Design and Tests of a New Damper for a Gas Turbine Thin-Shell Duct

2021 ◽  
Author(s):  
Serena Gabriele ◽  
Paolo Di Sisto ◽  
Giuseppe Del Vescovo ◽  
Conti Simone
Keyword(s):  
Gas Turbine ◽  
Thin Shell ◽  
Flow Path ◽  
Forced Response ◽  
Operating Conditions ◽  
Internal Space ◽  
Gas Generator ◽  
Fea Model ◽  
Power Turbine ◽  
Harmonic Analyses

Abstract Gas turbine (GT) liners, transition ducts and exhaust diffusers are large thin-shell ducts bounded by two barrels, typically characterized by multiple natural frequencies inside the operating speed range of the engine rotor. In most applications, GT ducts are supported on one side only and they are free to expand inside the gas turbine so to avoid thermal distresses. The GT ducts are typically damped structures able to prevent high cycles fatigue failures. Damping is provided by sliding features as insulation or bolted joints. This paper describes the redesign of a transition duct (TD) after it was discovered that in some operating conditions, duct could crack for high cycle fatigue (HCF). The TD connects the flow path of the gas generator turbine with the flow path of the power turbine. The new TD has been made more robust, but it has also been equipped of dampers capable to operate at high temperature. Starting from the analyses of field data, a predictive FEA model has been developed and validated. After a deep investigation of the TD modes that could be excited by flow path and/or by rotor vibrations, it was decided to add two dampers, one for each barrel of the TD. Due to internal space limitations, a new type of damper has been designed for the external barrel. Both dampers have been sized using FEA. Harmonic analyses rather than forced response transient analyses have been performed so to verify the effectiveness of the new design. In the simulations, dampers have been replaced by harmonic forces able to reproduce the friction force of the dampers. Validation of the method and damper calibration has been done by performing lab tests and full-size TD tests.

Unbalance Response of a Two Spool Gas Turbine Engine With Squeeze Film Bearings

1981 ◽  
Author(s):  
E. J. Gunter ◽  
D. F. Li ◽  
L. E. Barrett
Keyword(s):  
Gas Turbine ◽  
Nonlinear Effects ◽  
Forced Response ◽  
Squeeze Film ◽  
Gas Generator ◽  
Main Bearing ◽  
Resonant Condition ◽  
Turbine Engine ◽  
Generator Rotor ◽  
Power Turbine

This paper presents a dynamic analysis of a two-spool gas turbine helicopter engine incorporating intershaft rolling element bearings between the gas generator and power turbine rotors. The analysis includes the nonlinear effects of a squeeze film bearing incorporated on the gas generator rotor. The analysis includes critical speeds and forced response of the system and indicates that substantial dynamic loads may be imposed on the intershaft bearings and main bearing supports with an improperly designed squeeze film bearing. A comparison of theoretical and experimental gas generator rotor response is presented illustrating the nonlinear characteristics of the squeeze film bearing. It was found that large intershaft bearing forces may occur even though the engine is not operating at a resonant condition.

scholarly journals Development of the PGT 25 High Efficiency Gas Turbine: Part 2 — Aerodynamic Design and Performance

1984 ◽  
Author(s):  
E. Benvenuti ◽  
B. Innocenti ◽  
R. Modi
Keyword(s):  
Gas Turbine ◽  
High Efficiency ◽  
Performance Testing ◽  
Operating Conditions ◽  
Aerodynamic Design ◽  
Direct Drive ◽  
Gas Generator ◽  
Full Load ◽  
Wide Range ◽  
Overall Performance

This paper outlines parameter selection criteria and major procedures used in the PGT 25 gas turbine power spool aerodynamic design; significant results of the shop full-load tests are also illustrated with reference to both overall performance and internal flow-field measurements. A major aero-design objective was established as that of achieving the highest overall performance levels possible with the matching to latest generation aero-derivative gas generators; therefore, high efficiencies were set as a target both for the design point and for a wide range of operating conditions, to optimize the turbine’s uses in mechanical drive applications. Furthermore, the design was developed to reach the performance targets in conjunction with the availability of a nominal shaft speed optimized for the direct drive of pipeline booster centrifugal compressors. The results of the full-load performance testing of the first unit, equipped with a General Electric LM 2500/30 gas generator, showed full attainment of the design objectives; a maximum overall thermal efficiency exceeding 37% at nominal rating and a wide operating flexibility with regard to both efficiency and power were demonstrated.

LM9000 Passive Clearance Control (PCC)

2020 ◽  
Author(s):  
Simone Marchetti ◽  
Duccio Nappini ◽  
Roberto De Prosperis ◽  
Paolo Di Sisto
Keyword(s):  
Control System ◽  
Low Pressure ◽  
Industrial Applications ◽  
Flow Path ◽  
Operating Conditions ◽  
Low Pressure Turbine ◽  
Power Turbine ◽  
Extensive Test ◽  
First Time ◽  
Clearance Control

Abstract This paper describes the design of the Free Power Turbine (FPT) of the LM9000, in particularly the design of its Passive Clearance Control (PCC) system. The LM9000 is the aero-derivative version of the GE90-115B jet engine. Its core engine has many common parts with the GE90; what differs is the booster (low pressure compressor) and the lower pressure turbine (LPT). The booster of the LM9000 is without fan because the engine is not used to provide thrust but torque only, subsequently it has a new flow path [5]. The LPT has instead been replaced by an intermediate pressure turbine (IPT) and by the FPT. The IPT drives the booster, while the FPT is a free low-pressure turbine designed for both power generation and mechanical drive industrial applications, including LNG production plants. Due to its different application, the LM9000 FPT flow path differs sensibly from the GE90 LPT, however as the GE90 it is provided of a clearance control system that cools the casing in order to reduce its radial deflection. It is not the first time that a clearance control system has been used in industrial applications; in GE aero-derivative power turbines is already present in the LM6000 and LMS100. Design constraints, system complexity, high environment variability because the PCC is located outside the GT, harsh environments and long periods of usage still make the design of this component challenging. The design of the PCC has been supported by extensive heat transfer and mechanical simulations. Each PCC component has been addressed with a dedicated life calculation and all the blade and seal clearances have been estimated for all the operating conditions of the engine. Simulations have been validated by an extensive test campaign performed on the first engine.

Hydro Francis Runner Stability and Forced Response Calculations

2019 ◽  
Author(s):  
Charles Seeley ◽  
Sunil Patil ◽  
Andy Madden ◽  
Stuart Connell ◽  
Gwenael Hauet ◽  
...  
Keyword(s):  
Large Scale ◽  
Forced Response ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Symmetric Model ◽  
Validation Data ◽  
Fea Model ◽  
Forcing Function ◽  
Cyclic Symmetric ◽  
Work Done

Abstract Hydroelectric power generation accounts for 7% of the total world electric energy production. Francis turbines are often employed in large-scale hydro projects and represent 60% of the total installed base. Outputs up to 800 MW are available and efficiencies of 95% are common. Cost, performance, and design cycle time are factors that continue to drive new designs as well as retrofits. This motivates the development of more sophisticated analysis tools to better assess runner performance earlier in the design phase. The focus of this paper is to demonstrate high fidelity and time-efficient runner damping and forced response calculations based on one-way fluid-structure interaction (FSI) using loosely coupled commercial finite element analysis (FEA) and computational fluid dynamics (CFD) codes. The runner damping is evaluated based on the work done by the fluid on the runner. The calculation of the work first involves determining the runner mode shapes and natural frequencies using a cyclic symmetric FEA model with structural elements to represent the runner hardware, and acoustic fluid elements to represent the mass loading effect of the fluid. The mode shapes are then used in a transient CFD calculation to determine the damping which represents the work done by the fluid on the runner. Positive damping represents stability from flutter perspective while negative damping represents unstable operating conditions. A transient CFD calculation was performed on a runner to obtain engine order forcing function from upstream stationary vanes. This unsteady forcing function was mapped to the FEA model. Care is taken to account for the proper inter-blade phase angle on the cyclic symmetric model. The hydraulic damping from flutter calculations was also provided as input to the forced response. The forced response is then determined using this equivalent proportional damping and modal superposition of the FEA model that includes both the structural and acoustic elements. Results of the developed analysis procedure are presented based on the Tokke runner, that has been the basis of several studies through the Norwegian HydroPower Center. Unique features of the workflow and modeling approaches are discussed in detail. Benefits and challenges for both the FEA model and the CFD model are discussed. The importance of the hydraulic damping, that is traditionally ignored in previous analysis is discussed as well. No validation data is available for the forced response, so this paper is focused on the methodology for the calculations.

Capacity Matching of Aeroderivative Gas Generator With Free Power Turbine: Challenges, Uncertainties, and Opportunities

2019 ◽  
Author(s):  
Deepak Thirumurthy ◽  
Jose Carlos Casado Coca ◽  
Kanishka Suraweera
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Systems Approach ◽  
Gas Generator ◽  
Performance Guarantees ◽  
Design Variables ◽  
Performance Trends ◽  
Power Turbine ◽  
Parameter Matching ◽  
Turbine Capacity

Abstract For gas turbines with free power turbines, the capacity or flow parameter matching is of prime importance. Accurately matched capacity enables the gas turbine to run at its optimum conditions. This ensures maximum component efficiencies, and optimum shaft speeds within mechanical limits. This paper presents the challenges, uncertainties, and opportunities associated with an accurate matching of a generic two-shaft aeroderivative HP-LP gas generator with the free power turbine. Additionally, generic performance trends, uncertainty quantification, and results from the verification program are also discussed. These results are necessary to ensure that the final free power turbine capacity is within the allowable range and hence the product meets the performance guarantees. The sensitivity of free power turbine capacity to various design variables such as the vane throat area, vane trailing edge size, and manufacturing tolerance is presented. In addition, issues that may arise due to not meeting the target capacity are also discussed. To conclude, in addition to design, analysis, and statistical studies, a system-of-systems approach is mandatory to meet the allowed variation in the free power turbine capacity and hence the desired gas turbine performance.

Development US Navy Gas Turbine Vibration Analysis Expertise: LM2500 Vibration and Trim Balance

2012 ◽  
Author(s):  
Bruce D. Thompson ◽  
Jurie Grobler
Keyword(s):  
Gas Turbine ◽  
Turbine Rotor ◽  
Gas Generator ◽  
Engine Operation ◽  
Engine Design ◽  
Power Turbine ◽  
Us Navy ◽  
Continued Use ◽  
Integrated Performance ◽  
Mean Time

Although generally reliable in-service and with an ever increasing mean time between removal, it was identified in the mid to late 1980’s that the LM2500 gas turbine in US Navy service had a problem with self generated vibration; this was principally due to imbalance in the gas generator or power turbine rotor, however, other non-synchronous sources for vibration were discovered to be important as well. The initial method for resolving this problem was to remove and repair, at a depot, the engines that exceeded the in-service alarm level. This turned out to be a very expensive approach and it was found that most engines that had excessive vibration levels in other respects (performance, etc.) were perfectly acceptable for continued use without repair. Raising the vibration alarm level was tried for a time. However, it became clear that prolonged engine operation with higher levels of vibration were detrimental to the mechanical integrity of the engine. This paper discusses the systematic approach developed to reduce LM2500 self generated vibration levels. This included monitoring system improvements, engine design & hardware improvements and the development and implementation of in-place trim balance. This paper also discusses some of the analysis and practical difficulties encountered reducing and maintaining low LM2500 vibration levels through trim balance and by other means. Also discussed is the present implementation of remotely monitoring LM2500 operating parameters, in particular vibration, through the Integrated Performance Analysis Reports (IPAR) and the Maintenance Engineering Library Server (MELS).

Aerodynamic Design of a Power Turbine for an Aircraft Derivative Marine Gas Turbine

1988 ◽  
Vol 110 (1) ◽  
pp. 104-109 ◽  
Author(s):  
Guiming Ji ◽  
Zengxiang Tan ◽  
Mingchang Zhang
Keyword(s):  
Gas Turbine ◽  
Design Methodology ◽  
Aerodynamic Characteristics ◽  
Engineering Practice ◽  
Variable Geometry ◽  
Aerodynamic Design ◽  
Gas Generator ◽  
Power Turbine ◽  
Calculation Results ◽  
Radial Equilibrium

Based on the aerodynamic design and development of a power turbine for an aircraft derivative marine gas turbine in our engineering practice and taking account of the specific features of a marinization effort, this paper describes the design approach and aerodynamic characteristics of the said power turbine, including parameter selection, design methodology, comparison of flow calculation results obtained by simple radial equilibrium and full radial equilibrium method, and a versatile design of the power turbine capable of rendering two power ratings. Also described is the use of variable geometry stator blades to accommodate a small amount of adjustment to the gas generator outlet parameters.

scholarly journals Gas Turbine Compressor Unit Repowering

1996 ◽  
Author(s):  
Joe S. Taylor
Keyword(s):  
Gas Turbine ◽  
Centrifugal Compressor ◽  
Gas Storage ◽  
Emission Rates ◽  
Gas Generator ◽  
Reciprocating Engine ◽  
Power Turbine ◽  
Macomb County ◽  
The Cost ◽  
Gas Turbine Compressor

This paper presents how a major U.S. gas transmission and storage company restored gas storage peaking capacity by repowering obsolete gas turbine compressor units. Consumers Power Company’s Ray Field located in Macomb County, Michigan, USA, was developed as a 44 BCF working capacity gas storage field in 1966. Due to the high deliverability, the field is operated as a peaking reservoir, handling rates as high as 500 MMCFD on injection and 1,200 MMCFD on withdrawal. Ten (10) 2,750 horsepower gas turbine driven 4-stage centrifugal compressor units were installed in the mid to late 1960’s at the field. The compression is operated 2, 4 and 8 stage, as needed, to cover storage pressures of 450 to 1800 psig. Each centrifugal compressor is driven by a Pratt Whitney (PW) GG-12 Gas Generator firing into a Cooper-Bessemer (CB) RT-27 Power Turbine. By 1980 parts and maintenance services for the PW GG-12 Gas Generator became very expensive to non-existent. Aircraft use of the GG-12 (JT-12) had been phased out. Consumers Power, with 13 of these turbines on their system, was becoming the only remaining user. In the mid 1980’s four (4) of the Ray Field gas turbine compressor units were replaced with two (2) 6,000 horsepower reciprocating engine compressor units. These replacements maintained the deliverability of the field and provided salvageable engines and other parts to maintain the six (6) remaining turbines. However, by 1993 maintenance parts returned as a major problem as well as unit availability on the 6 remaining turbine units. In 1994 Consumers Power committed to a gas turbine unit repowering program as the preferred choice over unit replacement. Two (2) refurbished Solar Centaur T4500 Gas Turbine drives were purchased and installed to repower 2 of the obsolete turbine units. These installations have been very successful. Existing compressors, foundations, piping, coolers and auxiliary systems were re-used with only minor modification. The complete installed cost for repowering was about 33% of the cost experienced for replacement. Installation was completed within eight (8) months of project commitment. The low emission rates from the Solar SoLoNOx Combustors allowed short lead time (6 months) on air emissions permit. New sound attenuation enclosures met the new local noise ordinance and replaced equipment that had been a source of local complaint. PLC based controls improved reliability and flexibility of operation. The additional horsepower available from the T4500 Turbine (4,300 vs 2,750) allows for increased future capacity. Because of the success of the Ray Turbine Repowering Project, Consumers Power has committed to 2 more refurbished Solar Centaur T4500 Units to repower PW/CB Turbines at the St Clair Compressor Station. Solar is scheduled to delivery these 2 units by year-end 1995 for installation in 1996.

scholarly journals Investigating of Turbine Blades Geometrical Change Effects on Dynamic Performance of IGT-25 Gas Turbine

2019 ◽  
Author(s):  
Nima Zamani Meymian ◽  
Hossein Rabiei
Keyword(s):  
Gas Turbine ◽  
Mass Flow ◽  
Gas Flow ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Turbine Blades ◽  
Gas Generator ◽  
Air Compressor ◽  
Power Turbine ◽  
Geometrical Change

In the paper, the effect of gas generator turbine blades’ geometrical change has been studied on the overall performance of a twin-shaft 25MW gas turbine with industrial application, under dynamic conditions. Geometrical changes include change of thickness and height of gas generator turbine blades which in turn would result in the change in the mass flow rate of passing hot gas, as well as isentropic efficiency in each stage of the turbine. Gas turbine modeling in the paper is zero-dimensional and takes place with consideration of dynamic effects of volume on air compressor components, combustion chamber, gas generator turbine, power turbine, fuel system, as well as effects of heat transfer dynamics between blades, gas path, and effects of operators on inlet guide vanes, fuel valves, and air compressor discharge valve. In the mathematical model of each of the components, steady-state characteristics curves have been used, extracted from 3-Dimensional computational fluid dynamics (CFD). To do so, characteristic curves of the first and second stages of the four-stage turbine have been updated through 3-D fluid dynamic analysis so that the effect of geometrical changes in turbine blades would be applied. Results from effects of these changes on characteristics of transient gas flow including output power of gas generator turbine and power turbine, inlet and outlet temperatures of turbine stages, as well as air and fuel mass flow rates have been provided from the start-ups until reaching the nominal load would be achieved.

Condition Monitoring at Bulls Bridge Power Station

1983 ◽  
Author(s):  
K. N. Addrison ◽  
M. L. G. Hill
Keyword(s):  
Gas Turbine ◽  
Condition Monitoring ◽  
Gas Generator ◽  
Power Station ◽  
Power Turbine ◽  
Gas Generators

The Station chosen for the trial was Bulls Bridge Gas Turbine Station, sited near London Airport. (See Fig 1-1). Bulls Bridge contains 4, 70 MW sets; each 70 MW unit being powered by 4 Industrial Olympus gas generators, two at either end of a central alternator, (See Fig 1-2). At each end of the alternator, power is supplied via a clutch, to a shaft on which is mounted two power turbines, each driven by a single Olympus gas generator. Thus gas paths are separate between intake and final exhaust, and therefore each gas generator/power turbine assembly can be analysed without being unduly affected by associated plant.

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