Particularities of Blading Free Resonance Design for Heavy Duty Gas Turbines With Circumferential Rotor Grooves

2014 ◽  
Author(s):  
Igor Putchkov ◽  
Alexander Arkhipov ◽  
Valery Moskovskikh ◽  
Harald Kissel ◽  
Alexander Laqua
Keyword(s):  
Steady State ◽  
Gas Turbines ◽  
Natural Frequencies ◽  
Contact Spot ◽  
Heavy Duty ◽  
Blade Root ◽  
Lateral Contact ◽  
Start Up ◽  
Blade Frequency ◽  
Engine Start

Blades for heavy duty engines with circumferential rotor grooves are designed such that radial contact is made between the blade teeth and rotor groove at steady state operation conditions. However, sometimes circumferential contact arises between neighboring blade shanks, which is often caused by blade root /rotor thermal expansion. In this case, the radial fixation will give the lower limit of blade frequency band, and the circumferential will give the upper one. The Blade frequency difference between these two fixations might reach about 200–500 Hz depending on blade airfoil and root sizes. When some excitation source (e.g., vane passing frequencies caused by up-stream and down-stream vane counts) has a frequency level situated between blade frequencies caused by radial and circumferential contact, such a case is the subject of the proposed approach. In order to assess how strongly the blade might be fixed under different conditions and how long it might be in resonance during engine start-up and subsequent loading, a 3D elastic-plastic transient analysis and corresponding frequency calculation of blade/rotor assembly is used. At engine start-up the circumferential (lateral) contact between neighboring blade roots is insignificant, and the radial contact between the rotor and the blade is dominant. The lateral contact spot between neighboring blade attachments during start-up appears due to different rates of blade/rotor heating. Further heating leads to an increase of the lateral contact spot areas. The closing of these contact surfaces starts from the outer root edge and spreads toward the inner one, leading to an increase of assembly natural frequencies. Engine loading and further heating lead to the appearance of a circumferential gap between the surfaces, causing the lateral contact to disappear during steady state. The blade root coupling switches again to the usual radial contact state, with the corresponding reduction of natural frequencies. Because the described phenomenon might occur for some time during every start-up and shut-down (from several minutes to couple of hours), it becomes even more severe from a dynamics standpoint if some natural frequency of coupled system crosses the exciting frequency. Examples of assembly frequency tuning are presented.

Dynamic Simulation of Full Start-Up Procedure of Heavy Duty Gas Turbines

2001 ◽  
Author(s):  
J. H. Kim ◽  
T. W. Song ◽  
T. S. Kim ◽  
S. T. Ro
Keyword(s):  
Gas Turbines ◽  
Guide Vane ◽  
Inlet Guide Vane ◽  
Stable Operation ◽  
Heavy Duty ◽  
Operating Characteristics ◽  
Fully Implicit ◽  
Start Up ◽  
Full Speed ◽  
Stage Characteristic

A simulation program for transient analysis of the start-up procedure of heavy duty gas turbines for power generation has been constructed. Unsteady one-dimensional conservation equations are used and equation sets are solved numerically using a fully implicit method. A modified stage-stacking method has been adopted to estimate the operation of the compressor. Compressor stages are grouped into three categories (front, middle, rear), to which three different stage characteristic curves are applied in order to consider the different low-speed operating characteristics. Representative start-up sequences were adopted. The dynamic behavior of a representative heavy duty gas turbine was simulated for a full start-up procedure from zero to full speed. Simulated results matched the field data and confirmed unique characteristics such as the self-sustaining and the possibility of rear-stage choking at low speeds. Effects of the estimated schedules on the start-up characteristics were also investigated. Special attention was paid to the effects of modulating the variable inlet guide vane on start-up characteristics, which play a key role in the stable operation of gas turbines.

Handling Wind Variability Using Gas Turbines

2012 ◽  
Author(s):  
L. Branchini ◽  
H. Perez-Blanco
Keyword(s):  
Power Output ◽  
Gas Turbines ◽  
Wind Farm ◽  
Heavy Duty ◽  
Electrical Grid ◽  
Wind Variability ◽  
Turbine Performance ◽  
Start Up ◽  
Viable Solution ◽  
To Come

A significant amount of energy is expected to come from wind in the upcoming years. The variability and uncertainty of this power source needs to be managed by the grid operator. Electricity networks with wind energy need extra reserves to deal with the extra uncertainty associated with the presence of wind. This paper evaluates the possibility to couple a 1000 MW wind farm with gas turbines (GTs) to provide firm capacity to the grid with a reasonable investment. Taking into account two different days of wind production with one minute data, the study analyzes the possibility of integrating the wind power output with two different types of GTs (heavy duty and aeroderivative). GTs operational constrains are included in the model in order to correctly demonstrate how the wind variability stresses turbine performance, as it probably would in extreme cases. Limitations on GTs ramps rates and start–up time are considered for both, heavy duty and aeroderivatives. GTs power output profiles, ramp rates and fuel consumption for the selected days of analysis are shown. The results show that the integration between wind and gas turbines could be a viable solution to compensate wind variability and to accommodate the increasing wind penetration into the electrical grid.

scholarly journals Oscillation damping in the powertrain unit of transport vehicles

2019 ◽  
Vol 287 ◽  
pp. 01021
Author(s):  
Alexander Taratorkin ◽  
Viktor Derzhanskii ◽  
Igor Taratorkin
Keyword(s):  
Control System ◽  
Steady State ◽  
Supply System ◽  
Control Algorithms ◽  
System Control ◽  
Fuel Supply ◽  
Start Up ◽  
Oscillation Damping ◽  
Engine Start ◽  
Oscillatory Processes

The paper presents the results of an analytical experimental research of conditions for excitation of oscillatory processes in steady-state conditions and in the process of starting-up an engine equipped with a modern Common Rail fuel supply control system. Based on the results of mathematical simulation, the dependence of the dynamic torque amplitude on boosting acceleration during engine start-up and on the parameters of the elastic-dissipative coupling (connection) of the engine with the transmission is analyzed. It establishes the rationale for a possibility of optimizing the fuel supply system control algorithms for a modern diesel engine, taking into consideration the dependence of the process on the properties of the transmission and the peculiarities of its operation.

Dynamic Model of a Two Shaft Heavy-Duty Gas Turbine With Variable Geometry

1995 ◽  
Author(s):  
Pierluigi Nava ◽  
Valter Quercioli ◽  
Tiziano Mammoli
Keyword(s):  
Dynamic Model ◽  
Gas Turbines ◽  
Dynamic Models ◽  
Stable Operation ◽  
Variable Geometry ◽  
Heavy Duty ◽  
Gas Generator ◽  
Operating Range ◽  
Start Up ◽  
Partial Load

When designing a new plant, often it is necessary to make a simulation of the process in order to evaluate the dynamic behaviour of the whole system and the need of changes for its optimal performance. So dynamic models of the gas turbines used in the plant, either as mechanical drives or power generation, are needed. Actual gas turbines often incorporate variable geometry both in cold and hot sections. For example, the last generation of axial compressors are often equipped with variable geometry stator blades in order to achieve stable operation within the whole operating range, from start-up to full speed. As another example, power turbines sometimes have inlet guide vanes with a variable geometry in order to get a better efficiency at both partial load and speed, allowing the gas generator to run at the design speed. Disregarding to this, dynamic models which can be found in the actual literature deal with hot sections having a fixed geometry. This paper presents a dynamic model of two shaft heavy-duty gas turbines, with variable geometry in either cold and hot sections. It can be used to evaluate all the transient conditions such as start-up, shut-down and load variations in the normal operating range.

Application of a High Resolution Turbine Pyrometer to Heavy Duty Gas Turbines

2001 ◽  
Author(s):  
Stefan L. F. Frank ◽  
Tim O. Holt ◽  
Holger Eisenlohr ◽  
Dieter Raake
Keyword(s):  
Heat Transfer ◽  
High Resolution ◽  
Gas Turbine ◽  
Analytical Methods ◽  
Gas Turbines ◽  
Natural Frequencies ◽  
Load Test ◽  
Heavy Duty ◽  
Test Bed ◽  
Hot Gas

This paper describes the application of high resolution pyrometry for surface temperature measurements of the blading in heavy duty gas turbines. First of all, it is essential to know the actual loading, since the cylindrical pyrometer probes are traversed into the hot gas path. Therefore, analytical methods for the calculation of the heat transfer, equivalent stresses and natural frequencies of the probes are described here. The second part presents results of measurements from the latest model V84.3A 60Hz 180 MW gas turbine in the Berlin full load test bed. Emphasis is put on the effect of combustor radiation, limited resolution of the pyrometer and 3D presentations of the data.

Modified Fuel Control for a Large Heavy-Duty Combustion Turbine-Generator

1989 ◽  
Author(s):  
G. Quentin ◽  
G. Brawley ◽  
A. Loft ◽  
W. Perez-Daple
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Low Cycle Fatigue ◽  
Water Injection ◽  
Critical Element ◽  
Heavy Duty ◽  
Thermal Transients ◽  
Soft Start ◽  
Start Up ◽  
Acceleration And Deceleration

Thermal transients during start-up and shutdown of a heavy-duty gas turbine stress the hot gas path components and reduce their effective life due to low-cycle fatigue. Experience has shown that stress-related cracking and wear is more extensive on gas turbines in cyclic service that start and stop more frequently, than machines in baseload service that operate more continuously. The start-up schedules of most engines in peaking duty are generally designed to minimize the time to reach full load. Rapid loading is not a critical element for many gas turbine users, who would prefer alternate start-up schedules that could extend component life, by as much as a factor of three. It is the fuel controls that dictate thermal energy input to a combustion turbine during start-up and shutdown. Therefore, experiments performed on the rates of acceleration and deceleration led to modified fuel controls for a natural gas-fired combustion turbine (General Electric Model MS7001B), Unit 41 at the T. H. Wharton Plant of Houston Lighting & Power Co. The results may be generalized and applied to other gas turbines and control systems, using different fuels. Specific findings relate to quicker ignition, more gradual initial warm-up, a lower acceleration for a soft start, and lower deceleration during fired shutdown. Additionally, new minimum fuel settings enhanced running reliability during load-shedding operation with water injection for NOx control. The results are described and illustrated in detail to demonstrate the new start-up and shutdown sequence. Subsequently, one HL&P unit was permanently modified for check-out, and across-the-board updating of other units is planned.

Dynamical Analysis on Circumferential Rod Fastening Rotor System in Heavy-Duty Gas Turbine

2014 ◽  
Author(s):  
Huiguang Li ◽  
Lihua Yang ◽  
Weimin Wang ◽  
Shiquan Zhao ◽  
Xueyun Liu ◽  
...  
Keyword(s):  
Rough Surface ◽  
Gas Turbines ◽  
Natural Frequencies ◽  
Contact Stiffness ◽  
Rotor System ◽  
Dynamical Analysis ◽  
Heavy Duty ◽  
Normal Contact ◽  
Interface Contact ◽  
Rod Fastening Rotor

Circumferential rod fastening rotor system is widely used in heavy-duty gas turbines because of its advantages such as light weight, good cooling, easy assembly and so on. The force, torque or load between components in this type of rotor system must be transmitted depending on the contact interfaces. In this paper, the normal and tangential interface contact stiffness of rough surface are obtained according to the relationship between force and deformation of the finite element contact model which can reflect the surface topography. Then, the dynamic analysis method is presented and two models are built to analyze the dynamic performance of composite rod fastening rotor system. The effects of interface contact stiffness on the natural frequencies and unbalance responses of rotor system are studied. The results illustrate that the normal contact stiffness of rough surface linearly increase when the normal load rise, but the tangential contact stiffness decrease with the tangential pressure increasing. Furthermore, the contact stiffness has important effects on the natural frequencies and unbalance responses of rotor system. With the growth of contact stiffness, the natural frequencies increase, while the unbalance response amplitudes of rotor system decrease.

Diagnosis for Loose Blades in Gas Turbines Using Wavelet Analysis

2003 ◽  
Author(s):  
Meng Hee Lim ◽  
M. Salman Leong
Keyword(s):  
Steady State ◽  
Wavelet Analysis ◽  
Fourier Analysis ◽  
Gas Turbines ◽  
Natural Frequencies ◽  
Experimental Studies ◽  
Vibration Response ◽  
Operating Conditions ◽  
Operating Condition ◽  
Rotor Assembly

The application of wavelet analysis to diagnose loose blades condition in gas turbines is examined in this paper. Experimental studies were undertaken to simulate loose blades condition occurring in gas turbines in an attempt to understand vibration response associated with loose blades under different operating conditions. Results showed that loose blades were undetectable under steady state operating condition. During turbine coast down, loose blade could be detected based on impactic signals induced by the loose blades on the rotor and thus excited the natural frequencies of the rotor assembly. Results from the coast down condition showed that wavelet analysis was more sensitive and effective than Fourier analysis for loose blade diagnosis. The severity, the number, and the configuration of the loose blades could be potentially estimated based on the pattern of the coast down wavelet map.

Diagnosis for Loose Blades in Gas Turbines Using Wavelet Analysis

2005 ◽  
Vol 127 (2) ◽  
pp. 314-322 ◽  
Author(s):  
Meng Hee Lim ◽  
M. Salman Leong
Keyword(s):  
Steady State ◽  
Wavelet Analysis ◽  
Fourier Analysis ◽  
Gas Turbines ◽  
Natural Frequencies ◽  
Experimental Studies ◽  
Vibration Response ◽  
Operating Conditions ◽  
Operating Condition ◽  
Rotor Assembly

The application of wavelet analysis to diagnose loose blades condition in gas turbines is examined in this paper. Experimental studies were undertaken to simulate loose blades condition occurring in gas turbines in an attempt to understand vibration response associated with loose blades under different operating conditions. Results showed that loose blades were undetectable under steady state operating condition. During turbine coast down, a loose blade could be detected based on the impactic signals induced by the loose blades on the rotor and thus excited the natural frequencies of the rotor assembly. Results from the coast down condition showed that wavelet analysis was more sensitive and effective than Fourier analysis for loose blade diagnosis. The severity, the number, and the configuration of the loose blades could be potentially estimated based on the pattern of the coast down wavelet map.

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