Rotor-Dynamics of Different Shaft Configurations for a 6 kW Micro Gas Turbine for Concentrated Solar Power

2016 ◽  
Author(s):  
A. Arroyo ◽  
M. McLorn ◽  
M. Fabian ◽  
M. White ◽  
A. I. Sayma
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Dynamic Models ◽  
Solar Power ◽  
Critical Issue ◽  
Rotor Dynamics ◽  
Mode Shapes ◽  
Concentrated Solar Power ◽  
Element Analysis ◽  
Rotor Dynamic

Rotor-dynamics of Micro Gas Turbines (MGTs) under 30 kW have been a critical issue for the successful development of reliable engines during the last decades. Especially, no consensus has been reached on a reliable MGT arrangement under 10 kW with rotational speeds above 100,000 rpm, making the understanding of the rotor-dynamics of these high speed systems an important research area. This paper presents a linear rotor-dynamic analysis and comparison of three mechanical arrangements of a 6 kW MGT intended for utilising Concentrated Solar Power (CSP) using a parabolic dish concentrator. This application differs from the usual fuel burning MGT in that it is required to operate at a wider operating speed range. The objective is to find an arrangement that allows reliable mechanical operation through better understanding of the rotor dynamics for a number of alternative shaft-bearings arrangements. Finite Element Analysis (FEA) was used to produce Campbell diagrams and to determine the critical speeds and mode shapes. Experimental hammer tests using a new approach based on optical sensing technology were used to validate the rotor-dynamic models. The FEA simulation results for the natural frequencies of a shaft arrangement were within 5% of the measurements, while the deviation for the shaft-bearings arrangement increased up to 16%.

Retrofitting Gas Turbine Units Parabolic Trough Concentrated Solar Power for Sustainable Electricity Generation

2018 ◽  
Author(s):  
Wael Alnahdi ◽  
Sara Al Shamsi ◽  
Wafaa Alantali ◽  
Shaikha Al Shehhi ◽  
Mohamed I. Hassan Ali
Keyword(s):  
Gas Turbine ◽  
Thermal Energy ◽  
Gas Turbines ◽  
Solar Power ◽  
Weather Conditions ◽  
Heat Transfer Fluid ◽  
Concentrated Solar Power ◽  
Turbine Capacity ◽  
Sustainable Electricity ◽  
Steam Superheating

Shamsl is hybrid solar/natural-gas concentrated solar power (CSP) plants. The plant is also integrated with a booster gas-fired-heaters for steam superheating. In addition to direct fire-heaters to the heat transfer fluid (HTF) for supplying thermal energy during the night or whenever the solar irradiance level is dimmed. However, there is a more sustainable way to avoid power-generation-outages caused by transient weather conditions without a significant plant reconstruction, i.e. integration with gas turbines. In this study, a thermodynamic model of Shamsl integration with gas turbines is developed to investigate the gas turbine capacity and the exergitic efficiency of the supplied gas with and without the gas turbine involvement. The HTF heaters will receive the needed thermal energy from the gas turbines exhaust gases instead of the direct fire-heater (case1). Another potential is replacing the booster fire heaters with the gas turbine system as well. (case2). A parametric study is conducted to determine the size and the requirements of a gas turbine system for the specified power target demand in addition to a feasibility study for the proposed system. The results showed that using two gas turbines for the HTF heater significantly improved the overall efficiency and reduces the CO2 emission. Replacing the booster heater with two gas turbines improves the efficiency up to excess air factor of 2.5.

Squeeze film dampers supporting high-speed rotors: Rotordynamics

2020 ◽  
pp. 135065012092208
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Gas Turbines ◽  
High Speed ◽  
Squeeze Film ◽  
Jet Engines ◽  
Transient Vibration ◽  
Element Analysis ◽  
Squeeze Film Damper ◽  
The Time Domain

This work develops a finite element based multi-mass flexible rotor model for theoretical investigation of the influence of the squeeze film damper lubricant inertia on the unbalance-induced steady-state and transient vibration amplitudes of high speed turbomachinery. The rotordynamic model is developed by applying the principles of finite element analysis to discretize the rotor components, including the rotor shaft and disk, into local elements with mass, stiffness, and gyroscopic matrices. Subsequently, the local matrices are assembled together to develop the global model of the rotordynamic system. The influence of squeeze film damper lubricant inertia is incorporated into the model by using short-length cavitated damper models with retaining springs executing circular-centered orbits. Additionally, the rotordynamic model incorporating the nonlinear squeeze film damper models is iteratively solved in the time domain by applying a predictor-corrector transient modal integration numerical method and the steady-state and transient motions of the rotor system are investigated under different rotor and squeeze film damper parameters. The results of the study verify the substantial influence of squeeze film damper lubricant inertia on attenuating the vibrations of high-speed turbomachinery. Furthermore, the developed rotordynamic model delivers an efficient and powerful platform for the analysis of high-speed turbomachinery, including jet engines and gas turbines.

FEM Analysis of a Diesel Engine’s Cylinder Head

2012 ◽  
Vol 490-495 ◽  
pp. 3023-3026
Author(s):  
Shao Zhong Jiang
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Cylinder Head ◽  
High Speed ◽  
Structural Characteristics ◽  
Fem Analysis ◽  
Mode Shapes ◽  
Element Analysis ◽  
Frequency Distributions ◽  
And Control

The article aims at the cylinder head used in a high speed and higher-power diesel engine. In order to obtain the vibration characteristics and vibration frequency distributions. By means of modal analysis technology and finite element method (FEM), structural characteristics of the cylinder head using modal analysis is investigated. Firstly, a physical model of the cylinder head is built. Through the comparison of all the modal analysis results with different meshing densities, a tetrahedron ten-node element with length of 30mm is selected. Then finite element analysis of the model is taken by FEM software. The cylinder head’s modal parameters namely its natural frequency are calculated and its mode shapes are identified. The results can provide basis for the engine’s dynamic analysis and control of the diesel engine’s noise

scholarly journals Critical Speeds for Carbon/Epoxy Composite Rotors in Spacecraft Energy Storage Applications

2011 ◽  
Vol 471-472 ◽  
pp. 37-42 ◽  
Author(s):  
Renuganth Varatharajoo ◽  
Faizal Mustapha ◽  
Dayang Laila Abang Abdul Majid ◽  
Rizal Zahari ◽  
Ralph Kahle
Keyword(s):  
Energy Storage ◽  
High Speed ◽  
Mode Shapes ◽  
Stress Distributions ◽  
Element Analysis ◽  
Rotor Design ◽  
Energy Storage Application ◽  
Triple Layer ◽  
Layer Composite ◽  
Rotor Model

A numerical investigation to optimize the carbon/epoxy multi layer composite rotor is performed for the spacecraft energy storage application. A high-speed double and triple layer rotor design is proposed and different composite materials are tested to achieve the most suitable recipe. First, analytical rotor evaluation was performed in order to establish a reliable numerical composite rotor model. Subsequently, finite element analysis is employed in order to optimize the double and triple layer composite rotors. Then, the modal analysis was carried out to determine the rotor natural frequencies. The rotor stress distributions and the rotor mode shapes show that a safe operational regime below 46, 000 rotations per minute is achievable.

The Vibration Fault Diagnosis of High-Speed Rotating Machinery Based on the Simulation

2011 ◽  
Vol 317-319 ◽  
pp. 2172-2176
Author(s):  
Ya Bin Tian ◽  
Xu Yi Qi ◽  
Guo Bin Liang
Keyword(s):  
Fault Diagnosis ◽  
High Speed ◽  
Simulation Analysis ◽  
Rotor Dynamics ◽  
Rotating Machinery ◽  
Common Cause ◽  
Local Structures ◽  
Equipment Failures ◽  
Rotor Dynamic ◽  
Reliable Basis

Many researchers explore the issue about how to predict equipment failures and how to analyze the cause of the failures and to solve them. The mass imbalance is the most common cause of the malfunction of the rotating machinery. Based on the theory of rotor dynamics, we can diagnose the failure and its causes more accurately by applying the software to doing simulation analysis of characteristics of rotor dynamic. And, it provides the reliable basis for the further solutions of the failures. In this paper, we analyze a corporation's compressor with abnormal vibration in operation, and finding out the reasons for its vibration. According to the calculated results, we transformed the local structures of its rotor. After transformation, the compressor runs smoothly.

Rotor Dynamic Modeling of Gears and Geared Systems

2013 ◽  
Author(s):  
Jason A. Kaplan ◽  
Saeid Dousti ◽  
Paul E. Allaire ◽  
Bradley R. Nichols ◽  
Timothy W. Dimond ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Forced Response ◽  
Drive Train ◽  
Mode Shapes ◽  
Element Formulation ◽  
Resonant Frequencies ◽  
Industrial Drive ◽  
Rotor Dynamic

The ability to accurately predict rotating machine resonant frequencies and to assess their stability and response to external forces is crucial from a reliability and preventive maintenance perspective. Resonant frequencies and forced response become more difficult to predict when additional complicated components such as gearboxes are present in the rotor system. Gearbox dynamics contain many complex interactions and many of the simplifying assumptions provided in the literature do not apply to most geared systems. A finite element formulation of the gearbox, which couples the axial, lateral, and torsional degrees-of-freedom of the low and high-speed shafts, is developed. It has the capability to apply to a wide variety of both spur and helical geared systems and is sufficiently robust to account for arbitrary orientation angles between the parallel shafts. This study presents a rotor dynamic analysis of an industrial drive-train consisting of a steam turbine, herringbone gearbox, and a generator using 1-D Timoshenko beam elements. The rotor dynamic analysis consists of the calculation of the damped natural frequencies, mode shapes, and provides insight into the stability of the industrial drive-train.

Prediction of Structural Supports Influence on Rotating Machinery Dynamics

2017 ◽  
Author(s):  
Leonid Moroz ◽  
Leonid Romanenko ◽  
Roman Kochurov ◽  
Evgen Kashtanov
Keyword(s):  
Support System ◽  
System Analysis ◽  
Element Model ◽  
Critical Issue ◽  
Rotor Dynamics ◽  
Mode Shapes ◽  
Response Analysis ◽  
Research Activities ◽  
Rotor Bearing ◽  
Rotor Model

Rotor lifetime and safety primarily depend on the level of rotor vibration. In order to avoid unwanted consequences for the plant due to rotor damage and to meet the highest requirements of design reliability, accurate rotor dynamic predictions are mandatory. Having the correct rotor model is a critical issue in dynamics prediction. Often research activities are focused only on the rotor-bearing system analysis. However, generally, the whole system, which includes the rotor, bearings, casing and structural supports should be considered. Special attention should be paid to the influence of structural supports which reveals when the rotor is supported by ball bearings because of low damping and high bearing stiffness. The approach presented in this paper allows us to simulate the influence of structural supports on rotor dynamics response and as a result, the full picture of rotor-bearing-support system resonances can be analyzed to avoid potential problems. The methodology is based on support vibrations modal reduction technics. According to the approach, the natural frequencies and their mode shapes should be calculated for the separate support structure applying a three-dimensional finite element model and the relative displacements at bearing location points are measured. Supports’ normalized modal characteristics (modal mass and modal stiffness) for each vibration mode should then be imported in a rotor dynamics algorithm for rotor unbalance response analysis. The approach allows for simulation of different types of support structures such as bearing pedestals, steel foundations, tabletop-type foundation, frame and pipe supports of arbitrary geometry, and so on. Validation based on the Jeffcott rotor model is presented. The current methodology has been applied to a single-stage compressor’s rotor-bearing-support system which was manufactured and commissioned. The results of the simulations are discussed.

An Integrated Approach for the Predictions of the Workpiece Vibrations During Machining of Aerospace Structure: Numerical and Experimental Validation

2012 ◽  
Author(s):  
Mouhab Meshreki ◽  
József Kövecses ◽  
Helmi Attia
Keyword(s):  
High Speed ◽  
Dynamic Models ◽  
Force Measurement ◽  
Integrated Approach ◽  
Analytical Models ◽  
Prediction Errors ◽  
Continuous Change ◽  
Element Analysis ◽  
Analytical Methodology ◽  
Thin Walled

Accurate predictions of the workpiece vibrations during high speed machining of aerospace structural components is a critical issue since it affects the accuracy of the final part. For fixture design purposes, and for force predictions, the computational efficiency of the dynamic models predicting the workpiece vibrations is a crucial factor since it affects the cycle time for the design and optimization of the fixtures. Most of the available dynamic models are based on computationally prohibitive techniques, such as finite element analysis. In this work, an integrated approach, based on recently developed semi-analytical models, is presented for the analysis of the effect of the fixture layout on the dynamics of thin-walled structures while taking into account the continuous change of thickness of the workpiece, and the effect of rigid and deformable fixture supports. The developed approach is based on plate models with holonomic constraints and finite stiffness springs. This approach, together with all the developed models and formulations are validated numerically for different workpiece geometries and various types of loading. An experimental study has been performed to validate this approach through the machining of thin-walled components. It was found that this approach led to prediction errors within 10% and more than 20 times reduction in the computation time. The challenge of filtering the effect of the dynamics of the force measurement system from the measured signals was overcome by developing a new hybrid semi-analytical methodology for accurate measurement of the machining forces.

scholarly journals Verification of Vibration of Composite Beam with Crack by using Finite Element Method and Experimental Method

2019 ◽  
Vol 8 (4) ◽  
pp. 11621-11625
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Composite Beam ◽  
Vibration Analysis ◽  
High Speed ◽  
Experimental Result ◽  
Mode Shapes ◽  
Element Analysis ◽  
The Status ◽  
Weight Structures

This paper presents evaluation of analytical and experimental result discussion for vibration analysis of composite beam with crack. Beams and beam like elements are principal constituents of many mechanical structures and used widely in high speed machinery, aircraft and light weight structures. Finite Element Analysis is carried out using ANSYS 14.5. The model of beam is prepared and used for Finite Element Analysis. The model analysis is used to determine the natural frequencies and mode shapes of a structure. The experimental analysis is conducted by using a Fast Fourier Transform (FFT) device which is used to detect the potential faults and checking the status of the machine through the vibration analysis.

A hybrid (permanent magnet and foil) bearing set for complete passive levitation of high-speed rotors

2016 ◽  
Vol 231 (20) ◽  
pp. 3679-3689 ◽  
Author(s):  
Siddappa I Bekinal ◽  
Sadanand S Kulkarni ◽  
Soumendu Jana
Keyword(s):  
Permanent Magnet ◽  
High Speed ◽  
Thrust Bearing ◽  
System Response ◽  
Element Analysis ◽  
Foil Bearings ◽  
Hybrid Bearing ◽  
The Mathematical Model ◽  
Rotor Dynamic ◽  
Dynamic Data Acquisition

This paper presents the design and development of a hybrid bearing set for complete passive levitation of a typical rotor. A hybrid bearing set consists of permanent magnet thrust bearing and radial discrete bump foil bearings. The permanent magnet thrust bearing is made up of three pairs of ring magnets arranged in rotation magnetized direction. The mathematical model to determine the force and stiffness in rotation magnetized direction configuration is presented using Coulombian model and vector approach. Bump foil bearings are designed and developed for rotor weight to provide the radial support to the rotor system. The proposed bearing set with rotor is analysed using finite element analysis for rotor dynamic characteristics. The experiments are conducted on the fabricated rotor-bearing configuration by rotating the rotor up to the speeds of 40,000 r/min. The system response is acquired using advanced rotor-dynamic data acquisition system. The experimental results show that the rotor is completely airborne and stable at the desired speed.

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