Compressor Upgrade on Existing Platform: A Study on Vibration from Structural Perspective

2021 ◽  
Author(s):  
See Yee Teh ◽  
Ahmad Rizal A Rahman ◽  
Raja Sharifuddin Ahmad Raja Badrol ◽  
Mohd Hafis Muhammad Daud
Keyword(s):  
Dynamic Analysis ◽  
Structural Engineering ◽  
Dynamic Effect ◽  
Forced Response ◽  
Project Team ◽  
Response Analysis ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Processing Platform ◽  
Gas Lift

Abstract Due to an increase in gas lift demand on an existing field in Sarawak, an existing Gas Lift Compressor (GLC) on the processing platform requires to be upgraded to meet incremental oil production requirement. These sets of compressors consist of 2x100% reciprocating compressors that were designed for 1.5 MMscfd each, with discharge pressure of 55.1 barg (800psig). The gas from these compressors is used mainly for gas lift at the processing platform as well as gas lift, instrument gas and utility gas at adjacent wellhead platforms. From the Conceptual Study, the existing compressors are not able to be retrofit for upgrade and is to be replaced with 2 × 100 % new gas engine driven compressor that capable of delivery 3.0 MMscfd of compressed gas each. During the engineering stage of GLC package, Skid Dynamic Analysis has been carried out to evaluate the GLC skid structural design due to the operating dynamic load cases. The study recommended that the skid to be welded to the platform where the compressor is located to prevent the risk of high vibration. With the recommendation from Contractor's study, project team proceeded to carry out Structural Dynamic Analysis to assess the dynamic effect of the GLC skids to the platform deck. The Finite Element Analysis (FEA) results revealed that there are several modal modes mainly at the drilling deck and extension deck non-compliance to PTS guideline. Structural Dynamic Modification (SDM) and optimization was performed to dynamically stiffens the structures to shift the modal modes away from the operating range to fulfil PTS criteria. However, the SDM results was still unable to comply thus the need of Anti-Vibration Mounts (AVMs) is considered. Prior to application of AVMs, Structural Forced Response Analysis needs to be carried out to evaluate the risk of the system and confirm the requirement of the AVMs. Without the forced response analysis, the effect of AVMs, locations and numbers of AVMs cannot be addressed during the design study. This paper will discuss the issues concerning vibration from reciprocating compressors upgrade on an existing platform, changes in the existing operating and design philosophy, challenges in addressing compressor installation and utilization of AVM from the perspective of Project Team. The paper will also provide key lessons learn and recommendation for future considerations in Compressor upgrades on existing facilities from a Structural Engineering point of view. The project is currently at its detail design finalization and installation is expected to be completed by November 2021.

Regeneration-Induced Forced Response in Axial Turbines

2013 ◽  
Author(s):  
Jens Aschenbruck ◽  
Christopher E. Meinzer ◽  
Linus Pohle ◽  
Lars Panning-von Scheidt ◽  
Joerg R. Seume
Keyword(s):  
Turbine Blades ◽  
Forced Response ◽  
Response Analysis ◽  
Geometrical Parameters ◽  
Turbine Stage ◽  
Structural Dynamic ◽  
Air Turbine ◽  
Axial Turbines ◽  
Interaction Approach ◽  
Stagger Angle

The regeneration of highly loaded turbine blades causes small variations of their geometrical parameters. To determine the influence of such regeneration-induced variances of turbine blades on the nozzle excitation, an existing air turbine is extended by a newly designed stage. The aerodynamic and the structural dynamic behavior of the new turbine stage are analyzed. The calculated eigenfrequencies are verified by an experimental modal analysis and are found to be in good agreement. Typical geometric variances of overhauled turbine blades are then applied to stator vanes of the newly designed turbine stage. A forced response analysis of these vanes is conducted using a uni-directional fluid-structure interaction approach. The effects of geometric variances on the forced response of the rotor blade are evaluated. It is shown that the vibration amplitudes of the response are significantly higher for some modes due to the additional wake excitation that is introduced by the geometrical variances e.g. 56 times higher for typical MRO-induced variations in stagger-angle.

Experiences From Structural Dynamic Analysis Projects of BWR Plants Within the Scope of Power Uprate Projects Using FEA

2010 ◽  
Author(s):  
Bjo¨rn Sva¨rd ◽  
Jan-Anders Larsson ◽  
Philip Ma˚rtensson ◽  
Bjo¨rn Lundin
Keyword(s):  
Finite Element Analysis ◽  
Dynamic Analysis ◽  
Structural Models ◽  
Dynamic Interactions ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Global Models ◽  
Dynamic Verification ◽  
Strong Dynamic ◽  
Reactor Pressure

During recent years, power-uprate projects have been executed at several BWR-units in Sweden. As part of these projects, structural verification of the safety-related buildings as well as the new and old internal parts of the reactor pressure vessel, RPV, has been performed. In this document, some experiences will be presented from structural dynamic verification, using finite element analysis, FEA, within the scope of these power uprate projects. From this work, a number of conclusions can be drawn. Global models with dense meshes can successfully be used for a broad range of applications. Today, large FEA-models can be used efficiently, e.g. in global vibration and structural verification analyses, if suitable dynamic analysis methods are used. There can be strong dynamic interactions between the containment, fluids, the RPV and RPV-internals. Stress calculation and evaluation can be executed efficiently on large models. The structural models can with advantage be re-utilized in future projects.

A Discrete Model to Consider the Influence of the Air Flow on Blade Vibrations of an Integral Blisk Compressor Rotor

2008 ◽  
Author(s):  
Bernd Beirow ◽  
Arnold Ku¨hhorn ◽  
Sven Schrape
Keyword(s):  
Air Flow ◽  
Forced Response ◽  
Response Analysis ◽  
Element Analysis ◽  
Compressor Rotor ◽  
Aerodynamic Properties ◽  
Cascade Arrangement ◽  
Simple Mass ◽  
Mass Spring ◽  
Elastically Supported

The influence of the aerodynamic coupling in the forced response analysis of a HPC test-blisk is studied by means of a reduced order mechanical model. In the first step this equivalent blisk model (EBM) is derived based on a finite element analysis of the disk from design and an adjustment to experimentally determined blade alone frequencies in order to consider the real blade mistuning. Applying the EBM — so far not considering the air flow influence — to carry out forced response analyses due to a rotating excitation acting on the stationary blisk, a maximum blade displacement amplification of more than 50% has been calculated comparing the tuned and the mistuned blisk. Aiming at an additional consideration of the air flow, fully coupled computations of the fluid structure interaction (FSI) are exemplarily carried out for elastically supported blades in a cascade arrangement. The results are used to calibrate simple mass-spring-damper models from which quantities of additional aerodynamic elements in terms of a consideration of co-vibrating air masses, air stiffening and aerodynamic damping are derived. Based on this information the EBM is extended to a so called advanced EBM. Aerodynamic influences are considered assigning the aerodynamic properties to each blade in dependence on the inter blade phase angle (IBPA). Forced response analyses, now including all aerodynamic influences, show that for an extreme application of a rear blisk close to the combustion chamber and under MTO conditions a strong smoothing of originally localized vibration modes occurs. The maximum blade displacement amplification due to mistuning is decreased from more than 50% to below 12% for the first blade flap mode.

Simplified Dynamic Finite-Element Analysis for Three-Dimensional Pile-Grouped-Raft-High-Rise Buildings

2008 ◽  
Vol 400-402 ◽  
pp. 613-619
Author(s):  
Hui Xiong ◽  
Shou Ping Shang ◽  
Liang Huang
Keyword(s):  
Finite Element ◽  
Structural Engineering ◽  
Computational Cost ◽  
Time History ◽  
Pile Group ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Shell Elements ◽  
High Rise ◽  
Mass Spring

Combined with the respective advantages in S-R(Sway-Rocking) impedance concept and finite-element method, a simplified 3D structural dynamic FEM considering composite pile-group-soil effects is presented. The structural members including piles are modeled by spacial beam or shell elements, and raft-base is divided into thick-shell elements with its spring-dashpot boundary coefficient obtained by impedance backcalculated. The mass-spring elements for soil between piles are set to simulate vertical, horizontal pile-group effects by strata-equivalent approach. The soil beside composite body is separated into near-field and far-field parts. The former is modeled by nonlinear spring-dashpot elements based on Winkler’s hypothesis, while the latter is modeled by a series of linear mass-spring-dashpots. With the effects of boundary track forces and energy radiation, the presented model enables researchers to conduct the time-domain nonlinear analysis in a relatively simple manner which avoids sophisticated boundary method and solid-element mesh bringing with tremendous computational cost. The seismic effect on dynamic interaction of pile-soil-complicated structures would be efficiently annotated from two structural engineering and geotechnical engineering aspects and the numerical calculation effort would be drastically decreased too. The complete procedure is mainly performed using the parametric design language assembled in the Finite Element Code Ansys. With the dynamic analysis of foundation and superstructure for a pile-supported 15-storey building, the influence of the participant effect on structural dynamic response will be depicted by various dynamic parameters of pile-soil-raft foundation in detail. Not only do the results have an agreement with some conclusions drawn by the general interaction theory, but also certain of phenomena which would be disagree with that by general analysis is involved. Even with the finite-element meshes for 68 piles, the time-history analysis procedure for PGSS (Pile-Group-Soil-Superstructure) system and the qualitative evaluation with various SSI parameters can be also fulfilled efficiently and rapidly by presented means. These results may be of help to the designers to quickly assess the significance of interaction effect for the high-rise buildings resting on any type or layout of pile-group foundation.

Inelastic Dynamic Analysis of Steel Structure Using Force Analogy Method

2012 ◽  
Vol 166-169 ◽  
pp. 304-309 ◽  
Author(s):  
Shi Qiang Song ◽  
Gang Li
Keyword(s):  
Dynamic Analysis ◽  
Plastic Hinge ◽  
Nonlinear Dynamic Analysis ◽  
Steel Structure ◽  
Response Analysis ◽  
Analysis Method ◽  
Element Analysis ◽  
Analogy Method ◽  
Traditional Algorithm ◽  
Response State

Force analogy method is a kind of nonlinear dynamic analysis method. Analyzing inelastic structural behavior by using plastic hinge theory, it is widely appropriate to many structures with different material properties and very time efficient and numerically accurate without complicated iterative computations in traditional algorithm. Compared with the traditional finite-element analysis method, dynamic response analysis based on force analogy method has obvious advantages. The application of force analogy method to a steel structure is presented and the analysis result shows that the method algorithm can represent each response state of the structure in real-time and has the very good accuracy and practical.

scholarly journals Implementation of Speed Variation in the Structural Dynamic Assessment of Turbomachinery Flow Path Components

2013 ◽  
Author(s):  
Andrew M. Brown ◽  
R. Benjamin Davis ◽  
Michael K. DeHaye
Keyword(s):  
Resonant Frequency ◽  
Dynamic Assessment ◽  
Excitation Frequency ◽  
Flow Path ◽  
Forced Response ◽  
Response Analysis ◽  
Structural Dynamic ◽  
Speed Variation ◽  
Time Histories ◽  
Life Analysis

During the design of turbomachinery flow path components, the assessment of possible structural resonant conditions is critical. Higher frequency modes of these structures are frequently found to be subject to resonance, and in these cases, design criteria require a forced response analysis of the structure with the assumption that the excitation speed exactly equals the resonant frequency. The design becomes problematic if the response analysis shows a violation of the HCF criteria. One possible solution is to perform “finite-life” analysis, where Miner’s rule is used to calculate the actual life in seconds in comparison to the required life. In this situation, it is beneficial to incorporate the fact that, for a variety of turbomachinery control reasons, the speed of the rotor does not actually dwell at a single value but instead dithers about a nominal mean speed and during the time that the excitation frequency is not equal to the resonant frequency, the damage accumulated by the structure is diminished significantly. Building on previous investigations into this process, we show that a steady-state assumption of the response is extremely accurate for this typical case, resulting in the ability to quickly account for speed variation in the finite-life analysis of a component which has previously had its peak dynamic stress at resonance calculated. A technique using Monte Carlo simulation is also presented which can be used when specific speed time histories are not available. The implementation of these techniques can prove critical for successful turbopump design, as the improvement in life when speed variation is considered is shown to be greater than a factor of two.

Improved Large Spring / Stiffness Technique for Dynamic Response Analysis of Structures Subjected to Base Excitations

2011 ◽  
Vol 474-476 ◽  
pp. 1974-1979
Author(s):  
Guo Liang Zhou ◽  
Xiao Jun Li ◽  
Xiao Bo Peng
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Response Analysis ◽  
Spring Stiffness ◽  
Seismic Excitations ◽  
Structural Dynamic ◽  
Theoretical Methods ◽  
Rayleigh Damping ◽  
Stiffness Method ◽  
Improved Technique

Based on the large spring/stiffness method (LSM), this paper develops an improved technique (I-LSM) applicable to structural dynamic analysis with the assumption of Rayleigh damping. To estimate the accuracy of the technique, the dynamic response is analyzed for a 2-DOFs model respectively subjected to uniform/nonuniform seismic excitations. It indicates that the traditional LSM is inapplicable when Rayleigh damping is adopted. And the errors increase monotonously with the aggrandizement of damping. It’s also validated that the I-LSM based on the modification of displacement considering the influences of Rayleigh damping presented in this paper is able to effectively yield results almost identical to those of theoretical methods with errors beneath 4%.

A Forced Response Method for Annular Combustors Excited by Traveling Acoustic Pressure Waves

2008 ◽  
Author(s):  
Sanghum Baik ◽  
Mehmet Dede
Keyword(s):  
Finite Element ◽  
Pressure Wave ◽  
Acoustic Pressure ◽  
Response Prediction ◽  
Element Model ◽  
Forced Response ◽  
Response Analysis ◽  
Element Analysis ◽  
Variable Theory ◽  
Response Method

Recent progress in the development of an industry level tool for computing forced response of annular combustors is presented. Hereby, in addressing productivity issues caused by huge finite element model of full-wheel combustor, the theoretical framework of cyclic symmetry is introduced. The complex-variable theory, which originated for capturing natural frequency and mode shape characteristics of rotationally periodic structure, was extended for real-number-based finite element analysis (FEA) to solve forced response problem; specifically, a systematic method was developed to create cyclic domain replica of traveling pressure wave loading on full-wheel combustor. In this paper, theoretical descriptions of the physics-based, practical forced response analysis technique will be provided, and its implementation into building the tool of industrial level will be discussed. The technology developed herein will be verified using a simple cylindrical structure that is excited by acoustic pressure wave that travels in circumferential direction with a certain number of nodal diameter. In the end, a practical application to forced response prediction of a combustor component will be presented.

scholarly journals AEROELASTIC ANALYSIS OF A FLAPPING BLOW FLY WING

2019 ◽  
pp. 10-18
Author(s):  
Can BEKER ◽  
Ali Emre TURGUT ◽  
Dilek Funda KURTULUŞ
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dynamic Analysis ◽  
Interaction Analysis ◽  
Blow Fly ◽  
Analysis Model ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Aeroelastic Analysis ◽  
Sinusoidal Input

In this study, 3D model of the bio-inspired blow fly wing Callphere Erytrocephala is created and aeroelastic analysis is performed to calculate its aerodynamical characateristic by use of numerical methods. In order to perform the flapping motion, a sinusoidal input function is created. The scope of this study is to perform aeroelastic analysis by syncronizing computational fluid dynamics (CFD) and structural dynamic analysis model and to investigate the unsteady lift formation on the aeroelastic flapping wing. Keywords: Micro air vehicle, Fluid-structure interaction analysis, Computational Fluid Dynamics, Structural dynamic analysis, Finite element analysis

scholarly journals Design Optimization for Structural-Acoustic Problems Using FEM-BEM

2002 ◽  
Author(s):  
Kyung K. Choi ◽  
Jun Dong ◽  
Nam Ho Kim
Keyword(s):  
Finite Element ◽  
Design Optimization ◽  
Boundary Element ◽  
Noise Level ◽  
Optimization Problems ◽  
Design Sensitivity ◽  
Response Analysis ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Structural Part

A structural-acoustic design optimization of a vehicle is presented using finite element and boundary element analyses. The steady-state dynamic behavior of the vehicle is calculated from the finite element frequency response analysis, while the sound pressure level within the acoustic cavity is calculated using the boundary element analysis. A reverse solution procedure is employed for the design sensitivity calculation using the adjoint variable method. An adjoint load is obtained from the acoustic boundary element re-analysis, while the adjoint solution is calculated from the structural dynamic re-analysis. The evaluation of pressure sensitivity only involves a numerical integration process for the structural part. Two design optimization problems are formulated and solved. It has been shown that the structural weight is saved when the noise level is maintained, and the weight needs to increase in order to reduce the noise level in the passenger compartment.

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