Design method of turboprop aircraft engine air inlet channel with foreign matter discharging function

Abstract

The invention provides a turboprop aircraft engine air inlet channel design method with a foreign matter discharging function. The turboprop aircraft engine air inlet channel design method comprises the steps that firstly, the performance requirement of an air inlet channel is determined; 2, designing detailed parameters of the air inlet channel; 3, the theoretical appearance of the air inlet channel is determined; and 4, verifying the theoretical appearance of the air inlet channel. Compared with a traditional turboprop aircraft air inlet channel, the air inlet channel designed through the method is high in total pressure recovery coefficient and uniform in flow field, can meet the air inlet flow and pressure requirements of an engine, has the foreign matter discharging function and prevents foreign matter in air from entering the engine. On the premise of ensuring the static strength design, the weight of parts is further reduced, and the fuel consumption rate of an aircraft is reduced.

Description

Technical Field

[0001] This invention relates to the field of power system technology in aircraft electromechanical systems, and specifically to a design method for an air intake duct of a turboprop aircraft engine with foreign object removal function. Background Technology

[0002] Aircraft air intakes are an important component of aircraft power systems. The curvature of their internal surfaces has a significant impact on the performance of the engine and even the overall aircraft. They must be able to withstand the pressure, vibration, and temperature generated during engine and aircraft operation, as well as the damage to the air intake caused by engine instability, including periodic changes in internal pressure and temperature and acoustic fatigue loads caused by compressor surge. Heating devices are also required to meet de-icing needs. Considering manufacturing economy and weight reduction, the materials must have good heat resistance and fatigue resistance and be designed with anti-icing features to ensure stable and reliable operation of the power unit within the flight envelope.

[0003] The air intake design of turboprop aircraft is demanding, requiring tolerance to marine environments, high humidity, salt spray, etc., while ensuring good flow field characteristics and structural strength, as well as low weight and bypassing foreign matter removal function. Summary of the Invention

[0004] In view of this, the present invention provides a design method for the air intake of a turboprop aircraft engine with foreign object removal function, so as to overcome the problems of large weight and high total pressure loss in the existing turboprop aircraft air intake design.

[0005] The present invention provides the following technical solution: a design method for an air intake duct of a turboprop aircraft engine with foreign object removal function, comprising: step one, determining the performance requirements of the air intake duct; step two, designing the detailed parameters of the air intake duct; step three, determining the theoretical shape of the air intake duct; and step four, verifying the theoretical shape of the air intake duct.

[0006] Compared with the prior art, the beneficial effects achieved by at least one of the above-mentioned technical solutions of the present invention include at least the following: compared with the traditional turboprop aircraft air intake, the air intake designed by this method has a high total pressure recovery coefficient, a uniform flow field, can meet the engine intake flow and pressure requirements, and has a foreign matter removal function to prevent foreign objects in the air from entering the engine. It also ensures static strength design while further reducing the weight of parts, thus reducing the aircraft's fuel consumption rate. Attached Figure Description

[0007] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0008] Figure 1 This is a flowchart of the design method for the air intake of a turboprop aircraft engine. Detailed Implementation

[0009] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0010] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0011] This invention employs a horizontal air intake and lateral foreign object discharge layout for the air intake duct; the air intake outlet has a heart-shaped cross-section. The air intake duct is installed using a quick-release method. The maximum permissible loads (including air loads) applied to the air intake duct mounting edge are as follows: shear load not exceeding 200N, cantilever moment not exceeding 50N•m. Figure 1 As shown, specifically, the design method for the turboprop aircraft engine air intake with foreign object removal function of the present invention includes the following steps: Step 1: Determine the intake manifold performance requirements; Step 2: Design the detailed parameters of the air intake; Step 3: Determine the theoretical shape of the air intake duct; Step 4: Verify the theoretical shape of the air intake.

[0012] The intake duct performance requirements in step one include: the intake duct total pressure recovery coefficient and the aerodynamic coefficient K.

[0013] Step two involves designing the detailed parameters for the air intake, specifically including the following: The inlet area, including the inlet area and the throat area, determines the maximum flow capture capacity of the inlet. Inlet area design needs to consider the total pressure loss of the airflow behind the propeller, as well as the effects of boundary layer suction flow and lateral overflow. The specific calculation formula is shown below: ……………………………(1) in: The theoretical capture area (㎡); Design the equivalent flow rate (kg / s) at the engine inlet; The Mach number of the incoming stream from a distance; The total pressure recovery coefficient of the airflow from the far front to the engine inlet intake duct; A coefficient to account for boundary layer suction flow and lateral overflow demand.

[0014] The inlet area of ​​the main airway is set at A0 to be 0.31 ± 0.02 m. 2 .

[0015] The determination of the intake throat area parameters mainly includes: The throat area of ​​the intake duct can be calculated using the following formula: ………………………………(2) In the formula, G is taken as 18 kg / s, and the intake total pressure recovery coefficient is initially selected. =0.992; The total pressure at the design point, The total temperature at the design point, Air quality at the design point It is an aerodynamic function. Let be the cross-sectional velocity coefficient. Therefore, the throat area of ​​the intake duct is 0.382 m².

[0016] The formula for the intake duct wall expansion angle is: ……………………………(3) In the formula: —Diffuser inlet area; —Diffuser outlet area; — Diffuser length.

[0017] The exit area of ​​the bypass can be calculated using the following formula: …………………………………(4) In the formula, G is taken as 3.6 kg / s, and the intake total pressure recovery coefficient is initially selected. =0.99; The total pressure at the design point, This is the total temperature at the design point. Therefore, the bypass exit area... =0.025m².

[0018] The mass flow rate G of the airflow entering the intake can be calculated using the following formula (5).

[0019] G=m …………………………………(5) In the formula: m = 0.0404; i represents the radial distribution number of the total pressure points, and j represents the circumferential distribution number of the total pressure points.

[0020] The converted mass flow rate GC of the airflow entering the bypass channel can be calculated using equation (6).

[0021] G C =G …………………………………(6) The M-number distribution of the exit measurement surface is defined as: ………………………………(7) The average M number of the exit measurement surface is defined as: ……………………………(8) Step three includes: the theoretical design of the air intake is based on the shape of the engine air intake, the shape of the aircraft nacelle, and the requirements of the engine for air intake flow rate, distortion coefficient, and foreign matter discharge, to obtain the preliminary position and size constraints of the air intake; after calculating the air intake area, the throat area of ​​the air intake, the shape and area of ​​the air intake outlet, the outlet area of ​​the bypass channel, and the expansion angle of the air intake wall through step two, the theoretical shape of the air intake can be basically determined.

[0022] Step four specifically involves: After clarifying the detailed design parameters of the air intake structure and startup, computational fluid dynamics software was used to conduct unpowered simulation calculations, performing typical operational calculations such as takeoff and cruise conditions. The parameterized flow field characteristics of the air intake under different flight profiles were calculated using simulation software. Based on the calculation and simulation results, improved locations for the air intake were proposed, and the air intake shape was optimized through calculation and simulation. Based on the optimized air intake shape, bird strikes were considered, and impact simulation analysis was used to optimize the inner surface of the air intake to meet the requirements of air intake deflection and flow field characteristics. Based on the optimized air intake shape, wind tunnel tests were conducted to verify the correctness of the theoretical calculations and to revise the calculation model.

[0023] Based on the initial position and size constraints of the air intake, the parameterized preliminary shape of the air intake is improved through fluid mechanics and turbulence theory, resulting in a parameterized preliminary shape based on the air intake.

[0024] In the calculations, the Mach number was 0.2-0.6, the nacelle angle of attack ranged from -10° to 21°, and the sideslip angle ranged from -25° to 0°. The inlet outlet distortion coefficient was obtained under different operating conditions. The inlet outlet distortion coefficient is defined as follows: …………………………………(9) In the formula: This represents the minimum average total pressure within the plane of the intake duct outlet. The average total pressure within the plane of the intake duct outlet; The dynamic pressure at the intake duct outlet plane position; Total pressure distortion The definition is the maximum total pressure measured at the inlet outlet section of the inlet. and minimum value The difference between The ratio of .

[0025]

[0026] Step four also includes: wind tunnel testing of a scaled-down inlet model.

[0027] The experimental model was scaled to 1:2. Under wind conditions, the internal flow performance of the nacelle inlet was obtained under typical conditions such as ground idle and takeoff power. This included the inlet's total pressure recovery coefficient, total pressure distortion index D, and the number of measurement surfaces (M) and static total pressure distribution at the inlet outlet. Basic experimental data for each design scheme was obtained, providing substantial data support for flight performance calculations and engine ground-based thrust tests. The impact of changes in bypass flow rate on the main engine inlet performance was also investigated, with comparative tests conducted on different bypass outlet area sizes. Finally, the influence of engine flow rate changes on bypass flow rate changes was determined.

[0028] Through combined tests of multiple schemes at large angles of attack and large sideslip angles, the maneuver envelopes of the aircraft nacelle air intake at low speeds that meet the engine intake distortion requirements were obtained.

[0029] Step four also includes: wind tunnel testing of a powered, scaled-down inlet model.

[0030] By conducting wind tunnel tests on a scaled-down inlet model with a power source, the outlet flow rate, total pressure distortion index, and total pressure recovery coefficient under different inlet flow rates were obtained. These results were compared with the wind tunnel test and simulation calculation structures of the scaled-down inlet model to provide a reference for iterative optimization.

[0031] Step four also includes: conducting a combined engine-intake bench test on the theoretical shape of the intake and a flight test on the theoretical shape of the intake. Both the combined engine-intake bench test and the flight test are routine tests and will not be described in detail here.

[0032] The air intake designed using the above design methods features a compact structure, low total pressure loss, high strength, light weight, small deformation, and simple and convenient installation and disassembly.

[0033] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical solutions, and technical solutions in this invention can be freely combined and used.

Claims

1. A design method for the air intake of a turboprop aircraft engine with foreign object removal function, characterized in that, include: Step 1: Determine the intake manifold performance requirements; Step 2: Design the detailed parameters of the air intake; Step 3: Determine the theoretical shape of the air intake duct; Step 4: Verify the theoretical shape of the air intake.

2. The design method for the air intake of a turboprop aircraft engine with foreign object removal function according to claim 1, characterized in that, The intake duct performance requirements in step one include: the intake duct total pressure recovery coefficient. And the aerodynamic coefficient K.

3. The design method for the air intake of a turboprop aircraft engine with foreign object removal function according to claim 2, characterized in that, Step two includes: pass Calculate the theoretical capture area of ​​the intake duct, where, This represents the theoretical capture area. Design the equivalent flow rate at the engine inlet; The Mach number of the incoming stream from a distance; The total pressure recovery coefficient of the airflow from the far front to the engine inlet intake duct; To take into account the boundary layer suction flow rate and lateral overflow requirements.

4. The design method for the air intake of a turboprop aircraft engine with foreign object removal function according to claim 3, characterized in that, Step two includes: pass Calculate the intake throat area, where G is the cross-sectional mass flow rate. The total pressure at the design point, The total temperature at the design point, Air quality at the design point It is an aerodynamic function. This is the cross-sectional velocity coefficient.

5. The design method for the air intake of a turboprop aircraft engine with foreign object removal function according to claim 4, characterized in that, Step two includes: pass Calculate the intake duct wall expansion angle; where, This refers to the diffuser inlet area. The diffuser outlet area; This is the length of the diffuser.

6. The design method for the air intake of a turboprop aircraft engine with foreign object removal function according to claim 5, characterized in that, pass Calculate the exit area of ​​the bypass passage.

7. The design method for the air intake of a turboprop aircraft engine with foreign object removal function according to claim 6, characterized in that, The third step specifically involves: determining the initial shape of the air intake based on the calculation results of the second step, performing multiple simulations on the initial shape of the air intake, and selecting the theoretical shape of the air intake that meets the design requirements from the various simulation results.

8. The design method for the air intake of a turboprop aircraft engine with foreign object removal function according to claim 6, characterized in that, Step four includes: pass Calculate the total pressure distortion and compare it with a set threshold to determine whether the intake meets the design requirements. The maximum total pressure was measured at the intake duct outlet section. The minimum total pressure measured at the intake duct outlet section.

9. The design method for the air intake of a turboprop aircraft engine with foreign object removal function according to claim 8, characterized in that, Step four includes: A scaled-down model of the intake was tested in a wind tunnel to determine the theoretical shape of the intake. Wind tunnel tests were conducted on a scaled-down model of the intake duct to determine its theoretical shape. A combined engine-intake bench test was conducted to determine the theoretical shape of the intake manifold. Flight tests were conducted on the engine and air intake to test the theoretical shape of the air intake.

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