A design verification method and simulation test device for variable pitch propeller

Abstract

The present invention discloses a variable-pitch propeller design verification method and a dedicated simulation test device. The method adopts a variable-pitch propeller design verification method based on blade engineering multi-segment three-dimensional surface elements and PSP surface pressure distribution measurement technology. There is no need to use a large-scale wind tunnel to test the propeller, nor does it require a high-power engine / motor to drive the propeller to rotate. Only the surface pressure distribution of a series of three-dimensional surface elements needs to be measured in the test device proposed by the present invention. The method has the advantages of being applicable to a wide range of propellers, a relatively simple test system, low cost and high efficiency. It has more prominent advantages than full-scale wind tunnel tests and flight tests, is easier to implement, and has higher safety.

Description

Technical Field

[0001] The invention relates to a variable pitch propeller design verification method and a simulation test device, belonging to the technical field of aerospace. Background Art

[0002] Compared to jet propulsion systems, propeller-powered propulsion systems offer advantages such as high efficiency, long range, short takeoff and landing, and low cost. Constant-speed, automatic-pitch propellers are based on conventional fixed-pitch propellers and incorporate a variable pitch mechanism to adjust the pitch of the blades. This allows the propeller to maintain optimal speed under various flight conditions, ensuring optimal operation.

[0003] Propeller design involves optimizing the blade airfoil, chord, and twist angle distribution, targeting propeller efficiency η, under given conditions: propeller diameter D, number of blades N, propeller speed n, propeller shaft power P, and thrust T. The typical design approach involves preliminarily determining the number of blades, propeller diameter, and average chord length based on propeller power and maximum thrust requirements. The radial distribution of the blades is determined based on the characteristics of the selected airfoil family. The lift-to-drag ratio and stall angle of attack are optimized based on the airfoil's actual operating environment. The radial distribution characteristics of the airfoil (chord, twist angle, thickness, etc.) are then determined based on typical design points. For constant-speed, automatically variable-pitch propellers, in particular, it is necessary to optimize the airfoil distribution characteristics based on aerodynamic performance requirements at multiple design points, conduct verification and assessment of the propeller's aerodynamic performance under multiple operating conditions, and determine whether the aerodynamic performance meets the design requirements through propeller surface pressure calculations. If not, the blade shape or other parameters are modified and recalculated until the requirements are met. Obviously, this design approach is labor-intensive. In engineering, an estimation method is often used to divide the propeller blade into M segments along the radial direction. In this calculation model, the induced velocity at each control point in the M segments is solved to determine the circulation value, and the induced velocity at the control point and the midpoint of the spanwise attached vortex is calculated. Finally, according to the circulation lift theorem, the thrust and torque values ​​of the blade are calculated, ultimately obtaining the corresponding lift and drag coefficients. However, this method has low calculation accuracy and certain errors, requiring experimental verification of the estimated data. Therefore, conducting flow field test simulations and aerodynamic force measurements during the propeller design process has always been a key issue in verifying aerodynamic design.

[0004] The main means of conventionally implementing propeller design verification and flow field simulation measurement are: (1) wind tunnel scaled propeller test; (2) wind tunnel full-scale propeller test; (3) actual measurement of airborne propeller flight test. All three methods require the propeller to rotate, and then the propeller thrust and torque are measured by a high-precision multi-component force balance to calculate the efficiency. Wind tunnel scaled test cannot guarantee geometric similarity, kinematic similarity and dynamic similarity at the same time. It usually ignores the influence of Reynolds number and Mach number, and cannot meet the deformation similarity criterion. The choice of simulation conditions has a great influence on the measurement results. Full-scale propellers have high requirements for wind tunnel size. Under the premise of ensuring flow field uniformity, the wind tunnel size usually needs to be more than 2 times the propeller diameter. Most wind tunnels are difficult to meet the requirements of large-scale propeller testing, and the test cost is high. Flight test requires not only the coordination of the whole machine, but also supporting telemetry acquisition equipment. The test cost is high and the risk is high.

[0005] Pressure-Sensitive Paint (PSP) technology is a new optical surface pressure measurement method based on luminescent oxygen quenching. A special pressure-sensitive paint is applied to a model surface. Irradiated with light of a specific wavelength, the paint stimulates luminescence. By measuring the intensity of the emitted light, the corresponding pressure distribution can be calculated. Using PSP testing technology, wind tunnel testing of M-section propellers designed using engineering methods can measure the pressure distribution on both sides of each section. By integrating the three-dimensional pressure sections of the M-sections, the thrust and torque values ​​for the entire blade can be obtained, ultimately yielding the corresponding lift and drag coefficients. Summary of the Invention

[0006] The technical solution of the present invention is: to overcome the shortcomings of the existing technology, the present invention proposes a variable pitch propeller design verification method and simulation test device, based on the blade engineering multi-segment three-dimensional surface element and PSP surface pressure distribution measurement technology, to achieve variable pitch propeller flow field test simulation and high-precision aerodynamic measurement.

[0007] The technical solution of the present invention is:

[0008] A variable pitch propeller simulation test device, comprising a spoiler section, a contraction section, a test section, an air collecting nozzle, a return flow section, a diffuser section, a buffer section, a return flow section, and a test system;

[0009] The two ends of the contraction section, the test section, the gas collecting nozzle, the diffuser section, and the buffer section are connected in sequence and connected to the reflux section through a spoiler section to form a reflux closed space simulating a flow field environment;

[0010] The three-dimensional panel model of the variable-pitch propeller to be tested is mounted on a pitch angle adjustment device, which is then installed inside the test section.

[0011] The test system includes a camera, a lighting component, and a high-pressure gas component.

[0012] The camera and the lighting component are placed inside the test section, above the three-dimensional surface element model of the variable-pitch propeller to be tested, and the camera lens, focal length and lighting position are adjusted so that the camera's viewing angle range covers the three-dimensional surface element model; the high-pressure gas component is placed outside the test section, and is used to generate airflow and flow the airflow into the recirculation closed space.

[0013] Preferably, the high-pressure gas assembly includes a high-pressure gas generating device and an ejection device, the ejection device is connected to the high-pressure gas generating device, and the gas generated by the high-pressure gas generating device is sucked into the gas collecting nozzle through the ejection device at the gap where the test section is connected to the gas collecting nozzle.

[0014] Preferably, the lighting component is an LED array and a light sheet;

[0015] Preferably, the two spoiler sections have the same structure, both being semi-annular structures, and are located at both ends of the device;

[0016] The spoiler section includes a flow plate spoiler, a flow guide pipe and a honeycomb;

[0017] The spoiler is symmetrically installed inside the spoiler section, with both ends connected to the inner surface of the spoiler section; the guide pipe is parallelly installed in the center of the spoiler section; and the honeycomb is installed at the end of the spoiler section.

[0018] Preferably, the buffer section includes a power fan, and the power fan is installed at the end of the buffer section.

[0019] A variable pitch propeller design verification method, comprising:

[0020] (1) constructing a three-dimensional model of a propeller airfoil that meets the design requirements, segmenting the model, and processing a three-dimensional surface element model of each segment;

[0021] (2) installing a section of the three-dimensional panel model to be tested on a pitch angle adjustment device, wherein the pitch angle adjustment device is installed on the variable pitch propeller simulation test device according to claim 1;

[0022] (3) performing PSP spraying on the surface of the three-dimensional surface element model, wherein the coating comprises a shielding layer and an active layer; spraying the shielding layer first and then spraying the active layer; after the spraying is completed, the three-dimensional surface element model is allowed to stand for drying;

[0023] (4) Arranging a test environment consistent with the specified incoming flow conditions on the variable pitch propeller simulation test device, collecting the surface luminescence image of the three-dimensional surface element model when blowing, and calculating the surface pressure information; adjusting the pitch angle and repeating the above test multiple times to obtain the upper and lower surface pressure distribution within the specified angle range of the pitch angle;

[0024] (5) Each time a segment of the three-dimensional surface element model is replaced, steps (2) to (4) are repeated until the upper and lower surface pressure distributions of all segments of the three-dimensional surface element model at different pitch angles are obtained;

[0025] (6) The upper and lower surface pressure values ​​obtained from all segments of the three-dimensional surface element model are integrated and summed to obtain the propeller thrust, torque and efficiency information of the propeller airfoil model.

[0026] Preferably, polymethyl methacrylate, platinum porphyrin, trifluorotoluene and ethylene glycol solvent are mixed and stirred evenly, and then fumed silica that has been heated to remove adsorbed water is added and stirred thoroughly to form the active layer; epoxy resin and a mixed solvent are mixed and stirred for not less than 5 minutes, and the mixed solvent includes toluene, xylene, ethyl acetate and butanone, and then titanium dioxide that has been heated to remove adsorbed water is added, and stirring is continued on a centrifugal stirrer for not less than 3 hours to form the shielding layer.

[0027] Preferably, the PSP spraying thickness is 20-100 μm; wherein, the shielding layer thickness is 10-50 μm, and the active layer thickness is 10-50 μm.

[0028] Preferably, setting up the test environment includes:

[0029] Turn on the power fan, and the high-pressure gas generating device generates gas. The gas is sucked into the gas collecting nozzle through the ejection device at the gap between the test section and the gas collecting nozzle, and flows counterclockwise to the diffuser section and the buffer section. After being accelerated and pressurized by the power fan, it flows to the turbulence section; after flowing out of the turbulence section, it flows through the return section to another turbulence section. After two turbulences, a stable and uniform incoming flow is formed; after the incoming flow passes through the contraction section, under the premise that the flow rate remains unchanged, adjust the outlet area of ​​the contraction section and the speed of the power fan to make the airflow speed and total pressure entering the test section consistent with the specified incoming flow conditions; adjust the exposure time of the camera and the optical power of the light source so that the PSP stimulated radiation luminescence intensity under windless conditions is 30% to 70% of that under windy conditions.

[0030] Preferably, luminous images under different pressures are collected, and the luminous images are calibrated in a two-dimensional matrix to obtain a calibration coefficient matrix. The luminous image when blowing is divided by the reference image when not blowing, and multiplied by the calibration coefficient matrix, and finally the pressure value of the two-dimensional surface is obtained, that is, the light intensity is converted into the pressure distribution of the upper and lower surfaces.

[0031] Preferably, constructing a three-dimensional model of a propeller airfoil that meets the design requirements includes:

[0032] Obtain the design requirements for propeller diameter, number of blades, propeller speed, propeller shaft power and thrust, and target efficiency indicators;

[0033] Use a class function to fit the chord length distribution and twist angle distribution of an initial set of blades, and import the selected airfoil;

[0034] Calculate the blade chord length and thickness distribution according to the standard distribution function to determine the blade chord length and thickness distribution;

[0035] Using the propeller vortex theory and the calculation results of blade element aerodynamic characteristics, the propeller torsion angle distribution function is fitted after optimization, the blade torsion angle distribution is determined, and a three-dimensional propeller airfoil model that meets the design requirements is obtained.

[0036] The beneficial effects of the present invention compared with the prior art are:

[0037] (1) Easy to implement, low cost, and high efficiency. The test device used in the present invention does not require a large-scale test environment to test the propeller, nor does it require a high-power engine / motor to drive the propeller to rotate. It can provide stable and uniform incoming flow and total pressure to meet actual incoming flow conditions. It is only necessary to measure the surface pressure distribution of a series of three-dimensional surface elements in a small-scale test section. It has the advantages of being applicable to a wide range of propellers, a relatively simple test system, low cost, and high efficiency. It has more prominent advantages than full-scale wind tunnel tests and flight tests, is easier to implement, and has higher safety.

[0038] (2) High precision and better verification with the design method. Compared with the traditional wind tunnel scale test, the variable pitch propeller design verification method based on the blade engineering multi-segment three-dimensional surface element and PSP surface pressure distribution measurement technology adopted by the present invention can simultaneously ensure geometric similarity, motion similarity and dynamic similarity. Compared with the full-scale wind tunnel test, the PSP test on the single-segment three-dimensional surface element is less affected by the wall effect of the test device, has higher measurement accuracy, and is better verified with the surface element design results used in the design process. The pressure distribution characteristics and change laws on both sides of the surface element can be directly compared. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a flow chart of a design verification method for a variable pitch propeller according to an embodiment of the present invention;

[0040] Figure 2 A special propeller simulation test device according to an embodiment of the present invention;

[0041] Figure 3 This is a pitch angle adjustment device according to an embodiment of the present invention;

[0042] Figure 4 This is a measurement system and solution for an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, which are as follows:

[0044] A variable pitch propeller simulation test device, such as Figure 2 As shown, it includes a turbulent section, a contraction section 4, a test section 6, a reflow section 9, a diffuser section 11, a buffer section 12, a gas collecting nozzle 10, and a test system 8.

[0045] The two ends of the contraction section 4, the test section 6, the gas collecting nozzle 10, the diffuser section 11 and the buffer section 12 are connected in sequence and connected to the reflux section 9 through a spoiler section respectively, forming a reflux closed space that simulates the flow field environment.

[0046] Both flow-disrupting sections are semi-annular structures, located at either end of the device. The flow-disrupting sections include a spoiler 1, a flow guide 2, and a honeycomb 3, designed to guide the turbulent flow field and provide a uniform flow environment. The spoiler 1 is symmetrically mounted within the flow-disrupting section, with both ends connected to the inner wall of the section. The flow guide 2 is mounted parallel to the center of the section. The honeycomb 3, a porous, regular honeycomb structure, is mounted at the end of the section and can reduce flow pulsation and make the flow more uniform. For ease of explanation, the flow-disrupting section near the contraction section 4 is referred to as the first flow-disrupting section, and the other flow-disrupting section is referred to as the second flow-disrupting section.

[0047] The contraction section 4 is a wide-mouth trumpet-shaped structure with openings at both ends, which is used to adjust the wind speed at the inlet of the test section 6; the widest end face of the contraction section 4 is the inlet, which is connected to the spoiler section, and the other end face is an outlet with adjustable size, which is connected to the test section 6.

[0048] The buffer section 12 includes a power fan 13 installed at the end of the buffer section 12 .

[0049] The test section 6 is a square structure with a transparent top window, and the reflux section 9 is a flat rectangular structure.

[0050] like Figure 3 As shown, the three-dimensional surface element model 21 of the variable-pitch propeller to be tested is installed on the pitch angle adjustment device 23 through the support rod 22, and is installed inside the test section 6 through the pitch angle adjustment device 23; the surface of the three-dimensional surface element model 21 of the variable-pitch propeller to be tested is sprayed with pressure-sensitive coating with a spraying thickness of 20-100 μm; the coating includes a shielding layer and an active layer, the shielding layer has a thickness of 10-50 μm, and the active layer has a thickness of 10-50 μm.

[0051] The test system 8 includes a camera, an LED array and light sheet, a high-pressure gas generating device, an ejection device, an operating table, and a synchronous controller. The operating table is located inside the test section 6 and is a three-dimensional displacement operating platform for adjusting the camera placement. The synchronous controller is installed on the operating table, with a control accuracy higher than 1 microsecond and a control capability of more than 2 channels. The camera, LED array, and light sheet are placed inside the test section 6, above the three-dimensional surface element model 21 of the variable-pitch propeller to be tested. The synchronous controller controls the LED array to emit light and the camera to collect time series. The camera lens, focal length, and lighting position are adjusted so that the camera's viewing angle covers the three-dimensional surface element model; the high-pressure gas generating device and the ejection device are placed outside the test section 6. The high-pressure gas generating device generates gas, which is sucked into the gas collecting nozzle 10 through the ejection device at the gap where the test section 6 is connected to the gas collecting nozzle 12.

[0052] A design verification method for variable pitch propellers, such as Figure 1 As shown, including:

[0053] (1) Obtain the propeller diameter, number of blades, propeller speed, propeller shaft power and thrust, and target efficiency index required by the design, and construct a propeller airfoil model that meets the design requirements:

[0054] Use the class function to fit the chord length distribution and twist angle distribution of the blade, and import the selected airfoil:

[0055] Calculate the blade chord length and thickness distribution according to the standard distribution function to determine the blade chord length and thickness distribution;

[0056] Using propeller vortex theory and blade element aerodynamic characteristics calculation results, the propeller twist angle distribution function is fitted, the blade twist angle distribution is determined, and a propeller airfoil model that meets the design requirements is obtained.

[0057] The resulting 3D propeller airfoil model was segmented according to its chord length and diameter distribution while rotating. Adjacent airfoils with a chord length variation of no more than 10% were classified as segments. The aerodynamic lift and drag of each segment were estimated, and the strut length and diameter were designed based on these forces to meet support requirements. Test models of each segment, struts, and pitch angle adjustment device were then fabricated.

[0058] (2) Figure 3 As shown, a section of the three-dimensional surface element model 21 to be tested is mounted on the pitch angle adjustment device 23 via the support rod 22, and then mounted on the variable pitch propeller simulation test device. Based on the corresponding blade twist angle distribution obtained in step (1), the initial installation angle and pitch angle range of the three-dimensional surface element are determined. The pitch angle adjustment device 33 can adjust the pitch angle in 1° or 2° intervals.

[0059] (3) PSP spray coating is performed on the surface of the three-dimensional surface element model 21 mounted on the device, with a spray thickness of 20-100 μm. The coating includes a shielding layer and an active layer. The shielding layer is sprayed first, with a thickness of 10-50 μm, and the active layer is sprayed later, with a thickness of 10-50 μm. After spraying, the surface is left to dry.

[0060] The active layer is composed of: polymethyl methacrylate, platinum porphyrin, trifluorotoluene and ethylene glycol solvent are mixed and stirred evenly, and then fumed silica that has been heated to remove water adsorption is added and fully stirred to complete the process.

[0061] The shielding layer is composed of: mixing epoxy resin and a mixed solvent, which includes toluene, xylene, ethyl acetate and butanone, and stirring for not less than 5 minutes, then adding titanium dioxide that has been heated to remove water adsorption, and continuing to stir on a centrifugal stirrer for not less than 3 hours.

[0062] (4) On a variable pitch propeller simulation test device, a test environment is arranged, and the incoming wind speed and total pressure are controlled to be consistent with the actual incoming flow conditions of the three-dimensional panel model. The test is started and the luminous image during the blowing is collected to calculate the surface pressure information; the pitch angle is adjusted and the above test is repeated multiple times to obtain the upper and lower surface pressure distribution within the specified pitch angle range. This device allows the pitch angle to be between 0° and 360°.

[0063] The test environment layout includes:

[0064] Turn on the power fan, and the high-pressure gas generating device generates gas. The gas is sucked into the gas collecting nozzle through the ejector device at the gap between the test section and the gas collecting nozzle, and flows counterclockwise to the diffuser section and the buffer section. After being accelerated and pressurized by the power fan, it flows to the turbulence section; after flowing out of the turbulence section, it flows through the return section to another turbulence section. After two turbulences, a stable and uniform incoming flow is formed; after the incoming flow passes through the contraction section, it enters the test section. The inlet pressure P1 and fan speed V1 are adjusted by feedback from the total pressure and static pressure sensors installed on the test section, and the incoming flow velocity V2 and total pressure P2 are controlled to be consistent with the specified incoming flow conditions of the three-dimensional surface element model 21; through the above simulation of actual working conditions and the use of a 1:1 size model, it is ensured that the similarity conditions of the simulated three-dimensional surface elements meet the geometric similarity and motion similarity criteria.

[0065] like Figure 4 As shown, an LED array light source 31 and a camera 32 are placed directly above the 3D surface element model to be measured. A synchronization controller 33 controls the LED array light emission 31 and the camera 32 for data acquisition. The camera lens, focal length, and illumination position are adjusted so that the camera's field of view covers the entire 3D surface element model to be measured and the light source can evenly illuminate the coating on the surface of the 3D surface element model. The camera exposure time and the light power of the light source are adjusted so that the PSP stimulated emission luminescence intensity in windless conditions is 30% to 70% of that in windy conditions.

[0066] Based on the above-mentioned experimental environment, luminous images under different pressures were collected, and the luminous images were calibrated with a two-dimensional matrix to obtain a calibration coefficient matrix. The luminous image during blowing was divided by the reference image without blowing, and multiplied by the calibration coefficient matrix to finally obtain the pressure value of the two-dimensional surface, that is, converting the light intensity into the pressure distribution of the upper and lower surfaces.

[0067] (5) Each time a segment of the three-dimensional surface element model is replaced, steps (2) to (4) are repeated until the upper and lower surface pressure distributions of all segments of the three-dimensional surface element model at different pitch angles are obtained;

[0068] (6) The upper and lower surface pressure values ​​obtained from all segments of the three-dimensional surface element model are integrated and summed to obtain different distance ratios λ = V2 / (n·d) and power coefficients C P =P / (ρn 3 d 5 ) working conditions, where V2 is the incoming wind speed, n is the propeller speed, d is the propeller diameter, P is the propeller power, and ρ is the incoming flow density, characterizing the aerodynamic performance and propeller-engine matching effect of the propeller.

[0069] Existing propeller design verification and flow field simulation measurement methods require the propeller to rotate, and then use a high-precision multi-component force balance to measure the propeller's thrust and torque to calculate efficiency. Among them, wind tunnel scale testing cannot guarantee the simultaneous similarity of simulated quantities, ignores the effects of Reynolds number and Mach number, and fails to meet the deformation similarity criterion. The choice of simulation conditions has a significant impact on the accuracy of the measurement results. To ensure flow field uniformity, full-scale propellers usually require a wind tunnel size that is at least twice the propeller diameter. This is expensive, and most domestic wind tunnels are difficult to meet propeller testing requirements. Flight testing requires not only the coordination of the entire aircraft, but also supporting telemetry acquisition equipment, which is costly and risky. The variable-pitch propeller design verification method based on blade engineering multi-segment three-dimensional surface elements and PSP surface pressure distribution measurement technology adopted in the present invention does not require the use of a large-scale wind tunnel to test the propeller, nor does it require a high-power engine / motor to drive the propeller to rotate. It only needs to measure the surface pressure distribution of a series of three-dimensional surface elements in the test device proposed by the present invention. It has the advantages of a wide range of propellers, a relatively simple test system, low cost and high efficiency. It has more prominent advantages than full-scale wind tunnel tests and flight tests, is easier to implement, and has higher safety.

[0070] At the same time, compared with the traditional wind tunnel scale test, the design verification method adopted in the present invention can simultaneously ensure geometric similarity, motion similarity and dynamic similarity. Compared with the full-scale wind tunnel test, the PSP test on the single-segment three-dimensional surface element is less affected by the wall effect of the test device, has higher measurement accuracy, and is better verified with the surface element design results used in the design process, and can directly compare the pressure distribution characteristics and change laws on both sides of the surface element.

[0071] A wind tunnel test was conducted on a propeller with a diameter of 1m, a chord length of 0.1m and a rotation speed of 600r / min. According to the existing technology, the required wind tunnel test section size needs to be larger than 1.6m*1.6m diameter, and the incoming wind speed is 10-50m / s; using the test device of this patent, the radius of a 1m diameter blade is 0.5m, divided into 5 sections, each section is 0.1m in size and has a chord length of 0.1m. The test section size of this device only needs to be larger than 0.16m*0.16m, and the required incoming wind speed is slightly higher, at 10-80m / s.

[0072] According to theoretical analysis and a large number of tests, the test method proposed by this invention can achieve high-precision measurement. The specific data are as follows: The thrust coefficient C obtained by integrating the test data obtained by this patent test method N and torque coefficient C Mx , and the balance measurement results are shown in Table 1.

[0073] Table 1 Comparison of the test data obtained by the test method of the present invention and the balance measurement results

[0074]

[0075] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in this field.

Claims

1. A variable pitch propeller simulation test device, characterized in that: Including the spoiler section, contraction section, test section, gas collecting nozzle, reflux section, expansion section, buffer section and test system; The two ends of the contraction section, the test section, the gas collecting nozzle, the diffuser section, and the buffer section are connected in sequence and connected to the reflux section through a spoiler section to form a reflux closed space simulating a flow field environment; The three-dimensional panel model of the variable pitch propeller to be tested is mounted on a pitch angle adjustment device, which is then installed inside the test section. The test system includes a camera, a lighting component, and a high-pressure gas component; The camera and the lighting assembly are placed inside the test section, above the three-dimensional surface element model of the variable-pitch propeller to be tested, and the camera lens, focal length, and lighting position are adjusted so that the camera's viewing angle covers the three-dimensional surface element model; the high-pressure gas assembly is placed outside the test section, and is used to generate airflow and flow the airflow into the recirculation-type enclosed space; The high-pressure gas assembly includes a high-pressure gas generating device and an ejector device, the ejector device is connected to the high-pressure gas generating device, and the gas generated by the high-pressure gas generating device is sucked into the gas collecting nozzle through the ejector device through the gap at the connection between the test section and the gas collecting nozzle; the buffer section includes a power fan, and the power fan is installed at the end of the buffer section; During use, turn on the power fan and the high-pressure gas generating device to generate gas. The gas is sucked into the gas collecting nozzle through the ejector device at the gap between the test section and the gas collecting nozzle, and flows counterclockwise to the diffuser section and the buffer section. After being accelerated and pressurized by the power fan, it flows to the turbulence section; after flowing out of the turbulence section, it flows through the return section to another turbulence section. After two turbulences, a stable and uniform incoming flow is formed; after the incoming flow passes through the contraction section, under the premise that the flow rate remains unchanged, adjust the outlet area of ​​the contraction section and the speed of the power fan to make the airflow speed and total pressure entering the test section consistent with the specified incoming flow conditions.

2. A variable pitch propeller simulation test device according to claim 1, characterized in that: The lighting components are LED arrays and light sheets.

3. The variable pitch propeller simulation test device according to claim 1, characterized in that: The two spoiler sections have the same structure, both being semi-annular structures, and are located at both ends of the device; The spoiler section includes a flow plate spoiler, a flow guide pipe and a honeycomb; The spoiler is symmetrically installed inside the spoiler section, with both ends connected to the inner surface of the spoiler section; the guide pipe is parallelly installed in the center of the spoiler section; and the honeycomb is installed at the end of the spoiler section.

4. A variable pitch propeller design verification method, characterized in that: include: (1) constructing a three-dimensional model of a propeller airfoil that meets the design requirements, segmenting the model, and processing a three-dimensional surface element model of each segment; (2) installing a section of the three-dimensional panel model to be tested on a pitch angle adjustment device, wherein the pitch angle adjustment device is installed on the variable pitch propeller simulation test device according to claim 1; (3) performing PSP spraying on the surface of the three-dimensional surface element model, wherein the coating includes a shielding layer and an active layer; the shielding layer is sprayed first, and then the active layer is sprayed; After spraying, let the three-dimensional surface element model stand for drying; (4) Arranging a test environment consistent with the specified incoming flow conditions on the variable pitch propeller simulation test device, collecting the surface luminescence image of the three-dimensional surface element model when blowing, and calculating the surface pressure information; adjusting the pitch angle and repeating the above test multiple times to obtain the upper and lower surface pressure distribution within the specified angle range of the pitch angle; (5) Each time a segment of the three-dimensional surface element model is replaced, steps (2) to (4) are repeated until the upper and lower surface pressure distributions of all segments of the three-dimensional surface element model at different pitch angles are obtained; (6) The upper and lower surface pressure values ​​obtained from all segments of the three-dimensional surface element model are integrated and summed to obtain the propeller thrust, torque and efficiency information of the propeller airfoil model.

5. A variable pitch propeller design verification method according to claim 4, characterized in that: Polymethyl methacrylate, platinum porphyrin, trifluorotoluene and ethylene glycol solvent are mixed and stirred evenly, and then fumed silica that has been heated to remove adsorbed water is added and stirred thoroughly to form the active layer; epoxy resin and a mixed solvent are mixed and stirred for no less than 5 minutes, and the mixed solvent includes toluene, xylene, ethyl acetate and butanone, and then titanium dioxide that has been heated to remove adsorbed water is added, and stirring is continued on a centrifugal stirrer for no less than 3 hours to form the shielding layer.

6. A variable pitch propeller design verification method according to claim 4 or 5, characterized in that: The PSP spraying thickness is 20-100μm; among them, the shielding layer thickness is 10-50μm, and the active layer thickness is 10-50μm.

7. A variable pitch propeller design verification method according to claim 4, characterized in that: The exposure time of the camera and the optical power of the illumination component are adjusted so that the PSP stimulated radiation luminescence intensity under windless conditions is 30% to 70% of that under windy conditions.

8. The variable pitch propeller design verification method according to claim 4, characterized in that: Luminous images under different pressures are collected, and the luminous images are calibrated in a two-dimensional matrix to obtain a calibration coefficient matrix. The luminous image under blowing is divided by the reference image without blowing, and multiplied by the calibration coefficient matrix to finally obtain the pressure value of the two-dimensional surface, that is, converting the light intensity into the pressure distribution of the upper and lower surfaces.

9. The variable pitch propeller design verification method according to claim 4, characterized in that: Construct a 3D model of the propeller airfoil that meets the design requirements, including: Obtain the design requirements of propeller diameter, number of blades, propeller speed, propeller shaft power and thrust, and target efficiency indicators; Use a class function to fit the chord length distribution and twist angle distribution of an initial set of blades, and import the selected airfoil; Calculate the blade chord length and thickness distribution according to the standard distribution function to determine the blade chord length and thickness distribution; Using the propeller vortex theory and the calculation results of blade element aerodynamic characteristics, the propeller torsion angle distribution function is fitted after optimization, the blade torsion angle distribution is determined, and a three-dimensional propeller airfoil model that meets the design requirements is obtained.

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