A Study of the Impact Dynamics of Loosely Supported Heat Exchanger Tubes

1989 ◽  
Vol 111 (4) ◽  
pp. 394-401 ◽  
Author(s):  
H. G. D. Goyder ◽  
C. E. Teh
Keyword(s):  
Heat Exchanger ◽  
Cross Flow ◽  
Excitation Level ◽  
Impact Dynamics ◽  
Heat Exchanger Tube ◽  
Wear Rates ◽  
Strongly Nonlinear ◽  
The Impact ◽  
Loose Support ◽  
Exchanger Tube

Heat exchanger tube bundles may be damaged by vibration induced from the cross flow. This damage generally occurs at the tube supports where the tube is only loosely supported. The loose support results in the tube motion being strongly nonlinear with very complicated dynamics. Some theoretical equations for the tube dynamics and wear rates are investigated by using dimensional analysis, physical modeling and numerical simulations. From the analysis of these equations, some simple formulas are developed which show the influence of excitation level and tube-to-support clearance on the tube response.

Spanwise Correlation of Surface Pressure Fluctuations in Heat Exchanger Tube Arrays

2010 ◽  
Author(s):  
John Mahon ◽  
Paul Cheeran ◽  
Craig Meskell
Keyword(s):  
Heat Exchanger ◽  
Surface Pressure ◽  
Pressure Fluctuations ◽  
Cross Flow ◽  
Fretting Wear ◽  
Heat Exchanger Tube ◽  
Tube Arrays ◽  
Pitch Ratio ◽  
Excitation Mechanisms ◽  
Exchanger Tube

An experimental study of the surface spanwise pressure on a cylinder in the third row of two normal triangular tube arrays (P/d = 1.32 and 1.58) with air cross flow has been conducted. A range of flow velocities were examined. The correlation of surface pressure fluctuations due to various vibration excitation mechanisms along the span of heat exchanger tubes has been assessed. The turbulent buffeting is found to be uncorrelated along the span which is consistent with generally accepted assumptions in previous studies. Vortex shedding and acoustic resonances were well correlated along the span of the cylinder, with correlations lengths approaching the entire length of the cylinder. Jet switching was observed in the pitch ratio of 1.58 and was found to be correlated along the cylinder, although the spatial behaviour is complex. This result suggests that the excitation force used in fretting wear models may need to be updated to include jet switching in the calculation.

Effect of nonlinear cladding stiffness on the stability and Hopf bifurcation of a heat-exchanger tube subject to cross-flow

Meccanica ◽  
2020 ◽  
Vol 55 (1) ◽  
pp. 49-68
Author(s):  
Varun Vourganti ◽  
Ajinkya Desai ◽  
Surya Samukham ◽  
C. P. Vyasarayani
Keyword(s):  
Heat Exchanger ◽  
Hopf Bifurcation ◽  
Cross Flow ◽  
Heat Exchanger Tube ◽  
The Stability ◽  
Exchanger Tube

A Comparative Study of Cross-Flow Induced Vibrations in Heat Exchanger Tube Bundles Using Bond Graph Approach

2005 ◽  
Author(s):  
M. Afzaal Malik ◽  
Badar Rashid ◽  
Shahab Khushnood
Keyword(s):  
Heat Exchanger ◽  
Comparative Study ◽  
Tube Bundle ◽  
Cross Flow ◽  
Bond Graph ◽  
Heat Exchanger Tube ◽  
Flow Induced Vibration ◽  
Study Results ◽  
Tube Bundles ◽  
Exchanger Tube

Flow-induced vibration (FIV) has been a major concern in the nuclear and process industries involving steam generator and heat exchanger tube bundle design. Various techniques and models have been developed and used for the analysis of cross-flow induced vibration of tube bundles. Bond Graph approach has been applied to existing FIV excitation models, followed by a comparative study. Results have been obtained using 20-SIM software. It is expected that the current approach will give a new dimension to the FIV analysis of tube bundles.

Vibration-Induced Wear of Heat Exchanger Tubes

1985 ◽  
Vol 107 (1) ◽  
pp. 61-67 ◽  
Author(s):  
R. D. Blevins
Keyword(s):  
Heat Exchanger ◽  
High Speed ◽  
Impact Wear ◽  
Heat Exchanger Tube ◽  
Metallographic Examination ◽  
Wear Rates ◽  
High Speed Cinematography ◽  
Exchanger Tube ◽  
Temperature Amplitude ◽  
Scanning Electron

An analytical and experimental investigation has been made of the wear of a heat exchanger tube vibrating against a tube support. The purpose of this investigation is to develop a predictive model for onset of tube wear and experimentally investigate the tube dynamics and the wear mechanism. The analytical model is based on impact wear theory. The rate of wear of a tube in forced vibration was measured as a function of temperature, amplitude of vibration, frequency of vibration, material, and environment. Tube-support impact velocity was measured using high-speed cinematography, and metallographic examination of the wear specimens was performed using a scanning electron microscope. The result is an experimentally validated model for onset of wear and experimental data for wear rates.

Fluidelastic Vibration of Heat Exchanger Tube Arrays

1978 ◽  
Vol 100 (2) ◽  
pp. 347-353 ◽  
Author(s):  
H. J. Connors
Keyword(s):  
Heat Exchanger ◽  
Flow Velocity ◽  
Cross Flow ◽  
Test Results ◽  
Excitation Mechanism ◽  
Heat Exchanger Tube ◽  
Flow Test ◽  
Tube Arrays ◽  
Instability Constant ◽  
Exchanger Tube

A basic fluidelastic excitation mechanism, of a type reported in an earlier paper, causes large whirling vibrations of tubes in model arrays when the flow velocity exceeds a critical value. The critical velocity is U = βfnDmoδn/ρoD2 where β, the threshold instability constant is a function of the tube pattern and spacing. Threshold instability constants are given that were obtained from wind tunnel and water tunnel tests on multirow tube arrays in uniform cross flow. Test results are discussed that demonstrate the effects of spanwise variations in flow velocity on fluidelastic whirling for both straight tubes and U-tubes. Design methods are provided for predicting the onset of fluidelastic whirling of heat exchanger tubes on multiple supports when spanwise variations in the cross flow exist.

scholarly journals Dynamics of Cross-Flow Heat Exchanger Tubes With Multiple Loose Supports

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Anwar Sadath ◽  
Harish N. Dixit ◽  
C. P. Vyasarayani
Keyword(s):  
Heat Exchanger ◽  
Flow Velocity ◽  
Galerkin Approximation ◽  
Cross Flow ◽  
Beam Equation ◽  
Critical Flow Velocity ◽  
Flow Heat ◽  
Delay Differential ◽  
The Impact ◽  
Loose Support

Dynamics of cross-flow heat exchanger tubes with two loose supports has been studied. An analytical model of a cantilever beam that includes time-delayed displacement term along with two restrained spring forces has been used to model the flexible tube. The model consists of one loose support placed at the free end of the tube and the other at the midspan of the tube. The critical fluid flow velocity at which the Hopf bifurcation occurs has been obtained after solving a free vibration problem. The beam equation is discretized to five second-order delay differential equations (DDEs) using Galerkin approximation and solved numerically. It has been found that for flow velocity less than the critical flow velocity, the system shows a positive damping leading to a stable response. Beyond the critical velocity, the system becomes unstable, but a further increase in the velocity leads to the formation of a positive damping which stabilizes the system at an amplified oscillatory state. For a sufficiently high flow velocity, the tube impacts on the loose supports and generates complex and chaotic vibrations. The impact loading on the loose support is modeled either as a cubic spring or a trilinear spring. The effect of spring constants and free-gap of the loose support on the dynamics of the tube has been studied.

scholarly journals Cross-Flow-Induced-Vibrations in Heat Exchanger Tube Bundles: A Review

10.5772/35635 ◽  
2012 ◽  
Author(s):  
Shahab Khushnood ◽  
Zaffar Muhammad ◽  
Muhammad Afzaal ◽  
Zafarullah Koreshi ◽  
Muhammad Akram ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Cross Flow ◽  
Heat Exchanger Tube ◽  
Tube Bundles ◽  
Flow Induced Vibrations ◽  
Exchanger Tube
Sign in / Sign up

Export Citation Format

Share Document