bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Turbine Combined Cycle With CO2-Capture Using Auto-Thermal Reforming of Natural Gas
Authors: Andersen Thormod , Kvamsdal Hanne M. , Bolland Olav 
Published: August 2014

A concept for capturing and sequestering CO2 from a natural gas fired combined cycle power plant is presented. The present approach is to decarbonise the fuel prior to combustion by reforming natural gas, producing a hydrogen-rich fuel. The reforming process consists of an air-blown pressurised auto-thermal reformer that produces a gas containing H2, CO and a small fraction of CH4 as combustible components. The gas is then led through a water gas shift reactor, where the equilibrium of CO and H2O is shifted towards CO2 and H2. The CO2 is then captured from the resulting gas by chemical absorption. The gas turbine of this system is then fed with a fuel gas containing approximately 50% H2. In order to achieve acceptable level of fuel-to-electricity conversion efficiency, this kind of process is attractive because of the possibility of process integration between the combined cycle and the reforming process.
A comparison is made between a “standard” combined cycle and the current process with CO2-removal. This study also comprise an investigation of using a lower pressure level in the reforming section than in the gas turbine combustor and the impact of reduced steam/carbon ratio in the main reformer. The impact on gas turbine operation because of massive air bleed and the use of a hydrogen rich fuel is discussed.
Aero-Thermodynamic Simulation of a Double-Shaft Industrial Evaporative Gas Turbine
Authors: Camporeale S. M. , Fortunato B. 
Published: August 2014

A modeling study has been carried out in order to determine the behavior of evaporative industrial gas turbines power plants at part-load and for varying ambient temperature.
On-design and off-design performance have been analyzed by means of a computational program developed for the analysis of advanced cycles.
In order to verify the mathematical model and to evaluate the characteristics of up-to-date gas turbine technology, an industrial engine, presently available on the market, has been simulated. A double-shaft gas turbine for power generation has been considered. On-design performance and ratings vs. ambient temperature have been evaluated, with good accordance.
It is assumed that, in order to realize a Recuperated Water Injected (RWI) cycle, the industrial gas turbine could be modified, maintaining substantially unchanged the compression system and modifying the turbine blades.
The thermodynamic analysis of the cycle has been carried out in order to determine efficiency and power output as a function of the amount of water addition.
The RWI cycle gas turbine has been designed and the characteristic maps of the two new turbines have been evaluated.
The regulation is performed by means of the simultaneous manipulation of fuel flow rate, water rate, and position of the free turbine nozzle guide vanes (NGV). The regulation criteria, the interaction among the input variables, the safety of the operations (max. turbine inlet temperature, surge limits) and the optimization of the part-load efficiency, are examined and discussed.
Ratings as a function of the ambient temperature are examined. The possibility to manipulate the water rate and the position of the NGV in order to provide high efficiency and power output, even on hot days, has been examined.
The paper shows that maintaining constant the temperature at the power turbine exit, ratings decrease of 17% in power and 5% in efficiency.
Conceptual Design for Medium Size Combined Cycle Plants Improved by Recent Research and Innovation
Authors: Jericha H. , Neumayer F. 
Published: August 2014

A conceptual design study for a 120 MW combined cycle plant is presented here. Values of 60% thermal efficiency are at present the realm of very large gas turbines of most advanced design with power outputs of 300 to 500 MW. For industry and district heating plants it would be of most economic value to achieve similar thermal efficiencies in medium size gas turbines and combined cycle plants as they are being installed in Central European cogeneration and district heating plants.
The authors propose by concerted application of recent research results to achieve this goal for medium size combined cycle plants. Design measures incorporated are transonic turbine stages, an innovative cooling system and a 600 degree reheat steam turbine.
Manufacturers’ Role in the Power Industry
Authors: Mukherjee Dilip K. 
Published: August 2014

This paper discusses the transformation which the power industry is presently undergoing and its impact on manufacturers’ business. The key success factors for a Manufacturer in today’s market are:
• Global market coverage with local customer services
• Broad portfolio of products and solutions
• Economy of scale and cost efficiency
• Substantial R&D resources for the technology race
Significant challenges exist for the manufacturers to fulfil the requirements, especially those relating to the proper organisational set-up, the right product and the required R&D program.
Influence of Surface Roughness on Heat Transfer and Effectiveness for a Fully Film Cooled Nozzle Guide Vane Measured by Wide Band Liquid Crystals and Direct Heat Flux Gauges
Authors: Guo S. M. , Lai C. C. , Jones T. V. , Oldfield M. L. G. , Lock G. D. , Rawlinson A. J. 
Published: August 2014

The influence of surface roughness on heat transfer coefficient and cooling effectiveness for a fully film cooled 3D nozzle guide vane (NGV) has been measured in a transonic annular cascade using wide band liquid crystal and direct heat flux gauges (DHFGs). The liquid crystal methods were used for rough surface measurements and the DHFGs were used for the smooth surfaces. The measurements have been made at engine representative Mach and Reynolds numbers and inlet freestream turbulence intensity. The aerodynamic and thermodynamic characteristics of the coolant flow have been modelled to represent engine conditions by using a heavy “foreign gas” (30.2% SF6 and 69.8% Ar by weight). Two cooling geometries (cylindrical and fan-shaped holes) have been tested. The strategies of obtaining accurate heat transfer data using a variety of transient heat transfer measurement techniques under the extreme conditions of transonic flow and high heat transfer coefficient are presented.
The surfaces of interest are coated with wide-band thermochromic liquid crystals which cover the range of NGV surface temperature variation encountered in the test. The liquid crystal has a natural peak-to-peak roughness height of 25 μm creating a transitionally rough surface on the NGV. The time variation of colour is processed to give distributions of both heat transfer coefficient and film cooling effectiveness over the NGV surface. The NGV was first instrumented with the DHFGs and smooth surface tests preformed. Subsequently the surface was coated with liquid crystals for the rough surface tests. The DHFGs were then employed as the means of calibrating the liquid crystal layer. The roughness of 25 μm, which is the typical order of roughness for the in service turbine blades and vanes, increases the heat transfer coefficient by up to 50% over the smooth surface level. The film cooling effectiveness is influenced less by the roughness.
Rotor / Stator Heat Transfer Measurements and CFD Predictions for Short-Duration Turbine Rig Tests
Authors: Bergholz Robert F. , Dunn Michael G. , Steuber Gary D. 
Published: August 2014

This paper describes aerodynamic and heat transfer measurements, improved data analysis techniques, and CFD predictions for an extensive series of high-pressure turbine tests carried out in a large-scale, short-duration test facility. The focus of this work is on the test methods, aerodynamic and heat transfer instrumentation, and the heat flux data obtained on the HPT blade and vane pressure and suction surfaces, and on the blade platform. Heat transfer data are presented along three spanwise stream surfaces, and at five platform locations, for two Reynolds numbers, and for three different initial blade temperature levels. An analytical method for improving the interpretation of transient heat flux gage measurements and estimating the uncertainties in heat transfer coefficients is applied based on test facility characteristics, established 2D boundary layer heat transfer theory, and a detailed calculation of the transient temperature response of the heat flux gages as installed in the airfoils. The result is a systematic procedure for improved data reduction and correction of bias errors resulting from in-situ heat flux gage behavior in complex rotating rig tests. Three-dimensional aerodynamic calculations are compared with time-averaged unsteady pressure measurements on the airfoils. Boundary-layer heat transfer predictions are shown to be in fair agreement with the pitchline data but sensitive to assumptions regarding free-stream turbulence, uncertainties in inlet conditions, and variations in the applied surface Mach number distribution. Finally, full 3D heat transfer computations for the blade are discussed, with an emphasis on capturing overall 3D flow effects with sufficient accuracy for practical turbine airfoil cooling design. The results suggest that advanced analysis techniques, including 3D CFD, can be used effectively to compute not only mean values of the surface heat transfer coefficients, but also to quantify the uncertainties in the predictions and to identify the dominant sources of those uncertainties. This is an important step in creating a robust turbine cooling design process that accounts for environmental, manufacturing, and modeling variations.
Future papers will present experimental and computational results for the blade tip and shroud, the vane endwalls, and TBC-coated airfoils.
Effects of Turbulence and Solidity on the Boundary Layer Development in a Low Pressure Turbine
Authors: Solomon W. J. 
Published: August 2014

Multiple-element surface hot-film instrumentation has been used to investigate boundary layer development in the 2 stage Low Speed Research Turbine (LSRT). Measurements from instrumentation located along the suction surface of the second stage nozzle at mid-span are presented. These results contrast the unsteady, wake-induced boundary layer transition behaviour for various turbine configurations.
The boundary layer development on two new turbine blading configurations with identical design vector diagrams but substantially different loading levels are compared with a previously published result. For the conventional loading (Zweifel coefficient) designs, the boundary layer transition occurred without laminar separation. At reduced solidity, wake-induced transition started upstream of a laminar separation line and an intermittent separation bubble developed between the wake-influenced areas.
A turbulence grid was installed upstream of the LSRT turbine inlet to increase the turbulence level from about 1% for clean-inlet to about 5% with the grid. The effect of turbulence on the transition onset location was smaller for the reduced solidity design than the baseline. At the high turbulence level, the amplitude of the streamwise fluctuation of the wake-induced transition onset point was reduced considerably. By clocking the first stage nozzle row relative to the second, the alignment of the wake-street from the first stage nozzle with the suction surface of the second stage nozzle was varied. At particular wake clocking alignments, the periodicity of wake induced transition was almost completely eliminated.
Flow Visualisation in a Rotating Cavity With Axial Throughflow
Authors: Bohn Dieter E. , Deutsch Gregor N. , Simon Burkhard , Burkhardt Claus 
Published: August 2014

Annular cavities are found inside rotor shafts of turbomachines with an axial or radial throughflow of cooling air. In order to increase efficiency and system reliability, flow and heat transfer phenomena in those cavities have to be investigated in order to minimize thermal load. For research purposes an experimental rig is set up.
This paper focuses on flow visualisation using a laser light sheet technique in a heated rotating cavity which is axially flown through by cooling air. Flow phenomena are observed by a rotating telemetric video camera which shows smoke flowing through the light sheet area located in the axial midplane. The visualisation procedure is described and the first results are pointed out. Additionally, heat transfer measurement across the wall is shown.
Systematic Experimental and Numerical Investigations on the Aerothermodynamics of a Film Cooled Turbine Cascade With Variation of the Cooling Hole Shape: Part II — Numerical Approach
Authors: Hildebrandt Thomas , Ganzert Wolfgang , Fottner Leonhard 
Published: August 2014

An extensive numerical study was accomplished in order to accompany an experimental research program. The present work is focussed on the influence of the shape and the inclination of film cooling holes on the aerodynamic of the turbine cooling flow. Four different cooling hole geometries located on the suction side of a large scale turbine cascade were modelled and numerically simulated over the entire range of practically applicable blowing ratios. The thermodynamic conditions chosen, were in order to simulate comparable engine conditions.
Having computer limitations in mind, former simulations had to cope with either of two limitations. Meshing the entire domain led to an insufficient grid resolution in the vicinity of the ejection area, omitting valuable detailed flow information. In contrast, the so-called local approach (Vogel, 1996) overcame this problem by isolating an area close to the ejection zone, hence leading to a proper numerical resolution. A major drawback of this method is the required assumption for a limiting streamsurface, which often led to an inaccurate pressure distribution on the blade surface. Therefore, a new numerical technique in applying a 3D Navier-Stokes code on cooling flow problems — the global approach — was used, overcoming the restrictions of the above mentioned approaches. In the frame of these numerical investigations the commercially available CFD-package FINE™/Turbo by NUMECA was used.
The CFD-package incorporates a modern flow solver and the capability to perform multi-species computations, which was utilised herein. A second species (tracer gas) with the properties of air, was introduced, ejecting from the cooling plenum, hence strongly facilitating the visual detection of the emerging and dispersing cooling flow. The numerical resolution reached well over one million grid points.
The distributions of the tracer concentration and the oil and dye visualisations clearly reveal a strong dependency between the cooling hole shape and the efficiency of the film cooling. A considerable increase in the latter could be achieved, if non-cylindrical cooling hole geometries were used. The CFD simulations are in a very good agreement with the measurements (Ganzert, Hildebrandt and Fottner, 2000), clearly uncoveringvery detailed flow phenomena, which could also be detected in the experimental results. It was found out that the shape and the inclination angle of the cooling holes are of paramount importance to the distributing pattern of the cooling air and hence to the cooling efficiency.
Fog System Performance in Power Augmentation of Heavy Duty Power Generating Gas Turbines Model 7EA
Authors: Ingistov Steve 
Published: August 2014

Ambient air temperature plays significant role in performance of a Gas Turbine. Frequently Gas Turbines in electrical power generation are single rotor and are directly coupled to the Electrical Generators. These machines normally operate 8,000 hours per calendar year under the 100% load. The control of the combustion air flow is achieved by modulating compressor Inlet Guide Vanes (IGV). The single shaft axial compressor consumes as a rule of thumb more than 50% of turbine useful expansion work. Axial compressor is high-volume, moderate discharge pressure machine. Its power demand to discharge ambient air to the turbine combustion system is very dependent on ambient conditions such as pressure, temperature and relative humidity. The optimization of the axial compressor aerodynamic loading under various ambient conditions is therefore mandatory. During the hot and humid summer days, especially from the noon time to 6:00 PM, the demand for the power is at its maximum.
This Paper describes selection, design and installation of the Inlet Air Cooling System. (IACS). The selected IACS is fine water mist, FOG. FOG System (FS) was selected because of its efficiency and because the clean water was available. FS incorporates Fog Generating Skid (FGS) and Fog Curtain (FC). FC is comprised of lateral lines with equally spaced. FOG Nozzles (FN). The FN is specially designed to generate individual “Fog Cones” that efficiently dissipate the water particles in the space. Fine water particles are atomized by incoming air in the Inlet Air (IA) duct. The homogenous mixture of FOG and IA is required to enhance the water mist particles evaporation process. In cases when the FS works in tandem with Evaporative Cooler (EC) most of the FOG particles are “injected” into the compressor suction. The injected FOG particles start to evaporate during the IA compression process. The water evaporation process simultaneously causes cooling of the IA being compressed. The result is reduced compression work and improved performance of GT.
A Steady State Calculation Model for Gas Turbine Thermal Enclosures
Authors: Desideri Umberto , Di Maria Francesco 
Published: August 2014

Heavy duty and aeroderivative gas turbines for power generation and mechanical drive are installed inside an enclosure that is thermally and acoustically insulated and is equipped with fire extinguishing systems.
The enclosure is bolted on the gas turbine basement and is made of a steel frame that supports removable side panels, doors and roof sections.
All the fire extinguishing systems, lubricating oil pipes and electrical systems are fitted inside the enclosure and release, together with the gas turbine, a large amount of heat that has to be dissipated to avoid overheating of the gas turbine itself and its auxiliaries. Overheating of the enclosures is one of the main reasons for gas turbine unplanned stops.
For avoiding high internal temperatures, the enclosure is equipped with a cooling system consisting of pipes and fans, that extracts heat from the enclosure and limits the internal temperature increase.
This paper presents a calculation model developed for the study of the enclosure cooling system. Results are compared with experimental data measured on an aeroderivative gas turbine used as mechanical drive for a natural gas compression station, and acceptable correspondence is achieved.
Prediction of Low Engine Order Inlet Distortion Driven Resonance in a Low Aspect Ratio Fan
Authors: Marshall J. G. , Xu L. , Denton J. , Chew J. W. 
Published: August 2014

This paper presents a forced response prediction of 3 resonances in a low aspect ratio modern fan rotor and compares with other worker’s experimental data. The incoming disturbances are due to low engine-order inlet distortion from upstream screens. The resonances occur in the running range at 3 and 8 engine orders which cross low modes (flap, torsion and stripe) of the blade. The fan was tested with on-blade instrumentation at both on- and off-resonant conditions to establish the unsteady pressures due to known distortion patterns.
The resulting steady and unsteady flow in the fan blade passages has been predicted by three methods, all three-dimensional. The first is a linearised unsteady Euler method; the second is a non-linear unsteady Navier-Stokes method; the third method uses a similar level of aerodynamic modelling as the second but also includes a coupled model of the structural dynamics. The predictions for the 3 methods are presented against the test data, and further insight into the problem is obtained through post-processing of the data. Predictions of the blade vibration response are also obtained. Overall the level of agreement between calculations and measurements is considered encouraging although further research is needed.
Dynamic Coefficients of Labyrinth Gas Seals: A Comparison of Experimental Results and Numerical Calculations
Authors: Kwanka K. , Sobotzik J. , Nordmann R. 
Published: August 2014

Non-contacting labyrinth seals are still the most common constructive elements used to minimize leakage losses in turbomachinery between areas with high pressure and areas with low pressure. Unfortunately, the leakage flow through the labyrinth seal generates forces which can have a great impact on the dynamics of the turborotor. Particularly in cases of instability, the turbomachinery is restricted in its power or rotating speed because of violent self-excited vibrations of the rotor.
The occurrence of self-excited rotor vibrations due to lateral forces must definitely be excluded. To consider the labyrinth forces in Finite-Element prediction, a set of preferably exact dynamic coefficients is required. Numerical approaches used to calculate the coefficients are based on Navier-Stokes equations. A comparison with experimental data is essential for a validation of the calculation. The experimental identification is difficult, because of the littleness of the forces to be measured in gas seals. Especially the non-conservative coefficients, cross-coupled stiffness and direct damping, show a good agreement in both magnitude and trend depending on the entry swirl of the seal.
Direct Method for Optimization of a Centrifugal Compressor Vaneless Diffuser
Authors: Lee Yu-Tai , Luo Lin , Bein Thomas W. 
Published: August 2014

A Direct Method for Optimization (DMO) is developed for investigating pressure rise and energy loss in a vaneless diffuser of a generic compressor used in shipboard air-conditioning systems. The scheme uses Reynolds Averaged Navier-Stokes (RANS) results and evaluates gradients of a predetermined objective function. The current Direct Method for Optimization differs from the popular Inverse Design Method in the process of obtaining final configurations and in the final configurations obtained. The Direct Method for Optimization achieves a final shape from maximizing/minimizing a nonlinear function; i.e., the objective function. Both gradient and non-gradient Direct Methods for Optimization are compared with respect to accuracy and efficiency.
The coupled DMO/RANS optimization code is benchmarked using a plane turbulent diffuser also investigated by Zhang et al. using an adjoint method. The benchmark indicates that if a global optimum exists, the result should be independent of the methodologies or design parameters used.
The DMO/RANS method is applied to redesign a 3-D centrifugal vaneless diffuser used in a modern generic compressor. The objective function is a composite function of the diffuser’s pressure rise and total energy loss. The new optimum diffuser has a minimum width at a location far beyond the conventional diffuser pinch point. The new diffuser also provides an efficient section for pressure recovery, which takes place after the minimum width location. Test data for the new diffuser validates the current approach at the design condition. Furthermore, improved performance is also recorded experimentally at off-design conditions for the optimized diffuser.