Fluid-Structure Interaction Effects of a Partially Immersed, Cantilevered Hydrofoil

2021 ◽  
Author(s):  
Yongshun Zeng ◽  
Xin Qi ◽  
Lingfeng Shu ◽  
Zhifeng Yao ◽  
Lingjiu Zhou ◽  
...  
Keyword(s):  
Free Surface ◽  
Mode Shape ◽  
Guide Vane ◽  
Damping Ratio ◽  
Fluid Structure Interaction ◽  
Side Wall ◽  
Added Mass ◽  
Modal Parameters ◽  
Structure Interaction ◽  
Operating Stability

Abstract Knowledge of the modal parameters of the guide vane is essential for evaluating the operating stability of pump-turbines. In the present investigation, experiments and simulations are designed to analyze the influence of submergence level and sidewall clearance on the vibration characteristics of a guide vane-like structure. The results show that the type of mode shape remains unchanged at different submergence levels, while the position of the node line (NL) demonstrates a slight shift. According to the angle of the NL and the free surface, the mode types are divided into parallel NL, vertical NL and slanted NL modes. The added mass tends to increase with increasing submergence levels, while the slope of added mass in conjunction with the submergence level, is dependent on the mode type. In particular, in relation to the parallel NL mode, the slope is almost zero, if the free surface is close to the NL region; with regard to the slanted NL mode, the slope in the NL region is significant smaller than that outside this region; in the case of the vertical NL mode, the slope remains approximately constant. The damping ratio increases with increasing submergence level for the vertical NL mode. While the damping ratios for the parallel and slanted NL modes are decreased, if the free surface is close to the NL regions. In addition, as the side wall clearance increases, both the added mass and damping ratio tend to decrease.

Fluid Structure Interaction Simulations Involving Free Surface

2018 ◽  
Author(s):  
H. R. Díaz-Ojeda ◽  
L. M. González ◽  
F. J. Huera-Huarte
Keyword(s):  
Free Surface ◽  
Circular Cylinder ◽  
Fluid Structure Interaction ◽  
Flexible Structure ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Classical Fluid ◽  
Simple Geometry ◽  
Different Depths

The aim of this paper is to evaluate how much affects the presence of gravity and free-surface to a flexible structure in a classical fluid structure interaction (FSI) problem typically found in off-shore problems and other oceanic applications. The base problem selected is the Turek benchmark case where a deformable plate is attached to the wake of a circular cylinder. To focus on the differences of considering free surface, a simple geometry has been selected and two different situations have been studied: the first one is the classical Turek benchmark, the second is a similar geometry but adding gravity and free surface. The free surface problem was studied placing the structure at different depths and monitoring the deformation and forces on the structure.

Natural Frequencies of Centrifugal Compressor Impellers for High Density Gas Applications

2008 ◽  
Author(s):  
Yohei Magara ◽  
Mitsuhiro Narita ◽  
Kazuyuki Yamaguchi ◽  
Naohiko Takahashi ◽  
Tetsuya Kuwano
Keyword(s):  
Centrifugal Compressor ◽  
Natural Frequencies ◽  
Fluid Structure Interaction ◽  
Mass Effect ◽  
Added Mass ◽  
High Density ◽  
Experimental Results ◽  
Density Condition ◽  
Fluid Structure ◽  
Structure Interaction

Characteristics of natural frequencies of an impeller and an equivalent disc were investigated in high-density gas to develop a method for predicting natural frequencies of centrifugal compressor impellers for high-density gas applications. The equivalent disc had outer and inner diameters equal to those of the impeller. We expected that natural frequencies would decrease with increasing the gas density because of the added-mass effect. However, we found experimentally that some natural frequencies of the impeller and the disc in high-density gas decreased but others increased. Moreover, we observed, under high-density condition, some resonance frequencies that we did not observe under low-density condition. These experimental results cannot be explained by only the added-mass effect. For simplicity, we focused on the disc to understand the mechanism of the behavior of natural frequencies. We developed a theoretical analysis of fluid-structure interaction considering not only the mass but also stiffness of gas. The analysis gave a qualitative explanation of the experimental results. In addition, we carried out a fluid-structure interaction analysis using the finite element method. The behavior of natural frequencies of the disc in high-density gas was predicted with errors less than 6%.

Fluid-Structure Interaction Simulation With Free Surface Flows by Smoothed Particle Hydrodynamics

2008 ◽  
Author(s):  
M. H. Farahani ◽  
N. Amanifard ◽  
H. Asadi ◽  
M. Mahnama
Keyword(s):  
Free Surface ◽  
Fluid Structure Interaction ◽  
Free Surface Flows ◽  
Surface Flows ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Incompressibility Constraint ◽  
Sph Algorithm

Simulation of the fluid-structure interaction (FSI) and free surface flows includes an area of extremely challenging problems in the computational mechanics community. In this paper, a newly proposed SPH algorithm is employed to simulate FSI problems with complex free surface flows. In this way, fluid and elastic structure continua are coupled using a monolithic but explicit numerical scheme. The proposed method is similar to so-called SPH projection method and consists of three steps. The first two steps play the role of prediction, while in the third step a Poisson equation is used for both fluid and structure to impose incompressibility constraint.

The Comparative Modal Analysis of Simulation and Experiment on the Electronic Button-Sewing Machine Shell

2013 ◽  
Vol 668 ◽  
pp. 612-615
Author(s):  
Li Zhang ◽  
Guang Yuan Nie ◽  
Hong Wu ◽  
Jie Chen
Keyword(s):  
Comparative Analysis ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Mode Shape ◽  
Damping Ratio ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Ansys Software ◽  
Sewing Machine ◽  
Simulation And Experiment

In this paper, the simulation with ANSYS software and the experimental modal analysis by impacting are carried out on the electronic button-sewing machine shell. The modal parameters, such as the natural frequency, the damping ratio and the mode shape, are obtained. Comparative analysis of their results shows that the mode shapes of the machine shell are mainly the outward-expanding and inward-contracting vibrations, which provides a useful reference for vibration and noise reduction of the electronic button-sewing machine.

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