Flow control method for backpack type bump air inlet channel of supersonic aircraft
By introducing micro jet holes into the intake duct of the load-type bulge in the supersonic aircraft, the problems of flow separation and outlet distortion are solved, and the flow field quality and engine performance of the intake duct are improved.
Patent Information
- Application Number
- CN202510886264.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-09-02
AI Technical Summary
The prior art is difficult to effectively control the flow separation and outlet distortion in the intake duct of the load-type bulge of the supersonic aircraft, affecting engine performance and stealth performance.
Micro jet holes are introduced into the intake channel, and the aperture size, spacing, pressure and jet direction are determined through numerical simulation analysis, and a gas-induced heat dissipation device is established to control flow separation and improve the flow field quality.
It significantly reduces the average steady-state circumferential distortion index of the intake outlet, improves the flow field quality and engine performance, and provides greater safety margin for the engine.
Smart Images
Figure CN120573265A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of aircraft engines, and in particular relates to a flow control method for a piggyback bulge air inlet of a supersonic aircraft. Background Art
[0002] The new generation of stealth aircraft is moving towards an ultra-flat layout and a dorsal-integrated propulsion system. This layout not only has excellent radar and infrared stealth performance, but also provides a larger internal usable space, which is conducive to the placement of internal bomb bays and landing gear on the belly.
[0003] As a crucial component of an aircraft's propulsion system, the air inlet is responsible for capturing, compressing, and rectifying the airflow. It is required to provide high-quality airflow to the engine throughout the entire flight envelope. The air inlet has a significant impact on the aircraft's propulsion system. For example, every 1% total pressure loss in a turbofan engine's inlet results in a 1.2% to 1.5% thrust loss. Furthermore, the swirl flow at the inlet's exit significantly reduces the turbofan engine's margin and efficiency. Furthermore, air inlet installation is constrained by aerodynamic layout and aircraft stealth requirements. This is particularly true for modern stealth fighters, unmanned combat aircraft, cruise missiles, and other aircraft, requiring significant attention.
[0004] In recent years, the S-bend air inlet has been favored by researchers at home and abroad due to its many advantages, such as compact structure, small frontal area, and good stealth performance. However, the expansion duct of the S-bend air inlet has a large airflow reverse pressure gradient. It is difficult for the airflow entering the S-bend air inlet to adhere to the extremely curved duct wall, and flow separation is prone to occur. At the same time, due to the action of centrifugal force, the pressure distribution on the upper and lower walls of the two bends is opposite, and the circumferential direction is driven by the lateral reverse pressure gradient, which easily produces severe secondary flow. At the same time, the distortion effect of the S-bend air inlet outlet is very obvious. It is very necessary to analyze the internal flow characteristics of the S-bend air inlet in detail and effectively improve the outlet airflow quality of the S-bend air inlet outlet through flow control or optimization methods.
[0005] The China Patent Literature Library has published a national invention patent (CN105775147) titled "Microjet Closed-Loop Flow Control Method under Subsonic Conditions." However, this national invention patent does not explain how to configure the microjet hole size or how to design the jet parameters.
[0006] Currently, there is an urgent need to develop a flow control method for the backpack-type bulge inlet of a supersonic aircraft. Summary of the Invention
[0007] The technical problem to be solved by the present invention is to provide a flow control method for a backpack-type bulge air inlet of a supersonic aircraft.
[0008] The method for controlling flow in a backpack-type bulge inlet of a supersonic aircraft of the present invention comprises the following steps: S10. Perform numerical simulation analysis; According to the incoming flow Mach number, the incoming flow parameters are set, and the internal flow of the S-bend inlet of the aircraft forebody and the backpack bulge inlet model is calculated through numerical simulation. The flow separation is analyzed after the bend of the S-bend inlet and the flow separation situation is analyzed. The surface pressure distribution and the surface limiting streamline at the flow separation position are plotted. S20. Draw separation line AB and control line CD; Based on the surface pressure distribution at the separation position and the distribution of the limiting streamlines on the object surface, a transverse separation line AB is drawn. A control line CD is drawn at a distance s upstream of the separation line AB as a reference line for the arrangement of the bleed air heat dissipation device. S30. Arrange several micro jet holes along the control line CD; Based on the numerical simulation results, the average thickness δ of the wall boundary layer on the control line CD is estimated, and the value range of the microjet aperture d is determined to be 0.3δ~0.5δ. Several microjet holes are arranged at equal intervals along the control line CD, and the spacing between each microjet hole is 7d~13d. S40. Determine the microjet pressure; The average static pressure p of the wall of the control line CD is estimated based on the numerical simulation results. The total jet flow rate of each micro-jet hole is controlled within 1% of the total flow rate of the inlet duct. In order to not affect the mainstream flow rate of the inlet duct, the micro-jet pressure range is determined to be 3p~10p. S50. Determine the jet direction of the microjet; According to the distribution of limiting streamlines on the object surface at the separation position and the requirement that the incident airflow affects the entire separation area, the flow direction angle and lateral angle of the microjet are determined; S60. Establish an air bleed heat dissipation device; A bleed air heat dissipation device is built. The bleed air heat dissipation device draws air from the aircraft's high-pressure air source, which enters the S-bend air inlet through each micro-jet hole, and the jet pressure is controlled by a pressure regulating valve. S70. Determine the control effect of micro-jet flow control; By calculating the distribution maps of the total pressure recovery coefficient at the S-bend inlet outlet in the uncontrolled state and the microjet flow control, the control effect of the microjet flow control is determined; the average steady-state circumferential distortion index of the microjet flow control can be reduced by up to 35% compared with the uncontrolled state, and the microjet flow control effect is obvious.
[0009] Furthermore, the air bleed heat dissipation device includes a cooling chamber, a pressure regulating valve, and an air collecting cavity connected in sequence along the airflow direction. Each micro jet hole draws air from the air collecting cavity separately through an air bleed pipe. The connection port between each air bleed pipe and the air collecting cavity is a tapered port, and the converging conical surface of the tapered port accelerates the flow rate of the air in the air bleed pipe. The curved surface of the air collecting cavity is conformally matched to the curved surface where the control line CD is located, and the distance between the two is less than or equal to 15d. The cooling chamber includes a cooling chamber box and a ventilation spiral pipe. The ventilation spiral pipe is connected to the aircraft high-pressure air source. The aircraft high-pressure air source is an aircraft engine, a high-pressure compressor or a separately set boost air source. The cooling chamber box is provided with an oil inlet and an oil outlet. The engine fuel is injected from the oil inlet, cools the air flow of the ventilation spiral pipe, and then flows out from the oil outlet. The air flow of the ventilation spiral pipe is continuously cooled through the circulation of the engine fuel.
[0010] The flow control method for a supersonic aircraft backpack-type bulge inlet of the present invention introduces a micro-jets at the bend of the backpack-type bulge inlet to destroy the strong separation vortex formed after the bend, reduce the low-energy zone formed at the inlet outlet, make the total pressure distribution at the inlet outlet more uniform, reduce the average steady-state circumferential distortion index at the inlet outlet, improve the flow field quality at the inlet outlet, improve the inlet performance, and leave a larger safety margin for the aircraft engine. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 Schematic diagram of separation line AB and control line CD and the distance s between them; Figure 2 Schematic diagram of the wall boundary layer thickness δ of the control line CD; Figure 3 Schematic diagram of the jet direction of the microjet; Figure 4 This is a schematic diagram of the principle of the air bleed heat dissipation device; Figure 4 In the middle, T1. Aircraft high-pressure air source; T2. Cooling chamber; T3. Gas collecting cavity; Figure 5 Schematic diagram of the connecting cone between the gas collecting cavity and the jet hole. DETAILED DESCRIPTION
[0012] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.
[0013] Embodiment: The supersonic aircraft backpack bulge inlet flow control method of this embodiment includes the following steps: S10. Perform numerical simulation analysis; According to the incoming flow Mach number, the incoming flow parameters are set, and the internal flow of the S-bend inlet of the aircraft forebody and the backpack bulge inlet model is calculated through numerical simulation. The flow separation is analyzed after the bend of the S-bend inlet and the flow separation situation is analyzed. The surface pressure distribution and the surface limiting streamline at the flow separation position are plotted. The unit Reynolds number of the S-bend inlet of this embodiment is approximately 6 million. By numerically simulating the flow separation occurring behind the internal bend of the S-bend inlet, the surface pressure distribution at the separation position and the limiting streamline distribution on the object surface were calculated, and the average steady-state circumferential distortion index at the outlet of the S-bend inlet was obtained to be 2.517%.
[0014] S20. Draw separation line AB and control line CD; Based on the surface pressure distribution at the separation position and the distribution of the limiting streamlines on the object surface, a transverse separation line AB is drawn. A control line CD is drawn at a distance s upstream of the separation line AB as a reference line for the arrangement of the bleed air heat dissipation device. like Figure 1 As shown, in this embodiment, referring to the object surface limit streamline, the curve where flow separation begins is found as the separation line AB, and a control line CD is drawn according to the requirement that the distance s between the separation line AB and the control line CD is approximately 14 mm; S30. Arrange several micro jet holes along the control line CD; Based on the numerical simulation results, the average thickness δ of the wall boundary layer on the control line CD is estimated, and the value range of the microjet aperture d is determined to be 0.3δ~0.5δ. Several microjet holes are arranged at equal intervals along the control line CD, and the spacing between each microjet hole is 7d~13d. like Figure 2 As shown, the average thickness δ of the wall boundary layer of the control line CD of this embodiment is about 4 mm, the micro jet aperture d is set to 2 mm, and the spacing between each micro jet hole is 10d, i.e. 20 mm; S40. Determine the microjet pressure; The average static pressure p of the wall of the control line CD is estimated based on the numerical simulation results. The total jet flow rate of each micro-jet hole is controlled within 1% of the total flow rate of the inlet duct. In order to not affect the mainstream flow rate of the inlet duct, the micro-jet pressure range is determined to be 3p~10p. S50. Determine the jet direction of the microjet; According to the distribution of limiting streamlines on the object surface at the separation position and the requirement that the incident airflow affects the entire separation area, the flow direction angle and lateral angle of the microjet are determined; The jet direction of the micro jet in this embodiment is shown in FIG. Figure 3 ; S60. Establish an air bleed heat dissipation device; A bleed air heat dissipation device is built. The bleed air heat dissipation device draws air from the aircraft's high-pressure air source, which enters the S-bend air inlet through each micro-jet hole, and the jet pressure is controlled by a pressure regulating valve. S70. Determine the control effect of micro-jet flow control; By calculating the distribution maps of the total pressure recovery coefficient at the S-bend inlet outlet in the uncontrolled state and the microjet flow control, the control effect of the microjet flow control is determined; the average steady-state circumferential distortion index of the microjet flow control can be reduced by up to 35% compared with the uncontrolled state, and the microjet flow control effect is obvious.
[0015] Furthermore, if Figure 4 、 Figure 5 As shown, the air bleed heat dissipation device includes a cooling chamber T2, a pressure regulating valve, and an air collecting chamber T3 connected in sequence along the air flow direction. Each micro jet hole draws air from the air collecting chamber T3 separately through an air bleed pipe. The connection port of each air bleed pipe to the air collecting chamber T3 is a tapered port, and the converging conical surface of the tapered port accelerates the flow rate of the air in the air bleed pipe. The curved surface of the air collecting chamber T3 is conformally matched to the curved surface of the control line CD, and the distance between the two is less than or equal to 15d. The cooling chamber T2 includes a cooling chamber box and a ventilation spiral tube. The ventilation spiral tube is externally connected to the aircraft high-pressure air source T1. The aircraft high-pressure air source T1 is an aircraft engine, a high-pressure compressor or a separately set boost air source. The cooling chamber box is provided with an oil inlet and an oil outlet. The engine fuel is injected from the oil inlet, cools the air flow of the ventilation spiral tube, and then flows out from the oil outlet. The air flow of the ventilation spiral tube is continuously cooled through the circulation of the engine fuel.
[0016] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the description and implementation methods. For those familiar with the art, all features disclosed in the present invention, or all steps in the disclosed methods or processes, 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 method for controlling the flow of a supersonic aircraft piggyback bulge inlet, characterized in that: The following steps are involved: S10. Perform numerical simulation analysis; According to the incoming flow Mach number, the incoming flow parameters are set, and the internal flow of the S-bend inlet of the aircraft forebody and the backpack bulge inlet model is calculated through numerical simulation. The flow separation is analyzed after the bend of the S-bend inlet and the flow separation situation is analyzed. The surface pressure distribution and the surface limiting streamline at the flow separation position are plotted. S20. Draw separation line AB and control line CD; Based on the surface pressure distribution at the separation position and the distribution of the limiting streamlines on the object surface, a transverse separation line AB is drawn. A control line CD is drawn at a distance s upstream of the separation line AB as a reference line for the arrangement of the bleed air heat dissipation device. S30. Arrange several micro jet holes along the control line CD; Based on the numerical simulation results, the average thickness δ of the wall boundary layer on the control line CD is estimated, and the value range of the microjet aperture d is determined to be 0.3δ~0.5δ. Several microjet holes are arranged at equal intervals along the control line CD, and the spacing between each microjet hole is 7d~13d. S40. Determine the microjet pressure; The average static pressure p of the wall of the control line CD is estimated based on the numerical simulation results. The total jet flow rate of each micro-jet hole is controlled within 1% of the total flow rate of the inlet duct. In order to not affect the mainstream flow rate of the inlet duct, the micro-jet pressure range is determined to be 3p~10p. S50. Determine the jet direction of the microjet; According to the distribution of limiting streamlines on the object surface at the separation position and the requirement that the incident airflow affects the entire separation area, the flow direction angle and lateral angle of the microjet are determined; S60. Establish an air bleed heat dissipation device; A bleed air heat dissipation device is built. The bleed air heat dissipation device draws air from the aircraft's high-pressure air source, which enters the S-bend air inlet through each micro-jet hole, and the jet pressure is controlled by a pressure regulating valve. S70. Determine the control effect of micro-jet flow control; By calculating the distribution maps of the total pressure recovery coefficient at the S-bend inlet outlet in the uncontrolled state and the microjet flow control, the control effect of the microjet flow control is determined; the average steady-state circumferential distortion index of the microjet flow control can be reduced by up to 35% compared with the uncontrolled state, and the microjet flow control effect is obvious.
2. The method for controlling flow in a piggyback bulge inlet of a supersonic aircraft according to claim 1, characterized in that: The air bleed heat dissipation device comprises a cooling chamber (T2), a pressure regulating valve, and an air collecting chamber (T3) connected in sequence along the air flow direction; each micro jet hole independently draws air from the air collecting chamber (T3) via an air bleed pipe; the connection port of each air bleed pipe to the air collecting chamber (T3) is a conical port, and the flow rate of the air flow in the air bleed pipe is accelerated by the contraction cone surface of the conical port; the curved surface of the air collecting chamber (T3) is conformally matched to the curved surface on which the control line CD is located, and the distance between the two is less than or equal to 15d; The cooling chamber (T2) includes a cooling chamber box and a ventilation spiral pipe. The ventilation spiral pipe is externally connected to an aircraft high-pressure air source (T1). The aircraft high-pressure air source (T1) is an aircraft engine, a high-pressure compressor or a separately set supercharged air source. The cooling chamber box is provided with an oil inlet and an oil outlet. The engine fuel is injected from the oil inlet, cools the air flow of the ventilation spiral pipe, and then flows out from the oil outlet. The air flow of the ventilation spiral pipe is continuously cooled by the circulation of the engine fuel.