A method for distributed boundary layer suction propulsion aircraft high speed wind tunnel testing

Abstract

The application belongs to the technical field of wind tunnel test, and discloses a distributed boundary layer suction propulsion aircraft high-speed wind tunnel test method, which comprises the following steps: determining the momentum boundary layer thickness at the inlet of the full-size distributed boundary layer suction propulsion aircraft duct fan inlet duct; determining the ratio of the momentum boundary layer thickness at the inlet of the duct fan inlet duct to the installation height of the duct fan; determining the model scale; determining the boundary layer length at the inlet of the duct fan inlet duct of the scaled model; determining the momentum boundary layer thickness at the inlet of the duct fan inlet duct of the scaled model; determining the installation height of the duct fan of the scaled model; determining the fixed transition position and the fixed transition mode of the scaled model; performing the powered test of the scaled model; performing the unpowered test of the scaled model; performing the duct fan installation height simulation test of the scaled model in the unpowered state; and correcting the duct fan height amplification simulation influence quantity. The test method determines the size and key test parameters of the scaled model, and has engineering practical value.

Description

Technical Field

[0001] This invention belongs to the field of wind tunnel testing technology, specifically relating to a high-speed wind tunnel testing method for a distributed boundary layer inhalation propulsion aircraft. Background Technology

[0002] Distributed boundary layer inhalation (DBI) propulsion aircraft utilize the high-speed rotation of ducted fans to remove the low-energy boundary layer from the aircraft surface, improving propulsion efficiency while also generating significant lift and drag reduction. This represents a key research area for current civil green aviation vehicles. High-speed aerodynamic performance data for DBI propulsion aircraft requires obtaining data through high-speed wind tunnel testing using scaled-down models. Because scaled-down models of DBI propulsion aircraft must not only satisfy geometric, kinematic, and dynamic similarity requirements but also accurately simulate the impact of the boundary layer on the propulsion system, existing testing methods cannot meet these requirements.

[0003] Currently, there is an urgent need to develop a high-speed wind tunnel testing method for distributed boundary layer inhalation propulsion aircraft. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a high-speed wind tunnel test method for a distributed boundary layer inhalation propulsion aircraft, so as to overcome the defects of the prior art.

[0005] The high-speed wind tunnel testing method for a distributed boundary layer intake propulsion aircraft of the present invention includes the following steps: S10. Determine the momentum boundary layer thickness at the inlet of the ducted fan inlet of a full-size distributed boundary layer inhalation propulsion aircraft. Based on turbulent boundary layer theory, the boundary layer thickness at the inlet of the ducted fan of a full-size distributed boundary layer inhalation propulsion aircraft is determined. and momentum boundary layer thickness ;in, This is the distance between the ducted fan inlet and the leading edge of the wing; S20. Determine the ratio of the momentum boundary layer thickness at the inlet of the ducted fan of a full-size distributed boundary layer inhalation propulsion aircraft to the installation height of the ducted fan; Determine the momentum boundary layer thickness at the inlet of the ducted fan of a full-size distributed boundary layer inhalation propulsion aircraft. θ Installation height of ducted fan h ratio λ = θ / h ; S30. Determine the model scaling ratio; Based on the maximum speed of a full-size ducted fan N and the maximum speed of small-sized ducted fans N' Determine the model scaling ratio K= N / N'This allows for the determination of the specific dimensions of the scaled-down model; S40. Determine the boundary layer length at the inlet of the ducted fan in the scaled-down model; Scaled-down model ducted fan inlet boundary layer length ; S50. Determine the momentum boundary layer thickness at the inlet of the ducted fan in the scaled-down model; Based on turbulent boundary layer theory, the boundary layer thickness at the inlet of the scaled-down model is determined. and momentum boundary layer thickness ; S60. Determine the installation height of the ducted fan in the scaled-down model; Keep λ The installation height of the ducted fan in the scaled-down model remains unchanged. h = λ θ = h θ / θ ; S70. Determine the fixed transition positions and fixed transition methods for the scaled-down model; A small-sized ducted fan is installed on the scaled-down model; a columnar transition strip with a height of 0.10 mm is pasted at 10% of the leading edge of the scaled-down model's wing to achieve a turbulent boundary layer morphology for the scaled-down model under wind tunnel testing conditions, so as to ensure that the boundary layer morphology of the scaled-down model is similar to that of the full-size distributed boundary layer inhalation propulsion aircraft. S80. Conduct a scaled-down model drive test; Aerodynamic characteristic test data C of a full-scale distributed boundary layer inhalation propulsion aircraft under powered conditions was obtained through wind tunnel tests using a scaled-down model. 动力 ; S90. Conduct a scaled-down model without power; Aerodynamic characteristic test data of a full-scale distributed boundary layer intake propulsion aircraft under unpowered conditions were obtained through scaled-down model wind tunnel tests. C 无动力 ; S100. Conduct a scaled-down model simulation test of the ducted fan installation height under no-power conditions; The installation height of the scaled-down model ducted fan was adjusted to a simulated height of 150mm. A wind tunnel test was conducted on the scaled-down model to obtain the simulated test characteristics of the ducted fan installation height. C' 无动力 ; S110. Correct the effect of ducted fan height amplification simulation.

[0006] Furthermore, S110 includes the following: Determine the aerodynamic impact Δ caused by the scaled-up simulation of the ducted fan installation height. C =( C 无动力 -C' 无动力 ), correct Δ C Subsequently, the corrected aerodynamic performance data of the full-scale distributed boundary layer inhalation propulsion aircraft were obtained. C 动力修正= C 动力 +( C 无动力 - C' 无动力 ).

[0007] The high-speed wind tunnel test method for distributed boundary layer inhalation propulsion aircraft of this invention starts from the aerodynamic performance characteristics of distributed boundary layer inhalation propulsion aircraft and turbulent boundary layer theory. Based on engineering estimation methods, it determines the boundary layer thickness at the inlet of the ducted fan of a full-size distributed propulsion aircraft and calculates the ratio of the momentum boundary layer thickness at the inlet of the ducted fan to the installation height of the ducted fan. λ Then, based on the maximum speed of the full-size ducted fan and the maximum speed of the small-size ducted fan, the model scale is determined, thereby determining the specific dimensions of the scaled-up model and the boundary layer length at the inlet of the ducted fan. Then, based on turbulent boundary layer theory, the momentum boundary layer thickness at the inlet of the scaled-up model ducted fan is determined. Then, maintaining... λ The installation height of the ducted fan in the scaled-down model remains unchanged. Then, by comparing the aerodynamic test data of the scaled-down model installation height simulation and the height-scaled simulation under no-power conditions, the aerodynamic influence Δ brought about by the height-scaled simulation of the ducted fan is determined. C Finally, the aerodynamic impact of the amplified simulation of the ducted fan installation height was corrected to determine the aerodynamic performance data of the distributed boundary layer intake ducted fan propulsion aircraft.

[0008] The high-speed wind tunnel testing method for distributed boundary layer intake propulsion aircraft of the present invention has the following advantages: First, the test method is scientific and reliable. Based on the performance characteristics of distributed boundary layer inhalation propulsion aircraft and the basic principles of experimental aerodynamics, the key core simulation parameters for the high-speed wind tunnel test of the scaled-down model of the distributed boundary layer inhalation propulsion aircraft were determined, ensuring the scientific nature of the test method from the source. Second, the experimental methods are practical for engineering applications; the calculation methods for key experimental simulation parameters are clearly given, and the specific process from parameter determination to data correction is given step by step, which is operable and conducive to understanding and implementation by designers and testers.

[0009] In summary, the high-speed wind tunnel test method for distributed boundary layer inhalation propulsion aircraft of the present invention establishes a method for amplifying and correcting the duct fan installation height by simulating the ratio of the boundary layer height at the inlet of the ducted fan of the distributed boundary layer inhalation propulsion aircraft to the installation height of the ducted fan, and determines the scaled-down model size and key test parameters of the high-speed wind tunnel test of the distributed boundary layer inhalation propulsion aircraft, which has practical engineering value. Attached Figure Description

[0010] Figure 1 A schematic diagram of the geometry of a distributed boundary layer inhalation propulsion aircraft. Figure 2 A schematic diagram of the boundary layer shape at the inlet of the ducted fan of a distributed boundary layer propulsion aircraft. Figure 3 This is a flowchart of the high-speed wind tunnel test method for a distributed boundary layer inhalation propulsion aircraft according to the present invention. Detailed Implementation

[0011] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0012] Example: Figure 3 As shown, the high-speed wind tunnel test method for a distributed boundary layer inhalation propulsion aircraft in this embodiment includes the following steps: according to Figure 1 The location of the ducted fan inlet of the full-size distributed boundary layer inhalation propulsion aircraft shown is (the fourth ducted fan in the middle of the left wing, from the leading edge of the wing). =600mm), calculate the boundary layer thickness and momentum boundary layer thickness under cruise conditions as follows: δ =1028mm and θ =99.9mm; according to Figure 2 The ducted fan of the full-size distributed boundary layer inhalation propulsion aircraft shown has a height of 1200 mm. Determine the momentum boundary layer thickness at the inlet of the ducted fan of the full-size boundary layer inhalation propulsion aircraft. θ Installation height of ducted fan h ratio λ for: λ = θ / h =0.08325; Based on the maximum speed of a full-size ducted fan N =21,000 RPM and maximum speed of small-sized ducted fan N' =168000 rpm, determine the model scaling ratio K =1:8; Based on model scaling K Calculate the distance from the inlet of the ducted fan to the leading edge of the wing in the scaled-down model. =75mm; 5) Calculate the boundary layer thickness and momentum boundary layer thickness at the inlet of the ducted fan in the scaled-down model. δ' =322.8mm and θ' =31.3mm; 6) Maintain the momentum boundary layer thickness at the inlet of the ducted fan intake. θ Installation height of ducted fan h ratio λ The actual installation height of the ducted fan in the scaled-down model remains unchanged. h = λ θ = h θ / θ =376mm; 7) Install the small-sized ducted fan on the scale model; attach a 0.10mm high columnar transition strip at 10% of the leading edge of the scale model's wing; 8) Obtain aerodynamic characteristic test data of a full-scale distributed boundary layer inhalation propulsion aircraft under powered conditions through scaled-down model wind tunnel tests. C 动力 ; 9) Obtain aerodynamic characteristic test data of a full-scale distributed boundary layer intake propulsion aircraft under unpowered conditions through unpowered wind tunnel tests using a scaled-down model. C 无动力 ; 10) Adjust the installation height of the scaled-down model ducted fan to the same simulated height (150mm), and obtain the ducted fan installation height simulation test characteristic data through a non-powered test. C' 无动力 ; 11) Determine the aerodynamic influence Δ of the ducted fan installation height in the scaled-up simulation. C =( C 无动力 - C' 无动力 ), correct Δ C Subsequently, the corrected aerodynamic performance data of the full-scale distributed boundary layer inhalation propulsion aircraft were obtained. C 动力修正= C 动力 +( C 无动力 - C' 无动力 ).

[0013] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in the present invention, or all steps in all methods or processes disclosed, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the present invention. The present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A high-speed wind tunnel testing method for a distributed boundary layer intake propulsion aircraft, characterized in that, The aforementioned test method includes the following steps: S10. Determine the momentum boundary layer thickness at the inlet of the ducted fan inlet of a full-size distributed boundary layer inhalation propulsion aircraft. Based on turbulent boundary layer theory, the boundary layer thickness at the inlet of the ducted fan of a full-size distributed boundary layer inhalation propulsion aircraft is determined. and momentum boundary layer thickness ;in, This is the distance between the ducted fan inlet and the leading edge of the wing; S20. Determine the ratio of the momentum boundary layer thickness at the inlet of the ducted fan of a full-size distributed boundary layer inhalation propulsion aircraft to the installation height of the ducted fan; Determine the momentum boundary layer thickness at the inlet of the ducted fan of a full-size distributed boundary layer inhalation propulsion aircraft. θ Installation height of ducted fan h ratio λ=θ / h ; S30. Determine the model scaling ratio; Based on the maximum speed of a full-size ducted fan N and the maximum speed of small-sized ducted fans N' Determine the model scaling ratio K=N / N' This allows for the determination of the specific dimensions of the scaled-down model; S40. Determine the boundary layer length at the inlet of the ducted fan in the scaled-down model; Scaled-down model ducted fan inlet boundary layer length ; S50. Determine the momentum boundary layer thickness at the inlet of the ducted fan in the scaled-down model; Based on turbulent boundary layer theory, the boundary layer thickness at the inlet of the scaled-down model is determined. and momentum boundary layer thickness ; S60. Determine the installation height of the ducted fan in the scaled-down model; Keep λ The installation height of the ducted fan in the scaled-down model remains unchanged. h'=λθ'=hθ' / θ ; S70. Determine the fixed transition positions and fixed transition methods for the scaled-down model; A small-sized ducted fan is installed on the scaled-down model; a columnar transition strip with a height of 0.10 mm is pasted at 10% of the leading edge of the scaled-down model's wing to achieve a turbulent boundary layer morphology for the scaled-down model under wind tunnel testing conditions, so as to ensure that the boundary layer morphology of the scaled-down model is similar to that of the full-size distributed boundary layer inhalation propulsion aircraft. S80. Conduct a scaled-down model drive test; Aerodynamic characteristic test data C of a full-scale distributed boundary layer inhalation propulsion aircraft under powered conditions was obtained through wind tunnel tests using a scaled-down model. 动力 ; S90. Conduct a scaled-down model without power; Aerodynamic characteristic test data of a full-scale distributed boundary layer intake propulsion aircraft under unpowered conditions were obtained through scaled-down model wind tunnel tests. C 无动力 ; S100. Conduct a scaled-down model simulation test of the ducted fan installation height under no-power conditions; The installation height of the scaled-down model ducted fan was adjusted to a simulated height of 150mm. A wind tunnel test was conducted on the scaled-down model to obtain the simulated test characteristics of the ducted fan installation height. C' 无动力 ; S110. Correct the effect of ducted fan height amplification simulation.

2. The high-speed wind tunnel testing method for a distributed boundary layer inhalation propulsion aircraft according to claim 1, characterized in that, S110 includes the following: Determine the aerodynamic impact Δ caused by the scaled-up simulation of the ducted fan installation height. C = ( C 无动力 - C' 无动力 ), correct Δ C Subsequently, the corrected aerodynamic performance data of the full-scale distributed boundary layer inhalation propulsion aircraft were obtained. C 动力修正= C 动力 +( C 无动力 - C' 无动力 ).

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