scholarly journals Numerical simulation of vortex induced vibration in heat exchanger tube bundle at low Reynolds number

2017 ◽  
Vol 14 (2) ◽  
pp. 77-91
Author(s):  
Asif Khan ◽  
Shahab Khushnood ◽  
Najum Ul Saqib ◽  
Imran Sajid Shahid
Keyword(s):  
Reynolds Number ◽  
Heat Exchanger ◽  
Stokes Equations ◽  
Tube Bundle ◽  
Lift Coefficient ◽  
Flow Analysis ◽  
Cross Flow ◽  
Heat Exchanger Tube ◽  
Number Range ◽  
Exchanger Tube

It is sound recognized that when the tube is forced to vibrate or is naturally excited to sufficient amplitudes by flow-induced forces, cyclones peeling phenomena arises at downstream of a tube which clues to vibration in the tube. Two-dimensional numerical recreation model for the computation of flow induced vibration of heat exchanger tube bundle imperiled to cross- flow is proficient in current research. Computational Fluid Dynamics (CFD) tool, GAMBIT (grid generation) and ANSYS FLUENT (fluid flow analysis) are operated during numerical investigations. k-epsilon model is used to solve the Navier– Stokes equations. Lift coefficient graph derived from analysis is used to predict the vortex shedding frequency using Fast Fourier Transform (FFT). The results of flow rate, Strouhal number, Reduced velocity, Natural frequency of tube as found from the experimental data has been verified numerically for a Reynolds number range of 4.45 × 104<Re <4.65 × 104 . It is concluded that experimental results are well in agreement with the numerical results.

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.

ICONE11-36489 A REVIEW OF HEAT EXCHANGER TUBE BUNDLE VIBRATIONS IN TWO-PHASE CROSS-FLOW

2003 ◽  
Vol 2003 (0) ◽  
pp. 78
Author(s):  
Shahab Khushnood ◽  
Zaffar M. Khan ◽  
Muhammad Afzaal Malik ◽  
Zafarullah Koreshi ◽  
Mahmood Anwar Khan
Keyword(s):  
Heat Exchanger ◽  
Tube Bundle ◽  
Cross Flow ◽  
Heat Exchanger Tube ◽  
Two Phase ◽  
Exchanger Tube

A review of heat exchanger tube bundle vibrations in two-phase cross-flow

2004 ◽  
Vol 230 (1-3) ◽  
pp. 233-251 ◽  
Author(s):  
Shahab Khushnood ◽  
Zaffar M. Khan ◽  
M.Afzaal Malik ◽  
Zafar Ullah Koreshi ◽  
Mahmood Anwar Khan
Keyword(s):  
Heat Exchanger ◽  
Tube Bundle ◽  
Cross Flow ◽  
Heat Exchanger Tube ◽  
Two Phase ◽  
Exchanger Tube

Two-Phase Cross-Flow Excitation of a Normal Square Tube Array: Experiments and Analysis

2002 ◽  
Author(s):  
Paul Feenstra ◽  
David S. Weaver ◽  
Tomomichi Nakamura
Keyword(s):  
Heat Exchanger ◽  
Vortex Shedding ◽  
Single Phase ◽  
Tube Bundle ◽  
Cross Flow ◽  
Scale Model ◽  
Phase Flow ◽  
Heat Exchanger Tube ◽  
Two Phase ◽  
Exchanger Tube

Laboratory experiments were conducted to determine the flow-induced vibration response and fluidelastic stability threshold of a model heat exchanger tube bundle subjected to a cross-flow of refrigerant 11 (R-11). The tube bundle consisted of a normal square array of 12 tubes with outer tube diameters of 7.11 mm and a pitch over diameter ratio of 1.485. The experiments were conducted in a flow loop that was capable of generating single-phase and two-phase cross-flows over a variety of mass fluxes and void fractions. The primary intent of the research was to improve our understanding of the flow-induced vibrations of heat exchanger tube arrays subjected to two-phase cross-flow. Of particular concern was the effect of array pattern geometry on fluidelastic instability. The experimental results are analysed and compared with existing data from the literature using various methods of parameter definition. Comparison of amplitude response in liquid flow with previous results shows a similar occurrence of symmetric vortex shedding that validates the scale model approach in single-phase flow. It was found that the introduction of a small amount of bubbles in the flow disrupted the vortex shedding and thereby caused a significant reduction in streamwise vibration amplitude. The fluidelastic stability thresholds for the present array agree well with results from previous studies. Furthermore, a good collapse of the stability data from various investigations is obtained when the fluid density is defined using the slip model of Feenstra et al. [1] and when an effective two-phase flow velocity is defined using the interfacial velocity model of Nakamura et al. [2].

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.

Recent Design Technologies of Moisture Separator Reheater

2009 ◽  
Author(s):  
Jun Manabe ◽  
Jiro Kasahara ◽  
Toshiki Kojima ◽  
Issaku Fujita
Keyword(s):  
Heat Exchanger ◽  
Nuclear Power ◽  
Tube Bundle ◽  
Current Model ◽  
Temperature Oscillation ◽  
Separation Performance ◽  
Heat Exchanger Tube ◽  
Water Test ◽  
Moisture Separator ◽  
Exchanger Tube

This paper introduces the development of the current model Moisture Separator Reheater (MSR) for nuclear power plant (NPP) turbines, commercially placed in service in the period 1984–1997, focusing on the mist separation performance of the MSR along with drainage from heat exchanger tubes. A method of predicting the mist separation performance was devised first based on the observation of mist separation behaviors under an air-water test, then developed for the application to predict under the steam conditions, followed by the verification in comparison with the actual results of a steam condition test. The instability of tube drainage associated with both sub-cooling and temperature oscillation, which may adversely affect the seal welding of tubes to tube sheet owing to thermal fatigue, was measured on an existing unit both to clarify the behaviors and to develop a method to suppress them. Both methods were applied to current model MSR and the effectiveness of the methods was demonstrated. A new concept MSR for 1,700 MW class APWR units is put in perspective based on the technologies, alongside a multidisciplinary optimum design evaluating the heat exchanger tube bundle.

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.

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