CN110805501B - Throat offset type pneumatic thrust vectoring nozzle with inner S-shaped bend - Google Patents

Throat offset type pneumatic thrust vectoring nozzle with inner S-shaped bend Download PDF

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CN110805501B
CN110805501B CN201910981594.1A CN201910981594A CN110805501B CN 110805501 B CN110805501 B CN 110805501B CN 201910981594 A CN201910981594 A CN 201910981594A CN 110805501 B CN110805501 B CN 110805501B
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throat
nozzle
central cone
line
edge
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CN110805501A (en
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黄帅
徐惊雷
俞凯凯
汪阳生
蒋晶晶
潘睿丰
陈匡世
宋光韬
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Nanjing University of Aeronautics and Astronautics
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Nanjing University of Aeronautics and Astronautics
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
    • F02K1/78—Other construction of jet pipes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
    • F02K1/06—Varying effective area of jet pipe or nozzle

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Nozzles (AREA)

Abstract

The invention discloses a throat offset pneumatic vectoring nozzle with an inner S-bend, wherein the inner channel comprises a nozzle inlet, an equal straight section, a throat front convergent section, a throat, two throat front expansion sections, two throat front convergent sections and two throats (nozzle outlets) which are sequentially communicated, a spindle-shaped central cone is arranged in a concave cavity formed by the two throat front expansion sections and the two throat front convergent sections, and the concave cavity of the traditional throat offset pneumatic vectoring nozzle is changed into a symmetrical S-bend channel by adopting the central cone with a special profile, so that the shielding of a turbine cascade and the inner channel at the front part of the nozzle of an engine is realized, and the special optimized nozzle rear outer profile is adopted, so that the low detectability of the nozzle is obviously improved on the premise of ensuring that the thrust vectoring performance is not greatly reduced; furthermore, the adjustment of the outlet area of the spray pipe can be realized by controlling the forward and backward movement of the central cone, the use envelope of the spray pipe is enlarged, and the flow stability under the low working pressure drop ratio is improved.

Description

Throat offset type pneumatic thrust vectoring nozzle with inner S-shaped bend
Technical Field
The invention relates to a throat offset type pneumatic thrust vectoring nozzle with an inner S-shaped bend, and belongs to the technical field of advanced thrust vectoring nozzles of aircraft engines considering radar stealth.
Background
With the development of scientific technology and the improvement of practical requirements, low detectability and high maneuverability gradually become important assessment indexes and evaluation standards of the next generation of military aircrafts.
To achieve high maneuverability, thrust vector aircraft engines have become an indispensable component. The core of the thrust vector aircraft engine for realizing the thrust vector function is a thrust vector spray pipe, and the traditional mechanical thrust vector spray pipe is complex in structure, poor in reliability and troublesome in maintenance.
At present, the fluid thrust vectoring nozzle gradually becomes a research focus and a research hotspot of each country by the characteristics of simple structure and light weight, and will enter engineering application in the near future. Among them, the throat offset pneumatic thrust vectoring nozzle is a new type of fluid thrust vectoring nozzle which has been developed in recent years, and is more and more favored by virtue of the characteristics of simple structure, light weight, good vectoring performance and the like. A common throat offset aerodynamic vectoring nozzle is a dual throat structure, with the area of the two throats being slightly larger than the area of the one throat (i.e., an expandable throat offset aerodynamic vectoring nozzle) being most common. The function realization principle is that disturbance is applied to one throat to enable the speed section of airflow at the throat to deflect, and then the disturbance is amplified in the expansion and convergence section at the front part of the two throats to generate a stable thrust vector. The throat offset pneumatic vector nozzle can be generally divided into an active type and a self-adaptive passive type, wherein the source of an air source for generating a thrust vector by the active type is mostly an external compressor, an air bottle or air introduced from a high-pressure part (mostly an air compressor) of an aeroengine, and the throat offset pneumatic vector nozzle is characterized in that the thrust vector angle changes little along with the working pressure drop ratio of the nozzle, but the thrust loss of the whole aeroengine is large; the self-adaptive passive type is characterized in that a self-adaptive bypass channel is arranged to guide high-pressure airflow at the inlet position of the spray pipe to the designated position of the spray pipe for injection, self-adaptively generates disturbance and finally realizes a thrust vector.
The implementation of low detectability requires a special design of the various components of the aircraft and of the engine. Common aircraft low detectability is divided into radar stealth and infrared stealth. And the radar reflection signal of the nozzle constitutes an important component of the low detectability of the backward direction of the aircraft. Therefore, it is extremely important to design a new generation thrust vectoring nozzle that combines high efficiency thrust vectoring to improve aircraft maneuverability with low radar reflected signals.
Therefore, the invention discloses a throat offset type pneumatic vectoring nozzle with an inner S-shaped curve, a central cone with a special profile is designed, a concave cavity (two throat front expansion convergence sections) of the throat offset type pneumatic vectoring nozzle is changed into the S-shaped curve, shielding of a turbine cascade of an engine and a channel in the nozzle is realized, a specially optimized outer profile of the nozzle is supplemented, the low detectability of the nozzle is obviously improved on the premise that the thrust vectoring performance is not greatly reduced, the function of adjusting the area of an outlet (two throats) of the nozzle is achieved, and the use envelope of the nozzle is enlarged.
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 vectoring nozzle with the inner S-shaped curve, the concave cavity (the expansion and convergence section at the front part of the two throats) of the throat offset type pneumatic vectoring nozzle is changed into the S-shaped curve channel by adopting the central cone with the special profile, the shielding of the turbine cascade of the engine and the channel in the nozzle is realized, the special optimized outer profile of the nozzle is supplemented, and the low detectability of the nozzle is obviously improved on the premise of ensuring that the thrust vectoring performance is not greatly reduced.
The technical scheme is as follows: in order to achieve the purpose, the invention adopts the technical scheme that:
a throat offset pneumatic vectoring nozzle with an inner S-shaped bend is disclosed, wherein an inner channel of the throat offset pneumatic vectoring nozzle comprises a nozzle inlet, an equal straight section, a throat front convergence section, a throat, two throat front expansion sections, two outer throat front convergence sections and two throats (nozzle outlets) which are sequentially communicated, and a fusiform central cone is arranged in a concave cavity formed by the front expansion sections of the two throats and the front convergence section of the two throats, through the change of the central cone to the inner flow passage of the nozzle, the concave cavity (the expanding and converging section at the front part of the two throats) of the traditional throat offset type pneumatic vector nozzle is changed into a symmetrical S-shaped passage, thereby realizing the shielding of the turbine blade cascade of the engine and the inner passage at the front part of the nozzle, being assisted by the outer profile of the nozzle with special optimization, on the premise of ensuring that the thrust vector performance is not greatly reduced, the low detectability of the spray pipe is greatly improved.
Because the blocking cone of the spray pipe completely shields strong scattering sources such as turbine blades of the spray pipe, the radar waves which are emitted into the spray pipe from the back of the spray pipe can be reflected and attenuated for multiple times in the S-shaped inner flow channel, the intensity of the radar waves reflected back along the original direction is greatly reduced, and the radar stealth inside the spray pipe is realized.
Common specific implementation forms of the invention are a binary formula and a ternary axisymmetric formula. The pneumatic vectoring nozzle is specifically described in a binary mode, and a throat offset mode with an unadjustable central cone. The common central cone has spindle-shaped section, basically symmetric lines, corresponding two-dimensional nozzle is formed by stretching the lines, except the pilot circle line, the reference line of the central cone is composed of IJ, JK, IJ 'and J' K, i.e. IJ and IJ ', JK and J' K are symmetric along the central line, and the point I and the point K are perpendicular to the central line. The determination of the quadrilateral IJKJ' requires that the following conditions are simultaneously satisfied:
(1) the quadrilateral IJKJ ' should be within the quadrilateral dee ', and the quadrilateral dee ' is still a quadrilateral that is symmetrical up and down along the center line. Wherein the quadrilateral DEFE' is determined by the following conditions: (a) the side DE is parallel to the side AB and the distance L from the side DE to the front expansion section AB of the two throats1Is the extension distance H from A' to side AB1100% -150% of the total throat diameter, and the distance L from the edge DE to the front expansion section AB of the two throats1Not less than 95% of a throat height AA'; (b) edge EF is parallel to BC, and distance L from edge EF to front convergence section BC of two throats2Is the extension distance H from A' to side AB1100% -150% of the total length of the throat, and the distance L from the edge EF to the front convergence section BC of the two throats2Not less than 75% -120% of the height CC' of the second throat, and L2＝(85％-120％)L1。
(2) The length of a diagonal line JJ 'of the quadrangle IJKJ' is at least larger than the minimum value of the height AA 'of one throat and the height CC' of two throats (spray pipe outlets), so that the projection of the inner molded surface of the spray pipe on a vertical plane is closed and is uninterrupted, namely, the central cone completely shields backward incident radar waves and the radar waves cannot directly irradiate the turbine blade cascade at the front part of the spray pipe.
Further, the angle of the quadrilateral IJKJ' satisfies a certain relationship: i, an acute angle formed by the edge IJ and the horizontal direction (the direction of the central line IK) is not less than an angle formed by the edge AB and the horizontal direction, namely the acute angle formed by the edge IJ and the horizontal direction is not less than the expansion angle of the expansion and convergence section at the front part of the two throats; II, an acute angle formed by the side JK and the horizontal direction is not smaller than an angle formed by the side BC and the horizontal direction, namely the acute angle formed by the side JK and the horizontal direction is not smaller than a convergence angle of the expansion and convergence section at the front part of the two throats; III, the intersection point of the extension line of the side IJ, the section AA ' of the throat and the extension line thereof is positioned below the point A ', and the highest intersection point is not beyond the point A '; IV, the intersection point of the extension line of the side JK, the section CC ' of the two throats and the extension line thereof is below the point C ' and is not beyond the point C ' at most. The edges IJ and J' K also need to satisfy similar requirements, and are not described herein. Particularly, the design of the edges IJ and IJ' has great influence on the vector performance of the vector nozzle, if the design is not proper, the vector performance of the nozzle after the central cone is added is reduced to 10% -20% of the vector performance of the nozzle without the central cone, and in an extreme case, the vector function of the nozzle is threatened to disappear; on the contrary, if the design is proper, the vectoring performance of the nozzle with the added central cone can be recovered to 70% -80% of the performance of the nozzle without the central cone, and the daily use requirement can be met.
Further, the quadrangle IJKJ 'is rounded at least at < J and < J'. The quadrangle IJKJ 'rounded at the positions of & lt J' still meets the requirements of closed and uninterrupted projection of the inner molded surface of the spray pipe on a vertical plane, so that the central cone completely shields backward incident radar waves and the radar waves cannot directly irradiate to the turbine blade cascade at the front part of the spray pipe. The above design steps can be repeated to complete the design of the quadrilateral IJKJ'. Generally, the quadrilateral IJKJ ' is rounded at ≤ J and ≤ J ' with a radius not less than 10% of a throat height AA ' to reduce flow loss due to sudden steering.
Furthermore, the channel formed by the front convergent sections of the two throats and the central cone cannot be an expansion channel, namely the outlet area of the channel formed by the JK and the BC is not larger than the inlet area, so that the radar waves are prevented from being reflected out of the nozzle due to the dihedral angle effect after being emitted into the nozzle from the rear. The channels formed by J ' K and B ' C ' are the same.
It should be noted that the flow passage behind the throat of a conventional nozzle (only one throat) should be expanded to further increase the velocity of the nozzle exhaust, but for this design, to further increase the radar stealth performance, and therefore slightly lose the thrust performance of the nozzle, the area of the flow cross section is primarily targeted for the best radar stealth performance and the best thrust vector performance, followed by the thrust performance. This is quite different from the common nozzle design approach.
Furthermore, according to whether the central cone can move or not, the central cone is divided into a central cone adjustable type and a central cone non-adjustable type. The adjustable central cone can move back and forth along the central line DF to realize the adjustment of the area of the two throats, enlarge the using envelope of the nozzle and increase the flow stability. For the throat offset type pneumatic thrust vectoring nozzle with the adjustable central cone and the inward S-shaped bend, the working envelope and the design working point of the nozzle are determined firstly. After the working envelope and the design point are determined, the design of the central cone is carried out, and the design of the central cone is as small as possible besides meeting the geometric constraint so as to reduce the blocking effect on the airflow in the spray pipe. The adjusting process comprises the following steps: in the maximum operating condition of the nozzle (i.e. the operating drop pressure ratio NPR is the highest), the central cone is in the most forward position in the quadrilateral DEFE'; along with the gradual reduction of the working pressure drop ratio of the spray pipe, the central cone gradually moves backwards, the minimum flow area of the flow passage in the spray pipe is changed from the position of the first throat to a passage which is clamped by the central cone and the front convergence section of the second throat, namely the maximum distance of the backward movement of the central cone is 15-35% of the length of the concave cavity; the position of the central cone is at the end when the lowest working pressure drop ratio of the spray pipe is reached, at the moment, the central cone cannot be contacted with the front convergent section of the two throats, and the rear sharp point of the central cone cannot protrude out of the sections of the two throats. By moving the central cone back and forth, the adjustment of changing the geometric area of the two throat outlets by 0-100% of the area of the outlet of the spray pipe can be realized theoretically, and the requirement of wide-envelope work of the spray pipe is met. Particularly for low working drop ratio (NPR is less than or equal to 3), the invention can effectively improve the flow stability.
In order to further improve the radar stealth performance of the rear part of the spray pipe, the rear body molded surfaces CL and C 'L' need to be optimally designed. The rear body profiles CL and C 'L' should be as planar as possible, taking into account the direction of the radar reflection, the angles between them and the horizontal plane being α and β, respectively. For most aircraft, α ═ β; in order to control the reflection direction and reduce the rear fuselage resistance, the smaller the alpha and beta are within the range of geometric allowance, the better the alpha and beta are; typically, α and β range from 30 ° to 60 °. The change of alpha and beta has little influence on the performance in the spray pipe, only changes the rear body resistance and the radar reflection performance of the aircraft, and the specific value of the change is combined with the overall design of the aircraft.
For the three-dimensional axisymmetric throat offset type pneumatic vectoring nozzle with the inner S-shaped bend, the internal structure of the three-dimensional axisymmetric throat offset type pneumatic vectoring nozzle is consistent with that of the two-dimensional inner S-shaped bend throat offset type pneumatic vectoring nozzle, and the design method is basically consistent. But the rear body profile needs to be designed comprehensively according to the characteristics of the rear body of the aircraft and keeps an approximate plane, and the rear body cannot be simply rotated. The adjustment rule of the adjustable type of the central cone is consistent with the foregoing description, and will not be described herein.
Furthermore, high-temperature-resistant wave-absorbing coatings are coated inside the front expansion and convergence sections of the central cone and the second throat of the spray pipe, so that the backward radar stealth performance of the spray pipe is further improved.
Has the advantages that: compared with the prior art, the throat offset pneumatic vectoring nozzle with the inner S-shaped bend has the following advantages:
1. compared with the traditional throat offset type pneumatic vectoring nozzle, the invention changes the concave cavity (the expansion and convergence section at the front part of the two throats) of the traditional throat offset type pneumatic vectoring nozzle into the symmetrical S-shaped channel by adopting the central cone with a special profile, realizes the shielding of the inner channels at the front part of the engine turbine blade cascade and the nozzle, is assisted by the specially optimized outer profile of the nozzle, obviously improves the radar stealth of the nozzle on the premise of ensuring that the thrust vectoring performance is not greatly reduced, and reduces the radar reflection sectional area RCS;
2. compared with the traditional throat offset type pneumatic vectoring nozzle, the invention can realize the adjustment of the area of the two throats (outlets) of the nozzle only by moving the central cone back and forth, has simple structure, can effectively widen the working envelope of the nozzle, increases the flow stability, and is suitable for binary and ternary axisymmetric nozzles;
3. the same idea can be used in throat offset type pneumatic vectoring nozzle with other function modifications, and the throat offset type pneumatic vectoring nozzle is good in applicability and wide in application.
Drawings
FIG. 1 is a cross-sectional view in parallel flow of the present invention;
FIG. 2 is a cross-sectional view of the diverging and converging section of the front of the two throats of the present invention in a parallel flow direction;
FIG. 3 is a schematic structural view of the present invention;
FIG. 4 is a cross-sectional view in parallel flow of an embodiment of the present invention;
FIG. 5 is a performance curve diagram of thrust vector angles of three configurations of spray pipes of the embodiment of the invention along with changes of working drop ratios;
the figure includes: 1. the nozzle comprises a nozzle inlet, 2 equal straight sections, 3 a throat front convergence section, 4 a throat, 5 a central cone, 6 a two throat front expansion section, 7 a two throat front convergence section, 8 a nozzle rear external profile, 9 a two throat (nozzle outlet).
Detailed Description
The present invention will be further described with reference to the accompanying drawings.
FIG. 1 shows a throat offset aerodynamic vectoring nozzle with an inner S-bend, comprising a throat offset aerodynamic vectoring nozzle and a center cone disposed in the throat offset aerodynamic vectoring nozzle;
the inner molded surface of the throat offset type pneumatic vectoring nozzle is of a common and classical double-throat structure and specifically comprises a nozzle inlet 1, an equal straight section 2, a throat front convergence section 3, a throat 4, two throat front expansion sections 6, two throat front convergence sections 7 and two throats (nozzle outlets) 9 which are sequentially communicated, and a specially designed central cone 5 is arranged in a concave cavity formed by the two throat front expansion sections 6 and the two throat front convergence sections 7.
The concave cavity (expanding and converging section at the front part of the two throats) of the traditional throat offset type pneumatic thrust vectoring nozzle is changed into a symmetrical S-shaped channel through the central cone 5, so that the shielding of the turbine cascade of the engine and the inner channel at the front part of the nozzle is realized, and the special optimized outer surface of the nozzle is supplemented, so that the low detectability of the nozzle is obviously improved on the premise of ensuring that the thrust vectoring performance is not greatly reduced.
Common specific implementation forms of the invention are a binary formula and a ternary axisymmetric formula. The pneumatic vectoring nozzle is specifically described in a binary mode, and a throat offset mode with an unadjustable central cone. The common central cone section is spindle-shaped, basic molded lines are symmetrical up and down, the corresponding binary-configuration spray pipe is formed by stretching molded lines, except for the molded line of a pilot circle, the reference molded line is composed of IJ, JK, IJ 'and J' K, namely IJ, IJ ', JK and J' K are symmetrical along a central line, and a point I and a point K are perpendicular to the central line. The determination of the quadrilateral IJKJ' requires that the following conditions are simultaneously satisfied:
(1) the quadrilateral IJKJ ' should be within the quadrilateral dee ', and the quadrilateral dee ' is still a quadrilateral that is symmetrical up and down along the center line. Wherein the quadrilateral DEFE' is determined by the following conditions: (a) the side DE is parallel to the side AB and the distance L from the side DE to the front expansion section AB of the two throats1Is the extension distance H from A' to side AB1100% -150% of the total throat diameter, and the distance L from the edge DE to the front expansion section AB of the two throats1Not less than 95% of a throat height AA'; (b) edge EF is parallel to BC, and distance L from edge EF to front convergence section BC of two throats2Is the extension distance H from A' to side AB1100% -150% of the total length of the throat, and the distance L from the edge EF to the front convergence section BC of the two throats2Not less than 75% -120% of the height CC' of the second throat, and L2＝(85％-120％)L1。
(2) The length of a diagonal line JJ 'of the quadrangle IJKJ' is at least larger than the minimum value of the first throat height AA 'and the second throat height CC', so that the projection of the inner molded surface of the spray pipe on a vertical plane is closed and is uninterrupted, namely, the central cone completely shields backward incident radar waves and the radar waves cannot directly irradiate the turbine blade cascade at the front part of the spray pipe.
Further, the included angles of the four sides of the quadrangle IJKJ' satisfy a certain relationship: i, an acute angle formed by the edge IJ and the horizontal direction is not less than an angle formed by the edge AB and the horizontal direction, namely the acute angle formed by the edge IJ and the horizontal direction is not less than an expansion angle of an expansion and convergence section at the front part of the two throats; II, an acute angle formed by the side JK and the horizontal direction is not smaller than an angle formed by the side BC and the horizontal direction, namely the acute angle formed by the side JK and the horizontal direction is not smaller than a convergence angle of the expansion and convergence section at the front part of the two throats; III, the intersection point of the extension line of the side IJ, the section AA ' of the throat and the extension line thereof is positioned below the point A ', and the highest intersection point is not beyond the point A '; IV, the intersection point of the extension line of the side JK, the section CC ' of the two throats and the extension line thereof is below the point C ' and is not beyond the point C ' at most. The edges IJ and J' K also need to satisfy similar requirements, and are not described herein. Particularly, the design of the edges IJ and J' I has great influence on the vector performance of the vector nozzle, if the design is not proper, the vector performance of the nozzle after the central cone is added is reduced to 10% -20% of the vector performance of the nozzle without the central cone, and in an extreme case, the vector function of the nozzle is threatened to disappear; on the contrary, if the design is proper, the vectoring performance of the nozzle with the added central cone can be recovered to 70% -80% of the performance of the nozzle without the central cone, and the daily use requirement can be met.
Further, the quadrangle IJKJ 'is rounded at least at < J and < J'. The quadrangle IJKJ 'rounded at the positions of & lt J' still meets the requirements of closed and uninterrupted projection of the inner molded surface of the spray pipe on a vertical plane, so that the central cone completely shields backward incident radar waves and the radar waves cannot directly irradiate to the turbine blade cascade at the front part of the spray pipe. The above design steps can be repeated to complete the design of the quadrilateral IJKJ'. Generally, the quadrilateral IJKJ ' is rounded at ≤ J and ≤ J ' with a radius not less than 10% of a throat height AA ' to reduce flow loss due to sudden steering.
Furthermore, the channel formed by the front convergent sections of the two throats and the central cone cannot be an expansion channel, namely the outlet area of the channel formed by the JK and the BC is not larger than the inlet area, so that the radar waves are prevented from being reflected out of the nozzle due to the dihedral angle effect after being emitted into the nozzle from the rear. The channels formed by J ' K and B ' C ' are the same.
Furthermore, according to whether the central cone can move or not, the central cone is divided into a central cone adjustable type and a central cone non-adjustable type. The adjustable central cone can move back and forth along the central line DF to realize the adjustment of the area of the two throats, enlarge the using envelope of the nozzle and increase the flow stability. For the throat offset type pneumatic thrust vectoring nozzle with the adjustable central cone and the inward S-shaped bend, the working envelope and the design working point of the nozzle are determined firstly. After the working envelope and the design point are determined, the design of the central cone is carried out, and the design of the central cone is as small as possible besides meeting the geometric constraint so as to reduce the blocking effect on the airflow in the spray pipe. The adjusting process comprises the following steps: in the maximum operating condition of the nozzle (i.e. the operating drop pressure ratio NPR is the highest), the central cone is in the most forward position in the quadrilateral DEFE'; along with the gradual reduction of the working pressure drop ratio of the spray pipe, the central cone gradually moves backwards, the minimum flow area of the flow passage in the spray pipe is changed from the position of the first throat to a passage which is clamped by the central cone and the front convergence section of the second throat, namely the maximum distance of the backward movement of the central cone is 15-35% of the length of the concave cavity; the position of the central cone is at the end when the lowest working pressure drop ratio of the spray pipe is reached, at the moment, the central cone cannot be contacted with the front convergent section of the two throats, and the rear sharp point of the central cone cannot protrude out of the sections of the two throats. By moving the central cone back and forth, the adjustment of changing the geometric area of the two throat outlets by 0-100% of the area of the outlet of the spray pipe can be realized theoretically, and the requirement of wide-envelope work of the spray pipe is met. Particularly for low working drop ratio (NPR is less than or equal to 3), the invention can effectively improve the flow stability.
In order to further improve the radar stealth performance of the rear part of the spray pipe, the rear body molded surfaces CL and C 'L' need to be optimally designed. The rear body profiles CL and C 'L' should be as planar as possible, taking into account the direction of the radar reflection, the angles between them and the horizontal plane being α and β, respectively. For most aircraft, α ═ β; in order to control the reflection direction and reduce the rear fuselage resistance, the smaller the alpha and beta are within the range of geometric allowance, the better the alpha and beta are; typically, α and β range from 30 ° to 60 °. The change of alpha and beta has little influence on the performance in the spray pipe, only changes the rear body resistance and the radar reflection performance of the aircraft, and the specific value of the change is combined with the overall design of the aircraft.
For the three-dimensional axisymmetric throat offset type pneumatic vectoring nozzle with the inner S-shaped bend, the internal structure of the three-dimensional axisymmetric throat offset type pneumatic vectoring nozzle is consistent with that of the two-dimensional inner S-shaped bend throat offset type pneumatic vectoring nozzle, and the design method is basically consistent. But the rear body profile needs to be designed comprehensively according to the characteristics of the rear body of the aircraft and keeps an approximate plane, and the rear body cannot be simply rotated. The adjustment rule of the adjustable type of the central cone is consistent with the foregoing description, and will not be described herein.
Furthermore, high-temperature-resistant wave-absorbing coatings are coated inside the front expansion and convergence sections of the central cone and the second throat of the spray pipe, so that the backward radar stealth performance of the spray pipe is further improved.
The thrust vector adjusting method of the nozzle is consistent with that of the conventional throat offset type pneumatic vectoring nozzle, and is not described herein again.
Examples
The calculation is carried out on the throat offset type pneumatic thrust vectoring nozzle with the inner S-shaped bend in the typical configuration and the control method thereof.
FIG. 5 is a graph showing thrust vector angle versus operating drop ratio for the three configurations of nozzle of FIG. 4. Wherein curve a corresponds to the central cone configuration of the solid line in fig. 4, curve B corresponds to the central cone configuration of the dashed line in fig. 4, and curve C corresponds to the nozzle configuration of fig. 4 without the central cone.
Thus, it can be seen that: the solid line central cone is greatly different from the dotted line central cone in the head line profile, and the influence on the nozzle performance is obvious. The thrust vector angle performance of the dotted line central cone is the worst, after the molded line of the nozzle head is optimized, the thrust vector angle performance is obviously improved to 65% of the thrust vector angle performance of the non-central cone, and the thrust vector angle performance can be further improved after the optimization is carried out.
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. The throat offset pneumatic vectoring nozzle with the inner S-shaped bend is characterized in that the inner channel of the throat offset pneumatic vectoring nozzle comprises a nozzle inlet (1), an equal straight section (2), a throat front convergence section (3), a throat (4), two throat front expansion sections (6), two throat front convergence sections (7) and two throats (9) which are sequentially communicated, a spindle-shaped central cone (5) is arranged in a cavity formed by the two throat front expansion sections (6) and the two throat front convergence sections (7), and the cavity of the throat offset pneumatic vectoring nozzle is divided into two S-shaped bends through the central cone (5);
the throat offset type pneumatic vector nozzle comprises a binary configuration, and the binary configuration is formed by stretching molded lines which are symmetrical up and down;
the reference molded lines of the central cone (5) comprise IJ, JK, IJ 'and J' K, and the IJ, the IJ 'and the JK' are symmetrical along a central line IK; the inner molded lines of the concave cavity comprise upper molded lines AB and BC and lower molded lines A 'B' and B 'C' which are relatively symmetric;
the reference profile of the central cone (5) meets the following conditions: (1) the quadrangle IJKJ ' is positioned in the quadrangle DEFE ', and the quadrangle DEFE ' is still a quadrangle which is symmetrical up and down along the central line IK in the cavity, namely DE and D E ', EF and E ' F are symmetrical along the central line IK, and the point D, F is positioned on the extension line of the central line IK; (2) the length of the diagonal line JJ 'of the quadrangle IJKJ' is greater than the minimum value of the height of the first throat AA 'and the height of the second throat CC';
wherein, quadrilateral DEFE' satisfies the following conditions: a. the edge DE is parallel to the edge AB and the distance L from the edge DE to the edge AB1Is the distance H from A' to the extension line of the profile AB1100% -150% of the total distance of the edge DE to the edge AB, and simultaneously satisfies the distance L from the edge DE to the edge AB1Not less than 95% of the height of a throat AA'; b. edge EF is parallel to BC, and the distance L from edge EF to BC2Is the distance H from A' to the extension line of the profile AB1100% -150% of the total weight of the edge, and simultaneously satisfies the distance L from the edge EF to the edge BC2Not less than 75% of the height of the second throat CC', and L2=（85%-120%）L1。
2. The throat offset aerodynamic vectoring nozzle according to claim 1, characterised in that the reference profile IJKJ' of the central cone (5) also satisfies the following condition: i, an acute angle formed by the molded line IJ and the horizontal direction is not smaller than an angle formed by the molded line AB and the horizontal direction, namely the acute angle formed by the molded line IJ and the horizontal direction is not smaller than an expansion angle of the front expansion section of the two throats; II, an acute angle formed by the molded line JK and the horizontal direction is not smaller than an angle formed by the molded line BC and the horizontal direction, namely the acute angle formed by the molded line JK and the horizontal direction is not smaller than a convergence angle of the front convergence section of the two throats; III, the intersection point of the extension line of the molded line IJ and a throat AA ' or the extension line thereof is positioned below the point A ' or the point A '; IV, the intersection point of the extension line of the molded line JK and the two throat passages CC ' or the extension lines thereof is positioned below the point C ' or the point C '.
3. The throat offset pneumatic vectoring nozzle with internal S bend according to claim 1, characterized in that the molded line quadrangle IJKJ 'of the central cone (5) is rounded at least at & lt J and & lt J', and the rounding radius of the quadrangle IJKJ 'at & lt J' and & lt J 'is not less than 10% of the height of a throat AA'.
4. The offset throat aerodynamic vectoring nozzle of claim 1 wherein the exit area of the channel formed by JK and BC is no greater than the entrance area.
5. The throat offset aerodynamic vectoring nozzle according to claim 1, characterised in that the centre cone (5) is movable back and forth along the centre line DF to effect adjustment of the two throat areas by: at the highest operating drop pressure ratio NPR of the nozzle, the central cone (5) is at the most forward position in the quadrilateral DEFE'; along with the gradual reduction of the working pressure drop ratio of the spray pipe, the central cone (5) gradually moves backwards, the minimum flow area of the flow channel in the spray pipe is changed from the position of the first throat (4) to a channel which is clamped by the central cone (5) and the front convergence section of the two throats, and the maximum distance of the backward movement of the central cone (5) is 15-35% of the length of the concave cavity.
6. The throat offset aerodynamic vectoring nozzle with an inside S-bend according to claim 1, characterised in that the nozzle rear body outer profile (8) of the throat offset aerodynamic vectoring nozzle comprises an upper profile CL and a lower profile C 'L' which are included with the horizontal plane by an angle α and β, respectively, and the value of α and β is in the range of 30 ° to 60 °.
7. The throat offset aerodynamic vectoring nozzle with an inside S-bend according to claim 1, characterised in that the outside of the central cone (5) and the inside of the cavity are coated with a high temperature resistant absorbing coating.
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CN112177794B (en) * 2020-08-21 2022-01-04 南京航空航天大学 Throat offset type pneumatic vectoring nozzle and design method thereof
CN114017203B (en) * 2021-11-19 2023-12-19 中国航发沈阳发动机研究所 Jet pipe and airplane rear body slit exhaust cooling device
CN115653779A (en) * 2022-10-13 2023-01-31 中国航发四川燃气涡轮研究院 Multi-shaft pneumatic thrust vectoring nozzle and multi-shaft thrust adjusting method

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