bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Planning of a Super Waste Incineration Cogeneration Plant
Authors: Ito Koichi , Yokoyama Ryohei , Shimoda Makoto
Published: February 2015

This paper, is concerned with the evaluation of economic and energy saving characteristics of a super waste incineration cogeneration plant, which is equipped with gas turbines as topping cycle to overcome a drawback of low power generating efficiency of conventional waste incineration cogeneration plants only with steam turbines. Economic and energy saving characteristics are evaluated using an optimal planning method which determines capacities and operational strategies of constituent equipment from their many alternatives so as to minimize the annual total cost. Through a case study, advantages of a super waste incineration cogeneration plant are shown in comparison with a conventional one. A parametric study is also carried out with respect to the amounts of waste collected and energy distributed.
Optimum Power Boosting of Gas Turbine Cycles With Refrigerated Inlet Air and Compressor Intercooling
Authors: Ait-Ali Mohand A.
Published: February 2015

With or without turbine blade cooling, gas turbine cycles have consistently higher turbine inlet temperatures than steam turbine cycles. But this advantage is more than offset by the excessive compressor work induced by warm inlet temperatures, particularly during operation on hot summer days. Instead of seeking still higher turbine inlet temperatures by means of sophisticated blade cooling technology and high temperature-resistant blade materials, it is proposed to greatly increase the cycle net work and also improve thermal efficiency by decreasing the compressor work. This is obtained by using refrigerated inlet air and compressor intercooling to an extent which optimizes the refrigerated air inlet temperature and consequently the gas turbine compression ratio with respect to maximum specific net power.

The cost effectiveness of this conceptual cycle, which also includes regeneration, has not been examined in this paper as it requires unusually high pressure ratio gas turbines and compressors, as well as high volumetric air flow rate and low temperature refrigeration equipment for which reliable cost data is not easily available.
A 2-D Navier-Stokes Solution Method With Overset Moving Grids
Authors: Tuncer Ismail H.
Published: February 2015

A simple, robust numerical algorithm to localize moving boundary points and to interpolate unsteady solution variables across 2-D, arbitrarily overset computational grids is presented. Overset grids are allowed to move in time relative to each other. The intergrid boundary points are localized in terms of three grid points on the donor grid by a directional search algorithm. The parameters of the search algorithm give the interpolation weights at the localized boundary point. The method is independent of numerical solution algorithms and may easily be implemented on any 2-D, single block flow solver to make it a multi-block, zonal solver with arbitrarily overset computational grids. Computational results and comparisons with single grid solutions are presented for flows through a compressor cascade and over an airfoil undergoing a flapping motion. Excellent agreement is obtained against the single grid solutions.
A Rational Method for Optimizing Shroud Damping
Authors: Griffin J. H. , Labelle R. F.
Published: February 2015

A computer code, BDAMPER, was recently developed by Ohio State University researchers and can be used to predict the vibratory response of shrouded blades that contain friction interfaces. This paper discusses some modeling issues that arose in applying BDAMPER to actual blades and outlines a procedure for optimizing the shroud’s design in order to minimize the blade’s resonant response. A comparisons are made between BDAMPER predictions of blade response and experimental data taken from spin pit and engine tests.
Stability Analysis of Symmetrical Rotor-Bearing Systems With Internal Damping Using Finite Element Method
Authors: Forrai L.
Published: February 2015

This paper deals with the stability analysis of self-excited bending vibrations of linear symmetrical rotor-bearing systems caused by internal damping using the finite element method. The rotor system consists of uniform circular Rayleigh shafts with internal viscous damping, symmetrical rigid disks, and discrete undamped isotropic bearings. By combining the sensitivity method and the matrix representation of the rotor dynamic equations in complex form to assess stability, it is proved theoretically that the stability threshold speed and the corresponding whirling speed coincide with the first forward critical speed regardless of the magnitude of the internal damping.
The Effect of Reynolds Number on the Behaviour of a Leading Edge Separation Bubble
Authors: Hazarika Birinchi K. , Hirsch Charles
Published: February 2015

An experimental investigation of a separation bubble on a C4 leading edge plate at an incidence in a low turbulence free stream at six Reynolds numbers, is reported. The long separation bubble, formed at the leading edge, has a short laminar and transitional zone followed by a long turbulent zone. The increase in Reynolds number reduced the laminar and transitional part significantly, but its effect on the length of the separation bubble is marginal till the transition starts at the separation point. The peak intermittency factor, which occurs at the centre of the shear layer, follows the universal intermittency distribution curve. The spot production rate for the separated flows are several orders of magnitude higher than that for the attached boundary layers. The transition process is initiated by the amplification of the instability waves in the shear layer similar to the natural mode of transition. At high Reynolds numbers, the onset of transition is likely to take place at the separation point. At lower chord Reynolds numbers, the separation to onset Reynolds number and the spot production rate parameter are functions of the separation momentum thickness Reynolds number. The free stream turbulence intensity has a strong influence on the spot production rate. New correlations for transition in the leading edge separation bubbles are proposed based on all the available intermittency measurements in the leading edge separation bubbles.
Experimental Investigation and Theoretical Prediction of Flutter Behaviour of a Plane Cascade in Low-Speed Flow
Authors: Hennings H. , Send W.
Published: February 2015

The Institute of Aeroelasticity operates a test facility which enables aeroelastic investigations of plane cascades in low-speed flow. The test stand serves as a pilot facility to develop tools for analogous investigations in transonic flow. Eleven blades are elastically suspended in a windtunnel with a 1 × 0.2 m2 cross section.

This paper describes the experimental method of determining the flutter boundary by extrapolation of the results measured in subcritical flow. A 2D theoretical model of the 11 blades including the windtunnel walls permits the computation of unsteady pressures, forces and moments in close relation to the experiment. The prediction of flutter is compared with experimental results. In the present investigation, the motion of the blades is constrained to pitch around mid-chord. The vibrating blades are mechanically uncoupled. Any interaction between the blades is effected by the air stream, leading to a sensitive dependence on the aerodynamic forces.
Simulation of Performance Deterioration in Eroded Compressors
Authors: Singh Deepinder , Hamed Awatef , Tabakoff Widen
Published: February 2015

A simple model was developed to simulate axial flow compressor performance deterioration due to blade erosion. The simulation at both design and off-design conditions is based on a mean line row by row model, which incorporates the effects of blade roughness and tip clearance. The results indicate that the increased roughness reduces the pressure ratio as well as the adiabatic efficiency of the compressor at all speeds with the largest influence at 100% speed. Increased tip clearance has a more pronounced effect on the compressor adiabatic efficiency and a lesser effect on the pressure ratio. According to the obtained results the loss in compressor performance due to erosion increases with increased blade loading.
The Indirect Cycle: A Logical and Practical Nuclear Gas Turbine Power Plant Concept
Authors: McDonald Colin F.
Published: February 2015

Many variants of the nuclear closed Brayton cycle (NCBC) power plant have been studied over the last five decades, the ultimate goal being the introduction of a high efficiency and environmentally acceptable plant for electrical power generation. With an indirect cycle (IDC) plant the thermal energy from a high temperature reactor (HTR) is transferred to the helium gas turbine power conversion system via an intermediate heat exchanger. Compared with previous direct cycle variants the decoupling of the prime-mover from the reactor has the following advantages, 1) configuration flexibility (eased congestion), 2) good component access, 3) non radioactive power conversion system, 4) ease of maintenance, 5) use of conventional equipment, 6) reduced development effort, and 7) eased adaptability to a fossil-fired source. In addition to being a more practical configuration, a major attribute for the IDC is that it is compatible with long-term plans for development of a high temperature nuclear heat source (NHS) currently underway in Japan. With a NHS in place a logical progression of the HTR would be to deploy a power generation version using an IDC helium gas turbine. This paper sheds new light on the nuclear gas turbine in that it is no longer at the forefront of gas cooled reactor application studies, but rather could be a beneficiary of work currently underway in Japan to develop a nuclear heat source for high temperature process heat. The performance and major features of a future NCBC plant concept are highlighted in this paper. Depending on the market forces prevailing in Asia for small nuclear plants, the NCBC with an indirect cycle helium gas turbine could be available for service around the year 2020.
A Distortion Problem in a Single Shaft Military Turbojet
Authors: Kotsiopoulos Petros , Kottarakos Andreas , Pilidis Pericles
Published: February 2015

Compressor surge is one of the most worrisome in-flight emergencies that users have to face. The phenomenon is influenced by many parameters internal or external to the engine. The purpose of this paper is to describe an investigation into this matter prompted by the operating experience of the Hellenic Air Force. Initially, the most common destabilizing parameters had to be identified and their influence on engine handling was assessed.

The Hellenic Air Force has been facing compressor surge problems, mostly related to the use of the aircraft or the type of mission. The findings of this work give a semi-quantitative explanation of the events observed in practice.
Thermodynamic Design Point Study of a Semi-Closed Recuperated Intercooled Gas Turbine Combined With a Rankine Bottoming Cycle
Authors: Nemec Todd S. , Lear William E.
Published: February 2015

A design point study of a semi-closed recuperated intercooled gas turbine combined with a closed, unfired, Rankine cycle is presented to demonstrate the overall thermodynamic design and efficiency tradeoffs for this type of cycle. Through its semi-closed design, having control over combustor equivalence ratio and recirculation flow exit pressure, this cycle provides improvements in emissions, specific power (net system power output divided by gas turbine inlet airflow), part power thermal efficiency, and overall system size relative to a combined cycle with an open cycle gas turbine. The relationship of design variables to cycle and component selection is discussed. Interface heat exchanger configuration, along with bottoming cycle choices of regeneration, feedwater heating, and fluid (H2O or DOWTHERM®A) are evaluated to determine their effects on mechanical design and thermal efficiency.
Engine Test Experience With HVOF WC-Co Coated Fan Blade Dampers
Authors: Pejryd Lars , Wigren Jan
Published: February 2015

Tungsten carbide thermal spray coatings are important to the aerospace industry for reducing wear on jet engine components, fanblade mid-span dampers being one example. However, the fatigue life of a component is often reduced when a coating is applied and for some cases the coating can fail due to spallation and cracking. Coating failures can result in decreased engine performance and costly maintenance. To provide insight and possible explanations for the reduced service life of coated mid-span dampers, identify the best coating and application processes for future use, and to develop methods for improving coating performance, a comprehensive experimental research program was conducted. The program involved coating performance in jet engine tests, coating crack resistance in bending, low cycle fatigue properties of the coating and substrate, and microstructures for a wide range of coating compositions and application processes. Eleven coatings were ranked according to their performance relative to the other coatings in each evaluation category. Five of the coatings were selected for engine test runs. Results from the engine test runs for more than 800h (AMT-cycle) were compared to bend and low cycle fatigue evaluations and to meassured residual stresses. Strong correlation between engine performance and the residual stresses in the coating-substrate system was found. Results from the program were used for selecting a suitable coating system for final in-service use.
Predicting Marine Gas Turbine Engine Removals Using System Simulation
Authors: Bodman Thomas M.
Published: February 2015

This paper evaluates System Simulation as a technique for predicting the removal of US Navy Marine Gas Turbine Engines. The Navy’s Allison 501K17 engine provided the data for this study. The Allison 501K17 is used for electric power generation by the Navy. A System Simulation Model was constructed using the programing language GPSS/H. Forecasts were developed using the model for fiscal years 1990 thru 1995. The model generated 21 forecasts for each year. The sample mode and mean were calculated for each year from this data. The Navy currently uses a statistical technique for forecasting engine removals. The Statistical Forecast, the System Simulation Sample Mode Forecast and System Simulation Sample Mean Forecast were compared with the actual number of removals for fiscal years 1990 thru 1994. A Chi-Square analysis was conducted to determine the goodness of fit of the forecast to the actual removals. The Chi-Square analysis showed that none of the forecasting techniques accurately predicted the removals. Additional study needs to be conducted to find a forecasting technique that accurately predicts engine removals.
A Framework for Analyzing the Dynamics of Flexibly-Bladed Turbomachines
Authors: Gysling D. L. , Myers M. R.
Published: February 2015

A framework for analyzing the nonlinear dynamic behavior of flexibly-bladed turbomachines is presented. The analytical description is based on matching a two dimensional, incompressible flow field across a semi-actuator disk representation of a flexible rotor and a rigid stator. The aerodynamic loading on the rotor is derived using control volume formulations applied to discrete blade passages allowing consideration of finite interblade phase angles. Depending on operating parameters, the model exhibits behaviors classified as surge, rotating stall, and stall flutter which are qualitatively consistent with experimentally observed results.

The formulation provides a tractable, nonlinear, state-space description of the dynamics responsible for surge, rotating stall, flutter, and their interaction. An analysis is performed for system parameters representative of a fan in a modern high-bypass ratio aeroengine. The behavior of the operability limiting instability modes is examined using time simulations, eigenvalues plots and two-parameter stability diagrams.
Unsteady Flow Calculation in a Cross-Flow Fan Using a Finite Element Method
Authors: Bert P. F. , Pessiani M. , Combes J. F. , Kueny J. L.
Published: February 2015

In order to predict rotor-stator interactions in hydraulic turbomachinery, a new multidomain method was implemented in a turbulent flow finite element code. The formulation is based on the mortar element method, extended to sliding meshes. It allows the coupling between several domains using nonconforming discretization on the interface.

This method was used to study the unsteady flow in a cross-flow fan. Such fans are widely used in air-conditioning devices. They consist of a cylindrical rotor with forward curved blades, rotating in a housing. The air passes the blades twice at the inlet and the outlet of the impeller while a large vortex is noticeable inside the impeller which is located in the blading near the stabilizer.

The numerical results are compared to Laser Doppler Velocity measurements and to steady calculations obtained by replacing the blades by a rotating force field. The unsteady calculation shows the formation of the vortex structure at the start-up and the periodic established flow after a few revolutions of the impeller.
Adaptive Control of a Gas Turbine Engine for Axial Compressor Faults
Authors: Lombardo G.
Published: February 2015

An adaptive control system for a gas turbine engine which diagnoses conditions of axial compressor faults is proposed and analyzed. Nonlinear models of the gas turbine, neural networks and genetic algorithms are used in this research. The adaptive control system minimizes the reduction in gas turbine performance deriving from non-destructive faults. In the absence of faults, the system automatically performs the optimization of the engine between overhauls. Improvements concern the definition of adaptive control with faults in progress, and the real-time optimization of the engine during its operative life between overhauls. Simulation results of the suggested control system are also discussed.
Solid Oxide Fuel Cell Combined Cycles
Authors: Bevc Frank P. , Lundberg Wayne L. , Bachovchin Dennis M.
Published: February 2015

The integration of the solid oxide fuel cell (SOFC) and combustion turbine technologies can result in combined-cycle power plants, fueled with natural gas. that have high efficiencies and clean gaseous emissions. Results of a study are presented in which conceptual designs were developed for three power plants based upon such an integration, and ranging in rating from 3 to 10 MW net ac. The plant cycles are described, and characteristics of key components are summarized. In addition, plant design-point efficiency estimates are presented, as well as values of other plant performance parameters.
Rich-Quench-Lean Combustion for Multiple Fuels
Authors: Bachovchin Dennis M. , Domeracki William F.
Published: February 2015

Westinghouse has developed a rich-quench-lean gas turbine combustor for use on multiple gaseous fuels. The design is based on variants of the Multi-Annular Swirl Burner (MASB) that was invented as a low-NOx topping combustor for the second generation PFBC process, utilizing high temperature vitiated air and high temperature NH3-rich fuel gas, both derived from coal. This Westinghouse RQL combustor is also capable of low-NOx performance using either natural gas or propane in vitiated air, as well as compressor air operation using syngas (coal- or biomass-derived fuel gas for IGCC), propane, or natural gas. The current status of the Westinghouse RQL combustor with regard to each such application is discussed, including design basis, design status, test experience, and expected emissions and operating characteristics.
Development of Ceramic Gas Turbine Components for the CGT301 Engine
Authors: Hattori Mitsuru , Yamamoto Tsutomu , Watanabe Keiichiro , Masuda Masaaki
Published: February 2015

NGK Insulators, Ltd. (NGK) has undertaken the research and development on the fabrication processes of high-heat-resistant ceramic components for the CGT301, which is a 300kW recuperative industrial ceramic gas turbine engine. This program is under the New Sunshine Project, funded by the Ministry of International Trade and Industry (MITI), and has been guided by the Agency of Industrial Science & Technology (AIST) since 1988. The New Energy and Industrial Technology Development Organization (NEDO) is the main contractor.

The fabrication techniques for ceramic components, such as turbine blades, turbine nozzles, combustor liners, gas-path parts, and heat exchanger elements, for the 1,200°C engine were developed by 1993. Development for the 1,350°C engine has been underway since 1994. The baseline conditions for fabricating of all ceramic components have been established.

This paper reports on the development of ceramic gas turbine components, and the improved accuracies of their shapes as well as improved reliability from the results of the interim appraisal conducted in 1994.
A New Concept for the Design of Turbine Diffusers
Authors: Raab Irene , Lippert Dirk , Hennecke Dietmar K.
Published: February 2015

A new concept for annular diffuser design permits a layout of axial multi–diffusers with the potential to achieve the same pressure rise as single–annular diffusers, but over half the length. This is possible by using the full range of geometrical variability to gain a symmetrical loading for all flow channels. The optimal geometry with respect to the radial splitter position and the diffuser struts indicates strong dependence on the outflow of the leading turbine row, at the same time influencing this outflow by means of sharp wall angles. Moreover, an advantage can be derived from the additive pressure rise of the equalization process behind the diffuser. Therefore, it is no longer appropriate to treat the diffuser as an isolated component in the design process, but also to take into account the whole diffusion system including the turbine, diffuser and ducts. CFD turned out to be an adequate tool for this complex task.
Effects of Free-Stream Turbulence and Surface Roughness on Film Cooling
Authors: Schmidt Donald L. , Bogard David G.
Published: February 2015

A flat plate test section was used to study how high free-stream turbulence with large turbulence length scales, representative of the turbine environment, affect the film cooling adiabatic effectiveness and heat transfer coefficient for a round hole film cooling geometry. This study also examined cooling performance with combined high free-stream turbulence and a rough surface which simulated the roughness representative of an in-service turbine. The injection was from a single row of film cooling holes with injection angle of 30°. The density ratio of the injectant to the mainstream was 2.0 for the adiabatic effectiveness tests, and 1.0 for the heat transfer coefficient tests. Streamwise and lateral distributions of adiabatic effectiveness and heat transfer coefficients were obtained at locations from 2 to 90 hole diameters downstream.

At small to moderate momentum flux ratios, which would normally be considered optimum blowing conditions, high free-stream turbulence dramatically decreased adiabatic effectiveness. However, at large momentum flux ratios, conditions for which the film cooling jet would normally be detached, high free-stream turbulence caused an increase in adiabatic effectiveness. The combination of high free-stream turbulence with surface roughness resulted in an increase in adiabatic effectiveness relative to the smooth wall with high free-stream turbulence. Heat transfer rates were relatively unaffected by a film cooling injection. The key result from this study was a substantial increase in the momentum flux ratios for maximum film cooling performance which occurred for high free-stream turbulence and surface roughness conditions which are more representative of actual turbine conditions.
Experimental Investigation of Hybrid Airblast Atomizer
Authors: Chin J. S. , Rizk N. K. , Razdan M. K.
Published: February 2015

As a means of overcoming the difficulties of achieving a satisfactory fuel atomization over the entire range of engine operation, both airblast forces and high pressure fuel injection are used in one hybrid atomizer design. The objectives of the present effort are to further improve the understanding of the important process of spray interaction in the hybrid atomizer flowfield, and to develop a relatively simple calculation approach that can relate the net effect of the interaction to the atomizer operating conditions. The ratio of the calculated average SMD for both the pilot and main prefilming device of the hybrid atomizer, each operating separately, to the SMD measured for the overall spray, obtained when both fuel devices were operating simultaneously, was used as an indication of the interaction between the two sprays. The experimental investigation demonstrated that stronger interaction between the pilot pressure nozzle spray and the prefilming main spray of the hybrid airblast atomizer occurred at higher pilot fuel pressure, larger pilot spray angle, or lower air pressure drop. It was also noticed that there was an optimum value of main fuel pressure, beyond which a decline in spray interaction was observed. The results indicated that by carefully selecting the pilot spray angle and flow capacities of the atomization devices, satisfactory atomization could be achieved even at lower air pressure drop. The interaction between the pilot and main sprays of the hybrid atomizer in configurations that utilized air swirlers surrounding the atomizer, was strongly dependent on swirler geometry. The extent of the interaction was attributed to changes in the air flowfield around and between the two sprays and the main filming process, all significantly affected the degree of utilization of the airblast effects.
The Microstructure, Mechanical Properties and Coatability of Diffusion Brazed CMSX-4 Single Crystal
Authors: Miglietti Warren M. , Pennefather Ros C.
Published: February 2015

Diffusion brazing is a joining process utilized both in the manufacture and repair of turbine blades and vanes. CMSX-4 is an investment cast, single crystal, Ni-based superalloy used for turbine blading and vanes, and has enhanced mechanical properties at elevated temperatures when compared to equiaxed, directionally solidified and first generation single crystal superalloys. The objective of this work was to develop a diffusion brazing procedure to achieve reliable joints in the manufacture of a hollow turbine blade (for a prototype engine in South Africa), and to verify the coatability of the diffusion brazed joints. Two commercially available brazing filler metals of composition Ni-15Cr-3.5B and Ni-7Cr-3Fe-4.5Si-3.2B-0.06C and a proprietary (wide gap) braze were utilized. With the aim of eliminating brittle centre-line boride phases, the effects of temperature and time on the joint microstructure were studied. Once the metallurgy of the joint was understood, tensile and stress rupture tests were undertaken, the latter being one of the severest tests to evaluate joint strength. The results demonstrated that the diffusion brazed joints could satisfy the specified stress rupture criterion of a minimum of 40 hrs life at 925 °C and 200 MPa. After mechanical property evaluations, an investigation into the effects of a low temperature high activity (LTHA) pack aluminide coating and a high temperature low activity (HTLA) pack aluminide coating on the braze joints was undertaken. The results showed that diffusion brazed joints could be readily coated.
LDA Study of the Flow Development Through an Orthogonally Rotating U-Bend of Strong Curvature and Rib Roughened Walls
Authors: Iacovides H. , Jackson D. C. , Ji H. , Kelemenis G. , Launder B. E. , Nikas K.
Published: February 2015

This paper reports laser Doppler anemometry (LDA) and wall pressure measurements of turbulent flow in a square-sectioned, rotating U-bend typical of coolant passages employed in modern gas turbine blades. In the upstream and downstream tangents, the pressure and suction (inner and outer) surfaces are roughened with discrete square-sectioned ribs in a staggered arrangement for a rib-height to duct-diameter ratio of 0.1. Three cases have been examined at a passage Reynolds number of 105: a stationary case; a case of positive rotation (the pressure side coinciding with the outer side of the U-bend) at a rotation number (Ro=ΩD/Um) of 0.2; and a case of negative rotation at Ro=−0.2. Measurements have been obtained along the symmetry plane of the duct. In the upstream section, the separation bubble behind each rib is about 2.5 rib-heights long. Rotation displaces the high momentum fluid towards the pressure side, enhances turbulence along the pressure side and suppresses turbulence along the suction side. The introduction of ribs in the straight sections reduces the size of the separation bubble along the inner wall of the U-bend, by raising turbulence levels at the bend entry; it also causes the formation of an additional separation bubble over the first rib interval along the outer wall, downstream of the bend exit. Rotation also modifies the mean flow development within the U-bend, with negative rotation speeding up the flow along the inner wall and causing a wider inner-wall separation bubble at exit. Turbulence levels within the bend are generally increased by rotation and, over the first two diameters downstream of the bend, negative rotation increases turbulence while positive rotation on the whole has the opposite effect.
Thermocyclic Behavior of Variously Stabilized EB-PVD Thermal Barrier Coatings
Authors: Schulz U. , Fritscher K. , Peters M.
Published: February 2015

The demand for increasing gas inlet temperatures in modem gas turbines up to 1500°C and above is the main reason for the need for more reliable thermal barrier coatings. New ceramics should provide higher phase stability and better resistance against chemical attack by pollutants in the combustion gas.

Electron-beam physical vapor deposition (EB-PVD) processed, ZrO2-based TBCs were generated on bond-coated superalloy directionally solidified (DS) samples. Common yttria-stabilized zirconias of two different compositions, as well as novel stabilizers like CeO2 and La2O3 were investigated. A columnar structure was established during high-rate deposition in all cases. Diameter, degree of ordering of the columns and phase composition depended on stabilizer oxide and content. The role of differences of vapor pressures is addressed with regard to chemical homogeneity of the coatings.

The performance of the TBCs having various stabilizers was investigated in a cyclic oxidation furnace test and in a burner rig at Mach 0.3. The results were correlated to the type and content of stabilizer with special emphasis on phase analyses.

Evaporation of new ceramic compositions necessitates special precautions because the vapor pressures of the components may differ too much. A new dual-source evaporation coater allows the production of these innovative TBCs with close control of chemistry. The potential of the equipment will be discussed.
Effect of Rib Height and Pitch on the Thermal Performance of a Passage Disturbed by Detached Solid Ribs
Authors: Liou Tong-Miin , Shuy Woei-Jiunn , Tsao Yu-Houe
Published: February 2015

Laser holographic interferometry and pressure measurements are presented for the effects of rib-to-duct height ratio (H/2B), rib pitch-to-height ratio (Pi/H), and Reynolds number (Re) on the spatially periodic-fully developed turbulent heat transfer and friction in a rectangular duct of width-to-height ratio of 4:1 with an array of ribs detached from one wall at a clearance to rib-height ratio of 0.38. The range of H/2B, Pi/H, and Re examined were 0.13 to 0.26, 7 to 13, and 5×103 to 5×104, respectively. The difference in the H/2B dependence of the thermal performance between the detached and attached solid-rib array is documented. H/2B=0.17 and Pi/H=10 are found to provide the best thermal performance for the range of parameters tested. Compact heat transfer and friction correlations are developed. Additionally, it is found that heat transfer augmentation with a detached solid-rib array is superior to with a detached perforated-rib array, and the mechanism responsible for the difference is revealed by the complementary flow visualization results.
Modeling the Effective Elastic Behavior of a Transversely Cracked Laminated Composite
Authors: Thomas David J. , Wetherhold Robert C.
Published: February 2015

The solution for the stress state present in the vicinity of transverse matrix cracks within a composite laminate is typically obtained by assuming a regular crack spacing geometry for the problem and applying a shear-lag analysis. In order to explore the validity of this underlying assumption, the probability density function for the location of the next transverse matrix crack within a crack bounded region is examined. The regular crack spacing assumption is shown to be reasonable from an engineering point of view. Continuing with this assumption, a generalized shear-lag model for multi-layer, off-axis laminates subjected to full in-plane loads is developed. This model is used to quantitatively evaluate the effective elastic properties of the damaged material. The results are applicable to materials such as ceramic matrix or polymer matrix unidirectional fiber systems where damage in the form of transverse matrix cracks arises.
Life-Cycle Engineering Support From the US Navy Gas Turbine Ship Complex
Authors: Socoloski Paul , Maier Michael , Lamberto Michael
Published: February 2015

The United States Navy has tested propulsion plants since the beginning of the century. There is a long record of successful test programs which have either proven new systems for introduction to the fleet or demonstrated the inability of new systems to meet the requirements of the fleet. Traditionally these test programs concluded with the introduction of the propulsion system into service. With the conception of the Gas Turbine Ship Complex in the mid 1980s, the Navy recognized the need to maintain a facility for conducting life cycle engineering activities to support the more complex gas turbine plants and control systems in the fleet. The Gas Turbine Ship Complex successfully tested the DDG-51 Class propulsion plant before the introduction of the Arleigh Burke and now continues to provide testing of gas turbine plant upgrades, allows training for DDG-51 Class precommissioning crews, enables In-Service Engineers to conduct plant operations to resolve emergent fleet problems and conducts Research and Development on new and upgraded systems.

This paper recounts the premiss for developing the Gas Turbine Ship Complex and shows how the plant has gone beyond traditional propulsion plant test programs to fulfill its mission as a facility for life cycle support of gas turbine ships.
A Comparison of HVOF and LPPS Applied MCrAlY Coating
Authors: van Esch Hans , Greaves Wayne
Published: February 2015

This study examined the ability of two High Velocity Oxyfuel (HVOF) systems, the Hobart Tafa JP 5000 and the Sulzer Metco DJ 2600 Hybrid, to apply MCrAlY coatings. The results were compared to a Low Pressure Plasma Spray (LPPS) applied material of the same chemistry. Each system is described and the optimum parameters are given. Also, an analysis of the powders is included.

The results were metallurgically evaluated for porosity level, oxygen content and yttrium distribution. Static oxidation tests were also performed on the NiCoCrAlY coating applied by each system. Conclusions were based on the relative performance of the JP 5000 and DJ 2600 Hybrid coatings as compared to the LPPS baseline material.
High Contaminant Air Filtration System for US Navy Hovercraft Gas Turbines
Authors: Ehrhardt Jerome , Piñeiro Iván
Published: February 2015

The Landing Craft Air Cushion (LCAC) is the U.S. Navy’s high speed hovercraft used for amphibious landings. The LCAC uses four Allied Signal TF40B gas turbines for propulsion and air cushion lift, and two Sundstrand T-62 gas turbines for auxiliary power. Because of the craft’s low height at sea, the air cushion pressure and the propeller thrust the LCAC generates a high volume of sea spray, dust and airborne beach sand during its amphibious mission.

For what can be considered the most severe environment of any U.S. NAVY gas turbine application, a combustion air system was designed to efficiently remove the airborne contaminants of seawater, salt and sand. This paper discusses the design, developmental testing, fleet experience and improvements for the LCAC gas turbine combustion air inlet system.
Particle Impact Tests of Ceramic Gas Turbine Materials at Room Temperature
Authors: Hara Yasushi , Makino Keisuke , Mizuno Kenichi , Shimamori Toru , Yoshida Hiro
Published: February 2015

In developing ceramic gas turbines (CGT), evaluation of impact strength of ceramic materials is one of the most important subjects. For the purpose of evaluating impact strength of ceramics, particle impact tests of ceramics are carried out at room temperature by using electrothermal (ET) gun and micro-sabot system. Power turbine nozzles and circular disk specimens made of three kinds of Si3N4 are impacted by samarium - cobalt (Sm - Co) magnet flyer particles in vacuum. Weight of particles is fixed to 4mg and particle velocities range from 300 to 900 m/sec. Thickness of specimens are 1.0, 1.5 and 2.0 mm. In this study critical impact velocity, Vc, is defined as threshold velocity which causes visible cracks on the rear surface of the impact side. The cracks seem to be brought by flexural fracture mode. It is found that Vc is related with bending strength, σ, and thickness, t, of the target material as : Vc = C · σ5/6 · t5/3. It is found that impact results with and without rear cracks are well categorized based on this empirical relationship.
Tip Leakage Flow Characteristics Downstream of an Axial Flow Fan
Authors: Puddu P.
Published: February 2015

The three-dimensional viscous flow characteristics and the complex vortex system downstream of the rotor of an industrial exial fan have been determined by an experimental investigation using hot-wire anemometer. Single-wire slanted and straight type probes have been rotated about the probe axis using a computer controlled stepper motor. Measurements have been taken at four planes behind the blade trailing edge. The results show the characteristics of the relative flow as velocity components, secondary flow and kinetic energy defect. Turbulence intensity and Reynolds stress components in the leakage vortex area are also presented. The evolution of the leakage vortex flow during the decay process has also been evaluated in terms of dimension, position and intensity.
Cold Flow Experiments in a Sub-Scale Model of the Diffuser-Combustor Section of an Industrial Gas Turbine
Authors: Kapat J. S. , Wang T. , Ryan W. R. , Diakunchak I. S. , Bannister R. L.
Published: February 2015

This paper describes the experimental facility and flow measurements in a sub-scale, 360-degree model of the diffuser-combustor section of an advanced developmental industrial gas turbine. The experiments were performed under cold flow conditions which can be scaled to actual machine operation through the use of a conventional flow parameter. Wall pressure measurements were used to calculate the static pressure recovery in the annular pre-diffuser. A five-hole probe was used to measure the complex three-dimensional flow in the dump diffuser. Mass-weighted average total pressures were calculated to examine the loss characteristics of the annular and the dump diffuser. The “sink” effect caused by the combustors induces a nonuniform velocity profile and pressure distribution at the exit of the annular pre-diffuser, thereby reducing the effectiveness of the annular pre-diffuser. The outer region of the dump diffuser effectively diffuses the flow while recirculation in other areas of the dump diffuser lowers diffuser effectiveness. Partially nonuniform flow distribution was observed at the entrance to the annular passage between the combustors and the combustor housing (top hat). The existence of circumferential flow in this annular passage tends to increase air flow uniformity into the combustor. Although a specific geometry was selected for the present study, the results provide sufficient generality for improving understanding of the complex flow behaviors in the reverse flow diffuser-combustor sections of industrial gas turbines.
Oxidation Resistance and Critical Sulfur Content of Single Crystal Superalloys
Authors: Smialek James L.
Published: February 2015

Single crystal superalloys had greatly improved cyclic oxidation resistance when their sulfur content was reduced from impurity levels, typically 5–10 ppmw in past years, down to 1 ppmw or below currently. Excellent alumina scale adhesion has been documented for PWA 1480, PWA 1484, Rene’N5, Rene’N6, and CMSX 4, all without reactive element (Y) additions. Hydrogen annealing was used for effective desulfurization to below 0.1 ppmw, as well as for achieving controlled intermediate levels. This paper summarizes the direct relationship between cyclic oxidation behavior and sulfur content. An adhesion criterion has been proposed based on the concentration of sulfur needed to initiate spallation due to a monolayer of interfacial segregation. This suggests that a level down to ∼0.2 ppmw would be needed to maximize adhesion for a 1 mm thick sample. It is in reasonable agreement with the experimental results.
GTD111 Alloy Material Study
Authors: Daleo Joseph A. , Wilson James R.
Published: February 2015

Very little property data on this common turbine blade alloy has been published. As longer hours of service are accumulated, maintenance considerations such as developing optimum component life strategies and repair processes become important. The lack of specific material data hampers the effort of users and repair facilities to achieve optimum service from this alloy.

This study measured some of the basic mechanical and metallurgical characteristics of this poly-crystalline nickel base superalloy. Tensile and short term creep rupture properties as well as microstructural and fracture characteristics are presented. Both the as-heat-treated and thermally exposed characteristics at two different temperatures are examined.
Hydrodynamics and Heat Exchange With Wall Jet Cooling of Gas Turbine Blade Internal Spaces
Authors: Soudarev A. V. , Soudarev B. V. , Medvedev N. N. , Medvedev V. V. , Soudarev V. B.
Published: February 2015

Evaluation of wall jet cooling inside of a gas turbine blade was accomplished. The wall jets are produced by confining the internal flow so that it must pass through narrow gaps and along the blade skin inner surfaces. Flow structure of the jets was revealed using polarization-optical visualization and laser Doppler anemometry. On the basis of analysis of the photos and of the flow turbulence spectra, the jet’s external boundary was identified. Diagrams of velocities, given in a non-dimensional form, for both the early development and downstream areas of the jet were obtained. Similarity solutions for local convective heat transfer to the confined wall jet were provided. The computational results agree well with the experimental data.
Thermal Strains and Their Effect on the Life of Ceramic Matrix Composite Components in Gas Turbine Engines
Authors: Percival Michael J. L. , Beesley Colin P.
Published: February 2015

Currently available Ceramic Matrix Composites (CMCs) have very low stress carrying capability if they are to achieve the service life required for application in gas turbine engines. As such, they are most likely to find their first applications in non-structural components with low mechanical loads, where the majority of the stress is thermally induced. The thermal cycling experienced in gas turbine engines, coupled with the necessary interfaces with surrounding metal components and other geometric features, means that these thermal stresses are often localised, but in order to produce a valid component design they may significantly exceed the maximum design stress.

The aim of this paper is to discuss the implications for the life of the component of these excess stresses. This will cover the mechanisms for the propagation of localised damage in a strain controlled environment, and the effect of this damage on the thermal conductivity and hence on the induced thermal gradients and thermal strains. Strains corresponding to stresses considerably above the normally accepted design stress can be sustained for a considerable number of cycles, but the influence of extended time periods with damage at elevated temperatures remains unexplored.
Efficient District Heat Production by Heat Extraction From Combined Cycle Plants
Authors: Haselbacher H. , Frutschi H. U.
Published: February 2015

Among cogeneration facilities block heating stations and large combined cycle plants are two extreme examples of district heating technologies. In this paper, these two alternatives will be applied to one and the same representative district heating task. The thermodynamic differences will be made clear and the advantages of heating by extracting steam from a combined cycle plant will become evident. An important conclusion from an engineering point of view is that extracting heat from a combined cycle plant should be considered even if this plant is located at greater distances from the heat consumers.
Economic Scales for First-Generation Biomass-Gasifier/Gas Turbine Combined Cycles Fueled From Energy Plantations
Authors: Larson Eric D. , Marrison Christopher I.
Published: February 2015

This paper assesses the scales at which commercial, first-generation biomass integrated-gasifier/gas turbine combined cycle (BIG/GTCC) technology are likely to be most economic when fueled by plantation-derived biomass. First-generation BIG/GTCC systems are likely to be commercially offered by vendors beginning around 2000 and will be based on either pressurized or atmospheric-pressure gasification. Both plant configurations are considered here, with estimates of capital and operating costs drawn from published and other sources. Prospective costs of a farm-grown energy crop (switchgrass) delivered to a power plant are developed with the aid of a geographic information system (GIS) for agricultural regions in the North Central and Southeast US in the year 2000 and 2020. A simplified approach is applied to estimate the cost of delivering chipped eucalyptus from an existing plantation in Northeast Brazil.

The “optimum” capacity (MWopt), defined as that which yields the minimum calculated cost of electricity (COEm), varies by geographic region due to differences in delivered biomass costs. With pressurized BIG/GTCC plants, MWopt is in the range of 230–320 MWs for the sites considered, assuming most of the land around the power plant is farmed for energy crop production. For atmospheric-pressure BIG/GTCC plants, MWopt ranges from 110 to 142 MWe. When a lower fraction of the land around a plant is used for energy farming, values for MWopt are smaller than these. In all cases, the cost of electricity is relatively insensitive to plant capacity over a wide range around MWopt.