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%.

Natural Frequency Shift in a Centrifugal Compressor Impeller for High-Density Gas Applications

2011 ◽  
Author(s):  
Yohei Magara ◽  
Kazuyuki Yamaguchi ◽  
Haruo Miura ◽  
Naohiko Takahashi ◽  
Mitsuhiro Narita
Keyword(s):  
Centrifugal Compressor ◽  
Natural Frequencies ◽  
Mass Density ◽  
Mass Effect ◽  
Added Mass ◽  
High Density ◽  
Experimental Results ◽  
Centrifugal Compressors ◽  
Resonance Frequencies ◽  
Discharge Gas

In designing an impeller for centrifugal compressors, it is important to predict the natural frequencies accurately in order to avoid resonance caused by pressure fluctuations due to rotorstator interaction. However, the natural frequencies of an impeller change under high-density fluid conditions. The natural frequencies of pump impellers are lower in water than in air because of the added mass effect of water, and in high-pressure compressors the mass density of the discharge gas can be about one-third that of water. So to predict the natural frequencies of centrifugal compressor impellers, the influence of the gas must be considered. We previously found in the non-rotating case that some natural frequencies of an impeller decreased under high-density gas conditions but others increased and that the increase of natural frequencies is caused by fluid-structure interaction, not only the added mass effect but also effect of the stiffness of the gas. In order to develop a method for predicting natural frequencies of centrifugal compressor impellers for high-density gas applications, this paper presents experimental results obtained using a variable-speed centrifugal compressor with vaned diffusers. The maximum mass density of its discharge gas is approximately 300 kg/m3. The vibration stress on an impeller when the compressor was speeding up or slowing down was measured by strain gages, and the natural frequencies were determined by resonance frequencies. The results indicate that for high-density centrifugal compressors, some natural frequencies of an impeller increased in high-density gas. To predict this behavior, we developed a calculation method based on the theoretical analysis of a rotating disc. Its predictions are in good agreement with experimental results.

Natural Frequency Shift in a Centrifugal Compressor Impeller for High-Density Gas Applications

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Yohei Magara ◽  
Kazuyuki Yamaguchi ◽  
Haruo Miura ◽  
Naohiko Takahashi ◽  
Mitsuhiro Narita
Keyword(s):  
Centrifugal Compressor ◽  
Natural Frequencies ◽  
Mass Density ◽  
Mass Effect ◽  
Added Mass ◽  
High Density ◽  
Experimental Results ◽  
Centrifugal Compressors ◽  
Resonance Frequencies ◽  
Discharge Gas

In designing an impeller for centrifugal compressors, it is important to predict the natural frequencies accurately in order to avoid resonance caused by pressure fluctuations due to rotor-stator interaction. However, the natural frequencies of an impeller change under high-density fluid conditions. The natural frequencies of pump impellers are lower in water than in air because of the added mass effect of water, and in high-pressure compressors the mass density of the discharge gas can be about one-third that of water. So to predict the natural frequencies of centrifugal compressor impellers, the influence of the gas must be considered. We previously found in the nonrotating case that some natural frequencies of an impeller decreased under high-density gas conditions but others increased and that the increase of natural frequencies is caused by fluid-structure interaction, not only the added mass effect but also effect of the stiffness of the gas. In order to develop a method for predicting natural frequencies of centrifugal compressor impellers for high-density gas applications, this paper presents experimental results obtained using a variable-speed centrifugal compressor with vaned diffusers. The maximum mass density of its discharge gas is approximately 300 kg/m3. The vibration stress on an impeller when the compressor was speeding up or slowing down was measured by strain gauges, and the natural frequencies were determined by resonance frequencies. The results indicate that for high-density centrifugal compressors, some natural frequencies of an impeller increased in high-density gas. To predict this behavior, we developed a calculation method based on the theoretical analysis of a rotating disk. Its predictions are in good agreement with experimental results.

scholarly journals Some Numerical Approaches to Solve Fluid Structure Interaction Problems in Blood Flow

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Aik Ying Tang ◽  
Norsarahaida Amin
Keyword(s):  
Blood Flow ◽  
Fluid Structure Interaction ◽  
Computational Cost ◽  
Mass Effect ◽  
Rigid Wall ◽  
Added Mass ◽  
Multiscale Approach ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Numerical Approaches

Some numerical approaches to solve fluid structure interaction problems in blood flow are reviewed. Fluid structure interaction is the interaction between a deformable structure with either an internal or external flow. A discussion on why the compliant artery associated with fluid structure interaction should be taken into consideration in favor of the rigid wall model being included. However, only the Newtonian model of blood is assumed, while various structure models which include, amongst others, generalized string models and linearly viscoelastic Koiter shell model that give a more realistic representation of the vessel walls compared to the rigid structure are presented. Since there exists a strong added mass effect due to the comparable densities of blood and the vessel wall, the numerical approaches to overcome the added mass effect are discussed according to the partitioned and monolithic classifications, where the deficiencies of each approach are highlighted. Improved numerical methods which are more stable and offer less computational cost such as the semi-implicit, kinematic splitting, and the geometrical multiscale approach are summarized, and, finally, an appropriate structure and numerical scheme to tackle fluid structure interaction problems are proposed.

scholarly journals A SEMI-IMPLICIT APPROACH FOR FLUID-STRUCTURE INTERACTION BASED ON AN ALGEBRAIC FRACTIONAL STEP METHOD

2007 ◽  
Vol 17 (06) ◽  
pp. 957-983 ◽  
Author(s):  
A. QUAINI ◽  
A. QUARTERONI
Keyword(s):  
Fluid Structure Interaction ◽  
Mass Effect ◽  
Added Mass ◽  
Fractional Step ◽  
Step Method ◽  
Fractional Step Method ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Wide Range ◽  
Structure Problem

We address the numerical simulation of fluid-structure interaction problems characterized by a strong added-mass effect. We propose a semi-implicit coupling scheme based on an algebraic fractional-step method. The basic idea of a semi-implicit scheme consists in coupling implicitly the added-mass effect, while the other terms (dissipation, convection and geometrical nonlinearities) are treated explicitly. Thanks to this kind of explicit–implicit splitting, computational costs can be reduced (in comparison to fully implicit coupling algorithms) and the scheme remains stable for a wide range of discretization parameters. In this paper we derive this kind of splitting from the algebraic formulation of the coupled fluid-structure problem (after finite-element space discretization). From our knowledge, it is the first time that algebraic fractional step methods, used thus far only for fluid problems in computational domains with rigid boundaries, are applied to fluid-structure problems. In particular, for the specific semi-implicit method presented in this work, we adapt the Yosida scheme to the case of a coupled fluid-structure problem. This scheme relies on an approximate LU block factorization of the matrix obtained after the discretization in time and space of the fluid-structure system. We analyze the numerical performances of this scheme on 2D fluid-structure simulations performed with a simple 1D structure model.

scholarly journals A semi-implicit coupling technique for fluid–structure interaction problems with strong added-mass effect

2018 ◽  
Vol 80 ◽  
pp. 94-112 ◽  
Author(s):  
Alireza Naseri ◽  
Oriol Lehmkuhl ◽  
Ignacio Gonzalez ◽  
Eduard Bartrons ◽  
Carlos David Pérez-Segarra ◽  
...  
Keyword(s):  
Fluid Structure Interaction ◽  
Mass Effect ◽  
Added Mass ◽  
Fluid Structure ◽  
Coupling Technique ◽  
Structure Interaction

scholarly journals Fluid-structure interaction problems with strong added-mass effect

2009 ◽  
Vol 80 (10) ◽  
pp. 1261-1294 ◽  
Author(s):  
S. R. Idelsohn ◽  
F. Del Pin ◽  
R. Rossi ◽  
E. Oñate
Keyword(s):  
Fluid Structure Interaction ◽  
Mass Effect ◽  
Added Mass ◽  
Fluid Structure ◽  
Structure Interaction

scholarly journals Fluid-Structure Interaction Effects on the Propulsion of an Flexible Composite Monofin

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Adil El Baroudi ◽  
Fulgence Razafimahery
Keyword(s):  
Finite Element Method ◽  
Natural Frequencies ◽  
Fluid Structure Interaction ◽  
Water Environment ◽  
Interaction Model ◽  
Added Mass ◽  
Propulsive Efficiency ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Surrounding Fluid

Finite element method has been used to analyze the propulsive efficiency of a swimming fin. Fluid-structure interaction model can be used to study the effects of added mass on the natural frequencies of a multilayer anisotropic fin oscillating in a compressible fluid. Water by neglecting viscidity effects has been considered as a surrounding fluid and the frequency response of the fin has been compared with that of vacuum conditions. It has been shown that because of the added mass effects in water environment, the natural frequencies of the fin decrease.

Importance of Enclosed Gas for Modal Analysis of Space Inflatable Structure

2014 ◽  
Vol 1016 ◽  
pp. 244-248
Author(s):  
Fei Liu ◽  
Wei Liang He
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Fluid Structure Interaction ◽  
Mode Shapes ◽  
Follower Load ◽  
Nonlinear Finite Element Method ◽  
Load Effect ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Structure Research

The stress distribution and modal characteristics of a space inflatable torus is investigated using the nonlinear finite element method. This paper focused on the effect of enclosed air on the modal analysis of the torus, including the effect of follower pressure load and the effect of the interaction between the enclosed air and the torus structure. Research shows that follower pressure stiffness significantly reduces the natural frequencies and changes mode shapes order. The fluid-structure interaction obviously reduces the natural frequencies, and the in-plane translation mode is observed. Follower pressure stiffness has no effect on the in-plane translation mode. Fluid-structure interaction decreases the natural frequencies of the modal considering the follower load effect, but it does not change mode shapes order. The effect of enclosed gas seriously reduces the natural frequencies, changes mode shapes order, and produces the in-plane translation mode.

Coupling Model Analysis on Fluid Structure Interaction in Lifting Pipeling Based on ADINA

2012 ◽  
Vol 468-471 ◽  
pp. 238-244
Author(s):  
Zhao Wang ◽  
Zhi Jin Zhou ◽  
Hao Lu ◽  
Ze Jun Wen ◽  
Yi Min Xia
Keyword(s):  
Finite Element ◽  
Natural Frequency ◽  
Volume Concentration ◽  
Natural Frequencies ◽  
Fluid Structure Interaction ◽  
Element Model ◽  
Structure Design ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Finite Element Software

Using finite element software ADINA, three coupling models on fluid-structure interaction among internal fluid—pipe—external fluid in the lifting pipeline were researched. Firstly, coupling finite element model on fluid structure interaction of lifting pipeline was established and the first sixth order natural frequencies and principal vibration modes were attained at different ore conveying volume concentration and cross-section size of pipeline;Then natural frequencies of three couplings were compared with two couplings and no coupling according to the above condition, and FSI effect on natural frequency of pipeline was discussed. The calculation results were shown that the natural frequency of the pipe and its relative error reduced with the volume concentration and the relative wall thickness increased, which explain the reason that has better accuracy considering three couplings than other .These results have certain directive significance on the dynamic response, structure design and study of reduction vibration of lifting pipeline.

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