Turbulence intensity effect on the axial-flow-induced vibration of an elastic cylinder

2020 ◽  
Vol 99 ◽  
pp. 103144
Author(s):  
Z.Y. Lu ◽  
C.W. Wong ◽  
Y. Zhou
Keyword(s):  
Turbulence Intensity ◽  
Axial Flow ◽  
Elastic Cylinder ◽  
Flow Induced Vibration ◽  
Intensity Effect

Axial-flow-induced vibration of an elastic cylinder placed between two cylinders

2021 ◽  
Vol 106 ◽  
pp. 103371
Author(s):  
P. Wang ◽  
C.W. Wong ◽  
Y. Zhou ◽  
W. Xu
Keyword(s):  
Axial Flow ◽  
Elastic Cylinder ◽  
Flow Induced Vibration

Annular Axial Flow-Induced Vibration of Cylindrical Shells by Flu¨gge’s Shell Theory

2006 ◽  
Author(s):  
Katsuhisa Fujita ◽  
Makoto Katou
Keyword(s):  
Shell Theory ◽  
Stokes Equations ◽  
Cylindrical Shells ◽  
Axial Flow ◽  
Navier Stokes ◽  
Complex Eigenvalue ◽  
Flow Induced Vibration ◽  
Navier Stokes Equations ◽  
Flowing Fluid ◽  
Narrow Passage

The unstable phenomena of thin cylindrical shells subjected to annular axial flow are investigated. In this paper, the analytical model is composed of an elastic axisymmetric shell and a rigid one which are arranged co-axially. Considering the fluid structure interaction between shells and fluid flowing through an annular narrow passage, the coupled equation of motion is derived using Flu¨gge’s shell theory and Navier-Stokes equations. The unstable phenomena of thin cylindrical shells are clarified by using the root locus based on the complex eigenvalue analysis. The numerical parameter studies on the shells with a freely supported end and a rigid one, and with both simply supported ends, are performed taking the dimensins of shells, the characteristics of flowing fluid so on as parameters. The influence of these parameters on the threshold of instability of the coupled vibration between thin cylindrical shells and annular axial flowing fluid are investigated and discussed.

Numerical Investigation of Inlet Turbulence Intensity Effect on a Bluff-Body Stabilized Flame at Near Flame Blow-Off Conditions

2020 ◽  
Author(s):  
Amir Ali Montakhab ◽  
Benjamin Akih Kumgeh
Keyword(s):  
Boundary Conditions ◽  
Numerical Investigation ◽  
Turbulence Intensity ◽  
Bluff Body ◽  
Chemical Species ◽  
Simulation Method ◽  
Intensity Effect ◽  
Flame Instability ◽  
Eddy Simulation ◽  
Lean Conditions

Abstract This paper investigates the effects of the inlet turbulence intensity (ITI) on the dynamics of a bluff-body stabilized flame operating very close to its blow-off condition. This work is motivated by the understanding that more stringent regulations on combustion-generated emission have forced the industry to design combustion systems that operate at very fuel-lean conditions. Combustion at very lean conditions, however, induces flame instability that can ultimately lead to flame extinction. The dynamics of the flame at lean conditions can therefore be very sensitive to boundary conditions. Here, a numerical investigation is conducted using Large Eddy Simulation method to understand the flame sensitivity to inlet turbulence intensity. Combustion is accounted for through the transport of chemical species. The sensitivity to inlet turbulence is assessed by carrying out simulations in which the inlet turbulence is varied in increments of 5%. It is observed that while the inlet intensity of 5% causes blow-off, further increased to 10% preserves a healthy flame on account of greater heat release arising from greater and balanced entrainment of combustible mixtures into the flame zone just behind the bluff-body. This balanced stabilization is again lost as the inlet turbulence intensity is further increased to 15%. Since experimental data pertaining to the topic of this paper are rare, the reasonableness of the combination of models is first checked by validating Volvo propane bluff-body flame, whereby reasonable agreement is observed. This study will advance our understanding of the sensitivity of bluff-body flames to boundary conditions specifically to the inlet turbulent boundary condition at near critical blow-off flame conditions.

A Study on Leakage Flow Induced Vibration From Engineering Viewpoint

2015 ◽  
Author(s):  
Fumio Inada
Keyword(s):  
Damping Ratio ◽  
Axial Flow ◽  
Engineering System ◽  
Dimensional System ◽  
Leakage Flow ◽  
Fluid Inertia ◽  
Flow Induced Vibration ◽  
One Dimensional ◽  
Annular Gap ◽  
Excited Vibration

Leakage-flow-induced vibration for a relatively short gap is studied analytically to provide useful information to design structures that include a leakage flow. The relationship between the analysis of a one-dimensional system and that of an annular gap is explained first. Then, the mechanism of flutter-type instability is reproduced from previous study after correcting an error. Finally, the self-excited vibration potential of an engineering system is shown from sample calculations. It is shown that an axial flow becomes dominant in the short-gap approximation, and in this case, the analysis of a one-dimensional flow can be expanded to that of an annular flow. The result that negative damping can occur in the case of a divergent passage owing to the delay induced by fluid inertia was obtained from a previous study. It was suggested analytically that the damping ratio could become negative and its absolute value could become more than 10% in a system that is frequently encountered in a plant, if the natural frequency decreases. The value could be sufficient to generate self-excited vibration.

Influence of Fluid Viscosity and Structural Specifications on Stability in the Vicinity of Critical Velocity of an Elastic Beam Subjected to Confined Axial Flow

2011 ◽  
Author(s):  
Katsuhisa Fujita
Keyword(s):  
Dynamic Stability ◽  
Critical Velocity ◽  
Axial Flow ◽  
Elastic Beam ◽  
Parameter Study ◽  
Fluid Viscosity ◽  
Structural Damping ◽  
Flow Induced Vibration ◽  
Narrow Passage ◽  
Support Conditions

Evaluation methodologies for the flow-induced vibration of an elastic beam subjected to an axial flow confined in a narrow passage are reported. In this paper, by using the analytical method already proposed by the author, a parameter study is performed on the dynamic stability of an elastic beam subjected to axial flow confined a narrow passage. The effects of support conditions of structures, structural damping, and fluid characteristics on the dynamic stability are clarified. Especially, paying attention on the vicinity of critical velocity, the effects of stabilization or destabilization on flutter and divergence are investigated by changing fluid viscosity and structural damping.

scholarly journals Operational modal analysis of flow-induced vibration of nuclear fuel rods in a turbulent axial flow

2015 ◽  
Vol 284 ◽  
pp. 19-26 ◽  
Author(s):  
B. De Pauw ◽  
W. Weijtjens ◽  
S. Vanlanduit ◽  
K. Van Tichelen ◽  
F. Berghmans
Keyword(s):  
Modal Analysis ◽  
Nuclear Fuel ◽  
Axial Flow ◽  
Operational Modal Analysis ◽  
Flow Induced Vibration ◽  
Fuel Rods ◽  
Nuclear Fuel Rods

scholarly journals Numerical Study on the Characteristics of Pressure Fluctuations in an Axial-Flow Water Pump

2014 ◽  
Vol 6 ◽  
pp. 565061 ◽  
Author(s):  
Zhi-Jun Shuai ◽  
Wan-You Li ◽  
Xiang-Yuan Zhang ◽  
Chen-Xing Jiang ◽  
Feng-Chen Li
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Axial Flow ◽  
Rotation Frequency ◽  
Dominant Frequency ◽  
Water Pump ◽  
Flow Induced Vibration ◽  
Impeller Blade

Flow induced vibration due to the dynamics of rotor-stator interaction in an axial-flow pump is one of the most damaging vibration sources to the pump components, attached pipelines, and equipment. Three-dimensional unsteady numerical simulations were conducted on the complex turbulent flow field in an axial-flow water pump, in order to investigate the flow induced vibration problem. The shear stress transport (SST) k-ω model was employed in the numerical simulations. The fast Fourier transform technique was adopted to process the obtained fluctuating pressure signals. The characteristics of pressure fluctuations acting on the impeller were then investigated. The spectra of pressure fluctuations were predicted. The dominant frequencies at the locations of impeller inlet, impeller outlet, and impeller blade surface are all 198 Hz (4 times of the rotation frequency 49.5 Hz), which indicates that the dominant frequency is in good agreement with the blade passing frequency (BPF). The first BPF dominates the frequency spectrum for all monitoring locations inside the pump.

Sign in / Sign up

Export Citation Format

Share Document