CN112541231A - Helicopter exhaust pipe shaping spoiler design method - Google Patents

Helicopter exhaust pipe shaping spoiler design method Download PDF

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CN112541231A
CN112541231A CN202011573166.4A CN202011573166A CN112541231A CN 112541231 A CN112541231 A CN 112541231A CN 202011573166 A CN202011573166 A CN 202011573166A CN 112541231 A CN112541231 A CN 112541231A
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exhaust pipe
spoiler
tail
shaping
design
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CN112541231B (en
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陈笑天
吴林波
万兵兵
孙国普
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China Helicopter Research and Development Institute
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China Helicopter Research and Development Institute
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    • G06F—ELECTRIC DIGITAL DATA PROCESSING
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Abstract

The invention belongs to the technical field of helicopter application, and particularly relates to a design method of a shaping spoiler of an exhaust pipe of a helicopter, aiming at the problems that in a gliding flight state, when a wake acts on a vertical tail, the pneumatic environment of the vertical tail is unstable, and an oscillating transverse force is generated, and the tail part is screened. The shaping spoiler configuration meets the requirements of enabling a leeward area of the exhaust pipe to be smoothly transited to the machine body or reducing a leeward surface; the method specifically comprises the following steps of S1: establishing a second-order unsteady display flow field solving model and simulating a gliding state; s2: performing mechanism analysis to determine the reason of tail sieving; s3: determining a reference state for design solution evaluation; s4: forming a design scheme; s5: and verifying the design scheme. The design method of the invention can play the roles of stabilizing the wake flow and inhibiting the tail part from sifting.

Description

Helicopter exhaust pipe shaping spoiler design method
Technical Field
The invention belongs to the technical field of helicopter application, and particularly relates to a design method of a shaping spoiler of a helicopter exhaust pipe.
Background
The helicopter exhaust pipe is used as a key ring of a power cabin system and mainly used for mixing high-temperature gas exhausted by an engine with surrounding air so as to reduce the temperature of tail gas and prevent a fuselage skin from being burnt and corroded. Along with the gradual refinement of the process level and the theoretical analysis, the design requirement of the exhaust pipe is also gradually improved, the appearance, the layout and the direction of the exhaust pipe have important influences on the exhaust efficiency, the temperature and the noise, and the targeted modification design research is made on the aspect of the exhaust pipe of the infrared stealth on the basis of the design thinking of the deviation stealth of the armed helicopter. Since the exhaust of the hot gas from the power compartment is affected by the installation location and the shape of the opening, this is directly related to the exhaust efficiency and the ablation of the skin.
Most of the existing helicopter exhaust pipes of most models are installed at 45 degrees obliquely upwards towards two sides of a fuselage and protrude one section of the fuselage, but the influence on the wake flow passing through the exhaust pipes is obvious. In a specific gliding flight state, the wake will act on the vertical tail to generate an oscillating transverse force, resulting in a tail sifting phenomenon unacceptable to pilots.
Aiming at the problem, the wing-shaped part is additionally arranged at the rear part of the exhaust pipe of the power cabin at the back of the helicopter body in foreign countries and used for at least partially blocking airflow flowing from the exhaust port of the power cabin to the direction of the tail wing, the wing-shaped part of the power cabin is continuously modified by carrying out a vortex wake flow aerodynamic interference wind tunnel test and combining with an aerodynamic simulation analysis technology, and the problem that the falling vortex generated by the exhaust pipe and the main tower reducing seat can move to the two sides of the helicopter body by the additional wing-shaped part is found, so that the adverse effect of the falling vortex on the vertical tail is weakened, the effect of stabilizing and increasing the aerodynamic force of the vertical tail is achieved, and the problem of tail part sieving.
Because airfoil parameter is relevant with specific operating mode, be difficult to form clear and definite design criterion, manufacturing process is complicated and the installation is inconvenient, carries out blast pipe plastic spoiler aerodynamic analysis and design research based on the similar afterbody problem of sieving that this helicopter appears to the realization plays stable wake, suppresses the effect of afterbody sieve.
Disclosure of Invention
The purpose of the invention is as follows: the invention provides a pneumatic analysis and design method of an exhaust pipe shaping spoiler, aiming at solving the problem of tail sifting caused by unstable oscillating transverse force generated by a vertical tail pneumatic environment when a wake acts on the vertical tail in a gliding flight state.
The technical scheme of the invention is as follows: in order to achieve the above object, according to a first aspect of the present invention, a method for designing a shaping spoiler for an exhaust pipe of a helicopter is provided, wherein the shaping spoiler is configured to smoothly transition a leeward region of the exhaust pipe to a fuselage or reduce a leeward surface.
In one possible embodiment, the method specifically comprises the following steps:
s1: establishing a second-order unsteady display flow field solving model and simulating a gliding state;
simplifying and processing a helicopter fuselage model and generating an unstructured grid, establishing a second-order unsteady display flow field solving model, and performing multi-group gliding state simulation;
s2: performing mechanism analysis to determine the reason of tail sieving;
comparing the vertical tail lateral force coefficient C of each group of gliding state by observing each group of vorticity cloud pictures obtained by the gliding state simulation of the step S1CYVertical force coefficient C of horizontal tailPZDetermining the fluctuation amount of the tail part to obtain the reason of the tail part sieving;
s3: determining a reference state for design solution evaluation;
vertical fin lateral force coefficient C of multiple groups of gliding statesCYVertical force coefficient C of horizontal tailPZTaking the coefficient of vertical fin lateral force CCYVertical force coefficient C of horizontal tailPZThe glide state with the maximum fluctuation amount is used as a reference state for evaluating the design scheme;
s4: forming a design scheme;
forming a shaping spoiler configuration design scheme which can enable a leeward area of the exhaust pipe to be smoothly transited to the machine body or reduce a leeward surface; the following scheme 1 or scheme 2 was employed:
scheme 1: the shape of the transition to the thin sheet is connected with the tail beam skin;
scheme 2: a fairing is arranged on the leeward side of the exhaust pipe and is connected with the arc-shaped body covering of the leeward side of the exhaust pipe;
s5: verifying a design scheme;
comparing the design scheme with the vertical fin lateral force coefficient C under the initial conditionCYVertical force coefficient C of horizontal tailPZAt the vertical force coefficient C of the horizontal tailPZUnder the condition that the change does not exceed 10%, if the fluctuation amount of the vertical tail lateral force coefficient is reduced to 1/2, the design scheme is verified to be valid; if not, returning to the step S4 to repeat the scheme design until the verification is valid.
In a possible embodiment, in the step S1, multiple sets of glide states are obtained by determining glide rates corresponding to different forward flight speeds, and an ciem-FLUENT flow field analysis technique is used to perform a glide flight flow field simulation.
In a possible embodiment, in the step S2, the reason for the tail sifting is due to instability of the vertical tail aerodynamic environment caused by the shedding vortex of the tower base, the exhaust pipe and the door slide rail boss.
Preferably, the cause of the tail sifting mainly affects the shedding vortex from the exhaust pipe.
In a possible embodiment, in the step S4, the shaping spoiler in the scheme 1 is in a shape of "stretched Y", and the specific design process is as follows: firstly, determining the tangential position of the upper surface and the lower surface of the shaping spoiler with the ring surface of the exhaust pipe and the joint position of the upper surface and the lower surface of the shaping spoiler with the tail beam section; then determining the contour line, taking the contour line to be consistent with the height of the exhaust pipe protruding out of the surface of the machine body, enabling the upper surface and the lower surface to gradually shrink towards the middle along the longitudinal direction of the machine body, and finally transitioning into thin sheets to be connected with the tail beam section.
In a possible embodiment, in the step S4, the scheme 2 shaped spoiler is in a "compressed Y" shape as a whole, and the specific design process is as follows: firstly, determining the tangential position of the shaping spoiler with the ring surface of the exhaust pipe and the surface of the airframe, adding an additional auxiliary line for obtaining a smooth curved surface with consistent curvature, wherein the initial height is consistent with the height of the exhaust pipe, the height and the span of the longitudinal spoiler of the airframe are gradually reduced, and finally the tangential position of the shaping spoiler with the surface of the airframe is determined.
In one possible embodiment, in the step S4, the shaping spoiler may be made of a metal material.
In a possible embodiment, in the step S4, the shaping spoiler is fixedly connected to the body.
According to a second aspect of the invention, a helicopter is provided, which is characterized by comprising a spoiler designed by the helicopter exhaust pipe shaping spoiler design method.
The invention has the beneficial technical effects that: the invention provides a pneumatic analysis and design method of an exhaust pipe shaping spoiler, which aims at solving the problem of tail sifting caused by unstable vertical tail pneumatic environment and oscillatory transverse force generated when a wake acts on a vertical tail in a gliding flight state. Through modeling and analysis, two design schemes of shaping spoiler configurations which can enable a leeward area of the exhaust pipe to be smoothly transited to the fuselage or reduce a leeward surface are formed;
scheme 1 well flow line is mainly divided into two parts, and the majority is hugging closely and is flowing through the vertical fin, provides stable aerodynamic environment, and the subtotal deviates to the fuselage outside, and the influence to the vertical fin obviously reduces, and different scheme 2 makes the flow line nearly straight through the radome fairing, has reduced the formation of vortex, but undulant while flow through the flow field of vertical fin also weakens, leads to aerodynamic loss. Compared with the vertical tail lateral force coefficients of the two schemes, the aerodynamic force of the scheme 1 is increased by 4.9%, the aerodynamic force of the scheme 2 is reduced by 10%, the fluctuation quantity is obviously reduced, the amplitude of the scheme 1 is reduced to 25%, the amplitude of the scheme 2 is reduced to 39%, and the fluctuation quantity is greatly reduced on the basis that the overall aerodynamic force is not influenced. In sum, the two exhaust pipe shaping spoiler designs can form a more stable flow field environment, are more favorable for the horizontal vertical tails and have more obvious effect on the vertical tails. The two current schemes are simple in design and easy to manufacture, and are suitable for being adopted in various helicopters.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.
The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so that those skilled in the art can understand and read the present invention, and do not limit the conditions for implementing the present invention, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the functions and purposes of the present invention, should still fall within the scope of the present invention.
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a schematic view of the exhaust pipe fairing of embodiment 1 of the present invention in a position relative to the fuselage;
FIG. 3 is a schematic diagram of the shape and key parameters of the exhaust pipe shaping spoiler according to embodiment 1 of FIG. 1;
FIG. 4 is a schematic view of the exhaust duct fairing of embodiment 2 of the present invention in relation to the fuselage;
FIG. 5 is a schematic diagram of the shape and key parameters of the spoiler for shaping the exhaust pipe according to embodiment 2 of FIG. 2;
FIG. 6 shows vertical-tailed lateral force coefficients C of examples 1 and 2 and comparative examplesCYComparing the schematic diagrams;
FIG. 7 shows vertical force coefficients C of the horizontal tails of examples 1 and 2 and comparative examplesPZComparing the schematic diagrams.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the present invention, and the terms "first", "second", "third" are used for descriptive purposes only and are not intended to indicate or imply relative importance; furthermore, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be construed broadly, as they may be fixedly connected, detachably connected, or integrally connected, for example; there may be communication between the interiors of the two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
As shown in fig. 1, according to a first aspect of the present invention, a method for designing a shaping spoiler of a helicopter exhaust pipe is provided, which specifically includes the following steps:
s1: establishing a second-order unsteady display flow field solving model and simulating a gliding state;
establishing a second-order unsteady display flow field solving model by simplifying and processing a fuselage model and generating an unstructured grid; selecting a plurality of groups of gliding states for simulation;
modeling is carried out on the basis of a certain type machine (without a rotor wing and a tail rotor), and 6 groups of different glide calculation states are taken: the forward flight speeds of 60kt, 70kt and 80kt respectively correspond to the downward slip rates of 1500ft/min and 2000ft/min, the corresponding downward slip angles are 13.87 degrees, 11.95 degrees, 10.49 degrees, 18.22 degrees, 15.76 degrees and 13.87 degrees, and the ICEM-FLUENT flow field analysis technology is used for simulating the flow field during downward sliding flight;
s2: and (4) carrying out mechanism analysis: by observing the vorticity nephogram and comparing the lateral force coefficient C of the vertical tails in 6 groups of statesCYVertical force coefficient C of horizontal tailPZDetermining that the tail part sieving is caused by unstable vertical tail pneumatic environment caused by shedding vortexes of a tower seat, an exhaust pipe and a cabin door sliding rail boss, wherein the primary influence is from the shedding vortexes of the exhaust pipe;
the detailed analysis process is as follows, the vortex dragged out by the tower seat, the exhaust pipe and the cabin door sliding rail boss gradually inclines upwards along with the increase of the downward sliding angle by observing a vortex cloud picture and a flow field, wherein the vortex strength behind the cabin door sliding rail is weaker when the downward sliding angle alpha is less than 13.87 degrees, and the vortex is directly acted on the horizontal tail, so that the influence on the aerodynamic force of the vertical tail is smaller; and the vortex behind the sliding rail of the cabin door is stronger when the sliding angle alpha is more than 13.87 degrees, and the aerodynamic force of the horizontal tail and the vertical tail is influenced. In order to further determine the key state of the tail sieving problem, the vertical force coefficient and the horizontal force coefficient of the vertical tail of each state are compared, so that the flow field dynamic environment is illustrated when the vertical tail slides at a high speed, the vertical tail pneumatic environment is more unstable, and the reason of tail sieving is that the falling vortex generated by the exhaust pipe is mainly caused by the influence of the unstable gas of the vertical tail;
s3: determining an evaluation strategy: comparing the vertical and horizontal tail gas power coefficients of 6 groups of states, so that the effect of a subsequent design scheme can be better reflected, and taking the flight state with larger fluctuation quantity, namely the front flight speed of 80kt and the downward sliding rate of 2000ft/min as the reference state of the design scheme evaluation;
to obtain stable pneumatic environment of the horizontal and vertical tails and ensure the vertical force coefficient C of the horizontal tailsPZReduce the vertical fin lateral force coefficient C as much as possible under the stable premiseCYThe wave of the air outlet pipe is shaped and designed aiming at the air outlet pipe so as to reduce the flow separation of the leeward side, two spoiler design schemes are provided, and the gliding state with the forward flying speed of 80kt and the gliding rate of 2000ft/min is selected as the reference state for evaluating the design schemes;
s4: forming a design scheme: aiming at the back wind area of the exhaust pipe, a shaping spoiler scheme 1 or a shaping spoiler scheme 2 capable of smoothly transiting to a machine body or reducing the back wind surface is designed, so that the effect of weakening flow separation of the back subarea of the exhaust pipe so as to avoid unstable pneumatic environment caused by falling vortex is realized; scheme 1: the arc shape of the leeward side of the exhaust pipe is transited to a thin sheet shape to be connected with the tail beam skin; scheme 2: a fairing is added on the leeward side of the exhaust pipe and is connected with the fuselage skin;
example 1
By adopting the scheme 1, as shown in fig. 2, the schematic position diagram of the exhaust pipe shaping spoiler in the scheme 1 of the invention is compared with the position diagram of the airframe; the arc shape of the leeward side of the exhaust pipe is transited to a thin sheet shape to be connected with the tail beam skin;
as shown in fig. 3, it is a schematic diagram corresponding to the shapes and key parameters of the exhaust pipe shaping spoiler in embodiment 1 of scheme 1; in the scheme 1, the shaping spoiler is integrally in a stretched Y shape, and the specific design process is as follows:
firstly, determining the tangent positions of the upper surface and the lower surface of a spoiler with the ring surface of an exhaust pipe and the joint position of the upper surface and the lower surface of the spoiler with a tail beam section, then determining a contour line, taking the contour line consistent with the height of the exhaust pipe protruding out of the surface of a machine body, gradually shrinking the upper surface and the lower surface towards the middle along the longitudinal direction of the machine body, and finally transiting into a thin sheet with the thickness of 5 mm;
taking a curve with the length of 5mm on the intersection line of the tail beam and the transition section of the airplane body
Figure BDA0002861216860000071
And the arc transition area is positioned on the upper surface and the side surface of the tail beam. 1/4 sections of arc lines are taken on the intersection line of the exhaust pipe and the machine body
Figure BDA0002861216860000072
Two end points of the arc are required to be respectively close to the inner side and the rear side of the exhaust pipe, and an isoparametric curve is drawn on the ring surface of the exhaust pipe through two end points C, D
Figure BDA0002861216860000073
As the intersection of the spoiler and the exhaust pipe. Obtained by connecting A, C and B, D by sample lines
Figure BDA0002861216860000074
And
Figure BDA0002861216860000075
and projected on the fuselage
Figure BDA0002861216860000076
And
Figure BDA0002861216860000077
as the intersection of the spoiler and the fuselage transition. Translation
Figure BDA0002861216860000078
To A, BTo obtain
Figure BDA0002861216860000079
And
Figure BDA00028612168600000710
drawing an isoparametric curve of the tail beam section by passing through A, B two points
Figure BDA00028612168600000711
And
Figure BDA00028612168600000712
taking a curve with the length of 445mm on the two curves
Figure BDA00028612168600000713
And
Figure BDA00028612168600000714
as the intersection of the spoiler and the tail beam section. Are connected E, E respectively by sample lines1M and F, F1N obtaining the outer contour line of the spoiler
Figure BDA00028612168600000715
And
Figure BDA00028612168600000716
and finally, filling the upper and lower surfaces of the shaping turbulent flow by using a bridging curved surface to obtain the upper and lower surfaces of the shaping turbulent flow, wherein the whole shaping turbulent flow is in a 'stretching Y' -shape, the upper and lower surfaces are tangent to the annular surface of the exhaust pipe, the height of the upper and lower surfaces is consistent with the height of the surface of the exhaust pipe protruding out of the machine body, the upper and lower surfaces gradually approach to the middle along the longitudinal direction, and finally the upper.
Example 2
With the scheme 2, as shown in fig. 4 and 5, fig. 4 is a schematic position diagram of the exhaust pipe shaping spoiler in the scheme 2 of the invention compared with the fuselage;
FIG. 5 is a schematic diagram of the shape and key parameters of the spoiler for shaping the exhaust pipe according to embodiment 2 of FIG. 2;
the scheme 2 is integrally in a compressed Y shape, and a fairing is added on the leeward side of the exhaust pipe and connected with the fuselage skin; the specific design process is as follows:
firstly, determining the tangent position of the surface of the fuselage and the annular surface of the exhaust pipe, adding an additional auxiliary line for obtaining a smooth curved surface with the same curvature, wherein the initial height is the same as the height of the exhaust pipe, the height and the span of the longitudinal spoiler of the fuselage are gradually reduced, and finally the tangent position of the surface of the fuselage is tangent as shown in fig. 2 and 4;
taking a curve of the width 1/3 length of the exhaust pipe on the intersection line of the tail beam and the transition section of the airplane body
Figure BDA0002861216860000081
As the intersection line of the fairing and the fuselage skin, 1/2 arc segments are taken from the intersection line of the exhaust pipe and the fuselage
Figure BDA0002861216860000082
Two end points are respectively close to the inner side and the outer side of the exhaust pipe, and an isoparametric curve is drawn on the ring surface of the exhaust pipe through c and d
Figure BDA0002861216860000083
As the intersection line of the fairing and the exhaust pipe, a, c, b and d sampling lines are connected
Figure BDA0002861216860000084
Projected onto the surface of the fuselage
Figure BDA0002861216860000085
Figure BDA0002861216860000086
As the intersection of the fairing and the fuselage surface. After the contour line is obtained, the contour line is subdivided and filled by curved surfaces to obtain the smooth shape of the fairing, the whole fairing is in a 'compressed Y' -shape and is tangent to the ring surface of the exhaust pipe, the initial height is consistent with the height of the exhaust pipe, the width and the height are gradually reduced along the longitudinal direction, and finally the fairing is tangent to the surface of the airframe.
Comparative example
The shaping spoiler is not arranged on the exhaust pipe of the helicopter.
S5: design scheme verification: comparing each design scheme with the initial condition of the comparative example without helicopter exhaustVertical fin lateral force coefficient C of shaping spoiler arranged on pipeCYVertical force coefficient C of horizontal tailPZAt the vertical force coefficient C of the horizontal tailPZUnder the condition that the change does not exceed 10%, if the fluctuation amount of the vertical tail lateral force coefficient is reduced to 1/2, the design scheme is verified to be valid; if not, returning to the step S4 to carry out scheme design again until the verification is valid;
observing the flow fields of the example 1, the example 2 and the comparative example, and comparing the vertical tail lateral force coefficient and the horizontal tail vertical force, wherein the average value 515N and the amplitude 97N of the vertical tail lateral force of the comparative example, the average value 536N and the amplitude 46N of the horizontal tail vertical force are compared under the original state without scrambling the flow sheet; the average value 540N and the amplitude 24N of the vertical tail lateral force, the average value 570N and the amplitude 20N of the horizontal tail vertical force of the shaping spoiler design in the embodiment 1 are added; example 2 vertical tail lateral force mean 463N, amplitude 38N, horizontal tail vertical force mean 562N, amplitude 33N with the addition of the flow-cap spoiler design. Therefore, the flow field environment of the horizontal and vertical tails in the first scheme and the second scheme is more stable, the amplitude of stress fluctuation is reduced, the problem of tail sieving in the current gliding state can be effectively solved, and the design is finished.
FIG. 6 shows vertical-tailed lateral force coefficients C of examples 1 and 2 and comparative examplesCYComparing the schematic diagrams;
FIG. 7 shows vertical force coefficients C of the horizontal tails of examples 1 and 2 and comparative examplesPZComparing the schematic diagrams.
As can be seen from the graphs of FIGS. 6 and 7, the vertical-tail lateral force coefficient of the two schemes is compared, the aerodynamic force of the scheme 1 is increased by 4.9%, the aerodynamic force of the scheme 2 is reduced by 10%, the fluctuation amount is obviously reduced, the amplitude of the scheme 1 is reduced to 25%, the amplitude of the scheme 2 is reduced to 39%, and the fluctuation amount is greatly reduced on the basis of not influencing the overall aerodynamic force. And comparing the vertical force coefficients of the horizontal tail of the two schemes, the fluctuation of the force coefficients of the two schemes is slightly reduced, the aerodynamic force is increased, and the horizontal tail force coefficient of the scheme 1 is more stable. In sum, the two exhaust pipe shaping spoiler designs can form a more stable flow field environment, are more favorable for the horizontal vertical tails and have more obvious effect on the vertical tails. The two current schemes are simple in design and easy to manufacture, and can be adopted in various helicopters.
The foregoing is merely a detailed description of the embodiments of the present invention, and some of the conventional techniques are not detailed. The scope of the present invention is not limited thereto, and any changes or substitutions that can be easily made by those skilled in the art within the technical scope of the present invention will be covered by the scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A design method for a shaping spoiler of an exhaust pipe of a helicopter is characterized in that the shaping spoiler is configured to enable a leeward area of the exhaust pipe to be smoothly transited to a fuselage or reduce a leeward surface.
2. The design method of the helicopter exhaust pipe shaping spoiler of claim 1, characterized by comprising the following steps:
s1: establishing a second-order unsteady display flow field solving model and simulating a gliding state;
simplifying and processing a helicopter fuselage model and generating an unstructured grid, establishing a second-order unsteady display flow field solving model, and performing multi-group gliding state simulation;
s2: performing mechanism analysis to determine the reason of tail sieving;
comparing the vertical tail lateral force coefficient C of each group of gliding state by observing each group of vorticity cloud pictures obtained by the gliding state simulation of the step S1CYVertical force coefficient C of horizontal tailPZDetermining the fluctuation amount of the tail part to obtain the reason of the tail part sieving;
s3: determining a reference state for design solution evaluation;
vertical fin lateral force coefficient C of multiple groups of gliding statesCYVertical force coefficient C of horizontal tailPZTaking the coefficient of vertical fin lateral force CCYVertical force coefficient C of horizontal tailPZThe glide state with the maximum fluctuation amount is used as a reference state for evaluating the design scheme;
s4: forming a design scheme;
forming a design scheme of shaping spoiler configuration which can enable a leeward area of the exhaust pipe to be smoothly transited to the fuselage or reduce a leeward area; the following design 1 or design 2 was used:
scheme 1: the shape of the transition to the thin sheet is connected with the tail beam skin;
scheme 2: a fairing is arranged on the leeward side of the exhaust pipe and is connected with the arc-shaped body covering of the leeward side of the exhaust pipe;
s5: verifying a design scheme;
comparing the design scheme with the vertical fin lateral force coefficient C under the initial conditionCYVertical force coefficient C of horizontal tailPZAt the vertical force coefficient C of the horizontal tailPZUnder the condition that the change does not exceed 10%, if the fluctuation amount of the vertical tail lateral force coefficient is reduced to 1/2, the design scheme is verified to be valid; if not, returning to the step S4 to repeat the scheme design until the verification is valid.
3. The method for designing the reshaping spoiler of the exhaust pipe of the helicopter of claim 2, wherein in the step S1, a plurality of groups of glide states are obtained by determining glide rates corresponding to different forward flight speeds, and an ICEM-FLUENT flow field analysis technique is used for simulating the flow field during the glide flight.
4. The method of claim 2, wherein in step S2, the cause of the tail sifting is due to instability of vertical-tailed aerodynamic environment caused by deswirl of tower base, exhaust pipe and cabin door slide rail boss.
5. The design method of the helicopter exhaust pipe shaping spoiler of claim 4, wherein the cause of the tail sifting mainly affects the vortex shedding from the exhaust pipe.
6. The method of claim 2, wherein in step S4, the shaping spoiler in the embodiment 1 is in a shape of "stretched Y", and the specific design process is as follows: firstly, determining the tangential position of the upper surface and the lower surface of the shaping spoiler with the ring surface of the exhaust pipe and the joint position of the upper surface and the lower surface of the shaping spoiler with the tail beam section; then determining the contour line, taking the contour line to be consistent with the height of the exhaust pipe protruding out of the surface of the machine body, enabling the upper surface and the lower surface to gradually shrink towards the middle along the longitudinal direction of the machine body, and finally transitioning into thin sheets to be connected with the tail beam section.
7. The method of claim 2, wherein in step S4, the shaping spoiler of scheme 2 is in a "compressed Y" shape as a whole, and the specific design process is as follows: firstly, determining the tangent position of the exhaust pipe ring surface and the surface of the machine body, adding an additional auxiliary line for obtaining a smooth curved surface with the same curvature, wherein the initial height is the same as the height of the exhaust pipe, the height and the span of the random longitudinal spoiler are gradually reduced, and finally, the tangent position of the random longitudinal spoiler is tangent to the surface of the machine body.
8. The method of claim 2, wherein in step S4, the shaping spoiler is made of metal.
9. The method of claim 2, wherein in step S4, the shaping spoiler is fixedly connected to the fuselage.
10. A helicopter comprising a spoiler designed by the helicopter exhaust pipe shaping spoiler design method according to any one of claims 1 to 9.
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