bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applications of Continuous Fiber Reinforced Ceramic Composites in Military Turbojet Engines
Authors: Spriet Patrick , Habarou Georges 
Published: February 2015

Over the last twenty years, significant performance improvements of turbojet engines have been achieved by optimizing engine thermodynamic cycle along with the introduction of new materials providing higher temperature capability and weight reduction.
Metal Matrix Composites (MMC) and Ceramic Matrix Composites (CMC) are candidate material systems to meet the required thrust-to-weight ratio of 15 or higher.
Continuous fiber reinforced ceramic composites, which have been developed by SEP for more than 15 years for thermostructural applications in oxidative environment, aim at increased operating temperature over superalloys and intermetallic alloys.
This paper is a review of the main CMC component demonstrations performed by SEP over the last 10 years for turbojet engines along with an analysis of consequences on materials development and design methodology.
The development status of a new thermostructural material specifically developed for turbojet environment with the prospect of higher design stress allowables and longer operating life at high temperature is presented.
Effects of Surface Roughness on Film Cooling
Authors: Schmidt Donald L. , Sen Basav , Bogard David G. 
Published: February 2015

A flat plate test section was used to study how surface roughness representative of an in-service turbine affects the film cooling adiabatic effectiveness and heat transfer coefficient for a round hole geometry. The injection was from a single row of round film cooling holes with injection angle of 30°. The density ratio of the injectant to the mainstream was 2.0 for the adiabatic effectiveness tests, and 1.0 for the heat transfer coefficient tests. A range of momentum flux ratios was examined to characterize the adiabatic effectiveness and heat transfer performance. Streamwise distributions of adiabatic effectiveness and heat transfer coefficients were obtained along the hole center line, and lateral distributions extending to halfway between hole centerlines were obtained at selected streamwise locations to 90 hole diameters downstream. Two rough surfaces with a factor of two difference in roughness levels were compared to an aerodynamically smooth surface.
Both rough surfaces degraded the film cooling effectiveness with increasing degradation farther downstream. Degradation of film cooling effectiveness was greater at low momentum flux ratios. At momentum flux ratios high enough so that the cooling jets completely detached from the surface, the rough surfaces slightly increased adiabatic effectiveness in some cases. There was little difference in the effectiveness results between the two rough surfaces. Film cooling injection had little effect on heat transfer rates for any of the surfaces.
A Novel Fluids Research Technique: Three-State Anemometry
Authors: Funes-Gallanzi M. 
Published: February 2015

A new flow measurement technique is described which allows for the non-intrusive simultaneous measurement of flow velocity, density, and viscosity. The viscosity information can be used to derive the flow field temperature. The combination of the three measured variables and the perfect-gas law then leads to an estimate of the flow field pressure. Thus, the instantaneous state of a flow field can be completely described.
Three-State anemometry (3SA), a derivative of PIV, which uses a combination of three monodisperse sizes of styrene seeding particles is proposed. A marker seeding is chosen to follow the flow as closely as possible, while intermediate and large seeding populations provide two supplementary velocity fields, which are also dependent on fluid density and viscosity. A simplified particle motion equation, for turbomachinery applications, is then solved over the whole field to provide both density and viscosity data. The three velocity fields can be separated in a number of ways. The simplest and that proposed in this paper is to dye the different populations and look through interferometric filters at the region of interest.
The two critical aspects needed to enable the implementation of such a technique are a suitable selection of the diameters of the particle populations, and the separation of the velocity fields. There has been extensive work on the seeding particle behaviour which allows an estimate of the suitable particle diameters to be made. A technique is described in this paper to allow the separation of μm range particle velocity fields through fluorescence (separation through intensity also being possible). Some preliminary results by computer simulations of a 3SA image are also presented. The particle sizes chosen were 1 μm and 5 μm tested on the near-wake flow past a cylinder to investigate viscosity only, assuming uniform flow density. The accuracy of the technique, derived from simulations of swirling flows, is estimated as 0.5% RMS for velocity, 2% RMS for the density and viscosity, and 4% RMS for the temperature estimate.
Development of the Next Generation 1500°C Class Advanced Gas Turbine for 50Hz Utilities
Authors: Aoki S. , Tsukuda Y. , Akita E. , Iwasaki Y. , Tomat R. , Rosso M. , Schips C. 
Published: February 2015

The 701G1 50Hz Combustion Turbine continues a long line of large heavy-duty single-shaft combustion turbines by combining the proven efficient and reliable concepts of the 501F and 701F. The output of the 701G1 is 255MW with combined cycle net efficiency of over 57%. A pan of component development was conducted under the joint development program with Tohoku Electric Power Co., Inc. and a part of the design work was carried out under the cooperation with Westinghouse Electric Corporation in the U.S.A. and Fiat Avio in Italy.
This gas turbine is going to be installed to “Higashi Niigata Power Plants NO.4” of Tohoku Electric Power Co., Inc. in Japan. This plant will begin commercial operation in 1999.
This paper describes some design results and new technologies in designing and developing this next generation 1500°C class advanced gas 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.
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.
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.
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.
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.
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.
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.
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.