Investigating the influence of compressibility on the second mode flutter instability of a clamped–free cylinder in axial flow using fluid–structure interaction simulations with the Chimera technique

2022 ◽  
Vol 109 ◽  
pp. 103469
Author(s):  
Lucas Delcour ◽  
Axel Bral ◽  
Lieva Van Langenhove ◽  
Joris Degroote
Keyword(s):  
Fluid Structure Interaction ◽  
Axial Flow ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Flutter Instability ◽  
Second Mode

scholarly journals Study into the Improvement of Dynamic Stress Characteristics and Prototype Test of an Impeller Blade of an Axial-Flow Pump Based on Bidirectional Fluid–Structure Interaction

2019 ◽  
Vol 9 (17) ◽  
pp. 3601 ◽  
Author(s):  
Kan Kan ◽  
Yuan Zheng ◽  
Huixiang Chen ◽  
Jianping Cheng ◽  
Jinjin Gao ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Stress ◽  
Fluid Structure Interaction ◽  
Axial Flow ◽  
Gravity Effect ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Prototype Test ◽  
Axial Flow Pump ◽  
Flow Pump

This paper performed a numerical study into the dynamic stress improvement of an axial-flow pump and validated the simulation results with a prototype test. To further analyze the dynamic stress characteristics of impeller blades of axial-flow pumps, a bidirectional fluid–structure interaction (FSI) was applied to numerical simulations of the unsteady three-dimensional (3-D) flow field of the whole flow system of an axial-flow pump, and the gravity effect was also taken into account. In addition, real-structure-based single-blade finite element model was established. By using the finite element method, a calculation of the blade’s dynamic characteristics was conducted, and its dynamic stress distribution was determined based on the fourth strength theory. The numerical results were consistent with the prototype tests. In a rotation cycle, the dynamic stress of the blade showed a tendency of first increasing, and then decreasing, where the maximum value appeared in the third quadrant and the minimum appeared in the first quadrant in view of the gravity effect. A method for reducing the stress concentration near the root of impeller blades was presented, which would effectively alleviate the possibility of cracking in the unreliable region of blades. Simultaneously, an experimental method for the underwater measurement of the dynamic stress of prototypical hydraulic machinery was put forward, which could realize the underwater sealing of data acquisition instruments on rotating machinery and the offline collection of measured data, finally effectively measuring the stress of underwater moving objects.

A Coupled Two-Way Fluid-Structure Interaction Analysis for the Dynamics of a Partially Confined Cantilevered Pipe Under Simultaneous Internal and External Axial Flow in Opposite Directions

2021 ◽  
Author(s):  
Farhang Daneshmand ◽  
Tahereh Liaghat ◽  
Michael Paidoussis
Keyword(s):  
Interaction Analysis ◽  
Velocity Ratio ◽  
Fluid Structure Interaction ◽  
Axial Flow ◽  
Internal Flow ◽  
Structural Domain ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Cantilevered Pipe ◽  
Central Pipe

Abstract This paper presents the results of a coupled two-way fluid-structure interaction analysis of a slender flexible vertical cantilevered pipe hanging concentrically within a shorter rigid tube forming an annulus. The pipe is subjected to internal and annular flows simultaneously. This system has applications in brine production and salt-cavern hydrocarbon storage. In the present study, the fluid-structure problem is solved with a finite-volume-based CFD code for the fluid domain coupled to a finite-element-based CSM code for the structural domain. The numerical results obtained for the free-end displacement of the central pipe versus the annular/internal flow velocity ratio U_o/U_i are presented and compared with those obtained from experiment. The capability of the numerical model to predict the onset of the experimentally observed flutter instability in the system is also examined. This provides a better insight into the dynamics of the system.

A Boundary Element Method for Dynamic Analysis of Elastic Structures Subjected to Axial Flow

2006 ◽  
Author(s):  
Bahadir Ugˇurlu ◽  
Ahmet Ergin
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Potential Function ◽  
Fluid Structure Interaction ◽  
Axial Flow ◽  
Elastic Structure ◽  
Elastic Structures ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Element Method

A boundary element method is presented to investigate the dynamic behavior of elastic structures partially or completely in contact with uniform axial flow. In the analysis of the linear fluid-structure interaction problem, it is assumed that the fluid is ideal and its motion is irrotational. Furthermore, the elastic structure is assumed to vibrate in relatively high-frequencies, so the infinite frequency limit condition is imposed for fluid free surface, which is satisfied implicitly by using method of images. When in contact with the flowing fluid, the structure is assumed to vibrate in its in vacuo eigen-modes that are obtained by using a finite element software. The wetted surface of the structure is idealized by using appropriate hydrodynamic panels and a boundary element method is formulated for velocity potential function, which is taken as linearly varying over the panels. Using the Bernoulli’s equation, the dynamic fluid pressure on the elastic structure is expressed in terms of potential function, and the fluid-structure interaction forces are calculated as generalized added mass, hydrodynamic damping and hydrodynamic stiffness coefficients, due to the inertia, Coriolis and centrifugal effects of fluid, respectively. Solution of the eigenvalue problem associated with the generalized equation of motion gives the dynamic characteristics of the structure in contact with fluid. As an application of the method, the dynamics of a simply supported cylindrical shell subjected to internal flow is studied. The predictions compare quite well with the previous results in the literature.

scholarly journals Comparative Analysis of Strength and Modal Characteristics of a Full Tubular Pump and an Axial flow Pump Impellers Based on Fluid-Structure Interaction

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6395
Author(s):  
Lijian Shi ◽  
Jun Zhu ◽  
Li Wang ◽  
Shiji Chu ◽  
Fangping Tang ◽  
...  
Keyword(s):  
Equivalent Stress ◽  
Fluid Structure Interaction ◽  
Axial Flow ◽  
Total Deformation ◽  
Stress Concentrations ◽  
Pump Impeller ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Axial Flow Pump ◽  
Flow Pump

Fluid-structure interaction (FSI) was used to determine the structural mechanical characteristics of full tubular and axial-flow pumps. The results showed that as the flow rate increases, the total deformation and equivalent stress are significantly reduced. The max total deformation (MTD) and the max equivalent stress (MES) of the full tubular pump impeller occur on the outer edge of the blade. There are two stress concentrations in the full tubular pump impeller, one of which is located in the outlet area of the rim, and the other is located in the outlet area of the hub. However, the MES of the axial-flow pump appears in the center of the blade hub. The performance difference between the full tubular pump and the axial-flow pump is mainly caused by the clearance backflow. The natural frequency of the full tubular pump is lower than that of the axial-flow pump on the basis of the modal results. The MES of the full tubular pump is mainly concentrated at the junction of the blade and the motor rotor, and the max thickness of the rim is 6mm, which can be more prone to cracks and seriously affect the safety and stability of the pump.

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