bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Turbine Operation Offshore: On-Line Compressor Wash Operational Experience
Authors: Madsen Stian , Bakken Lars E. 
Published: September 2014

On-line compressor wash for six GE LM2500PE engines at a Statoil North Sea offshore field is analyzed. Three engines are generator drivers whilst three engines are compressor drivers. Two of the compressor drive engines are running at peak load (T5.4 control), hence production rate is limited by the available power from these engines. All the six engines analyzed run continuously without redundancy, hence gas turbine uptime is critical for the field’s production and economy. The performance and operational experience with online wash at different water-to-air ratios and engine loads, as well as economy potentials related to successful on-line washing are given.
This work is based on long-term operation with on-line washing, where operational data is collected and performance analyzed, over a 4–5 year period. All engines are operated with four month intervals between maintenance stops, where off-line crank-wash is performed as well as other necessary maintenance and repairs. On-line wash is performed daily between the maintenance stops at full load (i.e. normal operating load for the subject engine). To keep the engine as clean as possible and reduce degradation between maintenance stops, both an effective on-line water wash system as well as effective air intake filter system, are critical factors. The overall target is to maintain high engine performance, and extend the interval between maintenance stops through effective on-line washing.
It is of vital importance to understand the gas turbine performance deterioration. The trending of its deviation from the engine baseline facilitates load-independent monitoring of the gas turbine’s condition. Engine response to water injection at different loads and water-to-air ratios, as well as engine response to compressor deterioration is documented and analyzed.
Instrument resolution and repeatability are key factors required in order to obtain reliable performance analysis results. Offshore instrumentation on older installations is often limited to the necessary instruments for machine control/protection, and additional instruments for effective performance monitoring and analysis are often missing or, if installed, have less accuracy. As a result of these analyses, a set of monitoring parameters is proposed for effective diagnosis of compressor degradation. Avenues for further research and development are proposed in order to further increase the understanding of the deterioration mechanisms and of the gas turbine performance and response.
Quantitative CFD Analyses of Particle Deposition on a Transonic Axial Compressor Blade: Part I — Particle Zones Impact
Authors: Suman Alessio , Kurz Rainer , Aldi Nicola , Morini Mirko , Brun Klaus , Pinelli Michele , Spina Pier Ruggero 
Published: September 2014

Solid particle ingestion is one of the principal degradation mechanisms in the turbine and compressor sections of gas turbines. In particular, in industrial applications, the micro-particles not captured by the air filtration system cause fouling and, consequently, a performance drop of the compressor. This paper presents three-dimensional numerical simulations of the micro-particle ingestion (0–2 μm) on an axial compressor rotor carried out by means of a commercial computational fluid dynamic code. Particles of this size can follow the main air flow with relatively little slip, while being impacted by flow turbulence. It is of great interest to the industry to determine which areas of the compressor airfoils are impacted by these small particles.
Particle trajectory simulations use a stochastic Lagrangian tracking method that solves the equations of motion separate from the continuous phase. Then, the NASA Rotor 37 is considered as a case study for the numerical investigation. The compressor rotor numerical model and the discrete phase treatment have been validated against the experimental and numerical data available in literature. The number of particles, sizes, and concentrations are specified in order to perform a quantitative analysis of the particle impact on the blade surface.
The results show that micro-particles tend to follow the flow by impacting at full span with an higher impact concentration on the pressure side. The suction side is affected only by the impact of the smaller particles (up to 1 μm). Particular fluid-dynamic phenomena such as separation, stagnation point and tip leakage vortex strongly influence the impact location of the particles.
Development and Experimental Evaluation of Endothermic Fuel for Better Combustion and Life of Combustor: In Realistic Test Setup
Authors: Ganapuram Venu , Jangam Srinivas , Pulumathi Manjunath , Iyengar Venkat , Thippareddy Aruna Singanahalli , Rajaram Kannan 
Published: September 2014

The concept of endothermic fuels is not a strange thing to the aeronautical community. Research is going on, globally, to achieve these kinds of fuels experimentally; but restricted to laboratory scale test setup. This is because of the stringent and controlled method of cracking the fuel thermally as well as catalytically. In this research work we have followed a systematic approach, i.e, developed a laboratory scale reactor for the preliminary feasibility studies and a realistic experimental set up, for the development and analysis of the cracked fuel by simulating the conditions of combustor walls. Developing this technology indigenously involves many steps, namely identification of the suitable catalysts, developing the technology of preparation of catalytically active coatings and then the design and fabrication of the catalytic cracking core. Finally the catalytic cracking core has to be integrated to the test combustor with the experimental setup. To carry out the catalytic cracking reaction, a high pressure and high temperature catalytic reactor was designed and developed. The reactor can heat kerosene up to 725 K and maintain pressures up to 10 bar. The catalytic coatings were prepared with ZSM-5 and molecular sieves (20:80); coated on aluminum cylinders. A temperature drop of 114 K was obtained when kerosene fuel was passed through the catalytic system. This clearly shows the cooling effect by the endothermic fuel. A mixed bed catalytic system (Molecular sieves, Reformax-100 and ZSM-5) was also developed for the in-situ generation of Hydrogen gas along with the catalytic cracking process. The presence of Hydrogen gas in the cracked fuel is confirmed by gas chromatographic (GC) Retention time Vs Voltage investigation.
The experimentation in test rig was carried out in two modes, one is for thermal cracking (absence of catalyst) of kerosene fuel and the other one is catalytic cracking. In both the cases, the combustor duct is heated by hot air to 1200 K. Skin temperatures were measured to study the cooling effect of the endothermic fuel and the results are reported in this paper. It is noticed that the chemical composition of the kerosene fuel has been changed and fragmented into lighter chains. It is evident in the Gas Chromatography results that the catalytically cracked kerosene samples (gaseous and liquid samples) are having 30% higher of lighter chains (Ethane, Propane and Butane) of chemical compounds than thermally cracked kerosene samples. As expected, the fuel has got cracked thermally and catalytically while cooling the wall of the duct (simulating the actual flight conditions to realize the practical feasibility of generating endothermic fuels rather than restricting it to laboratory scale experiments).
On Predicting the Phenomenon of Surface Flow Convergence in Wind Farms
Authors: Selvaraj Suganthi , Sharma Anupam 
Published: September 2014

A systematic analysis of a single-rotor horizontal axis wind turbine aerodynamics is performed to obtain a realistic potential maximum efficiency. It is noted that by including the effects of swirl, viscosity and finite number of blades, the maximum aerodynamic efficiency of a HAWT is within a few percentage points of the efficiency of commercially-available turbines. The need for investigating windfarm (as a unit) aerodynamics is thus highlighted.
An actuator disk model is developed and implemented in the OpenFOAM software suite. The model is validated against 1-D momentum theory, blade element momentum theory, as well as against experimental data. The validated actuator disk model is then used to investigate an interesting microscale meteorological phenomenon called “flow convergence” caused by an array of wind turbines. This phenomenon is believed to be caused by the drop of pressure in wind farms. Wind farm numerical simulations are conducted with various approximations to investigate and explain the flow convergence phenomenon.
Aerodynamic Data for Two Variants of Root Turbine Blade Sections for a 54″ Turbine Rotor Blade
Authors: Šimurda David , Luxa Martin , Šafařík Pavel , Synáč Jaroslav , Rudas Bartoloměj 
Published: September 2014

Aerodynamic investigations were performed on planar blade cascades representing two alternative root sections of rotor blades 54″ in length with straight fir-tree root. Each of the variants was designed for different number of blades in the rotor. This paper presents the results of measurements showing the dependency of the kinetic energy loss coefficient and the exit flow angle on the exit isoentropic Mach number and the angle of incidence. Images of the flow fields are also presented. The experimental data is analyzed to assess and document the difference between the two root section designs.
Results show that requirement of straight fir tree root leading to high design incidence angles significantly limit operation range. Also in case of root sections with high exit Mach numbers a limit load conditions are an issue. In order to utilize available pressure drop blade cascade throat/pitch ratios should be kept as high as possible which favorites variant with lower number of blades and higher outlet metal angle (relative to axial direction).
The Effect of Endwall Manufacturing Variations on Turbine Performance
Authors: Grewe Robert P. , Miller Robert J. , Hodson Howard P. 
Published: September 2014

Turbine blades and vanes of modern aero-engines are commonly manufactured by casting. The casting process often introduces slight geometry variations. In the endwall region this leads to inter-platform steps, gaps and leakage flows. This paper determines the underlying loss mechanisms associated with each of these geometric features and guides designers in minimizing their impact on efficiency.
The paper shows that the presence of an inter-platform step causes a pair of vortical structures to be superimposed onto the blade existing secondary flow structure. These are shown to always increase loss. When manufacture variations are considered the optimal design intent blade is shown to be one where the suction side endwall is lower than the pressure side endwall.
The paper shows that when leakage mass flow is introduced the presence of a step can either raise or reduce loss. A correlation which gives the optimal step height for a set leakage mass flow is presented. In the final part of the paper measured engine vane geometries are used to determine the impact of endwall geometry variation on turbine stage efficiency.
A Laser-Optical Sensor System for Simultaneous Tip Clearance and Vibration Monitoring of Compressor Rotor Blades
Authors: Neumann M. , Dreier F. , Günther P. , Fischer A. , Czarske J. , Holzinger F. , Schiffer H.-P. 
Published: September 2014

In order to improve the efficiency and increase the life-time of compressors and turbines, online monitoring of operating parameters is an essential tool. One aim is to predict critical events like stall or flutter by observing blade vibrations and deformations. Due to superior material properties ceramic, carbon-fiber and glass-fiber reinforced composite blades become more and more popular. Hence, conventional measurement systems like capacitive probes are not able to deliver the necessary precision or, in the worst case, are not able to measure at all. Therefore, we developed a fiber-coupled, laser-optical sensor, named laser Doppler distance sensor (LDDS), which overcomes this drawback. The sensor is able to resolve the circumferential blade tip velocity as well as the radial expansion of each blade. Moreover, conventional blade tip timing measurements are possible as well.
Our aim is to provide a universal stall prediction and monitoring sensor system that is applicable to all types of blades.
A Simplified Method for Determining Gas Turbine Performance Parameters Based Upon Available Catalogue Data
Authors: Ranasinghe Chamila , Noor Hina , Jayasuriya Jeevan 
Published: September 2014

Overall theoretical performance analysis of gas turbines can be conducted by applying design parameters into several thermodynamic theories and equations. However, limited availability of the design parameters will not provide sufficient room for a detailed analysis. Gas turbine manufacturers publish only a limited amount of design/performance data, while important parameters remained hidden and the available information is not sufficiently enough for obtaining a complete gas turbine performance dataset. Five main parameters commonly provided by a gas turbine manufacturer’s catalogues; pressure ratio of the compressor, exhaust mass flow rate, exhaust temperature of flue gas, overall efficiency, and electrical output. A theoretical model developed based on Mathcad software as documented in literature is used to reveal other hidden gas turbine parameters. A similar theoretical model using another solver was developed to obtain a complete dataset by using the available catalogue data with additional assumptions, which correspond to the commercial state of the art.
The engineering equation solver (EES) software has been used as a platform to rebuild the theoretical model. As the main development, a graphical user interphase (GUI) has been introduced to the new program with the aim to make it more user friendly. Furthermore on top of obtaining the hidden thermodynamic parameters for the gas turbine, performing flue gas analysis and an exergy analysis has now become possible through this program. The developed EES program is expected to be run in the learning laboratory at the Division of Heat and Power Technology, Department of Energy Technology, Royal Institute of Technology (KTH), Stockholm and finally it is going to be incorporated into CompEdu Learning Platform of the same division.
Heat Transfer Measurements of Oblong Pins
Authors: Kirsch Kathryn L. , Thole Karen A. 
Published: September 2014

Pin fin arrays are employed as an effective means for heat transfer enhancement in the internal passages of a gas turbine blade, specifically in the blade’s trailing edge. Various shapes of the pin itself have been used in such arrays.
In this study, oblong pin fins are investigated whereby their long axis is perpendicular to the flow direction. Heat transfer measurements were taken at the pin mid-span with unheated endwalls to isolate the pin heat transfer. Results show important differences in the heat transfer patterns between a pin in the first row and a pin in the third row. In the third row, wider spanwise spacing allows for two peaks in heat transfer over the pin surface. Additionally, closer streamwise spacing leads to consistently higher heat transfer for the same spanwise spacing. Due to the blunt orientation of the pins, the peak in heat transfer occurs off the stagnation point.
Investigation on the Effect of Dimension on the Compression Mechanics of Metal Rubber
Authors: Ma Yanhong , Gao Di , Hong Jie 
Published: September 2014

Metal Rubber (MR) is an attractive porous material used in vibration absorbers within extremely harsh environments. It is in general acknowledged that the sliding friction existing at the contact points between individual wires dominates the damping performance of MR products, but few people concern the effects of the dimension of metal rubber on the mechanical characteristics including modulus and damping. In order to discover the influencing laws of initial height and initial bearing area of metal rubber on its properties, three batches of MR specimens were fabricated and a series of experiments were carried out.
This study describes the manufacturing and testing of metal rubber (MR) samples made of stainless steel, and subjected to compression-compression loading in quasi-static regime. Three batches of MRs with different dimensions and similar relative density have been fabricated, and their mechanical properties (tangent modulus and loss factor) have been investigated and compared at different strains and under cyclic loading. The experiments show the significant effect of the MRs’ initial height and bearing area over the global mechanical compression properties, with the loss factor decreasing in samples with higher height and smaller bearing area, and the tangent modulus increasing with higher height. The phenomenon was explained by the MR spiral wire model, which employed MR’s boundary effect and different contact types of interaction. When a metal rubber sample is manufactured, the final process is to be formed in a specially designed mold by applying a compressive force, the MR is then shaped in the mold, and when the compressive force gradually decreases, the MR will rebound along molding direction, but restricted by the mold along the non-molding directions. This manufacturing process causes the different properties between the boundary and the inner part of the metal rubber solid, and the different contact types between individual wires contribute to the different properties. In this work, MR samples with different height were tested and compared, the results were consistent with the analysis that the boundary part along molding direction has more slip interaction, and samples with different bearing area were tested and compared to investigate the boundary effect along non-molding directions, the results were consistent with the analysis that this boundary part has more stick interaction. The results show that the dimension effect should be considered in the design of vibration dampers made with MR material, and we can control the mechanical properties of MR component by changing the size and combination form.
Experimental Investigation of a Fuel Flexible Generic Gas Turbine Combustor With External Flue Gas Recirculation
Authors: Fischer Stefan , Kluß David , Joos Franz 
Published: September 2014

Flue gas recirculation in combined cycle power plants using hydrocarbon fuels is a promising technology for increasing the efficiency of the post combustion carbon capture and storage process. However, the operation with flue gas recirculation significantly changes the combustion behavior within the gas turbine.
In this paper the effects of external flue gas recirculation on the combustion behavior of a generic gas turbine combustor was experimentally investigated. While prior studies have been performed with natural gas, the focus of this paper lies on the investigation of the combustion behavior of alternative fuel gases at atmospheric conditions, namely typical biogas mixtures and syngas. The flue gas recirculation ratio and the fuel mass flow were varied to establish the operating region of stable flammability.
In addition to the experimental investigations, a numerical study of the combustive reactivity under flue gas recirculation conditions was performed.
Finally, a prediction of blowout limits was performed using a perfectly stirred reactor approach and the experimental natural gas lean extinction data as a reference. The extinction limits under normal (non-vitiated) and flue gas recirculation conditions can be predicted well for all the fuels investigated.
Design and Characterization of an Inlet Duct for Mass Flow Measurement in a Micro Gas Turbine Test Rig
Authors: Buratto C. , Carandina A. , Morini M. , Pavan C. , Pinelli M. , Spina P. R. 
Published: September 2014

In this paper, a test rig for experimentation on a micro gas turbine is presented. The test rig consists of a micro gas turbine Solar T-62T-32, which, coupled with a 50 kVA alternator, can supply electrical energy to a calibrated resistive load bank. Particular attention is paid to the design of the inlet duct for the mass flow rate measurement. The basic issue was to create the intake duct for a micro gas turbine (MGT) test rig, in order to provide precise data about the mass flow rate and the thermodynamic air characteristics in the MGT inlet section. The inlet duct is also designed in order to allow future tests on inlet cooling technologies.
The MGT is incorporated in a chassis for noise reduction, the dimensions of which are 540 mm (height), 570 mm (width) and 940 mm (length). These small dimensions lead to problems with the insertion of the duct. Moreover, the intake of the compressor is not axial but radial, and this means that a volute must be foreseen to convey the flux into the MGT.
Several shapes of volute are analyzed in this paper, considering the effects on the pressure loss and the induction of turbulence. The challenge was to develop a fluid-dynamically efficient duct with the hindrance of a very small available space between the compressor casing, the gearbox and the fuel pipes inside the narrow noise-reduction chassis.
The mass flow rate will be computed by means of the differential static pressure between the upstream and the downstream section of a Venturi tube. The choice of a Venturi was due to the fact that it produces a pressure loss lower than any other device, such as orifice plates or other nozzle shapes. Furthermore, the expected mass flow rate would lead to high fluid speeds and, as a consequence, the diameter ratio between the duct and the throat of the Venturi was chosen to be as high as possible.
Uncertainty Quantification, Rare Events and Mission Optimization: Stochastic Variations of Metal Temperature During a Transient
Authors: Montomoli F. , Amirante D. , Hills N. , Shahpar S. , Massini M. 
Published: September 2014

Gas turbines are designed to follow specific missions and the metal temperature is usually predicted with deterministic methods. However, in real life the mission is subjected to strong variations which can affect the thermal response of the components. This paper presents a stochastic analysis of the metal temperature variations during a gas turbine transient.
A Monte Carlo Method (MCM) with Meta Model is used to evaluate the probability distribution of the stator disk temperature. The MCM is applied to a series of CFD simulations of a stator well, whose geometry is modified according to the deformations predicted during the engine cycle by a coupled thermo-mechanical analysis of the metal components. It is shown that even considering a narrow band for the stochastic output, +/− σ, the transient thermal gradients can be up to two orders of magnitude greater than those obtained with a standard deterministic analysis. Moreover, a small variation in the tail of the input probability density function, a rare event, can have serious consequences on the uncertainty level of the temperature.
Rare events although inevitable they are not usually considered during the design phase. In this paper it is shown for the first time that is possible to mitigate their effect, minimizing the maximum standard deviation induced by the tail of the input PDF. The mission optimization reduces the maximum standard deviation by 15% and the mean standard deviation of about 12%. The maximum thermal gradients are also reduced by 10%, although this was not the parameter used as the goal in the optimisation study.