CN103150423B - Rotational symmetry becomes Mach number nozzle and wall defining method thereof continuously - Google Patents

Abstract

The invention discloses a kind of rotational symmetry and become Mach number nozzle and wall defining method thereof continuously.The method comprises: according to nozzle structure designing requirement, determines rotation, known wall curve, wall curve bored by the plug matched with this known wall curve and the relation curve of Sai Zhui mechanism precession distance and Mach number; Wall curve to be asked corresponding when utilizing method of characteristic to determine that Sai Zhui mechanism is in current location according to Sai Zhui mechanism precession distance and the relation curve of Mach number; Change the position of Sai Zhui mechanism on rotation, progressively determine each section of wall curve to be asked; The wall that wall curve and each section of wall curve determination rotational symmetry to be asked become Mach number nozzle is continuously bored according to known wall curve, the plug that matches with this known wall curve.The rotational symmetry that defining method of the present invention is determined becomes the flow field unevenness of Mach number nozzle continuously lower than 1%, and improve an order of magnitude than traditional technology, the susceptibility of jet pipe Mach number to precession distance is controlled.

Description

Rotational symmetry becomes Mach number nozzle and wall defining method thereof continuously

Technical field

The present invention relates to supersonic nozzle design field, become Mach number nozzle and wall defining method thereof continuously in particular to a kind of rotational symmetry.

Background technology

Supersonic speed/hypersonic nozzle is widely used in the equipment such as high-speed aircraft, rocket, supersonic wind tunnel, high-energy laser, injection vacuum pump, and the performance of nozzle flow field product confrontation equipment has important impact.Obtain suitable jet pipe wall surface curve by certain designing technique, can greatly improve nozzle flow field quality, improve equipment performance, save reasearch funds.Supersonic nozzle is generally made up of contraction section and expansion segment, under certain pressure drives, gas accelerates gradually at contraction section, and reaches the velocity of sound at peri-laryngeal, then continue to accelerate at expansion segment, until at the supersonic flow going out Mach number required for interruption-forming and the distribution of flow direction angle.

Along with the dynamic (dynamical) high speed development of Modern air and widespread use, become Mach number nozzle continuously and there is more and more important application prospect.Particularly in wind-tunnel field, be furnished with become continuously Mach number nozzle wind-tunnel can simulated flight device accelerates, slow down, the state such as to cruise, once experiment is equivalent to traditional single Mach number nozzle and tests for tens times even up to a hundred times, and closer to the flight environment of vehicle of reality.But because High Mach number wind-tunnel can only adopt plug nozzle configuration could realize becoming Mach number, corresponding flow field quality cannot ensure, exit Mach number maximum relative error can reach 20% ~ 30%.

A kind of plug bevel-type Nozzle Design method is proposed in prior art, this jet pipe is made up of multiple inner nozzle, plug cone, and inner nozzle is axially symmetric structure, and plug cone is designed to tiles curved surface, inner nozzle can be divided into converging portion, throat, expansion segment, and inner nozzle and plug cone are integrated design.

(Wu Ronglin, Wang Zhenyu write monograph " wind-tunnel design concept ", publishing house of Beijing Aeronaution College, 1985) give a kind of centre-block type jet pipe, this jet pipe is arranged in the movable of the slide block of contraction section by adjustment, form the throat section that size is different, and make slide block and outer wall jointly form different jet pipe curves.

Due to the requirement that stream field quality is very not high, rotational symmetry becomes in Mach number nozzle experimental study in the past and engineer applied does not have very urgent demand, but along with the development of aeronautical and space technology, existing designing technique is difficult to engineering demands.In prior art there is following problems in existing rotational symmetry change Mach number nozzle:

1, the relational expression only by flow and Mach number retrains nozzle throat curve and plug cone curve, does not consider two dimension and the three-dimensional feature of flowing;

2, wave absorption is not considered in Plug contour design, and cause exit flow field quality very poor, even Mach number unevenness is higher than more than 30%, very large to the Accuracy of experimental data.

Summary of the invention

The present invention aims to provide a kind of rotational symmetry and becomes Mach number nozzle and wall defining method thereof continuously, and the flow field uniformity that this rotational symmetry becomes Mach number nozzle is continuously high, exit flow field quality better.

To achieve these goals, according to an aspect of the present invention, provide the wall defining method that a kind of rotational symmetry becomes Mach number nozzle continuously, comprise: according to nozzle structure designing requirement, determine rotation, known wall curve, wall curve bored by the plug matched with this known wall curve and the relation curve of Sai Zhui mechanism precession distance and Mach number; According to the relation curve of Sai Zhui mechanism precession distance with Mach number, wall curve to be asked corresponding when utilizing method of characteristic to determine that Sai Zhui mechanism is in current location; Change the position of Sai Zhui mechanism on rotation, determine each section of wall curve to be asked; The wall that wall curve and each section of wall curve determination rotational symmetry to be asked become Mach number nozzle is continuously bored according to known wall curve, the plug that matches with this known wall curve.

Further, according to nozzle structure designing requirement, determine rotation, known wall curve, wall curve bored by the plug matched with this known wall curve and Sai Zhui mechanism precession distance comprises with the step of the relation curve of Mach number: according to jet pipe work range of Mach numbers, employing method of characteristic determines jet pipe wall surface curve during minimum Mach number, and makes the terminal of plug cone wall curve equal with the coordinate of starting point on rotation of jet pipe wall surface curve; Obtain the minimum Mach number working point of jet pipe, and using this working point as initial Mach number working point.

Further, according to the relation curve of Sai Zhui mechanism precession distance with Mach number, the step of wall curve to be asked corresponding when utilizing method of characteristic to determine that Sai Zhui mechanism is in current location comprises: to be vacillated downwards a dynamic segment distance along axis by plug cone wall curve, make one end away from nozzle exit of known wall curve meet the constraint of die swell ratio to the vertical range of filling in the conical surface, determine the nozzle exit Mach number of Sai Zhui mechanism current position according to initial Mach number working point and Sai Zhui mechanism precession distance with the relation curve of Mach number; According to known wall curve and current nozzle exit Mach number, method of characteristic is utilized to determine to export characteristic curve; According to known wall curve and exporting features line, method of characteristic is utilized to determine the backstepping characteristic curve of known wall curve at porch endpoint location; Bore the intersection point of wall curve for starting point with this backstepping characteristic curve and plug, according to the Mach number of this starting point and transonic speed initial value line equation determine transonic speed initial characteristics line by method of characteristic and iterative formula thereof; According to fixed backstepping characteristic curve and transonic speed initial characteristics line, utilize the wall curve to be asked under method of characteristic determination current state, wherein, the one end of wall curve to be asked under current state and being connected mutually away from the end points exported of known wall curve.

Further, after determining the wall curve to be asked under current state, change the position of Sai Zhui mechanism on rotation, determine that each section of wall curve step to be asked comprises: to be vacillated a dynamic segment distance along axis by plug cone downwards, the one end away from nozzle exit of the wall curve to be asked that the last period is determined meets the constraint of die swell ratio to the vertical range of filling in the conical surface, the wall curve formed according to wall curve fixed to be asked and known wall curve and Sai Zhui mechanism precession distance determine the nozzle exit Mach number of Sai Zhui mechanism current position with the relation curve of Mach number, method of characteristic is utilized to determine new exporting features line, the wall curve formed according to wall curve fixed to be asked and known wall curve and new exporting features line, utilize method of characteristic to determine the new backstepping characteristic curve of wall curve in porch of wall curve fixed to be asked and known wall curve composition, bore the intersection point of wall curve for starting point with this new backstepping characteristic curve and plug, according to the Mach number of this starting point and transonic speed initial value line equation determine new transonic speed initial characteristics line by method of characteristic and iterative formula thereof, according to fixed new backstepping characteristic curve and new transonic speed initial characteristics line, utilize the wall curve to be asked under method of characteristic determination current state, according to fixed new backstepping characteristic curve and new transonic speed initial characteristics line, the wall curve to be asked under utilizing method of characteristic to determine new current state, repeat said process successively, until reach most High Mach number, determine respectively wall curve to be asked.

Further, the iterative formula of method of characteristic is:

Wherein, x is horizontal ordinate, and r is ordinate, and θ is local flow direction angle, M is local Mach number and M>1, δ are pattern of flow parameter, for two-dimensional flow δ=0, axial symmetry flow δ=1, r ≠ 0, γ is the specific heat at constant pressure of gas and the specific heat ratio of specific heat at constant volume.

Further, transonic speed initial characteristics line is determined according to following transonic speed initial value line equation:

$x=-\frac{(\mathrm{\γ}+1)a}{8L}{y}^2$

Wherein:

$a={\left[\frac{2}{(\mathrm{\γ}+1)r_t{\mathrm{\ρ}}_t}\right]}^{1/2}L$

L=ρ _t+r _t

ρ _tand r _tbe respectively radius-of-curvature and half height of nozzle throat, γ is the specific heat at constant pressure of gas and the specific heat ratio of specific heat at constant volume.

Further, method of characteristic comprises to be estimated step and corrects step, corrects step and corrects according to the result estimating step.

According to a further aspect in the invention, provide a kind of rotational symmetry and become Mach number nozzle continuously, the wall defining method that the wall that rotational symmetry becomes Mach number nozzle continuously becomes Mach number nozzle continuously by above-mentioned rotational symmetry is determined.

In accordance with a further aspect of the present invention, provide a kind of rotational symmetry and become Mach number nozzle continuously, comprise known plug cone wall, known wall and connection plug cone wall and the wall to be asked of known wall, wherein, wall to be asked utilizes method of characteristic progressively to determine according to Sai Zhui mechanism precession distance with the relation curve of Mach number.

Apply technical scheme of the present invention, rotational symmetry becomes the wall of Mach number nozzle continuously according to nozzle structure designing requirement, determines rotation, known wall curve, wall curve bored by the plug matched with this known wall curve and the relation curve of Sai Zhui mechanism precession distance and Mach number; Wall curve to be asked corresponding when utilizing method of characteristic to determine that Sai Zhui mechanism is in current location according to Sai Zhui mechanism precession distance and the relation curve of Mach number; Change the position of Sai Zhui mechanism on rotation, progressively determine each section of wall curve to be asked; The wall that wall curve and each section of wall curve determination rotational symmetry to be asked become Mach number nozzle is continuously bored according to known wall curve, the plug that matches with this known wall curve.The direct precession distance of given Sai Zhui mechanism of this method and the relation curve of Mach number, instead of verify correlation curve afterwards, simplify computation process, wall curve under adopting method of characteristic to determine each Mach number, ensure that the position relationship of nozzle exit Mach number and Sai Zhui mechanism meets given relation curve, the rotational symmetry that defining method of the present invention is determined simultaneously becomes the flow field unevenness of Mach number nozzle continuously lower than 1%, improve an order of magnitude than traditional technology, the susceptibility of jet pipe Mach number to precession distance is controlled.

Accompanying drawing explanation

The accompanying drawing forming a part of the present invention is used to provide a further understanding of the present invention, and schematic description and description of the present invention, for explaining the present invention, does not form inappropriate limitation of the present invention.In the accompanying drawings:

Fig. 1 shows the schematic diagram becoming the known wall curve of the wall defining method of Mach number nozzle, axis and plug cone wall curve according to rotational symmetry of the present invention continuously;

Fig. 2 shows the schematic diagram of the first paragraph wall curve to be asked becoming the wall defining method formation of Mach number nozzle according to rotational symmetry of the present invention continuously;

Fig. 3 shows the schematic diagram of the wall defining method formation second segment wall curve to be asked becoming Mach number nozzle according to rotational symmetry of the present invention continuously;

Fig. 4 shows the close-up schematic view in the M portion becoming the wall defining method formation second segment wall curve to be asked of Mach number nozzle according to rotational symmetry of the present invention continuously; And

Fig. 5 shows the schematic diagram of the solution procedure becoming the characteristic strips equation of the wall defining method of Mach number nozzle according to rotational symmetry of the present invention continuously.

Embodiment

Hereinafter also describe the present invention in detail with reference to accompanying drawing in conjunction with the embodiments.It should be noted that, when not conflicting, the embodiment in the application and the feature in embodiment can combine mutually.

In the present invention, the Mach number of supersonic speed section is greater than 1.2, and the Mach number of subsonic speed section is less than 0.8, and transonic speed the Mach number of section is between 0.8 to 1.2.

According to embodiments of the invention, the wall that rotational symmetry becomes Mach number nozzle is continuously determined by the following method.

First, according to nozzle structure designing requirement, determine rotation, known wall curve 1-2, wall curve 3-4 bored by the plug matched with the bent 1-2 line of this known wall and the relation curve X-Ma of Sai Zhui mechanism precession distance and Mach number.Fig. 1 shows known wall curve 1-2, plug cone wall curve 3-4 and rotation.Then, according to jet pipe work range of Mach numbers, employing method of characteristic determines jet pipe wall surface curve during minimum Mach number, the known wall curve 1-2 namely shown in Fig. 1; And according to the designing requirement of plug wimble structure, determine to fill in cone wall curve 3-4 and make the terminal 3 of plug cone wall curve 3-4 equal with the coordinate of starting point 2 on rotation of jet pipe wall surface curve 1-2, when both are equal, obtain the minimum Mach number working point of jet pipe, and using this working point as initial Mach number working point.

As shown in Figure 2, according to the relation curve X-Ma of Sai Zhui mechanism precession distance with Mach number, wall curve 2-7 to be asked corresponding when utilizing method of characteristic to determine that Sai Zhui mechanism is in current location.The steps include: first, plug cone wall curve 3-4 axis to be vacillated downwards a dynamic segment distance, ensure that the end points 2 away from nozzle exit of known wall curve meets the constraint of die swell ratio to the vertical range of filling in the conical surface, determine the nozzle exit Mach number of Sai Zhui mechanism current position according to initial Mach number working point and Sai Zhui mechanism precession distance with the relation curve X-Ma of Mach number; Secondly, method of characteristic is utilized to determine outlet characteristic curve 1-5 according to known wall curve 1-2 and current nozzle exit Mach number; Again, according to known wall curve 1-2 and exporting features line 1-5, utilize method of characteristic to determine the backstepping characteristic curve 2-6 of known wall curve 1-2 at porch end points 2, wherein, known wall curve 1-2 bores wall curve 3-4 at the backstepping characteristic curve 2-6 of the end points 2 of porch with plug and meets at a little 6; Again, the intersection point 6 of boring wall curve 3-4 with this backstepping characteristic curve 2-6 and plug, for starting point, according to the Mach number of this starting point 6 and transonic speed initial value line equation, obtains transonic speed initial characteristics line 6-7 by method of characteristic and iterative formula thereof; Finally, according to fixed backstepping characteristic curve 2-6 and transonic speed initial characteristics line 6-7, utilize the wall curve 2-7 to be asked under method of characteristic determination current state, wherein, the one end of wall curve 2-7 to be asked under current state and being connected mutually away from the end points 2 exported of known wall curve 1-2.

As shown in Figure 3 and Figure 4, after determining first paragraph wall curve to be asked, again plug cone wall curve 3-4 axis to be vacillated downwards dynamic a bit of distance, the end points 7 away from described nozzle exit of first paragraph wall to be asked curve is made to meet the constraint of die swell ratio to the vertical range of filling in the conical surface, also namely 3 '-4 is moved to ', displacement is shorter, and its precision is higher.The curve 1-7 formed according to first paragraph wall to be asked curve 2-7 and known wall curve 1-2 and nozzle exit point 1 place Mach number, utilize characteristic curve, determine new initial characteristics line 1-5 '; According to fixed wall curve 1-7 and exporting features line 1-5 ', method of characteristic is utilized to determine the backstepping characteristic curve 7-8 of fixed wall curve 1-7 at porch end points 7, wherein, determined that wall curve 1-7 bores wall curve 3 '-4 at the backstepping characteristic curve 7-8 of the end points 7 of porch with plug ' meet at a little 8; Again, bore wall curve 3 '-4 with this backstepping characteristic curve 7-8 and plug ' intersection point 8 for starting point, according to the Mach number of this starting point 6 and transonic speed initial value line equation, determine transonic speed initial characteristics line 8-9 by method of characteristic and iterative formula thereof; Finally, according to fixed backstepping characteristic curve 7-8 and transonic speed initial characteristics line 8-9, utilize the wall curve 7-9 to be asked under method of characteristic determination current state, wherein, the one end of wall curve 7-9 to be asked under current state and being connected mutually away from the end points 7 exported of fixed wall curve 1-7.

Repeat the process of Fig. 3 and Fig. 4 successively, until reach most High Mach number, determine respectively wall curve to be asked.The wall that wall curve 3-4 and each section of wall curve determination rotational symmetry to be asked become Mach number nozzle is continuously bored according to known wall curve 1-2, the plug that matches with this known wall curve 1-2.

The iterative formula of method of characteristic is:

Wherein, x is horizontal ordinate, and Δ x is change numerical value on the horizontal scale, r is ordinate, Δ r is change numerical value on the vertical scale, and θ is local flow direction angle, and Δ θ is local flow direction angle change numerical value, M is local Mach number and M>1, Δ M is local Mach number change numerical value, and δ is pattern of flow parameter, for two-dimensional flow δ=0, axial symmetry flow δ=1, r ≠ 0.In the present embodiment, owing to being ultrasonic nonuniform flow nozzle, when it is two-dimensional flow, select δ=0, when it flows for three-dimensional asymmetric, δ and r determines according to actual conditions.

Solve the process of a characteristic curve unit as shown in Figure 5.

Then determined the initial characteristics line sent from throat by transonic speed initial value line equation, shown in Figure 3, this transonic speed initial value line equation be:

$x=-\frac{(\mathrm{\γ}+1)\mathrm{\α}}{8L}{y}^2$

Wherein:

$\mathrm{\α}={\left[\frac{2}{(\mathrm{\γ}+1)r_t{\mathrm{\ρ}}_t}\right]}^{1/2}L$

L=ρ _t+r _t

ρ _tand r _tbe respectively radius-of-curvature and half height of nozzle throat.

Then basis transonic speed initial value line and symmetric condition, obtains initial characteristics line by method of characteristic iteration.

The process solving a characteristic curve unit is as follows:

Suppose two point (x on known curve ₁, r ₁, M ₁, θ ₁), (x ₂, r ₂, M ₂, θ ₂), need to solve thirdly (x ₃, r ₃, M ₃, θ ₃) time, the process shown in Fig. 5 can be utilized to solve.

In solution procedure, first according to estimating step to thirdly solving, then correcting solving value, obtaining the coordinate thirdly after correcting, Mach number and flow direction angle.

Estimate step to comprise:

First solve (x ₃, r ₃),

μ ₁＝sin ^-1(1M ₁)

μ ₂＝sin ^-1(1/M ₂)

h ₁=tan[θ ₁+μ ₁]

h ₂=tan[θ ₂-μ ₂]

Have according to difference equation:

r ₃-r ₁=h ₁(x ₃-x ₁)

r ₃-r ₂=h ₂(x ₃-x ₂)

Two formulas are subtracted each other and can be obtained:

r ₁-r ₂={h ₂-h ₁}x ₃+x ₁h ₁-x ₂h ₂

Try to achieve coordinate thirdly

$\left\{\begin{array}{c}{x}_3=\frac{(r_1-r_2)-(x_1{h}_1-x_2{h}_2)}{h_2-h_1}\\ r_3=h_1(x_3-x_1)+r_1\end{array}\right.---\left(1\right)$

Solve compatibility relation formula below:

Order:

$g_1=\frac{{({M_1}^2-1)}^{1/2}}{1+(\mathrm{\γ}-1){M_1}^2/2}\frac{1}{M_1}$

$g_2=\frac{{({M_2}^2-1)}^{1/2}}{1+(\mathrm{\γ}-1){M_2}^2/2}\frac{1}{M_2}$

$f_1=\mathrm{\δ}\frac{\tan \mathrm{\θ}}{{(M^2-1)}^{1/2}\tan \mathrm{\θ}+1}\frac{r_3-r_1}{r_1}$

$f_2=\mathrm{\δ}\frac{\tan \mathrm{\θ}}{{(M^2-1)}^{1/2}\tan \mathrm{\θ}+1}\frac{r_3-r_2}{r_2}$

Then have:

g ₁(M ₃-M ₁)-(θ ₃-θ ₁)-f ₁=0

g ₂(M ₃-M ₂)+(θ ₃-θ ₂)-f ₂=0

Thus obtain Mach number and the flow direction angle at thirdly position place:

$M_3=\frac{f_1-{\mathrm{\θ}}_1+g_1{M}_1+f_2+{\mathrm{\θ}}_2+g_2{M}_2}{g_1+g_2}$

θ ₃=g ₁(M ₃-M ₁)+θ ₁-f ₁

μ ₃=sin ^-1(1M ₃)

In above-mentioned formula, M ₁be the Mach number at first position place, μ ₁be the Mach angle at first position place, θ ₁be the flow direction angle at first position place, x ₁be the horizontal ordinate at first position place, r ₁be the ordinate at first position place, γ is the specific heat at constant pressure of gas and the specific heat ratio of specific heat at constant volume, and M is local Mach number and M>1, δ are pattern of flow parameter, for two-dimensional flow δ=0, and Three-dimensional Axisymmetric flowing δ=1, r ≠ 0.

M ₂for the Mach number at second point position place, μ ₂for the Mach angle at second point position place, θ ₂for the flow direction angle at second point position place, x ₂for the horizontal ordinate at second point position place, r ₂for the ordinate at second point position place.

M ₃for the Mach number at thirdly position place, μ ₃for the Mach angle at thirdly position place, θ ₃for the flow direction angle at thirdly position place, x ₃for the horizontal ordinate at thirdly position place, r ₃for the ordinate at thirdly position place.

Estimate in step solve thirdly position place coordinate, after Mach number and flow direction angle, the coefficient of equation or parameter are averaged and repeat to estimate the computation process of step, Mach number thirdly and flow direction angle are corrected.This parameter or coefficient mean value solve by the Mach number thirdly of trying to achieve and flow direction angle, order

${M_1}^{\′}=\frac{(M_1+M_3)}{2}$

${M_2}^{\′}=\frac{(M_1+M_3)}{2}$

Wherein M ₁' be first correct after Mach number mean value, M ₂' for second point correct after Mach number mean value, then by M ₁' and M ₂' value substitute into and estimate in step and proceed to solve, until correction of a final proof walk the thirdly Mach number of trying to achieve and estimates the thirdly Mach number M tried to achieve in step ₃location of equal, the final Mach number after the Mach 2 ship correction at thirdly present position place now.In like manner, thirdly the flow direction angle at position place also can obtain final flow direction angle by correcting step.

According to embodiments of the invention, provide a kind of rotational symmetry and become Mach number nozzle continuously, comprise known plug cone wall, known wall and the wall to be asked being connected known plug cone wall and known wall, wherein, wall to be asked utilizes method of characteristic progressively to determine according to Sai Zhui mechanism precession distance with the relation curve of Mach number.

From above description, can find out, the above embodiments of the present invention achieve following technique effect: rotational symmetry becomes the wall of Mach number nozzle continuously according to nozzle structure designing requirement, determine rotation, known wall curve, wall curve bored by the plug matched with this known wall curve and the relation curve of Sai Zhui mechanism precession distance and Mach number; Wall curve to be asked corresponding when utilizing method of characteristic to determine that Sai Zhui mechanism is in current location according to Sai Zhui mechanism precession distance and the relation curve of Mach number; Change the position of Sai Zhui mechanism on rotation, progressively determine each section of wall curve to be asked; The wall that wall curve and each section of wall curve determination rotational symmetry to be asked become Mach number nozzle is continuously bored according to known wall curve, the plug that matches with this known wall curve.The direct precession distance of given Sai Zhui mechanism of this method and the relation curve of Mach number, instead of verify correlation curve afterwards, simplify computation process, wall curve under adopting method of characteristic to determine each Mach number, ensure that the position relationship of nozzle exit Mach number and Sai Zhui mechanism meets given relation curve, the rotational symmetry that defining method of the present invention is determined simultaneously becomes Mach number nozzle flow field unevenness continuously lower than 1%, improve an order of magnitude than traditional technology, the susceptibility of jet pipe Mach number to precession distance is controlled.

The foregoing is only the preferred embodiments of the present invention, be not limited to the present invention, for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (6)

1. rotational symmetry becomes a wall defining method for Mach number nozzle continuously, it is characterized in that, comprising:

According to nozzle structure designing requirement, determine rotation, known wall curve, wall curve bored by the plug matched with this known wall curve and the relation curve of Sai Zhui mechanism precession distance and Mach number;

Wherein, specifically comprise: according to jet pipe work range of Mach numbers, employing method of characteristic determines jet pipe wall surface curve during minimum Mach number, and makes the terminal of described plug cone wall curve equal with the coordinate of starting point on rotation of described jet pipe wall surface curve; Obtain the minimum Mach number working point of jet pipe, and using this working point as initial Mach number working point;

According to the relation curve of described Sai Zhui mechanism precession distance with Mach number, wall curve to be asked corresponding when utilizing described method of characteristic to determine that described Sai Zhui mechanism is in current location;

Wherein, specifically comprise: described plug cone wall curve to be vacillated downwards a dynamic segment distance along described axis, make one end away from nozzle exit of known wall curve meet the constraint of die swell ratio to the vertical range of filling in the conical surface, determine the nozzle exit Mach number of described Sai Zhui mechanism current position according to described initial Mach number working point and described Sai Zhui mechanism precession distance with the relation curve of Mach number; According to described known wall curve and current nozzle exit Mach number, described method of characteristic is utilized to determine to export characteristic curve; According to described known wall curve and described exporting features line, described method of characteristic is utilized to determine the backstepping characteristic curve of described known wall curve at porch endpoint location; With this backstepping characteristic curve and described fill in bore wall curve intersection point for starting point, according to the Mach number of this starting point and transonic speed initial value line equation determine transonic speed initial characteristics line by described method of characteristic and iterative formula thereof; According to fixed described backstepping characteristic curve and transonic speed initial characteristics line, utilize the wall curve to be asked under described method of characteristic determination current state, wherein, the one end of wall curve to be asked under described current state and being connected mutually away from the end points exported of described known wall curve;

Change the position of described Sai Zhui mechanism on rotation, determine each section of wall curve to be asked;

Wall curve is bored and each section of wall curve to be asked determines that described rotational symmetry becomes the wall of Mach number nozzle continuously according to described known wall curve, the described plug of matching with this known wall curve.

2. rotational symmetry according to claim 1 becomes the wall defining method of Mach number nozzle continuously, it is characterized in that, after determining the wall curve to be asked under described current state, the position of the described Sai Zhui mechanism of described change on rotation, determine that each section of wall curve step to be asked comprises:

A, more described plug cone to be vacillated downwards a dynamic segment distance along described axis, the one end away from described nozzle exit of the wall curve to be asked that the last period is determined meets the constraint of described die swell ratio to the vertical range of the described plug conical surface, the wall curve formed according to wall curve fixed to be asked and known wall curve and described Sai Zhui mechanism precession distance determine the nozzle exit Mach number of described Sai Zhui mechanism current position with the relation curve of Mach number, utilize described method of characteristic to determine new exporting features line;

B, according to wall curve fixed to be asked and known wall curve composition wall curve and new exporting features line, utilize described method of characteristic determine described fixed wall curve to be asked and known wall curve composition the new backstepping characteristic curve of wall curve in porch;

C, with this new backstepping characteristic curve and described fill in bore wall curve intersection point for starting point, according to the Mach number of this starting point and transonic speed initial value line equation determine new transonic speed initial characteristics line by described method of characteristic and iterative formula thereof;

D, according to fixed described new backstepping characteristic curve and new transonic speed initial characteristics line, utilize the wall curve to be asked under described method of characteristic determination current state;

E, according to fixed described new backstepping characteristic curve and new transonic speed initial characteristics line, the wall curve to be asked under utilizing described method of characteristic to determine new current state;

Repeat said process A to E successively, until reach most High Mach number, determine each described in wall curve to be asked.

3. rotational symmetry according to claim 1 becomes the wall defining method of Mach number nozzle continuously, it is characterized in that, the iterative formula of described method of characteristic is:

Wherein, x is horizontal ordinate, and r is ordinate, θ is local flow direction angle, and M is local Mach number and M > 1, δ is pattern of flow parameter, for two-dimensional flow δ=0, axial symmetry flow δ=1, r ≠ 0, γ is the specific heat at constant pressure of gas and the specific heat ratio of specific heat at constant volume, Δ x is change numerical value on the horizontal scale, Δ r is change numerical value on the vertical scale, and Δ θ is local flow direction angle change numerical value, and Δ M is local Mach number change numerical value.

4. rotational symmetry according to claim 2 becomes the wall defining method of Mach number nozzle continuously, it is characterized in that, described transonic speed initial characteristics line is determined according to following transonic speed initial value line equation:

$x=-\frac{(\mathrm{\γ}+1)a}{8L}{y}^2$

Wherein:

$a={\[\frac{2}{(\mathrm{\γ}+1)r_t{\mathrm{\ρ}}_t}\]}^{1/2}L$

L＝ρ _t+r _t

ρ _tand r _tbe respectively radius-of-curvature and half height of nozzle throat, γ is the specific heat at constant pressure of gas and the specific heat ratio of specific heat at constant volume, and x is horizontal ordinate, and y is ordinate.

5. rotational symmetry according to any one of claim 1 to 4 becomes the wall defining method of Mach number nozzle continuously, it is characterized in that, described method of characteristic comprises to be estimated step and corrects step, described correct step according to described in estimate step result correct.

6. rotational symmetry becomes a Mach number nozzle continuously, it is characterized in that, the wall defining method that the rotational symmetry of wall according to any one of claim 1 to 5 that described rotational symmetry becomes Mach number nozzle continuously becomes Mach number nozzle is continuously determined.