MODAL PARAMETER EXTRACTION OF A HUGE FOUR STAGE CENTRIFUGAL COMPRESSORS USING OPERATIONAL MODAL ANALYSIS METHOD

  • SATTAR MOHAMMADI ESFARJANI Fixed equipment inspector/ instructor
  • MEHDI SALEHI Assistant Professor Faculty of Engineering Najafabad branch Islamic Azad University
  • MEHDI GHORBANI M.Sc Mechanical engineering, Department of mechanical engineering, Khominishahr Branch, Islamic Azad University, Khominishahr, Iran
Keywords: OPERATIONAL MODAL ANALYSIS, HARMONIC COMPONENT, MODAL PARAMETERS, CENTRIFUGAL COMPRESSOR DISTRIBUTION.

Abstract

IN RECENT YEARS, MODAL ANALYSIS HAS BECOME ONE OF THE ESSENTIAL METHODS FOR MODIFICATION AND OPTIMIZATION OF DYNAMIC CHARACTERISTICS OF ENGINEERING STRUCTURES. THIS IS THE FIRST STUDY TO IDENTIFY MODAL PARAMETERS OF A COMPLEX FOUR-STAGE CENTRIFUGAL COMPRESSOR USING OPERATIONAL MODAL ANALYSIS (OMA). VIBRATIONAL RESPONSE WAS MEASURED CONTINUOUSLY WITH SAMPLING FREQUENCY OF 44100(HZ) BY FOUR NONCONTACT EDDY CURRENT SENSORS. APPLIED FORCES IN ACTUAL WORKING CONDITION DURING COMPRESSOR’S OPERATION WERE CONSIDERED AS EXCITATION FORCES. IN THIS STUDY, MODAL PARAMETERS WERE EXTRACTED AND COMPARED USING SOME VARIOUS OMA METHODS, INCLUDES; FREQUENCY DOMAIN DECOMPOSITION (FDD), ENHANCED FREQUENCY DOMAIN DECOMPOSITION (EFDD) AND STOCHASTIC SUBSPACE IDENTIFICATION (SSI), WITH PULSETM TYPE 3560-D SYSTEM AND DEVELOPED IN MATLAB SOFTWARE. THE RESULTS SHOW THAT SSI METHOD HAS A HIGHER ACCURACY COMPARED TO FDD AND EFDD METHODS. HOWEVER, FDD SHOWS BETTER RESULTS WHEN SYSTEM DAMPING IS LOW IN ONE OF THE MODES.
Published
2018-02-05
Section
Articles