bluuebunny/crossref_metadata_2025_split huggingface dataset:
Advanced Jet Fuels — JP-4 Through JP-8 and Beyond
Authors: Harrison W. E. , Mongia H. C. , Heneghan S. P. , Ballal D. R. 
Published: February 2015

Jet fuel requirements have evolved over the years as a balance of the demands placed by advanced aircraft performance (technological need), fuel cost (economic factors), and fuel availability (strategic factors). In a modern aircraft, the jet fuel is the primary coolant for aircraft and engine subsystems and provides the propulsive energy for flight. To meet the evolving challenges, the U.S. Air Force, industry and academia have teamed to develop new and improved fuels that offer increased heat sink and thermal stability, properties that will enable improved aircraft design and decrease fuel system maintenance due to fuel fouling/coking. This paper describes the team effort to develop improved JP-8, named “JP-8+100”, that offers a 55C (100F) improvement in thermal stability and a 50% increase in heat sink.
The government, industry, and academia team has made numerous advances in the development of JP-8+100 with a more complete understanding of the fundamental processes of deposition, new approaches to reducing fouling/coking, and new tests and models to assist the designers of aircraft and engine fuel systems. Some of the principal advances are: new quantitative research devices and fuel system simulators that provide thermal stability information that cannot be obtained using the standard JFTOT test; new techniques to measure oxygen consumption and fuel degradation pathways; a free radical theory to explain behaviors such as the inverse relationship between thermal and oxidative stability, advanced CFD models with coupled degradation chemistry, and a new thermal stability ranking scale for jet fuels. The insight obtained has been applied to the development of an additive package for JP-8 that shows thermal stability improvements equal to or greater than the stated goal and enables the development of even higher thermal stability fuels such as JP-900.
Fracture Toughness of Structural Ceramics Under Biaxial Stress State by Anticlastic Bending Test
Authors: Ono Takashi , Kaji Masaki 
Published: February 2015

Mixed-mode fracture of structural ceramics under biaxial stress state was investigated by an anticlastic bending test using the controlled surface flaw technique. The stress state of the anticlastic bending specimen is biaxial. This test enables the study of fractures under pure mode I, pure mode II, or any combination of mode I and mode II loading.
To discuss the experimental results, a parameter ‘T’ was introduced to the modified maximum hoop stress criterion. This parameter represents frictional effects of crack interfaces on the mixed-mode fracture and can be obtained experimentally. Relative magnitudes of mode I and mode II stress intensity factors and the directions of non-coplanar crack extension angles were predicted using the parameter ‘T’. Reasonable agreement with the experimental results was obtained.
Wave Cycle Design for Wave Rotor Gas Turbine Engines With Low NOx Emissions
Authors: Nalim M. Razi , Resler Edwin L. 
Published: February 2015

The wave rotor is a promising means of pressure-gain for gas turbine engines. This paper examines novel wave rotor topping cycles which incorporate low-NOx combustion strategies. This approach combines two-stage ‘rich-quench-lean’ (RQL) combustion with intermediate expansion in the wave rotor to extract energy and reduce the peak stoichiometric temperature substantially. The thermodynamic cycle is a type of reheat cycle, with the rich-zone air undergoing a high pressure stage. Rich-stage combustion could occur external to or within the wave rotor.
An approximate analytical design method and CFD/combustion codes are used to develop and simulate wave rotor flow cycles. Engine cycles designed with a bypass turbine and external combustion demonstrate a performance enhancement equivalent to a 200–400°R (110–220°K) increase in turbine inlet temperature. The stoichiometric combustion temperature is reduced by 300–450°R (170–250°K) relative to an equivalent simple cycle, implying substantially reduced NOx formation.
The Nuclear Gas Turbine: Towards Realization After Half a Century of Evolution
Authors: McDonald Colin F. 
Published: February 2015

This paper has been written exactly 50 years after the first disclosure of a closed-cycle gas turbine concept with a simplistic uranium heater. Clearly, this plant was ahead of its time in terms of technology readiness, and the closed-cycle gas turbine was initially deployed in a cogeneration mode burning dirty fuels (e.g., coal, furnace gases). In the 1950s through the mid 1980s about 20 of these plants operated providing electrical power and district heating for European cities. The basic concept of a nuclear gas turbine plant was demonstrated in the USA on a small scale in 1961 with a mobile closed-cycle nitrogen gas turbine [330 KW(e)] coupled with a nuclear reactor. In the last three decades, closed-cycle gas turbine research and development, particularly in the U.S. has focused on space power systems, but today the utility size gas turbine-modular helium reactor (GT-MHR) is on the verge of being realized. The theme of this paper traces the half century of closed-cycle gas turbine evolution, and discusses the recent enabling technologies (e.g., magnetic bearings, compact recuperator) that now make the GT-MHR close to realization.
The author would like to dedicate this paper to the late Professor Curt Keller who in 1935 filed the first closed-cycle gas turbine patent in Switzerland, and who exactly 50 years ago, first described a power plant involving the coupling of a helium gas turbine with a uranium heater.
Transition Control and Performance of the Selective Bleed Variable Cycle Turbofan
Authors: Ulizar Inaki , Pilidis Pericles 
Published: February 2015

The selective bleed turbofan is a two shaft, three compressor, variable cycle aircraft engine. At subsonic flight speeds it operates as a medium bypass turbofan. It becomes a low bypass turbofan when flying faster and is capable of supersonic cruise in the dry mode.
The aim of this paper is to outline the requirements and response of the engine during the transition phase from one mode of operation to the other. Thus it is follow-on work of Ref. 7. To achieve this several control devices can be employed. These are the fuel flow, the variable compressor stators, the nozzle areas and the valve areas of the bypass ducts.
The preliminary analysis described in this paper indicates that all the criteria of performance are satisfied and that the transition can be carried out successfully provided the control variables are co-ordinated properly.
Unsteady Flow Field due to Nozzle Wake Interaction With the Rotor in an Axial Flow Turbine: Part II — Rotor Exit Flow Field
Authors: Zaccaria Michael A. , Lakshminarayana Budugur 
Published: February 2015

The two-dimensional steady and unsteady flow field at midspan in a turbine rotor has been investigated experimentally using an LDV with an emphasis on the interaction of the nozzle wake with the rotor flow field. The velocity measurements are decomposed into a time-averaged velocity, a periodic velocity component and an unresolved velocity component. The results in the rotor passage were presented in Part I. The flow field downstream of the rotor is presented in this paper.
The rotor wake profiles and their decay characteristics were analyzed. Correlations are presented which match the decay of the various wake properties. The rotor wake velocity defect decays rapidly in the trailing edge region, becoming less rapid in the near and far wake regions. The rotor wake semi-wake width increases rapidly in the trailing edge region and then grows more gradually in the near and far wake regions. The decay of the maximum unresolved unsteadiness and maximum unresolved velocity cross correlations are very rapid in the trailing edge region and this trend slows in the far wake region. In the trailing edge region, the maximum periodic velocity correlations are much larger than the maximum unresolved velocity correlations. But the periodic velocity correlations decay much faster than the unresolved velocity correlations. The interaction of the nozzle and rotor wakes are also studied. While the interaction of the nozzle wake with the rotor wake does not influence the decay rate of the various wake properties, it does change the magnitude of the properties. These and other results will be presented in this paper.
Assessment of Two- and Three-Scale k-ε Models for Rotating Cavity Flows
Authors: Guo Zhou , Rhode David L. 
Published: February 2015

A three-scale k-ε turbulence model was recently developed for complex flows such as the rotor-rotor and rotor-stator cavities found in gas turbine engines. The three-scale model is a logical extension of the previous two-scale k-ε model of Ko and Rhode (1990). Both multi-scale turbulence models are presented and assessed via comparison with measurements for possible adoption in future cavity computations. A single computer code solving the 2-D axisymmetric Navier-Stokes equations with a “switch” for selecting among the various turbulence models being compared was used. It was found for both cavity cases that the three-scale model gives a marginal improvement over the two-scale model. Further, both multi-scale models give a substantial improvement over the standard k-ε model for the rotor-stator case, especially in the near-wall region where different eddy sizes are found. However, the feasibility of using a multi-scale model for the rotor-rotor case is unclear since it gives improved values over the standard high-Re model in some regions but worse values in other regions.
In addition, the solutions provide enhanced insight concerning the large changes in flow pattern previously photographed in the rotor-rotor case as rotation increases. In particular, it is shown how: (a) the number of recirculation zones increase with increasing rotation rate and (b) the recirculation zones decrease in size with a decreasing G ratio.
Combustor Flame Sensor With High Temperature Electronics
Authors: Glasheen Wm. Michael , Cusack Deidre E. , Steglich Helmar R. 
Published: February 2015

A high temperature solid state turbine flame sensor has been developed and is being tested for eventual use as a combustor performance sensor. It directly senses only the flame deep ultraviolet without any response to hot component infrared energy (> 700 nanometers); the dynamic range is large; and the response time is fast enough for combustor control, i.e., less than 200 milliseconds.
The sensor electronics operate up to 250°C and some detector performance data has been taken as high as 540°C as described by Cusack et al (1994). The design uses recently available SiC electronic components, other components specially tested for the application, and proprietary techniques of electronic component packaging. Specific experience in packaging turbine engine optical and temperature sensors is necessary for this unique high temperature electronic technology.
A test program for discrete components indicates what elements are available for this temperature range and prototype sensor data from both laboratory qualification tests and engine performance tests verify the design.
Enhanced Mixing of 2D Lobed Nozzles
Authors: Liu Huo-Xing , Wu Shou-Sheng 
Published: February 2015

The jet axial velocity decay and velocity distributions of two 2D Lobed Nozzles (2DLN), and three baseline nozzles, one circular and two rectangular with different aspect ratios (AR), were measured and compared at low velocity (M0 <0.35) and ambient temperature conditions. The five nozzles have the same exit area. Test results show:
1) The jet axial velocity decay of the 2DLN may be characterized by three distinct regions; i.e., “potential core region”, where the jet axial velocity almost remains constant; “rapid decay region”, where streamwise and normal vortices play major roles for enhanced mixing; and, “smooth-down decay region”, where the mixing process is dominated by viscous shear layer spreading and small-scale turbulence.
2) The jet potential core length of the two 2DLN tested is only half to one-third that of the baseline rectangular nozzle (AR=4.37), and about one-fourth to one-sixth compared with the baseline circular nozzle. The length, in which the jet mixed with surrounding air is nearly uniform, is one to two times that of the 2DLN equivalent exit diameter, and depends on lobe design.
An Advanced Control System for Turbofan Engine: Multivariable Control and Fuzzy Logic (Application to the M88-2 Engine)
Authors: Garassino Alain 
Published: February 2015

The search for better performance of present and future turbofan engine involves an increase on the number of variable geometries and thus of control loops.
As we can not or do not want to disregard the interaction between loops any more, the future control systems will therefore be multivariable. The aim of the architecture of multivariable control presented here is to optimize a performance index during transients.
This architecture consists of an inner loop which optimizes the performance index taking in account the limitations, an outer loop which brings the nominal steady-state offsets to zero and a trajectory which allows to take into account the topping schedule limitation.
This basic architecture can be improved by fuzzy supervisor.
Indeed, two control outputs are generated according to the description above:
- the first one optimizes the thrust and does not care very much about LP stall margin limitation,
- the second one optimizes again the thrust and strongly takes low pressure stall margin limitation into account.
The fuzzy logic then allows to do a compromise between these two control outputs according to the engine state.
Simulation results showing the efficiency of the method are given.
Integrated Turbine-Compressor Controls Retrofit for an Olefins Unit
Authors: Gaston John R. , Piercy W. Brian , Harclerode C. Scott 
Published: February 2015

The Olefins Unit that is the subject of this case study has been operating for 25 years. Recently, the unit initiated a control system retrofit program to increase availability, save energy, and improve access to operating information. New control systems were installed on the ethylene, propylene and furnace gas compressor trains. The gas compression equipment consists of single and multi-case compressor trains driven by steam and gas turbines and electric motors.
Significant control system improvements were made to the turbine/compressor speed/load regulation and temperature limiting. The systems also execute “safety system” logic for process and machinery protection. In addition to integrated turbine compressor control, the strategy that incorporates all control functions for the entire compresor train, a new anti-surge algorithm is included. To meet more stringent availability requirements imposed by integration, a triple modular redundant (TMR) system structure is employed. The surge algorithm described in this paper accurately predicts where surge occurs, regardless of changes in gas composition and conditions (e.g., molecular weight, temperature, etc.), and allows the integrated controls to compensate accordingly. A PC workstation-based operator display is provided for enhanced operator awareness of machinery conditions. This paper describes the requirements and implementation of this new approach to control.
Endwall Heat Transfer and Aerodynamic Measurements in an Annular Cascade of Nozzle Guide Vanes
Authors: Spencer M. C. , Lock G. D. , Jones T. V. , Harvey N. W. 
Published: February 2015

Aerodynamic and heat transfer measurements have been made on the hub and casing endwalls of an annular cascade of high pressure nozzle guide vanes. The measurements have been made over a range of engine representative Mach and Reynolds numbers and with large levels of freestream turbulence intensity.
The transient liquid crystal technique has been employed, which has the advantage of yielding full surface maps of heat transfer coefficient. Computational predictions and aerodynamic measurements of Mach number distributions on the endwall surfaces are also presented, along with surface-shear flow visualisation using oil and dye techniques. The heat transfer results are discussed and interpreted in terms of the secondary flow and Mach number patterns.
Enhancing Performance of Silicon-Modified Slurry Aluminides on Turbine Components Operating in Marine Environments
Authors: Berry David , Meelu Mehar Chand , McMordie Bruce G. , Kircher Thomas A. 
Published: February 2015

A variety of coatings have been designed to protect turbine components from corrosion due to the combined effects of environmental contaminants, fuel impurities and elevated temperatures. The most effective of these systems rely upon formation of a protective alumina scale to act as a barrier between the gas path environment and the component.
Protection offered by these alumina-forming high temperature coatings is increased by a number of additive elements, including platinum and chromium, but silicon (Si) is found to be especially beneficial in coatings exposed to high concentrations of sulfur in marine environments. Silicon-modified slurry aluminides are shown to resist to both high temperature and low temperature hot corrosion on both nickel and cobalt alloys in marine service.
Laboratory tests show this corrosion resistance can be further enhanced by redistributing critical elements (particularly silicon) within the microstructure of the silicon-modified aluminide. The benefits of these changes are demonstrated in field engine trials.
Advances in Laser Drilling of Turbine Engine Components
Authors: VanderWert Terry L. 
Published: February 2015

The application of laser systems for drilling turbine engine components has continued to grow. New designs for components are being made as understanding of the process has increased and as capability of laser systems has grown.
Advances in process control have led to higher throughput and quality in automatic production. Greater understanding of the laser drilling process has led to improved methods for controlling the spatter and remelt that are characteristic of laser processing. Availability of high speed. PC based controls has facilitated high speed sensing of the component location for precise and repeatable positioning of laser drilled features.
This paper describes recent advances in laser drilling turbine engine components. Current capabilities of laser drilling are summarized.
An On-Line System for Heterogeneous Distributed Computing and Advanced Visualization of Test Cell Data
Authors: Clark David A. 
Published: February 2015

In most turbine engine testing facilities, the tools and techniques of computational fluid dynamics (CFD) and advanced visualization have never been applied to facilitate (near) real-time analysis of the test hardware. New computer software technology has now been applied which allows server-to-client remote procedure calls (RPC), enabling supercomputers to be called from within the online test scanning program. Coupled with advanced visualization software and graphics workstations, it is possible to view the inside of a test while it is being conducted. Such capability can be as valuable to researchers in steering tests as X-rays are to doctors in diagnosing health.
This report presents results from a library of software for on-line visualization. Using this system, a full turbomachine (compressor) has been visually analyzed by interpolating pressure instrument rakes to give a full flow field view of the engine (compressor). All data values at each grid cross-section are non-dimensionalized and viewed at varying ranges of iso-distortion surfaces. Regions of low or high energy can be seen as they proceed through the compressor stages. A full range of capabilities are displayed for both pressure and temperature using computer animation techniques recorded to video. Such views are unique and may provide extra information to help understand flow phenomena such as inlet distortion and how it relates, for example, to stall margin.
CFD efforts are also described in conjunction with the use of RPC to supercomputers. A stream function meridional, 2D/quasi-3D solution to five blade rows is shown in context with rotating blade rows and shown on video. The value of the computer work is all generic and can be applied in almost any scientific area where on-line computer systems are used.
Specification, Development, and Testing of the FT8-2 Dry Low NOx Control System
Authors: Bell Russell C. , Prete Thomas W. , Stewart Jeffery T. 
Published: February 2015

This paper describes the specification, development and testing of the FT8-2 Dry Low NOx control system, and how the lean bum process requires an integration of the control system and combustion hardware. The FT8-2 digital fuel control system was developed to achieve the precise multi-zone fuel metering of both gas and liquid fuels, the calculation of combustor air flow necessary to achieve Dry Low NOx and the traditional governing/limiting control loops necessary for safe, stable engine operation.
The achievement of the system design goals was accomplished by the concurrent development of software Based fuel metering algorithms and fuel metering hardware. The fuel metering hardware utilizes an all electronic valve positioner, employing a combination of feedback and software to achieve closed loop control of actual fuel flow. Extensive testing under actual gas flow conditions and closed loop bench testing using a real time engine model and fuel system model was conducted to prove system operation and develop system transient response prior to Installation on the test engine. The setup and results of the flow testing and dosed loop testing are described.
The paper describes the control scheme used to apportion the gas fuel between combustion zones and how external conditions such as ambient temperature and fuel gas composition effect the apportionment.
The paper concludes with a description of the control system installation in the engine test cell and a review of engine test results.
Final Report of the Key Technology Development Program for a Next Generation High Temperature Gas Turbine
Authors: Sato M. , Kobayashi Y. , Matsuzaki H. , Aoki S. , Tsukuda Y. , Akita E. 
Published: February 2015

There is a strong demand for efficient and clean power generating systems to meet recent energy saving requirements and environmental regulations. A combined cycle power plant is one of the best solutions to the above.
Tohoku Electric Power Co., Inc. and Mitsubishi Heavy Industries, Ltd. have jointly developed three key technologies for a next generation 1,500°C class gas turbine. The three key technologies consist of (1) high temperature low NOx combustion system, (2) row I turbine vane and blade with advanced cooling schemes, and (3) advanced heat resistant materials, verified by HTDU (High Temperature Demonstration Unit).
This paper describes the results of the above mentioned 6 year joint development.
Development of the Taurus 70 Industrial Gas Turbine
Authors: Rocha George , Saadatmand Mohammad , Bolander Gary 
Published: February 2015

Solar Turbines Incorporated has developed the Taurus 70 gas turbine in response to growing market demands in the 7 MW size range. The simple cycle, two shaft engine is rated for 7.1 MW and 34% thermal efficiency at the ISO inlet condition. The product development strategy adopted for the Taurus 70 was to incorporate proven technology that has been demonstrated with the existing Taurus 60 and Mars engines. The final design configuration was influenced by the use of an uprated Taunts 60 compressor assembly to achieve thermodynamic cycle parameters similar to the Mars engines. The standard engine configuration also includes a dry, lean-premix, combustion system to provide a gas turbine with the lowest emission and highest simple cycle efficiency in its size class.
This paper describes the proven product technology, basic engine configuration and development test strategy involved in the development of the new Taurus 70 gas Turbine.