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

Abstract

The invention relates to the technical field of flow field temperature testing, in particular to a gas phase temperature measuring probe for a high-speed low-temperature cloud field and a design method and application of the gas phase temperature measuring probe. The design method of the gas phase temperature measurement probe for the high-speed low-temperature cloud field comprises the following steps: designing a temperature measurement probe configuration on the basis of a backward temperature measurement probe configuration in combination with a backward step two-phase flow theory in the backward temperature measurement probe configuration and working conditions of the high-speed low-temperature cloud field; secondly, two-phase flow simulation and suction flow simulation are carried out based on the temperature measurement probe configuration, and suction flow is designed; thirdly, icing numerical simulation is carried out, and two-phase flow simulation is carried out; and finally, analyzing the simulation result of the near-wall flow field change of the iced temperature measurement probe configuration and the simulation result of the gas-liquid flow characteristics, and if no liquid drop is monitored at the detection position of the temperature sensing element in the iced temperature measurement probe configuration, completing the design; otherwise, repeating the above steps until no liquid drop is monitored at the detection position of the temperature sensing element in the frozen temperature measurement probe configuration.

Description

Technical Field

[0001] The invention relates to the technical field of flow field temperature testing, and in particular to a gas phase temperature measuring probe for a high-speed low-temperature cloud field and a design method and application thereof. Background Art

[0002] Based on the icing wind tunnel, conducting experimental research on simulated icing cloud and fog environment is the key to conducting research and assessment on the icing characteristics of engines and aircraft. The difficulty of accurately simulating high-altitude icing cloud and fog environment involves many fields. At present, there are still many technical problems to be overcome, and the measurement of two-phase flow field parameters is the key. Among them, airflow temperature is one of the key points of two-phase flow field parameter measurement. This parameter quantifies the inertia and thermal energy of the flow and characterizes the state of gas-liquid two-phase flow. The airflow temperature also has a certain influence on the wall-impacting icing characteristics of supercooled droplets, and is an important parameter in the icing experiment. In the high-speed and low-temperature two-phase flow generated by the icing wind tunnel, the diffusion and distribution characteristics of the gas phase flow field and the droplet group are relatively more complex and changeable, making the heat exchange process between the airflow, droplets and ice crystals more difficult to predict. Therefore, accurate measurement of the gas phase temperature is the key to conducting research on icing mechanism and anti-icing technology.

[0003] In the experiments related to 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 mixed in the incoming flow makes it impossible for the temperature sensing element to directly measure the pure airflow temperature; at the same time, the characteristics of supercooled droplets hitting the wall and freezing further restrict the use of temperature sensing elements. At present, domestic and foreign research on the measurement technology of cloud and fog field parameters in icing wind tunnels mainly focuses on droplet parameters such as MVD and LWC, or other airflow parameter measurements under two-phase conditions; the research on the gas phase temperature measurement method in the low-temperature gas-liquid two-phase flow environment is still insufficient, and there is no mature method to eliminate the interference of supercooled droplets in the cloud and fog field of icing wind tunnels during temperature measurement.

[0004] From the current development status of gas-liquid two-phase flow gas-phase temperature measurement probes, it can be seen that since the contact temperature measurement method is relatively more accurate and responds faster, current research aims to design a temperature measurement probe that can separate the gas and liquid in the two-phase flow. Some research has been conducted in China, but the results obtained are only applicable to low-speed and normal-temperature gas-liquid two-phase flow environments such as rainy areas, and cannot be used in low-temperature and high-speed cloud and fog fields in icing wind tunnels; NASA and other foreign institutions have designed and tested temperature measurement probes based on icing wind tunnels, but the temperature measurement probes all have problems such as inconsistent applicable working conditions and large temperature measurement errors. Therefore, it is necessary to conduct research on the design of gas-phase temperature measurement probes for high-speed and low-temperature cloud and fog fields based on the working conditions of domestic icing wind tunnels.

[0005] Among the existing two-phase flow temperature probes, the backward temperature probe (RFP) was tested in an icing wind tunnel experiment, and the results showed that the structure has a certain gas-liquid separation effect. However, there is little data related to this probe, and the specific structural dimensions, design ideas and actual usage conditions are still unclear. In addition, the wind speed range of domestic icing wind tunnels is 50-160 m / s, and this temperature probe has only passed the test under conditions where the air speed is higher than 80m / s and the relative humidity is lower than 35%. Its applicable working conditions do not cover all working conditions of domestic icing wind tunnels. Therefore, based on this probe, the optimization design was re-performed, the design ideas were improved, the applicable working conditions were clarified and expanded, the gas-liquid separation effect of the temperature probe was optimized, and finally a temperature probe suitable for domestic icing wind tunnel working conditions was obtained. Summary of the invention

[0006] The purpose of the present invention is to provide a design method for a gas phase temperature measuring probe for a high-speed low-temperature cloud fog field, so as to solve the problems in the prior art that the backward temperature measuring probe has poor gas-liquid separation effect and few applicable working conditions.

[0007] In order to solve the above problems, the present invention proposes a design method for a gas phase temperature measurement probe for a high-speed low-temperature cloud fog field. The technical solution adopted is: The design method of a gas phase temperature measurement probe for a high-speed low-temperature cloud fog field includes the following steps: S1, based on the backward temperature measuring probe configuration, combined with the backward step two-phase flow theory in the backward temperature measuring probe configuration and the high-speed low-temperature cloud and fog field working conditions, the gas-liquid separation structure configuration of the backward temperature measuring probe is designed, and then the temperature measuring probe configuration is obtained, and a temperature sensing element detection position is set in the temperature measuring probe configuration; S2, performing two-phase flow simulation and suction flow simulation based on the temperature measuring probe configuration, realizing the simulation of gas-liquid flow characteristics caused by the suction flow of the temperature measuring probe configuration in the two-phase flow field, and analyzing the simulation results to obtain relevant data of droplets in the gas-liquid entering the temperature measuring probe configuration; S3, analyzing the relevant data of the droplets in the gas-liquid entering the temperature measuring probe configuration. If no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration, the suction flow design of the temperature measuring probe configuration is completed, and the next step is entered; Otherwise, repeat the suction flow simulation in step S2 until no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration; S4, performing a freezing numerical simulation on the temperature measuring probe configuration to obtain a reconstructed geometric model of the temperature measuring probe configuration after freezing, and performing a two-phase flow simulation based on the reconstructed geometric model of the temperature measuring probe configuration after freezing, and combining the suction flow rate of the designed temperature measuring probe configuration to achieve a simulation of the near-wall flow field changes and a simulation of the gas-liquid flow characteristics caused by the temperature measuring probe configuration after freezing in the two-phase flow field; S5, analyzing the simulation results of the change of the near-wall flow field caused by the temperature measuring probe configuration after freezing in the two-phase flow field and the simulation results of the gas-liquid flow characteristics, and obtaining relevant data of the droplets in the gas and liquid entering the temperature measuring probe configuration after freezing; S6, analyzing the data related to the droplets in the gas-liquid in the temperature measuring probe configuration after freezing, if no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration after freezing, the design is completed; Otherwise, steps S1-S5 are repeated until no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration after freezing. Further, in S1, based on the backward temperature measuring probe configuration, combined with the backward step two-phase flow theory and the high-speed low-temperature cloud and fog field working conditions, the gas-liquid separation structure configuration of the temperature measuring probe is designed specifically including: 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 in the backward temperature measuring probe configuration, and based on the particle size and velocity of the droplets, the maximum backward step height in the gas-liquid separation structural configuration of the temperature measuring probe is calculated, and then the gas-liquid separation structural configuration of the temperature measuring probe is obtained.

[0008] Furthermore, in S4, the numerical simulation of ice formation includes: calculating the airflow field based on the initial grid, and combining the calculation of droplet impacting the wall to obtain the ice formation calculation of the temperature probe wall, realizing the boundary reconstruction of the ice model, and then obtaining the reconstructed geometric model of the temperature probe configuration after ice formation; at the same time, determining whether the freezing time in the ice formation numerical simulation process reaches the set usage time of the temperature probe configuration, if so, the simulation ends; otherwise, repeating the above-mentioned ice formation numerical simulation steps until the freezing time in the ice formation numerical simulation process reaches the set usage time of the temperature probe configuration.

[0009] Furthermore, in S4, the two-phase flow simulation is performed based on the reconstructed geometric model of the temperature probe configuration after freezing, and the suction flow rate of the designed temperature probe configuration is combined to realize the simulation of the near-wall flow field changes caused by the temperature probe configuration after freezing in the two-phase flow field. Specifically, the LES-WALE turbulence model is used to simulate and calculate the near-wall flow field of the temperature probe configuration after freezing, based on the shear layer and separation vortex of the droplets in the two-phase flow flowing in the near-wall flow field of the temperature probe configuration after freezing.

[0010] 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 eddy in the separation vortex while modeling the small eddy in the separation vortex; the WALE model is used to optimize the simulation calculation of the near-wall flow field of the temperature measuring probe configuration after freezing, and to correct the turbulent viscosity of the shear layer.

[0011] Furthermore, in S5, the simulation results of analyzing the changes in the near-wall flow field caused by the temperature measuring probe configuration after freezing in the two-phase flow field and the simulation results of the gas-liquid flow characteristics also include: obtaining and analyzing the flow field diagram of the temperature measuring probe configuration after freezing; if there is no disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, then continuing to analyze the relevant data of droplets in the gas and liquid entering the temperature measuring probe configuration after freezing, and judging whether droplets are monitored at the temperature sensing element detection position in the temperature measuring probe configuration after freezing; if there is a disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, then repeating steps S1-S4 until there is no disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing.

[0012] Furthermore, the design method of the gas phase temperature measuring probe for high-speed low-temperature cloud field also includes: after S6, performing strength verification on the designed temperature measuring probe configuration, and the strength verification on the designed temperature measuring probe configuration specifically includes: simulating the time-averaged flow field of the temperature measuring probe configuration at 160 m / s, and extracting the wall pressure distribution result of the temperature measuring probe configuration, performing transient stress calculation and equivalent stress calculation based on the wall pressure distribution result of the temperature measuring probe configuration, evaluating the force result of the temperature measuring probe, and then judging whether the structural strength of the temperature measuring probe meets the requirements.

[0013] Beneficial effects: The present invention is an improved invention, which proposes a design method for a gas-phase temperature measuring probe for a high-speed, low-temperature cloud fog field. The gas-liquid separation structure of the backward temperature measuring probe is designed in combination with the working conditions of the high-speed, low-temperature cloud fog field, and the structural design of the temperature measuring probe configuration after freezing is obtained in combination with the icing numerical simulation, thereby solving the coupling problem between icing calculation and two-phase flow field calculation, so that the temperature measuring probe designed by the present invention improves the gas-liquid separation effect and reduces the influence of icing on the wall of the temperature measuring probe on the temperature measurement accuracy. At the same time, different gas-phase temperature measuring probes for high-speed, low-temperature cloud fog fields can be designed according to different domestic icing wind tunnel working conditions, so that it has a wide range of applications. In conventional numerical simulations of freezing, it is impossible to obtain the trajectory of droplet motion, and therefore it is impossible to know the gas-liquid separation effect of the temperature probe; and the ice shape results of the freezing calculation cannot be used directly for two-phase flow field calculations. Therefore, the design method of the present invention reconstructs the geometric model of the temperature probe after freezing through numerical simulations of freezing, solves the coupling problem between freezing calculations and two-phase flow field calculations, performs two-phase flow simulation based on the reconstructed temperature probe model after freezing, and combines the suction flow obtained by the design to obtain the gas-liquid separation results of the temperature probe after freezing. At the same time, the critical thickness of ice on the wall of the temperature probe configuration can be determined in the present invention through numerical simulations of freezing, which provides a time reference for the normal use of the temperature probe in an icy foggy environment, and helps to reduce the problem of probe failure caused by freezing.

[0014] The present invention also provides a gas phase temperature measuring probe for a high-speed, low-temperature cloud fog field. The design method for the above-mentioned gas phase temperature measuring probe for a high-speed, low-temperature cloud fog field is designed, including a hollow reducer bend, the hollow reducer bend includes a small diameter hollow tube and a large diameter hollow bend connected to one end thereof, 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 on the end of the small diameter hollow tube away from the large diameter hollow bend to form a gas-liquid separation structure configuration, and a temperature sensing element is provided at a position in the large diameter hollow bend away from the small diameter hollow tube.

[0015] Beneficial effects: The gas-phase temperature measuring probe for high-speed, low-temperature cloud and fog fields of the present invention can be applied to multiple working conditions of domestic icing wind tunnels; at the same time, the gas-liquid separation effect of the gas-phase temperature measuring probe is improved, and the influence of wall icing on the temperature measurement accuracy is reduced. In addition, the gas-phase temperature measuring probe for high-speed, low-temperature cloud and fog fields of the present invention can be used to carry out visualization experiments, using a high-speed camera to photograph the air inlet of the temperature measuring probe. When no droplets are found to follow the air flow into the flow channel inside the temperature measuring probe, a temperature measurement experiment is carried out, and the temperature measurement curve of the temperature measuring probe under different working conditions is analyzed. It can be concluded that the temperature measured by the temperature measuring probe is the gas phase temperature, and the gas-liquid separation effect is good. Accurate gas phase temperature measurement is achieved within the target working condition range.

[0016] The present invention also provides an application of a gas phase temperature measuring probe for a high-speed low-temperature cloud fog field, a gas phase temperature measuring probe for a high-speed low-temperature cloud fog field designed based on the above-mentioned design method of the gas phase temperature measuring probe for a high-speed low-temperature cloud fog field, and the application of the above-mentioned gas phase temperature measuring probe for a high-speed low-temperature cloud fog field in gas phase temperature measurement in a high-speed low-temperature cloud fog field.

[0017] Beneficial effects: The application of the gas phase temperature measuring probe for high-speed low-temperature cloud fog field provided by the present invention in the gas phase temperature measurement in the high-speed low-temperature cloud fog field has a wide range of applications and good gas-liquid separation effect.

[0018] Furthermore, the application also includes: establishing a temperature correction model for a temperature measuring probe, which is used to correct the gas phase temperature in a high-speed low-temperature cloud field measured by a gas phase temperature measuring probe used for the high-speed low-temperature cloud field.

[0019] In S1, the design of the gas-liquid separation structure configuration of the temperature measuring probe based on the backward temperature measuring probe configuration, combined with the backward step two-phase flow theory and the high-speed low-temperature cloud field working conditions 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 in the backward temperature measuring probe configuration, and based on the particle size and velocity of the droplets, the maximum backward step height in the gas-liquid separation structure configuration of the temperature measuring probe is calculated, and then the gas-liquid separation structure configuration of the temperature measuring probe is designed; by determining the maximum backward step height, droplets are effectively prevented from entering the temperature measurement area, thereby ensuring the effectiveness of gas-liquid separation.

[0020] In S4, the icing numerical simulation includes: calculating the airflow field based on the initial grid, and combining the droplet impact calculation to obtain the temperature probe wall icing calculation, realizing the reconstruction of the icing model boundary, and then obtaining the reconstructed geometric model of the temperature probe configuration after icing; at the same time, determining whether the icing time during the icing numerical simulation process reaches the set temperature probe configuration use time, if so, the simulation ends; otherwise, repeating the above icing numerical simulation steps until the icing time during the icing numerical simulation process reaches the set temperature probe configuration use time. Through the above high-precision geometric reconstruction method, the geometric model of the temperature probe after icing is reconstructed, solving the coupling problem between icing calculation and two-phase flow field calculation.

[0021] In S4, the two-phase flow simulation is performed based on the reconstructed geometric model of the temperature probe configuration after freezing, and the suction flow rate of the designed temperature probe configuration is combined to realize the simulation of the near-wall flow field changes caused by the temperature probe configuration after freezing in the two-phase flow field. Specifically, the LES-WALE turbulence model is used to simulate the near-wall flow field of the temperature probe configuration after freezing, based on the shear layer and separation vortex of the droplets in the two-phase flow flowing in the near-wall flow field of the temperature probe configuration after freezing, thereby improving the calculation accuracy and efficiency, and obtaining more accurate flow field calculation results.

[0022] 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 eddy in the separation vortex while modeling the small eddy in the separation vortex. Both large and small vortex structures are considered at the same time. The small eddy is modeled while the large eddy is modeled to improve the calculation accuracy. The WALE model is used to optimize the simulation calculation of the near-wall flow field of the temperature measuring probe configuration after freezing, and to correct the turbulent viscosity of the shear layer, so that the calculation in the laminar and shear flow regions is more accurate.

[0023] In S5, the simulation results of analyzing the changes in the near-wall flow field caused by the temperature measuring probe configuration after freezing in the two-phase flow field and the simulation results of the gas-liquid flow characteristics also include: obtaining and analyzing the flow field diagram of the temperature measuring probe configuration after freezing; if there is no disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, then continuing to analyze the relevant data of droplets in the gas and liquid entering the temperature measuring probe configuration after freezing, and judging whether droplets are monitored at the temperature sensing element detection position in the temperature measuring probe configuration after freezing; if there is a disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, then repeating steps S1-S4 until there is no disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, so as to preliminarily judge the separation effect of the temperature measuring probe configuration, and enhance the convenience and accuracy of judging the separation effect.

[0024] The design method of the gas phase temperature measuring probe for high-speed low-temperature cloud fog field also includes: after S6, performing strength verification on the designed temperature measuring probe configuration, and the strength verification on the designed temperature measuring probe configuration specifically includes: simulating the time-averaged flow field of the temperature measuring probe configuration at 160 m / s, and extracting the wall pressure distribution result of the temperature measuring probe configuration, performing transient stress calculation and equivalent stress calculation based on the wall pressure distribution result of the temperature measuring probe configuration, evaluating the force result of the temperature measuring probe, and then judging whether the structural strength of the temperature measuring probe meets the requirements, so as to ensure the practicability of manufacturing the gas phase temperature measuring probe for high-speed low-temperature cloud fog field.

[0025] The application also includes: establishing a temperature correction model for a temperature measuring probe, which is used to correct the gas phase temperature in a high-speed low-temperature cloud field measured by a gas phase temperature measuring probe used in a high-speed low-temperature cloud field, and establishing a temperature correction model that takes into account factors such as turbulence, suction and wall heat transfer, thereby improving the temperature measurement accuracy. As a result, after the temperature is corrected by the temperature correction model, the temperature measurement error of the temperature measuring probe is controlled within 0.5°C, meeting the measurement accuracy requirements. At the same time, the effectiveness of the temperature correction model is verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the temperature measurement principle of the temperature measurement probe configuration in the design method of the gas phase temperature measurement probe for high-speed low-temperature cloud fog field of the present invention; Figure 2 It is a structural schematic diagram 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; Figure 3 It is a structural schematic diagram of a temperature measuring probe configuration separation effect monitoring point in a design method of a gas phase temperature measuring probe for a high-speed low-temperature cloud fog field of the present invention; Figure 4 It is a schematic diagram of the motion state of liquid droplets entrained in the airflow in the configuration of the temperature measuring probe in the design method of the gas phase temperature measuring probe for high-speed low-temperature cloud fog field of the present invention; Figure 5 It is a schematic diagram of four different temperature measuring probe configuration structures in the design method of the gas phase temperature measuring probe for high-speed low-temperature cloud fog field of the present invention; Figure 6 It is the statistical result of the liquid inflow of four different temperature measuring probe configurations in the design method of the gas phase temperature measuring probe for high-speed low-temperature cloud fog field of the present invention; Figure 7 It is the comparison result of droplet distribution of four different temperature measuring probe configurations in the design method of the gas phase temperature measuring probe for high-speed low-temperature cloud fog field of the present invention; Figure 8It is a planar droplet distribution diagram in the v-axis direction in the process of the design method of the gas phase temperature measurement probe for high-speed low-temperature cloud fog field of the present invention; Fig. 9 It is the calculation result of the configuration stress of the temperature measuring probe in the design method of the gas phase temperature measuring probe for high-speed low-temperature cloud and fog field of the present invention; Fig.10 It is a schematic diagram of the placement of a high-speed camera during the verification process of the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields of the present invention; Fig.11 It is a schematic diagram of the shooting area of ​​the gas phase temperature measurement probe used for high-speed low-temperature cloud and fog fields during the verification process of the present invention; Fig.12 It is a schematic diagram of the installation of a pipeline 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; In the figure, 1. two-phase incoming flow, 2. pure air flow, 3. temperature sensing element, 4. suction pipeline, 5. vacuum pump, 6. small diameter hollow tube, 7. large diameter hollow elbow, 8. backward step, 9. separation vortex, 10. shear layer, 11. time-averaged boundary, 12. reattachment layer, 13. duct outlet, 14. light source, 15. high-speed camera, 16. low-temperature gas-liquid two-phase flow, 17. control group probe, 18. laboratory flow outlet, 19. monitoring area, 20. suction flow channel, 21. endoscope. DETAILED DESCRIPTION

[0027] As cited in the background art, the gas-liquid separation effect of the backward temperature measuring probe in the prior art is poor and its applicable working conditions are limited. Therefore, the present invention provides a design method for a gas-phase temperature measuring probe for a high-speed low-temperature cloud fog field, comprising the following steps: first, based on the backward temperature measuring probe configuration, combined with the backward step two-phase flow theory in the backward temperature measuring probe configuration and the working conditions of the high-speed low-temperature cloud fog field, the gas-liquid separation structure configuration of the backward temperature measuring probe is designed, and then the temperature measuring probe configuration is obtained, and a temperature sensing element detection position is provided in the temperature measuring probe configuration, which is used to obtain different temperature measuring probe configurations under different high-speed low-temperature cloud fog field working conditions; secondly, based on the temperature measuring 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 measuring probe configuration in the two-phase flow field, and the suction flow of the temperature measuring probe configuration is designed for subsequent two-phase flow simulation; then, the temperature measuring probe configuration is subjected to an icing numerical simulation to obtain a reconstructed geometric model of the temperature measuring probe configuration after icing, and a two-phase flow simulation is performed based on the reconstructed geometric model of the temperature measuring probe configuration after icing, and the icing is realized in combination with the suction flow of the designed temperature measuring probe configuration. The simulation of the changes in the near-wall flow field and the simulation of the gas-liquid flow characteristics caused by the temperature probe configuration after ice in the two-phase flow field are used to solve the coupling problem between the ice calculation and the two-phase flow field calculation; finally, the simulation results of the changes in the near-wall flow field and the simulation results of the gas-liquid flow characteristics caused by the temperature probe configuration after ice in the two-phase flow field are analyzed, and the relevant data of the droplets in the gas and liquid in the temperature probe configuration after ice are obtained to judge the gas-liquid separation effect analysis; the relevant data of the droplets in the gas and liquid in the temperature probe configuration after ice are analyzed, if no droplets are detected at the temperature sensing element detection position in the temperature probe configuration after ice, the design is completed; otherwise, repeat the first 5 steps until no droplets are detected at the temperature sensing element detection position in the temperature probe configuration after ice, so that the temperature probe designed by it improves the gas-liquid separation effect and reduces the influence of ice on the temperature measurement accuracy of the temperature probe wall; at the same time, different gas-phase temperature probes for high-speed, low-temperature fog fields are designed according to different domestic icing wind tunnel working conditions, so that it has a wide range of applications.

[0028] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] The following describes a gas phase temperature measurement probe for a high-speed low-temperature cloud field and its design method and application according to an embodiment of the present application with reference to the accompanying drawings.

[0030] Combine the following Figure 1 , the design method of the gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields provided in this application is described in detail.

[0031] like Figure 1 and Figure 2 As shown, the design method of the gas phase temperature measuring probe for the high-speed low-temperature cloud fog field includes the following steps: first, based on the backward temperature measuring probe configuration, combined with the backward step two-phase flow theory in the backward temperature measuring probe configuration and the working conditions of the high-speed low-temperature cloud fog field, the gas-liquid separation structure configuration of the backward temperature measuring probe is designed, and then the temperature measuring probe configuration is obtained, and a temperature sensing element is arranged in the temperature measuring probe configuration; secondly, based on the temperature measuring 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 measuring probe configuration in the two-phase flow field, and the simulation results are analyzed to obtain the relevant data of the droplets in the gas and liquid entering the temperature measuring probe configuration; then, the relevant data of the droplets in the gas and liquid entering the temperature measuring probe configuration are analyzed. If no droplets are detected at the detection position of the temperature sensing element in the temperature measuring probe configuration, the suction flow design of the temperature measuring probe configuration is completed, and the next step is entered; otherwise, the suction flow simulation in the previous step is repeated until the suction flow in the temperature measuring probe configuration is detected. No droplets are detected at the temperature element detection position; then, a freezing numerical simulation is performed on the temperature measuring probe configuration to obtain a reconstructed geometric model of the temperature measuring probe configuration after freezing, and a two-phase flow simulation is performed based on the reconstructed geometric model of the temperature measuring probe configuration after freezing, and the suction flow rate of the designed temperature measuring probe configuration is combined to achieve the simulation of the near-wall flow field changes and the gas-liquid flow characteristics caused by the temperature measuring probe configuration after freezing in the two-phase flow field; finally, the simulation results of the near-wall flow field changes and the gas-liquid flow characteristics caused by the temperature measuring probe configuration after freezing in the two-phase flow field are analyzed to obtain the relevant data of the droplets in the gas and liquid in the temperature measuring probe configuration after freezing; the relevant data of the droplets in the gas and liquid in the temperature measuring probe configuration after freezing are analyzed, and if no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration after freezing, the design is completed; otherwise, the previous 5 steps are repeated until no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration after freezing. Specifically, if Figure 3 As shown, in the simulated temperature measuring probe configuration, four monitoring points of Plane1, Plane2, Plane3 and Plane4 are designed, among which the Plane4 monitoring point is the detection position of the temperature sensing element set in the temperature measuring probe configuration. If the Plane4 monitoring point does not detect the passage of droplets, the design is completed.

[0032] In a specific embodiment of the present application, based on the backward temperature measuring probe configuration, combined with the backward step two-phase flow theory and the high-speed and low-temperature cloud field operating conditions, the gas-liquid separation structure configuration of the temperature measuring probe is designed specifically including: 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 in the backward temperature measuring probe configuration, and based on the particle size and velocity of the droplets, the maximum backward step height in the gas-liquid separation structure configuration of the temperature measuring probe is calculated, and then the gas-liquid separation structure configuration of the temperature measuring probe is designed.

[0033] Specifically, the temperature measurement principle of the backward temperature measuring probe is as follows: Figure 1 and Figure 2 As shown, the backward temperature measuring probe includes a hollow reducer elbow, which includes a small diameter hollow tube 6 and a large diameter hollow elbow 7 connected to one end thereof, a backward step 8 is provided at the connection between the small diameter hollow tube 6 and the large diameter hollow elbow 7, a probe air inlet is provided at one end of the small diameter hollow tube 6 away from the large diameter hollow elbow 7, and a temperature sensing element 3 is provided at a position of the large diameter hollow elbow 7 away from the small diameter hollow tube 6. Among them, the probe air inlet is placed toward the leeward side, and after the two-phase incoming flow 1 passes through the turbulence of the temperature measuring probe, a pure airflow 2 is separated and close to the air inlet. Under the action of the vacuum pump 5, the interior of the temperature measuring probe is sucked through the suction pipeline 4, and the airflow enters the flow channel and passes through the temperature sensing element 3 to complete the temperature measurement.

[0034] In another embodiment of the present application, the gas-liquid separation effect of the temperature measuring probe configuration can be judged according to the amount of liquid entering the temperature measuring probe configuration, such as Figure 3 As shown, the liquid inlet amount of the temperature probe air inlet, that is, the liquid inlet amount of the Plane1 monitoring point, is counted. The smaller the liquid inlet amount, the better the gas-liquid separation effect of the temperature probe configuration.

[0035] In another embodiment of the present application, the amount of liquid entering through the rear step 8 in the temperature measuring probe configuration, that is, the amount of liquid entering the Plane2 monitoring point, is counted. The smaller the amount of liquid entering, the better the gas-liquid separation effect of the temperature measuring probe configuration.

[0036] In another embodiment of the present application, the amount of liquid entering through the bend on the large-diameter hollow curved pipe 7 in the temperature measuring probe configuration, that is, the amount of liquid entering the Plane3 monitoring point, is counted. The smaller the amount of liquid entering, the better the gas-liquid separation effect of the temperature measuring probe configuration.

[0037] The main structural parameters of the temperature probe configuration are as follows: Figure 2As shown, the large diameter hollow elbow 7 of the temperature probe configuration includes a main pipe, the diameter of the main pipe is D, the length of the horizontal pipe section of the main pipe is L, the outer diameter of the temperature probe air inlet is d, the length of the small diameter hollow pipe 6 is l, and the difference between the radius of the main pipe and the small diameter hollow pipe 6 of the temperature probe configuration is h, that is, the height of the rear step 8 is h. The main pipe diameter D is preliminarily determined to be 19 mm, and the remaining dimensions will be designed in the next step. The domestic icing wind tunnel working range is: air velocity 50-160 m / s, liquid water content (LWC) not exceeding 3g / m 3 , the droplet size is 15-50 μm, and the minimum incoming flow velocity is 50 m / s.

[0038] The calculation process of the maximum step height is: like Figure 4 As shown in the figure, in the flow of the backward step 8, the droplets mixed in the airflow have two motion states: one is to follow the shear layer 10 and the separation vortex 9 under the influence of the airflow; the other is to maintain its original motion trajectory. The motion state of the droplets depends on the size of the droplet Stokes number (St). This parameter characterizes the ratio of the droplet inertia and diffusion. The smaller the value, the smaller the droplet inertia, the easier it is to follow the fluid movement, and the more obvious its diffusion effect; conversely, the larger the St number, the greater the droplet inertia, and the less obvious the followability of the droplet movement. The calculation of the droplet Stokes number is shown in formula 1: Formula 1; in, , , and St>1, τ p With τ f are the characteristic time of droplet and airflow, ρ p is the droplet density, d p is the droplet size, μ f is the fluid dynamic viscosity, h is the step height, and U is the air flow velocity.

[0039] Therefore, taking the droplet size of 15 μm and the speed of 50 m / s in the wind tunnel working condition as the design working condition, the maximum height of the backward step 8 is calculated to be 7.5 mm, that is, the height h of the backward step 8 of the temperature measuring probe shall not exceed 7.5 mm. After preliminarily determining the height h of the backward step 8, simulations are carried out on temperature measuring probes with different structural dimensions, different small diameter hollow tube 6 structures, different horizontal pipe section lengths, and different temperature measuring probe suction flow rates to obtain the temperature measuring probe configuration with the best gas-liquid separation effect in theory.

[0040] Specifically, Figure 4As shown in the figure, for the design of temperature measuring probe configurations of different small diameter hollow tubes 6, in the particle flow of the backward step 8, the height and length of the backward step 8 will affect the generated separation vortex 9 and the reattachment layer 12, thereby affecting the movement trajectory of the particles. Therefore, by adjusting the diameter and length of the small diameter hollow tube 6, four different temperature measuring probe configurations are obtained for the above working conditions, and the influence of the structural dimensions of the small diameter hollow tube 6 in the temperature measuring probe configuration on the gas-liquid separation effect is studied. The specific structural parameters are as follows: Figure 5 and as shown in Table 1. The four temperature probe configurations were simulated under the same typical working conditions. The specific working parameters were: initial gas velocity (droplet velocity) 80 m / s, LWC = 3 g / m 3 , initial air temperature 268K, droplet temperature 273K, droplet size 1-50 μm, suction flow rate 3 slpm (standard liters per minute). From the flow field and droplet distribution, it can be seen that in the backward step flow process, most of the high-speed droplets move forward under the action of inertia, and a small number of droplets with lower speed and extremely small particle size follow the airflow for shear separation flow; among them, a part of the droplets are captured by the separation vortex 9 structure and make a cyclotron motion at the bottom of the step; a part of the droplets follow the separation layer and flow close to the wall to the vicinity of the flow channel entrance, and some of the droplets enter the flow channel in the temperature probe configuration under the action of suction. The number of droplets entering the flow channel represents the quality of 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 counted, and the statistical results of the liquid inflow of each configuration are shown in Figure 6.

[0041] Table 1 Specific structural parameters of four different temperature probe configurations

[0042] The results show that all four structures have a certain amount of liquid inflow, but no droplets were detected passing through the location where the temperature sensing element is set. This shows that even if the droplets follow the airflow into the flow channel of the temperature measuring probe, they will hit the wall and attach to the wall before passing through the curved pipe section, making it difficult to reach the area where the temperature sensing element is located at the rear. Therefore, the above four structural designs are all acceptable. If the optimal structural design is to be selected, according to statistical results, the temperature measuring probe of Type 1 configuration has the smallest amount of liquid inflow, and the particle size of the droplets entering the flow channel is less than 1 μm. Under actual working conditions, the number of droplets with a particle size less than 1 μm is extremely small, and the mass of the liquid is very small, and the effect on gas phase temperature measurement can be ignored. Therefore, it is believed that among the above four configurations, the mass of droplets entering the Type 1 flow channel is the least, and the gas-liquid separation effect is the best under the working conditions of the icing wind tunnel. Therefore, the structure of the small diameter hollow tube 6 in the temperature measuring probe configuration design is selected from the structure of the small diameter hollow tube 6 in Type 1.

[0043] For the design of different horizontal pipe section lengths, when the airflow passes through the vertical pipe section of the temperature probe, a vortex will be generated at the rear. If the distance between the air inlet of the temperature probe and the vertical pipe section is too close, it may interfere with the backward step flow area at the air inlet of the temperature probe. Based on the temperature probe of configuration Type 1, the length of the horizontal pipe section of the temperature probe is changed to change the effect of the vortex on the flow field of the small diameter hollow tube 6. If the length of the horizontal pipe section of the temperature probe is too short, it will destroy the backward step flow area of ​​the reduced diameter section of the temperature probe and affect the gas-liquid separation effect. Figure 7 As shown, it can be concluded that when the outer diameter of the main pipeline is 19 mm, the horizontal pipe section length of the temperature probe must be at least 100 mm to avoid the adverse effects of vertical pipe turbulence on gas-liquid separation. However, the horizontal pipe section length of the temperature probe should not be too long to avoid excessive contact time between the airflow and the wall, which will cause the airflow temperature to change and affect the temperature measurement accuracy.

[0044] In a specific embodiment of the present application, two-phase flow simulation and suction flow simulation are performed based on the temperature measuring probe configuration to achieve simulation of the gas-liquid flow characteristics caused by the suction flow of the temperature measuring 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 measuring probe configuration; the relevant data of droplets in the gas and liquid entering the temperature measuring probe configuration are analyzed, and if no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration, the suction flow design of the temperature measuring probe configuration is completed, and the next step is entered; otherwise, the suction flow simulation in the previous step is repeated until no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration.

[0045] Specifically, without considering the flow of droplets attached to the wall, the suction of the temperature probe is the most important factor causing the droplets to enter the flow channel. When the suction flow rate increases, more droplets are attracted, changing the trajectory of movement, and increasing the probability of droplets entering the air inlet of the temperature probe. Under the above working conditions, when the suction flow rate increases, the airflow velocity in the flow channel of the temperature probe configuration increases significantly, and the influence range of the suction on the external flow field of the temperature probe configuration also increases significantly; at the same time, as the air velocity in the flow channel of the temperature probe configuration increases, the heat exchange between the airflow and the temperature sensing element is more sufficient, the heat exchange efficiency is higher, and the time required for the temperature probe configuration to establish temperature equilibrium can be shortened. However, as the suction flow rate increases, more droplets are attracted, changing the trajectory of movement, increasing the probability of droplets entering the air inlet of the temperature probe configuration, and the liquid inlet amount of the temperature probe configuration air inlet increases significantly. Therefore, when simulating the suction flow design of the temperature probe configuration, under a certain suction flow, it is determined whether the suction flow design of the temperature probe configuration is completed by judging whether droplets are detected at the temperature sensing element detection position in the temperature probe configuration. It can be concluded that the suction flow of the temperature probe configuration obtained under the above working conditions should not exceed 90slpm to avoid sucking too many droplets into the flow channel.

[0046] At the same time, since operating parameters such as gas flow rate, liquid water content, and droplet particle size will affect the final gas-liquid separation effect when the temperature probe performs gas-liquid separation, multiple groups of different operating conditions are set based on the above parameters, and temperature probe configurations with various 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 working conditions. The design method of the present application can design different gas phase temperature measuring probes for high-speed, low-temperature cloud fields according to different domestic icing wind tunnel working conditions, making it have a wide range of applications.

[0047] In a specific embodiment of the present application, the numerical simulation of ice formation includes: calculating the airflow field based on the initial grid, and combining the droplet impact calculation to obtain the ice formation calculation of the temperature probe wall, realizing the reconstruction of the ice model boundary, and then obtaining the reconstructed geometric model of the temperature probe configuration after ice formation; at the same time, determining whether the ice formation time during the ice formation numerical simulation process reaches the set use time of the temperature probe configuration, if so, the simulation ends; otherwise, repeating the above ice formation numerical simulation steps until the ice formation time during the ice formation numerical simulation process reaches the set use time of the temperature probe configuration. Specifically, the method for numerical simulation of ice formation on the temperature probe wall is: firstly, calculating the airflow field based on the initial grid, then adding droplets to perform calculations, obtaining the droplet impact distribution results, and performing ice formation calculations based on this to obtain the final ice shape, and detecting and determining whether the ice formation time during the ice formation numerical simulation process reaches the set use time of the temperature probe configuration, otherwise, repeating the above steps until the calculation is completed. The icing calculation is based on Fensap-ice software, which can be coupled with Fluent for calculation. Therefore, when simulating icing numerically, the airflow field is first calculated in Fluent, and then Fensap-ice is imported to calculate the droplets, and icing settlement is performed to realize icing simulation.

[0048] In the simulation of water droplet impact characteristics, the Euler method regards the droplets in the airflow as a continuous phase and focuses on controlling the changes in the droplets in the body. This is more advantageous when solving three-dimensional complex configuration surfaces and has higher solution efficiency. Therefore, the Euler method is used as the droplet solution algorithm. In the high-speed low-temperature cloud field generated by the icing wind tunnel, the total volume fraction of supercooled droplets and ice crystals generally does not exceed 10%. Therefore, the discrete phase model (DPM) is used to calculate supercooled droplets. The continuous phase, i.e., the droplets in the airflow, is calculated based on the Euler method, and the discrete phase, i.e., the supercooled droplets, is calculated using the Lagrangian method. The interaction between the gas and liquid phases, the movement of the droplets, and the heat and mass transfer processes are comprehensively considered to perform a two-way coupling calculation.

[0049] In a specific embodiment of the present application, Figure 4As shown, based on the reconstructed geometric model of the temperature probe configuration after freezing, two-phase flow simulation is performed, and combined with the suction flow of the designed temperature probe configuration, the simulation of the change of the near-wall flow field caused by the temperature probe configuration after freezing in the two-phase flow field includes: in the two-phase flow simulation, combined with the suction flow of the designed temperature probe configuration, based on the shear layer 10 and the separation vortex 9 of the droplets in the two-phase flow flowing in the near-wall flow field of the temperature probe configuration after freezing, the LES-WALE turbulence model is used to simulate and calculate the near-wall flow field of the temperature probe configuration after freezing. 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 eddy in the separation vortex 9 while modeling the small eddy in the separation vortex 9; the WALE model is used to optimize the simulation calculation of the near-wall flow field of the temperature probe configuration after freezing, and to correct the turbulent viscosity of the shear layer 10.

[0050] Specifically, the near-wall flow field of the temperature probe configuration after freezing is simulated. The areas where the droplets flow in the near-wall flow field of the temperature probe configuration after freezing include the shear layer 10, the separation vortex 9, the time-averaged boundary 11 and the reattachment layer 12. In the LES, i.e., large eddy model, only the large eddy is modeled; and since small eddies tend to be more isotropic, it is easier to find a universal turbulence model and directly model them, so the large eddy model is used to calculate the near-wall flow field of the temperature probe configuration. At the same time, the WALE model is used to optimize the calculation of the near-wall flow field of the temperature probe configuration, and the turbulent viscosity in the shear layer area is corrected. Therefore, the WALE model makes the calculation of the flow area of ​​the shear layer 10 more accurate. LES models small-sized vortices, which reduces the number of grids required for its calculation and reduces the requirements for the time step, while ensuring accuracy. The use of the LES large eddy model simultaneously considers both large and small scale vortex structures. While modeling and calculating the large eddy, the small eddy is modeled, and the calculation accuracy is relatively higher, thereby obtaining more accurate flow field calculation results. Therefore, the present invention selects the LES-WALE model as the turbulence model to simulate the near-wall flow field of the temperature measuring probe configuration after freezing.

[0051] In another embodiment of the present application, analyzing the simulation results of the near-wall flow field changes caused by the temperature measuring probe configuration after freezing in the two-phase flow field and the simulation results of the gas-liquid flow characteristics also includes: obtaining and analyzing the flow field diagram of the temperature measuring probe configuration after freezing, if there is no disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, then continuing to analyze the relevant data of droplets in the gas and liquid entering the temperature measuring probe configuration after freezing, and judging whether droplets are monitored at the temperature sensing element detection position in the temperature measuring probe configuration after freezing; if there is a disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, then repeating the above steps until there is no disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing.

[0052] Specifically, Figure 8 As shown in the figure, when the temperature probe is not frozen, its droplet distribution boundary is relatively stable, showing two smooth curves. When ice accumulates on the wall of the temperature probe, an obvious boss will be formed in the z-axis direction within 60 seconds, disturbing the airflow, causing fluctuations in the droplet distribution boundary. The higher the boss, the more severe the disturbance, the more unstable the droplet distribution boundary, the larger the fluctuation amplitude, and the more serious the negative impact on the gas-liquid separation of the temperature probe. In summary, it can be seen that excessive ice on the wall of the temperature probe will disturb the near-wall airflow, causing the droplet distribution boundary to fluctuate and diffuse, and ultimately causing a negative effect on the gas-liquid separation of the temperature probe. Therefore, the separation effect can be judged in advance based on whether there is a disturbed droplet distribution boundary in the simulation flow field diagram of the near-wall flow field changes caused by the temperature probe configuration after ice formation in the two-phase flow field.

[0053] In another embodiment of the present application, the design method of a gas phase temperature measuring probe for a high-speed, low-temperature cloud field also includes: performing a strength check on the designed temperature measuring probe configuration, and the strength check on the designed temperature measuring probe configuration specifically includes: simulating the time-averaged flow field of the temperature measuring probe configuration at 160 m / s, and extracting the wall pressure distribution results of the temperature measuring probe configuration, performing transient stress calculation and equivalent stress calculation based on the wall pressure distribution results of the temperature measuring probe configuration, evaluating the force results of the temperature measuring probe, and then judging whether the structural strength of the temperature measuring probe meets the requirements.

[0054] Specifically, the high-speed incoming flow in the icing wind tunnel is relatively stable, with almost no fluctuations in velocity and pressure. Therefore, the time-averaged flow field of the temperature probe at the maximum air velocity (160 m / s) was simulated, and the pressure distribution results of the temperature probe wall were extracted to perform transient stress calculations. Based on the fourth strength theory, equivalent stress calculations were performed to evaluate the stress conditions of the temperature probe. The calculation results are shown in Figure 2. Fig. 9 As shown in the figure, it can be seen that the temperature probe is subjected to a clockwise bending moment under the impact of airflow. The stress on the wall of the temperature probe is about 13.162 MPa, and the minimum yield limit of 304 stainless steel is about 185 MPa, which is much greater than the maximum stress on the temperature probe; at the same time, the ductile-brittle transition temperature of 304 stainless steel is about -190℃, which is much lower than the experimental environment. Therefore, it can be seen that the structural strength of the temperature probe made of 304 stainless steel meets the requirements.

[0055] The present invention also provides a gas phase temperature measuring probe for a high-speed low-temperature cloud fog field, which is designed by the above-mentioned design method of the gas phase temperature measuring probe for a high-speed low-temperature cloud fog field. The gas phase temperature measuring probe includes a hollow reducer bend, and the hollow reducer bend includes a small diameter hollow tube 6 and a large diameter hollow bend 7 connected to one end thereof. 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 one end of the small diameter hollow tube 6 away from the large diameter hollow bend 7, and a temperature sensing element 3 is provided at a position in the large diameter hollow bend 7 away from the small diameter hollow tube 6.

[0056] Specifically, based on the high-speed low-temperature gas-liquid two-phase flow test bench built, the actual icing duct working environment was simulated, and the above-mentioned temperature probe test piece was placed in a high-speed low-temperature two-phase flow to conduct experiments to verify the actual use effect of the temperature probe. The lower the droplet speed, the easier it is to change its motion trajectory, and the greater the probability of entering the flow channel. Therefore, the lowest flow velocity (50m / s) and LWC of 3 g / m 3 , the shooting was carried out under the condition of suction flow rate of 10.1687slpm.

[0057] like Fig.10 As shown, the high-speed low-temperature gas-liquid two-phase flow test bench is mainly composed of three systems. The first is the high-speed low-temperature airflow supply system, which uses a centrifugal fan as the air source to provide sufficient air. Since the airflow generated by the centrifugal fan is chaotic and has extremely high turbulence, a rectifying section is added to the air duct to improve the uniformity of the incoming flow. The rectifying section adopts the form of a rectifying grid plus a honeycomb. Then the airflow passes through the rectifying section to complete the rectification, and then mixes with the liquid nitrogen spray generated by the liquid nitrogen spray system for heat exchange to form a low-temperature airflow. The droplet generation system is placed behind the high-speed low-temperature airflow supply system, and a large number of droplets are generated through a gas-liquid auxiliary atomization nozzle, which is mixed with the low-temperature airflow to form a low-temperature gas-liquid two-phase flow. The probe test system is located at the outlet 13 of the air duct, and is composed of a temperature measuring probe and supporting equipment. Among them, in order to simulate the high-speed low-temperature cloud environment in the icing wind tunnel, an efficient heat exchange system and an airflow speed increaser are designed for the test bench. In order to ensure that the airflow has enough heat exchange time, the initial flow rate of the airflow should not be too low, and the experimental working conditions require high wind speed. Therefore, the air duct is designed to be contracted, with the maximum cross-sectional size of the air duct being 600×600 mm and the outlet cross-sectional size being 100×100 mm. The design of the contraction section of the air duct refers to the above-mentioned icing wind tunnel, and the contraction angle is set to 7°, and the structural dimensions of the contraction section are determined accordingly.

[0058] Compared with heat pipe heat exchange cooling, liquid nitrogen spray cooling has a higher cooling efficiency. Liquid nitrogen evaporates very quickly and has a high latent heat, reaching 199.176 KJ / kg under standard working conditions. The degree of airflow cooling can be controlled by simply adjusting the flow rate of liquid nitrogen spray. A liquid nitrogen nozzle is set in the air duct. In order to make the liquid nitrogen spray evenly distributed in the flow channel, three liquid nitrogen nozzles are placed side by side. After the liquid nitrogen spray system, the air duct length is set to 4000 mm to give the liquid nitrogen sufficient time for evaporation and heat exchange. Then an atomizing nozzle is set to produce droplets, which are mixed with the low-temperature airflow to finally form a low-temperature gas-liquid two-phase flow.

[0059] like Fig.10 and Fig.12 As shown, the temperature probe is installed on the test bench, and the test bench consists of a test bench and a probe mounting bracket. The main body of the probe mounting bracket is a two-axis mobile platform, and the temperature probe is installed on the mobile platform mounting seat. At the same time, a control group probe 17 is installed above the bracket as a control experimental object for the temperature probe. The high-speed camera 15 and the light source 14 are arranged on both sides of the low-temperature gas-liquid two-phase flow 16. The bench is a double-layer platform, and the lower layer is placed with flow meters, power supplies, vacuum pumps and other temperature probe supporting equipment. In order to prevent the droplets in the two-phase flow from touching the lower electronic components and causing damage to the instrument, a water baffle is added on the windward side of the bench. The flow channel outlet 18 of the laboratory bench is set on the back of the temperature probe, and a temperature sensing element is used to monitor the temperature at the monitoring area 19; the endoscope 21 is installed in the large-diameter hollow curved pipe 7 of the temperature probe at one end away from the small-diameter hollow pipe 6, and a suction flow channel 20 is also arranged at this position.

[0060] In the selection of temperature sensing elements, the thermocouple type is mainly selected. At the same time, the thermocouple corresponding to the measurement range is selected according to the temperature range of the wind tunnel used. The above-mentioned gas phase temperature measuring probe used in high-speed low-temperature cloud and fog fields selects platinum resistor PT1000 as the temperature sensing element of the temperature measuring probe. Platinum resistors are resistant to vibration, have good stability, high accuracy, and are suitable for low-temperature environments. The temperature measurement range of platinum resistor PT1000 is -50℃-500℃, and the temperature measurement accuracy is ±0.15+0.002|T|. Platinum resistors mainly have two packaging structures: insulated and exposed. The temperature change rate of the temperature measuring probe when using two platinum resistors was tested. The response rate of the exposed type is about 4 times that of the insulated type. Therefore, the exposed platinum resistor is used as the temperature sensing element of the temperature measuring probe.

[0061] The specific steps for the temperature probe to conduct a simulated icing wind tunnel environment test are as follows: (1) Install the temperature probe, ensure that it is placed horizontally, connect the pipeline and supporting instruments, connect each sensor to the NI data acquisition device, and connect the NI data acquisition device to the computer to test whether the data acquisition system is operating normally.

[0062] (2) Turn on the vacuum pump 5 and adjust the vacuum pump suction flow rate, observe the display screen of the thermal gas mass flow meter, and wait for the reading to stabilize at the target value.

[0063] (3) Turn on the fan, adjust the fan speed through the inverter, and use a Pitot tube to measure the air flow velocity at the air duct outlet 13 to ensure that the air flow velocity reaches the target operating conditions.

[0064] (4) After the airflow stabilizes, turn on the computer and start data collection.

[0065] (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 outlet valve of the liquid nitrogen tank to generate liquid nitrogen spray and create a low-temperature gas-liquid two-phase flow environment.

[0066] (6) Observe the computer data acquisition panel, wait for the temperature measuring probe to re-establish temperature balance in the low-temperature airflow, and adjust the gas and liquid pressures of the gas-liquid assisted atomizing nozzle in advance.

[0067] (7) Open the gas-liquid assisted atomizing nozzle to form a high-speed low-temperature gas-liquid two-phase flow 16, and collect photos through the high-speed camera 15; observe the computer data acquisition panel, wait until the temperature probe re-establishes temperature equilibrium, stop data acquisition, turn off the vacuum pump 5, fan, liquid nitrogen spray and gas-liquid assisted atomizing nozzle, and end this round of testing.

[0068] Specifically, due to the frame limitation of the long-distance microscope lens of the high-speed camera 15, the entire temperature probe head structure cannot be placed in one frame, so the temperature probe head is divided into three areas for shooting separately to capture the trajectory of droplet movement. Before formal shooting, the camera needs to be calibrated. The calibration can be performed directly through the temperature probe in the frame. Since the structural dimensions of the temperature probe are known, the actual size of the frame can be directly converted. The temperature probe is manufactured by machining, and the maximum machining error is 0.018mm, so the measurement error of the captured image is within 0.3%.

[0069] like Fig.11As shown in the figure, if many droplets are not captured passing through the focal plane in areas one and two on the temperature probe, this indicates that there are fewer droplets distributed in this area, and the particle size is very small (below 15μm), and it is difficult for the lens to capture such extremely small droplets; a small number of in-focus droplets are captured, all of which move in a straight line in the horizontal direction, and no in-focus droplets whose movement trajectory is significantly disturbed are found, which indicates that in the areas on both sides of the temperature probe, the droplet movement is basically not affected by wall turbulence and suction, and the gas-liquid separation effect is good. Area three is the air inlet of the temperature probe, where it can be observed whether there are droplets that eventually enter the flow channel inside the temperature probe. At the air inlet of the temperature probe, if there are basically no droplets on the focal plane, droplets moving in a straight line will occasionally pass by near the air inlet of the temperature probe, indicating that the droplets in the two-phase incoming flow basically will not follow the air flow to the vicinity of the air inlet of the temperature probe, confirming that the turbulence structure of the temperature probe can achieve efficient gas-liquid separation for the two-phase incoming flow.

[0070] According to the analysis of the results of the above-mentioned temperature probe in the simulated icing wind tunnel environment test, in area one above the temperature probe, the movement of the droplets is basically not affected by the wall turbulence and suction, and the gas-liquid separation effect is good. In area two, the volume of the wall-attached droplets is large, and under the influence of the airflow, they will deform and break at the shrinkage point of the temperature probe. Some droplets are drawn into the airflow for follow-up movement, and some droplets adhere to the wall of the shrinkage section of the temperature probe and no longer move. In area three, after the gas-liquid separation of the temperature probe turbulence structure, there is basically no situation where the droplets follow the airflow into the flow channel. The wall-attached droplets move forward slowly under the action of the near-wall airflow, and finally break away from the wall at the air inlet of the temperature probe. Part of the liquid enters the air inlet of the temperature probe under the action of the suction of the temperature probe. At the same time, it can be found from the endoscope 21 that when liquid water enters the flow channel in the temperature probe in the form of wall-attached droplets, it has basically no effect on the temperature measurement results.

[0071] The present invention also provides an application of a gas phase temperature measuring probe for a high-speed low-temperature cloud fog field in the measurement of gas phase temperature in a high-speed low-temperature cloud fog field. The specific application verification has been described above.

[0072] Specifically, a temperature correction model of the temperature measuring probe is established in the application of the gas phase temperature measuring probe used in the high-speed low-temperature cloud fog field in the gas phase temperature measurement of the high-speed low-temperature cloud fog field, which is used to correct the gas phase temperature in the high-speed low-temperature cloud fog field measured by the gas phase temperature measuring probe used in the high-speed low-temperature cloud fog field.

[0073] In the application process of gas phase temperature measuring probe, there is generally a certain difference between the measurement result of the gas phase temperature measuring probe and the actual temperature of the airflow. In this application, a temperature correction model for the temperature measuring probe is established. The correction model includes a recovery coefficient fitting correlation and a correction coefficient. The specific process is: first, the recovery coefficient is obtained according to the recovery coefficient fitting correlation, and then the correction coefficient is obtained based on the recovery coefficient, and finally the temperature correction is performed according to the correction coefficient. After the measured temperature is corrected by the above-mentioned temperature correction model of the temperature probe, the temperature measurement error of the temperature measuring probe is controlled within 0.5°C, which meets the measurement accuracy requirements; at the same time, the effectiveness of the temperature correction model is verified.

[0074] Specifically, the recovery coefficient fitting correlation is shown in Formula 2, and the correction coefficient is shown in Formula 3: Formula 2 Where r is the restitution coefficient, Re h is the backward step Reynolds number, Re in is the Reynolds number of the gas phase temperature probe, T r The temperature measured by the gas phase temperature probe, ΔT r The difference between the temperature measured by the gas phase temperature measuring probe and the actual temperature of the gas flow; Formula 3 Among them, η is the correction coefficient, r is the recovery coefficient, C p is the constant pressure heat capacity of the air flow, V is the air flow velocity, T r Measure temperature for gas phase temperature probe.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the contents of the description and drawings of the present invention should also be included in the protection scope of the present invention.

Claims

1. A design method for a gas phase temperature measurement probe for a high-speed low-temperature cloud field, characterized in that: The following steps are involved: S1, based on the backward temperature measuring probe configuration, combined with the backward step two-phase flow theory in the backward temperature measuring probe configuration and the high-speed low-temperature cloud and fog field working conditions, the gas-liquid separation structure configuration of the backward temperature measuring probe is designed, and then the temperature measuring probe configuration is obtained, and a temperature sensing element detection position is set in the temperature measuring probe configuration; S2, performing two-phase flow simulation and suction flow simulation based on the temperature measuring probe configuration, realizing the simulation of gas-liquid flow characteristics caused by the suction flow of the temperature measuring probe configuration in the two-phase flow field, and analyzing the simulation results to obtain relevant data of droplets in the gas-liquid entering the temperature measuring probe configuration; S3, analyzing the relevant data of the droplets in the gas-liquid entering the temperature measuring probe configuration. If no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration, the suction flow design of the temperature measuring probe configuration is completed, and the next step is entered; Otherwise, repeat the suction flow simulation in step S2 until no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration; S4, performing a freezing numerical simulation on the temperature measuring probe configuration to obtain a reconstructed geometric model of the temperature measuring probe configuration after freezing, and performing a two-phase flow simulation based on the reconstructed geometric model of the temperature measuring probe configuration after freezing, and combining the suction flow rate of the designed temperature measuring probe configuration to achieve a simulation of the near-wall flow field changes and a simulation of the gas-liquid flow characteristics caused by the temperature measuring probe configuration after freezing in the two-phase flow field; S5, analyzing the simulation results of the change of the near-wall flow field caused by the temperature measuring probe configuration after freezing in the two-phase flow field and the simulation results of the gas-liquid flow characteristics, and obtaining relevant data of the droplets in the gas and liquid entering the temperature measuring probe configuration after freezing; S6, analyzing the data related to the droplets in the gas-liquid in the temperature measuring probe configuration after freezing, if no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration after freezing, the design is completed; Otherwise, steps S1-S5 are repeated until no droplets are detected at the temperature sensing element detection position in the temperature measuring probe configuration after freezing.

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

3. The design method of a gas phase temperature measurement probe for a high-speed low-temperature cloud field according to claim 1 is characterized in that: In S4, the numerical simulation of ice formation includes: calculating the airflow field based on the initial grid, and combining the calculation of droplet impacting the wall to obtain the ice formation calculation on the wall of the temperature measuring probe, realizing the boundary reconstruction of the ice model, and then obtaining the reconstructed geometric model of the temperature measuring probe configuration after ice formation; at the same time, determining whether the ice formation time in the ice formation numerical simulation process reaches the set use time of the temperature measuring probe configuration, if so, the simulation ends; otherwise, repeating the above-mentioned ice formation numerical simulation steps until the ice formation time in the ice formation numerical simulation process reaches the set use time of the temperature measuring probe configuration.

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

5. The design method of a gas phase temperature measurement probe for a high-speed low-temperature cloud field according to claim 4 is characterized in that: The LES-WALE turbulence model includes a large eddy model and a WALE model, wherein the large eddy model is used to perform modeling calculations on the large eddy in the separation vortex while modeling the small eddy in the separation vortex; The WALE model is used to optimize the simulation calculation of the near-wall flow field of the temperature measuring probe configuration after icing, and to correct the turbulent viscosity of the shear layer.

6. The method for designing a gas phase temperature measuring probe for a high-speed low-temperature cloud field according to claim 1, characterized in that: In S5, the simulation results of analyzing the changes in the near-wall flow field caused by the temperature measuring probe configuration after freezing in the two-phase flow field and the simulation results of the gas-liquid flow characteristics also include: obtaining and analyzing the flow field diagram of the temperature measuring probe configuration after freezing; if there is no disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, then continuing to analyze the relevant data of droplets in the gas and liquid entering the temperature measuring probe configuration after freezing, and judging whether droplets are monitored at the temperature sensing element detection position in the temperature measuring probe configuration after freezing; if there is a disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing, then repeating steps S1-S4 until there is no disturbed droplet distribution boundary line in the flow field diagram of the temperature measuring probe configuration after freezing.

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

8. A gas phase temperature measurement probe for high-speed low-temperature cloud and fog fields, characterized in that: The gas phase temperature measuring probe is designed by the design method for a high-speed low-temperature cloud field described in claims 1-7, wherein the gas phase temperature measuring probe comprises a hollow reducer bend, wherein the hollow reducer bend comprises a small diameter hollow tube and a large diameter hollow bend connected to one end thereof, 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 one end of the small diameter hollow tube away from the large diameter hollow bend to form a gas-liquid separation structure configuration, and a temperature sensing element is provided at a position of the large diameter hollow bend away from the small diameter hollow tube.

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

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

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