Kanatlı Rotorun Deneysel ve Sayısal Modal Analizi

Öz

The behavior of an asymmetric bladed rotor was investigated in this study. The bladed rotor which performs solid-solid, liquid-liquid, liquid-solid separation processes is part of the decanter machine and named as screw conveyor. The purpose of this study is to determine the dynamics of the rotor on the free conditions for future development of the asymmetric and blade assembled rotors. It is important for the designer to determine the natural frequencies of the bladed asymmetric rotor so that some precautions can be taken during the design of the machine and in the operating conditions of the machine. This study consisted of two parts. In the experimental one, the modal test of the bladed rotor was performed and in the numerical part, the modal analysis of the rotor was carried out under free-free boundary conditions using a simulation program based on the finite-element method. The natural frequencies of the blades and the rotor were obtained experimentally and numerically. It was found that the experimental results and numerical results were in good agreement. Besides, it was concluded that the two mode shape was equal to the transverse mode frequency of the rotor and blades and the following mode shapes correspond to the bending and torsion mode frequencies of the blades. Since the shape properties of the rotor and blades are different, it has been observed experimentally and numerically that their natural frequencies also differ.

Anahtar Kelimeler

• Bladed Rotor
• Experimental Modal Analysis (EMA)
• Finite Element Analysis (FEM)
• Natural Frequency Analysis

Experimental and Numerical Modal Analysis of a Bladed Rotor

Abstract

The behavior of an asymmetric bladed rotor was investigated in this study. The bladed rotor which performs solid-solid, liquid-liquid, liquid-solid separation processes is part of the decanter machine and named as screw conveyor. The purpose of this study is to determine the dynamics of the rotor on the free conditions for future development of the asymmetric and blade assembled rotors. It is important for the designer to determine the natural frequencies of the bladed asymmetric rotor so that some precautions can be taken during the design of the machine and in the operating conditions of the machine. This study consisted of two parts. In the experimental one, the modal test of the bladed rotor was performed and in the numerical part, the modal analysis of the rotor was carried out under free-free boundary conditions using a simulation program based on the finite-element method. The natural frequencies of the blades and the rotor were obtained experimentally and numerically. It was found that the experimental results and numerical results were in good agreement. Besides, it was concluded that the two mode shape was equal to the transverse mode frequency of the rotor and blades and the following mode shapes correspond to the bending and torsion mode frequencies of the blades. Since the shape properties of the rotor and blades are different, it has been observed experimentally and numerically that their natural frequencies also differ. 

Keywords

• Bladed Rotor
• Experimental Modal Analysis (EMA)
• Finite Element Analysis (FEM)
• Natural Frequency Analysis

Kaynakça

1. [1] D.J. Ewins, “The Effects of Detuning upon the Forced Vibrations of Bladed Disk”, Journal of Sound and Vibrations 9 (1), 65-79, 1969.
2. [2] A. V. Srinivasan, “Flutter and Resonant Vibration Characteristics of Engine Blades”, Journal of Engineering for Gas Turbines and Power, 119, 742-775, 1997.
3. [3] R. Rzadkowski, A. Maurin, M. Drewczynski, “Multistage Coupling of Mistuned Aircraft Engine Bladed Disks in a Free Vibration Analysis”, 11th International Conference on Vibration Problems, Lisbon, Portugal, 9-12 September 2013.
4. [4] Y. Kaneko, R. Nakanishi, K. Mori, H. Ohyama, “Study on Vibration Characteristics of Mistuned Bladed Disk (Vibration Response Analysis by Reduced Model FMM)”, Journal of System Design and Dynamics, 7(4), 2013.
5. [5] R. Fernandes, S. El-Borgi, K. Ahmed, M. I. Friswell and N. Jamia, “Static Fracture and Modal Analysis Simulation of a Gas Turbine Compressor Blade and Bladed Disk System”, Advanced Modeling and Simulation in Engineering Sciences, 3(30), 2016.
6. [6] O. Repetckii, I. Ryzhikov, T. Q. Nguyen, “Investigation of Mistuning Impact on Vibration of Rotor Bladed Disks”, IOP Conf. Series: Journal of Physics: Conf. Series, 012097, 944, 2018.
7. [7] Z. Jin, G. Tian-yu, C. Yi, X. Hong-hao, “Model Updating of Dual-Rotor Decanter Centrifuge with Dynamic Test”, Journal of ZheJiang University (Engineering Science) 53.2, 241-249, 2004.
8. [8] J. Yang, S. Preidikman, E. A. Balaras, “Strongly Coupled, Embedded-Boundary a Method for Fluid Structure Interactions of Elastically Mounted Rigid Bodies”, Journal of Fluid Structure, 24(2):167-182, 2008.

9. [9] L.Q. Wang, T. Chen, D.Z. Wu, “Structural Strength Parameterized Analysis of Horizontal Decanter Centrifuge Conveyor”, Journal of Mechanical Design, 27(5):67-70, 2010.
10. [10] B. Donohue, “The Transient Behavior of the Co-Axial Non-Synchronous Rotating Assembly of a Decanting Centrifuge”, University of Canterbury, Department of Mechanical Engineering, New Zeland, 169 pages, Doctoral Thesis, 2014.
11. [11] C. Hua, Z. Rao, T. Na, “Nonlinear Dynamics of Rub-Impact on a Rotor-Rubber Bearing System with the Stribeck Friction Model”, Journal of Mechanical Science and Technology, 29 (8):3109–3119, 2015.
12. [12] H. Liu, P. Li, H. Xiao, W. Mu, “The Fluid Solid Coupling Analysis of Screw Conveyor in Drilling Fluid Centrifuge Based on Ansys”. Petroleum, 1(3):251-256, 2015.
13. [13] W. Tan, L. Huai-min, H. Wu, Z. Li, H. Lou, “Numerical Study on the Coupled Vibration Characteristics of the Dual-Rotors System with Little Rotation Speed Difference”, Journal of Vibroengineering 17(4), 1719-1730, 2015.
14. [14] G. Jiayi, G. Luo, “Modal Test and Finite Element Analysis of a Turbine Disk,” Vibroengineering PROCEDIA 20, 108-112, 2018.
15. [15] B. Peetersa, H.V. Auweraera, P. Guillaumeb and J. Leuridana, The Polymax FrequencyDomain Method: A New Standard for Modal Parameter Estimation?, Shock and Vibration 11, 395–409, 2004.
16. [16] M. Yaman, Hafif ticari bir araç jantının, sonlu elemanlar modelinin oluşturulması ve doğrulanması. Y. Lisans, İTÜ, Fen Bilimleri Enstitüsü, Makine Mühendisliği Anabilim Dalı, İstanbul, 2012.
17. [17] Y.N. Aydın, Lastikli Jant İçin Sönümleyici Kompozit Tasarımı, Deneysel ve Nümerik Analizi, Y. Lisans, MCBÜ, Fen Bilimleri Enstitüsü, Makine Mühendisliği Anabilim Dalı, Manisa, 2021.