CN113076606B - Aviation pipeline flaring joint leakage rate calculation method and system considering contact deformation - Google Patents

Aviation pipeline flaring joint leakage rate calculation method and system considering contact deformation Download PDF

Info

Publication number
CN113076606B
CN113076606B CN202110312603.5A CN202110312603A CN113076606B CN 113076606 B CN113076606 B CN 113076606B CN 202110312603 A CN202110312603 A CN 202110312603A CN 113076606 B CN113076606 B CN 113076606B
Authority
CN
China
Prior art keywords
joint
leakage rate
calculating
pipe joint
radius
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202110312603.5A
Other languages
Chinese (zh)
Other versions
CN113076606A (en
Inventor
骆彬
方珍义
程晖
张开富
程立鑫
邓力川
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Northwestern Polytechnical University
Original Assignee
Northwestern Polytechnical University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northwestern Polytechnical University filed Critical Northwestern Polytechnical University
Priority to CN202110312603.5A priority Critical patent/CN113076606B/en
Publication of CN113076606A publication Critical patent/CN113076606A/en
Application granted granted Critical
Publication of CN113076606B publication Critical patent/CN113076606B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/17—Mechanical parametric or variational design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/15—Vehicle, aircraft or watercraft design
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/08—Fluids
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Theoretical Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • General Engineering & Computer Science (AREA)
  • Pure & Applied Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Evolutionary Computation (AREA)
  • Computational Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mathematical Physics (AREA)
  • Computing Systems (AREA)
  • Algebra (AREA)
  • Automation & Control Theory (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Examining Or Testing Airtightness (AREA)

Abstract

The invention discloses a method and a system for calculating the leakage rate of an aviation pipeline flaring connector in consideration of contact deformation. The method comprises the following steps: based on the Hertz contact theory, converting the wave crest on the surface of the conduit into a semi-sphere on the surface of the conduit, converting the wave crest on the surface of the pipe joint into a semi-sphere on the surface of the pipe joint, calculating a contact threshold value based on the seepage theory and the effective medium theory according to the radius of the semi-sphere on the surface of the conduit, the radius of the semi-sphere on the surface of the pipe joint, the conduit parameter, the pipe joint parameter and the axial pretightening force, and calculating the leakage rate of the flared joint of the aviation pipeline according to the contact threshold value. By adopting the method and the system, the problems that the leak state of the oil seal test is difficult to quantitatively characterize and the judging precision is low after the hydraulic pipeline component level assembly of the aircraft can be solved.

Description

Aviation pipeline flaring joint leakage rate calculation method and system considering contact deformation
Technical Field
The invention relates to the technical field of assembly test and automation of aviation pipelines, in particular to a method and a system for calculating the leakage rate of an aviation pipeline flaring connector in consideration of contact deformation.
Background
In the assembly test process of the aircraft hydraulic pipeline system at the present stage, the aircraft hydraulic oil is used as a test medium, and the hydraulic test experiment vehicle is utilized to test the sealing performance of the joint of the hydraulic pipeline system after the aircraft component level assembly. The aviation pipeline joint has high sealing performance requirement and high working pressure, and the sealing performance test is required before working. The aviation pipeline joint usually uses flaring type joint, the sealing surface is a matched conical surface structure, and the matched conical surfaces mutually extrude and form a sealing ring under the action of the torque of an external nut. In practical situations, due to the manufacturing errors and assembly errors of the pipeline, the sealing structure formed by the matched conical surfaces is not an ideal sealing environment, such as the influences of surface roughness, roundness and the like, and tiny gaps exist between the matched conical surfaces in microcosmic, and leakage channels can be formed by the gaps when the pipeline is in oil communication, so that sealing failure is finally caused; if the fluid medium just does not form a leakage channel and flows out under the combined action of the axial pretightening force, the conical surface contact deformation and other factors, the sealing is realized.
The existing test process adopts No. 15 aviation hydraulic oil, and the result of the sealing performance test on the larger leakage position of the joint is easy to observe and judge by adopting the hydraulic oil, but is limited to a qualitative level. In addition, when the pipeline system is used for oil seal test, a plurality of small leakage positions exist, observation and characterization are not easy, and the investigation difficulty is high and the efficiency is low in the test process. The quantitative calculation and characterization of the leakage state at the joint are needed, and meanwhile, the relation between the joint leakage amount and the pressure loss is established, so that a foundation is laid for constructing a pressure response model of joint leakage.
In the field of mechanical seals, calculations concerning the leak rate of an interfacial seal have formed a set of practical theories. The theory is mainly based on an energy equation of fluid, and the effective medium theory solves the problem of fluid movement flux under a small gap on the basis of researching fluid characteristics, gives out flow characteristic coefficients of different fluid media under a microscopic leakage channel, and can be used for constructing a leakage quantity model. The existing leakage quantity model is constructed under the bearing contact sealing working condition, and is used for calculating the sealing leakage under the cylindrical surface contact state. This is different from the operating mode of an aircraft flared joint:
(1) The joint matched sealing surface is a conical surface, so that the joint is more easily influenced by assembly errors;
(2) After the joint sealing interface is assembled, larger interface pressure exists, and the gap structure is changed.
The aviation flaring type connector is of a conical surface-conical surface sealing structure, is influenced by assembly errors, manufacturing errors and the like, and is easy to form sealing defects and difficult to control when matched with the conical surface. Because pipeline hydraulic oil operating pressure is great, in order to guarantee the leakproofness, there is great interface pressure after the joint seal interface assembly, and seal structure microscopic clearance produces the change, from roughness scale, the crest is flattened, and the trough is filled, forms more complicated new seal structure. The gap structure for the existing leakage rate model is generally the interface pressure which does not generate more obvious Hertz contact, so that the leakage rate error for calculating the aviation flaring connector is larger.
Disclosure of Invention
The invention aims to provide a method and a system for calculating the leakage rate of an aviation pipeline flaring joint in consideration of contact deformation, which can solve the problems that after an aircraft hydraulic pipeline part is assembled, the oil density test leakage state is difficult to quantitatively characterize and the judgment precision is low.
In order to achieve the above object, the present invention provides the following solutions:
a method for calculating the leakage rate of an aviation pipeline flaring connector comprises the following steps:
converting the wave crest of the conduit surface into a hemispherical body of the conduit surface and converting the wave crest of the pipe joint surface into a hemispherical body of the pipe joint surface based on the Hertz contact theory;
acquiring the radius of the semi-sphere on the surface of the conduit, the radius of the semi-sphere on the surface of the pipe joint, the parameters of the conduit, the parameters of the pipe joint and the axial pretightening force;
calculating a contact threshold based on a seepage theory and an effective medium theory according to the radius of the pipe surface hemisphere, the radius of the pipe joint surface hemisphere, the pipe parameter, the pipe joint parameter and the axial pretightening force;
and calculating the leakage rate of the flared joint of the aviation pipeline according to the contact threshold value.
Optionally, the calculating the contact threshold according to the radius of the pipe surface hemisphere, the radius of the pipe joint surface hemisphere, the pipe parameter, the pipe joint parameter and the axial pretightening force based on a seepage theory and an effective medium theory specifically includes:
the contact threshold is calculated according to the following formula:
wherein,
R 1 ＝R 2
wherein P is c For the contact threshold value, R 1 Radius of the hemisphere of the catheter surface, R 2 Radius of hemispheroid, E, of the surface of the pipe joint * To combine the effective moduli of the hemispheres, E 1 Young's modulus, v of the catheter 1 Poisson's ratio for catheter, F N For loading, F N The axial pretightening force F is obtained by decomposing the number of hemispheres.
Optionally, the calculating the leakage rate of the flared joint of the aviation pipeline according to the contact threshold specifically includes:
judging whether the contact threshold is within a preset range or not to obtain a first judgment result;
if the first judgment result is yes, acquiring parameters of sealing fluid, and calculating the leakage rate of the flaring joint of the aviation pipeline according to the parameters of the sealing fluid and the contact threshold value;
if the first judgment result is negative, the leakage rate of the flaring joint of the aviation pipeline is 0.
Optionally, the calculating the leakage rate of the flared joint of the aviation pipeline according to the parameter of the sealing fluid and the contact threshold value specifically includes:
calculating the leakage rate of the flared joint of the aviation pipeline according to the following formula:
wherein,
d＝(d 1 +d 2 )/2
R max1 ＝R max2
R a1 ＝R a2
wherein Q is the leakage rate of the flared joint of the aviation pipeline, d is the equivalent inlet diameter of sealing fluid, d 1 Is the inner diameter of the catheter, d 2 For sealing the end circumference diameter of the contact surface, h is the average leakage gap, R max1 Is the maximum depth of microscopic surface unevenness of an upper sealing surface, the upper sealing surface is a conduit surface, R max2 For the maximum depth of microscopic surface unevenness of the lower sealing surface, the lower sealing surface is a pipe joint surface, R a1 R is the average value of the microscopic roughness of the upper sealing surface a2 The average value of the microroughness of the lower sealing surface is Δp, which is the pressure difference between the inside and the outside of the sealing fluid, b is the width of the leakage channel, and η is the hydrodynamic viscosity.
The invention also provides a system for calculating the leakage rate of the flared joint of the aviation pipeline, which comprises the following steps:
the hemispherical conversion module is used for converting the wave crest on the surface of the conduit into a hemispherical body on the surface of the conduit and converting the wave crest on the surface of the pipe joint into a hemispherical body on the surface of the pipe joint based on the Hertz contact theory;
the data acquisition module is used for acquiring the radius of the semi-sphere on the surface of the guide pipe, the radius of the semi-sphere on the surface of the pipe joint, the parameters of the guide pipe, the parameters of the pipe joint and the axial pretightening force;
the contact threshold calculation module is used for calculating a contact threshold based on a seepage theory and an effective medium theory according to the radius of the pipe surface hemisphere, the radius of the pipe joint surface hemisphere, the pipe parameter, the pipe joint parameter and the axial pretightening force;
and the aviation pipeline flaring connector leakage rate calculation module is used for calculating the aviation pipeline flaring connector leakage rate according to the contact threshold value.
Optionally, the contact threshold calculating module specifically includes:
a contact threshold calculating unit for calculating a contact threshold according to the following formula:
wherein,
R 1 ＝R 2
wherein P is c For the contact threshold value, R 1 Radius of the hemisphere of the catheter surface, R 2 Radius of hemispheroid, E, of the surface of the pipe joint * To combine the effective moduli of the hemispheres, E 1 Young's modulus, v of the catheter 1 Poisson's ratio for catheter, F N For loading, F N The axial pretightening force F is obtained by decomposing the number of hemispheres.
Optionally, the aviation pipeline flaring connector leakage rate calculation module specifically includes:
the aviation pipeline flaring connector leakage rate calculation unit is used for judging whether the contact threshold value is in a preset range or not to obtain a first judgment result; if the first judgment result is yes, acquiring parameters of sealing fluid, and calculating the leakage rate of the flaring joint of the aviation pipeline according to the parameters of the sealing fluid and the contact threshold value; if the first judgment result is negative, the leakage rate of the flaring joint of the aviation pipeline is 0.
Optionally, the aviation pipeline flaring connector leakage rate calculating unit specifically includes:
the aviation pipeline flaring connector leakage rate calculation subunit is used for calculating the aviation pipeline flaring connector leakage rate according to the following formula:
wherein,
d＝(d 1 +d 2 )/2
R max1 ＝R max2
R a1 ＝R a2
wherein Q is the leakage rate of the flared joint of the aviation pipeline, d is the equivalent inlet diameter of sealing fluid, d 1 Is the inner diameter of the catheter, d 2 For sealing the end circumference diameter of the contact surface, h is the average leakage gap, R max1 Is the maximum depth of microscopic surface unevenness of an upper sealing surface, the upper sealing surface is a conduit surface, R max2 For the maximum depth of microscopic surface unevenness of the lower sealing surface, the lower sealing surface is a pipe joint surface, R a1 R is the average value of the microscopic roughness of the upper sealing surface a2 The average value of the microroughness of the lower sealing surface is Δp, which is the pressure difference between the inside and the outside of the sealing fluid, b is the width of the leakage channel, and η is the hydrodynamic viscosity.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a method and a system for calculating the leakage rate of an aviation pipeline flaring connector in consideration of contact deformation, which are used for converting a wave crest on a conduit surface into a hemispherical body on the conduit surface based on a Hertz contact theory, converting a wave crest on a pipe joint surface into a hemispherical body on the pipe joint surface, calculating a contact threshold value based on a seepage theory and an effective medium theory according to the radius of the hemispherical body on the conduit surface, the radius of the hemispherical body on the pipe joint surface, a conduit parameter, a pipe joint parameter and an axial pretightening force, and calculating the leakage rate of the aviation pipeline flaring connector according to the contact threshold value. The invention can solve the problems that the leak state of the oil seal test is difficult to quantitatively characterize and the judging precision is lower after the hydraulic pipeline components of the aircraft are assembled.
In addition, the invention can realize the calculation of the joint leakage rate in the static connection state, solve the problem that the smaller leakage amount in the test of the hydraulic oil used by the existing hydraulic pipeline cannot be quantitatively represented, provide theoretical support for developing the leakage instrument in the tiny leakage state, calculate the leakage rate of different fluid media, realize the equivalent conversion of the internal pressure of the pipeline in the same leakage state, and facilitate the subsequent calculation of the equivalent relationship of the pressure response of different test media in the same leakage state of the joint.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for calculating the leakage rate of an aircraft pipeline flaring connector taking contact deformation into consideration in an embodiment of the invention;
FIG. 2 is a schematic diagram of calculation and optimization of the leak rate of a flare fitting in an embodiment of the present invention;
FIG. 3 is a schematic view of the microstructure of a flare fitting in accordance with an embodiment of the present invention;
FIG. 4 is a schematic diagram of Hertz contact deformation in accordance with an embodiment of the present invention;
FIG. 5 is a schematic diagram of effective contact area calculation in an embodiment of the present invention;
FIG. 6 is a schematic diagram of interface pressure calculation in an embodiment of the invention;
FIG. 7 is a graph showing the joint leakage rate calculation parameters according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention aims to provide a method and a system for calculating the leakage rate of an aviation pipeline flaring joint in consideration of contact deformation, which can solve the problems that after an aircraft hydraulic pipeline part is assembled, the oil density test leakage state is difficult to quantitatively characterize and the judgment precision is low.
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
Examples
Fig. 1 is a flowchart of a method for calculating a leakage rate of an aircraft pipeline flaring connector considering contact deformation in an embodiment of the present invention, as shown in fig. 1, a method for calculating a leakage rate of an aircraft pipeline flaring connector considering contact deformation includes:
step 101: based on the Hertz contact theory, the catheter surface wave crest is converted into a catheter surface hemisphere, and the pipe joint surface wave crest is converted into a pipe joint surface hemisphere.
Step 102: the radius of the semi-sphere of the surface of the conduit, the radius of the semi-sphere of the surface of the pipe joint, the parameters of the conduit, the parameters of the pipe joint and the axial pretightening force are obtained.
Step 103: and calculating a contact threshold based on a seepage theory and an effective medium theory according to the radius of the semi-sphere of the surface of the conduit, the radius of the semi-sphere of the surface of the pipe joint, the parameters of the conduit, the parameters of the pipe joint and the axial pretightening force.
Step 103, specifically includes:
the contact threshold is calculated according to the following formula:
wherein,
R 1 ＝R 2
wherein P is c For the contact threshold value, R 1 Radius of the hemisphere of the catheter surface, R 2 Radius of hemispheroid, E, of the surface of the pipe joint * To combine the effective moduli of the hemispheres, E 1 Young's modulus, v of the catheter 1 Poisson's ratio for catheter, F N For loading, F N The axial pretightening force F is obtained by decomposing the number of hemispheres.
Step 104: and calculating the leakage rate of the flared joint of the aviation pipeline according to the contact threshold value.
Step 104 specifically includes:
judging whether the contact threshold is within a preset range or not to obtain a first judgment result;
if the first judgment result is yes, acquiring parameters of the sealing fluid, and calculating the leakage rate of the flaring joint of the aviation pipeline according to the parameters of the sealing fluid and the contact threshold value;
if the first judgment result is negative, the leakage rate of the flared joint of the aviation pipeline is 0.
The method for calculating the leakage rate of the flared joint of the aviation pipeline according to the parameters of the sealing fluid and the contact threshold value specifically comprises the following steps:
calculating the leakage rate of the flared joint of the aviation pipeline according to the following formula:
wherein,
d＝(d 1 +d 2 )/2
R max1 ＝R max2
R a1 ＝R a2
wherein Q is the leakage rate of the flared joint of the aviation pipeline, d is the equivalent inlet diameter of sealing fluid, d 1 Is the inner diameter of the catheter, d 2 For sealing the end circumference diameter of the contact surface, h is the average leakage gap, R max1 For the maximum depth of microscopic surface unevenness of the upper sealing surface, the upper sealing surface is the surface of the conduit, R max2 For the maximum depth of microscopic surface unevenness of the lower sealing surface, the lower sealing surface is a pipe joint surface, R a1 R is the average value of the microscopic roughness of the upper sealing surface a2 The average value of the microroughness of the lower sealing surface is Δp, which is the pressure difference between the inside and the outside of the sealing fluid, b is the width of the leakage channel, and η is the hydrodynamic viscosity.
The invention also provides an aviation pipeline flaring connector leakage rate calculation system considering contact deformation, which comprises the following steps:
the hemispherical conversion module is used for converting the wave crest on the surface of the conduit into a hemispherical body on the surface of the conduit and converting the wave crest on the surface of the pipe joint into a hemispherical body on the surface of the pipe joint based on the Hertz contact theory.
The data acquisition module is used for acquiring the radius of the semi-sphere of the surface of the conduit, the radius of the semi-sphere of the surface of the pipe joint, the parameters of the conduit, the parameters of the pipe joint and the axial pretightening force.
The contact threshold calculation module is used for calculating a contact threshold based on a seepage theory and an effective medium theory according to the radius of the semi-sphere of the surface of the conduit, the radius of the semi-sphere of the surface of the pipe joint, the conduit parameter, the pipe joint parameter and the axial pretightening force.
And the aviation pipeline flaring connector leakage rate calculation module is used for calculating the aviation pipeline flaring connector leakage rate according to the contact threshold value.
Wherein,
the touch threshold calculation module specifically comprises:
a contact threshold calculating unit for calculating a contact threshold according to the following formula:
wherein,
R 1 ＝R 2
wherein P is c For the contact threshold value, R 1 Radius of the hemisphere of the catheter surface, R 2 Radius of hemispheroid, E, of the surface of the pipe joint * To combine the effective moduli of the hemispheres, E 1 Young's modulus, v of the catheter 1 Poisson's ratio for catheter, F N For loading, F N The axial pretightening force F is obtained by decomposing the number of hemispheres.
The aviation pipeline flaring connector leakage rate calculation module specifically comprises:
the aviation pipeline flaring connector leakage rate calculation unit is used for judging whether the contact threshold value is in a preset range or not to obtain a first judgment result; if the first judgment result is yes, acquiring parameters of the sealing fluid, and calculating the leakage rate of the flaring joint of the aviation pipeline according to the parameters of the sealing fluid and the contact threshold value; if the first judgment result is negative, the leakage rate of the flared joint of the aviation pipeline is 0.
The aviation pipeline flaring connector leakage rate calculating unit specifically comprises:
the aviation pipeline flaring connector leakage rate calculation subunit is used for calculating the aviation pipeline flaring connector leakage rate according to the following formula:
wherein,
d＝(d 1 +d 2 )/2
R max1 ＝R max2
R a1 ＝R a2
wherein Q is the leakage rate of the flared joint of the aviation pipeline, d is the equivalent inlet diameter of sealing fluid, d 1 Is the inner diameter of the conduit, d2 is the circumferential diameter of the end of the sealing contact surface, h is the average leakage gap, R max1 For the maximum depth of microscopic surface unevenness of the upper sealing surface, the upper sealing surface is the surface of the conduit, R max2 For the maximum depth of microscopic surface unevenness of the lower sealing surface, the lower sealing surface is a pipe joint surface, R a1 R is the average value of the microscopic roughness of the upper sealing surface a2 The average value of the microroughness of the lower sealing surface is Δp, which is the pressure difference between the inside and the outside of the sealing fluid, b is the width of the leakage channel, and η is the hydrodynamic viscosity.
In order to solve the problem that the existing detection method cannot realize quantitative characterization of the leakage quantity of the aviation flaring type pipeline joint, the invention provides a joint leakage rate calculation model applied to the sealing performance test of the aircraft part hydraulic pipeline joint, and the calculation of the sealing critical value and the leakage rate of the aircraft hydraulic pipeline joint can be realized.
The joint leakage rate quantitative calculation method is based on the constructed joint cone-cone matching surface microscopic sealing structure model, combines the fluid sealing characteristics, establishes a joint sealing critical value and a leakage model, can be used for calculating the leakage rate of a flaring joint, and can be further used for calculating gas-liquid equivalent pressure and the like when the joint leaks.
The method comprises the following implementation steps:
1. analyzing the sealing structure form of the flaring type joint, reconstructing the surface morphology of the joint matching interface, analyzing the characteristics of the clearance parameter of the interface to be optimized based on the existing bearing leakage rate model, and calculating the contact deformation of the matching interface under different sealing states based on the seepage theory.
2. And calculating the equivalent gap height after contact deformation through the Hertz contact theory, and substituting the equivalent gap height into the existing leakage rate calculation formula to obtain an optimized leakage rate calculation model. And respectively calculating the gap height of the sealing surface according to the theoretical complete contact sealing state and the leakage state, and substituting the gap height into a calculation model to obtain the sectional expression of the leakage rate model.
The method mainly comprises the technical ideas that the influence of deformation of a joint sealing matching surface on the leakage rate is considered, the deformation of a joint microscopic sealing gap structure is calculated by utilizing a Hertz contact theory, an existing leakage rate calculation model is optimized, the critical deformation of the joint sealing zero leakage rate is calculated based on a seepage theory, and an optimized leakage rate formula is expressed in a segmented mode.
As shown in fig. 2, α in fig. 2 is the cone angle of the flared joint conical surface of 74 degrees, β is the assembly error eccentric angle, and the value is 0 when calculated as an ideal state without the eccentric angle.
The principle of optimizing the leakage rate of the aviation flaring connector is as follows:
the aviation flaring connector has the sealing mode that the inner surface of a flaring pipe is matched with the conical surface of the outer surface of a pipe joint, and under the action of a pretightening moment, the two conical surfaces are mutually extruded to form a sealing structure. From the macro scale, the two conical surfaces form a complete sealing structure without gaps; however, from the microscopic scale, the surface of the part does not form dense contact, microscopic gaps exist due to the influence of surface roughness, and deformation gaps generated after the sealing surface is extruded are less, but still exist. When the gap reaches a certain height and area, a leakage path is formed, thereby generating leakage. Therefore, firstly solving the sealing structure gap of the surface roughness scale, secondly solving the contact deformation of the interface, then dividing the leakage state according to the deformation, and finally establishing an optimization model.
S1: part surface roughness is typically quantified using statistics, most surface roughness is random, the distribution of surface heights typically follows a gaussian distribution, and the average leakage gap h of the metal seal can be obtained from a seal model of parallel roughened surfaces:
wherein h is the average leakage gap, and is equal in value to the gap height formed by the rough depth, R max1 、R max2 R is the maximum depth of microscopic surface unevenness of the upper sealing surface and the lower sealing surface a1 、R a2 The average of the microroughness of the upper and lower sealing surfaces can be measured by a coarseness meter, and the conduit surface is defined as the upper sealing surface, and the pipe joint surface is defined as the lower sealing surface, as shown in fig. 3.
S2: analyzing the extrusion deformation process of the rough surface based on the Hertz contact theory, and calculating the contact deformation delta of the sealing surface under different interface pressures;
according to the description in S1, the microscopic topography distribution of the roughened surface has randomness, which is inconvenient for the contact deformation calculation. Thus, the theory of hertz contact works as follows: extracting a set of surface peaks, simplified as hemispheres, the hertz contact assumes that the deformation is elastic, the size of the contact area is small relative to the overall size of the object, and the radius can be considered constant. The solutions of contact deformation, contact area and contact area stress are solved by the traditional Hertz theory.
Under the action of the joint pretightening moment, the sealing interface generates interface pressure, and the microstructure generates:
contact deformation:
contact area: a=pi a 2 ＝πRδ (3)
After contact deformation, a circular area is formed, and the radius a is given by:
f as shown in FIG. 4 N The radius of the sphere of the surface of the guide pipe and the joint is R respectively for load 1 And R is 2 The radius of curvature is:
effective modulus E of the Combined hemispheres * The definition is as follows:
wherein E is 1 、E 2 、v 1 、v 2 Young's modulus and Poisson's ratio of the catheter and the joint, respectively.
As the guide pipe and the joint are made of stainless steel, the surface roughness processing grades are R a 0.8(R a 0.8 represents a roughness grade), and the above formulas (1), (5) and (6) are simplified as follows:
R max1 ＝R max2 ，R a1 ＝R a2 ，R 1 ＝R 2 ，E 1 ＝E 2 ，v 1 ＝v 2 ；
R＝R 1 ＝R 2 (8)
s3: based on a seepage theory and an effective medium theory, analyzing contact deformation conditions forming zero leakage of an interface, and simultaneously calculating the gap amounts of sealing surfaces in different sealing states;
the sealing state under the microscopic gap structure is complex due to the influence of the liquid molecular size and dynamic viscosity, and certain uncertainty exists. With the micro-gap structure, the medium can penetrate the material from the top end until reaching the bottom. Until the 80 s of the 19 th century, a complete demonstration of the percolation threshold of a two-dimensional square was given by Ha Li kestent, at which no leakage path was formed at a percolation threshold of 0.5. In actual elastic contact, the Bruggeman contact threshold is 0.42 according to the Bruggeman effective medium theory, and is regarded as a zero leakage state.
Relevant parameters defined according to the hertz contact theory, the seepage theory and the effective medium theory are as follows:
A * : an effective contact area;
A 0 : ideal contact area;
P c : a contact threshold;
P c ＝A * /A 0
and S2, the materials and the roughness of the guide pipe and the joint are the same, so that part of formulas are simplified. Here, for ease of calculation, one of the hemispheres in the set of hemispheres is extracted for the representation and calculation of the effective contact area. The two hemispheres are identical in size, and the axial contact deformation of each hemispheroid is half of the total deformation. When the rough surface is equivalent to a hemisphere, the range is a circumscribed square with a round ground. As shown in particular in fig. 5.
Effective contact area:
equation (3) is known to solve for the contact area as: a=pi a 2 ＝πRδ
Solving the simultaneous equation (8):
bringing back formula (2), simultaneous formulas (4), (9), yields:
in the formula (12), R 1 F is determined according to the surface roughness grade N The axial pre-tightening force F can be obtained by decomposing the axial pre-tightening force F according to the number N of equivalent hemispheres, and particularly as shown in FIG. 6, the axial pre-tightening force F can be obtained by simulation software ABAQUS.
Gap after deformation: h=h- δ (13)
S4: based on the existing leakage model, the model is optimized by combining the calculation work of the S2-S3 part;
the leak rate calculation formula under the boundary friction condition according to the Mayer derivation:
and according to the gap H after the optimization of the S2 and the S3 part, obtaining an optimized leakage rate calculation model:
q= { 0|other }
Q= { 0|other } d is the equivalent entry diameter of the sealing fluid, d 1 Is the inner diameter of the catheter, d 2 For the circumferential diameter of the end of the sealing contact surface, b is the width of the leakage channel, the value is equal to the width of the sealing band, the value can be obtained by simulation, deltap is the pressure difference between the inside and the outside of the sealing fluid, and eta is the hydrodynamic viscosity MPa's. The parameter correspondence is shown in fig. 7. In the calculation, the leakage state is determined by the calculation formula (12) and then the calculation is performed by the use of the calculation formula (14).
The invention can realize the calculation of the joint leakage rate in the static connection state, solve the problem that the smaller leakage amount in the test of the hydraulic oil used by the existing hydraulic pipeline cannot be quantitatively represented, and the established leakage rate calculation model can provide theoretical support for developing a leakage instrument in the micro leakage state. The established leakage rate optimization calculation model can calculate the leakage rates of different fluid media, can realize equivalent conversion of the internal pressure of the pipeline under the same leakage state, and is convenient for the subsequent calculation of the equivalent relationship of pressure response of different test media under the same leakage state of the joint.
The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to assist in understanding the methods of the present invention and the core ideas thereof; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In summary, the present description should not be construed as limiting the invention.

Claims (4)

1. The method for calculating the leakage rate of the flared joint of the aviation pipeline is characterized by comprising the following steps of:
converting the wave crest of the conduit surface into a hemispherical body of the conduit surface and converting the wave crest of the pipe joint surface into a hemispherical body of the pipe joint surface based on the Hertz contact theory;
acquiring the radius of the semi-sphere on the surface of the conduit, the radius of the semi-sphere on the surface of the pipe joint, the parameters of the conduit, the parameters of the pipe joint and the axial pretightening force;
calculating a contact threshold based on a seepage theory and an effective medium theory according to the radius of the pipe surface hemisphere, the radius of the pipe joint surface hemisphere, the pipe parameter, the pipe joint parameter and the axial pretightening force;
calculating the leakage rate of the flared joint of the aviation pipeline according to the contact threshold value;
wherein the contact threshold is calculated according to the following formula:
wherein,
R 1 ＝R 2
wherein P is c For the contact threshold value, R 1 Radius of the hemisphere of the catheter surface, R 2 Radius of hemispheroid, E, of the surface of the pipe joint * To combine the effective moduli of the hemispheres, E 1 Young's modulus, v of the catheter 1 Poisson's ratio for catheter, F N For loading, F N The axial pretightening force F is obtained by decomposing according to the number of hemispheres;
calculating the leakage rate of the flared joint of the aviation pipeline according to the following formula:
wherein,
d＝(d 1 +d 2 )/2
R max1 ＝R max2
R a1 ＝R a2
wherein Q is the leakage rate of the flared joint of the aviation pipeline, d is the equivalent inlet diameter of sealing fluid, d 1 Is the inner diameter of the catheter, d 2 For sealing the end circumference diameter of the contact surface, h is the average leakage gap, R max1 For the maximum depth of microscopic surface unevenness of the upper sealing surface, the upper sealing surface is the surface of the conduit, R max2 For the maximum depth of microscopic surface unevenness of the lower sealing surface, the lower sealing surface is a pipe joint surface, R a1 R is the average value of the microscopic roughness of the upper sealing surface a2 The average value of the microroughness of the lower sealing surface is Δp, which is the pressure difference between the inside and the outside of the sealing fluid, b is the width of the leakage channel, and η is the hydrodynamic viscosity.
2. The method for calculating the leakage rate of the flared joint of the aviation pipeline according to claim 1, wherein the calculating the leakage rate of the flared joint of the aviation pipeline according to the contact threshold value specifically comprises:
judging whether the contact threshold is within a preset range or not to obtain a first judgment result;
if the first judgment result is yes, acquiring parameters of sealing fluid, and calculating the leakage rate of the flaring joint of the aviation pipeline according to the parameters of the sealing fluid and the contact threshold value;
if the first judgment result is negative, the leakage rate of the flaring joint of the aviation pipeline is 0.
3. An aircraft pipeline flare joint leak rate calculation system, comprising:
the hemispherical conversion module is used for converting the wave crest on the surface of the conduit into a hemispherical body on the surface of the conduit and converting the wave crest on the surface of the pipe joint into a hemispherical body on the surface of the pipe joint based on the Hertz contact theory;
the data acquisition module is used for acquiring the radius of the semi-sphere on the surface of the guide pipe, the radius of the semi-sphere on the surface of the pipe joint, the parameters of the guide pipe, the parameters of the pipe joint and the axial pretightening force;
the contact threshold calculation module is used for calculating a contact threshold based on a seepage theory and an effective medium theory according to the radius of the pipe surface hemisphere, the radius of the pipe joint surface hemisphere, the pipe parameter, the pipe joint parameter and the axial pretightening force;
the aviation pipeline flaring connector leakage rate calculation module is used for calculating the aviation pipeline flaring connector leakage rate according to the contact threshold value;
wherein the contact threshold is calculated according to the following formula:
wherein,
R 1 ＝R 2
wherein P is c For the contact threshold value, R 1 Radius of the hemisphere of the catheter surface, R 2 Radius of hemispheroid, E, of the surface of the pipe joint * To combine the effective moduli of the hemispheres, E 1 Young's modulus, v of the catheter 1 Poisson's ratio for catheter, F N For loading, F N The axial pretightening force F is obtained by decomposing according to the number of hemispheres;
calculating the leakage rate of the flared joint of the aviation pipeline according to the following formula:
wherein,
d＝(d 1 +d 2 )/2
R max1 ＝R max2
R a1 ＝R a2
wherein Q is the leakage rate of the flared joint of the aviation pipeline, d is the equivalent inlet diameter of sealing fluid, d 1 Is the inner diameter of the catheter, d 2 For sealing the end circumference diameter of the contact surface, h is the average leakage gap, R max1 For the maximum depth of microscopic surface unevenness of the upper sealing surface, the upper sealing surface is the surface of the conduit, R max2 For the maximum depth of microscopic surface unevenness of the lower sealing surface, the lower sealing surface is a pipe joint surface, R a1 R is the average value of the microscopic roughness of the upper sealing surface a2 The average value of the microroughness of the lower sealing surface is Δp, which is the pressure difference between the inside and the outside of the sealing fluid, b is the width of the leakage channel, and η is the hydrodynamic viscosity.
4. The aircraft line flare fitting leak rate calculation system of claim 3, wherein the aircraft line flare fitting leak rate calculation module specifically comprises:
the aviation pipeline flaring connector leakage rate calculation unit is used for judging whether the contact threshold value is in a preset range or not to obtain a first judgment result; if the first judgment result is yes, acquiring parameters of sealing fluid, and calculating the leakage rate of the flaring joint of the aviation pipeline according to the parameters of the sealing fluid and the contact threshold value; if the first judgment result is negative, the leakage rate of the flaring joint of the aviation pipeline is 0.
CN202110312603.5A 2021-03-24 2021-03-24 Aviation pipeline flaring joint leakage rate calculation method and system considering contact deformation Active CN113076606B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110312603.5A CN113076606B (en) 2021-03-24 2021-03-24 Aviation pipeline flaring joint leakage rate calculation method and system considering contact deformation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110312603.5A CN113076606B (en) 2021-03-24 2021-03-24 Aviation pipeline flaring joint leakage rate calculation method and system considering contact deformation

Publications (2)

Publication Number Publication Date
CN113076606A CN113076606A (en) 2021-07-06
CN113076606B true CN113076606B (en) 2024-03-26

Family

ID=76613647

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110312603.5A Active CN113076606B (en) 2021-03-24 2021-03-24 Aviation pipeline flaring joint leakage rate calculation method and system considering contact deformation

Country Status (1)

Country Link
CN (1) CN113076606B (en)

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1748371A1 (en) * 2005-07-26 2007-01-31 Denso Corporation Apparatus and method for determining patterns of damage being caused in rolling contact element
WO2009135639A1 (en) * 2008-05-05 2009-11-12 Aktiebolaget Skf Determining hydrostatic leakage
CN107229778A (en) * 2017-05-15 2017-10-03 武汉工程大学 The compactness assessment method of high-temperature pipe bump joint
CN107463737A (en) * 2017-07-25 2017-12-12 中国石油大学(北京) A kind of computational methods and device of fluid pipeline leakage rate
WO2018086160A1 (en) * 2016-11-09 2018-05-17 北京工业大学 Rough surface-based three-dimensional contact stiffness calculation method for spur gear
EP3372954A1 (en) * 2017-03-09 2018-09-12 Kabushiki Kaisha Toyota Chuo Kenkyusho Arithmetic unit, method and program for computing a contact condition between two surfaces
CN109241598A (en) * 2018-08-24 2019-01-18 大连理工大学 A kind of screw thread based on fine motion frictional theory loosens analysis method
CN111914346A (en) * 2020-06-17 2020-11-10 成都飞机工业（集团）有限责任公司 Calculation method for simulating leakage amount
CN112257315A (en) * 2020-10-22 2021-01-22 华中科技大学 Design method of fuel cell sealing structure with safety leakage rate as target

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1748371A1 (en) * 2005-07-26 2007-01-31 Denso Corporation Apparatus and method for determining patterns of damage being caused in rolling contact element
WO2009135639A1 (en) * 2008-05-05 2009-11-12 Aktiebolaget Skf Determining hydrostatic leakage
WO2018086160A1 (en) * 2016-11-09 2018-05-17 北京工业大学 Rough surface-based three-dimensional contact stiffness calculation method for spur gear
EP3372954A1 (en) * 2017-03-09 2018-09-12 Kabushiki Kaisha Toyota Chuo Kenkyusho Arithmetic unit, method and program for computing a contact condition between two surfaces
CN107229778A (en) * 2017-05-15 2017-10-03 武汉工程大学 The compactness assessment method of high-temperature pipe bump joint
CN107463737A (en) * 2017-07-25 2017-12-12 中国石油大学(北京) A kind of computational methods and device of fluid pipeline leakage rate
CN109241598A (en) * 2018-08-24 2019-01-18 大连理工大学 A kind of screw thread based on fine motion frictional theory loosens analysis method
CN111914346A (en) * 2020-06-17 2020-11-10 成都飞机工业（集团）有限责任公司 Calculation method for simulating leakage amount
CN112257315A (en) * 2020-10-22 2021-01-22 华中科技大学 Design method of fuel cell sealing structure with safety leakage rate as target

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
反应堆安全壳密封结构泄漏机理与预测模型的研究;黄晓明;李骏;许国良;成卓;吕祥奎;;核动力工程(03);全文 *
基于赫兹理论的弹性磨具磨抛M300钢表面参数模型研究;吴晓君;刘睿平;于兴展;武倩;;表面技术;20150620(06);全文 *
基于逾渗理论的机械密封界面静态泄漏预测方法;嵇正波等;摩擦学学报;第第37卷卷(第第6期期);734-742 *
嵇正波 ; 孙见君 ; 陆建花 ; 马晨波 ; 於秋萍 ; .基于逾渗理论的机械密封界面静态泄漏预测方法.摩擦学学报.2017,(06),全文. *
无扩口导管拧紧力矩对其密封性能的影响;郑世伟;丁晓;梁红琴;彭炳康;祝孟豪;张永建;;润滑与密封(05);全文 *

Also Published As

Publication number Publication date
CN113076606A (en) 2021-07-06

Similar Documents

Publication Publication Date Title
Etsion Modeling of surface texturing in hydrodynamic lubrication
CN113076606B (en) Aviation pipeline flaring joint leakage rate calculation method and system considering contact deformation
CN104858189A (en) Variable diameter pig suitable for oil and gas transmission variable diameter pipelines and technology method
CN113722956A (en) Method for predicting assembly tightness of flaring type guide pipe
CN112553607A (en) Outer ring anti-raceway phosphating device for conical bearing
CN106678476A (en) Sleeve-type dynamic seal compensator
CN113028299A (en) Gas-liquid equivalent detection method and system for micro leakage of aviation hydraulic pipeline
RU2331014C2 (en) Method of pipeline repair
CN208090134U (en) Telescoping tube
Franchini et al. Use of Torricelli's equation for describing leakages in pipes of different elastic materials, diameters and orifice shape and dimensions
CN113531221B (en) Composite embedded pipe and processing method
CN212779894U (en) Pressure chamber experimental device
CN205120507U (en) Expansion joint's hydrostatic pressing testing arrangement
CN203376000U (en) Differential pressure type uniform-velocity flow sensor
CN112943483A (en) Double-channel redundant sealing device of liquid rocket engine
Goltsberg et al. Experimental Study of the Sealing Performance of Metal on Polymer Conical Seals
CN207848688U (en) Telescoping tube
Wang et al. Microscale flow field analysis and flow prediction model exploration of dry gas seal
CN110925295A (en) Slewing bearing and oil injection process thereof
CN212059389U (en) A back pipe fixing device for different experimental survey holes
CN213018045U (en) Device for observing liquid behind valve
CN221034417U (en) Quick connector and flowmeter
CN219625000U (en) Device for simulating pipeline leakage
CN108150649A (en) A kind of design method of the electrical general connector sealing ring of underwater wet-type
Wang et al. Performance of the Internal Mixer’s end Face Mechanical Seal with Isosceles Right Triangle Textures

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant