bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Large Scale, High Intensity Turbulence on Vane Aerodynamic Losses, Wake Growth, and the Exit Turbulence Parameters
Authors: Ames Forrest E. , Plesniak Michael W.
Published: February 2015

An experimental research program was undertaken to examine the influence of large-scale high, intensity turbulence on vane exit losses, wake growth, and exit turbulence characteristics. The experiment was conducted in a four vane linear cascade at an exit Reynolds number of 800, 000 based on chord length and an exit Mach number of 0.27. Exit measurements were made for four inlet turbulence conditions including a low turbulence case (Tu ≈ 1%), a grid-generated turbulence case (Tu ≈ 7.5%), and two levels of large-scale turbulence generated with a mock combustor (Tu ≈ 12% & Tu ≈ 8%).

Exit total pressure surveys were taken at two locations to quantify total pressure losses. The suction surface boundary layer was also traversed to determine losses due boundary layer growth. Losses were also found in the core of the flow for the elevated turbulence cases.

The elevated free stream turbulence was found to have a significant effect on wake growth. Generally, the wakes subjected to elevated free stream turbulence were broader and had smaller peak velocity deficits. Reynolds stress profiles exhibited asymmetry in peak amplitudes about the wake centerline, which are attributable to differences in the evolution of the boundary layers on the pressure and suction surfaces of the vanes.

The overall level of turbulence and dissipation inside the wakes and in the free stream was determined to document the rotor inlet boundary conditions. This is useful information for assessing rotor heat transfer and aerodynamics. Eddy diffusivities and mixing lengths were estimated using X-wire measurements of turbulent shear stress. The free stream turbulence was found to strongly affect eddy diffusivities, and thus wake mixing. At the last measuring position, the average eddy diffusivity in the wake of the high turbulence close combustor configuration (Tu ≈ 12) was three times that of the low turbulence wake.
Modeling Tip Clearance Efects in Multi–Stage Axial Compressors
Authors: Baghdadi S.
Published: February 2015

A variety of techniques for simulating the effects of rotor tip clearances in multi–stage axial compressors is discussed. Proper recognition of stage coupling and re–matching effects is shown to be key to successful modeling of the overall behavior of actual engine compression systems. The application of a relatively simple 1–D unsteady row–by–row systems analysis is presented and shown to compare well to test data from several engine compressors.
CT Multiscan: Using Small Area Detectors to Image Large Components
Authors: Sivers E. A. , Ellingson W. A. , Snyder S. A. , Holloway D. A.
Published: February 2015

The small size and dynamic range of the best two-dimensional X-ray detectors are impediments to the use of three-dimensional X-ray computed tomography (3D-XRCT) for 100% inspection of large ceramic components. The most common industrial 3D-XRCT systems use a “rotate-only” geometry in which the X-ray source and the area detector remain stationary while the component placed between them is rotated through 360°. This configuration offers the highest inspection speed and the best utilization of X-ray dose, but requires that the component be small enough to fit within the X-ray/detector “cone.” Also, if the object is very dense, the ratio of an unattenuated X-ray signal to that through the longest path in the component may exceed the dynamic range of the detector. To some extent, both of these disadvantages can be overcome by using “Multiscan CT,” i.e., scanning small overlapping regions of a large component separately while maximizing the X-ray dose to each. The overlapping scans can then be combined seamlessly into a single scan with optimal contrast.
Navier-Stokes and Potential Calculations of Axial Spacing Effect on Vortical and Potential Disturbances and Gust Response in an Axial Compressor
Authors: Chung Meng-Hsuan , Wo Andrew M.
Published: February 2015

The effect of blade row axial spacing on vortical and potential disturbances and gust response is studied for a compressor stator/rotor configuration near design and at high loadings using 2D incompressible Navier-Stokes and potential codes, both written for multistage calculations. First, vortical and potential disturbances downstream of the isolated stator in the moving frame are defined; these disturbances exclude blade row interaction effects. Then, vortical and potential disturbances for the stator/rotor configuration are calculated for axial gaps of 10%, 20%, and 30% chord. Results show that the potential disturbance is uncoupled; the potential disturbance calculated from the isolated stator configuration is a good approximation for that from the stator/rotor configuration for all three axial gaps. The vortical disturbance depends strongly on blade row interactions. Low order modes of vortical disturbance are of substantial magnitude and decay much more slowly downstream than do those of potential disturbance. Vortical disturbance decays linearly with increasing mode except very close to the stator trailing edge. For a small axial gap, lower order modes of both vortical and potential disturbances must be included to determine the rotor gust response.
Effects of Streamwise Pressure Gradient on Turbulent Spot Development
Authors: Gostelow J. P. , Melwani N. , Walker G. J.
Published: February 2015

A pressure distribution representative of a controlled diffusion compressor blade suction surface is imposed on a flat plate. Boundary layer transition in this situation is investigated by triggering a wave packet which evolves into a turbulent spot. The development from wave packet to turbulent spot is observed and the interactions of the turbulent spot with the ongoing natural transition aad the ensuing turbulent boundary layer are examined. Under this steeply diffusing pressure distribution strong amplification of primary instabilities prevails. Breakdown to turbulence is instigated near the center line and propagates transversely along the wave packet until the turbulent region dominates. An extensive calmed region is present behind the spot which persists well into the surrounding turbulent layer. Celerities of spot leading and trailing edges are presented, as is the spanwise spreading half-angle. Corresponding measurements for spots under a wide range of imposed pressure gradients are compiled and the present results are compared with those of other authors. Resulting correlations for spot propagation parameters are provided for use in computational modeling of the transition region under variable pressure gradients.
A Computational Study of Pressure Effects on Pollutants Generation in Gas Turbine Combustors
Authors: Amin E. M. , Andrews G. E. , Pourkashnian M. , Williams A. , Yetter R. A.
Published: February 2015

A numerical study of the effect of pressure on the formation of NOx and soot in an axisymmetric 30° counter rotating axial swirler lean low NOx gas turbine combustor has been conducted. This has previously been studied experimentally and this CFD investigation was undertaken to explain the higher than expected NOx emissions. The combustion conditions selected for the present study were 300 deg K inlet air, 0.4 overall equivalence ratio, and pressures of 1 and 10 bar.

The numerical model used here involved the solution of time-averaged governing equations using an elliptic flow-field solver. The turbulence was modelled using algebraic stress modelling (ASM), The Thermo-chemical model was based on the laminar flamelet formulation. The conserved scalar/assumed pdf approach was used to model the turbulence chemistry interaction. The study was for two pressure cases at 1 and 10 bar. The turbulence-chemistry interaction is closed by assumption of a Clipped Gaussian function form for the fluctuations in the mixture fraction. The kinetic calculations were done separately from the flowfield solver using an opposed laminar diffusion flame code of SANDIA. The temperature and species profiles were made available to the computations through look-up tables.

The pollutants studied in this work were soot and NO for which three more additional transport equations are required namely; averaged soot mass fraction, averaged soot particle number density, and finally averaged NO mass fraction. Soot oxidation was modelled using molecular oxygen only and a strong influence of pressure was predicted. Pressure was shown to have a major effect on soot formation.
Development of Ceramic Composite Hot-Gas Filters
Authors: Judkins Roddie R. , Stinton David P. , Smith Robert G. , Fischer Edward M. , Eaton Joseph H. , Weaver Bill L. , Kahnke J. Lawrence , Pysher Douglas J.
Published: February 2015

A novel type of hot-gas filter based on a ceramic fiber-reinforced ceramic matrix was developed and extended to full-size, 60-mm OD by 1.5-meter-long, candle filters. A commercially viable process for producing the filters was developed, and the filters are undergoing testing and demonstration throughout the world for applications in pressurized fluidized-bed combustion (PFBC) and integrated gasification combined cycle (IGCC) plants. Development activities at Oak Ridge National Laboratory (ORNL) and at the 3M Company, and testing at the Westinghouse Science and Technology Center (STC) are presented. Demonstration tests at the Tidd PFBC are in progress. Issues identified during the testing and demonstration phases of the development are discussed. Resolution of the issues identified during testing and the status of commercialization of the filters are described.
Thermal Shock Analysis and Testing of Simulated Ceramic Components for Gas Turbine Applications
Authors: Rajiyah Harindra , Inzinna Louis P. , Trantina Gerald G. , Orenstein Robert M. , Cutrone Martin B.
Published: February 2015

A ceramic gas seal for a utility gas turbine was designed and analyzed using ANSYS and CARES/LIFE. SN-88 silicon nitride was selected as the candidate material. The objective was to validate the failure prediction methodology using rectangular plates which were thermally shocked in a fluidized bed. The failure prediction methodology would then be applied to the representative component geometry. Refined ANSYS finite element modeling of both the plate and component geometries was undertaken. The CARES/LIFE reliability analysis of the component geometry for fast fracture was performed for two cases: I) steady-state thermo-mechanical loads during normal gas turbine operation and II) transient thermal shock loading during a turbine trip. Thermal shock testing of alumina disks were performed in order to gain confidence in the testing and analysis procedures. Both notched and unnotched SN88 plates were then tested. Failure modes were identified through flexure tests and data censoring was performed using SAS. Weibull modulus was assumed to be invariant with temperature and the scale parameter was assumed to vary through a scaling variable such that multiple data could be pooled.
The Installation, Testing and Lessons Learned of the TF40B Gas Turbine Test Facility
Authors: Patterson Jeffrey S. , Harris Howard
Published: February 2015

The TF40B Gas Turbine Test Facility is the only dedicated Landing Craft, Air Cushion main propulsion engine test complex available to the U.S. Navy. This facility, located at the Naval Surface Warfare Center, Carderock Division (NSWCCD) in Philadelphia, PA, began operation in August, 1992. Since then, the test engine has logged approximately 230 starts and 350 operating hours. This paper will present the installation, testing and lessons learned of the TF40B test facility. The installation section will discuss the modifications made to the existing test facility to accept the TF40B engine. The test section will include the Foreign Object Damage (FOD) screen evaluation, both on-line and crank wash detergent fluid evaluations, cold weather fuel testing, engine vent line testing and Aerojet 5 oil evaluation. The lessons learned section will include problems related to the electric starter, waterbrake, inlet and exhaust systems, data acquisition system, instrumentation control panel and the test cell equipment arrangement.
The Development of a Combustion System for a 110 MW CAES Plant
Authors: Hounslow D. R. , Grindley W. , Loughlin R. M. , Daly J.
Published: February 2015

The use of stored energy systems is receiving increased attention for power generation and Alabama Electric Co-operative (AEC) have installed a 110 MW Compressed Air Energy Storage (CAES) plant at McIntosh, Alabama.

The plant employs tandem high and low pressure fired expanders with the high pressure combustors operating at 44 atm and the low pressure units at 15 atm. Both are designed to operate with natural gas, or on No. 2 fuel oil, as a standby fuel.

This paper describes the development of both the high and low pressure combustors for this unique application, the testing of prototypes at simulated conditions at up to 8 atm using customised test rigs and the definition of a design for application to the plant.

Problems encountered during the first three years of operation are described and the solutions to overcome these are also presented.
Optimization of Multiple Jets Mixing With a Confined Crossflow
Authors: Doerr Th. , Blomeyer M. , Hennecke D. K.
Published: February 2015

An experimental investigation of a non-reacting multiple jet mixing with a confined crossflow has been conducted. Flow and geometric conditions were varied in order to examine favourable parameters for mixing. The requirement for a rapid and intense mixing process originates from combustion applications, especially the RQL-combustion concept. Thus, the jets were perpendicularly injected out of one opposed row of circular orifices into a heated crossflow in a rectangular duct. Spacing and hole size were varied within the ranges referring to combustor applications. The results presented are restricted to an inline orientation of opposed jet axis. Temperature distribution, mixing rate and standard deviation were determined at discrete downstream locations. Best i.e. uniform mixing can be observed strongly depending on momentum flux ratio. For all geometries investigated an optimum momentum flux ratio yields to a homogeneous temperature distribution in the flowfield downstream of the injection plane. Too high ratios deteriorate the mixing process due to the mutual impact of the opposed entraining jets along with a thermal stratification of the flowfield. Correlations are introduced describing the dependency of optimum momentum flux ratio on mixing hole geometry. They allow the optimization of jet-in-crossflow mixing processes in respect to uniform mixing.
Fatigue Cracking in Fiber-Reinforced Metal Matrix Composites Under Mechanical and Thermal Loads
Authors: Bao G. , McMeeking R. M.
Published: February 2015

This article reviews micromechanical models developed for fatigue cracking in fiber reinforced metal matrix composites under mechanical and thermal loads. Emphases is placed on the formulae and design charts that can quantify the fatigue crack growth and fiber fracture. The composite is taken to be linear elastic, with unidirectional aligned fibers. Interfacial debonding is assumed to occur readily, allowing fibers to slide relative to the matrix resisted by a uniform shear stress. The fibers therefore bridge any matrix crack which develops. The crack bridging traction law includes the effect of thermal expansion mismatch between the fiber and the matrix and a temperature dependence of the frictional shear stress. Predictions are made of the crack tip stress intensities, matrix fatigue crack growth and maximum fiber stresses under mechanical or thermomechanical loads. For composites under thermomechanical load, both in-phase and out-of-phase fatigue are modeled. The implications for life prediction for fiber reinforced metal matrix composites are discussed.
A Code for Thermal Analysis of STIG Turbines
Authors: Bartolini Carlo M. , Salvi Danilo , Pennacchioli Marcello
Published: February 2015

A computer model to evaluate the off-design performance of steam injection gas turbines (STIG) has been developed; the code utilizes turbine and compressor curves, and requires only one operation point as further input parameter. The global thermal analysis has been performed by means of the iterative solution of a non-linear equations system.

The model is based on the following hypothesis: air convection/film cooling process and turbine choking condition.

The prediction of air cooling flow has been correlated to the air temperature, function of the compressor efficiency and the bleed point pressure and to the gas temperature, directly related to the work output. The thermal exchange between blades and hot gas has been computed by means of a model proposed in literature.

The code is a handy tool to predict the off-design performance of STIG plants, also it can simulate the analysis of existing plants in order to evaluate the feasibility of some implementations.

An interesting analysis of the performance of a real STIG plant has been carried out and the comparison between the calculated and the experimental curves validates the computational procedure.
Technical/Economic Analysis of an Integrated System for Sludge Dehydration and Electric Power Generation Applying Gas Turbine Cycles
Authors: Ghezzi Umberto , Pasini Silvano
Published: February 2015

The problem of sludge dehydration assumes an ever growing importance, owing also to the constant increasing diffusion of water treatment plants. To better understand the entity of the problem it is enough to pay attention to the fact that water treatment plants can produce up to hundreds of tons per day of sludges, whose disposal is of not less importance if compared to the treatment of liquid effluents.
LM-2500 First Stage Filtration Upgrades
Authors: Johnson Steven R. , Thomas David A.
Published: February 2015

This paper addresses problems and solutions associated with the first stage inlet air treatment systems provided with six General Electric (GE) LM-2500 PE aeroderivative gas turbines used in a Combined Cycle Cogeneration application. The LM-2500’s are sited adjacent to gypsum wallboard plants, which serve as the Cogeneration hosts.

Problems associated with the inlet air treatment systems were noted soon after start-up of the LM-2500 engines in June 1992 and February 1993. Poor performance of the air treatment system appeared to contribute to premature failures in the Gas Turbine hot sections. Heavy particulate loading due to the surrounding gypsum environment was identified as the root cause of the problems affecting the first and second filtration stages and the evaporative cooling stage of the engine inlet air systems.

Following air sampling tests, a number of modifications and upgrades were studied to improve the performance of the inlet air treatment. An engine inlet at each site was modified with a bag filter system for the first stage filtration. The performance of the modified inlets was then monitored and compared to the remaining units. After the successful performance of the modified inlets during the second and third quarters of 1994, the remaining LM-2500 engine inlets were subsequently modified in October 1994.
Numerical Analysis of Intra-Cavity and Power-Stream Flow Interaction in Multiple Gas-Turbine Disk-Cavities
Authors: Athavale M. M. , Przekwas A. J. , Hendricks R. C. , Steinetz B. M.
Published: February 2015

A numerical analysis methodology and solutions of the interaction between the power stream and multiply-connected multi-cavity sealed secondary flow fields are presented. Flow solutions for a multi-cavity experimental rig were computed and compared with experimental data of Daniels and Johnson. The flow solutions illustrate the complex coupling between the main-path and the cavity flows as well as outline the flow thread that exists throughout the subplatform multiple cavities and seals. The analysis also shows that the de-coupled solutions on single cavities is inadequate. The present results show trends similar to the T-700 engine data that suggests the changes in the CDP seal altered the flow fields throughout the engine and affected the engine performance.
Numerical Transonic Flow Field Predictions for NASA Compressor Rotor 37
Authors: Dalbert Peter , Wiss Donald H.
Published: February 2015

Flow field calculations of the NASA transonic axial compressor Rotor 37 are presented. These were obtained by the two commercially available 3D Navier Stokes-codes BTOB3D and TASCflow using different turbulence models, i.e. Baldwin-Lomax and k-ε. Some of the results were submitted to the CFD code assessment exercise organized in 1994 by the Turbomachinery Committee of the ASME, where a number of “blind” CFD predictions were compared against previously unknown experimental data taken at the NASA Lewis Research Center.

The objective of these calculations was to use the codes in the same way as they are generally used by experienced engineers for standard industrial design tasks. Thus, the effort involved in grid generation, flow simulation runs and postprocessing was subject to the usual limitations in computer resources as well as a stringent observation of cost-effectiveness (manpower and time available).

With both codes, two sets of calculations were carried out: BTOB3D with two different tip clearances and TASCflow with a uniform and a spanwise varying outlet static pressure. Generally, the results of both codes show good agreement with respect to the measured overall performance characteristics and averaged spanwise distributions. In particular, the TASCflow solutions display high prediction accuracy in some local details of the flow field while in the BTOB3D code, boundary effects seem to mix out the flow significantly.

The solution strategies employed as well as the reasons for certain discrepancies between computations and measurements are discussed.
Hot Gas Particulate Cleanup for Advanced Coal-Based Power Systems
Authors: Dennis Richard A. , McDaniel Heather M. , McMahon Theodore J.
Published: February 2015

Integrated Gasification Combined Cycle and Pressurized Fluidized-Bed Combustion power systems have made it possible to use coal while still protecting the environment. Such power systems virtually eliminate the pollutants associated with coal-fired plants built before the 1970’s. Superior environmental performance and high system efficiency requires that gas stream cleanup be conducted under high temperature and high pressure process conditions. To realize this high system efficiency, particulate cleanup levels must meet gas turbine particulate tolerance limits. Discussed below are some of the particulate cleanup requirements and challenges for these advanced power systems. Also presented is the work underway to support particulate cleanup technology and the Clean Coal Technology (CCT) Program through pilot-scale testing and filter component development.
Lean Premixing Prevaporizing Fuel Injectors Comparison
Authors: Trichet P. , Bismes F.
Published: February 2015

This paper presents detailed experimental results of a vaporizing spray produced by two atomizers in a coflowing air stream inside a constant section lean premixer prevaporizer tube. This study is part of an ongoing effort to understand the behavior of spray under a variety of conditions. PDPA was used to characterize the atomization and vaporization process. The evolution of the two phase flow at each section was assessed in terms of global spray behavior and spray dynamics. The results confirm the influence of fuel injector on size distribution also the relative velocity between gas and dispersed phase on secondary atomization, and finally the complex spray structure in terms of wall proximity.
Shroud Influence on Gas Turbine Airblast Atomizer Swirler Flowfields
Authors: Micklow Gerald J. , Shivaraman Karthikeyan , Cho Insoo
Published: February 2015

The performance of high shear airblast fuel injectors for advanced gas turbine combustors is highly dependent on the design of the swirl vanes. The vanes may be of the straight or curved type. Curved vanes usually exhibit lower losses but straight vanes are also used due to lower cost and ease of manufacture. These type of vanes often operate under highly stalled conditions with high total pressure loss and a highly non-uniform exit velocity profile. This may produce poor fuel atomization with a non-uniform combustor fuel distribution resulting in lowered combustor efficiency and increased pollutant emissions.

Constant turning curved vanes can also be easily manufactured. Properly designed vanes result in a greatly reduced total pressure loss. The exit velocity distribution is more uniform and higher in magnitude which can result in improved fuel atomization and distribution in the combustor. Further, the presence of a shroud is seen to have a major effect on the downstream flowfield.

The present study compares standard helical flat vane performance with a low loss curved vane designed by the author for idle, and cruise conditions both with and without a shroud. The results from a three dimensional viscous numerical flow simulation show the curved swirl vane to be clearly superior to the standard flat helical swirl vane. The curved vane has a much lower total pressure loss with a more uniform exit velocity profile. This may result in improved combustor and engine performance and reduced pollutant emissions.

The effect of the shroud was seen to reduce the size of the stall cell found in the vane passage for the helical vane. This resulted in a decrease in the magnitude of the axial velocity component in the outer vane passage and a decrease in the circumferential velocity component. This may result in a decrease in the swirl number. For the curved vane however, an increase in the magnitude of all velocity components was found which will result in a higher swirl number and better nozzle performance.
Comparative Evaluation of the Effect of Turbine Configuration on the Performance of Heavy-Duty Gas Turbines
Authors: Kim Tong Seop , Ro Sung Tack
Published: February 2015

Performance of the heavy-duty gas turbine is analyzed with a special focus on the effect of turbine configuration. A general program is developed to fully represent the real component features by the characteristic models. The program is applied to simulate the performance of current heavy-duty gas turbines and its appropriateness for system analysis is verified. Meanwhile, the component parameters of real engines which describe the technology level are obtained. The effect of turbine parameters on the overall gas turbine performance is comparatively evaluated. A special emphasis is put on the analysis of the effect of number of turbine stages on the gas turbine performance and maximum power. Definite performance discrepancy due to the difference in the number of turbine stages is presented. It is found that number of turbine stages considerably affects the maximum gas flow and thermodynamic performance enhancement of the high-temperature advanced gas turbine is meaningful only when the mechanical constraint is relaxed.
Prediction of Combustion Induced Oscillations Using a Pressure-Correction Method
Authors: Liu Ren , McGuirk James J.
Published: February 2015

The objective of the present paper is to describe the development and testing of a CFD method based on a pressure-correction formulation for the prediction of reheat-buzz-type combustion induced oscillations. A quasi-1D approach was adopted to describe the acoustic phenomena occurring in a typical premixed flame stabilised on a conical gutter. Experimentally deduced unsteady heat release data available in the published literature were used to drive the calculations. Excellent agreement was observed between measured and predicted mode shapes and phase distributions of the unsteady pressure field. Calculations also indicated that the measured buzz frequencies could be reasonably well predicted.
Spatially-Resolved Soot Measurements in Gas Turbine Combustors
Authors: Zheng Q.-P. , Stewart C. D. , Moss J. B.
Published: February 2015

The difficulties in making spatially-resolved measurements of soot concentration inside practical combustors, which do not rely on sample extraction techniques, are highlighted. Restricted optical access presents the principal constraint to the adoption of established tomographic techniques. A novel hybrid approach, which combines a traversable laser shielding tube and conventional integrated absorption measurement, is demonstrated in two tubular combustors operating at a range of AFRs, inlet air temperatures and pressures. Measurements are reported which have been taken through existing primary and dilution ports and through additional line-of-sight holes drilled in the liner specifically for that purpose. Distinctive radial profiles of soot volume fraction emerge, reflecting the annular development of richer mixtures, which favour soot formation, downstream of the fuel injector.
Axisymmetric Aerodynamic Numerical Analysis of a Turbofan Engine
Authors: Stewart Mark E. M.
Published: February 2015

An equation and numerical solution procedure for a steady-state aerodynamic analysis of a turbofan engine in the meridional plane is presented. An axisymmetric average of the three-dimensional fluid flow equations within the engine is presented. The equations simultaneously represent the major engine components and include terms for blade forces, loss, combustor heat addition, blockage, bleeds and convective mixing in the mixer. These general equations are specialized with modeled terms and advanced to a steady-state with a time-marching scheme on a multi-block grid. The procedure is verified with comparisons to one-dimensional analytic solutions and a compressor stage. How this procedure can capture component interactions is demonstrated with a solution for General Electric’s Energy Efficient engine, which is representative of modern turbofan engines.
High Speed Civil Transport Propulsion Installation Issues
Authors: Gilkey S. C. , Hines R. H. , Shaw R. J.
Published: February 2015

The integration of the propulsion system with the airframe is critical to the success of the High Speed Civil Transport (HSCT), a second generation supersonic civil transport aircraft. The installation of the propulsion system directly impacts the overall aircraft system aerodynamic performance and noise. This is especially true for a supersonic aircraft where the performance of the inlet and exhaust nozzle is more important to the aircraft than the performance of the turbomachinery. Careful consideration of potential safety issues, maintenance practices, and operational requirements, including the split of supersonic and subsonic flight, must be accounted for when establishing the installation approach. The installation design philosophy has a major impact on the propulsion and aircraft system weight, and consequently, the overall economic viability of the aircraft.
Measurement and Visualization of Three-Dimensional Flows in a Linear Turbine Cascade
Authors: Yamamoto Atsumasa , Kaba Katsuyoshi , Matsunuma Takayuki
Published: February 2015

To know the internal flows and the loss generation mechanisms in turbine blade passages, three–dimensional flows in a linear turbine cascade were measured in detail using a five–hole Pitot tube. Flow visualization tests were also carried out with oil smoke to see the unsteady behavior of the internal flows. The flow visualization tests show generation of various vortices occurring inside the cascade passage, which were hardly detectable with steady flow measurement. Many of the vortices behave unsteadily. The evolution of two legs of the leading edge horseshoe vortex was clearly visualized as a combined vortex system. Low energy fluids inside the boundary layer on the blade suction surface were seen to circulate very slowly and were fairly unstable. Rotational directions of the low energy fluids depend on the interaction with the surrounding vortex system. Many separated and strong reverse flows were also seen near the blade trailing edge.
Unsteady Pressure Measurement in a High Temperature Environment Using Water Cooled Fast Response Pressure Transducers
Authors: Ferguson D. G. , Ivey P. C.
Published: February 2015

Measurement of unsteady pressure is a requirement in many proposed aero-engine active control systems. In the high temperature environment associated with the engine, thermally unprotected transducers may not measure accurately or even survive. This paper reports an examination of two water cooled, commercially available unsteady pressure transducers, which assesses the ability of the transducer to accurately measure unsteady pressure when mounted in a water cooling adapter and the effectiveness of the thermal protection at high temperatures.

Mounting the transducer in a cooling adapter was shown to have no adverse effect upon its ability to measure dynamic pressure. Deliberately recessing the adapter back from the flow provided the most stable and predictable output at all flow conditions tested. Thermal protection allowed the transducer to survive at flow temperatures of up to 500°C with a potential to survive at higher temperatures. No reduction in performance is shown at elevated temperatures relative to performance at ambient conditions.
Gas Temperature Measurement in the Hot Section of Turbine Engines
Authors: Tregay George W. , Calabrese Paul R. , Finney Mark J. , Stukey Kevin B.
Published: February 2015

An optical sensor system extends gas temperature measurement capability in turbine engines beyond the present generation of sensor hardware for production engines. The sensing element incorporates a thermally emissive insert to generate an optical signal proportional to the gas temperature at the tip of the probe. The use of a sapphire lightguide allows operation above the melting point of nickel based alloys.

Sensor development for aircraft turbines has included flight hardware for use on the Fiber Optic Control System Integration (FOCSI) Program sponsored by NASA Lewis Research Center. The optical probe harness measured exhaust gas temperatures in a General Electric F404 engine. Signals from four probes were optically combined at a single detector assembly to determine the average gas temperature. A comparison of optical and thermocouple temperature measurements was conducted during a preflight engine test.

The durability of the probe design has been evaluated in an electric-utility operated gas turbine under the sponsorship of the Electric Power Research Institute. The temperature probe was installed between the first stage rotor and second stage nozzle on a General Electric MS 7001B turbine at Houston Lighting and Power Company. Two probes have been used in the field test and they have a combined total of 4660 hours of operation near 1600°F and 330 starts.
Dynamic Model of a Two Shaft Heavy-Duty Gas Turbine With Variable Geometry
Authors: Nava Pierluigi , Quercioli Valter , Mammoli Tiziano
Published: February 2015

When designing a new plant, often it is necessary to make a simulation of the process in order to evaluate the dynamic behaviour of the whole system and the need of changes for its optimal performance. So dynamic models of the gas turbines used in the plant, either as mechanical drives or power generation, are needed. Actual gas turbines often incorporate variable geometry both in cold and hot sections. For example, the last generation of axial compressors are often equipped with variable geometry stator blades in order to achieve stable operation within the whole operating range, from start-up to full speed. As another example, power turbines sometimes have inlet guide vanes with a variable geometry in order to get a better efficiency at both partial load and speed, allowing the gas generator to run at the design speed. Disregarding to this, dynamic models which can be found in the actual literature deal with hot sections having a fixed geometry. This paper presents a dynamic model of two shaft heavy-duty gas turbines, with variable geometry in either cold and hot sections. It can be used to evaluate all the transient conditions such as start-up, shut-down and load variations in the normal operating range.
Validation of a Stochastic Fuel Injection Model for Gas Turbine Combustors
Authors: Micklow Gerald J. , Cho Insoo
Published: February 2015

In gas turbine combustors, enhanced atomization through the whole combustor region is essential for satisfactory performance since droplet size and distribution can have direct impact on almost all key aspects of combustion. To predict these flows, KIVA-II, a three-dimensional full Reynolds-averaged Navier-Stokes solver with the capability to handle finite rate chemistry and liquid spray injection is utilized. The Monte-Carlo based spray model in KIVA-II was developed to predict the flows in internal combustion engines and includes submodels for drop injection, breakup, coalescence, and evaporation. To assess the validity of the spray model for gas turbine combustors, numerical flow field predictions have been compared with experimental data provided by University of California, Irvine (UCI) Combustion Laboratory. The predicted spray behavior is in satisfactory agreement between the numerical prediction and the experiment downstream near the fuel injector. However, far downstream of the nozzle exit the deviation between the numerical results and the experimental data increases.
Flow Analysis of High Pressure Catalytic Combustor for Gas Turbine
Authors: Tsujikawa Y. , Fujii S. , Sadamori H. , Ito S. , Katsura S.
Published: February 2015

The objective of this paper is modeling the mechanism of high temperature catalytic oxidation of natural gas, or methane. The model is two-dimensional steady-state, and includes axial and radial convection and diffusion of mass, momentum and energy, as well as homogeneous (gas phase) and heterogeneous (gas-surface) single step irreversible chemical reactions within a catalyst channel.

Experimental investigations were also made of natural gas, or methane combustion in the presence of Mn-substituted hexaaluminate catalysts. Axial profiles of catalyst wall temperature, and gas temperature and gas composition for a range of gas turbine combustor operating conditions have been obtained for comparison with and development of a computer model of catalytic combustion.

Numerical calculation results for low pressure agree well with experimental data. The calculations have been extended for high pressure (10 atms) operating conditions of gas turbine.
The TF40B Component Improvement Program
Authors: House Edward M. , Rubenstein Howard D.
Published: February 2015

The AlliedSignal TF40B engine is currently used on the U.S. Navy’s Landing Craft Air Cushion (LCAC) vehicle for main propulsion. The purpose of the TF40B Component Improvement Program (CIP) is to improve the engine’s performance, enhance reliability and reduce maintenance actions. This program has addressed areas of concern by selecting compressor coatings, improving main bearing seal performance, improving hot section coatings and improving combustor liner performance. This paper will review the progress to date of the CIP tasks with particular emphasis on the combustor liner modifications.
Certification of Gas Turbine Propulsion Units for High Speed Light Craft
Authors: Waldhelm Chris , Bertsch Jim
Published: February 2015

The drive to produce lighter, faster vessels has been increasing the market interest in marine gas turbine propulsion systems. Classification Rules for propulsion systems in vessels require certification. Classification Rules cover many aspects of design philosophies. For new, high speed and light craft designs, gas turbine power is being optimized to economically blend higher vessel speeds, lower operating costs, and improved payloads. As part of this process, a concurrent design effort involving class societies is highly recommended to speed certification and increase the project’s experience pool.

Classification Societies, as independent third parties, issue standards (rules) for safe design, construction, and operation of ships. Certification is used to document compliance with the standards or rules. The certification process is usually based on design reviews and witnessing of manufacturing and testing.

Recently, a project at Solar Turbines Incorporated required a pair of 5 MW marine gas turbines propulsion units to be certified by Det Norske Veritas Classification AS. The gas turbines drive waterjets for a 45 meter, 332 passenger, 47 knot vessel designed and manufactured by FBM Marine Limited in the United Kingdom.
The Application of Thin Film Gauges on Flexible Plastic Substrates to the Gas Turbine Situation
Authors: Guo S. M. , Spencer M. C. , Lock G. D. , Jones T. V. , Harvey N. W.
Published: February 2015

Thin film heat transfer gauges have been instrumented onto flexible plastic substrates which can be adhesively bonded to plastic or metal models. These new gauges employ standard analysis techniques to yield the heat flux to the model surface and have significant advantages over gauges fired onto machinable glass or those used with metal models coated with enamel. The main advantage is that the construction of the gauges is predictable and uniform, and thus calibration for thickness and geometric properties is not required.

The new gauges have been used to measure the heat transfer to an annular turbine nozzle guide vane in the Oxford University Cold Heat Transfer Tunnel. Engine-representative Mach and Reynolds numbers were employed and the free-stream turbulence intensity at NGV inlet was 13%.

The vanes were either precooled or preheated to create a range of different thermal boundary conditions. The gauges were mounted on both perspex and aluminium NGVs and the heat transfer coefficient was obtained from the surface temperature history using either a single layer analysis (for perspex) or double layer (for aluminium) analysis. The surface temperature and heat transfer levels were also measured using rough and polished liquid crystals under similar conditions. The measurements have been compared with computational predictions.
High Temperature Degradation of Coating and Substrate in Gas Turbine Blade
Authors: Sugita Y. , Ito M. , Isobe N. , Sakurai S. , Gold C. R. , Bloomer T. E. , Kameda J.
Published: February 2015

This paper studied high temperature degradation behavior of gas turbine blades consisting of CoNiCrAlY coatings and Rene 80 substrates using a small punch (SP) testing technique at 295–1223 K and scanning Auger microprobe (SAM). In SP tests, coating cracks continuously propagated along the radial direction at 295 K and many cracks discretely were formed along more random directions at higher temperatures. The ductility of the coating at 295 K was reduced and the ductile-brittle transition temperature was increased during long time exposure of gas turbine blades to high temperature oxidation environments. SAM analyses on cross sections and fracture surfaces of the coatings indicated that oxidation and S segregation near the coating surface are profoundly induced in-service. The relationship between the mechanical properties and microstructural/chemical evolution near the coating surface is presented which serves as a data base for determining the remaining life of gas turbine blades.
Evaluation of High Pressure Turbine Blade Coatings on an LM2500 Rainbow Rotor
Authors: Nagaraj B. , Katz G. , Maricocchi A. F. , Rosenzweig M.
Published: February 2015

Two LM2500 rainbow rotors with repaired stage 1 and stage 2 high pressure turbine blades are being assembled for marine propulsion service evaluation by the US Navy. The blades have seen between 5,000 and 15,000 hours of service in the Navy’s Fleets. A number of corrosion resistant coatings including plasma sprayed CoCrAlHf (bill of material), composite plated CoCrAlHf, platinum aluminide, aluminum silicide, and physical vapor deposited yttria stabilized zirconia thermal barrier coating (PVD TBC) will be evaluated in the rainbow rotor. This paper will discuss the advantages and microstructures of the various coatings.

Composite plated CoCrAlHf, and PVD TBCs were recently service evaluated in an industrial LM2500 rainbow rotor for 10,500 hours. Both these coatings performed well, although the PVD TBC had local spallation at the leading edge. This paper will review the details of performance of these two coatings in the industrial LM2500 application.
The Design and Initial Development of a Combustion System for the WR-21 Intercooled Recuperated Gas Turbine
Authors: North Richard P. , Dawson Roger E.
Published: February 2015

This paper presents the design and initial development of a conventional combustion system to meet the specific requirements of an Intercooled Recuperated (ICR) Gas Turbine for Marine Propulsion use.

The ICR cycle offers considerable benefit in terms of fuel consumption over a wide power range, however, it presents the combustion designer with unique requirements including, but not limited to, air-to-fuel ratio (AFR) operating range, combustor inlet temperature range and combustion aerodynamics, whilst achieving acceptable combustion parameters such as ignition envelope, exit temperature traverse, smoke and emissions, component durability and integrity. The design and development of solutions to these challenges considered and chosen for the WR-21 are discussed, and results of early rig and engine testing outlined.
Synchronous Rotor Vibration Driven by Fluid Forces From a Geometrically Imperfect Labyrinth Seal
Authors: Millsaps Knox T. , Williston William C.
Published: February 2015

The radial force acting on a rotor, due to an asymmetric pressure distribution inside the seal gland, generated from a slightly non-circular single gland labyrinth seal rotating inside a circular outer casing is investigated theoretically. A fluid mechanical lumped parameter model for the flow in and out of the seal as well as the flow around the gland in the seal is developed. The model includes first and second knife imperfections as well as rotating gland depth variations. Knife non-circularity on the rotor may be due to manufacturing tolerances or defects from in service wear damage. An appropriate solution technique for the coupled one-dimensional equations is presented. Results from this model are presented that indicate these fluid induced forces are comparable in magnitude to those generated by a rotating unbalance under some conditions. Considerations for design are given for avoiding synchronous vibration problems due to non-circular labyrinth seals.
Effect of Machining and Shot Peening on the Residual Stresses of Superalloy Turbine Discs
Authors: Taricco Federica
Published: February 2015

It is well known that the field of residual stresses in the surface layer of a component greatly influences its fatigue behavior. The distribution of stresses is created by processes like welding, machining, thermal treatments.

The object of the present study was to correlate the effect of operations like turning, broaching and shot peening with the residual stresses of a highly–stressed flight safety component like a turbine disc made in Inconel 718 superalloy.

The residual stress distributions were measured with newly installed x–ray diffraction equipment, in which real engine components can be tested.

Different machining parameters and tools were used, and other factors like deformations during processing and thermal conditions of the disc in service were taken into account.

The final aim of the activity was to perform a manufacturing cycle which can minimize production costs and, at the same time, guarantee the highest possible quality level required in such a critical component.