bluuebunny/crossref_metadata_2025_split huggingface dataset:
Validation of ATI 20-25+Nb™ Alloy at 50,000 Hours in the Recuperator of a Gas Turbine Engine
Authors: Bender M. D. , Rakowski J. M. , Lipschutz M. D. 
Published: December 2013

A field test program to validate high temperature oxidation resistance of the ATI 20-25+Nb™ alloy in a Solar Turbines Incorporated Mercury™ 50 gas turbine engine has exceeded 50,000 operating hours. A primary goal of this program is to assess the effect of the actual recuperator operating environment on high temperature degradation of primary surface recuperator (PSR) materials. As PSRs are generally fabricated from thin foil materials, excessive degradation can cause perforation, leading to failure of components. To avoid such problems, PSRs are generally fabricated from nickel-base superalloys or highly-alloyed austenitic stainless steels. Previously, ATI 20-25+Nb (UNS S35140) stainless steel was developed and experimentally shown to have excellent creep resistance and good environmental resistance for a PSR application. This field test program evaluates the long-term performance of this alloy in situ in turbine exhaust and compares it with the more highly alloyed Ni-based 625 superalloy.
Sub-size air cell samples of alloy 625 and ATI 20-25+Nb alloy exposed for 50,000 hours (running time) in turbine exhaust were removed and tested for materials characterization. Analysis showed that both alloy 625 and ATI 20-25+Nb alloy exhibit excellent long-term resistance to environmental degradation, even after service exposure equivalent to over 5.5 years.
Design, Testing and Performance of the Recently Developed 37 MW Siemens SGT-750
Authors: Hellberg Anders , Andersson Thomas , Häggmark Anders 
Published: December 2013

The 37MW Siemens SGT-750 is a high-performance twin-shaft gas turbine with a free power turbine. It can be employed both for power generation and as a mechanical drive. This gas turbine attains a simple cycle efficiency level of 40% and excellent performance in cogeneration as well as in combined cycle.
Requirements from the oil & gas industry as well as industrial power generation have been heeded in the design. Since customer earnings are dependant upon turbine availability, uptime has been a major focus. Long service intervals, rapid gas generator exchange and easy access for borescope inspection all guarantee optimized availability. Maintenance work can be performed on site on the installed machine, alternatively the gas generator can be exchanged to minimize downtime. With this solution, maintenance downtime can be cut to a mere 17 days in 17 years. Furthermore, the hot-section blade temperatures can be monitored during operation as a “health check” to ensure availability.
The SGT-750 is a “low-emission engine” equipped with a dry low emission (DLE) combustion system minimizing NOx and CO emissions. The high efficiency leads to a reduction of greenhouse gases with the further possibility to reduce the relative CO2-emissions in cogeneration or combined cycle.
This paper will describe the development and testing of the SGT-750 gas turbine and the additional features which have been incorporated. A new development process has made it possible to increase uptime and serviceability; special attention has been brought to this aspect during the design phase, as will be highlighted in the paper.
Steam Turbine Exhaust Hood With Swirl Flow Separation Ducts
Authors: Mizumi Shunsuke , Ishibashi Kouji , Sawamura Yasuaki 
Published: December 2013

The efficiency of a steam turbine is significantly influenced by pressure recovery performance of its low-pressure exhaust hood; hence it is important to specify the cause of loss generation and to devise improved structures. The performance of the exhaust hood is greatly influenced by many structural factors such as the size of its outer casing, design of the diffuser parts and arrangement of internal supports.
Previously we optimized an exhaust hood using CFD. However, even for this exhaust hood, large and strong swirl flow was still observed and it seemed to be one of the main causes of the mixing loss. The vortex structure of the exhaust hood flow was carefully examined for this reason, and swirls with a strong vorticity were all found to originate from the upper part of the exhaust hood for all models calculated.
In the present study, we propose a new structure with special ducts capable of effectively decreasing the swirl strength. Then, we experimentally verify the effectiveness of the improved structure and confirm the possibility of further performance enhancement.
Development of Steam Turbines for State of the Art Combined Cycle Power Plants (CCPP)
Authors: Quinkertz Rainer , Hecker Simon 
Published: December 2013

In order to reduce CO2 emissions, reduce capital costs and increase the percentage of renewable energy in the electricity grid, common drivers of fossil power plant evolution continue to be efficiency, increased electricity output and operating flexibility.
For CCPP, the efficiency level has reached more than 60%. Besides new and updated gas turbine frames, an improved bottoming cycle also contributes to this achievement. Without increasing steam temperatures above 565°C, improving steam turbine inner efficiency and enhancing the cold end, the overall efficiency of >60% would not be feasible.
Extensive thermodynamic optimization is required to determine steam temperatures and condenser pressures. In addition, from a design standpoint, an optimum product strategy has to be developed. In order to minimize risks with future designs, both the practical and theoretical experiences from both ultra super critical applications at coal-fired steam power plants as well as from the CCPP steam turbine fleet have to be incorporated. For advanced technologies and components appropriate validation programs have to be defined.
This paper presents the approach being taking to develop steam turbines for CCPP with modern gas turbines and it also displays the operating results of the first unit.
Operational validation included the thermal behaviour of the high and intermediate pressure parts, a new last stage blade for the low pressure turbine and a patented start-up procedure. In particular, the paper focuses on the validation of three dimensional CFD calculations of the high and intermediate pressure turbine.
One Explanation for 2N Response due to Misalignment in Rotors Connected by Flexible Couplings
Authors: Avendano Raul D. , Childs Dara W. 
Published: December 2013

Misalignment in turbomachinery is commonly thought to produce two-times-running-speed (2N) response. The source of 2N vibration response was investigated, starting with the development of finite-element models for three flexible disc-pack couplings (4-bolt, 6-bolt, and 8-bolt couplings). Parallel and angular misalignments were analyzed. The resultant lateral stiffness terms had 1N, 2N, and 3N harmonic components versus the shaft rotation angle. The 4-bolt coupling had large 1N stiffness components under angular and parallel misalignment. The 6-bolt coupling had only a 1N reaction component under angular misalignment, while parallel misalignment showed a strong 2N reaction component, larger than either the 1N or 3N components. Under angular misalignment, the 8-bolt model produced large 1N reaction components. Under parallel misalignment, it produced 1N, 2N, and 3N components that were similar in magnitude. All the couplings behaved linearly in the range studied.
Some experts attribute observed 2N response to nonlinear bearing forces produced by bearings at high unit loads. Static tests for a 5-pad tilting-pad journal bearing with unit loads up to 34.5bars produced small 2N motion components that did not grow with increasing unit load.
A Jeffcott-rotor model with shaft stiffness orthotropy and a fixed-direction side load predicts that 2N response depends on three related factors: (1) the degree of orthotropy (the 1N stiffness variation magnitude), (2) the magnitude of the side load, and (3) the relative ratio of running speed to rotor 1st natural frequency, (ω/ωn). The 2N response magnitude is largest when ω is close to ωn/2. The side load is required to create 2N response due to shaft stiffness orthotropy. Misaligned couplings create precisely the same (very old) physical model as a two-pole turbogenerator rotor with a gravity side load (gravity critical speed).
The response of a 2-rotor/coupling system with parallel and angular misalignment was simulated using a time-transient code. When the frequency ratio was 0.5, the system response with the 4-bolt and 6-bolt coupling had a synchronous 1N component as well as a significant 2N component. Parallel misalignment at a coupling produces stiffness orthotropy and a fixed-direction side load. For ranges of running speed near ωn/2, these two elements can combine to produce 2N response.
Design Study of Dovetail Geometries of Turbine Blades Using Abaqus and Isight
Authors: Hahn Youngwon , Cofer John I. 
Published: December 2013

Blades in gas and steam turbines continually face more challenging requirements for high reliability and efficiency. In order to meet these challenges in an increasingly competitive marketplace, blade design engineers are always looking for more efficient ways to design the blades in the shortest possible time and at the lowest possible cost while meeting multiple design objectives. In this paper, several design studies are performed using Abaqus and Isight to optimize the minimum contact pressure and stress around the dovetail of a typical turbine blade in order to achieved desired goals for stress levels.
First, nine design parameters describing the dimensions of the dovetail are set up in a Python script which can be executed in Abaqus/CAE. The Python script generates the entire finite element model including boundary and loading conditions in Abaqus/CAE. A nonlinear static analysis considering centrifugal loading is performed in this work. After setting up the workflow using the Python script and Abaqus/CAE, Isight is used to automate the process to achieve the optimized dimensions of the dovetail.
The optimization is performed in two steps. First, a surrogate model using the Optimal Latin Hypercube approximation method is created using tools in Isight. In this step, the surrogate model is used to determine the optimum values of the design variables, as well as the sensitivity of the design to the selected design variables. It also can be observed that the design is especially sensitive to five of the design variables. In the second step of the optimization, the five design variables to which the design is most sensitive are selected for further optimization by setting the other design variables to the optimized values obtained in the first step of the optimization. In this second step, several different optimization methods supported in Isight are used, including the NSGA-II non-dominated sorting genetic algorithm, Downhill Simplex, and an evolutionary optimization algorithm. Results from these methods are compared with those obtained using other common optimization methods in Isight.
Performance Study and Instability Analysis of Steam Turbine Control Valve
Authors: Engeda Abraham 
Published: December 2013

Industrial steam turbines represent one of the largest fractions of prime movers. Regardless of the steam-turbine application being considered, speed and/or load control will be required. Speed control is the primary control loop for all turbine applications, industrial as well as utility. The inlet of industrial steam turbine is usually controlled by a single valve, or a series of valves (multi-valve assembly) working in concert. As a turbine governing valve, the venturi valve, has been widely used in steam turbines to regulate inlet flow in the last 40 years. But as turbine output power become larger, a number of valve failure incidences started to be reported and improving the valve designs became a high priority. But despite numerous investigations to eliminate valve failure, the attempts were not fully successful due to the complicated nature of the fluid-structure interaction mechanisms, and the basic mechanism causing valve vibration and failure is still far from being fully understood. Steam control valves are required to operate under wide ranges of valve openings and pressure ratios.
As a continuation of previous valve designs, a newly designed valve with two different seat configurations has been investigated experimentally and studied. This paper reports the results of one of the newly designed valves with a short seat configuration. This paper presents detailed experimental investigations to clarify the mechanisms of valve instability caused by unsteady flows around the valve. A result of the asymmetric unstable flow, noise and vibration characteristics of the valve together with an overall performance assessment of the valve is presented.
MS5002C and D “Power Crystal™ Kit” Heavy Duty Gas Turbine Development and Operating Experience
Authors: Del Turco Paolo , D’Ercole Michele , Fouad Ahmed Ossama , Carta Riccardo , Russo Alessandro , Lombardi Gaetano , Calicchio Vincenzo , Gori Stefano 
Published: December 2013

Given the constant increase in world energy demand, gas turbine operators are continuously looking for turbo-machinery improvements, both in terms of increased power and extended maintenance intervals, limiting, as much as possible, the downtime for upgrading.
In 2006, GE Oil & Gas engineers launched the Power Crystal™ development program to enhance the output power or extend the maintenance interval of the MS5002C and D heavy duty gas turbines.
This effort resulted in an upgrade kit potentially to be installed during a standard major inspection, which include a single crystal material 1st stage high pressure turbine blade and additional improvements, such as new coatings for combustor hardware and improved cooling of the 1st stage high pressure turbine nozzle and 1st stage high pressure turbine wheel.
The upgrade kit was validated through an extensive test campaign, which included test-rig component tests in advance of the First Engine to Test (FETT).
All critical-to-quality parameters of the gas turbine were investigated, such as turbine gas path component temperatures and stresses, performance and operability.
This paper describes the background for the upgrade, discusses the new kit features, how the test program was built and conducted, and reports the experience accumulated on the gas turbine during the initial field operation.
Performance Study of an Air-Oil Pump and Separator Solution
Authors: Steimes Johan , Gruselle François , Hendrick Patrick 
Published: December 2013

Many applications need to extract a certain phase from a multiphase flow like in oil extraction, flow in nuclear power plants, aircraft lubrication systems, etc. The Aero-Thermo-Mechanics (ATM) Department of Universiteé Libre de Bruxelles (ULB) is developing an original system to extract the gas from a liquid-gas flow together with increasing the pressure of the liquid phase. This system will help to reduce the complexity and the oil consumption of aeroengine lubrication systems.
This paper will summarise the results of a first air/oil prototype. It will also present the guidelines learned from this prototype and used to design a second version of the integrated pump and separator. A newly developed oil consumption measurement system will also be presented. Based on previous results, on litterature review and on an in-house theoretical model, the paper will explain theoretically how the separation efficiency is affected by the particle distribution at the inlet of the prototype, and by the key parameters identified in different studies. Finally the conclusions will present the lessons learned through the design and tests of these two prototypes and the future work will be presented.
Component Testing and Prototype Commissioning of MAN’s New Gas Turbine in the 6 MW-Class
Authors: Wiedermann Alexander , Orth Ulrich , Aschenbruck Emil , Reiss Frank , Krüger Dietmar , Wiers Sven-Hendrik 
Published: December 2013

MAN Diesel & Turbo has developed a new gas turbine in the 6 MW-class for both mechanical drive and power generation applications. The lay-out of the Gas Turbine has been driven by opportunities in current and future markets and the positioning of the competition, and this has determined the characteristics and technical parameters which have been optimized in the 6 MW design.
The design makes use of extremely high precision engineering so that the assembly of sub components to modules is a smooth flowing process and can guarantee both the high standards in quality and performance which MAN Diesel & Turbo is aiming for. Individual components have been tested and thoroughly validated. These tests include in particular the compressor of the gas turbine and the combustion chamber.
The commissioning of the gas turbine prototype engine had been prepared with a numerous number of measuring probes and carried out at the Oberhausen plant gas turbine test field. Results of component and the gas turbine prototype tests will be presented and discussed.
Dynamic Response Analysis of Rotor System With Uncertain Parameters via Interval Analysis Method
Authors: Hong Jie , Wang Jun , Chen Meng , Ma Yanhong 
Published: December 2013

The support stiffness and connecting structure stiffness change with different assembly conditions and operating conditions. The phase and amount of rotor unbalance in different operating cycle changes due to wear of blade tip and connecting structures in different working cycles. These parameters which have significant effect on rotordynamics are “uncertain but bounded”, in another word, the distributions of the parameters are unknown, but the intervals of uncertain parameters are always got easier.
An interval analysis method, which solves the dynamic response with these uncertain parameters, has presented. Based on interval mathematics and modal superposition method, interval analysis method simplifies the uncertain parameters to interval vectors so that it can get the intervals within which the dynamic response varies when less information of structure is known. The interval analysis method is efficient under the condition that probability approach cannot work because of small samples and sparse statistics characteristics. The formulation of rotor dynamic response using interval modal superposition analysis method is formulated. A numerical example of comparison between interval analysis method and Monte Carlo method is given, and the results illustrate the interval analysis method.
A Study of Nonlinear Vibrations in a Frictionally-Damped Turbine Bladed Disc With Comprehensive Modelling of Aerodynamic Effects
Authors: Petrov E. P. , Zachariadis Z.-I. , Beretta A. , Elliott R. 
Published: December 2013

A new effective method for comprehensive modelling of gas flow effects on vibration of nonlinear vibration of bladed discs has been developed for a case when effect of the gas flow on the mode shapes is significant.
The method separates completely the structural dynamics calculations from the significantly more computationally expensive computational fluid dynamics (CFD) calculations while provides the high accuracy of modelling for aerodynamic effects.
A comprehensive analysis of the forced response using the new method has been performed for a realistic turbine bladed disc with root-disc joints, tip and underplatform dampers. The full chain of aerodynamic and structural calculations are performed: (i) determination of boundary conditions for CFD; (ii) CFD analysis; (iii) calculation of the aerodynamic characteristics required by the new method; (iv) nonlinear forced response analysis using the MAIM. The efficiency of the friction damping devices has been studied and compared for several resonance frequencies and engine orders. Advantages of the method for aerodynamic effect modelling have been demonstrated.
Experimental Testing of a Magnetically Levitated Rotor With a Neural Network Controller
Authors: Veloz Alejandro , Romero Quintini Juan C. , Parada Mónica , Diaz Sergio E. 
Published: December 2013

Magnetic bearings represent a solution for high rotating speeds and sterile environments where lubrication fluids could contaminate. They can also be used in systems where maintenance is difficult or inaccessible, because they don’t require auxiliary lubrication systems and don’t suffer mechanic wear as they work with no contact between rotor and bearing stator. An important part of magnetic bearings is the controller; which is needed to stabilize the system. This controller is generally a PID in which tuning and/or filters design can be complicated for not well known systems. This work presents results of the development of a neural network controller, which is potentially easier to implement, to control the position of a magnetically suspended rotor.
The proposed controller is based in the identification of the system inverse model. This is achieved first by implementing a simple PID capable of levitating the rotor, and then some excitations are applied to the rotor in order to acquire data of the position of the rotor and current in the actuators. Current and position data is used to train the artificial neural network for the controller.
The controller was implemented in a numerical model and also in an experimental system with a rotor of 1.06kg and 300mm in length. The implementation of SISO, MISO and MIMO neural controllers (both with offline and online training) and a conventional PID with neural network compensation are compared.
Structures and architectures of networks are shown. Vibration responses to: a constant force; a controlled impact and a constant acceleration ramp between 0 and 12500rpm are compared. Results in both, numeric model and experimental system, show that neural network controllers are capable of hovering the rotor and control vibrations. Peak-Peak amplitudes vs. rpm plots are similar to a conventional PID. In most cases, the neural network controllers show amplitudes slightly lowers on low frequencies and slightly higher on higher frequencies, except the conventional PID with neural network compensation case, were the system responses as with higher damping. Finally, a discussion is made about future steps in research to improve implementation of a neural controller that is potentially simpler and faster in terms of tuning and with a comparable performance to a conventional magnetic bearing PID controller.
Modelling of Flange Joints for the Nonlinear Dynamic Analysis of Gas Turbine Engine Casings
Authors: Schwingshackl C. W. , Petrov E. P. 
Published: December 2013

The finite element analysis of individual components of aircraft engine casings provides high accuracy and a good agreement with the measured response data. However, when these components are assembled, the accuracy of such predictions can significantly deteriorate since models describing stiffness and friction properties of joints are linearised.
A full nonlinear analysis of the casing flanges is required to fully include the influence of the bolted joints, model the flexibility in the contact interface, and consider the nonlinear behaviour of the contact due to partial slip and separation. In this paper different nonlinear models of casings are investigated with an available nonlinear analysis tool; A parametric study of the contact interface meshes is conducted to identify a satisfying analysis approach. The dynamic flange behaviour is analysed in detail, including effects of the bolt and normal load distribution. A comparison of the introduced nonlinear modelling with more traditional rigid or linear-elastic flange joint models is carried out to evaluate the effect of the nonlinear approach.
The study demonstrates the nonlinear nature of a casing flange joint and highlights the need to include them in the analysis. The detailed modelling of the contact interaction of joints, gives an insight in the nonlinear contact behaviour of flanges of aircraft engine casings, and the predictive capabilities for the nonlinear analysis of gas turbine engines.