CN-121168028-B - Structural vibration displacement prediction method based on tube bundle segment power spectrum conversion

CN121168028BCN 121168028 BCN121168028 BCN 121168028BCN-121168028-B

Abstract

The invention provides a structural vibration displacement prediction method based on tube bundle segment power spectrum conversion, and relates to the field of structural dynamic response prediction. The method comprises the steps of S1, obtaining dimensionless power spectrum density, S2, equally dividing the length of a tube bundle, calculating the self spectrum density of each tube bundle through the dimensionless power spectrum density, S3, performing inverse Fourier transform on the self spectrum density of each tube bundle to generate time domain force, and S4, generating displacement response of the tube bundle by using matlab program and adopting a transient integration method. The method solves the key problem that the measurement precision and engineering applicability are difficult to unify in the prior art, realizes accurate calculation of the vibration displacement of the tube bundle, remarkably improves the precision and calculation stability of the structure vibration displacement prediction, and provides a reliable technical means for flow-induced vibration analysis of the tube bundle in a complex industrial scene.

Inventors

ZHU GUORUI
CHEN ZHENGQIAO
TAN WEI
SUN ZHENGRUI

Assignees

天津大学

Dates

Publication Date: 20260508
Application Date: 20250905

Claims (4)

1. The structural vibration displacement prediction method based on tube bundle segment power spectrum conversion is characterized by comprising the following steps of: S1, acquiring dimensionless power spectrum density; s2, equally dividing the length of the tube bundle, and calculating the self-spectrum density of each section of tube bundle through dimensionless power spectrum density; s3, performing inverse Fourier transform on the self-spectrum density of each section of tube bundle to generate time domain force; S4, generating displacement response of the tube bundle by using a matlab program and adopting a transient integration method; The specific content of the step S2 is as follows: step S201, equally dividing the length of the tube bundle into a plurality of sections, and assuming that each section of tube bundle is a rigid section, the specific expression is as follows: ; Wherein, the Representing an integration length; Representing the length of the tube bundle; Representing the number of tube bundle segments; Step S202, calculating the self-spectrum density of each section of tube bundle The specific expression is: ; Wherein, the Representing modal correlation coefficients; Representing a tube bundle reference length; representing the tube diameter of the tube bundle; Representing a reference diameter; 、 representing a two-phase flow normalization factor; Representing the frequency; Representing dimensionless power spectral density.
2. The method for predicting structural vibration displacement based on tube bundle segment power spectrum conversion according to claim 1, wherein the specific content of step S3 is as follows: Step S301, self-spectrum density of each tube bundle Performing inverse Fourier transform to generate a plurality of sections of uncorrelated time domain forces The specific expression is: ; Wherein, the Represent the first A frequency; Representing frequency Self spectral density at; The frequency interval is represented by a frequency interval, ; Representing the time; Represent the first The segment bundles are at frequency A random phase at; step S302, calculating a correlation coefficient between time domain forces of each section of tube bundle Verifying whether correlation exists between time domain forces of different sections of tube bundles, wherein the specific expression is as follows: ; Wherein, the Represent the first Segment bundle time domain forces; Represent the first Segment bundle time domain forces; Represent the first Segment tube bundle time domain force and th Covariance between segment bundle time domain forces; Represent the first The value of the autocorrelation function of the time domain force of the segment tube bundle at zero time delay, namely A mean square value of the segment bundle time domain force; Represent the first The value of the autocorrelation function of the time domain force of the segment tube bundle at zero time delay, namely Mean square of the segment bundle time domain forces.
3. The method according to claim 1, wherein in step S4, the displacement response of the tube bundle includes a displacement response curve and a root mean square of the displacement.
4. The method for predicting structural vibration displacement based on tube bundle segment power spectrum conversion according to claim 1, wherein in step S4, the specific expression of the root mean square of the displacement is: ; Wherein, the Representing the root mean square of the displacement; Representation of A time-of-day displacement response value; indicating the total number of time steps.

Description

Structural vibration displacement prediction method based on tube bundle segment power spectrum conversion Technical Field The invention relates to the field of structural dynamic response prediction, in particular to a structural vibration displacement prediction method based on tube bundle segment power spectrum conversion. Background Currently, in industrial equipment such as heat exchangers, fluid-induced tube bundle vibration problems are increasingly prominent, and especially fatigue damage caused by fluid disturbances has become a critical factor affecting equipment safety and reliability. The prior art mainly analyzes tube bundle vibration by modeling loading forces through the overall power spectrum, but this approach ignores the force timing independence between different segments, which may lead to an underestimation of the actual response. In the aspect of tube bundle vibration displacement measurement, the mainstream method is based on random vibration theory. The core of the theory is the root mean square equation of tube bundle deflection, which is derived from the equation of motion of the beam forced vibration, and the final applicable form is proposed by PETTIGREW and Gorman for cross-flow conditions. However, this method has obvious limitations that, on one hand, it cannot provide a displacement timing diagram or a displacement maximum value, which limits further analysis and evaluation, and on the other hand, it relies on a large number of assumptions and simplifications in the calculation process, resulting in errors in the root mean square calculation result, and the calculation method is single and lacks flexibility. Therefore, development of a new method capable of improving the calculation accuracy and meeting the actual requirements of engineering is needed to solve the defects of the prior art. Disclosure of Invention The invention aims to provide a structural vibration displacement prediction method based on tube bundle segment power spectrum conversion, which solves the problem that the existing vibration calculation method is difficult to effectively unify between measurement precision and engineering applicability. In order to achieve the above purpose, the invention provides a structural vibration displacement prediction method based on tube bundle segment power spectrum conversion, which comprises the following steps: S1, acquiring dimensionless power spectrum density; s2, equally dividing the length of the tube bundle, and calculating the self-spectrum density of each section of tube bundle through dimensionless power spectrum density; s3, performing inverse Fourier transform on the self-spectrum density of each section of tube bundle to generate time domain force; And S4, generating displacement response of the tube bundle by using a matlab program and adopting a transient integration method. Preferably, the specific content of step S2 is: step S201, equally dividing the length of the tube bundle into a plurality of sections, and assuming that each section of tube bundle is a rigid section, the specific expression is as follows: wherein Deltax represents the integrated length, L represents the length of the tube bundle, N represents the number of tube bundle segments; step S202, calculating the self-spectral density phi F (f) of each section of tube bundle, wherein the specific expression is as follows: Wherein a represents a modal correlation coefficient, L 0 represents a tube bundle reference length, D represents a tube bundle tube diameter, D 0 represents a reference diameter, p 0、f0 represents a two-phase flow normalization factor, and f represents frequency; Representing dimensionless power spectral density. Preferably, the specific content of step S3 is: step S301, performing inverse fourier transform on the self-spectrum density Φ F (F) of each segment of tube bundle, and generating a plurality of segments of uncorrelated time domain forces F i (t), where the specific expression is as follows: Wherein f k denotes the kth frequency, Φ F(fk) denotes the self-spectral density at frequency f k, Δf denotes the frequency interval, Δf=f k+1-fk, t denotes the time of day, θ ik denotes the random phase of the ith tube bundle at frequency f k; Step S302, calculating a correlation coefficient C ij between each segment of tube bundle time domain force, and verifying whether there is a correlation between different segments of tube bundle time domain forces, where a specific expression is as follows: Wherein F i (t) represents the ith tube bundle time domain force, F j (t) represents the jth tube bundle time domain force, E < F i(t)Fj (t) > represents the covariance between the ith tube bundle time domain force and the jth tube bundle time domain force, E < F i(t)Fi (t) > represents the value of the autocorrelation function of the ith tube bundle time domain force at zero delay, namely the mean square value of the ith tube bundle time domain force, and E < F j(t)Fj (t) > repres