bluuebunny/crossref_metadata_2025 huggingface dataset:
Semi-Closed Gas Turbine/Combined Cycle With Water Recovery and Extensive Exhaust Gas Recirculation
Authors: Facchini Bruno , Fiaschi Daniele , Manfrida Giampaolo
Published: February 2015

This innovative gas turbine cycle can offer several advantages over conventional cycles from the point of view of environmental friendship. The basic idea of SCGT/CC (Semi-Closed Gas Turbine/Combined Cycle with water recovery) is to cool down the exhaust temperatures to allow full condensation of the water vapor, and recirculate a large part of the exhaust gases to the compressor. The condensed water can then be reinjected by means of a pump at compressor delivery. The working gas composition is thus close to that corresponding to stoichiometric combustion, which opens the possibility of applying techniques for CO2 recycling and general exhaust gas treatment. An increase in work output is connected to water injection, while a high level of efficiency is maintained as the compressor work is reduced and the cycle parameters are tuned for the exhaust of this turbine.
Magnetic Bearing Improvement Program at NOVA
Authors: Alves Paul S. , Alavi Barry M.
Published: February 2015

Nova Gas Transmission Ltd., located in Alberta, Canada, has lead the way in the application of dry gas seals and magnetic bearings to centrifugal compressors in gas pipeline service. The introduction of magnetic bearings in the NGTL system started in 1986 and to date some 34 units were installed. There are presently 31 units running with magnetic bearings due to some units being retired.

It was part of NGTL vision to pursue the application of technologies holding promise of increased efficiencies for the pipeline. The installation of units with magnetic bearings had coincided with a period of rapid expansion of the pipeline in which there were limited resources and time available to assess equipment performance. Well into the magnetic bearing program, challenges associated with the magnetic bearing systems started to accumulate to a point where a serious study was warranted. These were in essence, the incidence of unit shutdowns, failure of components, and ultimately some instances of internal rubs of the rotating elements of the compressors.

A complete technical audit of the magnetic bearing installed base at NGTL was conducted to evaluate potential improvements to the system, improve the knowledge of NGTL personnel in the relevant technical aspects, and set the foundation for on-going management of the technology.

This audit effort pointed out several areas for improvement and a number of remedies were selected for implementation; mostly changes in the control system design, auxiliary bearing layout, and quality control of the installation.

The changes proposed have been implemented in 18 units during 1995, with some other 6 planned for 1996. The results were excellent with the reliability of the upgraded units reaching virtually 100%. It should be pointed out that these 18 units have now accumulated 22,000 hours in service throughout the year.

The most important part of this program is however, the Quality Control of the installations. We can say most of our problems in the past could certainly be attributed to poor quality control and should not be seen as an indictment of the magnetic bearings.

There is optimism about the magnetic bearing performance and the long term benefits of using this technology.
Steady-State and Time-Dependent Experimental Results of a NACA-3506 Cascade in an Annular Channel
Authors: Körbächer Heiko , Bölcs Albin
Published: February 2015

An experimental investigation of the steady-state and time-dependent aerodynamic behaviour of a compressor cascade in a ring channel was conducted at the Laboratoire de thermique appliquée et de turbomachines (LTT) at the Swiss Federal Institute of Technology in Lausanne. The cascade consisted of 20 blades with a NACA-3506 profile, stagger angle of 40°, and solidity of 0.72 at midspan. Measurements were done for a number of incidence angles over a small range of inlet Mach numbers between ∼0.75 and ∼0.8 in order to examine the influence of an increasing angle of attack on the steady-state and time-dependent pressures. As the angle of attack increased a growing corner stall was observed at the hub and a supersonic zone appeared at the leading edge.

The cascade was vibrated in bending mode with a constant amplitude at a reduced frequency of ∼0.42 at imposed interblade phase angles ranging from 0° to 324°, but also with each blade vibrating in a single blade vibration mode. The unsteady data showed that the cascade was in general damped with the minimum damping between ∼−36° to ∼+36° interblade phase angle for all examined incidence angles. The influence coefficient technique was used to identify the damping influence of each of the blades on itself (eigeninfluence) and of blades up and down the cascade (positive- and negative-sided) for different inlet incidence angles.
Oscillating Cascade Aerodynamics at Large Mean Incidence
Authors: Buffum Daniel H. , Capece Vincent R. , King Aaron J. , El-Aini Yehia M.
Published: February 2015

The aerodynamics of a cascade of airfoils oscillating in torsion about the midchord is investigated experimentally at a large mean incidence angle and, for reference, at a low mean incidence angle. The airfoil section is representative of a modern, low aspect ratio, fan blade tip section. Time-dependent airfoil surface pressure measurements were made for reduced frequencies of up to 1.2 for out-of-phase oscillations at a Mach number of 0.5 and chordal incidence angles of 0° and 10°; the Reynolds number was 0.9×106. For the 10° chordal incidence angle, a separation bubble formed at the leading edge of the suction surface. The separated flow field was found to have a dramatic effect on the chordwise distribution of the unsteady pressure. In this region, substantial deviations from the attached flow data were found with the deviations becoming less apparent in the aft region of the airfoil for all reduced frequencies. In particular, near the leading edge the separated flow had a strong destabilizing influence while the attached flow had a strong stabilizing influence.
Validation of a Nonlinear Unsteady Aerodynamic Simulator for Vibrating Blade Rows
Authors: Ayer Timothy C. , Verdon Joseph M.
Published: February 2015

A time-accurate Euler/Navier-Stokes analysis is applied to predict unsteady subsonic and transonic flows through a vibrating cascade. The intent is to validate this nonlinear analysis along with an existing linearized inviscid analysis via result comparisons for unsteady flows that are representative of those associated with blade flutter. The time-accurate analysis has also been applied to determine the relative importance of nonlinear and viscous effects on blade response. The subsonic results reveal a close agreement between inviscid and viscous unsteady blade loadings. Also, the unsteady surface pressure responses are essentially linear, and predicted quite accurately using a linearized inviscid analysis. For unsteady transonic flows, shocks and their motions cause significant nonlinear contributions to the local unsteady response. Viscous displacement effects tend to diminish shock strength and impulsive unsteady shock loads. For both subsonic and transonic flows, the energy transfer between the fluid and the structure is essentially captured by the first-harmonic component of the nonlinear unsteady solutions, but in transonic flows, the nonlinear first-harmonic and the linearized inviscid responses differ significantly in the vicinity of shocks.
Ceramic Matrix Composites Application in Automotive Gas Turbines
Authors: Kaya Hiroshi , Izumi Takao
Published: February 2015

We are conducting the development of ceramic matrix composites (CMC) and components made of CMC for a 100 kW automotive ceramic gas turbine (CGT) as shown in Fig.1. When compared to monolithic ceramics (MC), CMC that we have developed demonstrate superior strength characteristics in terms of resistance to particle impact and thermal shock. We have conducted evaluation tests on the strength of CMC components in which MC such as silicon nitride and silicon carbide were used as a reference for comparison with CMC in the same testing process as employed for components made of MC such as silicon nitride and silicon carbide. It was confirmed that actual components made of CMC realized approximately the same strength as the test pieces. Furthermore, some CMC components have already passed screening tests that evaluated the strength of the components. It was therefore confirmed that the potential exists for the possibility of testing these components in high temperature assembly tests and engine tests.
Capacitive Measurement of Compressor and Turbine Blade Tip to Casing Running Clearance
Authors: Müller D. , Sheard A. G. , Mozumdar S. , Johann E.
Published: February 2015

It is an established fact that the efficiency of a gas turbine engine has an inverse relationship with the clearance between the rotor blades and the casing (Tip Clearance, or TC). TC is an essential measurement during the testing of development engines. While commercial TC measurement systems are available, their applicability to an engine is dictated by engine size, geometry, physical accessibility and temperature distribution around the measurement region.

This paper describes the development of a TC measurement system, based on the capacitive measurement principle, which was undertaken to satisfy the application requirements of a specific class of gas turbine engines. The requirements included a relatively long and flexible cable to route the electrical signals out of the engine. The TC measurement system was successfully used during engine testing and valuable data were obtained.
Measurements of Heat Transfer Coefficients and Friction Factors in Passages Rib-Roughened on All Walls
Authors: Taslim M. E. , Li T. , Spring S. D.
Published: February 2015

A liquid crystal technique was used to measure heat transfer coefficients in twelve test sections with square and trapezoidal cross-sectional areas representing blade midchord cooling cavities in a modern gas turbine. Full-length ribs were configured on suction side as well as pressure side walls while half-length ribs were mounted on partition walls between adjacent cooling cavities. Ribs were in staggered arrangements with a nominal blockage ratio of 22% and an angle of attack to the mainstream flow, α, of 90°. Heat transfer measurements were performed on the roughened walls with full-length as well as half-length ribs. Nusselt numbers, friction factors and thermal performances of all geometries are compared. The most important conclusion of this study is that the roughening of the partition walls enhances the heat transfer coefficients on those walls but, more importantly, enhances heat transfer coefficients on the primary walls considerably.
Rib Heat Transfer Coefficient Measurements in a Rib-Roughened Square Passage
Authors: Korotky G. J. , Taslim M. E.
Published: February 2015

Three staggered 90° rib geometries corresponding to blockage ratios of 0.133, 0.167 and 0.25 were tested for pitch-to-height ratios of 5, 8.5 and 10, and for two distinct thermal boundary conditions of heated and unheated channel walls. Comparisons were made between the surface averaged heat transfer coefficients and friction factors for ribs with rounded corners and those with sharp comers, reported previously. Heat transfer coefficients of the furthest upstream rib and that of a typical rib located in the middle of the rib-roughened region of the passage wall were also compared. It was concluded that: a) For the geometries tested, the rib average heat transfer coefficient was much higher than that for the area between the ribs. For the sharp-corner ribs, the rib average heat transfer coefficient increased with blockage ratio. However, when the corners were rounded, the trend depended on the level of roundness. b) High blockage ratio (e/Dh=0.25) ribs were insensitive to the pitch-to-height ratio. For the other two blockage ratios, the pitch-to-height ratio of 5 produced the lowest heat transfer coefficient. Results of the other two pitch-to-height ratios were very close, with the results of S/e = 10 slightly higher than those of S/e=8.5. c) Under otherwise identical conditions, ribs in the furthest upstream position produced lower heat transfer coefficients for all cases except that of the smallest blockage ratio with S/e of 5. In that position, for the rib geometries tested, while the sharp-comer rib average heat transfer coefficients increased with the blockage ratio, the trend of the round-corner ribs depended on the level of roundness, r/e. d) Thermal performance decreased with the blockage ratio. While the smallest rib geometry at a pitch-to-height ratio of 10 had the highest thermal performance, thermal performance of high blockage ribs at a pitch-to-height ratio of 5 was the lowest. e) The general effects of rounding were a decrease in heat transfer coefficient for the midstream ribs and an increase in heat transfer coefficient for ribs in the furthest upstream position.
Rotordynamic Forces due to Turbine Tip Leakage: Part I — Blade Scale Effects
Authors: Song Seung Jin , Martinez-Sanchez Manual
Published: February 2015

An experimental and theoretical investigation has been conducted on rotordynamic forces due to non-axisymmetric turbine tip leakage effects. This paper presents an actuator disc model which describes the flow response to a finite clearance at the rotor tip. The model simplifies the flow field by assuming that the radially uniform flow splits into two streams as it goes through the rotor. The stream associated with the tip clearance, or the underturned stream, induces radially uniform unloading of the rest of the flow, called the bladed stream. Thus, a shear layer forms between the two streams. The fraction of each stream and the strength of shear layer between the two are found as functions of the turbine loading and flow parameters without resorting to empirical correlations. The results show that this model’s efficiency predictions compare favorably with the experimental data and predictions from various correlations. A companion paper builds on this analysis to yield a model of the 3-D disturbances around an offset turbine and to predict the subsequent cross forces.
Application of a Multi-Block CFD Code to Investigate the Impact of Geometry Modeling on Centrifugal Compressor Flow Field Predictions
Authors: Hathaway Michael D. , Wood Jerry R.
Published: February 2015

CFD codes capable of utilizing multi-block grids provide capability to analyze the complete geometry of centrifugal compressors including, among others, multiple splitter rows, tip clearance, blunt trailing edges, fillets, and slots between moving and stationary surfaces. Attendant with this increased capability is potentially increased grid setup time and more computational overhead — CPU time and memory requirements — with the resultant increase in “wall clock” time to obtain a solution. If the increase in “difficulty” of obtaining a solution significantly improves the solution from that obtained by modeling the features of the tip clearance flow or the typical bluntness of a centrifugal compressor’s trailing edge, then the additional burden is worthwhile. However, if the additional information obtained is of marginal use then modeling of certain features of the geometry may provide reasonable solutions for designers to make comparative choices when pursuing a new design. In this spirit a sequence of grids were generated to study the relative importance of modeling versus detailed gridding of the tip gap and blunt trailing edge regions of the NASA large low speed centrifugal compressor for which there is considerable detailed internal laser anemometry data available for comparison.

The results indicate: 1) There is no significant difference in predicted tip clearance mass flow rate whether the tip gap is gridded or modeled. 2) Gridding rather than modeling the trailing edge results in better predictions of some flow details downstream of the impeller, but otherwise appears to offer no great benefits. 3) The pitchwise variation of absolute flow angle decreases rapidly up to 8% impeller radius ratio and much more slowly thereafter. Although some improvements in prediction of flow field details are realized as a result of analyzing the actual geometry there is no clear consensus that any of the grids investigated produced superior results in every case when compared to the measurements. However, if a multi-block code is available it should be used as it has the propensity for enabling better predictions than a single block code which requires modeling of certain geometry features. If a single block code must be used some guidance is offered for modeling those geometry features which can’t be directly gridded.
The Effect of Squeeze Film Damper Parameters on the Unbalance Response and Stability of a Flexible Rotor
Authors: Chu F. , Holmes R.
Published: February 2015

There has been much research work carried out on various aspects of individual squeeze-film dampers (SFDs) but very little on the interplay between a damper and the rotating assembly of which it forms a part. In this paper, a flexible rotor-bearing assembly in a configuration, typical of a small centrifugal pump and incorporating an SFD is investigated theoretically and experimentally from the points of view of forced vibration control and stability control. It is found that change in rotor unbalance, SFD static eccentricity ratio and SFD supply pressure can cause significant movement of system resonances and vibration resulting from excessive damping. The provision of an SFD also delays the onset of instability and because of its nonlinearity, the SFD contributes more damping than can a linear damper when the vibration amplitude becomes large as instability develops. It is shown that this instability is curbed at some limit cycle, whose frequency is a system natural frequency.
An Experimental Study of Turbine Vane Heat Transfer With Water-Air Cooling
Authors: Nirmalan Nirm V. , Weaver John A. , Hylton Larry D.
Published: February 2015

This paper presents data showing the improvement in cooling effectiveness of turbine vanes through the application of water-air cooling technology in an industrial/utility engine application. The technique utilizes a finely dispersed water-in-air mixture that impinges on the internal surfaces of turbine airfoils to produce very high cooling rates. An airfoil was designed to contain a standard impingement tube which distributes the water-air mixture over the inner surface of the airfoil. The water flash vaporizes off the airfoil inner wall. The resulting mixture of air-steam-water droplets is then routed through a pin fin array in the trailing edge region of the airfoil where additional water is vaporized. The mixture then exits the airfoil into the gas path through trailing edge slots.

Experimental measurements were made in a three-vane, linear, two-dimensional cascade. The principal independent parameters — Mach number, Reynolds number, wall-to-gas temperature ratio, and coolant-to-gas mass flow ratio — were maintained over ranges consistent with typical engine conditions. Five impingement tubes were utilized to study geometry scaling, impingement tube-to-airfoil wall gap spacing, impingement tube hole diameter, and impingement tube hole patterns. The test matrix was structured to provide an assessment of the independent influence of parameters of interest, namely, exit Mach number, exit Reynolds number, gas-to-coolant temperature ratio, water- and air-coolant-to-gas mass flow ratios, and impingement tube geometry.

Heat transfer effectiveness data obtained in this program demonstrated that overall cooling levels typical for air cooled vanes could be achieved with the water-air cooling technique with reductions of cooling air flow of significantly more than 50%.
Variable Cycle Powerplants for a Mach 2.7 Supersonic Civil Transport
Authors: Aleid Louay , Pilidis Pericles
Published: February 2015

The aim of the work outlined in this paper is to compare three different variable cycle jet engine concepts for future SSTs. These engines are: the Turbofan-Turbojet, the Mid-Tandem Fan engine and the Double Bypass Engine. The comparison is carried out on a basis of performance, handling and sizing issues.

This preliminary analysis compares S.F.C., size, variable geometry and cycle changes, and the effect of variable stator on the running lines of each compressor for each engine. The fuel bill, for two standard missions, is estimated as well.

These preliminary results indicate that the three engines are quite similar in terms of general suitability. The Mid Tandem Fan appears to be an attractive proposition from the point of view of sizing, however this comes with a small penalty in fuel consumption.
Periodic Aerodynamic Response of Axial Fan Rotor Blades to Nonuniform Inlet Flow Fields
Authors: Staiger M. , Stetter H.
Published: February 2015

An experimental investigation of the aerodynamic response of the rotor blading of a single stage low speed axial research compressor, which was exposed to wake type inlet flow disturbances was carried out at the Institute’s low speed compressor and fan research facility. The investigation comprised 5 hole pressure probe surveys of the nonuniform flow field at the rotor inlet and exit planes as well as direct recording of the unsteady surface pressure response by rotor blade mounted ‘fast response’ miniature pressure transducers. Forcing functions in terms of streamwise and transverse gust velocities were determined from the circumferential and radial distribution of the inlet flow properties. The blade surface pressure history of the unsteady aerodynamic response was recorded at several locations along span and along chord. The influence of steady stage loading on the forcing function as well as on the unsteady rotor blade response was investigated. At midspan the recorded local blade surface pressure histories were integrated to a spanwise unsteady blade force coefficient, which was correlated to a calculated force coefficient determined by a two-dimensional linearized unsteady aerodynamic analysis.
Characteristics of Wakes in Compressible Two-Dimensional Flows
Authors: Kurz Rainer
Published: February 2015

The goal of the paper is to describe wake parameters of wakes from turbine cascades in compressible flow especially in planes where the leading edge of the following blade row would be located.

The content of this paper is twofold: Data from experiments described in this paper and published data by different authors is used. Based on this data a theoretical approach is derived which describes the wake growth and the recovery of the velocity deficit. The theory is based on similarity assumptions. The derived equations depend on simple and readily available parameters such as overall losses, exit angle and Mach number. The paper follows the assumption that wakes can be described by similarity solutions. Conservation laws in an integral formulation are used to derive equations that describe the wake behavior downstream of the trailing edge of turbomachinery blades in compressible flows. The behavior of wakes will be described in terms of boundary layer dimensions (displacement and momentum thickness). In compressible turbine flows, the influence of the inviscid flow field is of great importance. In this paper an approach to take this influence into account when determining the behavior of the wake is presented.
Fuel-Specification Considerations for Biomass Pyrolysis Liquids to be Used in Stationary Gas Turbines
Authors: Moses Clifford A. , Bernstein Henry L.
Published: February 2015

A review of the physical and chemical properties of various biomass pyrolysis liquids suggests that they will require special consideration for use in current gas turbines for power generation. A new balance between fuel quality and engine design characteristics will have to found for the effective use of these liquids. Unfortunately, the values of many critical properties are beyond the range of experience with any distillate fuel, residual fuel, or alternate fuel such as coal liquids or shale oil. Furthermore, there appear to be some characteristics which are new and may require additional considerations in the fuel specification. Some system testing with biomass fuels covering the range of properties will be necessary to develop relevant relationships before design modifications can be made to accommodate biomass fuels and for fuel specifications to be established.
A High-Frequency-Response Pressure Probe for the Measurement of Unsteady Flow Between Two Rotors in a Hydrodynamic Turbomachine
Authors: Achtelik C. , Eikelmann J.
Published: February 2015

A new, specially-developed high-frequency-response pressure probe was used to measure the unsteady flow in the interaction region between the pump and the turbine in a hydrodynamic torque converter. In order to reduce the probe diameter, a single-hole, single-sensor cylindrical probe (⌀=1.33mm) was developed, to replace the standard multi-hole probe. The smaller the probe the higher the accuracy in unsteady flow. Therefore this is an improvement over three-hole probe. Three-hole probe measurements were simulated by recording data in three different angular positions. The time variable velocity vectors were determined using the probe’s calibration coefficients and the knowledge of the rotor positions (measured by angle-encoders) for every measurement value. During the data processing, a double ensemble averaging was carried out, taking into account the positions of the pump and the turbine.
Loss Production in the Wake of a Simulated Subsonic Turbine Blade
Authors: Roberts Quentin D. , Denton John D.
Published: February 2015

The time-averaged flow in the wake of a model of a turbine blade was surveyed using a three-hole pressure probe; boundary layer traverses were also carried out using a flattened pilot probe. Loss coefficients were derived from the mass-weighted deficit in stagnation pressure. Results showing the progression of loss with streamwise distance along the surface and the wake of the model are presented. It was found that the loss generated in the wake comprised one-third of the profile loss when a well-developed vortex street was present in the wake. This proportion was reduced by increasing the thickness of the suction surface boundary layer, and by simulating the deviation that occurs in a real turbine blade. In both cases the strength of the vortex street was also shown to have been reduced.
Development and Shop Test Results of a New 25–35MW Class Gas Turbine MF-221
Authors: Takeishi K. , Mori H. , Tsukagoshi K. , Takahama M.
Published: February 2015

Mitsubishi Heavy industries Ltd. developed a new high efficiency medium-size (25–35MW) gas turbine MF-221 to be used in a cogeneration plant. This gas turbine is an upscaled design of the MF-111 model, which has accumulated an operation experience of more than 1,020,000hrs. The improvement of performance and reliability was made possible by technology transfer from the latest 501F/701F gas turbine with respect to compressor and turbine aerodynamics, materials, coating and turbine cooling technology.

The MF-221 has a base load rating of 30MW at 1250°C turbine inlet temperature. Its thermal efficiency is 32% and 45% for simple and combined cycle application, respectively. It consists of a single shaft, 17-stage axial compressor, 10 can-type combustors and a 3-stage axial turbine. The prototype engine has been tested in a full-load test facility at Takasago Machinery Works to confirm the efficiency and the reliability of all parts exposed to high temperatures.
High Strength Diffusion Braze Repair for Gas Turbine Components
Authors: Wustman Roger D. , Hampson Leonard M. , Smith Jeffrey S. , Suneson Marc E.
Published: February 2015

The goal of all repair processes is to return the hardware to a serviceable condition. Diffusion braze repairs utilize metallurgical processes to achieve economical repairs of expensive gas turbine components, especially in the turbine section. Component repairs often require dimensional restoration and crack repair on the same part. To achieve this goal, a new diffusion braze repair alloy was developed that combines high strength crack repair and dimensional build up into one material. This new material has mechanical property strength approaching that of the base metal. The improved mechanical properties result from a homogenous gamma prime strengthened diffusion braze zone.

As part of an FAA approved test plan, the Howmet ESR (Effective Structural Repair) diffusion braze material was evaluated by tensile and stress rupture testing at elevated temperature. The test results showed high tensile strengths and long stress rupture life. In addition, the effect of the diffusion braze thermal cycle was evaluated on the base metal. A comparison was made between the gamma prime size and shape of engine run JT8D LPT vane clusters before and after the thermal cycle. The thermal cycle was shown to have a beneficial effect on the gamma prime size and shape relative to overaged engine run nozzles. The low cycle fatigue (LCF) life of MarM247 was also shown to improve with the ESR thermal cycle relative to a typical LPT nozzle heat treatment.
A Comparison of Full Surface Local Heat Transfer Coefficient and Flow Field Studies Beneath Sharp-Edged and Radiused Entry Impinging Jets
Authors: Gillespie D. R. H. , Guo S. M. , Wang Z. , Ireland P. T. , Kohler S. T.
Published: February 2015

Full heat transfer coefficient and static pressure distributions have been measured on the target surface under impinging jets formed by sharp-edged and large entry radius holes. These geometries are representative of impingement holes in a gas turbine blade manufactured by laser cutting and by casting, respectively. Target surface heat transfer has been measured in a large scale perspex rig using both the transient liquid crystal technique and hot thin film gauges. A range of jet Reynolds numbers, representative of engine conditions, has been investigated. The velocity variation has been calculated from static pressure measurements on the impingement target surface. The heat transfer to the target surface is discussed in terms of the interpreted flow field.
Advances in Gas Turbine Technology and the Digital Computer
Authors: Platt Melvin
Published: February 2015

Recent advances in gas turbine technology from computational fluid dynamics (CFD) to concurrent engineering are identified and discussed. These advances are placed in a historical context. Parallels are drawn between advances in gas turbine technology and digital computers. The advent of high-speed digital computers in the late 50s, followed by interactive operation and display graphics in the 70s. and orders-of-magnitude increases in affordable processing speed more recently, have each enabled key technologies for the gas turbine. Examples of such key technologies are given and their evolution is considered. Further, the impact of that technology on gas turbine development is discussed. Those perspectives provide a more coherent image of technology advancement, and thus a greater ability to identify new and future advances that will effect the evolution of gas turbines. The paper concludes with a look into the near future of gas turbine technology.
Development and Fabrication of Ceramic Gas Turbine Components
Authors: Tanaka Koichi , Tsuruzono Sazo , Kubo Toshifumi , Yoshida Makoto
Published: February 2015

Kyocera has been developing various ceramic components for gas turbines under the Ceramic Gas Turbine (CGT) Project funded by the Japanese Government. This project has set a turbine inlet temperature (TIT) of 1350°C as a final target.

For 1350°C TIT, we have developed a new silicon nitride material SN281, which has high stress rupture strength at elevated temperatures up to 1500°C. This material has excellent oxidation resistance as well.

We have also developed improved sintering and inspection technologies for the use of SN281 as engine components. We are able to fabricate rotors and nozzles of the gas generator turbine (GGT) in good agreement with design geometry requirements, by optimizing sintering conditions. Small defects were also successfully detected by microfocus X-ray radiography. The SN281 rotors have attained 120% of design rotating speed at room temperature.
Flow Interactions in the Combustor-Diffuser System of Industrial Gas Turbines
Authors: Agrawal Ajay K. , Kapat Jayanta S. , Yang Tah-teh
Published: February 2015

This paper presents an experimental/computational study of cold flow in the combustor-diffuser system of industrial gas turbines to address issues relating to flow interactions and pressure losses in the pre- and dump diffuses. The present configuration with can annular combustors differs substantially from the aircraft engines which typically use a 360 degree annular combustor. Experiments were conducted in a one-third scale, annular 360-degree model using several can combustors equispaced around the turbine axis. A 3-D computational fluid dynamics analysis employing the multidomain procedure was performed to supplement the flow measurements. The measured data correlated well with the computations. The airflow in the dump diffuser adversely affected the prediffuser flow by causing it to accelerate in the outer region at the prediffuser exit. This phenomenon referred to as the sink-effect also caused a large fraction of the flow to bypass much of the dump diffuser and go directly from the prediffuser exit to the bypass air holes on the combustor casing, thereby, rendering the dump diffuser ineffective in diffusing the flow. The dump diffuser was occupied by a large recirculation region which dissipated the flow kinetic energy. Approximately 1.2 dynamic head at the prediffuser inlet was lost in the combustor-diffuser system; much of it in the dump diffuser where the fluid passed through the narrow gaps and pathways. Strong flow interactions in the combustor-diffuser system indicate the need for design modifications which could not be addressed by empirical correlations based on simple flow configurations.
The Design, Manufacture and Successful Operation of a Very Small Turbojet Engine
Authors: van den Hout Franklin , Koullen Jo
Published: February 2015

This paper documents the design, manufacture and successful operation of a very small turbojet engine for particular use in radio controlled model jet aircraft and other small and unmanned drones.

This work commenced 6 years ago and basically this engine evolved around one off-the-shelf item: a radial low pressure compressor-turbine rotor from a modern automobile turbocharger system. All other major components such as the single stage compressor diffuser, reverse flow combustor, turbine first stage nozzles and inlet and exhaust ducts are newly manufactured items.

With an overall length of 310 mm, a diameter of 110 mm and a weight of 2.2 kg, this engine formed a great challenge upon both authors with respect to the development of each component. It was both a mixture of art and science. The three challenges were:

a. The reverse flow combustor with a length of 110 mm.

b. The rotor bearing module and vibration damping (balancing).

c. The single stage compressor diffuser.

The design point performance data at ISO conditions is:

Gross Thrust: 40 Newtons

Specific Fuel Consumption: 0.225 kg/N.h

Compressor Air Flow: 0.150 kg/s

Compressor Pressure Ratio: 1.90

Turbine Inlet Temperature: 680 °C

Rotational Speed: 100000 rpm

Turbine Fuel: JP3/JP4 kerosene+gas fuel

Maximum Sound Pressure Level: 90 dBA at 1 mtr

This paper will discuss the manufacturing and design techniques used and the performance and handling characteristics of the engine.
The Development of the Junkers Jumo 004B: The World’s First Production Turbojet
Authors: Meher-Homji Cyrus B.
Published: February 2015

This paper describes the pioneering work of Anslem Franz who, while working for the Junkers Engine company in Germany designed and made operational the world’s first production jet engine the Junkers Jumo 004 which was the powerplant for the formidable Messerschmitt ME 262 fighter. The paper covers the historical background of jet engine development in Germany during the Second World War and discusses design details of this remarkable axial flow, 1980 Lbs (900 Kg) thrust engine. The development represented a historic achievement for Anslem Franz and his design team at Junkers. Approximately 6,000 engines were built at the end of the second world war in the face of acute shortages and damage to German industry. The Jumo was brought from conceptual design to production in a span of four years.

Franz joined Avco Lycoming in 1952 and worked for 16 years. He retired as Vice President in 1968 after making prolific contributions to the development of several Avco engines including the T53. the T55 and the AGT-1500. Anslem Franz passed away at the age of 94 in Stratford, Connecticut. This paper is a modest tribute to a jet engine pioneer who, in spite of his extensive contributions to gas turbine technology, will always be remembered as the man who designed the world’s first production turbojet.
Evaluation of Commercial Coatings on MarM-002, IN-939 and CM-247 Substrates
Authors: Goedjen J. G. , Wagner G. P.
Published: February 2015

As part of the U.S. Department of Energy Advanced Turbine Systems Program, the performance of Chromalloy RT122, RT122 over RT69 and the Howmet 150L bond coats were evaluated for use in the next generation of Westinghouse combustion turbines. Air plasma sprayed and electron beam physical vapor deposition 8% yttria stabilized zirconia thermal barrier coatings were applied to the bond coats. The coating systems were evaluated in air at 2102°F (1150°C), cooling to room temperature once per day. The life-limiting failure mode in both air plasma sprayed (APS) and electron beam - physical vapor deposition (EB-PVD) coating systems is the oxidation of the bond coat. The coating life is related to the growth rate and morphology of the thermally grown oxide. The superior performance of RT122 on MarM-002, the duplex bond coat system of RT122 over RT69 on MarM-002 and Howmet 150L on MarM-002 can be related to the development of a uniform, slow growing oxide scale. The development of a non-uniform oxidation front contributes to the reduced life of RT122 on IN-939 and CM-247.
Development of Ceramic Stator Vane for 1500°C Class Gas Turbine
Authors: Machida Takashi , Nakayama Masato , Wada Katsuo , Hisamatsu Tooru , Yuri Isao , Watanabe Kazunori
Published: February 2015

Employing ceramic materials for the critical components of industrial gas turbines is anticipated to improve the thermal efficiency of power plants. We have developed a first stage ceramic stator vane for a 1500°, 20MW class industrial gas turbine by improving our original one for a 1300°C class gas turbine. Our stator vane has a hybrid ceramic/metal structure composed of a ceramic shell, a metal core and a heat insulating layer. This composition increases the strength of the brittle ceramic parts and reduces the amount of cooling air. To improve the durability and reliability of the stator vane in 1500°C combustion gas, the ceramic shell uses silicon carbide instead of silicon nitride, and its configuration is improved. Furthermore, we use an internal cooling system to control the temperature of the metal core. Thermal loading cascade tests are conducted to prove the reliability and cooling performance of the stator vane.
An Investigation of Heat Transfer by Leading Edge Film Cooling Applying the Naphthalene Sublimation Technique
Authors: Richter J. , Jung K. , Hennecke D. K.
Published: February 2015

The dependence of heat transfer on film cooling near the leading edge of a blade was investigated using the naphthalene sublimation technique and applying the analogy between heat and mass transfer. Therefore, the local sublimation rate with and without film cooling was measured. The symmetric leading edge was cooled by an air mass flow out of two staggered rows of holes. The measurements were carried out with a constant Reynolds number Re = 80000, different incidence angles φ = 0° to 10° and a blowing rate varying from M = 0.3 to 2.5.

The flow without film cooling was visualized around the leading edge with smoke to indicate the existence of separation bubbles. To determine the dependence of incidence angle and blowing rate on jet trajectories, smoke was mixed to the cooling air.

The mass transfer coefficient was determined with the naphthalene sublimation technique. Due to the high resolution of the sublimation technique the local mass transfer distribution around the cooling holes could also be measured. Furthermore, the location of stagnation points and separation bubbles were investigated.

The results of the tests without film cooling were also compared with those obtained by observing stagnation point mass transfer on a cylinder and with those by laminar flow across a flat plate. The mass transfer coefficient of film cooling experiments was related to the mass transfer coefficient without film cooling to describe the local dependence of heat transfer coefficient on film cooling. An increase on relativ heat transfer near the film cooling holes is obtained by increasing the blowing rate. No further influence on heat transfer along the pressure side is detected for an incidence angle larger than 10° as the cooling films were shifted around the leading edge from the pressure to the suction side.
Engine Testing of a Natural Gas-Fired, Low-NOx, Variable Geometry Gas Turbine Combustor for a Small Gas Turbine
Authors: Hayashi Shigeru , Yamada Hideshi , Shimodaira Kazuo
Published: February 2015

The development of a variable geometry lean-premixed combustor is in progress at NAL. Engine testing has been cooducted by using a natural gas-fueled 210-kW gas turbine to demonstrate the capability of ultra-low NOx emissions over a wide range of eogine operation. This paper describes the effort of engine testing of the combustor to achieve NOx emissions of the 10-ppm level. Fuel was staged to the non-premixed pilot and premixed main burners. A butterfly valve air splitting system was employed to maintain both low NOx emissions and high efficieocy over a wide operating range of the engine. The engioe was operated in the lean-premixed, low NOx emissions mode from idle to full power. Over the whole operating conditions from idle to full power, NOx emissions were reduced to levels less than 25 ppm (15% O2 dry). The NOx emissions level for a nearly constant combustion efficiency decreased with increasing power or turbine inlet temperature. At operating conditions of 90% to full power, NOx emissions levels of 12 to 8 ppm (15% O2 dry) were measured with combustion efficiencies of 99.7 to 99.1%.
High Speed Rotor Losses in a Radial 8-Pole Magnetic Bearing: Part 1 — Experimental Measurement
Authors: Kasarda M. E. F. , Allaire P. E. , Maslen E. H. , Brown G. R. , Gillies G. T.
Published: February 2015

The continual increase in the use of magnetic bearings in various capacities, including high speed aerospace applications such as jet engine prototypes, dictates the need to quantify power losses in this type of bearing. The goal of this study is to present experimentally measured power losses during the high speed nperatinn nf a pair of magnetic bearings. A large scale test rotor has been designed and built to obtain unambiguous power loss measurements while varying a variety of test parameters. The test apparatus consists of a shaft supported in two radial magnetic bearings and driven by two electric motors also mounted nn the shaft. The power losses of the spinning rotor are determined from the time rate of change of the kinetic energy of the rotor as its angular speed decays during free rotatinn. Measured results for the first set of magnetic bearings, a pair of 8-pole planar radial bearings, are presented here. Data from three different parameter studies including the effect of the hias flux density, the effect of the bearing pole configuration, and the effect of the motor stator on the power loss are presented. Rundown pints of the test with the bearings in the paired pole (NNSS) versus the alternating (NSNS) pole configuration shnw only small differences, with losses only slightly higher when the poles are in the alternating pole (NSNS) configuration. Loss data was also taken with the motor statnrs axially removed from the mntnr rotors for comparison with the case where the mntor stators are kept in place. No measurable difference was observed between the two cases, indicating negligible windage and residual magnetic effects. Throughout mnst of the speed range the dominant loss mechanism appears to be eddy currents.
An Approach for the Development of an Aerodynamic-Structural Interaction Numerical Simulation for Aeropropulsion Systems
Authors: Naziar Javaid , Couch Rich , Davis Milt
Published: February 2015

Traditionally, aeropropulsion structural performance and aerodynamic performance have been designed separately and later mated together via flight testing. In today’s atmosphere of declining resources, it is imperative that more productive ways of designing and verifying aeropropulsion performance and structural interaction be made available to the aerospace industry. One method of obtaining a more productive design and evaluation capability is through the use of numerical simulations. Currently, Lawrence Livermore National Laboratory has developed a generalized fluid/structural interaction code known as ALE3D. This code is capable of characterizing fluid and structural interaction for components such as the combustor, fan/stators, inlet and/or nozzles. This code solves the 3D Euler equations and has been applied to several aeropropulsion applications such as a supersonic inlet and a combustor rupture simulation. To characterize aerodynamic-structural interaction for rotating components such as the compressor, appropriate turbomachinery simulations would need to be implemented within the ALE3D structure. The Arnold Engineering Development Center is currently developing a three-dimensional compression system code known as TEACC (Turbine Engine Analysis Compressor Code). TEACC also solves the 3D Euler equations and is intended to simulate dynamic behavior such as inlet distortion, surge or rotating stall. The technology being developed within the TEACC effort provides the necessary turbomachinery simulation for implementation into ALE3D. This paper describes a methodology to combine three-dimensional aerodynamic turbomachinery technology into the existing aerodynamic-structural interaction simulation, ALE3D to obtain the desired aerodynamic and structural integrated simulation for an aeropropulsion system.
Simulation of Trailing Edge Vortex Shedding in a Transonic Turbine Cascade
Authors: Currie Tom C. , Carscallen William E.
Published: February 2015

Mid-span losses in the NRC transonic turbine cascade peak at an exit Mach number (M2) of ∼1.0 and then decrease by ∼40% as M2 is increased to the design value of 1.16. Since recent experimental results suggest that the decrease may be related to a reduction in the intensity of trailing edge vortex shedding, both steady and unsteady quasi-3D Navier-Stokes simulations have been performed with a highly refined (unstructured) grid to determine the role of shedding. Predicted shedding frequencies are in good agreement with experiment, indicating the blade boundary layers and trailing edge separated free shear layers have been modelled satisfactorily, but the agreement for base pressures is relatively poor, probably due largely to false entropy created downstream of the trailing edge by numerical dissipation. The results emphasize the importance of accounting for the effect of vortex shedding on base pressure and loss.