separation layer, flowing close to the wall to the vicinity of the channel inlet, and some of these droplets enter the channel of the temperature probe configuration under suction. The number of droplets entering the channel characterizes the gas-liquid separation effect of each configuration. The droplet data passing through the inlet plane of the temperature probe configuration within 0.009 s are statistically analyzed, and the statistical results of the liquid inflow for each configuration are shown in Figure 6.

[0067] Table 1. Specific structural parameters of four different temperature probe configurations

[0068]

[0069] The results showed that all four structures exhibited some liquid ingress, but no droplets were detected passing through the area where the temperature sensing element was located. This indicates that even if droplets entered the flow channel of the temperature probe with the airflow, they would collide with and adhere to the wall before passing through the bend section, making it difficult for them to reach the area where the temperature sensing element is located. Therefore, all four structural designs are acceptable. To select the optimal structural design, according to statistical results, the Type 1 configuration has the smallest liquid ingress volume, and the droplet diameter entering the flow channel is less than 1 μm. Under actual operating conditions, the number of droplets with a diameter less than 1 μm is extremely small, and their liquid mass is very small, so their impact on gas phase temperature measurement is negligible. Therefore, it is considered that among the four configurations, the Type 1 configuration has the smallest droplet mass entering the flow channel, and the gas-liquid separation effect is the best under icing wind tunnel conditions. Therefore, the small-diameter hollow tube 6 structure in the temperature probe configuration design should be selected from the Type 1 configuration.

[0070] For designs with different horizontal pipe section lengths, vortices are generated behind the vertical pipe section of the temperature sensing probe after the airflow passes through it. If the distance between the temperature sensing probe inlet and the vertical pipe section is too close, it may interfere with the backward stepped flow region at the temperature sensing probe inlet. Based on the Type 1 temperature sensing probe configuration, the length of the horizontal pipe section of the temperature sensing probe is changed to alter the influence of the vortex on the flow field of the small-diameter hollow tube 6. An excessively short horizontal pipe section will disrupt the backward stepped flow region of the narrowed section of the temperature sensing probe, affecting the gas-liquid separation effect. Figure 7 As shown, when the outer diameter of the main pipe is 19 mm, the horizontal section length of the temperature probe needs to be at least 100 mm to avoid the adverse effects of turbulence in the vertical pipe section on gas-liquid separation. However, the horizontal section length of the temperature probe should not be too long to avoid excessive contact time between the airflow and the wall, which could lead to temperature changes in the airflow and affect the measurement accuracy.

[0071] In one specific embodiment of this application, two-phase flow simulation and suction flow simulation are performed based on the temperature probe configuration to simulate the gas-liquid flow characteristics caused by the suction flow of the temperature probe configuration in the two-phase flow field. The simulation results are analyzed to obtain relevant data of droplets in the gas and liquid entering the temperature probe configuration. If no droplets are detected at the detection position of the temperature sensing element in the temperature probe configuration, the suction flow design of the temperature probe configuration is completed, and the next step is initiated. Otherwise, the suction flow simulation in the previous step is repeated until no droplets are detected at the detection position of the temperature sensing element in the temperature probe configuration.

[0072] Specifically, without considering droplet adhesion flow, the suction of the temperature probe is the primary factor causing droplets to enter the flow channel. As the suction flow rate increases, more droplets are attracted, altering their trajectories and increasing the probability of droplets entering the temperature probe's inlet. Under these conditions, as the suction flow rate increases, the airflow velocity within the flow channel of the temperature probe configuration increases significantly, and the influence range of suction on the external flow field of the temperature probe configuration also increases significantly. Simultaneously, the increased air velocity within the flow channel of the temperature probe configuration leads to more complete heat exchange between the airflow and the sensing element, resulting in higher heat exchange efficiency and shortening the time required for the temperature probe configuration to establish temperature equilibrium. However, with the increase in suction flow rate, more droplets are attracted, altering their trajectories and increasing the probability of droplets entering the temperature probe configuration's inlet, leading to a significant increase in the liquid inlet volume. Therefore, during the simulation of the suction flow design for the temperature probe configuration, the success of the design is determined by whether droplets are detected at the sensing element's detection position within the temperature probe configuration at a given suction flow rate. It can be concluded that the suction flow rate of the temperature probe configuration obtained under the above conditions should not exceed 90 slpm to avoid drawing excessive droplets into the flow channel.

[0073] Meanwhile, since the operating parameters such as gas flow rate, liquid water content, and droplet size all affect the final gas-liquid separation effect during gas-liquid separation by the temperature probe, multiple different operating conditions are set based on the above parameters, and various temperature probe configurations with different structures are designed. At the same time, icing numerical simulation and two-phase flow simulation are carried out to obtain different temperature probe configurations that are suitable for different operating conditions. The design method of this application can design different gas phase temperature probes for high-speed low-temperature cloud and fog fields for different domestic icing wind tunnel operating conditions, making it widely applicable.

[0074] In one specific embodiment of this application, the icing numerical simulation includes: calculating the airflow field based on an initial grid, and combining this with droplet impact calculations to obtain the icing calculation of the temperature probe wall, thereby reconstructing the boundary of the icing model and obtaining the reconstructed geometric model of the iced temperature probe configuration; simultaneously, determining whether the icing time during the icing numerical simulation process reaches the set usage time of the temperature probe configuration; if it does, the simulation ends; otherwise, the above icing numerical simulation steps are repeated until the icing time during the icing numerical simulation process reaches the set usage time of the temperature probe configuration. Specifically, the icing numerical simulation method for the temperature probe wall is as follows: first, the airflow field is calculated based on the initial grid, then droplets are added for calculation to obtain the droplet impact distribution results, and icing calculations are performed based on this to obtain the final ice shape; and the icing time during the icing numerical simulation process is checked to determine whether it reaches the set usage time of the temperature probe configuration; otherwise, the above steps are repeated until the calculation is completed. Icing calculations are performed using Fensap-ice software, which can be coupled with Fluent for calculations. Therefore, during icing numerical simulation, the airflow field is first calculated in Fluent, then imported into Fensap-ice to calculate the droplets, and finally icing calculations are performed to achieve icing simulation.

[0075] In the simulation of water droplet impact characteristics, the Eulerian method treats droplets in the airflow as a continuous phase, focusing on controlling the changes in droplets within the volume. This method is more advantageous and efficient when solving complex three-dimensional surface configurations; therefore, the Eulerian method is used as the droplet solution algorithm. In the high-speed, low-temperature cloud field generated by an icing wind tunnel, the total volume fraction of supercooled droplets and ice crystals generally does not exceed 10%. Therefore, a discrete phase model (DPM) is used to calculate supercooled droplets. The continuous phase, i.e., droplets in the airflow, is calculated using the Eulerian method, while the discrete phase, i.e., supercooled droplets, is calculated using the Lagrangian method. A two-way coupled calculation is performed, comprehensively considering gas-liquid phase interactions, droplet motion, and heat and mass transfer processes.

[0076] In one specific embodiment of this application, such as Figure 4As shown, a two-phase flow simulation is performed based on the reconstructed geometric model of the icing-out temperature probe configuration. Combined with the suction flow rate of the designed temperature probe configuration, the simulation of the near-wall flow field changes caused by the icing-out temperature probe configuration in the two-phase flow field is achieved. This includes: In the two-phase flow simulation, based on the suction flow rate of the designed temperature probe configuration, and considering the shear layer 10 and separation vortex 9 flowing through the droplets in the near-wall flow field of the icing-out temperature probe configuration, the LES-WALE turbulence model is used to simulate and calculate the near-wall flow field of the icing-out temperature probe configuration. The LES-WALE turbulence model includes the large eddy model and the WALE model. The large eddy model is used to model and calculate the large eddies in the separation vortex 9 while simultaneously modeling the small eddies within the separation vortex 9; the WALE model is used to optimize the simulation calculation of the near-wall flow field of the icing-out temperature probe configuration and to correct the turbulent viscosity of the shear layer 10.

[0077] Specifically, simulations were performed on the near-wall flow field of the icing temperature probe configuration. The flow regions of the droplet in the near-wall flow field of the icing temperature probe configuration include a shear layer 10, a separation vortex 9, a time-averaged boundary 11, and a reattachment layer 12. In the LES (Large Eddy Model), only the large eddies are modeled. Since small eddies tend to be isotropic, it is easier to find a universal turbulence model and directly model them; therefore, the large eddy model was chosen to calculate the near-wall flow field of the temperature probe configuration. Simultaneously, the WALE model was used to optimize the calculation of the near-wall flow field of the temperature probe configuration, and the turbulent viscosity in the shear layer region was corrected. Therefore, the WALE model makes the calculation of the flow region in the shear layer 10 more accurate. LES models small-sized eddies, which reduces the number of meshes required for calculation and lowers the time step requirement, while maintaining accuracy. The LES large eddy model considers both large and small eddy structures simultaneously. While modeling and calculating the large eddy, it also models the small eddy, resulting in higher calculation accuracy and more accurate flow field calculation results. Therefore, this invention selects the LES-WALE model as the turbulence model to simulate the near-wall flow field of the icing temperature probe configuration.

[0078] In another embodiment of this application, the simulation results of the near-wall flow field changes and gas-liquid flow characteristics caused by the icing-out temperature probe configuration in the two-phase flow field are further analyzed by: acquiring and analyzing the flow field diagram of the icing-out temperature probe configuration; if there is no disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration, then the relevant data of droplets in the gas and liquid entering the icing-out temperature probe configuration are analyzed to determine whether droplets are detected at the temperature sensing element detection position in the icing-out temperature probe configuration; if there is a disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration, then the above steps are repeated until there is no disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration.

[0079] Specifically, such as Figure 8 As shown, when the temperature probe is not iced, its droplet distribution boundary is relatively stable, exhibiting two smooth curves. However, once ice accumulates on the probe wall, a significant bulge forms along the z-axis within 60 seconds, disturbing the airflow and causing fluctuations in the droplet distribution boundary. The higher the bulge, the more severe the disturbance, the less stable the droplet distribution boundary, and the larger the fluctuation amplitude, resulting in a more severe negative impact on gas-liquid separation. In summary, excessive ice buildup on the temperature probe wall disturbs the near-wall airflow, causing fluctuations and diffusion in the droplet distribution boundary, ultimately negatively affecting gas-liquid separation. Therefore, the separation effect can be predicted in advance by observing the presence or absence of a disturbed droplet distribution boundary in the simulated flow field diagram of the near-wall flow field changes caused by the iced temperature probe configuration in the two-phase flow field.

[0080] In another embodiment of this application, the design method for a gas phase temperature probe for a high-speed, low-temperature cloud field further includes: performing a strength check on the designed temperature probe configuration. Specifically, the strength check on the designed temperature probe configuration includes: simulating the time-averaged flow field of the temperature probe configuration at 160 m / s, extracting the pressure distribution results on the wall of the temperature probe configuration, performing transient stress calculation and equivalent stress calculation based on the pressure distribution results on the wall of the temperature probe configuration, evaluating the stress results of the obtained temperature probe, and then determining whether the structural strength of the temperature probe meets the requirements.

[0081] Specifically, the high-speed inflow in the icing wind tunnel is relatively stable, with virtually no fluctuations in velocity or pressure. Therefore, the time-averaged flow field of the temperature probe at its maximum air velocity (160 m / s) was simulated, and the pressure distribution on the probe wall was extracted. Transient stress calculations were performed, and equivalent stress calculations were conducted based on the fourth strength theory to assess the stress on the temperature probe. The calculation results are as follows: Figure 9 As shown, the temperature probe is subjected to a clockwise bending moment under the impact of the airflow. The stress on the probe wall is approximately 13.162 MPa, while the minimum yield strength of 304 stainless steel is approximately 185 MPa, which is much greater than the maximum stress experienced by the probe. Simultaneously, the ductile-brittle transition temperature of 304 stainless steel is approximately -190℃, far lower than the experimental environment. Therefore, it can be concluded that the structural strength of the temperature probe made of 304 stainless steel meets the requirements.

[0082] The present invention also provides a gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields, which is designed using the above-mentioned design method for a gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields. The gas phase temperature measurement probe includes a hollow variable diameter bend tube, which includes a small diameter hollow tube 6 and a large diameter hollow bend tube 7 connected to one end thereto. A backward step 8 is provided at the connection between the small diameter hollow tube 6 and the large diameter hollow bend tube 7. A probe air inlet is provided at the end of the small diameter hollow tube 6 away from the large diameter hollow bend tube 7. A temperature sensing element 3 is provided in the large diameter hollow bend tube 7 at a position away from the small diameter hollow tube 6.

[0083] Specifically, based on the constructed high-speed, low-temperature gas-liquid two-phase flow experimental platform, simulating the actual icing duct working environment, the aforementioned temperature probe test piece was placed in a high-speed, low-temperature two-phase inflow to conduct experiments and verify the actual performance of the temperature probe. The lower the droplet velocity, the easier it is to change its trajectory, and the greater the probability of it entering the flow channel. Therefore, the lowest inflow velocity (50 m / s) and an LWC of 3 g / m were selected. 3 The footage was taken under the condition that the suction flow rate was 10.1687 slpm.

[0084] like Figure 10 As shown, the high-speed cryogenic gas-liquid two-phase flow experimental platform mainly consists of three systems. First, there is the high-speed cryogenic airflow supply system, which uses a centrifugal fan as the air source to provide sufficient air. Due to the chaotic airflow generated by the centrifugal fan, which has extremely high turbulence, a rectifier section is added to the air duct to improve the uniformity of the incoming flow. The rectifier section adopts the form of a rectifier grid plus a honeycomb structure. The airflow then passes through the rectifier section for rectification and then mixes and exchanges heat with the liquid nitrogen spray generated by the liquid nitrogen spray system to form a cryogenic airflow. The droplet generation system is placed after the high-speed cryogenic airflow supply system. It generates a large number of droplets through a gas-liquid assisted atomizing nozzle, which mixes with the cryogenic airflow to form a cryogenic gas-liquid two-phase flow. The probe testing system is located at the air duct outlet 13 and consists of a temperature probe and supporting equipment. Among these, an efficient heat exchange system and an airflow acceleration device are designed for the experimental platform to simulate the high-speed cryogenic cloud and fog environment in an icing wind tunnel. To ensure sufficient heat exchange time, the initial airflow velocity should not be too low. However, the experimental conditions require high wind speeds. Therefore, a constricted design was implemented for the air duct, with a maximum cross-sectional dimension of 600×600 mm and an outlet cross-sectional dimension of 100×100 mm. The constriction section of the air duct was designed with reference to the aforementioned icing wind tunnel, with the constriction angle set at 7°, thus determining the structural dimensions of the constriction section.

[0085] Compared to heat pipe cooling, liquid nitrogen spray cooling offers significantly higher cooling efficiency. Liquid nitrogen evaporates extremely quickly and possesses a high latent heat of 199.176 KJ / kg under standard operating conditions. The degree of cooling can be controlled simply by adjusting the liquid nitrogen spray flow rate. Liquid nitrogen nozzles are installed within the duct, with three nozzles placed side-by-side to ensure uniform distribution. A 4000 mm long duct is installed after the liquid nitrogen spray system to allow sufficient time for evaporation and heat exchange. Atomizing nozzles are then installed to generate droplets, which mix with the cryogenic gas flow, ultimately forming a cryogenic gas-liquid two-phase flow.

[0086] like Figure 10 and Figure 12 As shown, the temperature probe is mounted on the test platform, which consists of a frame and a probe mounting bracket. The main body of the probe mounting bracket is a two-axis moving platform, on which the temperature probe is mounted. A control probe 17 is mounted above the bracket as a control experiment object for the temperature probe. A high-speed camera 15 and a light source 14 are positioned on either side of the low-temperature gas-liquid two-phase flow 16. The frame is a double-layer platform; the lower layer houses the flow meter, power supply, vacuum pump, and other equipment for the temperature probe. To prevent droplets in the two-phase flow from contacting the lower layer's electronic components and damaging the instrument, a baffle plate is added to the windward side of the frame. The flow channel outlet 18 of the experimental platform is located on the back of the temperature probe. A temperature sensing element is used to monitor the temperature at the monitoring area 19. An endoscope 21 is installed in the large-diameter hollow bend 7 of the temperature probe at the end furthest from the small-diameter hollow tube 6; a suction channel 20 is also located at this position.

[0087] In selecting the temperature sensing element, thermocouples are the primary choice. Furthermore, the thermocouple with the corresponding measurement range is selected based on the temperature range of the wind tunnel being used. For the aforementioned gas phase temperature probe used in high-speed, low-temperature cloud and fog fields, a platinum resistance thermometer (PT1000) is chosen as the sensing element. Platinum resistance thermometers are vibration-resistant, stable, and highly accurate, and are suitable for low-temperature environments. The PT1000 has a temperature measurement range of -50℃ to 500℃ and a measurement accuracy of ±0.15 +0.002|T|. Platinum resistance thermometers are mainly available in two packaging structures: insulated and exposed. The temperature change rate of the temperature probe using both types of platinum resistance thermometers was tested. The response rate of the exposed type is approximately four times that of the insulated type; therefore, the exposed type platinum resistance thermometer is used as the sensing element for the temperature probe.

[0088] The specific steps for using a temperature probe to conduct simulated icing wind tunnel environment testing are as follows:

[0089] (1) Install the temperature probe, ensure that the temperature probe is placed horizontally, connect the pipeline and the matching instruments, connect each sensor to the NI data acquisition unit, and connect the NI data acquisition unit to the computer to test whether the data acquisition system is operating normally.

[0090] (2) Turn on vacuum pump 5 and adjust the vacuum pump flow rate. Observe the display screen of the thermal gas mass flow meter and wait for the reading to stabilize at the target value.

[0091] (3) Turn on the fan, adjust the fan speed through the frequency converter, and use a Pitot tube to measure the airflow velocity at the air duct outlet 13 to ensure that the airflow velocity reaches the target operating conditions.

[0092] (4) After the airflow stabilizes, turn on the computer and start data acquisition.

[0093] (5) Observe the pressure reading of the liquid nitrogen tank and adjust the pressure of the liquid nitrogen tank to the target value through the pressure regulating valve. Then open the liquid nitrogen tank outlet valve to generate liquid nitrogen spray and create a low-temperature gas-liquid two-phase flow environment.

[0094] (6) Observe the computer data acquisition panel, wait for the temperature probe to re-establish temperature balance in the low temperature airflow, and adjust the gas path pressure and liquid path pressure of the gas-liquid auxiliary atomizing nozzle in advance.

[0095] (7) Open the gas-liquid auxiliary atomizing nozzle to form a high-speed low-temperature gas-liquid two-phase flow 16, and take pictures through the high-speed camera 15; observe the computer data acquisition panel, and stop data acquisition when the temperature probe establishes temperature balance again, turn off the vacuum pump 5, fan, liquid nitrogen spray and gas-liquid auxiliary atomizing nozzle, and end this round of testing.

[0096] Specifically, due to the image frame limitation of the long-distance microscope lens of the high-speed camera 15, it is impossible to include the entire temperature probe head structure in a single frame. Therefore, the temperature probe head is divided into three areas for separate imaging to capture the droplet's trajectory. Before the actual imaging, the camera needs to be calibrated. Calibration can be performed directly using the temperature probe within the image. Since the dimensions of each structure of the temperature probe are known, the actual image frame size can be directly calculated. The temperature probe is manufactured through machining, with a maximum machining error of 0.018mm. Therefore, the measurement error of the captured image is within 0.3%.

[0097] like Figure 11As shown, if few droplets are captured passing through the focal plane in areas one and two of the temperature probe, it indicates that the droplet distribution in this area is sparse and the droplet size is very small (below 15μm), making it difficult for the lens to capture such extremely small droplets. A small number of droplets at the focal plane are captured, all moving in a straight line in the horizontal direction. No droplets with significantly disturbed trajectories are observed, indicating that in the areas on both sides of the temperature probe, droplet movement is largely unaffected by wall turbulence and suction, resulting in good gas-liquid separation. Area three is the temperature probe inlet, where it can be observed whether any droplets ultimately enter the internal flow channel of the temperature probe. At the temperature probe inlet, if there are virtually no droplets on the focal plane, and only occasional droplets moving in a straight line pass near the inlet, it indicates that droplets in the two-phase flow generally do not follow the airflow to the vicinity of the temperature probe inlet, confirming that the temperature probe's turbulence structure can achieve efficient gas-liquid separation of the two-phase flow.

[0098] Based on the analysis of the simulated icing wind tunnel environment test results using the aforementioned temperature measuring probe, in Region 1 above the probe, droplet movement is largely unaffected by wall turbulence and suction, resulting in good gas-liquid separation. In Region 2, the wall-attached droplets are larger and, influenced by the airflow, deform and break at the narrowing section of the probe. Some droplets are entrained by the airflow and follow it, while others adhere to the wall of the narrowing section and cease movement. In Region 3, after gas-liquid separation by the temperature measuring probe's turbulence structure, droplets essentially do not follow the airflow into the flow channel. The wall-attached droplets move slowly forward under the influence of the near-wall airflow and eventually detach from the wall at the probe's inlet. Some liquid enters the probe's inlet under the suction of the probe. Simultaneously, observation with endoscope 21 reveals that liquid water entering the probe's flow channel via wall-attached droplets has virtually no impact on the temperature measurement results.

[0099] This invention also provides an application of a gas phase temperature probe for high-speed, low-temperature cloud and fog fields in gas phase temperature measurement. Specific application verification has been described above.

[0100] Specifically, in the application of the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields, a temperature correction model for the temperature measurement probe was also established to correct the gas phase temperature in the high-speed low-temperature cloud and fog fields measured by the gas phase temperature measurement probe.

[0101] In the application of gas phase temperature probes, the measurement results generally differ somewhat from the actual temperature of the gas flow. This application establishes a temperature correction model for the temperature probe, which includes a restitution coefficient fitting correlation and a correction coefficient. The specific process is as follows: first, the restitution coefficient is obtained based on the restitution coefficient fitting correlation; then, the correction coefficient is obtained based on the restitution coefficient; finally, temperature correction is performed based on the correction coefficient. After temperature correction by the above-mentioned temperature probe correction model, the temperature measurement error of the temperature probe is controlled within 0.5℃, meeting the measurement accuracy requirements; and the effectiveness of the temperature correction model is verified.

[0102] Specifically, the fitting correlation of the restoration coefficient is shown in Equation 2, and the correction coefficient is shown in Equation 3:

[0103] Formula 2

[0104] Where r is the coefficient of restitution, Re h For the backward step Reynolds number, Re in T is the Reynolds number of the flow channel inside the gas phase temperature probe. r For measuring temperature using a gas phase thermography probe, ΔT r This is used to measure the difference between the temperature measured by the gas phase thermography probe and the actual temperature of the gas flow;

[0105] Formula 3

[0106] Where η is the correction coefficient, r is the restoration coefficient, and C p Let V be the isobaric heat capacity of the airflow, and T be the airflow velocity. r Temperature is measured using a gas phase thermometry probe.

[0107] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A design method for a gas phase thermometry probe used in high-speed, low-temperature cloud and fog fields, characterized in that, The following steps are involved: S1. Based on the backward temperature probe configuration, combined with the backward step two-phase flow theory in the backward temperature probe configuration and the working conditions of high-speed low temperature cloud fog field, the gas-liquid separation structure configuration of the backward temperature probe is designed, and the temperature probe configuration is obtained. The temperature probe configuration is provided with a temperature sensing element detection position. S2, based on the temperature probe configuration, performs two-phase flow simulation and suction flow simulation to realize the simulation of gas-liquid flow characteristics caused by the suction flow of the temperature probe configuration in the two-phase flow field, and analyzes the simulation results to obtain relevant data of droplets in the gas and liquid entering the temperature probe configuration. S3, Analyze the relevant data of the droplets in the gas and liquid entering the temperature probe configuration. If no droplets are detected at the detection position of the temperature sensing element in the temperature probe configuration, the design of the suction flow rate of the temperature probe configuration is completed, and proceed to the next step. Otherwise, repeat the suction flow simulation in step S2 until no droplets are detected at the temperature sensing element detection position in the temperature probe configuration; S4. Perform icing numerical simulation on the temperature probe configuration to obtain the reconstructed geometric model of the icing temperature probe configuration. Based on the reconstructed geometric model of the icing temperature probe configuration, perform two-phase flow simulation. Combined with the suction flow rate of the designed temperature probe configuration, realize the simulation of the near-wall flow field change and gas-liquid flow characteristics caused by the icing temperature probe configuration in the two-phase flow field. S5, analyze the simulation results of the near-wall flow field change caused by the icing temperature probe configuration in the two-phase flow field and the simulation results of the gas-liquid flow characteristics, and obtain the relevant data of the liquid droplets in the gas and liquid entering the icing temperature probe configuration. S6, Analyze the relevant data of liquid droplets in the gas and liquid in the temperature probe configuration after freezing. If no droplets are detected at the detection position of the temperature sensing element in the temperature probe configuration after freezing, the design is complete. Otherwise, repeat steps S1-S5 until no droplets are detected at the temperature sensing element detection position in the frozen temperature probe configuration.

2. The design method for a gas phase thermometry probe for high-speed, low-temperature cloud and fog fields according to claim 1, characterized in that, In S1, the gas-liquid separation structure configuration of the temperature measuring probe, based on the backward temperature probe configuration, combined with the backward step two-phase flow theory and the working conditions of high-speed low-temperature cloud and fog fields, specifically includes: Based on the backward temperature probe configuration, and considering the motion state of droplets in the airflow during the backward step two-phase flow in the backward temperature probe configuration, and based on the droplet size and velocity, the maximum backward step height in the gas-liquid separation structure configuration of the temperature probe is calculated, and then the gas-liquid separation structure configuration of the temperature probe is designed.

3. The design method of the gas phase thermometry probe for high-speed low-temperature cloud and fog fields according to claim 1, characterized in that, In S4, the icing numerical simulation includes: calculating the airflow field based on the initial grid and combining it with the droplet impact calculation to obtain the icing calculation of the temperature probe wall, realizing the boundary reconstruction of the icing model, and then obtaining the reconstructed geometric model of the temperature probe configuration after icing; at the same time, it is determined whether the icing time in the icing numerical simulation process reaches the set temperature probe configuration usage time. If it does, the simulation ends; otherwise, the above icing numerical simulation steps are repeated until the icing time in the icing numerical simulation process reaches the set temperature probe configuration usage time.

4. The design method of the gas phase thermometry probe for high-speed low-temperature cloud and fog fields according to claim 3, characterized in that, In S4, the two-phase flow simulation based on the reconstructed geometric model of the icing-out temperature probe configuration, combined with the suction flow rate of the designed temperature probe configuration, is used to simulate the near-wall flow field changes caused by the icing-out temperature probe configuration in the two-phase flow field. Specifically, in the two-phase flow simulation, based on the suction flow rate of the designed temperature probe configuration, and considering the shear layer and separation vortex of the droplets flowing in the near-wall flow field of the icing-out temperature probe configuration in the two-phase flow, the LES-WALE turbulence model is used to simulate and calculate the near-wall flow field of the icing-out temperature probe configuration.

5. The design method of the gas phase thermometry probe for high-speed low-temperature cloud and fog fields according to claim 4, characterized in that, The LES-WALE turbulence model includes the large eddy model and the WALE model. The large eddy model is used to model and calculate the large eddy in the separated eddy while modeling the small eddy in the separated eddy. The WALE model is used to optimize the simulation calculation of the near-wall flow field of the icing temperature probe configuration and to correct the turbulent viscosity of the shear layer.

6. The design method for a gas phase thermometry probe for high-speed low-temperature cloud and fog fields according to claim 1, characterized in that, In S5, the simulation results of the near-wall flow field changes and gas-liquid flow characteristics caused by the icing-out temperature probe configuration in the two-phase flow field also include: acquiring and analyzing the flow field diagram of the icing-out temperature probe configuration; if there is no disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration, then continue to analyze the relevant data of droplets in the gas and liquid entering the icing-out temperature probe configuration, and determine whether droplets are detected at the temperature sensing element detection position in the icing-out temperature probe configuration; if there is a disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration, then repeat steps S1-S4 until there is no disturbed droplet distribution boundary line in the flow field diagram of the icing-out temperature probe configuration.

7. The design method of the gas phase thermometry probe for high-speed low-temperature cloud and fog fields according to any one of claims 1-6, characterized in that, The design method for a gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields further includes: after S6, performing a strength check on the designed temperature measurement probe configuration. The strength check on the designed temperature measurement probe configuration specifically includes: simulating the time-averaged flow field of the temperature measurement probe configuration at 160 m / s, extracting the pressure distribution results on the wall of the temperature measurement probe configuration, performing transient stress calculation and equivalent stress calculation based on the pressure distribution results on the wall of the temperature measurement probe configuration, evaluating the stress results of the temperature measurement probe, and then determining whether the structural strength of the temperature measurement probe meets the requirements.

8. A gas phase temperature probe for high-speed, low-temperature cloud and fog fields, characterized in that, The gas phase temperature probe for high-speed low-temperature cloud and fog fields is designed using the design method of any one of claims 1-7. The gas phase temperature probe includes a hollow variable diameter bend, which includes a small-diameter hollow tube and a large-diameter hollow bend connected to one end thereto. A backward step is provided at the connection between the small-diameter hollow tube and the large-diameter hollow bend. A probe air inlet is provided at the end of the small-diameter hollow tube away from the large-diameter hollow bend, forming a gas-liquid separation structure. A temperature sensing element is provided in the large-diameter hollow bend at a position away from the small-diameter hollow tube.

9. An application of a gas phase thermometry probe for high-speed, low-temperature cloud and fog fields, characterized in that, The gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields designed based on the design method of the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields according to any one of claims 1-7, and the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields according to claim 8, are applied in gas phase temperature measurement in high-speed low-temperature cloud and fog fields.

10. The application according to claim 9, characterized in that, The application also includes: establishing a temperature correction model for the temperature measuring probe, which is used to correct the gas phase temperature in the high-speed low-temperature cloud and fog field measured by the gas phase temperature measuring probe used for the high-speed low-temperature cloud and fog field.

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