Straight-Build Assembly Optimization: A Method to Minimize Stage-by-Stage Eccentricity Error in the Assembly of Axisymmetric Rigid Components (Two-Dimensional Case Study)

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
T. Hussain ◽  
Z. Yang ◽  
A. A. Popov ◽  
S. McWilliam
Keyword(s):  
Central Axis ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Axis Ii ◽  
Straight Line ◽  
Third Stage ◽  
Assembly Procedure ◽  
Two Stages ◽  
Eccentricity Error

For assembly of rotating machines, such as machining tools, industrial turbomachinery, or aircraft gas turbine engines, parts need to be assembled in order to avoid internal bending of the geometric axis of the rotor to meet functional and vibration requirements. Straight-build assembly optimization is a way of joining parts together in order to have a straight line between the centers of the components. Straight-build assembly is achieved by minimizing eccentricity error stage-by-stage in the assembly. To achieve minimal eccentricity, this paper proposes three assembly procedures: (i) table-axis-build assembly by minimizing the distances from the centers of components to table axis; (ii) minimization of the position error between actual and nominal centers of the component; and (iii) central-axis-build assembly by minimizing the distances from the centers of components to a central axis. To test the assembly procedures, two typical assembly examples are considered using four identical rectangular components and four nonidentical rectangular components, respectively. Monte Carlo simulations are used to analyze the tolerance build-up, based on normally distributed random variables. The results show that assembly variations can be reduced significantly by selecting best relative orientation between mating parts. The results also show that procedures (i) and (ii) have the most potential to minimize the error build-up in the straight build of an assembly. For these procedures, the variation is reduced by 45% and 40% for identical and nonidentical components, respectively, compared to direct-build assembly. Procedure (iii) provides better performance than direct-build assembly for identical components assembly, while it gives smaller variation at the first two stages and larger variation at the third stage for nonidentical components assembly. This procedure could be used in an assembly with limited stages.

scholarly journals Design of experiments for verification of computational life prediction methods

2019 ◽  
Vol 18 (3) ◽  
pp. 143-154
Author(s):  
O. V. Samsonova ◽  
K. V. Fetisov ◽  
I. V. Karpman ◽  
I. V. Burtseva
Keyword(s):  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Turbine Engines ◽  
Prediction Methods ◽  
Gas Turbine Engines ◽  
Loading Conditions ◽  
Load History ◽  
Strain Behavior ◽  
Before And After ◽  
Two Stages

The failure of heavily loaded rotating parts of aviation gas turbine engines may bring about dangerous consequences. The life of such parts is limited with the use of computational and experimental methods. Computational life prediction methods that are used without carrying out life-cycle tests of engine parts or assemblies should be substantiated experimentally. The best option for verifying the computational methods is to use the results of cyclic tests of model disks. These tests make it possible to reproduce loading conditions and surface conditions that correspond to those of real disks, and the data on the load history and material properties make it possible to simulate stress-strain behavior of disks under test conditions by calculation. This paper shows the process of planning such tests. It is assumed that the tests will be carried out in two stages - before and after the initiation of a low-cycle fatigue crack. A number of criteria are formulated that the geometry of model disks and their loading conditions are to satisfy. Based on these criteria, model disks were designed and the conditions for their testing were selected.

Predictive Compressor Wash Optimization for Economic Operation of Gas Turbine

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Houman Hanachi ◽  
Jie Liu ◽  
Ping Ding ◽  
Il Yong Kim ◽  
Chris K. Mechefske
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Economic Losses ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Considerable Saving ◽  
Service Period ◽  
Power Deficit

Gas turbine engines (GTEs) are widely used for power generation, ranging from stationary power plants to airplane propulsion systems. Compressor fouling is the dominant degradation mode in gas turbines that leads to economic losses due to power deficit and extra fuel consumption. Washing of the compressor removes the fouling matter and retrieves the performance, while causing a variety of costs including loss of production during service time. In this paper, the effect of fouling and washing on the revenue of the power plant is studied, and a general solution for the optimum time between washes of the compressor under variable fouling rates and demand power is presented and analyzed. The framework calculates the savings achievable with optimization of time between washes during a service period. The methodology is utilized to optimize total costs of fouling and washing and analyze the effects and sensitivities to different technical and economic factors. As a case study, it is applied to a sample set of cumulative gas turbine operating data for a time-between-overhauls and the potential saving has been estimated. The results show considerable saving potential through optimization of time between washes.

Critical Components Life Update for Gas Turbine Engines: Case Study of an International Collaboration

2008 ◽  
Author(s):  
Wieslaw Beres ◽  
Donald Fread ◽  
Lesley Harris ◽  
Philip Haupt ◽  
Joanna Kappas ◽  
...  
Keyword(s):  
South Africa ◽  
Crack Initiation ◽  
Gas Turbine ◽  
Crack Growth ◽  
International Collaboration ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Management Procedures ◽  
Critical Components ◽  
Two Stages

The paper describes results of the international collaboration that led to revision of the declared lives for critical components of a turbo-prop gas turbine engine. Four nations contributed to the program—Australia, Canada, USA and South Africa under the auspices of a Component Improvement Program led by the Original Equipment Manufacturer (OEM). This international collaboration was initiated as a result of the decrease in the declared life for some critical components of this engine by the OEM. The core of the program consisted of a detailed stress analysis performed in South Africa, and spin rig testing of selected life-limited, rotating turbine components—two stages of discs and two stages of spacers—performed in Australia and Canada. The general objectives of the program were to provide more accurate low cycle fatigue crack initiation data and to verify crack growth life analysis techniques using advanced 2D and 3D finite element analyses and spin rig testing for selected components. The crack initiation results are used to improve the life management procedures. Since the OEM does not recommend using life limits that exceed the safe crack initiation life of the rotating turbine components, the crack growth analysis results are used only for risk assessment and risk management by the engine operators. The basis of analytical techniques used for preparing the tests as well as the testing procedures are described. In addition, the development of NDE (Non Destructive Evaluation) methods and the inspections of these components during and after the tests are discussed. The economical benefits of such an international collaboration are demonstrated. The uniqueness of this approach to life revision of critical components of gas turbine engines, particularly for engines that have been in operation for many years, includes close cooperation of an international team of the engine manufacturer, the major engine users and their respective scientific organizations. In addition, a significant amount of operational experience that has been accumulated by the OEM, has allowed for verification of the spin rig test results.

De-Oiler System for Improved Oil Containment

2006 ◽  
Author(s):  
William G. Sheridan ◽  
Sarah T. Swayze ◽  
J. Axel Glahn
Keyword(s):  
Gas Turbine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Mechanical Seals ◽  
Idle Speed ◽  
Critical Design ◽  
Safety And Reliability ◽  
Moderate Power ◽  
Oil Mist

Oil containment is a critical design requirement that affects overall system safety and reliability of gas turbine engines. This paper examines a new method to enhance oil containment by use of an improved de-oiler that creates a favorable bearing compartment differential pressure environment even at low power settings. Typically gas turbine engines require seals to contain oil within the bearing compartment. These seals, both contacting and non-contacting configuration styles, rely on secondary airflow to buffer the sealing interface and force oil mist and droplets back into the compartment. This is not difficult to achieve at high or moderate power conditions since there is generally sufficient air flow and pressure available to meet the sealing requirements. However, at idle conditions, the engine low-pressure compressor (LPC) may not turn fast enough to produce sufficient airflow to buffer the seals. To address these concerns the authors propose a method where the de-oiler creates a vacuum at idle speed, which results in favorable compartment seal differential pressures and also acts as a restrictor at higher speeds, where limiting the contact pressure and increasing the service life of mechanical seals become desirable design goals. The paper will examine a specific case study with both analytical and experimental results.

scholarly journals A CASE STUDY OF VIBRATION FAULT DIAGNOSIS APPLIED AT ROLLS-ROYCE T-56 TURBOPROP ENGINE

Aviation ◽  
2020 ◽  
Vol 23 (3) ◽  
pp. 78-82
Author(s):  
Christos Skliros
Keyword(s):  
Fault Diagnosis ◽  
Fault Detection ◽  
Gas Turbine ◽  
Fault Detection And Isolation ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Root Cause ◽  
Significant Challenge ◽  
Turboprop Engine

Gas turbine engines include a plethora of rotating modules, and each module consists of numerous components. A component’s mechanical fault can result in excessive engine vibrations. Identification of the root cause of a vibration fault is a significant challenge for both engine manufacturers and operators. This paper presents a case study of vibration fault detection and isolation applied at a Rolls-Royce T-56 turboprop engine. In this paper, the end-to-end fault diagnosis process from starting system faults to the isolation of the engine’s shaft that caused excessive vibrations is described. This work contributes to enhancing the understanding of turboprop engine behaviour under vibration conditions and highlights the merit of combing information from technical logs, maintenance manuals and engineering judgment in successful fault diagnosis.

Gas Screen in Components of Gas Turbine Engines

1997 ◽  
Vol 28 (7-8) ◽  
pp. 536-542
Author(s):  
A. A. Khalatov ◽  
I. S. Varganov
Keyword(s):  
Gas Turbine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Gas Screen

Potential Application of Composite Materials to Future Gas Turbine Engines

1988 ◽  
Author(s):  
James C. Birdsall ◽  
William J. Davies ◽  
Richard Dixon ◽  
Matthew J. Ivary ◽  
Gary A. Wigell
Keyword(s):  
Composite Materials ◽  
Gas Turbine ◽  
Potential Application ◽  
Turbine Engines ◽  
Gas Turbine Engines

PYROMET ALLOY CTX-1

Alloy Digest ◽  
1997 ◽  
Vol 46 (5) ◽  
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
High Strength ◽  
Heat Treating ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Thermal Fatigue Resistance ◽  
Temperature Performance ◽  
Hot Work Die ◽  
Pressure Hydrogen ◽  
Hot Hardness

Abstract Pyromet CTX-1 is a high-strength, precipitation-hardenable superalloy exhibiting a low coefficient of thermal expansion and high strength up to about 1200 deg F. The alloy possesses high hot hardness and good thermal fatigue resistance. Its applications include components for gas turbine engines, hot-work die applications and high-pressure hydrogen environments. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: FE-56. Producer or source: Carpenter. Originally published February 1976, revised May 1997.

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