HEAT EXCHANGER TUBE VIBRATIONThe Effect of Grid Generated Turbulence on the Fluidelastic Instability of Tube Bundles in Cross Flow

1981 ◽  
Author(s):  
B. M. H. Soper
Keyword(s):  
Heat Exchanger ◽  
Cross Flow ◽  
Heat Exchanger Tube ◽  
Tube Bundles ◽  
Fluidelastic Instability ◽  
Exchanger Tube

Fluidelastic Instability of Heat Exchanger Tube Bundles: Review and Design Recommendations

1991 ◽  
Vol 113 (2) ◽  
pp. 242-256 ◽  
Author(s):  
M. J. Pettigrew ◽  
C. E. Taylor
Keyword(s):  
Heat Exchanger ◽  
Flow Velocity ◽  
Point Of View ◽  
Heat Exchanger Tube ◽  
Critical Flow Velocity ◽  
Design Point ◽  
Tube Bundles ◽  
Practical Design ◽  
Fluidelastic Instability ◽  
Exchanger Tube

Fluidelastic instability is the most important vibration excitation mechanism for heat exchanger tube bundles subjected to cross-flow. Most of the available data on this topic have been reviewed from the perspective of the designer. Uniform definitions of critical flow velocity for instability, damping, natural frequency and hydrodynamic mass were used. Nearly 300 data points were assembled. We found that only data from experiments where all tubes are free to vibrate are valid from a design point of view. In liquids, fluid damping is important and should be considered in the formulation of fluidelastic instability. From a practical design point of view, we conclude that fluidelastic instability may be expressed simply in terms of dimensionless flow velocity and dimensionless mass-damping. There is no advantage in considering more sophisticated models at this time. Practical design guidelines are discussed.

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.

Experiments on Tube/Support Interaction With Feedback-Controlled Instability

1992 ◽  
Vol 114 (1) ◽  
pp. 23-32 ◽  
Author(s):  
J. Antunes ◽  
F. Axisa ◽  
M. A. Vento
Keyword(s):  
Heat Exchanger ◽  
Initial Conditions ◽  
Low Flow ◽  
Test Model ◽  
Actual Behavior ◽  
Heat Exchanger Tube ◽  
System Parameters ◽  
Tube Bundles ◽  
Fluidelastic Instability ◽  
Exchanger Tube

Due to tube-support gaps in heat-exchangers, low-frequency modes may develop and become unstable at comparatively low flow velocities. This kind of linear fluidelastic instability results in a negative modal damping value, which is a function of the flow velocity. The response amplitude of the unstable tubes increases steadily until tube-support impact becomes unavoidable. These extremely nonlinear vibratory motions have a high-risk potential, as tube velocities and impact forces can be of very considerable magnitude. This paper reports results on a series of laboratory experiments, intended to validate nonlinear calculations on vibro-impact dynamics of heat exchanger tube bundles under fluidelastic instability. The test model was designed for unidirectional motion and the results obtained should be fairly representative of the actual behavior of the U-bend portion of the heat exchanger tube bundles. The system instability is generated by a velocity feedback loop. This method presents significant advantages due to simplicity of the setup and the controllability of the system parameters, in particular concerning the negative damping ratio of the unstable model. A comparison of experimental and computed system dynamics is presented for several values of the instability growth rate and for various initial conditions of the motion. Influence of other parameters, such as tube-support gap magnitude and gap symmetry, is asserted for realistically ranged values. Results show that several steady motion regimes may arises, depending on the system parameters and initial conditions of the motion, which is a fact of engineering significance. Furthermore, a satisfactory qualitative and quantitative agreement was obtained between theoretical predictions and test data.

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

Modeling and Analysis of Thermal Damping in Heat Exchanger Tube Bundles

2006 ◽  
Author(s):  
Shahab Khushnood ◽  
Muhammad Afzaal Malik ◽  
Zaffar Muhammad Khan ◽  
Ayaz Khan ◽  
Qamar Iqbal ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Nuclear Power ◽  
Cross Flow ◽  
Design Guidelines ◽  
Heat Exchanger Tube ◽  
Flow Induced Vibration ◽  
Modeling And Analysis ◽  
Tube Bundles ◽  
Improved Design ◽  
Exchanger Tube

Most structures and equipment used in nuclear power plant and process plant, such as reactor internals, fuel rods, steam generator tubes bundles, and process heat exchanger tube bundles etc., are subjected to Flow Induced Vibrations (FIV). Costly plant shutdowns have been the source of motivation for continuing studies on cross-flow induced vibration in these structures. Damping has been the target of various research attempts related to FIV in tube bundles. A recent research attempt has shown the usefulness of a phenomenon termed as “thermal damping”. The current paper focuses on the modeling and analysis of thermal damping in tube bundles subjected to cross-flow. It is expected that the present attempt will help in establishing improved design guidelines with respect to damping in tube bundles.

Validation of Flow-Induced Vibration Prediction Codes: PIPO-FE and VIBIC Versus Experimental Measurements

2002 ◽  
Author(s):  
Yingke Han ◽  
Nigel J. Fisher
Keyword(s):  
Heat Exchanger ◽  
Tube Bundle ◽  
Cross Flow ◽  
Heat Exchanger Tube ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Fluidelastic Instability ◽  
Excitation Mechanisms ◽  
Vibration Damage ◽  
Exchanger Tube

The PIPO-FE and VIBIC finite-element computer codes, developed and updated over the past 30 years, are used to calculate heat exchanger tube flow-induced vibration (FIV) response. PIPO-FE includes a linear forced-vibration analysis of heat exchanger tubes subjected to all major flow-induced excitation mechanisms, namely fluidelastic instability, random turbulence-induced excitation and periodic wake shedding. VIBIC is for both linear and non-linear transient dynamic simulations of heat exchanger tubes. When used to simulate a tube with clearance supports (non-linear case), VIBIC calculates tube wear work-rates to aid in the prediction of tube fretting-wear damage. All the excitation mechanisms included in PIPO-FE analyses can be simulated in VIBIC. In addition, VIBIC can model friction forces between a tube and its supports, squeeze film forces produced by the resistance of the fluid opposing the relative motion of the tube and supports, and constant loads. An important application of these codes is the analysis of the susceptibility of a heat exchanger tube to vibration damage. These codes may be used at the design stage to assess a new heat exchanger, or during the operational stage to investigate a tube failure and determine if the damage was caused by vibration. If a vibration problem exists, then the codes can be used to assess the effectiveness of any proposed design modifications. To properly assess tube vibration damage, the codes must predict vibration response accurately. This paper documents the validation process of code predictions against measurements from three flow-induced vibration experiments conducted at Chalk River Laboratories: 1. A single-span cantilever tube bundle subjected to two-phase air-water cross flow; 2. A single-span cantilever tube bundle subjected to single- and two-phase Freon cross flow; and 3. A single-span U-bend tube bundle subjected to single-phase water and two-phase air-water partial cross flow. PIPO-FE and VIBIC code predictions for fluidelastic instability ratio and the response to random turbulence-induced excitation are compared to each other for each of these three experiments. The predictions from the two codes are in good agreement. In addition, the predictions for frequency, damping ratio, fluidelastic instability ratio and the response to random turbulence-induced excitation from both codes are in reasonable agreement with the experimental results.

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.

Acoustic Resonance in Heat Exchanger Tube Bundles—Part I: Physical Nature of the Phenomenon

1987 ◽  
Vol 109 (3) ◽  
pp. 275-281 ◽  
Author(s):  
R. D. Blevins ◽  
M. M. Bressler
Keyword(s):  
Heat Exchanger ◽  
Gas Flow ◽  
Tube Bundle ◽  
Physical Nature ◽  
Transverse Mode ◽  
Acoustic Resonance ◽  
Heat Exchanger Tube ◽  
Sound Levels ◽  
Tube Bundles ◽  
Exchanger Tube

The intense acoustic resonance resulting from gas flow across a bank of heat exchanger tubes in a duct has been investigated experimentally and theoretically. At low gas velocities, the acoustic tone emanating from tube bundles increases in proportion to the flow velocity. When the frequency approaches a bound acoustic transverse mode of the tube bundle, intense sound can result. Sound levels as high as 173 db were measured within the bundle. During resonance, the sound correlates vortex shedding from the tubes and the pressure drop increases in some bundles.

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