A control device for controlling the Mach number of the nozzle exit under the regulation of the back pressure of the throat

Abstract

The application discloses a control device for the Mach number of the nozzle outlet under the regulation of the throat back pressure, belongs to the field of the control of the exhaust system of an aero-engine, and can realize the control of the outlet Mach number through the regulation of the back pressure at the nozzle throat, so that the multi-mode switching of the aircraft propulsion system is achieved. The application comprises a main flow nozzle, a flow control section and a flow stabilization section. The main flow nozzle is a two-dimensional rectangular nozzle, which can provide the required main jet flow and the throat control point for the control device and method. The jet flow is controlled through the bilateral expansion type fixed wall and the passive secondary flow aerodynamic constraint in the flow control section and the flow stabilization section, so that the outlet Mach number is changed. The application does not need complex mechanical hydraulic moving parts, active auxiliary devices such as high-pressure gas sources, has the advantages of fixed nozzle part profile, fast jet flow control response and the like, and can realize the demand output of multiple outlet Mach numbers under the constant pressure ratio state only through the combined action of the expansion type fixed wall and the passive secondary flow aerodynamic constraint.

Description

Technical Field

[0001] This invention belongs to the field of aero-engines, and in particular to a novel control strategy applied to aero-engine exhaust systems. Specifically, it relates to a control device for the nozzle exit Mach number under throat back pressure regulation. Background Technology

[0002] Throat control technology is currently a hot research topic in fixed geometry nozzle flow regulation control. Aircraft often face transitions between afterburner and cruise modes during flight. These transitions require simultaneous adjustments to the engine speed and nozzle profile via a mechanical control system to achieve mode switching. However, the complexity of the transition process increases flight control adjustment time and reduces aircraft maneuverability. Therefore, flow control methods at the throat have gradually attracted attention. Throat control methods can control the nozzle flow rate to change the nozzle exit Mach number. Currently, throat control technology is broadly divided into mechanical throat control and aerodynamic throat control. Mechanical throat control technology mainly adjusts the nozzle throat area through actuators and flexible curves. This control method is simple, but suffers from drawbacks such as large mechanical structure weight and complex mechanical control system, increasing the overall weight of the propulsion system. Aerodynamic throat technology mainly utilizes secondary flow injection from different angles to achieve a choking effect, ultimately changing the nozzle exit Mach number. This control method controls the throat area by injecting an active jet at the throat, reducing some of the complex mechanical structures and featuring a fixed throat profile and fast control response. However, the additional high-pressure bleed air from the engine increases the burden on the propulsion system, leading to a larger overall system weight, increased control energy consumption, and increased thrust loss. Furthermore, mitigating these drawbacks requires comprehensive consideration of the secondary flow injection angle, pressure, and quantity. Addressing the shortcomings of current mechanical and pneumatic throat control technologies, this invention proposes a novel flow control method that achieves the required nozzle exit Mach number simply by changing the amount of passive secondary flow ejected. This control method requires no additional high-pressure air source and offers significant advantages such as a fixed throat profile, simple structure, low control energy consumption, and fast response, thus possessing strong research and engineering application value. Summary of the Invention

[0003] This invention is based on a main nozzle, with multiple sections of expanding solid walls and passive secondary flow aerodynamic constraints arranged at the nozzle exit. Back pressure regulation at the main nozzle throat is achieved through throttling control of the passive secondary flow, thereby altering the jet expansion and ultimately changing the Mach number at the nozzle exit.

[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: a control device for the Mach number of a nozzle exit under back pressure regulation at the throat, with a thrust nozzle as the implementation object. The control device includes a main flow nozzle, a flow control section, and a flow stabilization section; multiple expanding solid walls are arranged on the upper and lower sides of the main flow nozzle exit, and passive secondary flow control slots are arranged on these expanding solid walls as aerodynamic constraints. One end of the control slot is connected to the static pressure chamber leading to the local environment, and the other end leads to the jet boundary.

[0005] The main flow nozzle is a binary rectangular nozzle. The flow control section includes upper and lower expanding solid walls and upper and lower first passive secondary flow aerodynamic constraints. A passive secondary flow control slot is arranged at the outlet of the main flow nozzle and one expanding solid wall. The flow stabilization section mainly includes upper and lower expanding solid walls and upper and lower second and third passive secondary flow aerodynamic constraints.

[0006] As a preferred technical solution, the mainstream nozzle is one or more of a convergent nozzle or a convergent-divergent nozzle.

[0007] As a preferred technical solution, the expanding solid wall is a multi-segment inclined straight wall, with each segment of the inclined straight wall forming a different angle with the nozzle axis.

[0008] As a preferred technical solution, the inclination angle of the first wall section is 10°-12°, and the inclination angle of the second wall section is 18°-24°.

[0009] As a preferred technical solution, one end of the first passive secondary flow control seam on the upper and lower sides of the flow control section is connected to the throat of the main jet outlet, and the other end is connected to the upper and lower expansion-type solid wall of the first section, which is used to control the back pressure on both sides of the main jet at the throat. At the same time, the first passive secondary flow control seam on the upper and lower sides forms a certain angle with the main flow direction. In the flow stabilization section, the second and third passive secondary flow control seams on the upper and lower sides are respectively arranged on the upper and lower expansion-type wall surfaces, with the same angle as the wall surface.

[0010] As a preferred technical solution, one end of the upper and lower first passive secondary flow static pressure chambers in the flow control section is connected to the upper and lower first throttling valves respectively, and the other end is connected to the upper and lower first passive secondary flow control slots respectively, so as to provide stable back pressure conditions for both sides of the jet.

[0011] As a preferred technical solution, one end of the upper and lower second and third passive secondary flow static pressure chambers in the flow stabilization section is connected to the upper and lower second and third throttling valves respectively, and the other end is connected to the lower second and third passive secondary flow control slots respectively, which are used to provide a stable environmental back pressure for the downstream jet and avoid random deflection of the jet.

[0012] As a preferred technical solution, the main nozzle has a fixed geometric shape and does not require the injection of active secondary flow. It adjusts the back pressure by controlling the self-ejection amount of passive secondary flow, which effectively changes the throat area and achieves the purpose of changing the degree of jet expansion to change the exit Mach number.

[0013] As a preferred technical solution, the throttle valve is connected to the static pressure chamber at one end and to the local environment at the other end. The throttle valve has the functions of throttling, controlling pressure and linear proportional control, and is used to provide a stable low-pressure environment for both sides of the jet.

[0014] As a preferred technical solution, under constant pressure ratio conditions of the propulsion system, minimum Mach number control is achieved by fully closing the throttle valve; maximum outlet Mach number output is achieved under this configuration by fully opening the throttle valve; and variable Mach number output is achieved by partially opening or proportionally adjusting the throttle valve.

[0015] As a preferred technical solution, three sets of passive secondary flow control slots are arranged in the nozzle flow direction. The first set of control slots is the main control point, and the control position is located at the junction of the main flow nozzle and the first expansion solid wall. The angle between the control slot and the main flow is 60°. The second and third sets of control slots are back pressure stabilization control points. The control positions are located at the junction of the two expansion solid walls and the end of the second expansion solid wall, respectively. The control slots are located on the wall surface and are parallel to the wall surface.

[0016] As a preferred technical solution, a regulating valve with a throttling function is connected to the outside of each static pressure chamber. This regulating valve has the function of adjusting the opening and closing degree of the channel, the flow rate, and the pressure.

[0017] Based on the above technical solutions, as a preferred technical solution, the regulating valve adopts one or more of the following: proportional valve, slide valve, vacuum valve, and solenoid valve.

[0018] Preferably, the present invention mainly achieves the effect of adjusting the degree of jet expansion by controlling the pressure of the first set of passive secondary flow channels on the multi-segment expansion solid wall, thereby changing the back pressure on both sides of the jet, and thus realizing the Mach number control at the nozzle exit.

[0019] The beneficial effects of this invention are:

[0020] Compared to conventional throat control methods, this approach, which involves arranging a passive secondary flow ejector channel and a multi-segment expanding solid wall at the main nozzle exit, can control the back pressure on both sides of the jet using only a regulating valve with a throttling effect, without the need for additional secondary flow generation devices or methods. This allows for changing the exit Mach number within a certain range at a constant pressure ratio, without requiring additional energy injection. It significantly reduces the structural weight of the entire propulsion system, simplifies the control mechanism, and improves response speed. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is an isometric view of a nozzle provided in an embodiment of the present invention;

[0023] Figure 2 This is a front view of a nozzle provided in an embodiment of the present invention;

[0024] Figure 3 This is a numerical schlieren image of the upper and lower first throttle valves when they are fully closed, provided in an embodiment of the present invention;

[0025] Figure 4 This is an experimental schlieren image of the upper and lower first throttle valves when they are fully closed, according to an embodiment of the present invention.

[0026] Figure 5 This is a numerical schlieren image of the upper and lower first throttle valves when partially open, according to an embodiment of the present invention;

[0027] Figure 6 This is an experimental schlieren image of the upper and lower first throttle valves partially open according to an embodiment of the present invention;

[0028] Figure 7 This is a numerical schlieren image of the upper and lower first throttle valves when they are fully open, provided in an embodiment of the present invention;

[0029] Figure 8 This is an experimental schlieren image of the upper and lower first throttle valves when they are fully open, according to an embodiment of the present invention.

[0030] Figure 9 This is an example of an embodiment of the present invention providing an outlet Mach number distribution diagram under different throttle valve conditions;

[0031] Among them, 1-mainstream nozzle, 21-flow control section, 22-flow stabilization section, 31-first stage upper expansion solid wall, 32-second stage upper expansion solid wall, 33-first stage lower expansion solid wall, 34-second stage lower expansion solid wall, 41-upper side first passive secondary flow static pressure chamber, 42-upper side second passive secondary flow static pressure chamber, 43-upper side third passive secondary flow static pressure chamber, 44-lower side first passive secondary flow static pressure chamber; 45-lower side second passive secondary flow static pressure chamber; 46-lower side third passive secondary flow static pressure chamber. Flow static pressure chamber; 51-Upper side first passive secondary flow control seam; 52-Upper side second passive secondary flow control seam; 53-Upper side third passive secondary flow control seam; 54-Lower side first passive secondary flow control seam; 55-Lower side second passive secondary flow control seam; 56-Lower side third passive secondary flow control seam; 61-Upper side first throttle valve; 62-Upper side second throttle valve; 63-Upper side second throttle valve; 64-Lower side first throttle valve; 65-Lower side second throttle valve; 66-Lower side second throttle valve. Implementation

[0032] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to specific embodiments.

[0033] This invention provides a method and apparatus for controlling the nozzle exit Mach number under throat back pressure regulation, referring to... Figure 1-9 The device and method are applied to a thrust nozzle, which includes a main flow nozzle 1, a flow control section 21, and a flow stabilization section 22.

[0034] In this embodiment, the main nozzle 1 is a rectangular converging nozzle with both the inlet and outlet being rectangular, mainly used to obtain a stable rectangular jet flow field.

[0035] In this embodiment, the flow control section 21 is the main control position in the device. The flow control section 21 mainly consists of an upper expansion solid wall 31, a lower expansion solid wall 33, an upper first passive secondary flow static pressure chamber 41, a lower first passive secondary flow static pressure chamber 44, an upper first passive secondary flow control slot 51, a lower first passive secondary flow control slot 54, an upper first throttle valve 61, and a lower first throttle valve 64.

[0036] In this embodiment, the flow stabilization section 22 is the jet stabilization part of the device. The flow stabilization section 22 is mainly composed of two upper expanding solid walls 32, two lower expanding solid walls 34, an upper second passive secondary flow static pressure chamber 42, an upper third passive secondary flow static pressure chamber 43, a lower second passive secondary flow static pressure chamber 45, a lower third passive secondary flow static pressure chamber 46, an upper second passive secondary flow control seam 52, an upper third passive secondary flow control seam 53, a lower second passive secondary flow control seam 55, and a lower third passive secondary flow control seam 56.

[0037] In this embodiment, the outlet of the main nozzle 1 is at the throat of the entire nozzle. An upper first passive secondary flow static pressure chamber 41 and a lower first passive secondary flow chamber 44 are arranged above and below the throat, respectively. One end of the upper first passive secondary flow static pressure chamber 41 is connected to an upper first passive secondary flow control slot 51, and the other end is connected to an upper first throttle valve 61. One end of the lower first passive secondary flow static pressure chamber 44 is connected to a lower first passive secondary flow control slot 54, and the other end is connected to a lower first throttle valve 64. The upper first passive secondary flow control slot 51 is connected to an upper expansion-type solid wall 31, and the lower first passive secondary flow control slot 54 is connected to a lower expansion-type solid wall 33.

[0038] In this embodiment, the upper second passive secondary flow control joint 52 in the flow stabilization section 22 is connected to the upper second passive secondary flow static pressure chamber 42, and the upper second passive secondary flow static pressure chamber 42 is also connected to the upper second throttle valve 62. The lower second passive secondary flow control joint 55 is connected to the lower second passive secondary flow static pressure chamber 45, and the lower second passive secondary flow static pressure chamber 45 is also connected to the lower second throttle valve 65. As the jet flows downstream, the other end of the upper second passive secondary flow control joint 52 is connected to the second-section upper expansion type solid wall 32, and the other end of the lower second passive secondary flow control joint 55 is connected to the second-section lower expansion type solid wall 34. The upper third passive secondary flow control joint 53 is connected to the upper third passive secondary flow static pressure chamber 43, and the upper third passive secondary flow static pressure chamber 43 is also connected to the upper third throttle valve 63. The lower third passive secondary flow control seam 56 is connected to the lower third passive secondary flow static pressure chamber 46, and the lower third passive secondary flow static pressure chamber 46 is connected to the lower second throttle valve 66.

[0039] The working principle of the nozzle in this embodiment is as follows:

[0040] In the non-acceleration state, i.e., when the Mach number requirement at the outlet is not high, the upper first throttle valve 61 and the lower first throttle valve 64 are closed. Simultaneously, to maintain downstream jet stability, the upper second throttle valve 62, the third throttle valve 63, the lower second throttle valve 65, and the third throttle valve 66 are fully open, facilitating access to the local environment. The jet exits from the main nozzle 1, and at the throat, the jet's entrainment effect draws gas from the upper and lower static pressure chambers. However, because the upper first throttle valve 61 and the lower first throttle valve 64 are closed, gas cannot be replenished in time. The back pressure on both sides of the jet gradually decreases at the throat, and the jet expands into a section of upper and lower expanding solid walls. Simultaneously, a shock wave structure forms downstream, increasing the pressure behind the wave and decreasing the Mach number. Meanwhile, because the upper and lower second and third throttle valves are open, the jet remains stable, and no random wall deflection occurs.

[0041] During acceleration, when the exit Mach number needs to increase, the upper first throttle valve 61 and the lower first throttle valve 64 are open. Simultaneously, to maintain downstream jet stability, the upper second throttle valve 62, the third throttle valve 63, the lower second throttle valve 65, and the third throttle valve 66 are fully open, venting to the local ambient atmosphere. The jet exits from the main nozzle 1, and at the throat, the jet's entrainment effect draws gas from the upper and lower static pressure chambers. Because the upper first throttle valve 61 and the lower first throttle valve 64 are in the open / closed state, gas can be replenished in a timely manner; that is, the back pressure on both sides of the jet can be regulated by the upper and lower throttle valves. The jet cannot expand to a section of upper and lower expanding solid walls, and no strong wave structure forms downstream, thus preventing the aforementioned pressure rise. At the same time, because the upper and lower second and third throttle valves are open, the jet remains stable, and no random wall deflection occurs.

[0042] This embodiment specifically includes the following working methods:

[0043] 1. The first throttle valves on both the upper and lower sides are fully closed.

[0044] Reference Figure 3 and Figure 4 When the upper and lower first throttle valves 61 and 64 are fully closed, the main jet with a pressure ratio of 3 is ejected from the main jet nozzle 1. The jet entrains the gas in the upper and lower first static pressure chambers 41 and 44, but because the throttle valves are fully closed, the gas cannot be replenished, causing the back pressure on both sides of the jet at the throat to gradually decrease, and the jet boundary expands to a section of the upper and lower expansion-type walls 31 and 33. Figure 3 As can be seen, the interaction between the jet and the solid wall boundary generates a shock wave structure. The shock wave causes an increase in pressure behind the wave and a decrease in the Mach number. The downstream upper and lower second and third throttling valves 62, 63, 65, and 66 are fully open, mainly to maintain the stability of the flow field at the jet outlet and ensure that the jet does not undergo random deflection. At this time, combined with Figure 9 The nozzle exit Mach number shows that the Mach number in the jet core region is between Ma0.9 and Ma0.95. This configuration is mainly used when the required Mach number for the aircraft is not high.

[0045] 2. The first throttle valves on both the upper and lower sides are partially open.

[0046] Reference Figure 5 and Figure 6 When the upper and lower first throttle valves 61 and 64 are partially open, that is, when the upper and lower first static pressure chambers 41 and 44 are partially connected to the local environment, the jet ejects the gas in the upper and lower first static pressure chambers 41 and 44. Simultaneously, the pressure within the static pressure chambers is regulated by the upper and lower first throttle valves 61 and 64. Compared to the completely closed state of the upper and lower first throttle valves 61 and 64, the gas can be partially replenished. Figure 4 It can be seen that although the jet boundary expands, it does not expand to the upper and lower expanding wall sections 31 and 33. The jet does not interact with the solid wall boundary to generate a shock wave structure, which also results in insufficient pressure rise to reduce the Mach number. At the same time, the downstream upper and lower second and third throttling valves 62, 63, 65, and 66 remain fully open, mainly to maintain the flow field stability at the jet outlet and ensure that the jet does not undergo random deflection. At this time, combined with Figure 9 The nozzle exit Mach number shows that the Mach number in the jet core region has recovered to Ma1.2-Ma1.3. This state is mainly used when the aircraft requires a medium Mach number, and it also shows that the exit Mach number can be controlled according to demand by controlling the opening and closing degree of the upper and lower first throttle valves 61 and 64.

[0047] 3. The first throttle valves on both the upper and lower sides are fully open.

[0048] Reference Figure 7 and Figure 8 When the upper and lower first throttling valves 61 and 64 are partially open, the upper and lower first static pressure chambers 41 and 44 are fully open to the local environment. The jet entrains the gas in the upper and lower first static pressure chambers 41 and 44, which is equivalent to the jet entraining gas from the downstream upper and lower second and third static pressure chambers 42, 43, 45, and 46. At this time, the gas can be fully replenished. The jet does not interact with the solid wall boundary to generate a shock wave structure, and the Mach number at the nozzle exit reaches the maximum Mach number under this pressure ratio and configuration. The downstream upper and lower second and third throttling valves 62, 63, 65, and 66 are fully open, mainly to maintain the stability of the flow field at the jet outlet and ensure that the jet does not undergo random deflection. At this time, combined with Figure 9 The nozzle exit Mach number shows that the Mach number in the jet core region is Ma1.4. It can be seen that the exit Mach number is uniform in this state, due to the absence of complex wave systems, allowing the jet to maintain a stable high Mach number over a large area of ​​the core region. This state represents the maximum exit Mach number achievable with this configuration and control method.

[0049] The beneficial effects of this invention are:

[0050] 1. The method and device for controlling the nozzle exit Mach number under throat back pressure regulation can achieve the regulation of the back pressure on both sides of the jet at the throat under a specified pressure ratio by using a simple throttle valve and other devices and methods, without the need for moving throat control mechanical parts or nozzle exit area control devices and methods. Ultimately, it can achieve the goal of controlling the exit Mach number within a certain range.

[0051] 2. By controlling the degree of throttle valve closure and achieving the required Mach number output according to flight conditions, multiple options can be provided for propulsion system operating conditions.

[0052] The above description is merely a specific implementation measure of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A control device for the nozzle exit Mach number under throat back pressure regulation, characterized in that: It includes a main nozzle, a flow control section, and a flow stabilization section; multiple expansion-type solid walls are arranged on the upper and lower sides of the outlet of the main nozzle, and passive secondary flow control slots are arranged on the multiple expansion-type solid walls as aerodynamic constraints. One end of the control slot is connected to the static pressure chamber and leads to the local environment, and the other end leads to the jet boundary. The main flow nozzle is a binary rectangular nozzle. The flow control section includes upper and lower expanding solid walls and upper and lower first passive secondary flow aerodynamic constraints. A passive secondary flow control slit is arranged at the outlet of the main flow nozzle and one of the expanding solid walls. The flow stabilization section includes upper and lower expanding solid walls and upper and lower second and third passive secondary flow aerodynamic constraints. The upper and lower second and third passive secondary flow control slits in the flow stabilization section are respectively arranged on the upper and lower expanding wall surfaces, with the same angle as the wall surfaces. One end of the upper and lower second and third passive secondary flow static pressure chambers in the flow stabilization section is connected to the upper and lower second and third throttling valves, respectively, and the other end is connected to the lower second and third passive secondary flow control slits, respectively, to provide a stable environmental back pressure for the downstream jet and avoid random jet deflection.

2. The control device according to claim 1, characterized in that: The mainstream nozzle is one or more of a convergent nozzle or a convergent-divergent nozzle.

3. The control device according to claim 1, characterized in that, The expanding solid wall consists of multiple inclined straight walls, each forming a different angle with the nozzle axis.

4. The control device according to claim 3, characterized in that: The first section of the wall has an inclination angle of 10°-12°, and the second section has an inclination angle of 18°-24°.

5. The control device according to claim 1, characterized in that, The first passive secondary flow control slots on the upper and lower sides of the flow control section are connected at one end to the throat of the main jet outlet and at the other end to the upper and lower expansion-type solid wall of the first section. They are used to control the back pressure on both sides of the main jet at the throat. At the same time, the first passive secondary flow control slots on the upper and lower sides form a certain angle with the main flow direction.

6. The control device according to claim 5, characterized in that, In the flow control section, one end of the upper and lower first passive secondary flow static pressure chambers is connected to the upper and lower first throttling valves, respectively, and the other end is connected to the upper and lower first passive secondary flow control slots, respectively, to provide stable back pressure conditions for both sides of the jet.

7. The control device according to claim 1, characterized in that, The main nozzle has a fixed throat geometry, requires no active secondary flow injection, and has no redundant actuation control components. It adjusts the back pressure by controlling the amount of passive secondary flow self-ejection, which effectively changes the throat area and is used to change the degree of jet expansion to achieve the purpose of changing the exit Mach number.

8. The control device according to claim 1, characterized in that, The throttle valve is connected to the static pressure chamber at one end and to the local environment at the other end. The throttle valve has the functions of throttling, controlling pressure and linear proportional control, and is used to provide a stable low-pressure environment for both sides of the jet.

9. The control device according to claim 1, characterized in that, Under constant pressure ratio conditions in the propulsion system, minimum Mach number control is achieved by fully closing the throttle valve; maximum outlet Mach number output is achieved under this configuration by fully opening the throttle valve; and variable Mach number output is achieved by partially opening or proportionally adjusting the throttle valve.

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