bluuebunny/crossref_metadata_2025 huggingface dataset:
Status of Westinghouse’s Advanced Turbine Systems Program
Authors: Diakunchak Ihor S. , Krush Mark P. , McQuiggan Gerard , Southall Leslie R.
Published: December 2014

This paper describes the status of Westinghouse’s Advanced Turbine Systems (ATS) Program. This program was undertaken in response to U.S. Department of Energy, Office of Fossil Energy requirements for greater than 60% net plant thermal efficiency, less than 10 parts per million NOx emissions, 10% reduction in the cost of electricity and state-of-the-art Reliability-Availability-Maintainability (RAM) levels (Ali and Zeh, 1996). An extensive four-year program was undertaken to develop the required technologies and design an advanced gas turbine. The gas turbine design and most of the technology verification programs have been completed. The 501 ATS engine employed innovative aerodynamic, combustor, cooling, sealing, and mechanical designs, as well as advanced materials, coatings, and casting technologies to achieve the program goals. The incorporation of the 501 ATS gas turbine in a world-class combined cycle plant will result in more than 420 MW net output power and greater than 60% net LHV based plant thermal efficiency.
A New Low-Reynolds Number k-ε Model for Simulation of Momentum and Heat Transport Under High Free Stream Turbulence
Authors: Iyer Ganesh R. , Yavuzkurt Savash
Published: December 2014

A modified low-Reynolds number k-ε model for predicting effects of high free stream turbulence (FST) on transport of momentum and heat in a flat plate turbulent boundary layer is presented. An additional production term incorporating the effects of FST intensity (velocity scale) was included in the TKE equation. The constant cμ in the equation for the transport coefficient μt was modified using empirical information. These modifications were applied to two well tested k-ε models (Launder-Sharma and K-Y Chien,) under high FST conditions (initial FST intensity, Tui > 5%). Models were implemented in a two-dimensional boundary layer code. The high FST data sets against which the predictions (in the turbulent region) were compared had initial FST intensities of 6.53% and 25.7%. In a previous paper, it was shown that predictions of the original models became poorer (overprediction upto more than 50% for skin friction coefficient and Stanton number, and underprediction of turbulent kinetic energy (TKE) upto more than 50%) as FST increased to about 26%. In comparison, the new model developed here provided excellent results for TKE in the boundary layer when compared to the data set with Tui = 6.53%. Results for skin friction coefficient and Stanton number were also very good (within 2% of mean experimental data). For the case of data set with Tui = 25.7%, results of skin friction coefficient, Stanton number and TKE have also vastly improved, but still have scope for more improvement. The present model incorporates physics of free stream turbulence in turbulence modeling and provides a new method for simulating flows with high FST. Future work will focus on including length scale effects in the current model to obtain better predictions for the higher intensity case (Tui = 25.7%) and simulate flows typical in gas turbine engine environments.
Achieving Acoustical and Structural Requirements for Gas Turbine Packages While Reducing Costs, Pressure Losses, and Weight
Authors: Marcussen J. M. Anders
Published: December 2014

The Norwegian Offshore Market has shown itself to be a market leader in introducing new requirements and technological innovations in the gas turbine packages used on new installations.

This paper will review the changes that Altair Norge A/S has been a party to in the areas of “acoustics”, “reduction in pressure losses”, “reductions in weight”,” and an overall effort to reduce the “costs”.

The systems effected by the above changes are Inlets, Ventilation, Enclosures, and Exhausts. The time span of this review is from 1981 to the present; with the emphasis on the last 5 years.

It will be shown how the requirements generated by the authorities to protect the employees offshore generate benefits technologically.
A Hybrid Coupling Scheme and Stability Analysis for Coupled Solid/Fluid Turbine Blade Temperature Calculations
Authors: Heselhaus Andreas
Published: December 2014

Efficient thermal design of turbine blade cooling needs to take wall temperature effects on heat transfer into account. This can only be achieved by a coupled calculation of hot gas flow and blade heat conduction. In this paper principle and stability proof of an algorithm are presented that allows to couple a steady state finite element heat conduction solver with a blockstructured steady state finite volume (FV) Navier-Stokes time marching flow solver. The stability of the developed coupling procedure as well as the instability of an alternative algorithm is shown analytically and numerically. The benefits of coupled calculating are shown for a convectively cooled turbine guide vane blade. In the example treated, temperature differences of more than 100 K arise compared to the same calculation performed in an uncoupled way.
Correlations of the Convective Heat Transfer in Annular Channels With Rotating Inner Cylinder
Authors: Jakoby Ralf , Kim Soksik , Wittig Sigmar
Published: December 2014

In the internal air system of gas turbine engines or generators, a large variety of different types of annular channels with rotating cylinders are found. Even though the geometry is very simple, the flow field in such channels can be completely three-dimensional and also unsteady. From the literature it is well-known, that the basic two-dimensional flow field breaks up into a pattern of counter-rotating vortices, as soon as the critical speed of the inner cylinder is exceeded. The presence of a superimposed axial flow leads to a helical shape of the vortex pairs, which are moving through the channel.

For the designer of cooling air systems there are several open questions. Does the formation of a Taylor-vortex flow field significantly affect the convective heat transfer behaviour of the channel flow? Is there a stability problem even for high axial Reynolds-numbers and where is the location of the stability boundary? After all, the general influence of rotation on the heat transfer characteristics has to be known.

By the results of flow field and heat transfer measurements, the impact of rotation and the additional influence of Taylor-vortex formation on the heat transfer characteristics in annular channels with axial throughflow will be discussed. The flow field was investigated by time-dependant LDA-measurements, which revealed detailed information about the flow conditions. By a spectral analysis of the measured data, the different flow regimes could be identified. Based on these results, the heat transfer from the hot gas to the rotating inner shaft was determined with a steady-state method. Thus, the influence of the different physical phenomena such as rotation with and without Taylor-vortex formation or the flow development could be separated and quantified. Finally, correlations of the measured results were derived for technical applications.
Development of a Combustor Liner Composed of Ceramic Matrix Composite (CMC)
Authors: Nishio Kozi , Igashira Ken-ichiroh , Take Koji , Suemitsu Takeshi
Published: December 2014

The Research Institute of Advanced Materials Gas-Generator (AMG), which is a joint effort by the Japan Key Technology Center and 14 firms in Japan, has, since fiscal year 1992, been conducting technological studies on an innovative gas generator that will use 20% less fuel, weigh 50% less, and emit 70% less NOx than the conventional gas generator through the use of advanced materials.

Within this project, there is an R&D program for applying ceramic matrix composite (CMC) liners to the combustor, which is a major component of the gas generator.

In the course of R&D, continuous SiC fiber-reinforced SiC composite (SiCF/SiC) was selected as the most suitable CMC for the combustor liner because of its thermal stability and formability.

An evaluation of the applicability of the SiCF/SiC composite to the combustor liner on the basis of an evaluation of its mechanical properties and stress analysis of a SiCF/SiC combustor liner was carried out, and trial SiCF/SiC combustor liners, the largest of which was 500mm in diameter, were fabricated by the filament winding and PIP (polymer impregnation and pyrolysis) method.

Using a SiCF/SiC liner built to the actual dimensions, a non-cooling combustion test was carried out and even when the gas temperature was raised to 1873K at outlet of the liner, no damage was observed after the test. Through our studies we have confirmed the applicability of the selected SiCF/SiC composite as a combustor liner.

In this paper, we describe the present state of the R&D of a CMC combustor liner.
Reduction of the Dynamic Load Capacity in a Squeeze Film Damper Operating With a Bubbly Lubricant
Authors: Diaz Sergio E. , San Andrés Luis A.
Published: December 2014

Squeeze film dampers (SFDs) are effective means to reduce vibrations and to suppress instabilities in rotor-bearing systems. However, at operating conditions while traversing critical speeds with large orbital whirl motions, ingestion and entrapment of air into the thin lands of SFDs generates a bubbly mixture (air in lubricant) which is known to reduce the dynamic film pressures and the overall damping capability. This pervasive phenomenon lacks proper physical understanding and sound analytical modeling. An experimental investigation to quantify the forced performance of a SFD operating with a controlled bubbly mixture is detailed. Tests are conducted in a constrained circular orbit SFD to measure the dynamic squeeze film pressures and journal motion at two whirl frequencies (8.33 and 16.67 Hz) as the air content in the mixture increases from 0% to 100%. The analysis of period-averaged film pressures reveals a zone of uniform low pressure of magnitude equal to the discharge pressure, independently of the mixture composition. The uniform pressure zone extends as the mixture void fraction increases. Radial and tangential film forces are estimated from the dynamic pressures at two axial locations of measurement. The tangential (damping) force decreases proportionally with the mixture volume fraction, while a radial hydrostatic force remains nearly invariant. The experimental results quantify effects previously known by qualitative description only, thus providing a benchmark towards the development of sound theoretical models.
Heat Transfer in a Rotating Cavity With a Stationary Stepped Casing
Authors: Mirzaee Iraj , Quinn Paul , Wilson Michael , Owen J. Michael
Published: December 2014

In the system considered here, corotating “turbine” discs are cooled by air supplied at the periphery of the system. The system comprises two corotating discs, connected by a rotating cylindrical hub and shrouded by a stepped, stationary cylindrical outer casing. Cooling air enters the system through holes in the periphery of one disc, and leaves through the clearances between the outer casing and the discs.

The paper describes a combined computational and experimental study of the heat transfer in the above system. In the experiments, one rotating disc is heated, the hub and outer casing are insulated, and the other disc is quasi-adiabatic. Thermocouples and fluxmeters attached to the heated disc enable the Nusselt numbers, Nu, to be determined for a wide range of rotational speeds and coolant flow rates.

Computations are carried out using an axisymmetric elliptic solver incorporating the Launder-Sharma low-Reynolds-number k-ε turbulence model. The flow structure is shown to be complex and depends strongly on the so-called turbulent flow parameter, λT, which incorporates both rotational speed and flow rate. For a given value of λT, the computations show that Nu increases as Reϕ, the rotational Reynolds number, increases. Despite the complexity of the flow, the agreement between the computed and measured Nusselt numbers is reasonably good.
Effects of Periodic Wake Passing Upon Flat-Plate Boundary Layers Experiencing Favorable and Adverse Pressure Gradient
Authors: Funazaki Ken-ichi , Koyabu Eitaro
Published: December 2014

This paper deals with the investigation of wake-disturbed boundary layer on a flat-plate model with an elliptic leading edge. The wakes are generated by the transversely moving bars in front of the test model. Main focus of this paper is on how the wake passage affects the transitional behavior of the boundary layer under the influence of favorable and adverse pressure gradients over the test surface. Detailed measurements of the boundary layer are conducted by use of a hot-wire anemometry. An ensemble-averaging technique is also employed in order to extract the periodic events associated with the wake passage from the acquired data. The previously observed dependence of wake-induced transition on the movement of the wake generating bar is confirmed. It is also found that the wake passage induces a significant change in the flow structure downstream of the flow acceleration region.
Practical Use of 3D Inverse Method for Compressor Blade Design
Authors: Damle S. , Dang T. , Stringham J. , Razinsky E.
Published: December 2014

The practical utility of a 3D inverse viscous method is demonstrated by carrying out a design modification of a first-stage rotor in an industrial compressor. In this design modification study, the goal is to improve the efficiency of the original blade while retaining its overall aerodynamic, structural and manufacturing characteristics. By employing a simple modification to the blade pressure loading distribution (which is the prescribed flow quantity in this inverse method), the modified blade geometry is predicted to perform better than the original design over a wide range of operating points, including an improvement in choke margin.
Alternative Fuels for Gas Turbine Plants — An Engineering, Procurement, and Construction Contractor’s Perspective
Authors: Narula Ram G.
Published: December 2014

Tightly regulated and state-controlled utilities are rapidly changing into a competitive, market-driven industry, as private power development is being actively pursued worldwide. Accelerated economic growth in developing countries has fueled a massive growth in the power sector. Gas turbine based power plants have become an attractive option; however, many of these developing countries have limited supplies of conventional gas turbine fuels, namely natural gas or distillate oil. Therefore, power developers are seeking alternative fuels. This paper discusses the balance-of-plant (BOP) considerations and economics of using alternative fuels such as liquefied natural gas (LNG), liquefied petroleum gas (LPG), naphtha, and crude/heavy oils.
A Viscous Transonic Inverse Design Method for Turbomachinery Blades: Part I — 2D Cascades
Authors: Tiow W. T. , Zangeneh M.
Published: December 2014

An inverse design methodology is presented for the design of turbomachinery blades using a cell-vertex finite volume time-marching algorithm in transonic viscous flow. In this method the blade shape is designed subject to a specified distribution of pressure loading (the difference in pressure across the blade) and thickness distribution. The difference between specified pressure loading and the pressures on the initial blade shape results in a normal velocity through the blade, which is then used to update the blade shapes. Viscous effects are represented by using a distributed body force.

A simple and fast iterative scheme is proposed for automatically finding a suitable pressure loading that will provide a specified flow turning (or specific work). The method, therefore, can be applied to the design of new blade geometry without any need to supply information on the initial blade geometry or the blade loading corresponding to an existing design.

The Euler solver is first validated by using experimental data for a turbine stage. The accuracy of the inverse procedure is then verified by designing the stator blade from the computed pressure loading. Finally the method is applied to the design of an axial transonic turbine stator and an axial compressor rotor and stator blade.
The Effect of the Inlet Boundary Layer on the Tip Flow Field in a Transonic Fan Rotor
Authors: Takado Junji , Sonoda Toyotaka , Nakamura Satoshi
Published: December 2014

Experimental and numerical investigations have been carried out to understand the effects of the inlet boundary layer (IBL) on the tip flow field including the aerodynamic performance in a transonic fan rotor. Both the steady and the unsteady phenomena in the tip flow field have been investigated for operating conditions near peak efficiency and near stall with the two types of tip IBL. In order 10 study these phenomena, high response pressure data with Kulite transducers and laser doppler velocimeter (LDV) data have been acquired around the tip region. Furthermore, three-dimensional Navier-Stokes numerical simulations have been compared with the measured results. The results indicate that the tip IBL significantly influences the spanwise distribution of pressure ratio around the tip region and the stall characteristics including the passage shock / tip leakage vortex interaction, the blockage generation, the wake structure, and the unsteadiness of the tip flow field. In particular, at a near stall condition for the thick IBL with high turbulence intensity level, the tip diffusion level is increased due to a larger blockage, which is generated downstream of a much stronger interaction region. These phenomena are a consequence of the low momentum fluid in the tip IBL, and significantly reduce the stall margin. Furthermore, the unsteadiness drastically increases around the interaction region and around the pressure surface where the blockage migrates. These unsteady phenomena are distinctive features near stall. Downstream of the rotor, the larger and more unsteady blockage is discharged from the pressure surface side, and complicates the three-dimensional rotor exit flow field around the tip region.
Advanced Aeroderivative Gas Turbines in Coal-Based High Performance Power Systems (HIPPS)
Authors: Robson F. L. , Seery D. J.
Published: December 2014

The Department of Energy’s Federal Energy Technology Center (FETC) is sponsoring the Combustion 2000 Program aimed at introducing clean and more efficient advanced technology coal-based power systems in the early 21st century. As part of this program, the United Technologies Research Center has assembled a seven member team to identify and develop the technology for a High Performance Power Systems (HIPPS) that will provide in the near term, 47% efficiency (HHV), and meet emission goals only one-tenth of current New Source Performance Standards for coal-fired power plants. In addition, the team is identifying advanced technologies that could result in HIPPS with efficiencies approaching 55% (HHV).

The HIPPS is a combined cycle that uses a coal-fired High Temperature Advanced Furnace (HITAF) to preheat compressor discharge air in both convective and radiant heaters. The heated air is then sent to the gas turbine where additional fuel, either natural gas or distillate, is burned to raise the temperature to the levels of modern gas turbines. Steam is raised in the HITAF and in a Heat Recovery Steam Generator for the steam bottoming cycle. With state-of-the-art frame type gas turbines, the efficiency goal of 47% is met in a system with more than two-thirds of the heat input furnished by coal. By using advanced aeroderivative engine technology, HIPPS in combined-cycle and Humid Air Turbine (HAT) cycle configurations could result in efficiencies of over 50% and could approach 55%.

The following paper contains descriptions of the HIPPS concept including the HITAF and heat exchangers, and of the various gas turbine configurations. Projections of HIPPS performance, emissions including significant reduction in greenhouse gases are given. Application of HIPPS to repowering is discussed.
Film Cooling Heat Transfer: Shaped and Compound Angle Hole Injection
Authors: Seager David J. , Liburdy James A.
Published: December 2014

To further understand the effect of compound angle holes and hole shaping on film cooling, detailed heat transfer measurements were obtained using a hue based thermochromic liquid crystal method. This technique is fully described based on its development for film cooling applications. The data were analyzed to determine both the full surface adiabatic effectiveness and the heat transfer coefficient. The compound angles that are presented consist of holes aligned at 0° (streamwise) and 45° to the main cross flow direction. Hole shaping variations from the traditional cylindrically shaped hole include forward diffused and laterally diffused hole configurations. The length to diameter ratio (L/D) was 4.0, the pitch to diameter ratio (P/D) was 3.0, and the inclination angle (α) was 35°. A density ratio (DR) of 1.55 was obtained for all tests using carbon dioxide as the injection fluid into an air stream. For each set of conditions the blowing ratio (M) was varied to be 0.88, 1.25, and 1.88. Adiabatic effectiveness was obtained using a steady state test, while an active heating surface (constant, uniform heat flux) was used to determine the heat transfer coefficient using a transient method.
A Momentum Integral Method to Predict the Frictional Torque of a Rotating Disk With Protruding Bolts
Authors: Gärtner W.
Published: December 2014

A momentum integral method was developed to predict the frictional torque of a disk rotating in quiescent air with cylindrical protrusions mounted on its surface.

The predicted torque is compared to experimental data taken for the protrusions placed on two different radii on the disk with two different numbers of protrusions on each radius.

A critical review of the calculated results reveals that caused by the protrusions the predicted thickness of the boundary layer on the disk is of the same magnitude as the radius of the disk. Since in this case Prandtl’s simplifications for the boundary layer on which the momentum integral equations are based upon are not valid their use appears to be doubtful.

However, the predicted frictional torque is in good agreement with the measurements for all configurations tested except for that with the smallest circumferential distance between the protrusions where the torque is overpredicted by the method.

The application of the method for a disk rotating in a stationary housing is briefly discussed.
A Numerical Study of Air Transfer From a Stationary to a Rotating System Through an Unsealed Cavity
Authors: Jennions Ian K. , Sommer Thomas P. , Vasiliev Vladimir
Published: December 2014

An arrangement for transferring air from a stationary to a rotating system, proposed several years ago by the Saturn Design and Manufacturing Corporation (Moscow, Russia), has been studied numerically. The 3-D turbulent flow was calculated using a commercial CFD code which allowed identification of the major flow structures in this complex rotating flow. The calculations were compared with the available experimental data and show the ability of CFD to predict the integral characteristics with reasonable accuracy. An hydraulic model for performance predictions was developed and is also presented.
Design and Development of a Nine Stage Axial Flow Compressor for Industrial Gas Turbines
Authors: Stringham G. D. , Cassem B. N. , Prince T. C. , Yeung P. F.
Published: December 2014

A nine stage industrial axial flow compressor with a pressure ratio of 9.1:1 was designed, built and rig tested. The modern technology and design tools developed by government/aircraft engine compressor technologists were used for an industrial gas turbine application. The compressor was designed with “arbitrary” airfoil blading including CFD analysis in all blade rows. Flowpath contouring in the hub region of the rotors was used to decrease losses. The compressor rig was tested at the Compressor Research Facility at Wright Patterson Air Force Base in Dayton, Ohio. Extensive testing included determining the impact of stator leading edge instrumentation on performance. The compressor demonstrated excellent efficiency and stall margin in its first build. This paper describes the aerodynamic design, test instrumentation and test results.
VECTOR Program Background and Plan
Authors: Schondel J. Patrick , Robinson Michael R.
Published: December 2014

The U.S. Navy in cooperation with the Ministries of Defense of Germany and Sweden are initiating a 3-year demonstration program in 1998 to evaluate and define the benefits of thrust vectoring beyond those already understood for Close-in-Combat (CiC). The VECTOR (Vectoring ESTOL Control and Tailless Operational Research) program will capitalize on the X-31 airframe and a contractor team that includes Boeing, G.E., DASA, Volvo, and SAAB to demonstrate the following technologies:

• AVEN® Nozzle - a G.E. designed vectoring nozzle applicable to the F404 family of engines

• Extremely Short Takeoff and Landing (ESTOL) - employ thrust vectoring and precision control for poststall flight in approach to landing and during take off

• Reduced Tail/Tailless - rely on thrust vectoring for primary aircraft stability and control

• Advanced Air Data System (AADS) - flush air data ports or optical air data system integrated with the control system to handle the extensive angle-of-attack and sideslip envelope.

The flight test activity will be conducted in the United States. However, technical development activities will be conducted in all three countries. Germany and Sweden will contribute technical expertise primarily related to flight control and propulsion system integration, respectively.
Determination of Optimal Row Spacing for a Staggered Cross-Pin Array in a Turbine Blade Cooling Passage
Authors: Donahoo E. E. , Kulkarni A. K. , Belegundu A. D. , Camci C.
Published: December 2014

Crosspin configurations are of interest in turbine blade design due to the enhanced cooling they provide. In addition, crosspins which extend from the walls of hollow blades provide structural integrity and stiffness to the blade itself. Numerous crosspin shapes and arrangements are possible, but only certain combinations offer high heat transfer capability while maintaining low overall total pressure loss. This study presents results from 2-D numerical simulations of coolant airflow through a turbine blade internal cooling passage. The simulations model viscous flow and heat transfer over circular pins in a staggered arrangement of varying pin spacing. Preliminary analysis over a wide range of Reynolds numbers indicates existence of an optimal spacing for which maximum heat transfer and minimum total pressure drop occurs. Pareto plots, which graphically identify the optimum data points with multiple optimization parameters, were obtained for a range of Reynolds numbers and streamwise soarings in a staggered crosspin arrangement. There is a steady increase in crosspin heat transfer up to a certain number of rows, then a gradual decrease in heat transfer in subsequent rows. Knowledge obtained from such findings can be used to determine the number of crosspins used, as well as the ultimate pin arrangement.
A Frequency Domain Analysis: Turbine Pressure Side Heat Transfer
Authors: Holmberg D. G. , Diller T. E. , Ng W. F.
Published: December 2014

Simultaneous time-resolved surface heat flux and velocity measurements have been made along the pressure side of an engine-similar turbine blade in a linear cascade. Direct heat flux was measured using inserted Heat Flux Microsensors at three axial locations along the high turning transonic blade. Miniature hot-wires measured velocity above these locations. Grids produced two turbulence fields with different inlet length scales at constant turbulence intensity.

This work allows a unique look at fluctuating heat transfer on the blade and its relationship to the fluctuating velocity field above. While fluctuating free-stream flow energy and length scale decays continuously in the passage, surface heat flux energy increases continuously. Low frequency flow energy is attenuated in the constricted passage, while growth of low frequency energy in the heat flux is attributed to boundary layer transition activity. Coherence between heat flux and velocity is seen at all frequencies near the leading edge of the blade but only at higher frequencies farther downstream on the pressure side. Existing mean heat transfer correlations do not perform well in this complicated flow.
Fault Detection and Isolation Based on Dynamic Observers Applied to Gas Turbine Control Sensors
Authors: Simani S. , Spina P. R. , Beghelli S. , Bettocchi R. , Fantuzzi C.
Published: December 2014

In order to prevent machine malfunctions and to determine the machine operating state, it is necessary to use correct measurements from actual system inputs and outputs. This requires the use of techniques for the detection and isolation of sensor faults.

In this paper an approach based on analytical redundancy which uses dynamic observers is suggested to solve the sensor fault detection and isolation problem for a single-shaft industrial gas turbine. The proposed technique requires the generation of classical residual functions obtained with different observer configurations. The diagnosis is performed by checking fluctuations of these residuals caused by faults.
An Overview of Recent Clean Coal Gasification Technology R&D Activities Supported by the European Commission
Authors: Minchener A. J.
Published: December 2014

Gasification combined cycle has the potential to provide a clean, high efficiency, low environmental impact power generation system. A prime fuel for such systems is coal but there is scope in part to utilise renewable energy sources including biomass and waste materials such as sewage sludge or even oil residues. There is considerable scope to improve the performance of the first generation systems of gasification combined cycle plant, both through design changes and through the continued development towards second generation plant. Such improvements offer the prospect of even better efficiency, coal/biomass/waste utilisation flexibility, lower emissions especially of CO2, and lower economic cost of power generation. There have been several major R&D initiatives, supported in part by the European Commission, which have been designed to meet these aims. The approach adopted has been to form multi-partner project teams comprising industry, industrial research organisations and selected universities. The main technical issues that have been considered include co-gasification, e.g. co-feeding, fuel conversion, gas quality, contaminants, component developments, and the integration of hot fuel gas cleaning systems for removal of solid particles, control of sulphur emissions, control of fuel bound nitrogenous species, removal of halides and control of alkali species. The technical R&D activities have been underpinned by several major techno-economic assessment studies. This paper provides an overview of these various activities which either form part of the European Commission JOULE Coal R&D Programme or were supported under an APAS special initiative.
An Investigation of the Formation and Venting of Flammable Mixtures Formed Within Liquid Fuel Vessels
Authors: Bunama R. , Karim G. A. , Zhang C. Y.
Published: December 2014

The paper describes results of a parametric study obtained while using an analytical model described earlier (Bunama and Karim, 1997b) investigating the combined effects of mass, energy and momentum transfer with variable transport and thermodynamic properties on the formation of fuel vapour-air mixtures above a stagnant liquid fuel surface within the confines of a vertical cylindrical vessel. This was done mainly to examine the establishment of the formation of flammable mixtures and their changes in size and location with time within liquid fuel tanks that are partially empty. The effects of changes in the ambient and wall temperatures, presence of liquid on the walls and vessel geometry were considered. Moreover, the results of a corresponding experimental investigation are presented. Much of the data relates to the high volatility fuel n-pentane that represents the tighter fuel fractions in commercial fuels which through their early evaporation contribute much to the fire hazards in fuel tanks.
Performance Benefit Assessment of Ceramic Components in an MS9001FA Gas Turbine
Authors: Grondahl Clayton M. , Tsuchiya Toshiaki
Published: December 2014

The introduction of a ceramic gas turbine component in commercial power generation service will require significant effort. A careful assessment of the power plant performance benefit achievable from the use of ceramic components is necessary to rationalize the priority of this development compared to other alternatives. This paper overviews a study in which the performance benefit from ceramic components was evaluated for an MS9001FA gas turbine in a combined cycle power plant configuration. The study was performed with guidelines of maintaining constant compressor inlet airflow and turbine exit NOx emissions, effectively setting the combustion reaction zone temperature. Cooling flow estimates were calculated to maintain standard design life expectancy of all components.

Monolithic silicon nitride ceramic was considered for application to the transition piece, stage one and two buckets, nozzles and shrouds. Performance benefit was calculated both for ceramic properties at 1093C (2200F) and for the more optimistic 1315C (2400F) oxidatian limit of the ceramic. Hybrid ceramic-metal components were evaluated in the less optimistic case.
Impact of Variable-Geometry Stator Hub Leakage in a Low Speed Axial Compressor
Authors: Barankiewicz Wendy S. , Hathaway Michael D.
Published: December 2014

The impact of hub leakage flow associated with the clearance gaps of hub-shrouded variable-geometry stator rows in axial compressors is investigated experimentally. The objectives of this work are to investigate the sensitivity of performance to chordwise leakage location and to provide guidance for the mechanical design of variable stator hub trunions. Although blade loading near the hub is increased when leakage occurs at the leading edge, losses also increase for both design and off-design operating conditions. Leading edge leakage also causes a greater spanwise variation in absolute turning angle over the first 20% of span from the hub. Results show that for a moderately separated stator, the optimum leakage configuration features trailing edge leakage with the leading edge sealed. This confirms the current practice of most engine companies in placing the hub trunion at the blade leading edge.
Experimental Investigation on Impingement Heat Transfer From Rib Roughened Surface Within Arrays of Circular Jet: Effect of Geometric Parameters
Authors: Haiping Chang , Jingyu Zhang , Taiping Huang
Published: December 2014

Impingement heat transfer from rib roughened surface within two-dimensional arrays of circular jet with initial crossflow has been investigated experimentally. The configurations considered are intended to simulate the impingement cooled midchord region of the gas turbine airfoils in case where an initial crossflow is present. Many factors affect the heat transfer. The relative positions of the jet hole to the ribs and the geometric parameters have the significant effect on the heat transfer characteristics and have been experimentally studied. The investigation on the effect of the relative position of the jet hole to the ribs has been presented in an other paper. The effects of the geometric parameters such as jet hole spacing, jet-to-surface spacing, rib pitch-to-height ratio and rib height-to-hole diameter ratio on the heat transfer characteristics are considered in this paper. The experimentation is conducted under the conditions of Reynolds number 7,000–15,000 and the crossflow-to-jet mass flux ratio based on each channel/jet hole area 0∼0.5. With three jet hole spacing to jet hole diameter ratios, five jet-to-surface spacings, three rib pitch-to-height ratios and three rib height-to-hole diameter ratios, a great number of experimental data has been obtained. Based on this, the effects of the geometric parameters on the heat transfer characteristics have been obtained qualitatively and quantitatively. It can be used for evaluating the efficiency of the impingement heat transfer.
Explosion Hazards at Gas Turbine Driven Power Plants
Authors: Santon Roger C.
Published: December 2014

Combined Heat and Power and Combined Cycle Gas Turbine plants have become larger and more popular in recent years for local power and heat generation, and for main stream power generation. Many are based on gas turbines within acoustic enclosures. Complex fuel supply pipework to the turbines at high pressure gives rise to an explosion hazard within such enclosures in the event of foreseeable small leaks if appropriate ventilation is not provided. Health and Safety Executive investigations have exposed poor ventilation in some cases to the extent that explosion relief or significantly improved ventilation has been required. The paper describes the investigations, with reference to incident data, ignition probability, current relevant standards, and ventilation performance modelling by computational fluid dynamics. Suggested criteria for the evaluation of existing and new plant, and risk reduction measures, are described.
Application of a Micro-/Macro-Mixing Two Reactor Model to a Single-Cup Low-Emissions Combustor
Authors: Held T. J. , Mongia H. C. , Tonouchi J. H.
Published: December 2014

During the preliminary design and analysis phase of a gas turbine combustor, trade studies of the effects of design variables on emissions and operability are necessary to ensure a successful design. Due to the considerable resources required for full computational combustion dynamics simulations, simplified design tools are required for rapid analysis of a large number of design variable combinations. In a previous paper, a semi-analytical model of a gas turbine combustor was described (Tonouchi, et al., 1997). The model employs a gas particle Monte Carlo technique to simulate the effects of finite-rate micro- and macro-mixing, including full detailed chemical kinetics (Bowman, et al., 1997). Initial model validation work focused on emissions calculations for conventional rich dome combustors. This work presents NOx and CO emissions calculations for a single-cup natural gas-fired dry low emissions (DUE) combustor, and comparison to experimental data. The effect of parametric variation of the micro- and macro-mixing model constants, assigned volumes of the primary and secondary zones, and inlet unmixedness on the results are also presented.
Biomass Charcoal Co-Firing With Coal
Authors: Arcate James R.
Published: December 2014

Many biomass power plants operating today are small plants characterized by low efficiencies. The average biomass power plant is 20 MW with a biomass-to-electricity efficiency of about 20 percent. Small biomass power plants are also costly to build. Co-firing biomass with coal in existing large, low cost, base load pulverized coal (PC) power plants has been suggested as a cost-effective, near term opportunity for biomass power. However, co-firing of biomass in PC boilers requires addition of a separate biomass feed system. The proposed concept avoids a separate feed system by converting biomass to charcoal for co-firing with coal. Fuel supply reliability would be improved by producing and stockpiling charcoal at dedicated facilities located off the power plant site. With an energy density similar to coal, charcoal could be transported more economically than biomass. Overall costs for co-firing charcoal and coal would be lower than systems co-firing biomass. Investment in Clean Coal Technologies could also be leveraged for biomass energy use by co-firing charcoal with coal in Integrated Gasification Combined Cycle (IGCC) and Pressurized Fluid Bed Combustion (PFBC) power systems.
Volatile, Low Lubricity Fuels in Gas Turbine Plants: A Review of Main Fuel Options and Their Respective Merits
Authors: Molière M. , Geiger F. , Deramond E. , Becker T.
Published: December 2014

While natural gas is achieving unrivalled penetration in the power generation sector, especially in gas-turbine combined cycles (CCGT), an increasing number of alternative fuels are in a position to take up the ground left vacant by this major primary energy. In particular, within the thriving family of liquid fuels, the class of volatile products opens interesting prospects for clean and efficient power generation in CCGT plants. Therefore, it has become a necessity for the gas turbine industry to extensively evaluate such new fuel candidates, among which: naphtha’s; kerosines; gas condensates; Natural Gas Liquids (NGL) and alcohols are the most prominent representatives. From a technical standpoint, the success of such projects requires both a careful approach to several specific issues (eg: fuel handling & storage, operation safety) and a clear identification of technological limits. For instance, while the purity of gas condensates meets the requirements of heavy-duty technologies, it generally appears unsuitable for aeroderivative machines.

This paper offers a succinct but comprehensive technical approach and overviews some experience acquired in this area with heavy duty gas turbines. Its aim is to inform gas turbine users/engineers and project developers who envisage volatile fuels as alternative primary energies in gas turbine plants.
A Numerical Study of the Influence of Grid Refinement and Turbulence Modelling on the Flow Field Inside a Highly Loaded Turbine Cascade
Authors: Hildebrandt Thomas , Fottner Leonhard
Published: December 2014

A thorough numerical study was conducted to simulate the flow field inside a highly loaded linear turbine cascade. The numerical investigation was focused on the secondary flow field as well as on the prediction of the overall design goals within reasonable accuracy limits. The influence of grid resolution was investigated in order to obtain detailed information about the requirements of a grid independent solution. Three different two-equation turbulence models were applied to two numerical grids of different resolution. Emphasis was laid on separating the influences of grid resolution and turbulence models. The Mach- and Reynolds numbers as well as the level of freestream turbulence were set to values typical of turbomachinery conditions.

The computational study was carried out using a 3D state-of-the-art blockstructured Navier-Stokes solver. The comparison of the numerical results with experiments clearly revealed the different degree of agreement between simulation and measurement.

This paper describes the application of a modern flow solver to a testcase which is relevant for practical turbomachinery design purposes. The agreement between the experiments and the results of the numerical study is good and in most cases well within the accuracy limits proposed by Strazisar and Denton (1995).

It was found out that the main effect on the quality of the computations is the resolution of the numerical grid. The finest grid used reached over one million points halfspan, showing clearly superior results compared with a coarser, though still fine grid. The influence of different turbulence models on the numerically obtained flow field was relatively small in comparison with the the grid influence.
Numerical Simulation of Impeller–Volute Interaction in Centrifugal Compressors
Authors: Hillewaert Koen , Van den Braembussche René A.
Published: December 2014

A numerical procedure to predict the impeller/volute interaction in a single-stage centrifugal compressor is presented. The method couples a three-dimensional unsteady flow calculation in the impeller with a three-dimensional time-averaged flow calculation in the volute through an iterative updating of the boundary conditions on the interface of both calculation domains.

The method has been used to calculate the flow in a compressor with an external volute at off-design operation. Computed circumferential variations of flow angles, total temperature and pressure are shown and compared with measurements. The good agreement between the predictions and measurements confirms the validity of the approach.
Boundary Layer Transition at High Levels of Free Stream Turbulence
Authors: Matsubara Masaharu , Alfredsson P. Henrik , Westin K. Johan A.
Published: December 2014

Transition to turbulence in laminar boundary layers subjected to high levels of free stream turbulence (FST) can still not be reliably predicted, despite its technical importance, e.g. in the case of boundary layers developing on gas turbine blades. In a series of experiments in the MTL-wind tunnel at KTH the influence of grid-generated FST on boundary layer transition has been studied, with FST-levels up to 6%. It was shown from both flow visualisation and hot-wire measurements that the boundary layer develops unsteady streaky structures with high and low streamwise velocity. This leads to large amplitude low frequency fluctuations inside the boundary layer although the mean flow is still close to the laminar profile. Breakdown to turbulence occurs through an instability of the streaks which leads to the formation of turbulent spots. Accurate physical modelling of these processes seems to be needed in order to obtain a reliable prediction method.
Three-Dimensional Analysis of a Multistage Compressor Flow Field
Authors: Elmendorf Wolfgang , Mildner Frank , Röper Ralf , Krüger Uwe , Kluck Michael
Published: December 2014

A 3D-Navier-Stokes solver was used to analyse the complete flow field of the 15-stage axial compressor of Siemens model V84.3A advanced gas turbine.

The paper presents the flow simulation including modelling of rotor tip clearances and bleeds for turbine cooling air supply. All computations were performed for coupled blade rows to account for the time averaged impact of interaction effects arising from adjacent airfoil rows. The evaluation of such two-blade-row calculations allows the update of the inlet boundary conditions for the following downstream two-blade-row combination. Successive computations from inlet guide vanes to exit stator thus yield the flow field of the whole compressor.

The main objective is the analysis of the numerical results. Special attention is given to the front stage, stage matching, endwall flow effects, tip leakage and the cooling air extractions. The comparison to experimental data of the full load gas turbine test facility generally shows a good agreement. The results demonstrate the reliability and power of a modern CFD tool to perform advanced design studies, geometry modifications and calibration of fast 2D-Codes more efficiently and less expensively than performing any physical experiments.
Analysis of Aspect Ratio Effects on Transonic Rotor Performance Using a 3D Viscous Solver
Authors: Buchanan Cecil R. , Emmerson Paul R. , Spruce Michael
Published: December 2014

This paper presents the results of a numerical study into the effects of aspect ratio on compressor rotor performance. The test cases studied are NASA rotors 37 and 38, which have aspect ratios of 1.19 and 1.63 respectively. A 3D, single-passage steady flow Navier-Stokes solver was used to predict complete performance characteristics, including the numerical instability point, for both rotors. The predictions are generally in good agreement with the test data (characteristics, radial profiles and rotor over tip measurements) at all conditions modelled for rotor 37. The performance for rotor 38 is overpredicted, with slightly less than half of the measured performance difference between the two rotors being captured. The effect of a pure aspect ratio change (divorced from the rotor inlet to exit area changes present in the rotor 37/38 comparisons) was also investigated, and a case with an aspect ratio double that of rotor 37 was also modelled. The results indicated that the code predicted little effect on rotor performance due to an aspect ratio change alone (from 1.19 to 2.38). This is surprising and it raises doubts about the ability of current codes (or at least the one used in the study) to predict this important aspect of a compressor design adequately.