阅读说明：本技术 端面密封结构中摩擦温升情况的获取方法及系统 (Method and system for acquiring friction temperature rise condition in end face sealing structure ) 是由 庄宿国 黄丹 周芮 王良 宋勇 毛凯 于 2019-09-25 设计创作，主要内容包括：本发明公开了一种端面密封结构中摩擦温升情况的获取方法及系统,基于端面密封复杂的工况特征和结构尺寸,开展精确的摩擦温升精确计算。本发明基于运转试验的实测值获得了端面密封结构的实际工作条件,并以此为基础,结合端面密封结构的几何尺寸特征和工作过程中动静环不同区域的实际工况,通过仿真软件得到端面密封结构的热像图,从而准确、直观的获得到端面密封结构中摩擦温升情况。(The invention discloses a method and a system for acquiring friction temperature rise in an end face sealing structure, which are used for carrying out accurate friction temperature rise calculation based on complicated working condition characteristics and structural size of end face sealing. The invention obtains the actual working condition of the end face sealing structure based on the measured value of the running test, and based on the actual working condition, the invention combines the geometric dimension characteristics of the end face sealing structure and the actual working conditions of different areas of the dynamic and static rings in the working process, and obtains the thermal image of the end face sealing structure through simulation software, thereby accurately and intuitively obtaining the friction temperature rise condition in the end face sealing structure.)

1. A method for acquiring friction temperature rise conditions in an end face sealing structure, wherein the end face sealing structure comprises a static ring and a dynamic ring, and is characterized by comprising the following steps:

step 1: obtaining the pre-sealing temperature T in the chamber of the end face sealing structure under the dynamic operation condition₁And post-sealing temperature T₂And medium flow rate U before passing through the end face sealing structure₁And the flow velocity U of the medium passing through the end face sealing structure₂；

Step 2: constructing a heat flux density formula generated by a moving ring and a static ring in an end face sealing structure in the running friction process, wherein the specific calculation formula is as follows:

wherein i is the number of running friction surfaces of the moving ring and the static ring, and i is more than or equal to 7 and more than or equal to 4;

q_wiis the moving ring heat flow density, W/m²；

q_siIs the static ring heat flux density, W/m²；

h_sIs the thickness of the stationary ring, m;

h_wthe thickness of the rotating ring is m;

λ_smush static Ring thermal conductivity, W/(m. K);

λ_w(iii) kinetic Ring thermal conductivity, W/(m. K);

f is a friction coefficient, and the value range is 0.01-0.1;

d₁is the inner diameter of the stationary ring, m;

d₂is the outer diameter of the stationary ring, m;

n is the rotating speed of the rotating shaft for driving the rotating ring to rotate, and r/min;

p_cend face specific pressure pa;

and step 3: constructing a calculation formula of the convective heat transfer coefficient of the first area, the second area and the third area of the moving ring which are sealed by the end face, wherein the specific calculation formula is as follows:

wherein alpha is_w1Is the convective heat transfer coefficient W/m of the first area of the moving ring sealed by the end face²K; the first area of the moving ring is the outer circle surface of the moving ring;

α_w2is the convective heat transfer coefficient W/m of the second area of the moving ring sealed by the end face²K; the second area of the moving ring is the upper surface of the contact surface of the moving ring and the static ring;

α_w3is the convective heat transfer coefficient W/m of the third area of the end face sealing moving ring²K; the third area of the moving ring is the surface of the moving ring, which is far away from the contact surface of the moving ring and the static ring;

λ₁w/(m. K) as the thermal conductivity of the medium before end-face sealing;

D₁is the inner diameter of the rotating ring, m;

D₂the outer diameter of the rotating ring is m;

ν₁is the kinematic viscosity of the medium before sealing through the end face, m²/s；

P_rIs the prandtl number;

and 4, step 4: constructing a calculation formula of the convective heat transfer coefficient of the fourth area of the end face sealing moving ring, wherein the specific formula is as follows:

the fourth area of the moving ring is the lower surface of the contact surface of the moving ring and the static ring;

and 5: constructing a calculation formula of the convective heat transfer coefficient of the first area of the end face sealing static ring, wherein the specific formula is as follows:

wherein alpha is_s1Is the convective heat transfer coefficient W/m of the first area of the end face sealing static ring²K; the first area of the static ring is the outer circle surface of the static ring;

epsilon is a correction coefficient, and the value range is 1.2-2;

δ₁m is the gap between the outer side of the static ring and the inner wall of the cavity;

step 6: constructing a calculation formula of the convective heat transfer coefficient of the second area of the end face sealing static ring, wherein the specific formula is as follows:

wherein alpha is_s2Is the convective heat transfer coefficient W/m of the second area of the end face sealing static ring²K; the second area of the static ring is the inner circular surface of the static ring;

λ₂k, post-sealing medium thermal conductivity, W/(m &);

ν₂is the kinematic viscosity of the medium after sealing, m²/s；

δ₂The gap between the inner side of the stationary ring and the rotating shaft is m;

r_rthe radius of a rotating shaft for driving the rotating ring to rotate, m;

and 7: constructing an end face sealing structure model in ANSYS simulation software;

and 8: the T obtained in the step 1₁、T₂、U₁、U₂And inputting the calculation result of the step 2-6 into ANSYS simulation software, carrying out iterative solution to obtain a thermograph of the end face sealing structure model, and directly obtaining the friction temperature rise condition of the end face sealing structure from the thermograph.

2. The method for acquiring the friction temperature rise condition in the end face sealing structure according to claim 1, characterized in that: the medium before sealing is liquid oxygen, and the medium after sealing is air.

3. The utility model provides an acquisition system of friction temperature rise condition in end face seal structure which characterized in that: the temperature measuring device comprises a shell, a rotating shaft, a first temperature measuring instrument, a second temperature measuring instrument, a first speed measuring instrument, a second speed measuring instrument and an upper computer;

the end face sealing structure is positioned in the shell, a static ring of the end face sealing structure is fixedly arranged in the shell, and a dynamic ring is arranged on the rotating shaft; the end face sealing structure divides a cavity in the shell into a front sealing cavity and a rear sealing cavity;

a medium inlet, a first temperature measuring instrument and a first speed measuring instrument are arranged on the shell and communicated with the sealed front cavity;

a medium outlet, a second temperature measuring instrument and a second speed measuring instrument are arranged on the shell and communicated with the sealed rear cavity;

the first temperature measuring instrument, the first speedometer, the second temperature measuring instrument and the second speedometer are all connected with the upper computer.

4. The system for acquiring friction temperature rise condition in an end face sealing structure according to claim 3, characterized in that: the shell is of a split structure and comprises a front shell and a rear shell.

Technical Field

The invention belongs to the technical field of end face sealing of a turbopump of a liquid rocket engine, and relates to a method and a system for acquiring friction temperature rise in an end face sealing structure.

Background

The end face sealing structure is used as an important component of a turbo pump energy transmission system of the liquid rocket engine, is mainly used for sealing liquid oxidant, fuel, isolating fuel gas and the like, and if a fault occurs, the performance and the reliability of the engine are directly influenced, and even disastrous results are generated. Especially for the end face sealing of a turbo pump of a new generation of large carrier liquid oxygen kerosene engine in China, working parameters are continuously improved, the vibration impact environment is extremely severe, and a working medium has the characteristics of high pressure, low temperature, strong corrosion and the like, so that the working environment of an end face sealing friction pair is extremely severe, and the main failure mode of the end face sealing of the liquid rocket engine is that a moving ring and a static ring rotate relatively to generate friction so as to cause the temperature rise of the sealing end face, so that the end face is abraded, burned, hot cracked and the like, the sealing is unstable, and the leakage is increased. Because the end face sealing friction surface is in a closed contact state in the working process, the friction temperature rise condition cannot be measured by a test means.

Through retrieval, the current acquisition mode of friction temperature rise of the end face sealing structure of the liquid rocket engine is only related in partial documents, a mechanical sealing temperature field and thermal load deformation research for a turbo pump of the liquid rocket engine (rocket propulsion, 2014, 40 (5): 92-98) adopts a simple calculation method of sealing ring friction heat and convection heat transfer, but the heat flow density is not accurately calculated according to the change of the geometric dimension of the end face seal, the actual working state of the end face seal dynamic and static rings is not considered in the convection heat transfer coefficient, and the boundary condition setting mostly adopts the modes of hypothesis, empirical coefficient and the like, so that the accuracy of the calculation result is influenced.

Disclosure of Invention

Based on the above background, the invention provides a method and a system for acquiring the friction temperature rise condition in an end face sealing structure, which accurately calculate the friction temperature rise of the end face seal under the condition of combining the actual working state and the size of the end face sealing structure.

The technical scheme of the invention is as follows:

the invention provides a method for acquiring friction temperature rise in an end face sealing structure, wherein the end face sealing structure comprises a static ring and a dynamic ring, and the method comprises the following steps:

step 1: obtaining the pre-sealing temperature T in the chamber of the end face sealing structure under the dynamic operation condition₁And post-sealing temperature T₂And medium flow rate U before passing through the end face sealing structure₁And the flow velocity U of the medium passing through the end face sealing structure₂；

Step 2: constructing a heat flux density formula generated by a moving ring and a static ring in an end face sealing structure in the running friction process, wherein the specific calculation formula is as follows:

wherein i is the number of running friction surfaces of the moving ring and the static ring, and i is more than or equal to 7 and more than or equal to 4;

q_wiis the moving ring heat flow density, W/m²；

q_siIs the static ring heat flux density, W/m²；

h_sIs the thickness of the stationary ring, m;

h_wthe thickness of the rotating ring is m;

λ_smush static Ring thermal conductivity, W/(m. K);

λ_w(iii) kinetic Ring thermal conductivity, W/(m. K);

f is a friction coefficient, and the value range is 0.01-0.1;

d₁is the inner diameter of the stationary ring, m;

d₂is the outer diameter of the stationary ring, m;

n is the rotating speed of the rotating shaft for driving the rotating ring to rotate, r/min;

p_cend face specific pressure pa;

and step 3: constructing a calculation formula of the convective heat transfer coefficient of the first area, the second area and the third area of the moving ring which are sealed by the end face, wherein the specific calculation formula is as follows:

wherein alpha is_w1Is the convective heat transfer coefficient W/m of the first area of the moving ring sealed by the end face²K; the first area of the moving ring is the outer circle surface of the moving ring;

α_w2is the convective heat transfer coefficient W/m of the second area of the moving ring sealed by the end face²K; the second area of the moving ring is the upper surface of the contact surface of the moving ring and the static ring;

α_w3is the convective heat transfer coefficient W/m of the third area of the end face sealing moving ring²K; the third area of the moving ring is the surface of the moving ring, which is far away from the contact surface of the moving ring and the static ring;

λ₁w/(m. K) as the thermal conductivity of the medium before end-face sealing;

D₁is the inner diameter of the rotating ring, m;

D₂the outer diameter of the rotating ring is m;

ν₁is the kinematic viscosity of the medium before sealing through the end face, m²/s；

P_rIs the prandtl number;

and 4, step 4: constructing a calculation formula of the convective heat transfer coefficient of the fourth area of the end face sealing moving ring, wherein the specific formula is as follows:

the fourth area of the moving ring is the lower surface of the contact surface of the moving ring and the static ring;

and 5: constructing a calculation formula of the convective heat transfer coefficient of the first area of the end face sealing static ring, wherein the specific formula is as follows:

wherein alpha is_s1Is the convective heat transfer coefficient W/m of the first area of the end face sealing static ring²K; the first area of the static ring is the outer circle surface of the static ring;

epsilon is a correction coefficient, and the value range is 1.2-2;

δ₁m is the gap between the outer side of the static ring and the inner wall of the cavity;

step 6: constructing a calculation formula of the convective heat transfer coefficient of the second area of the end face sealing static ring, wherein the specific formula is as follows:

wherein alpha is_s2Is the convective heat transfer coefficient W/m of the second area of the end face sealing static ring²K; the second area of the static ring is the inner circular surface of the static ring;

λ₂k, post-sealing medium thermal conductivity, W/(m &);

ν₂is the kinematic viscosity of the medium after sealing, m²/s；

δ₂The gap between the inner side of the stationary ring and the rotating shaft is m;

r_rthe radius of a rotating shaft for driving the rotating ring to rotate, m;

and 7: constructing an end face sealing structure model in ANSYS simulation software;

and 8: the T obtained in the step 1₁、T₂、U₁、U₂And inputting the calculation result of the step 2-6 into ANSYS simulation software, carrying out iterative solution to obtain a thermograph of the end face sealing structure model, and directly obtaining the friction temperature rise condition of the end face sealing structure from the thermograph.

Further, the medium before sealing is liquid oxygen, and the medium after sealing is air.

Based on the method, the invention also provides a system for acquiring the friction temperature rise condition in the end face sealing structure, which comprises a shell, a rotating shaft, a first temperature measuring instrument, a second temperature measuring instrument, a first speed measuring instrument, a second speed measuring instrument and an upper computer;

the end face sealing structure is positioned in the shell, a static ring of the end face sealing structure is fixedly arranged in the shell, and a dynamic ring is arranged on the rotating shaft; the end face sealing structure divides a cavity in the shell into a front sealing cavity and a rear sealing cavity;

a medium inlet, a first temperature measuring instrument and a first speed measuring instrument are arranged on the shell and communicated with the sealed front cavity;

a medium outlet, a second temperature measuring instrument and a second speed measuring instrument are arranged on the shell and communicated with the sealed rear cavity;

the first temperature measuring instrument, the first speedometer, the second temperature measuring instrument and the second speedometer are all connected with the upper computer.

The shell is of a split structure and comprises a front shell and a rear shell.

The invention has the advantages that:

in view of the special working condition characteristics of the end face seal of the liquid rocket engine, the invention obtains the actual working condition of the end face seal based on the measured value, and based on the actual working condition, combines the geometric dimension characteristics of the end face seal and the actual working conditions of different areas of a moving ring and a static ring in the working process, provides an accurate method for obtaining the friction temperature rise condition of the end face seal of the liquid rocket engine, directly reflects the temperature rise change condition through a thermal image, improves the accuracy of the end face seal simulation, ensures the reliability of the liquid rocket engine, and shortens the model development period. Has certain popularization value.

Drawings

FIG. 1 is a flow chart of the present invention;

FIG. 2 is a schematic diagram of an acquisition system according to the present invention;

FIG. 3 is a distribution diagram of the regions of the end face seal configuration;

FIG. 4 is a diagram of a computational model of an end face seal configuration;

fig. 5 is a thermal image of an end face seal structure model.

The reference numbers are as follows:

1-shell, 2-rotating shaft, 3-first temperature measuring instrument, 4-second temperature measuring instrument, 5-first speed measuring instrument, 6-second speed measuring instrument, 7-end face sealing structure, 8-sealing front chamber, 9-sealing rear chamber, 10-medium inlet and 11-medium outlet.

Detailed Description

In order to make the objects, advantages and features of the present invention more clear, the method for obtaining the friction temperature rise in the end face sealing structure according to the present invention will be described in detail with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It should be noted that: the drawings are in simplified form and are not to precise scale, the intention being solely for the convenience and clarity of illustrating embodiments of the invention; secondly, the structures shown in the drawings are often part of the actual structure; again, the drawings may require different emphasis, sometimes on different proportions.

The method for acquiring the friction temperature rise condition in the end face sealing structure provided by the invention specifically realizes the flow, as shown in fig. 1:

step 1: obtaining the pre-sealing temperature T in the chamber of the end face sealing structure under the dynamic operation condition₁And post-sealing temperature T₂And medium flow rate U before passing through the end face sealing structure₁And the flow velocity U of the medium passing through the end face sealing structure₂；

Step 2: constructing a heat flux density formula generated by a moving ring and a static ring in an end face sealing structure in the running friction process, wherein the specific calculation formula is as follows:

formula (1):

formula (2):

wherein i is the number of running friction surfaces of the moving ring and the static ring, i is more than or equal to 7 and more than or equal to 4, and the preferred number is 5;

q_wiis the moving ring heat flow density, W/m²；

q_siIs the static ring heat flux density, W/m²；

h_sIs the thickness of the stationary ring, m;

h_wthe thickness of the rotating ring is m;

λ_smush static Ring thermal conductivity, W/(m. K);

λ_w(iii) kinetic Ring thermal conductivity, W/(m. K);

f is a friction coefficient, and the value range is 0.01-0.1;

d₁is the inner diameter of the stationary ring, m;

d₂is the outer diameter of the stationary ring, m;

n is the engine speed, r/min;

p_cend face specific pressure pa;

and step 3: constructing a calculation formula of the convective heat transfer coefficient of the first area, the second area and the third area of the moving ring which are sealed by the end face, wherein the specific calculation formula is as follows:

formula (3):

formula (4):

formula (5):

wherein alpha is_w1Is the convective heat transfer coefficient W/m of the first area of the moving ring sealed by the end face²K; the first area of the moving ring is the outer circle surface of the moving ring;

α_w2is the convective heat transfer coefficient W/m of the second area of the moving ring sealed by the end face²K; the movementThe second ring area is the upper surface of the contact surface of the moving ring and the static ring;

α_w3is the convective heat transfer coefficient W/m of the third area of the end face sealing moving ring²K; the third area of the moving ring is the surface of the moving ring, which is far away from the contact surface of the moving ring and the static ring;

λ₁w/(m. K) as the thermal conductivity of the medium before end-face sealing;

D₁is the inner diameter of the rotating ring, m;

D₂the outer diameter of the rotating ring is m;

ν₁is the kinematic viscosity of the medium before sealing through the end face, m²/s；

P_rIs the prandtl number;

and 4, step 4: constructing a calculation formula of the convective heat transfer coefficient of the fourth area of the end face sealing moving ring, wherein the specific formula is as follows:

formula (6):

the fourth area of the moving ring is the lower surface of the contact surface of the moving ring and the static ring;

and 5: constructing a calculation formula of the convective heat transfer coefficient of the first area of the end face sealing static ring, wherein the specific formula is as follows:

formula (7):

wherein alpha is_s1Is the convective heat transfer coefficient W/m of the first area of the end face sealing static ring²K; the first area of the static ring is the outer circle surface of the static ring;

epsilon is a correction coefficient, and the value range is 1.2-2;

δ₁is the outer side clearance of the static ring, m;

step 6: constructing a calculation formula of the convective heat transfer coefficient of the second area of the end face sealing static ring, wherein the specific formula is as follows:

formula (8):

wherein alpha is_s2Is the convective heat transfer coefficient W/m of the second area of the end face sealing static ring²K; the second area of the static ring is the inner circular surface of the static ring;

λ₂k, post-sealing medium thermal conductivity, W/(m &);

ν₂is the kinematic viscosity of the medium after sealing, m²/s；

δ₂The gap between the inner side of the stationary ring and the rotating shaft is m;

r_rthe radius of a rotating shaft for driving the rotating ring to rotate, m;

and 7: constructing an end face sealing structure model in ANSYS simulation software;

and 8: the T obtained in the step 1₁、T₂、U₁、U₂And inputting the calculation result of the step 2-6 into ANSYS simulation software, carrying out iterative solution to obtain a thermograph of the end face sealing structure model, and directly obtaining the friction temperature rise condition of the end face sealing structure from the thermograph.

Based on the above method, the present invention provides a specific example to further explain the present invention:

firstly, building a system for acquiring the friction temperature rise condition in the end face sealing structure, as shown in fig. 2, and comprising a shell 1, a rotating shaft 2, a first temperature measuring instrument 3, a second temperature measuring instrument 4, a first speed measuring instrument 5, a second speed measuring instrument 6 and an upper computer;

the end face sealing structure 7 is positioned in the shell 1, a static ring of the end face sealing structure is fixedly arranged in the shell, and a dynamic ring is arranged on the rotating shaft 2; the end face sealing structure divides a cavity in the shell 1 into a sealing front cavity 8 and a sealing rear cavity 9;

a medium inlet 10, a first temperature measuring instrument 3 and a first speed measuring instrument 5 are arranged on the shell 1 and communicated with the sealed front chamber 8;

a medium outlet 11, a second temperature measuring instrument 4 and a second speed measuring instrument 6 are arranged on the shell 1 and communicated with the sealed rear cavity 9;

the first temperature measuring instrument 3, the first speedometer 5, the second temperature measuring instrument 4 and the second speedometer 6 are all connected with the upper computer. ANSYS simulation software runs on the upper computer.

Before the end face seal assembly, the oil removal treatment must be carried out on the acquisition system and parts, and the installation is carried out after the dry and oil-stain-free nitrogen is used for blow-drying. The axial runout after assembly is 0.03mm, 0.5MPa nitrogen is introduced from a medium inlet, the leakage rate of the end face seal is 5 bubbles/min, the medium before sealing is liquid oxygen, the medium after sealing is air, the material of the moving ring of the end face seal is S-07 steel, and the material of the static ring is HCG graphite. Temperature T before and after sealing in operation₁＝-183℃、T₂43 ℃ medium flow rate U before and after sealing₁＝0.01m/s、U₂＝0.01m/s。

The media properties are shown in table 1.

TABLE 1 test media Properties

Medium	Lambda (coefficient of thermal conductivity)	V (kinematic viscosity)	Pr (Prandtl number)
				Liquid oxygen	0.1513W/(m﹒K)	1.7157×10-7m2/s	1.09
Air (a)	0.023W/(m﹒K)	1.61×10-5m2/s	0.7

The material properties are shown in table 2.

TABLE 2 Material Properties

Material	Lambda (coefficient of thermal conductivity)
		S-07 steel	14.2W/(m﹒K)
HCG	36W/(m﹒K)

The calculation parameters are shown in table 3.

TABLE 3 calculation of parameters

Secondly, calculating the heat flow density generated by the end face seal moving ring in the running friction process according to the formula (1), wherein five friction surfaces are taken in the example;

q_W1＝679201.2816W/m²

q_W2＝692453.9896W/m²

q_W3＝705706.6975W/m²

q_W4＝718959.4054W/m²

q_W5＝732212.1134W/m²

thirdly, calculating the heat flow density generated by the end face seal static ring in the running friction process according to the formula (2), wherein five friction surfaces are taken in the example;

q_s1＝883035.2524W/m²

q_s2＝900265.2085W/m²

q_s3＝917495.1647W/m²

q_s4＝934725.1208W/m²

q_s5＝951955.077W/m²

fourthly, calculating the convective heat transfer coefficient of the first area of the end face sealing moving ring according to a formula (3), wherein the calculation area is as shown in figure 3:

fifthly, calculating the convective heat transfer coefficient of the second area of the end face sealing moving ring according to a formula (4), wherein the calculation area is shown in figure 3:

sixthly, calculating the convective heat transfer coefficient of the third area of the end face sealing moving ring according to a formula (5), wherein the calculation area is shown in figure 3:

seventhly, calculating the convective heat transfer coefficient of the fourth area of the end face sealing moving ring according to the formula (6), wherein the calculation area is shown in figure 3:

eighthly, calculating the convective heat transfer coefficient of the first area of the end face sealing static ring according to a formula (7), wherein the calculation area is shown in figure 3:

ninthly, calculating the convective heat transfer coefficient of the second area of the end face sealing static ring according to a formula (8), wherein the calculation area is shown in figure 3:

tenthly, constructing an end face sealing structure model in ANSYS simulation software, as shown in FIG. 4;

eleven, mixing the T obtained in the step 1₁、T₂、U₁、U₂And inputting the calculation results of the steps 2-6 into ANSYS simulation software, carrying out iterative solution to obtain a thermograph of the end face sealing structure model, and directly obtaining the friction temperature rise condition of the end face sealing structure from the thermograph as shown in FIG. 5.

Finally, it should be noted that the above description is only for describing the preferred embodiments of the present invention, and not for limiting the scope of the present invention, and that any changes and modifications made by those skilled in the art according to the above disclosure are all within the scope of the appended claims.