Infrared radiometer cyclone purge apparatus and design method

Abstract

The application discloses an infrared radiometer rotational flow purging device and a design method, and relates to the technical field of aero-engine monitoring. The device comprises a purging airflow sleeve, an air inlet, a rotational flow generating pipe, a first pipe opening, a second pipe opening, an optical sensing element, and rotational flow generating holes. The open end of the purging airflow sleeve is opposite to a monitoring heat source. The rotational flow generating pipe is coaxially arranged in the purging airflow sleeve. The rotational flow generating pipe has the first pipe opening facing the monitoring heat source and the second pipe opening extending out of the purging airflow sleeve. The middle section of the rotational flow generating pipe is used for arranging the optical sensing element for receiving infrared radiation. The pipe body of the rotational flow generating pipe is provided with a plurality of rotational flow generating holes between the position of the optical sensing element and the first pipe opening. The airflow is separated from the large-size pollution particles at the rotational flow generating holes and enters the rotational flow generating pipe to form rotational flow. The application separates and blocks the pollutants before the optical sensing element through the multiple airflows containing rotational flow, fundamentally reduces the lens fouling rate, and improves the measurement stability and reliability.

Description

Technical Field

[0001] This invention relates to the field of aero-engine monitoring technology. More specifically, this invention relates to an infrared radiometer vortex purging device and its design method. Background Technology

[0002] As a core device for monitoring the temperature of turbine blades in aero-engines, the radiation pyrometer, with its advantages of non-contact operation, fast response, and high measurement accuracy, can directly acquire temperature data of critical areas of the blade. This is crucial for preventing blade failure due to creep deformation and improving engine efficiency and fuel economy. To prevent contaminants such as sand, oxide particles, and carbon particles in the turbine flow field from depositing on the pyrometer lens surface, leading to signal attenuation and lower measured temperature values, current technologies generally employ a purging system to clean or isolate the surfaces of optical sensing elements such as lenses and mirrors.

[0003] In the aerospace field, a protective airflow is typically created by drawing air from the compressor to form an air curtain in front of the radiation pyrometer. However, due to the easy deposition of compressor impurities carried by the purge air itself, and the presence of submicron-sized and sticky particles that are difficult to remove, practical experience has shown that existing purge devices all have certain problems. Existing purge systems are mainly divided into three types: air scrubbing type, air curtain type, and stationary tube type. Air scrubbing type purge devices use high-speed airflow to directly scrub the lens surface, which is difficult to remove submicron-sized and sticky particles. Air curtain type purge devices avoid direct contact by forming an airflow barrier in front of the pyrometer lens, but they are prone to creating a dead zone between the pyrometer lens and the air curtain, leading to contaminant retention. Stationary tube type purge devices isolate the pyrometer lens by creating a stationary air zone, but they are prone to forming a backflow zone at the outlet of the stationary tube, which can guide contaminants towards the lens. These solutions still have significant shortcomings in terms of flow field structure optimization.

[0004] Current technical solutions and related research still have key gaps: First, existing research focuses primarily on quantitatively predicting pollutant deposition, without deeply analyzing the physical mechanisms of fouling such as particle rebound, turbulence, and impact adhesion. This lack of systematic understanding of the deposition paths of pollutants with different properties leads to designs relying on experience. Second, most designs neglect the erosion products and sand particles contained in the purge air drawn from the compressor in the aerospace field, failing to address the pollution problem of the purge air itself. Third, the suppression effect on the recirculation zone and dead zone in the flow field is limited, failing to effectively control the phenomenon of high-inertia particles rebounding to the lens after impacting the tube wall. These shortcomings result in persistently high fouling rates on pyrometer lenses, compromised measurement accuracy, and high maintenance costs, limiting their large-scale application in civil aero engines.

[0005] Therefore, addressing the three major technological gaps in existing technologies—namely, the unclear physical mechanism of lens fouling, the lack of treatment of purge air contamination, and the difficulty in suppressing dead zones and recirculation zones in the flow field—there is an urgent need for a novel infrared radiometer purging device based on a well-defined physical model, capable of simultaneously handling internal and external contamination sources and optimizing the flow field structure. A corresponding design method should also be proposed. By combining structural innovation with quantitative design methods, effective separation and blocking of contaminants of different particle sizes can be achieved, fundamentally reducing lens fouling rates and improving measurement stability and reliability to meet the long-cycle, high-precision temperature monitoring requirements of civil aviation engines. Summary of the Invention

[0006] One objective of this invention is to provide an infrared radiometer swirling purging device and design method, which achieves inertial pre-separation of contaminants by using multiple airflows containing swirling flow and utilizing swirling orifices with specific geometric structures. This effectively separates and blocks contaminants before the optical sensing element, fundamentally reducing lens fouling rate and improving measurement stability and reliability.

[0007] In order to achieve these and other objectives and advantages according to the invention, in a first aspect, the invention provides an infrared radiometer swirling purge device, comprising: a purge airflow sleeve having a closed end and an open end, the open end facing a monitored heat source, and the purge airflow sleeve being provided with an air inlet;

[0008] A vortex generating tube is coaxially disposed inside the purge airflow sleeve. The vortex generating tube has a first port facing the monitoring heat source and a second port extending out of the purge airflow sleeve. An annular airflow channel is formed between the outer wall of the vortex generating tube and the inner wall of the purge airflow sleeve. The airflow channel is connected to the air inlet.

[0009] The middle section of the vortex generating tube is used to set an optical sensing element that receives infrared radiation. The tube body of the vortex generating tube has several vortex generating holes that penetrate the tube wall between the optical sensing element setting position and the first tube opening. The central axis of the vortex generating hole forms an acute angle with the axis of the vortex generating tube and does not intersect with the axis of the vortex generating tube.

[0010] The high-speed airflow flowing through the airflow cavity splits into two paths when it reaches the vortex generating hole. The first airflow continues forward along the airflow cavity and is ejected from the open end of the purge airflow sleeve. The second airflow is tangentially introduced into the internal cavity of the vortex generating tube through the vortex generating hole, and achieves inertial separation of large-diameter pollutants by means of centrifugal force during tangential acceleration. Subsequently, a vortex is formed between the optical sensing element and the first pipe opening and ejected from the first pipe opening.

[0011] Preferably, the plurality of swirl generating holes are evenly distributed circumferentially along the swirl generating tube.

[0012] Preferably, the cross-sectional shape of the swirl generating hole is a parallelogram.

[0013] Preferably, the acute angle between the central axis of the swirl generating hole and the axis of the swirl generating tube is 60°~70°.

[0014] Preferably, the first port is located inside the purge airflow sleeve, and the inner diameter of the purge airflow sleeve in the cylindrical section between the open end and the first port gradually decreases in the direction toward the open end, forming a first reduced diameter section.

[0015] Preferably, in the section where the swirl generating hole is located, the cross-sectional area of ​​the airflow cavity gradually decreases along the airflow direction.

[0016] Preferably, the inner wall of the cyclone generator tube is coated with a polytetrafluoroethylene coating, the thickness of which is 25~50μm and the surface energy is less than 20mN / m.

[0017] Secondly, the present invention provides a design method for an infrared radiometer vortex purging device, comprising the following steps:

[0018] S1. Based on the structural information, installation position and monitoring heat source direction of the optical sensing element, determine the initial geometry of the purge airflow sleeve, vortex generator tube and vortex generator hole;

[0019] S2. Establish a corresponding three-dimensional fluid domain model in the fluid simulation software, perform fluid simulation calculations according to the design air intake conditions, and extract airflow field parameters from the calculation results. The airflow field parameters include the characteristic velocity of the airflow inside the airflow cavity, the tangential velocity component of the airflow at the swirling hole, and the terminal velocity of the airflow at the open end of the purge airflow sleeve.

[0020] S3. Evaluate and judge the initial geometric structure using a quantitative evaluation model. The evaluation and judgment include:

[0021] a) Establish a particle motion compliance assessment model based on the Stokes number, input the characteristic velocity of the airflow to calculate the Stokes value, and compare it with the preset threshold conditions for judgment;

[0022] b) Establish a cyclone separation efficiency evaluation model based on the critical separation diameter, input the tangential velocity component of the airflow to calculate the critical separation particle size, and compare it with the lower limit of the target pollutant particle size to make a judgment;

[0023] c) Establish an air curtain barrier effectiveness assessment model based on outlet dynamic pressure, input the airflow terminal velocity to calculate the outlet dynamic pressure value at the open end, and compare it with the static pressure of the engine compartment environment to make a judgment;

[0024] S4. If any evaluation judgment result in step S3 fails to meet the corresponding preset judgment condition, the initial geometric structure is readjusted based on the flow field analysis results, and steps S2 to S4 are repeated until the geometric structure after iterative adjustment meets all preset judgment conditions.

[0025] Preferably, the calculation formula for the particle motion compliance assessment model is as follows:

[0026] ;

[0027] in, St For the Stokes number, t p For particle relaxation time, u The characteristic velocity of the airflow within the airflow cavity. L The characteristic length of the airflow cavity. d p The particle size of the contaminant particles, r p For the density of polluting particles, m f For the gas dynamic viscosity, the preset threshold condition is: St≤1 .

[0028] Preferably, the calculation formula for the cyclone separation performance evaluation model is as follows: ;

[0029] in, d c For the critical separation particle size, r p For the density of polluting particles, m f The viscosity is the dynamic viscosity of the airflow. u ω The tangential velocity component of the airflow. r The characteristic radius of the vortex;

[0030] The preset condition is that the critical separation particle size is less than the lower limit of the target pollutant particle size.

[0031] The present invention has at least the following beneficial effects:

[0032] First, this application constructs an airflow path that runs parallel to the internal cavity of the airflow channel and the vortex generator tube by coaxially setting the purge airflow sleeve and the vortex generator tube. The vortex generator hole with a specific geometric configuration performs functional diversion of the purge airflow in front of the optical sensing element: the first airflow forms a high-speed and stable air curtain in front of the open end, effectively blocking external pollutants from the engine turbine chamber; the second airflow is tangentially introduced into the vortex generator tube through the vortex generator hole to form a strong vortex field, which actively captures and centrifugally removes the very few external particles that may penetrate and the particles carried by the bleed air itself. The overall anti-scaling effect is significantly better than that of a single airflow mode.

[0033] Secondly, this application designs the swirling orifice itself as a first-stage high-efficiency inertial particle separator. When the high-speed airflow passes through the swirling orifice, which is at an acute angle to the axis of the swirling tube and does not intersect, the airflow direction changes drastically, generating a strong centrifugal force field. Large-diameter pollutants with greater inertia cannot follow the airflow to turn and are thrown out at the entrance of the swirling orifice, thus being blocked outside the swirling tube and discharged from the system with the first airflow. This achieves the screening of large-diameter pollutants in the induced air and eliminates the risk of large-diameter pollutants hitting the optical sensing element from the source.

[0034] Third, the design methodology accompanying this application transforms the abstract anti-fouling requirements into quantifiable physical verification targets. By establishing a closed-loop process of "design-simulation-verification-optimization," the separation performance, flow field motion capability, and air curtain blocking effect of the swirling orifice are quantitatively evaluated and iterated. This method realizes the transformation from empirical design to forward design based on physical models, significantly improving the scientific rigor and reliability of the design and ensuring that the device can meet the long-term operational requirements of various types of aero-engines under harsh operating conditions.

[0035] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of an overall technical solution of the present invention;

[0037] Figure 2 This is a side cross-sectional view of the structure in one technical solution of the present invention;

[0038] Figure 3 This is a partially enlarged schematic diagram of the swirl generating tube in one technical solution of the present invention, wherein (a) is a side cross-sectional view; and (b) is a front cross-sectional view of the swirl generating hole.

[0039] Figure 4 This is a schematic diagram of a swirl generator hole according to one technical solution of the present invention;

[0040] Figure 5 This is a schematic diagram of the flow field of a three-dimensional fluid domain model in one technical solution of the present invention;

[0041] Figure 6 This is a partially enlarged view of the flow field schematic diagram of a three-dimensional fluid domain model in one of the technical solutions of the present invention;

[0042] Figure 7 This is a schematic diagram of particle deposition in one technical solution of the present invention. Figure one (a) is a schematic diagram of particle deposition in Example 1, (b) is a schematic diagram of particle deposition in Example 2, (c) is a schematic diagram of particle deposition in Example 3, and (d) is a schematic diagram of particle deposition in Example 4.

[0043] Reference numerals: 1-Purge airflow sleeve, 10-Inlet, 100-Base, 11-First diameter reduction section, 12-Second diameter reduction section, 2-Swirl generator tube, 21-First port, 20-Second port, 3-Airflow cavity, 4-Optical sensing element, 41-Rod, 5-Swirl generator hole, 51-Inner cut, 52-Outer cut. Detailed Implementation

[0044] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can implement it based on the description.

[0045] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0046] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the structures and components described are commercially available. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to fixed connection or setting, detachable connection or setting, or integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0047] like Figure 1~4 As shown, the present invention provides an infrared radiometer vortex purging device, comprising:

[0048] A purge airflow sleeve 1 has a closed end and an open end, with the open end facing the monitoring heat source. The purge airflow sleeve 1 is provided with an air inlet 10. A vortex generating tube 2 is coaxially disposed inside the purge airflow sleeve 1. The vortex generating tube 2 has a first port 21 facing the monitoring heat source and a second port 20 extending out of the purge airflow sleeve 1. An annular airflow channel 3 is formed between the outer wall of the vortex generating tube 2 and the inner wall of the purge airflow sleeve 1. The airflow channel 3 is connected to the air inlet 10. The middle section of the vortex generating tube 2 is used to house an optical sensing element 4 for receiving infrared radiation. Several [unclear] are arranged in the tube body of the vortex generating tube 2 between the optical sensing element 4 and the first port 21. A swirl generating hole 5 penetrates the wall of the swirl generating tube 2. The central axis of the swirl generating hole 5 forms an acute angle with the axis of the swirl generating tube 2 and does not intersect with the axis of the swirl generating tube 2. The high-speed airflow flowing through the airflow cavity 3 splits into two paths when it reaches the swirl generating hole 5. The first path of airflow continues forward along the airflow cavity 3 and is ejected from the open end of the purge airflow sleeve 1. The second path of airflow is tangentially introduced into the internal cavity of the swirl generating tube 2 through the swirl generating hole 5. During the tangential acceleration process, it achieves inertial separation of large-diameter pollutants by means of centrifugal force. Subsequently, after forming a swirl between the optical sensing element 4 and the first nozzle, it is ejected from the first nozzle.

[0049] In this technical solution, the optical sensing element 4 is typically an optical window element such as a lens or a reflector, whose function is to directly receive infrared radiation signals from the turbine blades of an aero-engine. The optical sensing element 4 is coaxially and fixedly mounted in the internal cavity of the vortex generator tube 2 via a slender rod 41. The rod 41 serves to precisely position the optical sensing element 4 at a preset axial position in the vortex generator tube 2, ensure that its optical end face maintains a specific relative positional relationship with the first opening 21 of the vortex generator tube 2, and allow the optical fiber connected to the optical sensing element 4 to be set with the rod 41 as the base. The rod 41 extends from the second opening 20 and connects to the corresponding external equipment.

[0050] In the actual engine mounting configuration, the purge airflow sleeve 1 has its open end facing the inside of the engine's hot end, directly monitoring heat sources such as turbine blades, while the closed end with the air inlet 10 is located outside the engine casing or mounting base, facilitating connection to the air supply pipeline and maintenance. In a specific embodiment, the purge airflow sleeve 1 and the swirl generator 2 are integrated through a shared base 100. The base 100 is an annular component with a pre-formed chamber communicating with the airflow channel 3 and the air inlet 10. The outer annular wall of the base 100 extends axially toward the inside of the engine, directly forming the cylinder of the purge airflow sleeve 1, while the inner annular wall of the base 100 extends coaxially, forming the swirl generator 2. The air inlet 10 penetrates the side wall or end face of the base 100 and communicates with the airflow channel 3.

[0051] In terms of manufacturing, the main body of the purge airflow sleeve 1 and the vortex generating tube 2 can be made of high-performance nickel-based high-temperature alloys (such as Inconel 718 or Haynes 230) through precision machining or investment casting. For complex parts, a segmented machining and assembly connection process can be adopted. Specifically, a portion of the purge airflow sleeve 1 from the open end to the rear, and a section of the vortex generating tube 2 including the first port 21 and the vortex generating hole 5, can be machined as independent sub-components. On this sub-component, the vortex generating hole 5 with a specific angle and shape is precisely manufactured through milling, electrical discharge machining, or laser machining. Subsequently, the machined sub-component is assembled and docked with the main body extending from the base 100, and the docking point is connected by electron beam welding or laser welding.

[0052] Each swirl generating hole 5 has an inner cutout 51 located on the inner wall of the swirl generating tube 2, facing the internal cavity, and an outer cutout 52 located on the outer wall of the swirl generating tube 2, connecting with the airflow channel 3. When the high-speed airflow from the inlet 10 reaches the location of the swirl generating hole 5 through the annular airflow channel 3, the airflow undergoes path separation at the outer cutout 52. The first path of airflow bypasses this structure and continues to flow along the airflow channel 3 toward the open end. The second path of airflow enters the interior of the swirl generating hole through the outer cutout 52. Since the central axis of each swirl generating hole 5 is set to form an acute angle with the axis of the swirl generating tube 2, and the central axis of the swirl generating hole 5 does not intersect with the axis of the swirl generating tube 2. This geometric constraint determines the direction of the second airflow within the vortex generating orifice 5. The high-speed airflow passing through the vortex generating orifice 5 is forced to move along an acute angle in space that is neither radial nor axial. This guiding process decomposes the momentum of the high-speed airflow into two components: a tangential component perpendicular to the axis of the vortex generating tube 2, and an axial component parallel to the vortex generating tube 2. When the second airflow finally flows out from the inner cutout 51 located on the inner wall of the vortex generating tube 2, its tangential momentum component becomes the driving force for the airflow to rotate around the tube axis of the vortex generating tube 2, forming a vortex field. Its axial momentum component ensures that the airflow can move along the direction of the vortex generating tube 2 toward the first opening 21. The several vortex generating orifices 5 are uniformly distributed circumferentially along the vortex generating tube, ensuring that the tangential momentum is injected symmetrically and uniformly, thereby generating an axisymmetric and highly stable forced vortex field. This avoids distortion or oscillation caused by asymmetrical air intake.

[0053] While generating swirl, the swirl-generating orifice 5 itself also functions to separate inertial particles. Its separation mechanism is based on the drastic change in direction of the high-speed airflow at the inlet of the swirl-generating orifice 5 and the resulting centrifugal force. When a high-speed airflow carrying pollutants of different particle sizes arrives at the outer incision 52 of the swirl-generating orifice 5 from the annular airflow cavity 3, a portion of the airflow is forced to abruptly change from its original axial flow to a spatial direction forming an acute angle with the main axis of the purge airflow sleeve 1, entering the swirl-generating orifice 5. This abrupt change in flow exerts a relatively large centrifugal force on the solid particles entrained in the high-speed airflow. For pollutant particles with larger diameters and masses, their relaxation time is longer and their inertia is greater. At the instant the airflow suddenly changes direction, these large particles tend to maintain their original motion trend and cannot quickly adjust their trajectory to adapt to the new flow direction. Thus, at the outer incision 52, large-diameter contaminants are subjected to strong centrifugal force and are directly ejected from the "turning path" of the second airflow. They are then carried forward by the mainstream first airflow along the annular airflow cavity 3 and finally discharged from the open end of the purge airflow sleeve 1. This ensures that large-diameter contaminants that could scratch the lens or rebound violently are stripped away and are not allowed to enter the vortex generator tube 2 where the optical sensing element 4 is located. This eliminates the risk of large-diameter contaminants directly impacting and abrading the optical window or rebounding on the inner wall, causing secondary contamination, and improves the long-term operational reliability and maintenance cycle of the entire measurement system.

[0054] In one technical solution, the cross-sectional shape of the swirl-generating hole 5 is a parallelogram. The parallelogram cross-section provides two parallel long sides for the inner wall of the swirl-generating hole 5, which act as efficient guiding surfaces when airflow passes through. When airflow flows in from the outer incision 52, the parallelogram guiding surface can exert a continuous, smooth, and consistent guiding effect, guiding the airflow to flow strictly in the preset direction of the central axis of the swirl-generating hole 5. Compared with common circular or rectangular cross-sections, the parallelogram can more effectively suppress flow separation, boundary layer delamination, or the generation of disordered secondary eddies that may occur in the airflow within the swirl-generating hole 5, thereby ensuring that the airflow, especially the critical tangential momentum component, is transferred to the inner incision 51 with the highest efficiency and lowest turbulence. The two parallel long sides of the parallelogram form a better guiding surface, which can guide the airflow smoothly and centrally to turn along the preset direction, minimizing turbulence and flow separation. This ensures that the centrifugal force experienced by large-diameter pollutants at the outer incision 52 is clearly directional and concentrated, allowing them to be ejected more efficiently and thoroughly, preventing them from entering the vortex generation hole 5.

[0055] In one technical solution, the acute angle between the central axis of the swirl generating hole 5 and the axis of the swirl generating tube 2 is 60°~70°. When the angle is within this range, the momentum distribution obtained by the airflow when passing through the swirl generating hole 5 reaches a better balance. Its moderate axial component ensures that the airflow has the necessary forward propulsion speed, ensuring the stability of the flow and the final discharge of pollutant particles entering the swirl generating tube 2. At the same time, its dominant tangential component is sufficient to form a strong swirling field in the swirl generating tube 2, achieving the best balance between separation efficiency, flow resistance and system reliability.

[0056] This technical solution innovatively splits the airflow from a single source in front of the optical sensing element 4 by using a coaxially arranged purge airflow sleeve 1 and swirl generator tube 2, and utilizing the annular airflow cavity 3 and specific swirl generator hole 5 between them. The first airflow ultimately forms a high-speed external air curtain, effectively blocking external pollutants in the engine turbine flow field. The second airflow is precisely guided. The swirl generator hole 5, as a swirl generator structure, is also used to separate large-diameter pollutants. The second airflow forms a strong swirling field in the swirl generator tube 2, further preventing the backflow of particles from the first pipe opening 21. This technical solution solves the common technical defects of traditional purging schemes, such as the existence of dead zones or backflow zones in the flow field and the inability to handle the self-contamination of the purge air. This significantly reduces the risk of scaling on optical elements, improves temperature measurement accuracy and system maintenance cycle, and is more suitable for the application requirements of long life and high reliability of civil aviation engines.

[0057] In another technical solution, the first port 21 is located inside the purge airflow sleeve 1. The inner diameter of the cylindrical section of the purge airflow sleeve 1 between the open end and the first port 21 gradually decreases in the direction towards the open end, forming a first reduced-diameter section 11. The open end of the purge airflow sleeve 1 constitutes a typical converging flow channel. When incompressible airflow flows through this channel with a gradually decreasing cross-sectional area, its velocity will increase significantly with the decrease in cross-sectional area, and the dynamic pressure of the airflow will increase accordingly, so that the first airflow delivered from the airflow cavity 3 is purposefully accelerated before reaching the open end outlet.

[0058] The streamlined, tapering profile of the first narrowing section 11 also optimizes the internal flow field. The first airflow exiting the airflow cavity 3 and the second airflow exiting the first port 21, which exhibits a swirling tendency, converge. The tapering flow channel of the first narrowing section 11 acts as both a constraint and a guide for the two airflows, forcing them to merge along a clear and concentrated direction. This results in a composite air curtain at the open outlet, characterized by higher speed, a more compact structure, and greater stability. This high-speed, stable external jet, completed within the narrowing flow field, effectively suppresses the inherent backflow zone near the outlet in traditional designs, fundamentally eliminating the path for contaminants to be transported to the optical components.

[0059] In another technical solution, in the section where the swirl generating hole 5 is located, the cross-sectional area of ​​the airflow cavity 3 gradually decreases along the airflow direction. According to Bernoulli's principle, when airflow passes through a gradually narrowing pipe, its velocity will increase while its static pressure will decrease. A second narrowing section 12 can be formed at the corresponding position of the swirl generating hole 5 by purging the airflow sleeve 1, thereby reducing the cross-sectional area of ​​the airflow cavity 3 and improving the "suction" effect of the swirl generating hole 5 on the total airflow. This guides a larger proportion of the airflow to choose to enter the swirl generating pipe 2 through the swirl generating hole 5, becoming the second airflow to participate in the generation of swirl.

[0060] In another technical solution, the inner wall of the vortex generating tube 2 is coated with a polytetrafluoroethylene (PTFE) coating. The PTFE coating has a thickness of 25-50 μm and a surface energy of less than 20 mN / m. PTFE, as a high-performance low-surface-energy material, has a surface energy significantly lower than that of metals or other common engineering materials. When contaminating particles collide with the tube wall under centrifugal force, the interaction forces between the particles and the wall mainly include van der Waals forces and electrostatic forces. These two forces are the main mechanisms leading to particle adhesion. The extremely low surface energy of the PTFE coating fundamentally weakens the magnitude of van der Waals forces. Simultaneously, this material possesses excellent dielectric properties and charge dissipation characteristics, which help reduce the accumulation of static charge on the surface, thereby reducing electrostatic adsorption. The quantitative indicator of a surface energy of less than 20 mN / m ensures that the coating achieves a superhydrophobic and low-adhesion physical state. Controlling the thickness within the range of 25-50 μm aims to ensure sufficient continuity and mechanical durability of the coating to withstand the scouring of high-speed particles and the shearing effect of airflow, while avoiding the risk of thermal stress or peeling due to excessive thickness. Commonly used coating methods include air spraying or electrostatic spraying, which uniformly atomize and deposit a special suspension or dispersion containing polytetrafluoroethylene particles onto the inner wall surface of the swirl generator tube 2.

[0061] An infrared radiometer cyclone purging device is provided for temperature monitoring of turbine blades in a GE90 civil aircraft engine. The dimensions and materials of the core components of the device are as follows:

[0062] The optical sensing element 4 of the radiation pyrometer probe is a quartz lens with a diameter of 1.5 mm and a length of 3 mm, which is connected to the downstream spectrometer via a quartz optical fiber with a diameter of 0.8 mm and a length of 200 mm. The overall length of the purge gas sleeve 1 is 156.5 mm, the inner diameter at the middle is 16 mm, the inner diameter at the open end is designed to be 7 mm, and the wall thickness of the purge gas sleeve 1 is 1.5 mm. The vortex generator tube 2 is coaxially mounted, and its inner diameter at the location where the optical sensing element 4 is set is 8 mm, the inner diameter at the first opening is 6 mm, and the tube wall thickness is 2 mm. The swirl generating holes 5 are evenly distributed circumferentially, with a total of 6 swirl generating holes 5. Each swirl generating hole 5 is a parallelogram with a side length of 2 mm and a height of 2 mm. The central axis of the swirl generating hole 5 forms a 65° angle with the axis of the swirl generating tube 2. The inner wall of the swirl generating tube 2 is coated with a polytetrafluoroethylene coating with a thickness of 25 μm. Its surface energy is measured to be 18 mN / m. The purge airflow is taken from the high-pressure compressor of the engine, with an initial bleed air pressure of 800 kPa and a temperature of 600 K.

[0063] To investigate the impact of key operating parameters on purging performance, this section sets up four comparative examples, with the variables being the vertical air intake velocity of the airflow channel 3 and the axial distance between the inner cut 51 of the swirl generator hole 5 and the lens surface of the optical sensing element 4.

[0064] Example 1: The air intake speed is 0.5 m / s, and the distance between the inner notch 51 and the lens axis is 2 mm.

[0065] Example 2: The air intake speed is 0.5 m / s, and the distance between the inner notch 51 and the lens axis is 4 mm.

[0066] Example 3: The air intake speed is 1.5 m / s, and the distance between the inner notch 51 and the lens axis is 2 mm.

[0067] Example 4: The air intake speed is 1.5 m / s, and the distance between the inner notch 51 and the lens axis is 4 mm.

[0068] To perform quantitative analysis and comparison of the four embodiments described above, an accurate three-dimensional fluid-particle multiphysics coupled simulation model was established using COMSOL Multiphysics finite element analysis software. In the simulation, the steady-state flow field was first solved to obtain the internal velocity and pressure field distributions of each embodiment under the corresponding inlet conditions.

[0069] like Figure 6As shown, taking the simulation results of Example 1 as an example, the airflow is accelerated to over 11 m / s at the open end, establishing a stable, outward-pointing positive pressure differential region outside the open end. Under typical engine compartment ambient air density, an airflow velocity of 11 m / s can form a local positive pressure zone with significant amplitude around the open end. The analysis of the other three examples also confirms that, within the given parameter range, the structure of the present invention can form a high-speed air curtain with sufficient momentum and a stable positive pressure differential at the open end, thereby ensuring the primary physical isolation function.

[0070] Based on this, a transient particle tracking module was activated to release representative contaminant particles into the flow field to evaluate the purging effect. The particles were set as silica particles with a density of 2650 kg / m³ and a particle size of 25 μm, totaling 100 particles, initially randomly distributed in the airflow cavity 3 before the swirl generation hole 5. The particle force model considered inertial force, fluid drag force, and turbulent diffusion effect, and set the interaction conditions between the particles and the wall, including rebound and adhesion models, where the adhesion probability is related to the wall material.

[0071] By post-processing and data extraction of the simulation results of the four embodiments, the particle trajectory, final position, and quantity statistics for each embodiment were obtained. The simulation results are as follows: Figure 7 As shown, and through comprehensive analysis of four sets of data, it was concluded that no particles were observed on the lens surface, which is the optical sensing element 4, in all four embodiments, i.e., the deposition rate on the lens surface was 0%. This proves that the core structure of the present invention can effectively protect the optical window from contamination under different air intake conditions and key dimensions.

[0072] In another technical solution, the design method of the infrared radiometer cyclone purging device includes the following steps:

[0073] S1. Based on the structural information, installation position and monitoring heat source direction of the optical sensing element, determine the initial geometric structure of the purge airflow sleeve 1, the vortex generating tube 2 and the vortex generating hole 5.

[0074] Specifically, the dimensions of the vortex generating tube 2 are first determined based on the physical dimensions, shape, and fixed position of the optical sensing element 4 of the infrared radiometer probe on the rod 41. The section of the vortex generating tube 2 used to house the optical sensing element 4 must have an inner diameter slightly larger than the maximum outer diameter of the optical sensing element 4. The total length of the vortex generating tube 2 is determined by the distance from the mounting point of the optical sensing element 4 to the preset mounting base in the engine compartment, and the depth to which it needs to be inserted into the engine flow channel for monitoring.

[0075] Next, based on the selected engine model and its internal structure, the overall shape and dimensions of the purge airflow sleeve 1 are determined. The outer diameter and length of the purge airflow sleeve 1 must accommodate the reserved installation space within the engine compartment, and the shape and dimensions of its closed end must match the standard mounting interface or custom base provided on the engine casing. The position and diameter of the air inlet 10 need to be initially set according to the available interface positions and directions of the engine bleed air pipeline to ensure smooth access to the air source. Based on the preliminary dimensions of the swirl generator tube 2 and the installation boundary of the purge airflow sleeve 1, the initial radial clearance of the airflow cavity 3 between them is determined.

[0076] Finally, based on the preliminary estimated airflow rate and the desired swirl intensity to be formed within the swirl generating tube 2, the initial parameters of the swirl generating orifice 5 are determined. This includes the axial placement of the swirl generating tube 2, the initial number of orifices in the circumference, the initial shape, and the initial angle between the axis of the swirl generating orifice 5 and the axis of the swirl generating tube 2.

[0077] S2. Establish a corresponding three-dimensional fluid domain model in the fluid simulation software, perform fluid simulation calculations according to the design air intake conditions, and extract airflow field parameters from the calculation results. The airflow field parameters include the characteristic velocity of the airflow inside the airflow cavity 3, the tangential velocity component of the airflow at the swirl generator hole 5, and the terminal velocity of the airflow at the open end of the purge airflow sleeve 1.

[0078] Specifically, general-purpose computational fluid dynamics software, such as ANSYS Fluent, STAR-CCM+, or COMSOL Multiphysics, can be used for simulation analysis. The modeling process is based on the initial geometry determined in step S1, creating three-dimensional solid models of key components such as the purge airflow sleeve 1, swirl generator tube 2, swirl generator orifice 5, and inlet 10 in the software. The design of the inlet conditions defines the fluid boundary conditions for the simulation input, including but not limited to the total pressure and temperature of the airflow at inlet 10, the inlet velocity or mass flow rate of the airflow, and the working fluid properties.

[0079] After the calculation is completed, the required airflow field parameters are extracted from the post-processing results. A representative section is selected in the airflow cavity 3, and the average velocity or maximum velocity of the section is extracted as the characteristic velocity of the airflow. In the central region or outlet position of the swirl generator hole 5, the projection component of the airflow velocity vector on the plane perpendicular to the axis of the swirl generator tube 2 is extracted as the tangential velocity component of the airflow. At the open end outlet section of the purge airflow sleeve 1, the average velocity or central axis velocity of the section is extracted as the terminal velocity of the airflow.

[0080] S3. Evaluate and judge the initial geometric structure using a quantitative evaluation model. The evaluation and judgment include:

[0081] a) Establish a particle motion compliance assessment model based on the Stokes number, calculate the Stokes value by inputting the characteristic velocity of the airflow, and compare it with a preset threshold condition. The calculation formula of the particle motion compliance assessment model is as follows:

[0082] ;

[0083] in, St For the Stokes number, t p For particle relaxation time, u The characteristic velocity of the airflow within the airflow cavity. L The characteristic length of the airflow cavity. d p The particle size of the contaminant particles, r p For the density of polluting particles, m f The gas dynamic viscosity is the preset judgment condition. St≤1 .

[0084] For example, taking Embodiment 1 as a calculation example, based on the simulation results, the airflow velocity at the swirl generation hole 5 in the airflow cavity 3 is extracted as the airflow characteristic velocity. u It is 4.67 m / s , characteristic length L The overall length of the purging airflow sleeve 1 is 0.1565. m The target contaminant particles were selected as silica particles, with a density of [missing information]. r p 2650 kg / m³ Particle size d p 50 μm Aerodynamic viscosity m f Based on the bleed air temperature (600K), it is taken as 2.8×10. -5 kg / (m·s) The calculated Stokes number St ≈0.392, which satisfies the condition. St≤1 The preset judgment conditions are as follows. Therefore, in the airflow cavity 3 designed in Example 1, the response time of the simulated oxide particles with large inertia is sufficient to keep up with the airflow. The target contaminant particles can move smoothly with the airflow without significantly deviating from the streamline due to excessive inertia, thus avoiding violent inertial impact deposition on both sides of the airflow cavity 3.

[0085] b) Establish a cyclone separation efficiency evaluation model based on the critical separation diameter, input the tangential velocity component of the airflow to calculate the critical separation particle size, and compare it with the lower limit of the target pollutant particle size; the calculation formula of the cyclone separation efficiency evaluation model is as follows: ;

[0086] in, d c For the critical separation particle size, r p For the density of polluting particles, m f The viscosity is the dynamic viscosity of the airflow. u ω The tangential velocity component of the airflow. r The characteristic radius of the swirl is used; the preset condition is that the critical separation particle size is less than the lower limit of the target pollutant particle size.

[0087] The cyclone separation performance evaluation model is based on the calculation formula of the centrifugal force on the contaminant particles. Formula for calculating the viscosity force of airflow Established, among which F c The centrifugal force experienced by the contaminating particles F u For airflow viscosity force, m p For the mass of contaminating particles, d p For the particle size of the contaminating particles, when the critical separation particle size is... d c If the particle size is smaller than the lower limit of the target pollutant particle size, it can be considered that the target pollutant particles can be effectively separated at the swirl generation hole 5.

[0088] The target contaminant particle size limit refers to the smallest contaminant particle diameter that the purging device must be able to effectively separate and block during the design phase. It is a key design indicator determined based on measured data of bleed air contaminants from a specific engine, protection requirements of optical sensing elements, and engineering experience; for example, it might be set to 5. μm Or 10 μm The design goal is to ensure that all contaminant particles larger than this lower limit are effectively intercepted outside the swirl generator tube 2.

[0089] For example, the lower limit of the target pollutant particle size is set to 5. μm Taking Example 1 as an example, based on the simulation results of Example 1, the tangential velocity component of the airflow is extracted from the flow field data. u ω It is 9.2 m / s vortex characteristic radius r The narrowest section of the vortex generator tube 2 is taken as 0.008.m The calculated critical separation particle size d c ≈ 4.24 μm This indicates that the swirl-generating aperture 5, designed according to the parameters of Example 1, can theoretically effectively intercept particles with a diameter greater than or equal to 4.24 mm. μm Pollution particles, for particles with a diameter of 5 μm The above-mentioned pollutant particles achieved the preset separation effect.

[0090] c) Establish an air curtain barrier effectiveness assessment model based on outlet dynamic pressure. Input the airflow terminal velocity to calculate the outlet dynamic pressure value at the open end, and compare it with the static pressure of the engine compartment environment. The physical significance of the air curtain barrier effectiveness assessment model is to verify whether the first airflow ejected from the open end of the purge airflow sleeve 1 can form an air curtain with sufficient momentum to resist the infiltration and interference of the flow field within the engine compartment. The judgment logic is that only when the outlet dynamic pressure value at the open end is greater than the static pressure of the engine compartment environment at its location can a stable local positive pressure zone be established, thereby effectively blocking external pollutants from intruding in the reverse direction with the ambient airflow.

[0091] The typical ambient static pressure near the open end of the engine nacelle is determined by the engine type and specific flight conditions (such as takeoff and cruise), and is a known parameter. The outlet dynamic pressure value is... P d The calculation formula is: ,in r f For airflow density, u out This represents the velocity at the airflow terminal.

[0092] For example, the simulation results of Embodiment 1 are used for verification. According to the simulation calculation results, the airflow terminal velocity at the open end is 11.3. m / s airflow density r f The value was determined to be 1.2 based on the air intake conditions. kg / m³ According to the formula, the outlet dynamic pressure value can be determined. P d It is 86.4 Yes By consulting the relevant engine design specifications, under the target operating conditions, the static pressure of the engine compartment environment at the open end location is 60. Yes This demonstrates that, under a given engine environmental pressure, the air curtain generated in Example 1 can establish a stable positive pressure zone outside the open end, thereby possessing the ability to resist environmental flow field infiltration, suppress backflow, and form an effective barrier.

[0093] S4. If any evaluation result in step S3 fails to meet the corresponding preset judgment condition, the initial geometry is readjusted based on the flow field analysis results. Steps S2 to S4 are repeated until the iteratively adjusted geometry meets all preset judgment conditions. Specifically, if the Stokes number evaluation fails, it indicates that the following behavior of pollutant particles in the airflow cavity 3 is poor. It is usually necessary to adjust the characteristic length of the airflow cavity 3 or modify the structure to improve the characteristic airflow velocity, such as optimizing the cross-section of the airflow cavity 3. If the critical separation particle size is not smaller than the lower limit of the target pollutant particle size, it indicates that the centrifugal separation capability at the swirling orifice 5 is insufficient. It is necessary to focus on adjusting the geometric parameters of the swirling orifice 5, such as increasing the orifice inclination, increasing the number, or optimizing its cross-sectional shape to enhance the tangential velocity component of the airflow. If the outlet dynamic pressure fails to exceed the static pressure of the engine compartment environment, it indicates that the strength of the external air curtain barrier is insufficient. It is necessary to improve the airflow terminal velocity by adjusting the design of the reduced diameter section before the open end of the purge airflow sleeve 1, or to re-evaluate the intake conditions. After each structural adjustment, it is necessary to return to step S2, update the three-dimensional fluid domain model, and re-perform simulation calculations and evaluations. This process is repeated until all evaluation indicators meet the requirements, thereby obtaining the final geometric structure that meets the performance requirements.

[0094] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. An infrared radiometer cyclone purging device, characterized in that, include: A purge airflow sleeve has a closed end and an open end, the open end being directly facing the monitoring heat source, and the purge airflow sleeve is provided with an air inlet. A vortex generating tube is coaxially disposed inside the purge airflow sleeve. The vortex generating tube has a first port facing the monitoring heat source and a second port extending out of the purge airflow sleeve. An annular airflow channel is formed between the outer wall of the vortex generating tube and the inner wall of the purge airflow sleeve. The airflow channel is connected to the air inlet. The middle section of the vortex generating tube is used to house an optical sensing element that receives infrared radiation. The tube body of the vortex generating tube has a plurality of vortex generating holes penetrating the tube wall between the optical sensing element and the first tube opening. The central axis of the vortex generating hole forms an acute angle with the axis of the vortex generating tube and does not intersect the axis of the vortex generating tube. The plurality of vortex generating holes are evenly distributed circumferentially along the vortex generating tube. The first tube opening is located inside the purge airflow sleeve. The inner diameter of the purge airflow sleeve in the cylindrical section between the open end and the first tube opening gradually decreases in the direction toward the open end, forming a first diameter-reducing section. The high-speed airflow flowing through the airflow cavity splits into two paths when it reaches the vortex generating hole. The first airflow continues forward along the airflow cavity and is ejected from the open end of the purge airflow sleeve. The second airflow is tangentially introduced into the internal cavity of the vortex generating tube through the vortex generating hole, and achieves inertial separation of large-diameter pollutants by means of centrifugal force during tangential acceleration. Subsequently, a vortex is formed between the optical sensing element and the first pipe opening and ejected from the first pipe opening.

2. The infrared radiometer vortex purging device as described in claim 1, characterized in that, The cross-sectional shape of the swirl generating hole is a parallelogram.

3. The infrared radiometer vortex purging device as described in claim 1, characterized in that, The acute angle between the central axis of the swirling orifice and the axis of the swirling tube is 60°~70°.

4. The infrared radiometer vortex purging device as described in claim 1, characterized in that, In the section where the swirl generation hole is located, the cross-sectional area of ​​the airflow cavity gradually decreases along the airflow direction.

5. The infrared radiometer vortex purging device as described in claim 1, characterized in that, The inner wall of the cyclone generator tube is coated with a polytetrafluoroethylene coating, the thickness of which is 25~50μm and the surface energy is less than 20mN / m.

6. A design method for an infrared radiometer vortex purging device as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Based on the structural information, installation position and monitoring heat source direction of the optical sensing element, determine the initial geometry of the purge airflow sleeve, vortex generator tube and vortex generator hole; S2. Establish a corresponding three-dimensional fluid domain model in the fluid simulation software, perform fluid simulation calculations according to the design air intake conditions, and extract airflow field parameters from the calculation results. The airflow field parameters include the characteristic velocity of the airflow inside the airflow cavity, the tangential velocity component of the airflow at the swirling hole, and the terminal velocity of the airflow at the open end of the purge airflow sleeve. S3. Evaluate and judge the initial geometric structure using a quantitative evaluation model. The evaluation and judgment include: Establish a particle motion compliance assessment model based on the Stoke number, calculate the Stoke value by inputting the characteristic velocity of the airflow, and compare it with the preset threshold conditions for judgment; A cyclone separation efficiency evaluation model based on the critical separation diameter is established. The critical separation particle size is calculated by inputting the tangential velocity component of the airflow and compared with the lower limit of the target pollutant particle size. Establish an air curtain barrier effectiveness assessment model based on outlet dynamic pressure, input the airflow terminal velocity to calculate the outlet dynamic pressure value at the open end, and compare it with the static pressure of the engine compartment environment to make a judgment; S4. If any evaluation judgment result in step S3 fails to meet the corresponding preset judgment condition, the initial geometric structure is readjusted based on the flow field analysis results, and steps S2 to S4 are repeated until the geometric structure after iterative adjustment meets all preset judgment conditions.

7. The design method as described in claim 6, characterized in that, The calculation formula for the particle motion compliance assessment model is as follows: ； in, St For the Stokes number, τ p For particle relaxation time, u The characteristic velocity of the airflow within the airflow cavity. L The characteristic length of the airflow cavity. d p The particle size of the contaminant particles, ρ p For the density of polluting particles, μ f For the gas dynamic viscosity, the preset threshold condition is: St≤1 .

8. The design method as described in claim 6, characterized in that, The calculation formula for the cyclone separation efficiency evaluation model is as follows: ; in, d c For the critical separation particle size, ρ p For the density of polluting particles, μ f The viscosity is the dynamic viscosity of the airflow. u ω The tangential velocity component of the airflow. r The characteristic radius of the vortex; The preset condition is that the critical separation particle size is less than the lower limit of the target pollutant particle size.

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