Stability Derivatives in a Parallel Triangular Tube Bundle Subject to Cross-Flow at Moderated Reynolds Number

2013 ◽  
Author(s):  
C. Charreton ◽  
C. Béguin ◽  
R. Yu ◽  
S. Etienne
Keyword(s):  
Reynolds Number ◽  
Tube Bundle ◽  
Lift Coefficient ◽  
Cross Flow ◽  
Central Cylinder ◽  
Flow Conditions ◽  
Stability Derivatives ◽  
The Stability ◽  
The Moment

This paper deals with the numerical and experimental determination of stability derivative inside a parallel triangular tube bundle for pitch Reynolds number Rep ∈ [60 3.104]. The present work focuses on the derivative of the lift coefficient, in the direction transverse to the flow, of the central cylinder for Rep ∈ [60 1.2.103]. We consider a viscous and incompressible flow for both approaches. First, experiments were done in a loop containing an adjustable central cylinder set with strain gauges to indirectly measure the lift derivative, via the moment of lift. Reynolds number is controlled by using a few glycerin solutions with different viscosities. In parallel, same flow conditions were simulated within 2D simulations. Comparisons were performed between experimental and numerical results. A critical Reynolds was found where the stability derivative seems to cross zero. This fact raises a question about applicability of quasi-steady model for fluidelastic instability.

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.

Determination of Stability Derivatives by Impulse-Response Techniques

1977 ◽  
Vol 14 (02) ◽  
pp. 265-275
Author(s):  
Carl A. Scragg
Keyword(s):  
Memory Effect ◽  
Impulse Response ◽  
Traditional Method ◽  
Equations Of Motion ◽  
Experimental Results ◽  
Regular Motion ◽  
Stability Derivatives ◽  
The Stability ◽  
Derivatives Of

This paper presents a new method of experimentally determining the stability derivatives of a ship. Using a linearized set of the equations of motion which allows for the presence of a memory effect, the response of the ship to impulsive motions is examined. This new technique is compared with the traditional method of regular-motion tests and experimental results are presented for both methods.

Determination of the Fluid-Elastic Stability Threshold in the Presence of Turbulence: A Theoretical Study

1989 ◽  
Vol 111 (4) ◽  
pp. 407-419 ◽  
Author(s):  
J. H. Lever ◽  
G. Rzentkowski
Keyword(s):  
Theoretical Study ◽  
Cross Flow ◽  
Elastic Stability ◽  
Mass Ratio ◽  
Response Curves ◽  
Stability Threshold ◽  
Pitch Ratio ◽  
The Stability ◽  
Experimental Findings

A model has been developed to examine the effect of the superposition of turbulent buffeting and fluid-elastic excitation on the response of a single flexible tube in an array exposed to cross-flow. The modeled response curves for a 1.375-pitch ratio parallel triangular array are compared with corresponding experimental data for the same array; reasonably good qualitative agreement is seen. Turbulence is shown to have a significant effect on the determination of the stability threshold for the array, with increasing turbulent buffeting causing a reduction in the apparent critical velocity. The dependence of turbulence response on mass ratio is also found to yield a slight independence between mass and damping parameters on stability threshold estimates, which may account for similar experimental findings. Different stability criteria are compared, and an attempt is made to provide some guidance in the interpretation of response curves from actual tests.

Bubble departure characteristics in a horizontal tube bundle under cross flow conditions

2018 ◽  
Vol 100 ◽  
pp. 143-154 ◽  
Author(s):  
Parul Goel ◽  
Arun K. Nayak ◽  
Mihir K. Das ◽  
Jyeshtharaj B. Joshi
Keyword(s):  
Tube Bundle ◽  
Cross Flow ◽  
Horizontal Tube ◽  
Flow Conditions

Self-Excited Vibration of Cross-Shaped Tube Bundle in Cross Flow

2002 ◽  
Author(s):  
Fumio Inada ◽  
Takashi Nishihara ◽  
Akira Yasuo ◽  
Ryo Morita ◽  
Akihiro Sakashita ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Large Scale ◽  
Tube Bundle ◽  
Cross Flow ◽  
Small Scale ◽  
Design Guideline ◽  
Shaped Tube ◽  
Excited Vibration ◽  
Scale Test ◽  
Flexible Tubes

Cross-shaped tube bundle is proposed for a lower plenum structure in a next generation LWR. Vibration response of cross-shaped tube bundle in cross flow has been measured in water tunnel tests. First, small-scale test was conducted. Tests were conducted with 3×3 flexible tubes as well as single flexible tube in rigid tube bundle. The flexible tubes could vibrate in lift, drag, and torsional direction. The effect of arrangements of tube bundle and the natural frequency ratio of bending and torsional vibrations were considered. Second, a large-scale test was conducted for only one case to check the effect of Reynolds number, in which Reynolds number was 10 times larger than that of small-scale test. In all the cases, large amplitude vibration could appear when the flow velocity became larger than a critical value, and a self-excited vibration was found to occur. The nondimensional critical gap velocity of the large-scale test agreed well with that of the small-scale test, which suggested that the effect of Reynolds number was not so large. A design guideline to prevent self-excited vibration was proposed for cross-shaped tube bundle.

Effect of Angle of Attack on Fluidelastic Instability of a Rotated Triangular Tube Bundle

2007 ◽  
Author(s):  
A. Khalvatti ◽  
N. W. Mureithi ◽  
M. J. Pettigrew
Keyword(s):  
Hydraulic Resistance ◽  
Tube Bundle ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Point Of View ◽  
Steam Generators ◽  
Fluidelastic Instability ◽  
Shell And Tube ◽  
The Stability ◽  
Resistance Forces

In the operation of shell-and-tube heat exchangers, vibration of the tubes can be induced by fluid flowing over the tube array in cross flow. The region of concern in Steam Generators (SG) is the upper most U-bend region where the flow crosses a large number of tubes which can cause significant hydraulic resistance. This hydraulic resistance forces the flow to change direction. From a fluidelastic instability point of view, the tube bundle is excited by oblique cross flow. The purpose of this paper is to examine the instability phenomena in a rotated triangular tube bundle subjected to oblique single phase cross flow. In this present work tests are conducted in a wind tunnel on a rotated triangle tube array. Fluidelastic instability results are in agreement with what was expected. The results show that fluidelastic instability is strongly dependent on the angle of attack. The results also show that, generally, the elimination of bundle flexibility in the direction transverse to the flow, greatly affects the stability behavior of the array.

Determination of Maneuvering Properties in Shallow Water by Impulse Response Techniques

1982 ◽  
Vol 26 (01) ◽  
pp. 1-15
Author(s):  
Douglas J. Loeser
Keyword(s):  
Shallow Water ◽  
Systematic Investigation ◽  
Qualitative Description ◽  
Forward Speed ◽  
Regular Motion ◽  
Ship Maneuvers ◽  
Stability Derivatives ◽  
The Stability ◽  
Zero Frequency

This work presents the results of a systematic investigation of the effects of shallow water, forward speed, and block coefficient on maneuvering properties. Stability derivatives are experimentally determined using a recently developed impulse procedure. The determination of the stability derivatives at zero frequency is examined. Experimental results are compared with similar results from regular motion tests. Numerical computation of ship maneuvers in shallow water using the experimentally determined motion derivatives gives a qualitative description of the effects of shallow water and depth.

A numerical study of heat transfer in the in-line tube bundle under pulsating fluid flow conditions

Vestnik IGEU ◽  
2019 ◽  
pp. 12-21
Author(s):  
A.I. Khaibullina ◽  
A.R. Khairullin
Keyword(s):  
Heat Transfer ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Tube Bundle ◽  
Cross Flow ◽  
Pulsating Flow ◽  
Operating Parameters ◽  
Flow Conditions ◽  
Study Results ◽  
Shell And Tube

Shell-and-tube heat exchangers are widely used in different industries. Even a small increase in the efficien-cy of shell-and-tube heat exchangers can lead to significant energy savings. One of the ways to improve the efficiency of shell-and-tube heat exchangers is the use of pulsating flows for the enhancement of heat ex-change. Despite the fact that heat transfer in the tube bundle cross flow in steady-state conditions has been studied quite well, there is limited data on heat transfer in pulsating flow, which means that the problem of finding regularities of heat transfer with pulsating flows in tube bundles is still important. The work employs the incompressible Reynolds averaged Naviere-Stokes (URANS) equations and the continuity equation. Heat transfer is described by the convective heat transfer (Fourier-Kirchhoff) equation. The calculations are performed using Ansys Fluent. A numerical study has been conducted of the effects of forced asymmet-rical pulsating flow on heat exchange in in-line tube bundle cross-flow conditions. In the numerical experi-ment the Reynolds number Re ranged from 1000 to 2000, the relative pulsating amplitude A/D – from 1 to 2, the Strouhal number Sh – from 0,77 to 1,51, the Prandtl number and the duty cycle had fixed values: Pr = 7,2,  = 0,25. The relative transverse and longitudinal pitch was s1,2/D = 1,3. It has been found that pulsating flows lead to the enhancement of heat transfer in the whole range of the studied operating parameters. An increase in A/D and Sh leads to bigger Nusselt number Nu. An increase in the Re number leads to a de-crease in the Nu ratio in pulsating and steady flow conditions. The general correlation obtained based on the numerical study results can be used to predict heat transfer in a pulsating flow in the range of the studied geometric and operating parameters. More research is needed to predict heat transfer in a wider range of operating parameters and with other tube bundle configurations.

K-1229 Turbulence-Induced Fluid Dynamic Forces Acting on Cross-Shaped Tube Bundle in Cross Flow : Part 2 : Measurement in the High Reynolds Number

2001 ◽  
Vol V.01.1 (0) ◽  
pp. 139-140
Author(s):  
Takashi NISHIHARA ◽  
Nobukazu TANAKA ◽  
Fumio INADA ◽  
Akira YASUO ◽  
Shinichi KAWAMURA ◽  
...  
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Tube Bundle ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Shaped Tube ◽  
Dynamic Forces ◽  
Flow Part ◽  
High Reynolds

scholarly journals Determination of critical flow velocity for tube-bundle with application of numerical investigation method

Energetika ◽  
2016 ◽  
Vol 61 (3-4) ◽  
Author(s):  
Alexey Samolysov ◽  
Saveliy Kaplunov ◽  
Natalia Vales ◽  
Olga Marchevskaya ◽  
Elena Dronova
Keyword(s):  
Mathematical Model ◽  
Numerical Investigation ◽  
Tube Bundle ◽  
Connection Matrix ◽  
Investigation Method ◽  
Elastic Tubes ◽  
Tube Bundles ◽  
The Creation ◽  
The Stability

The work is devoted to the creation and application of mathematical models for the most dangerous oscillation excitation mechanisms of tubes and cylindrical form bluff structures in liquid or gas flow, as well as to the creation of efficient computational methods for description of these models. A numerical investigation method of hydrodynamic forces arising from a  separated flow and tube-bundle oscillations excited by these forces was developed by the authors. The method is based on the  application of created original tube-bundle hydroelastic oscillation excitation in a cross-flow mathematical model. Hydroelastic excitation problem is reduced to the stability analysis of undisturbed state of elastic tubes. Analysis is conducted with the assumption of linearity of the destabilizing forces. On the basis of the mathematical model, the necessary and sufficient condition for the  stability, expressed through the  dimensionless system parameters (mass, damping, velocity), was obtained. Numerical identification of the  linear hydrodynamic connection matrix algorithm for particular tube-bundles was elaborated. Verification of algorithm and programs based on it was performed by results of simulations and available experimental data correlation. A method for determination of a linear hydrodynamic connection matrix for tube-bundles with a regular arrangement of the cross-section was offered. It is based on computation of a relatively small, but sufficient for reliable results, part of the tube-bundle.

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