CN113008067B - Prediction method for two-phase flow induced tube bundle vibration in submerged state - Google Patents

Prediction method for two-phase flow induced tube bundle vibration in submerged state Download PDF

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CN113008067B
CN113008067B CN202110152688.5A CN202110152688A CN113008067B CN 113008067 B CN113008067 B CN 113008067B CN 202110152688 A CN202110152688 A CN 202110152688A CN 113008067 B CN113008067 B CN 113008067B
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heat exchange
exchange tubes
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CN113008067A (en
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陈永东
夏春杰
吴晓红
程沛
李雪
王严冬
王林
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Hefei General Machinery Research Institute Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/24—Arrangements for promoting turbulent flow of heat-exchange media, e.g. by plates
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F27/00—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus

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Abstract

The invention discloses a prediction method of two-phase flow induced tube bundle vibration in an immersion state, which judges whether the i-th row of heat exchange tubes is damaged by vibration or not by calculating the total time from generation to rising of bubbles of the i-th row of heat exchange tubes in the immersion state, the gas volume, the effective liquid volume, the total gas content, the effective gas content, the total liquid content, the effective liquid content and the two-phase flow average density of the coverage range of the i-th row of heat exchange tubes, the two-phase flow cross flow speed and the critical flow degree in the gaps of the i-th row of heat exchange tubes, and the periodic vortex amplitude and the turbulent flow buffeting amplitude of the i-th row of heat exchange tubes. The prediction method can be applied to the tube bundle vibration prediction of equipment such as a reboiler, a condenser, an evaporator, a nuclear reactor and the like of a shell-and-tube heat exchanger working in an immersed state, can guide the design of a vibration-resistant structure, and has great practical and reference significance on the structural design and safe operation of the equipment.

Description

Prediction method for two-phase flow induced tube bundle vibration in submerged state
Technical Field
The invention relates to the technical field of tube bundle vibration prediction, in particular to a prediction method of two-phase flow induced tube bundle vibration in an immersed state.
Background
With the continuous development of heat exchange equipment upsizing, the problem of vibration of the fluid induced tube bundle is endless, and the reliable operation of the heat exchange equipment is seriously influenced. For the vibration induced by the single-phase fluid transversely flowing through the straight tube bundle, GB151 and TEMA standards provide a complete and feasible calculation method, however, for equipment such as a reboiler, a condenser, a nuclear reactor and the like of a shell-and-tube heat exchanger in an immersion state, due to the complexity of the actual working conditions of the equipment, too many factors influencing the vibration of the two-phase flow induced tube bundle are provided, the flow parameters of specific positions are different, and the influence of an immersion medium on the vibration of the two-phase flow induced tube bundle is unclear, so that the problem of the two-phase flow induced tube bundle vibration of the immersion type heat exchanger in the prior art is solved, and a system feasible vibration prediction method does not exist, and the vibration-resistant structure design of the equipment is seriously influenced.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a prediction method of two-phase flow induced tube bundle vibration in a submerged state, which can be applied to tube bundle vibration prediction of equipment working in the submerged state, such as a reboiler, a condenser, an evaporator, a nuclear reactor and the like, can guide the design of an anti-vibration structure, and has great practical and reference significance on equipment structure design and safe operation.
In order to achieve the purpose, the invention adopts the following technical scheme that:
a prediction method of two-phase flow induced tube bundle vibration in a submerged state comprises the following steps:
s1, calculating a characteristic factor of vibration of a two-phase flow induction tube bundle, namely an ith row of heat exchange tubes in an immersed state, and specifically comprising the following steps:
s11, the total time t from generation to rising of bubbles of the ith row of heat exchange tubes is calculated as follows:
Figure BDA0002933001030000011
Figure BDA0002933001030000012
t＝1/f；
in the formula, D b Represents the bubble shedding diameter; θ represents a contact angle of the bubble with the wall surface; σ represents the surface tension of the shell-side liquid; rho L Represents the liquid density; rho g Represents the gas density; f represents a frequency; g represents the gravitational acceleration;
s12, gas volume in the coverage range of the ith row of heat exchange tubes in the immersed stateV gi The calculation is as follows:
gas volume flow within the coverage of the No. 1 heat exchange tube
Figure BDA0002933001030000021
Gas volume flow in the coverage range of the No. 2 heat exchange tube
Figure BDA0002933001030000022
Gas volume flow in the coverage range of the ith row of heat exchange tubes
Figure BDA0002933001030000023
Gas volume V in the coverage range of the ith row of heat exchange tubes gi ＝Q gi t；
In the formula, Q g Represents the total gas volume flow; n is 1 The number of the heat exchange tubes in the 1 st row is shown; n is i The number of the ith row of heat exchange tubes is represented; n represents the total number of heat exchange tubes in the heat exchange equipment, and n = n 1 +n 2 +n 3 +…+n i +…；
S13, effective liquid volume V in the coverage range of the ith row of heat exchange tubes in the immersed state Li The calculation is as follows:
V Li ＝Q Li t；
Q Li ＝Q gi ρ g /ρ L ；
in the formula: q Li The effective liquid volume flow in the coverage range of the ith row of heat exchange tubes is represented;
s14, total gas content epsilon in the coverage range of the ith row of heat exchange tubes in the immersed state gii And effective gas content ε gi The calculation is as follows:
Figure BDA0002933001030000024
ε gi ＝V gi /(V gi +V Li )；
in the formula, V i Showing the shell side volume in the coverage range of the ith row of heat exchange tubes;
s15, total liquid content rate epsilon in the coverage range of the ith row of heat exchange tubes in the immersed state Lii And effective liquid content ε Li The calculation is as follows:
Figure BDA0002933001030000025
ε Li ＝V Li /(V gi +V Li )；
s16, average density rho of two-phase flow in the coverage range of the ith row of heat exchange tubes in the immersed state TPi The calculation is as follows:
ρ TPi ＝ρ L ε Li +ρ g ε gi ；
s17, two-phase flow cross flow velocity v in the clearance of the ith row of heat exchange tubes in the immersed state TPi The calculation is as follows:
Figure BDA0002933001030000031
in the formula, F si Representing the total cross section area of the shell pass fluid flow of the ith row of heat exchange tubes; f si (ε gii +ε Lii ) The effective cross section area of the two-phase flow of the ith row of heat exchange tubes is represented;
s18, critical fluidity v in the clearance of the ith row of heat exchange tubes in the immersed state C The calculation is as follows:
Figure BDA0002933001030000032
wherein K represents an instability coefficient; a represents an index; d represents the outer diameter of the heat exchange tube; delta. For the preparation of a coating 1 Represents a logarithmic decay rate; f. of 1 Representing a first order natural frequency of the heat exchange tube; m represents the total mass of the heat exchange tube per unit length;
s19, immersingPeriodic vortex amplitude y of ith row of heat exchange tubes in state s And turbulence buffeting amplitude y t The calculation is as follows:
Figure BDA0002933001030000033
in the formula, C L Represents a lift coefficient;
normalized power spectral density
Figure BDA0002933001030000034
Mass flow rate of two-phase flow of the ith row of heat exchange tubes: w Gi ＝ρ TP v TPi ；
Power spectral density S F ＝NPSD(W Gi d) 2 ；
Figure BDA0002933001030000035
In the formula, C 1 Represents coefficient, C 1 Is 0.4213;
s2, judging whether the ith row of heat exchange tubes are damaged by vibration or not according to the characteristic factor of inducing the ith row of heat exchange tubes to vibrate by the two-phase flow in the immersed state; wherein the categories of vibration include: periodic vortex shedding-induced vibration, turbulent buffeting-induced vibration, and elastic vibration.
In step S2, it is determined whether the i-th row of heat exchange tubes will generate vibration induced by periodic vortex shedding, vibration induced by turbulent buffeting, and elastic vibration, specifically as follows:
s21, the judgment of the vibration induced by the periodic vortex shedding is as follows:
judging the total gas content epsilon of the ith row of heat exchange tubes in the immersed state gii Whether the vortex shedding is larger than or equal to 15 percent or not, if so, the vibration induced by the periodic vortex shedding is avoided; if not, the vibration induced by the periodic vortex shedding is possible to occur, further judgment is needed, and the periodicity of the ith row of heat exchange tubes in the immersed state is judgedAmplitude of swirl y s Whether the external diameter of the heat exchange tube is less than or equal to 0.02 time or not, if so, the vibration induced by the periodic vortex shedding cannot occur, and if not, the vibration induced by the periodic vortex shedding can occur;
s22, the judgment of the vibration induced by the turbulent buffeting is as follows:
judging the turbulence buffeting amplitude y of the ith row of heat exchange tubes in the immersed state t Whether the external diameter d of the heat exchange tube is less than or equal to 0.02 time or not, if so, vibration induced by turbulent flow buffeting cannot occur; if not, vibration induced by turbulent buffeting can occur;
s23, the determination of the elastic vibration is as follows:
judging the two-phase flow cross flow velocity v in the tube clearance of the ith row of heat exchange tubes in the immersed state TPi Whether or not the critical flow velocity v is less than or equal to C If so, elastic vibration cannot occur; if not, elastic vibration will occur.
The invention has the advantages that:
(1) The invention combines the basic principles of bubble dynamics and fluid induced tube bundle vibration, analyzes the fluid flow condition near each row of heat exchange tubes, further analyzes the fluid induced vibration condition of each row of heat exchange tubes, and finally provides a prediction method of two-phase flow induced tube bundle vibration in an immersion state. The prediction method can be applied to the tube bundle vibration prediction of equipment such as a reboiler, a condenser, an evaporator, a nuclear reactor and the like of a shell-and-tube heat exchanger working in an immersed state, can guide the design of a vibration-resistant structure, and has great practical and reference significance on the structural design and safe operation of the equipment.
Drawings
FIG. 1 is a flow chart of a method for predicting two-phase flow induced tube bundle vibration under submerged conditions in accordance with the present invention.
FIG. 2 is a schematic representation of a shell-side medium two-phase flow operating condition.
FIG. 3 is a schematic view of the coverage of the ith row of heat exchange tubes.
Fig. 4 is a schematic view of the clearance between the ith row of heat exchange tubes.
Fig. 5 is an overall schematic view of the steam generator according to the first embodiment.
FIG. 6 is a schematic tube layout diagram of the steam generator according to the first embodiment.
Fig. 7 is a schematic arrangement view of heat exchange tubes of the steam generator according to the first embodiment.
FIG. 8 is a schematic view of a first row of heat exchange tubes of the steam generator according to the first embodiment.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, the method for predicting the vibration of the two-phase flow induced tube bundle in the submerged state of the present invention comprises the following steps:
s1, calculating characteristic factors of two-phase flow induced tube bundle vibration in an immersed state; the characteristic factors for inducing the ith row of heat exchange tubes to vibrate by the two-phase flow in the immersed state comprise: the total time t from generation of bubbles of the ith row of heat exchange tubes to rising in the immersed state; gas volume V in the coverage range of the ith row of heat exchange tubes in the immersed state gi (ii) a Effective liquid volume V in the coverage range of the ith row of heat exchange tubes in the immersed state Li (ii) a Total air content epsilon in the coverage range of the ith row of heat exchange tubes in the immersed state gii And effective gas fraction epsilon gi (ii) a In the range covered by the ith row of heat exchange tubes in the immersed stateTotal liquid content epsilon Lii And effective liquid content ε Li (ii) a Average density rho of two-phase flow in the coverage range of the ith row of heat exchange tubes in the submerged state TPi (ii) a Two-phase flow cross flow velocity v in the clearance of the ith row of heat exchange tubes in the immersed state TPi (ii) a Critical fluidity v in the clearance of the ith row of heat exchange tubes in the immersed state C (ii) a Periodic vortex amplitude y of ith row of heat exchange tubes in immersed state s And turbulence buffeting amplitude y t ；
Wherein, the working state of the shell pass medium two-phase flow is shown in figure 2; two-phase flow refers to gas and liquid phases; the shell pass refers to a channel outside the heat exchange tube and a part communicated with the channel; shell pass media refers to media circulating in the shell pass, such as water, steam, and the like;
s11, calculating the total time t from bubble generation to rising of the ith row of heat exchange tubes in the immersed state as follows:
Figure BDA0002933001030000061
Figure BDA0002933001030000062
t＝1/f；
in the formula, D b Represents a bubble shedding diameter; θ represents a contact angle of the bubble with the wall surface; σ represents the surface tension of the shell-side liquid; rho L Represents the liquid density; rho g Represents the gas density; f represents a frequency; g represents the gravitational acceleration;
s12, regarding the gas volume V in the coverage range of the ith row of heat exchange tubes in the immersed state gi The calculation of (c) is as follows:
gas volume flow within the coverage of the No. 1 heat exchange tube
Figure BDA0002933001030000063
Gas volume flow in the coverage range of the No. 2 heat exchange tube
Figure BDA0002933001030000064
Gas volume flow in the coverage range of the ith row of heat exchange tubes
Figure BDA0002933001030000065
Gas volume V within the coverage range of the ith row of heat exchange tubes gi ＝Q gi t；
In the formula, Q g Represents the total volume flow of gas; n is a radical of an alkyl radical 1 The number of the heat exchange tubes in the 1 st row is shown; n is i The number of the ith row of heat exchange tubes is represented; n represents the total number of heat exchange tubes in the heat exchange equipment, and n = n 1 +n 2 +n 3 +…+n i +…；
Wherein, the coverage range of the ith row of heat exchange tubes is shown in FIG. 3;
s13, regarding the effective liquid volume V in the coverage range of the ith row of heat exchange tubes in the immersed state Li The calculation of (a) is as follows:
V Li ＝Q Li t；
Q Li ＝Q gi ρ g /ρ L ；
in the formula: q Li The effective liquid volume flow in the coverage range of the ith row of heat exchange tubes is represented;
s14, regarding the total gas content epsilon in the coverage range of the ith row of heat exchange tubes in the immersed state gii And effective gas fraction epsilon gi The calculation of (a) is as follows:
Figure BDA0002933001030000066
ε gi ＝V gi /(V gi +V Li )；
in the formula, V i Showing the shell side volume in the coverage range of the ith row of heat exchange tubes;
s15, regarding the total liquid content epsilon in the coverage range of the ith row of heat exchange tubes in the immersed state Lii And effective liquid content ε Li Calculation, as follows:
Figure BDA0002933001030000071
ε Li ＝V Li /(V gi +V Li )；
s16, regarding the average density rho of the two-phase flow in the coverage range of the ith row of heat exchange tubes in the submerged state TPi The calculation of (c) is as follows:
ρ TPi ＝ρ L ε Li +ρ g ε gi ；
s17, regarding the two-phase flow cross flow velocity v in the clearance of the ith row of heat exchange tubes in the immersed state TPi The calculation of (a) is as follows:
Figure BDA0002933001030000072
in the formula, F si Representing the total cross section area of the shell pass fluid flow of the ith row of heat exchange tubes; f si (ε gii +ε Lii ) The effective cross section area of the two-phase flow of the ith row of heat exchange tubes is represented;
wherein, the clearance of the ith row of heat exchange tubes is shown in FIG. 4;
s18, regarding the critical fluidity v in the clearance of the ith row of heat exchange tubes in the immersed state C The calculation of (a) is as follows:
Figure BDA0002933001030000073
wherein K represents an instability coefficient; a represents an index; d represents the outer diameter of the heat exchange tube; delta 1 Represents a logarithmic decay rate; f. of 1 Representing a first-order natural frequency of the heat exchange tube; m represents the total mass of the heat exchange tube per unit length;
s19, regarding the periodic vortex amplitude y of the ith row of heat exchange tubes in the immersed state s And turbulence buffeting amplitude y t The calculation of (a) is as follows:
Figure BDA0002933001030000074
in the formula, C L Represents a lift coefficient;
normalized power spectral density
Figure BDA0002933001030000075
Mass flow rate of two-phase flow of the ith row of heat exchange tubes: w Gi ＝ρ TP v TPi ；
Power spectral density S F ＝NPSD(W Gi d) 2 ；
Figure BDA0002933001030000081
In the formula, C 1 Represents coefficient, C 1 Is 0.4213;
s2, predicting whether the ith row of heat exchange tubes can be damaged by vibration or not according to the characteristic factor of the two-phase flow in the immersed state for inducing the ith row of heat exchange tubes to vibrate; wherein the categories of vibration include: vibration induced by periodic vortex shedding, vibration induced by turbulent buffeting, and elastic vibration;
s21, the judgment of the vibration induced by the periodic vortex shedding is as follows:
judging whether the total gas content of the ith row of heat exchange tubes in the immersed state is more than or equal to 15%, if so, not generating vibration induced by periodic vortex shedding; if not, the vibration induced by the periodic vortex shedding is possible, further judgment is needed, whether the periodic vortex amplitude of the ith row of heat exchange tubes in the immersed state is less than or equal to 0.02 time of the outer diameter of the heat exchange tubes is judged, if yes, the vibration induced by the periodic vortex shedding is avoided, and if not, the vibration induced by the periodic vortex shedding is avoided;
s22, the judgment of the vibration induced by the turbulent buffeting is as follows:
judging whether the turbulent buffeting amplitude of the ith row of heat exchange tubes in the immersed state is less than or equal to 0.02 time of the outer diameter of the heat exchange tubes, if so, generating no vibration induced by turbulent buffeting; if not, vibration induced by turbulent buffeting can occur;
s23, the determination of the elastic vibration is as follows:
judging whether the two-phase flow cross flow velocity in the tube gap of the ith row of heat exchange tubes in the immersed state is less than or equal to the critical flow velocity, if so, generating no elastic vibration; if not, elastic vibration can occur;
the first embodiment,
The steam generator in a certain device is shown in figure 5, the tube distribution diagram and the arrangement form of the heat exchange tubes are shown in figures 6 and 7, and the operating conditions of the tube side and the shell side are shown in the following table 1. Under the operating condition, the two-phase flow tube bundle induces vibration, the joints of the heat exchange tubes and the tube plates are leaked, and the first row blocks 3 heat exchange tubes, as shown in figure 8.
Figure BDA0002933001030000082
Figure BDA0002933001030000091
TABLE 1 operating conditions
Taking the row 1 heat exchange tube as an example, according to the prediction method of the two-phase flow induced tube bundle vibration under the immersion state, the situation of the two-phase flow induced tube bundle vibration is analyzed, and the method comprises the following steps:
s1, calculating a characteristic factor of two-phase flow induced vibration of a row 1 heat exchange tube in an immersed state;
s11, calculating the total time t from generation to rising of bubbles of the 1 st row of heat exchange tubes in the immersed state:
Figure BDA0002933001030000092
Figure BDA0002933001030000093
t＝1/f；
wherein θ =48 °; σ =0.02618N/m; rho L ＝798.37kg/m 3 ；ρ g ＝19.33kg/m 3 ；g＝9.8m/s 2 ；
Calculated, t =0.0245s;
s12, calculating the gas volume V in the coverage range of the 1 st row of heat exchange tubes in the immersed state g1 ：
Gas volume flow within the coverage of the No. 1 heat exchange tube
Figure BDA0002933001030000094
Gas volume V within the coverage of the 1 st row of heat exchange tubes g1 ＝Q g1 t；
In the formula, Q g ＝1862.39m 3 /h；n 1 =6; this example is a U-tube, n =1510;
is calculated to obtain V g1 ＝5.04×10 -5 m 3 ；
S13, calculating the effective liquid volume V in the coverage range of the 1 st row of heat exchange tubes in the immersed state L1 ：
V L1 ＝Q L1 t；
Q L1 ＝Q g1 ρ g /ρ L ；
Is calculated to obtain V L1 ＝1.221×10 -6 m 3 ；
S14, respectively calculating the total gas content epsilon in the coverage range of the 1 st row of heat exchange tubes in the immersed state g11 And effective gas content ε g1 ：
Figure BDA0002933001030000095
ε g1 ＝V g1 /(V g1 +V L1 )；
In the formula, V 1 ＝0.0594m 3 ；
Is calculated to obtain ∈ g11 ＝0.08％；ε g1 ＝97.6％；
S15, respectively calculating the total liquid content epsilon in the coverage range of the 1 st row of heat exchange tubes in the immersed state L11 And effective liquid content ε L1 ：
Figure BDA0002933001030000101
ε L1 ＝V L1 /(V g1 +V L1 )；
Is calculated to obtain ∈ L11 ＝0.0021％；ε L1 ＝2.4％；
S16, calculating the average density rho of the two-phase flow in the coverage range of the 1 st row of heat exchange tubes in the immersed state TP1 ：
ρ TP1 ＝ρ L ε L1 +ρ g ε g1 ；
Is calculated to obtain rho TP1 ＝37.74kg/m 3 ；
S17, calculating the two-phase flow transverse flow velocity v in the gap of the 1 st row of heat exchange tubes in the immersed state TP1 ：
Figure BDA0002933001030000102
In the formula, F s1 ＝2.56m 2 ；F s1 (ε g11 +ε L11 )＝0.0022m 2 ；
Is calculated to obtain v TP1 ＝0.95m 2 /s；
S18, calculating the critical fluidity v in the gaps of the heat exchange tubes of the 1 st row in the immersed state C ：
Figure BDA0002933001030000103
Wherein K =3.2; a =0.5; d =25mm; delta 1 ＝0.036；f 1 ＝10.56Hz；m＝1.18kg/m；
V is obtained by calculation C ＝1.14m/s；
S19, respectively calculating the periodic vortex amplitude y of the 1 st row of heat exchange tubes in the immersed state s And turbulence buffeting amplitude y t ：
Figure BDA0002933001030000104
In the formula, C L ＝0.07；
Is calculated to obtain y s ＝0.62mm；
Normalized power spectral density
Figure BDA0002933001030000105
The mass flow rate of the two-phase flow of the heat exchange tube of the 1 st row is as follows: w Gi ＝ρ TP v TPi ；
Power spectral density S F ＝NPSD(W Gi d) 2 ；
Figure BDA0002933001030000111
In the formula, C 1 ＝0.4213；
Is calculated to obtain y t ＝0.028mm；
S2, respectively predicting whether the 1 st row of heat exchange tubes can generate vibration induced by periodic vortex shedding, vibration induced by turbulent buffeting and elastic vibration or not according to characteristic factors of the 1 st row of heat exchange tubes induced by two-phase flow in an immersed state to generate vibration;
s21, judging whether the 1 st row of heat exchange tubes generate vibration induced by periodic vortex shedding or not:
judging whether the total gas content of the 1 st row of heat exchange tubes in the immersed state is more than or equal to 15%, if so, not generating vibration induced by periodic vortex shedding; if not, the vibration induced by the periodic vortex shedding is possible, further judgment is needed, whether the periodic vortex amplitude of the 1 st row of heat exchange tubes in the immersed state is less than or equal to 0.02 time of the outer diameter of the heat exchange tubes is judged, if yes, the vibration induced by the periodic vortex shedding is avoided, and if not, the vibration induced by the periodic vortex shedding is avoided;
because the total gas content epsilon of the 1 st row of heat exchange tubes in the immersed state g11 ＝0.08％，ε g11 <15%, so the 1 st row of heat exchange tubes may generate vibration induced by periodic vortex shedding, and further judgment is needed;
due to the periodic vortex amplitude y of the 1 st row of heat exchange tubes in the immersed state s ＝0.62mm，y s >0.02d, i.e. y s >0.5mm, so that the 1 st row of heat exchange tubes are judged to generate vibration induced by periodic vortex shedding;
s22, judging whether the heat exchange pipe in the 1 st row generates vibration induced by turbulent buffeting:
judging whether the turbulent buffeting amplitude of the 1 st row of heat exchange tubes in the immersed state is smaller than or equal to 0.02 time of the outer diameter of the heat exchange tubes, if so, not generating vibration induced by turbulent buffeting; if not, vibration induced by turbulent buffeting can occur;
turbulent buffeting amplitude y of the heat exchange tube row 1 in the immersed state t ＝0.028mm，y t <0.02d, i.e. y t <0.5mm, so that the 1 st row of heat exchange tubes are judged not to generate vibration induced by turbulence buffeting;
s23, judging whether the 1 st row of heat exchange tubes generate elastic vibration:
judging whether the two-phase flow cross flow velocity in the tube gap of the 1 st row of heat exchange tubes in the immersed state is less than or equal to the critical flow velocity, if so, generating no elastic vibration; if not, elastic vibration can occur;
due to the two-phase flow cross-flow velocity v in the tube clearance of the 1 st row of heat exchange tubes in the submerged state TP1 ＝0.95m 2 (s) critical fluidity v in the gap between the 1 st row of heat exchange tubes in the immersed state C ＝1.14m/s，v TP1 <v C Therefore, the heat exchange tube of the 1 st row in the immersed state can not generate elastic vibration.
According to the analysis, the 1 st row of heat exchange tubes generate vibration induced by periodic vortex shedding, so that leakage phenomena occur at the 1 st row of heat exchange tubes and the tube plates, and the situation is consistent with the actual situation.
The invention is not to be considered as limited to the specific embodiments shown and described, but is to be understood to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Claims (1)

1. A prediction method of two-phase flow induced tube bundle vibration in a submerged state is characterized by comprising the following steps:
s1, calculating a characteristic factor of vibration of a two-phase flow induction tube bundle, namely an ith row of heat exchange tubes in an immersed state, and specifically comprising the following steps:
s11, the total time t from generation to rising of bubbles of the ith row of heat exchange tubes is calculated as follows:
Figure FDA0003956286320000011
Figure FDA0003956286320000012
t＝1/f；
in the formula, D b Represents the bubble shedding diameter; θ represents a contact angle of the bubble with the wall surface; σ represents the surface tension of the shell-side liquid; rho L Represents the liquid density; rho g Represents the gas density; f represents a frequency; g represents the gravitational acceleration;
s12, gas volume V in the coverage range of the ith row of heat exchange tubes in the immersed state gi The calculation is as follows:
gas volume flow within the coverage of the No. 1 heat exchange tube
Figure FDA0003956286320000013
Gas volume flow in the coverage range of the No. 2 heat exchange tube
Figure FDA0003956286320000014
Gas volume flow in the coverage range of the ith row of heat exchange tubes
Figure FDA0003956286320000015
Gas volume V within the coverage range of the ith row of heat exchange tubes gi ＝Q gi t；
In the formula, Q g Represents the total gas volume flow; n is 1 The number of the heat exchange tubes in the 1 st row is shown; n is i The number of the ith row of heat exchange tubes is represented; n represents the total number of heat exchange tubes in the heat exchange equipment, and n = n 1 +n 2 +n 3 +…+n i +…；
S13, effective liquid volume V in the coverage range of the ith row of heat exchange tubes in the immersed state Li The calculation is as follows:
V Li ＝Q Li t；
Q Li ＝Q gi ρ g /ρ L ；
in the formula: q Li The effective liquid volume flow in the coverage range of the ith row of heat exchange tubes is represented;
s14, total gas content epsilon in the coverage range of the ith row of heat exchange tubes in the immersed state gii And effective gas fraction epsilon gi The calculation is as follows:
Figure FDA0003956286320000021
ε gi ＝V gi /(V gi +V Li )；
in the formula, V i Showing the shell side volume in the coverage range of the ith row of heat exchange tubes;
s15, total liquid content rate epsilon in the coverage range of the ith row of heat exchange tubes in the immersed state Lii And effective liquid content ε Li The calculation is as follows:
Figure FDA0003956286320000022
ε Li ＝V Li /(V gi +V Li )；
s16, average density rho of two-phase flow in the coverage range of the ith row of heat exchange tubes in the immersed state TPi The calculation is as follows:
ρ TPi ＝ρ L ε Li +ρ g ε gi ；
s17, two-phase flow cross flow velocity v in the clearance of the ith row of heat exchange tubes in the immersed state TPi The calculation is as follows:
Figure FDA0003956286320000023
in the formula, F si Representing the total cross section area of the shell pass fluid flow of the ith row of heat exchange tubes; f si (ε gii +ε Lii ) The effective cross section area of the two-phase flow circulation of the ith row of heat exchange tubes is shown;
s18, critical fluidity v in the clearance of the ith row of heat exchange tubes in the immersed state C The calculation is as follows:
Figure FDA0003956286320000024
wherein K represents an instability coefficient; a represents an index; d represents the outer diameter of the heat exchange tube; delta. For the preparation of a coating 1 Represents a logarithmic decay rate; f. of 1 Representing a first-order natural frequency of the heat exchange tube; m represents the total mass of the heat exchange tube per unit length;
s19, periodic vortex amplitude y of the ith row of heat exchange tubes in the immersed state s And turbulence buffeting amplitude y t The calculation is as follows:
Figure FDA0003956286320000025
in the formula, C L Represents a lift coefficient;
normalized power spectral density
Figure FDA0003956286320000026
Mass flow rate of two-phase flow of the ith row of heat exchange tubes: w is a group of Gi ＝ρ TPi v TPi ；
Power spectral density S F ＝NPSD(W Gi d) 2 ；
Figure FDA0003956286320000031
In the formula, C 1 Represents coefficient, C 1 Is 0.4213;
s2, judging whether the ith row of heat exchange tubes can be damaged by vibration or not according to the characteristic factor of the two-phase flow induced vibration of the ith row of heat exchange tubes in the immersed state; wherein the categories of vibration include: vibration induced by periodic vortex shedding, vibration induced by turbulent buffeting, and elastic vibration;
in step S2, it is determined whether the i-th row of heat exchange tubes will generate vibration induced by periodic vortex shedding, vibration induced by turbulent buffeting, and elastic vibration, specifically as follows:
s21, the judgment of the vibration induced by the periodic vortex shedding is as follows:
judging the total gas content epsilon of the ith row of heat exchange tubes in the immersed state gii Whether the vortex shedding is larger than or equal to 15 percent or not, if so, the vibration induced by the periodic vortex shedding is avoided; if not, the vibration induced by the periodic vortex shedding is possible to occur, further judgment is needed, and the periodic vortex amplitude y of the ith row of heat exchange tubes in the immersed state is judged s Whether the outer diameter of the heat exchange tube is less than or equal to 0.02 time, if so, vibration induced by periodic vortex shedding cannot occur, and if not, vibration induced by periodic vortex shedding can occur;
s22, the judgment of the vibration induced by the turbulent buffeting is as follows:
judging turbulence buffeting amplitude y of the ith row of heat exchange tubes in the immersed state t Whether or not less thanThe external diameter d of the heat exchange tube is equal to 0.02 time, and if the external diameter d of the heat exchange tube is equal to 0.02 time, turbulence buffeting induced vibration cannot occur; if not, vibration induced by turbulence buffeting can occur;
s23, the determination of the elastic vibration is as follows:
judging the two-phase flow cross flow velocity v in the tube clearance of the ith row of heat exchange tubes in the immersed state TPi Whether or not the critical flow velocity v is less than or equal to C If so, elastic vibration cannot occur; if not, elastic vibration occurs.
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