阅读说明：本技术 一种用于火箭发动机的等水力直径的冷却通道设计方法 (Method for designing equal hydraulic diameter cooling channel for rocket engine ) 是由 李龙 李轩 姚卫 汪球 栗继伟 赵伟 于 2021-03-05 设计创作，主要内容包括：本发明提供一种用于火箭发动机的等水力直径的冷却通道设计方法,根据推力室压力、喷管扩张比和驻留时间要求,计算出各冷却通道的内壁面曲线,内壁厚度；由冷却通道的内壁厚度确定冷却通道底部的高度,进而确定冷却通道底部的沿程型线,根据冷却通道的数量和肋厚确定每个冷却通道截面各处的数据,进而得到冷却通道截面四个侧边的沿程型线；根据前述各计算结果,即可计算确定发动机截面所有点的三维分布,从而可通过三维软件设计得到冷却通道的三维形状。本发明公开的等水力直径冷却通道设计方法,将传统的冷却通道进行优化,通道内压力损失小,结构简单、可靠,轻量化作用明显可以有效的减轻发动机的质量。(The invention provides a method for designing a cooling channel with equal hydraulic diameter for a rocket engine, which comprises the steps of calculating the inner wall surface curve and the inner wall thickness of each cooling channel according to the requirements of the pressure of a thrust chamber, the expansion ratio of a spray pipe and the residence time; determining the height of the bottom of the cooling channel according to the thickness of the inner wall of the cooling channel, further determining the on-way molded lines of the bottom of the cooling channel, and determining data of each cooling channel section according to the number and the rib thickness of the cooling channel, further obtaining the on-way molded lines of four sides of the cooling channel section; according to the calculation results, the three-dimensional distribution of all the points of the section of the engine can be calculated and determined, so that the three-dimensional shape of the cooling channel can be obtained through three-dimensional software design. The design method of the equal hydraulic diameter cooling channel disclosed by the invention optimizes the traditional cooling channel, has small pressure loss in the channel, simple and reliable structure and obvious light weight effect, and can effectively reduce the mass of an engine.)

1. A method for designing a cooling channel with an equal hydraulic diameter for a rocket engine is characterized by comprising the following steps:

step 100, setting cooling channels with fan-shaped cross sections to be distributed around a thrust chamber, and calculating an inner wall surface curve of each cooling channel by adopting a cylindrical coordinate system on the basis of taking the thrust chamber as a circular symmetrical structure according to the pressure of the thrust chamber, the expansion ratio of a spray pipe and the residence time requirement;

step 200, calculating the thickness of the inner wall of the cooling channel according to the thermal protection requirement of the thrust chamber, the heat flow distribution of the inner wall surface and the heat conduction performance of the material by combining the temperature of the inner side wall and the temperature of the outer side wall of the inner wall of the thrust chamber;

step 300, determining the height of the bottom of the cooling channel according to the thickness of the inner wall of the cooling channel, further determining the on-way molded lines of the bottom of the cooling channel, and determining data of each cooling channel section according to the number and the rib thickness of the cooling channel, further obtaining the on-way molded lines of four sides of the cooling channel section;

and step 400, according to the calculation results, calculating and determining the three-dimensional distribution of all points of the section of the engine, so that the three-dimensional shape of the cooling channel can be obtained through three-dimensional software design.

2. The design method according to claim 1,

in step 100, the inner wall surface curve L_inThe calculation formula of (2) is as follows:

L_in＝f_in(r_in,θ,x)

wherein x is an axial coordinate with the throat center as a coordinate origin, r_inIs a curve L of the inner wall surface of the thrust chamber_inOf (c) is used.

3. The design method according to claim 2,

in step 200, the inner wall thickness δ₁The calculation formula of (T, r, θ, x) is as follows:

wherein q is_w(r, theta, x) is heat flow distribution, k (T, r, theta, x) is material heat-conducting property parameter, T_wgInner wall temperature, T, of the inner wall_wfThe inner wall temperature and the outer wall temperature.

4. The design method according to claim 3,

in step 300, the height r of the bottom of the cooling channel₁The calculation formula of (2) is as follows:

r₁＝r_in+δ₁

wherein r is_inThe distance between the inner wall of the thrust chamber and the bottom of the cooling channel.

5. The design method according to claim 4,

in the step 300, the line L along the way of the bottom of the cooling channel₁The calculation formula is as follows:

L₁＝f₁(r₁,0,x)。

6. the design method according to claim 5,

in step 300, the data of the cooling channel cross section includes: bottom arc length, top arc length, both sides height, hydraulic diameter of equal size, cross-sectional area, cross-sectional perimeter, top height and central angle.

7. The design method according to claim 6,

when the number of the cooling channels is n and the thickness of the rib is W,

the bottom arc length s₁(r, θ, x) is:

s₁(r,θ,x)＝2πr₁/n-W

top arc length s₂(r, θ, x) is:

s₂(r,θ,x)＝2πr₂/n-W

the heights H of both sides are:

H＝r₂-r₁

constant hydraulic diameter d_HComprises the following steps:

4A/C＝d_H＝Const

the cross-sectional area A is:

the section perimeter C is:

C＝s₂+s₁+2H

height of the top r₂Comprises the following steps:

central angle theta₁Comprises the following steps:

θ₁＝2π/n-W/r₁。

8. the design method according to claim 7,

in the step 300, the calculation formulas of the on-way molded lines of the four sides of the cooling channel section are respectively as follows:

top contour line L₂Comprises the following steps:

L₂＝f₂(r₂,0,x)

one-side molded line L in width direction of bottom₃Comprises the following steps:

L₃＝f₃(r₁,θ₁/2,x)

one side molded line L of the top in the width direction₄Comprises the following steps:

L₄＝f₄(r₂,θ₁/2,x)

because the height of the outer wall of the thrust chamber is the height of the top of the cooling channel plus the thickness of the outer wall, the height of the outer wall of the thrust chamber is as follows:

r_out＝r₂+δ₂

further obtaining the molded line L of the outdoor wall surface of the thrust_outThe calculation formula is as follows:

L_out＝f_out(r_out,θ,x)。

Technical Field

The invention relates to the field of rockets, in particular to a method for designing a cooling channel with equal hydraulic diameter for a rocket engine.

Background

The pressure of the thrust chamber of the liquid rocket engine is high, the heat flux density of the wall surface of the thrust chamber is high, and the temperature of fuel gas can reach thousands of degrees centigrade, which exceeds the temperature which can be born by common engine materials. However, the wall of the thrust chamber allows much smaller heat flows, and if necessary protection measures are not taken, the temperature of the wall of the thrust chamber is too high under the severe conditions, and the wall of the thrust chamber is even burnt.

In order to carry out thermal protection, a cooling channel is arranged between the inner wall surface and the outer wall surface of the engine, the section of the cooling channel of the rocket engine is changed along with the section of the engine, but the hydraulic diameter of the channel is always kept unchanged. The rocket fuel flows at a high speed in the channel, absorbs heat and heats, and actively cools the engine structure to protect the engine structure from ablation damage.

The cooling channel of the traditional engine is designed into a rectangular groove structure with a uniform section or a simple variable section, and large fluid pressure loss is easily caused.

Disclosure of Invention

The invention aims to provide a design method of an equal hydraulic diameter cooling channel for a rocket engine, and the structural manufacturing can be realized through a 3D printing technology.

Specifically, the invention provides a method for designing a cooling channel with an equal hydraulic diameter for a rocket engine, which comprises the following steps:

step 100, setting cooling channels with fan-shaped cross sections to be distributed around a thrust chamber, and calculating an inner wall surface curve of each cooling channel by adopting a cylindrical coordinate system on the basis of taking the thrust chamber as a circular symmetrical structure according to the pressure of the thrust chamber, the expansion ratio of a spray pipe and the residence time requirement;

step 200, calculating the thickness of the inner wall of the cooling channel according to the thermal protection requirement of the thrust chamber, the heat flow distribution of the inner wall surface and the heat conduction performance of the material by combining the temperature of the inner side wall and the temperature of the outer side wall of the inner wall of the thrust chamber;

step 300, determining the height of the bottom of the cooling channel according to the thickness of the inner wall of the cooling channel, further determining the on-way molded lines of the bottom of the cooling channel, and determining data of each cooling channel section according to the number and the rib thickness of the cooling channel, further obtaining the on-way molded lines of four sides of the cooling channel section;

and step 400, according to the calculation results, calculating and determining the three-dimensional distribution of all points of the section of the engine, so that the three-dimensional shape of the cooling channel can be obtained through three-dimensional software design.

The design method of the equal hydraulic diameter cooling channel disclosed by the invention optimizes the traditional cooling channel, has small pressure loss in the channel, simple and reliable structure and obvious light weight effect, and can effectively reduce the mass of an engine. The cooling channel of design can be according to the difference of thrust chamber along journey cross-section, and its cross-section can be along with changing, can take away the heat of thrust chamber wall effectively, reduces the pressure loss of the fuel in the cooling channel, reduces engine structure weight. And the variable-section irregular curved surface cooling channel can be realized by a 3D printing technology, so that the time and the cost can be greatly reduced, and compared with the traditional manufacturing process, the variable-section irregular curved surface cooling channel can realize the excellent properties of high strength, ductility, fracture resistance, low variability and the like of the material.

Drawings

FIG. 1 is a schematic illustration of the steps of a design process according to one embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a cooling passage according to an embodiment of the present invention;

FIG. 3 is a schematic view of a cooling channel configuration according to an embodiment of the present invention.

Detailed Description

The detailed structure and implementation process of the present solution are described in detail below with reference to specific embodiments and the accompanying drawings.

As shown in fig. 1, in one embodiment of the present invention, a method for designing a cooling passage of equal hydraulic diameter for a rocket engine is disclosed, comprising the steps of:

step 100, setting cooling channels with fan-shaped cross sections to be distributed around a thrust chamber, and calculating an inner wall surface curve of each cooling channel by adopting a cylindrical coordinate system on the basis of taking the thrust chamber as a circular symmetrical structure according to the pressure of the thrust chamber, the expansion ratio of a spray pipe and the residence time requirement;

the cross-sectional shape of the cooling channel is shown in fig. 2, and an envelope-shaped line L of the inner wall surface of the engine is designed according to the conventional thought_inThe engine is a circular axisymmetric structure, and a cylindrical coordinate system and an equation L of a wall surface curve are adopted_inCan be written as:

L_in＝f_in(r_in,θ,x)

where x is an axial coordinate, for convenience, the center of the throat may be defined as the origin of the coordinate, r_inIs a curve L of the inner wall surface of the engine_inOf (c) is used.

Step 200, calculating the thickness of the inner wall of the cooling channel according to the thermal protection requirement of the thrust chamber, the heat flow distribution of the inner wall surface and the heat conduction performance of the material by combining the temperature of the inner side wall and the temperature of the outer side wall of the inner wall of the thrust chamber;

inner wall thickness delta₁The calculation formula of (T, r, θ, x) is as follows:

wherein q is_w(r, theta, x) is heat flow distribution, k (T, r, theta, x) is material heat-conducting property parameter, T_wgInner wall temperature, T, of the inner wall_wfThe inner wall temperature and the outer wall temperature.

Step 300, determining the height of the bottom of the cooling channel according to the thickness of the inner wall of the cooling channel, further determining the on-way molded lines of the bottom of the cooling channel, and determining data of each cooling channel section according to the number and the rib thickness of the cooling channel, further obtaining the on-way molded lines of four sides of the cooling channel section;

by the distance between the inner wall of the thrust chamber and the bottom of the cooling gallery, i.e. the thickness delta of the inner wall₁(T, r, θ, x), the height of the cooling channel bottom can be found to be:

r₁＝r_in+δ₁

further obtaining the on-way molded line L of the bottom of the cooling channel₁Comprises the following steps:

L₁＝f₁(r₁,0,x)

when the number of the cooling channels is n, the rib thickness is set as W, and the arc length of the bottom of the fan-shaped cooling channel is obtained as follows:

s₁(r,θ,x)＝2πr₁/n-W

the arc length at the top of the cooling channel is as follows:

s₂(r,θ,x)＝2πr₂/n-W

the heights of the two sides of the fan-shaped channel are as follows:

H＝r₂-r₁

according to the design principle of the cooling channel with the equal hydraulic diameter, the equal hydraulic diameter d is ensured_HThat means:

4A/C＝d_H＝Const

wherein A is the area of the fan-shaped cooling channel:

c is the circumference of the fan-shaped cooling channel:

C＝s₂+s₁+2H

the height of the top of the cooling channel is:

wherein the central angle corresponding to a single cooling channel is:

θ₁＝2π/n-W/r₁。

according to the relevant parameters of a single cooling channel, the top on-way line L of the cooling channel can be obtained₂Comprises the following steps:

L₂＝f₂(r₂,0,x)

one-side molded line L in width direction of cooling channel bottom₃Comprises the following steps:

L₃＝f₃(r₁,θ₁/2,x)

one-side molded line L in width direction of top of cooling channel₄Comprises the following steps:

L₄＝f₄(r₂,θ₁/2,x)

the height of the outer wall of the thrust chamber is the height of the top of the cooling channel plus the thickness delta of the outer wall₂(r, θ, x), where the outer wall thickness is designed according to the strength requirement, the thrust chamber outer wall height is:

r_out＝r₂+δ₂ (1)

further obtaining the molded line L of the outdoor wall surface of the thrust_out(ii) a Equation L for the outer wall curve_outCan be written as:

L_out＝f_out(r_out,θ,x)

and step 400, according to the calculation results, calculating and determining the three-dimensional distribution of all points of the section of the engine, so that the three-dimensional shape of the cooling channel can be obtained through three-dimensional software design.

From the above derivation, L is obtained as shown in FIG. 3_in，L₁，L₂，L₃，L₄，L_outAnd calculating the three-dimensional distribution of all points of the section of the engine after the equation of each line is obtained, designing the structure of the cooling channel of the engine by using three-dimensional entity design software according to the calculation result, and finally printing the design by 3D printing.

According to the design method of the equal hydraulic diameter cooling channel disclosed by the embodiment, the traditional cooling channel is optimized, pressure loss in the channel is small, the structure is simple and reliable, and the weight of the engine can be obviously lightened.

The cooling channel designed by the embodiment can change the section along with the change according to the difference of the section of the thrust chamber, can effectively take away the heat of the wall surface of the thrust chamber, reduces the pressure loss of fuel in the cooling channel and reduces the structural weight of the engine.

The variable cross-section irregular curved surface cooling channel designed by the embodiment can be realized by a 3D printing technology, the time and the cost can be greatly reduced, and compared with the traditional manufacturing process, the variable cross-section irregular curved surface cooling channel can realize the excellent properties of high strength, ductility, fracture resistance, low variability and the like of materials.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.