CN115680933A - Throat offset type pneumatic vectoring nozzle with asymmetric concave cavity design - Google Patents
Throat offset type pneumatic vectoring nozzle with asymmetric concave cavity design Download PDFInfo
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- CN115680933A CN115680933A CN202211420601.9A CN202211420601A CN115680933A CN 115680933 A CN115680933 A CN 115680933A CN 202211420601 A CN202211420601 A CN 202211420601A CN 115680933 A CN115680933 A CN 115680933A
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Abstract
The invention discloses a throat offset type pneumatic vectoring nozzle with an asymmetric concave cavity design, which is characterized in that: the inner flow channel of the throat offset type pneumatic vectoring nozzle comprises a nozzle inlet, an equal straight section, a throat front convergence section, a throat, an asymmetric concave cavity and two throats which are sequentially communicated; the asymmetric concave cavity comprises two throat front expansion sections communicated with a throat and two throat front convergence sections communicated with the two throats; the upper part of the asymmetric concave cavity is an upper concave cavity, and the lower part of the asymmetric concave cavity is a lower concave cavity; the asymmetrical design of the concave cavity is realized in that the length of the lower concave cavity is greater than that of the upper concave cavity; the length of the expanding section of the lower concave cavity is larger than that of the expanding section of the upper concave cavity. By the asymmetrical design of the concave cavity, the self-vector angle, the asymmetrical vector angle and the radar signal shielding effect are obtained.
Description
Technical Field
The invention relates to the technical field of thrust vectoring nozzles of aeroengines, in particular to a throat offset type pneumatic vectoring nozzle with an asymmetric concave cavity design.
Background
The next generation of fighters requires that the aircraft have 4S capability, namely super stealth, supersonic cruise, super maneuver and super information advantage; the requirements for the exhaust system of the aircraft are greatly increased, and the aircraft is required to have extremely high maneuvering performance, namely the thrust vector exhaust system is necessarily selected.
The fluid thrust vectoring nozzle has the advantages of simple structure, light weight and the like, and is a research hotspot of various countries. The throat offset type pneumatic thrust vectoring nozzle is taken as a new type of pneumatic thrust vectoring nozzle, has the characteristics of simple overall structure and prominent vector performance, and is increasingly paid more attention. The traditional throat offset type pneumatic vectoring nozzle is in a double-throat form, and the specific structure of the traditional throat offset type pneumatic vectoring nozzle comprises a nozzle inlet, an equal straight section, a throat front convergence section, a throat, two throat front expansion convergence sections (concave cavities) and two throats.
The drag of the rear fuselage accounts for 38% -50% of the total fuselage drag of the aircraft, wherein 1/3 is caused by the jet nozzle and the rear fuselage. The flight and launch integration technology is a core technology of future combat aircrafts after a wing body fusion technology and a pneumatic stealth comprehensive technology. The core of the method is the integration of aircraft-engine pneumatics, structure and control. The exhaust system is required to be designed in a fusion mode with the rear fuselage, so that efficient inner and outer flow aerodynamic characteristics and good flight performance and quality in the envelope are achieved.
The normal working states of the throat offset pneumatic vectoring nozzle are divided into two types: the vector state is a non-vector state, and the working state is switched by the presence or absence of flow injection at a throat. By taking a vector state as an example, airflow is injected into the upper part or the lower part of one throat, the injected airflow exerts a vertical force on the flow of the main flow, the main flow generates disturbance and flows along one side wall surface of the expansion and convergence section at the front part of the two throats, the airflow turning effect is amplified and sprayed out through the action of the concave cavity, and finally the head raising or head lowering moment is generated. The air flow injected at a throat in the vector state can be an external air source, such as a high-pressure air bottle, an air pump, an aircraft external air flow and the like, or bleed air from a position higher than the pressure of the throat in an engine, such as the position of the rear part of a fan, a compressor and the like, or bleed air from the outlet of a turbine through a special channel to realize the self-adaptive passive control. Thus, throat offset aerodynamic vectoring nozzles are classified as active and passive depending on whether external bleed air is required.
However, through current research, in the flight process of an aircraft, due to the problem of trimming of the flight moment, the aircraft often needs to have a vector angle for the moment balance of the aircraft, and further, for example, the rear body lower edge plate is lengthened for shielding radar signals and enhancing stealth capability of the aircraft such as B2. Therefore, a method for designing the pneumatic vectoring nozzle which meets the stealth requirement and has an asymmetric vectoring angle is a problem to be solved urgently.
Disclosure of Invention
The purpose of the invention is as follows: in order to overcome the defects in the prior art, the invention provides the throat offset type pneumatic vector nozzle with the asymmetric concave cavity design, wherein the asymmetric concave cavity generates an asymmetric vortex system to provide a self-contained head raising/lowering vector angle in the take-off/flying requirements and generate an asymmetric head lowering/raising vector angle so as to solve the defects in the prior art.
The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that: a throat offset type pneumatic vector nozzle with asymmetric concave cavity design is characterized in that: the inner flow channel of the throat offset type pneumatic vectoring nozzle comprises a nozzle inlet, an equal straight section, a throat front convergence section, a throat, an asymmetric concave cavity and two throats which are sequentially communicated; the spray pipe is of a binary configuration;
the asymmetric concave cavity comprises two throat front expansion sections communicated with a throat and two throat front convergence sections communicated with the two throats; the upper part of the asymmetric concave cavity is an upper concave cavity, and the lower part of the asymmetric concave cavity is a lower concave cavity;
the asymmetrical design of the concave cavity is realized in that the length of the lower concave cavity is greater than that of the upper concave cavity; the length of the expanding section of the lower concave cavity is larger than that of the expanding section of the upper concave cavity. By the asymmetrical design of the concave cavity, the self-vector angle, the asymmetrical vector angle and the radar signal shielding effect are obtained.
The cavity comprises a cavity asymmetry angle γ satisfying:
wherein:
L 1 is the upper cavity length, L 2 The length of the concave cavity; d is a radical of 1 Length of the expanded section of the upper concavity, d 2 The length of the expansion section of the concave cavity; alpha (alpha) ("alpha") 1 Is the divergence angle, alpha, of the upper concavity 2 Is the divergence angle, beta, of the lower concavity 1 Angle of convergence of the upper bowl, beta 2 Angle of convergence of the upper cavity, D th1 Is a length of the throat, D th2 Two throat lengths.
Preferably, the cavity asymmetry angle γ is in the range 4 ° to 20 °. The length of the lower concave cavity and the length of the upper concave cavity satisfy L 2 =1.02L 1 ~1.15L 1 . Convergence angle beta of the lower cavity 2 The value range of (A) is 30-40 degrees. Divergence angle alpha of upper concavity 1 Divergence angle alpha from said lower concavity 2 And are equal. The above constraints may ensure that the cavity asymmetry angle γ is within the above ranges and may limit the range of other parameters not described.
Preferably, when the throat offset pneumatic vectoring nozzle with the asymmetric concave cavity design is in a vectoring state, the value range of the self-carrying vector angle is 0-10 degrees, and the main flow of the nozzle deflects to the upper side at the moment to provide a head raising moment for an aircraft.
Has the advantages that: compared with the prior art, the throat offset type pneumatic vectoring nozzle with the asymmetric concave cavity has the following advantages that:
(1) By the design of the asymmetric concave cavities, the concave cavities generate asymmetric vortices so as to provide self head-up/head-down vector angles in takeoff/flight requirements and generate asymmetric head-down/head-up vector angles.
(2) The asymmetric cavity and the rear body which are designed in a fusion mode provide radar signal shielding, and stealth performance is enhanced.
(3) The invention can be combined with the inventions of other modified throat offset type pneumatic vector nozzles and applied to the other modified throat offset type pneumatic vector nozzles.
Drawings
FIG. 1 is a schematic structural view of a throat offset pneumatic vectoring nozzle body according to the present invention;
FIG. 2 is a non-vector Mach number cloud chart of the throat offset type aerodynamic vectoring nozzle of the present invention;
FIG. 3 is a Mach number cloud chart of the low head vector state of the throat offset type pneumatic vectoring nozzle of the present invention;
FIG. 4 is a Mach number cloud diagram of the throat offset aerodynamic vectoring nozzle in the raised vector state;
FIG. 5 is a diagram of the non-vector state self-carrying vector angle change rule of the throat offset type pneumatic vectoring nozzle of the present invention;
FIG. 6 is a diagram of the law of vector angle change of the throat offset pneumatic vectoring nozzle of the present invention;
FIG. 7 is a diagram of thrust coefficients of the throat offset aerodynamic vectoring nozzle in a non-vectoring state in accordance with the present invention.
In the figure: 1-nozzle inlet, 2-equal straight section, 3-throat front convergence section, 4-throat, 5-two throat front expansion section, 6-two throat front convergence section, 7-two throat
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
As shown in figure 1, the nozzle structure comprises a nozzle inlet 1, an equal straight section 2, a throat front convergence section 3, a throat 4, two throat front expansion sections 5, two throat front convergence sections 6 and two throats 7 which are sequentially communicated. The nozzle is of a binary construction and figure 1 is a side view of the nozzle.
Wherein the expanding section 5 at the front part of the two throats and the converging section 6 at the front part of the two throats form the asymmetric concave cavity of the invention.
The upper part of the concave cavity is an upper concave cavity, and the lower part of the concave cavity is a lower concave cavity. Definition of L 1 To the upper cavity length, L 2 Length of the concave cavity, d 1 For the length of the upper cavity expansion segment, d 2 The length of the expanding section of the concave cavity is alpha 1 To the upper concave cavity divergence angle, α 2 At an angle of divergence, beta, of the concave cavity 1 To the upper cavity convergence angle, beta 2 To the upper cavity convergence angle, D th1 Is a throat length, D th2 Two throat lengths.
The asymmetry of the cavity may further cause asymmetry of the recirculation region within the cavity, and further, the wave system within the cavity may also be shifted so that a self-vectoring angle is still produced in the non-vectorial state. In a vector state, due to asymmetry of a concave cavity structure, upper and lower asymmetry is generated during upper/lower disturbance of a throat, further asymmetry of an upper/lower separation shock wave in the concave cavity is caused, and finally asymmetry of a vector angle is caused.
The throat offset pneumatic vector nozzle with the reference configuration has completely symmetrical upper and lower concave cavities, namely L 1 =L 2 ,d 1 =d 2 ,α 1 =α 2 ,β 1 =β 2 The cavity related parameters are coupled to each other.
In order to achieve the asymmetric design of the concave cavity, the invention adopts a method for controlling variables to design, and compared with the symmetric concave cavity, the throat area is constant, namely D th2 =1.2D th1 Upper cavity length L 1 And is not changed. Upper concave cavity expansion angle alpha 1 And the lower concave chamber expansion angle alpha 2 Equal, i.e. alpha 1 =α 2 . The cavity being of asymmetrical design, i.e. L 2 >L 1 ,d 2 >d 1 The remaining parameters are varied appropriately according to geometric constraints and design requirements.
Defining a cavity asymmetry angle gamma equal to
The asymmetric angle gamma of the concave cavity ranges from 4 DEG to 20 deg. On the premise of ensuring the angle, the length of the lower concave cavity is greater than that of the upper concave cavity, namely L 2 >L 1 And in the range L 2 =1.02L 1 ~1.15L 1 . Lower cavity convergence angle beta 2 The range of (a) is 30-40 degrees. The above constraint conditions can ensure that the asymmetric angle gamma of the concave cavity is within the range, and can limit the range of other parameters which are not described, and through the design of the geometric parameters, when the spray pipe is in a non-vector state, the self-vector angle range is 0-10 degrees. When the nozzle is in a vector state, asymmetry exists in the head raising/head lowering vector angles, and the difference value ranges from 3 degrees to 16 degrees. By the asymmetrical design of the concave cavity, the effects of asymmetrical vector angles and radar signal shielding are achieved.
Here is introduced a spanwise depth Lz, which is a depth at which the nozzle is stretched in the spanwise direction, as is common in the art. The entire nozzle Lz is identical. Throat area = Lz × D th When Lz is determined, by changing the corresponding throat length D th To control the corresponding throat area, so D th Can also be considered as a marker representing the relationship of the areas of the respective throats.
Fig. 2, 3 and 4 show mach number cloud charts of three states of a typical configuration of a throat offset type pneumatic vectoring nozzle with an asymmetric concave cavity design, and it can be seen that in a non-vectoring state, a self-carrying vector angle exists in the nozzle, a head-down vector is not equal to a head-up vector, and the head-up vector is obviously larger than the head-down vector. The cavity asymmetry may further cause asymmetry in the recirculation zone within the cavity, and further, the cavity wavefonn may also be shifted so that a self-vectoring angle is still produced in the non-vectorized state. In a vector state, due to asymmetry of a concave cavity structure, upper and lower asymmetry is generated during upper/lower disturbance of a throat, further asymmetry of an upper/lower separation shock wave in the concave cavity is caused, and finally asymmetry of a vector angle is caused.
Fig. 5, 6 and 7 show performance parameters of a throat offset pneumatic vectoring nozzle with a typical configuration and an asymmetric concave cavity design, and it can be seen that a self-contained vector angle can reach about 9 degrees, a thrust vector angle is asymmetric in a vector state, and compared with a basic configuration, the asymmetric concave cavity configuration has increased low head and head raising vector angles, and compared with the basic configuration, a thrust coefficient is slightly improved in a non-vector state. (EXAMPLE 1, 2, 3 are three typical configurations of asymmetric concave throat offset aerodynamic vector jet pipes based on the design criteria of the patent).
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention and these are intended to be within the scope of the invention.
Claims (7)
1. A throat offset type pneumatic thrust vectoring nozzle with an asymmetric concave cavity design is characterized in that: the inner flow channel of the throat offset type pneumatic vectoring nozzle comprises a nozzle inlet (1), an equal straight section (2), a throat front convergence section (3), a throat (4), an asymmetric cavity and two throats (7) which are sequentially communicated, and the throat offset type pneumatic vectoring nozzle is of a binary configuration;
the asymmetric concave cavity comprises two throat front expansion sections (5) communicated with a throat (4) and two throat front convergence sections (6) communicated with two throats (7); the upper part of the asymmetric concave cavity is an upper concave cavity, and the lower part of the asymmetric concave cavity is a lower concave cavity; the length of the lower concave cavity is greater than that of the upper concave cavity; the length of the expanding section of the lower concave cavity is larger than that of the expanding section of the upper concave cavity.
2. The asymmetric cavity design throat offset aerodynamic vectoring nozzle of claim 1 wherein said cavity includes a cavity asymmetry angle γ satisfying:
wherein:
L 1 is the upper cavity length, L 2 The length of the concave cavity; d is a radical of 1 Length of the expanded section of the upper concavity, d 2 The length of the expansion section of the concave cavity; alpha is alpha 1 Is the divergence angle, alpha, of the upper concavity 2 Is the divergence angle, beta, of the lower concavity 1 Angle of convergence of the upper cavity, beta 2 Angle of convergence of the upper cavity, D th1 Is a throatLength, D th2 Two throat lengths.
3. The asymmetric re-entrant design throat-offset aerodynamic vectoring nozzle as claimed in claim 2, wherein: the value range of the cavity asymmetric angle gamma is 4-20 degrees.
4. The asymmetric cavity design throat offset aerodynamic vectoring nozzle of claim 2 wherein: the length of the lower concave cavity and the length of the upper concave cavity are equal to L 2 =1.02L 1 ~1.15L 1 。
5. The asymmetric cavity design throat offset aerodynamic vectoring nozzle of claim 2 wherein: convergence angle beta of the lower cavity 2 The value range of (A) is 30-40 degrees.
6. The asymmetric cavity design throat offset aerodynamic vectoring nozzle of claim 3 wherein: divergence angle alpha of the upper concavity 1 Divergence angle alpha from the lower concavity 2 Are equal.
7. The asymmetric cavity design throat offset aerodynamic vectoring nozzle of claim 2 wherein: when the throat offset pneumatic vectoring nozzle with the asymmetric concave cavity design is in a vectoring state, the value range of the self-carrying vector angle is 0-10 degrees.
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