bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel Technique for the Internal Blade Cooling
Authors: Glezer B. , Moon H. K. , O’Connell T. 
Published: February 2015

Development of an adequate air cooling system for the thermally highly loaded leading edge and tip of the blade, that is cost effective and also relatively insensitive to manufacturing tolerances and operating environment continues to be one of the major challenges in advanced gas turbine design. Extensive studies on the convective (including impingement) and film cooling techniques produced remarkable progress in achieving a high cooling effectiveness level for turbine airfoils. However, in the case of turbine blades, application of these techniques has severe limitations. Highly effective impingement cooling needs to be combined with film discharge of the spent air to avoid a negative impact of crossflow on internal heat transfer and also provide additional thermal protection of the surface downstream of the discharge holes. Noticeable aerodynamic penalties, stress concentration and significant increase in manufacturing cost limit application of blade film cooling, particularly for moderately high operating temperatures.
Search for a highly effective robust design of internal airfoil cooling which can delay the use of film cooling resulted in the creation of a new technique which is described in this paper. This technique is based on generation of a swirling flow structure in the blade internal leading edge passage. Significant heat transfer augmentation can be achieved when the cooling air is delivered into the leading edge plenum tangentially to the inner concave surface. The best results can be obtained when the swirling flow is allowed to move radially, creating a three-dimensional screw-shaped flow in the plenum.
The presented results of the flow and heat transfer studies performed for the practical range of Reynolds numbers for the internal flow show that the leading edge screw-shaped cooling technique provides internal heat transfer rate comparable with impingement coupled with film discharge of the spent air, is more effective than impingement with cross flow and is almost five times higher than heat transfer in the smooth channel.
Evaluation of the Effectiveness of a Metal Deactivator and Other Additives in Reducing Insolubles in Aviation Fuels
Authors: Jones E. Grant , Balster Walter J. , Balster Lori M. 
Published: February 2015

Surface fouling in aircraft fuel lines resulting from autoxidation of aviation fuel leads to reduced efficiency as deposits collect on heat exchangers, nozzles, and servocontrols and may ultimately lead to system failure. Metal surfaces and trace quantities of metals dissolved in the fuel exacerbate the surface-fouling problem because they can catalyze free-radical initiation, thereby accelerating autoxidation. Additives and additive packages containing antioxidants, dispersants, and metal deactivators (MDA) have been shown to reduce insolubles in some fuels. Because of metal chelation and possible metal-surface passivation, MDA has been proposed as an additive component to be included in all fuels, even those without dissolved metals. The goal of the present study was to obtain fundamental information on the behavior of MDA under conditions where surface-passivation effects are minimal. Experiments have been conducted to 1) study the effects of adding MDA to fuels containing a significant concentration of dissolved metals (i.e., chelation) and to those containing minor concentrations of dissolved metals and 2) investigate interactions when MDA is used in conjunction with an antioxidant and a dispersant.
Simple fuel-line-fouling simulations with a single-pass tubular heat exchanger operated under near-isothermal conditions have been conducted to study the thermal behavior at 185°C of several neat and MDA-treated jet fuels as well as fuels treated with MDA plus other additives. Comparison of neat and treated fuels is based on several criteria: 1) dependence of autoxidation on stress duration, 2) dependence of surface deposition on stress duration, and 3) quantity of total insolubles (bulk filterables and surface deposits). Potential advantages and disadvantages of using MDA alone and in combination are discussed.
Managing Naval Gas Turbines Through a Memorandum of Understanding
Authors: Markus J. Albert , Glennie Andy M. G. 
Published: February 2015

This paper describes how four European navies have been able to work together for over twenty years in order to support their marine Tyne, Olympus and Spey gas turbines, used for surface ship propulsion, through two internationally agreed Memoranda of Understanding (MOUs).
It shows how the MOUs came into existence, what their main aims are, how they are organised and how MOU business is conducted to achieve these aims.
The final part of the paper discusses the merits of the existing MOUs and presents an insight into how they, and other MOUs currently under discussion, may develop in the future.
Transonic Film-Cooling Investigations: Effects of Hole Shapes and Orientations
Authors: Wittig S. , Schulz A. , Gritsch M. , Thole K. A. 
Published: February 2015

The emphasis of the present study is to understand the effects of various flowfield and geometrical parameters in the nearfield region of a scaled-up film-cooling hole on a flat test plate. The effect of these different parameters on adiabatic wall effectivenesses, heat transfer coefficients, discharge coefficients and the near-hole velocity field will be addressed. The geometrical parameters of concern include several angles of inclination and rotation of a cylindrical film-cooling hole and two different hole shapes — a fanshaped hole and a laidback fanshaped hole. The fluid dynamic parameters include both the internal and external Mach number as well as the mainstream-to-coolant ratios of total temperature, velocity, mass flux, and momentum flux. In particular, the interaction of a film-cooling jet being injected into a transonic mainstream will be studied.
This paper includes a detailed description of the test rig design as well as the measuring techniques. Firstly, tests revealing the operability of the test rig will be discussed. Finally, an outlook of the comprehensive experimental and numerical program will be given.
Cost Effective Manufacturing Methods for Structural Ceramic Matrix Composite (CMC) Components
Authors: Wurtinger H. , Mühlratzer A. 
Published: February 2015

MAN Technologie AG has been engaged in the field of ceramic matrix composites (C/SiC, SiC/SiC) for approximately 10 years. Two manufacturing methods have been developed with respect to economical series production:
- Chemical Vapour Infiltration Process (CVI) with temperature and pressure gradients
- Liquid Polymer Impregnation (LPI) and Pyrolysis
The advantage of these methods is an essential reduction of process time compared to the conventional isothermal-isobaric CVI method, with equivalent material performance. The main material characterization data, such as strength/strain, thermal shock, dynamic fatigue and high temperature behaviour are described. Several components under development or in low volume preseries production are presented.
Inlet Conditioning Enhances Performance of Modern Combined Cycle Plants for Cost-Effective Power Generation
Authors: Van Der Linden Septimus , Searles David E. 
Published: February 2015

This paper will examine the performance enhancement and cost benefits of inlet air conditioning applied to a modern combined cycle plant at high ambients, resulting in lower electricity production costs. Site specific cases are presented to demonstrate a broad range of application and cost benefits.
The successful project in today’s aggressive competitive power marketplace is most typically defined as “lowest $/kW”. Traditional combined cycle plants have been driven to higher levels of efficiency by increasing gas turbine heat recovery using large, multiple pressure level heat recovery steam generators and improving heat sink technologies with aggressive cooling towers or air cooled condensers. This methodology rapidly produced less competitive results as the price of new generation was reduced.
The driving technology behind this change was the development of high output, high efficiency advanced gas turbines. Improved metallurgy, cooling schemes and blade coating systems permitted each GT manufacturer to offer improved output and efficiencies. These improvements, coupled with industry uncertainty due to the threat of deregulation and consequential reduction in new generation opportunities, has allowed new performance standards to be realized for equal or lower unit prices, leading to an unparalleled reduction of installed cost for new power plants.
Analysis of the Oil Film on the Inside Surface of an Aero-Engine Bearing Chamber Housing
Authors: Chew John W. 
Published: February 2015

Knowledge of flow and heat transfer in bearing chambers is important in the design of engine oil systems. In this paper a simplified model of the oil film on the housing of a bearing chamber is presented and the results compared with other workers’ measurements. An integral approach is used and the analysis includes the effects of surface friction, heat transfer, gravity and swirl of the oil at inlet. Two-dimensionality is assumed with variations in the axial direction being neglected. The model is expected to apply at high rotational speeds where “rimming” dominates with the oil flowing around the drum in a continuous film. A similar rimming flow regime occurs in a rotating, horizontal drum partially filled with liquid and the present model is also tested against data for this problem.
Some good qualitative and quantitative agreement with measurements has been found, but significant discrepancies and uncertainties remain. Overall the results of this first attempt to analyse the bearing chamber flow are considered very encouraging.
Ceramics for ATS Industrial Turbines
Authors: Wenglarz Richard , Ali Sy , Layne Abbie 
Published: February 2015

The U.S. Department of Energy and most U.S. manufacturers of stationary gas turbines are participating in a major national effort to develop advanced turbine systems (ATS). The ATS program will achieve ultra-high efficiencies, environmental superiority, and cost competitiveness compared with current combustion turbine systems. A major factor in the improved efficiencies of simple cycle ATS gas turbines will be higher operating temperatures than current engines. These temperatures strain the limits of metallic alloy and flow-path cooling technologies.
Ceramics materials offer a potential alternative to cooled turbine alloys for ATS turbines due to higher melting points than metallics. This paper evaluates ceramics technology and plant economic issues for ATS industrial turbine systems. A program with the objective of demonstrating first-stage ceramic vanes in a commercial industrial turbine is also described.
Computation of the Unsteady Transonic Flow in Harmonically Oscillating Turbine Cascades Taking Into Account Viscous Effects
Authors: Grüber B. , Carstens V. 
Published: February 2015

This paper presents the numerical results of a code for computing the unsteady transonic viscous flow in a two-dimensional cascade of harmonically oscillating blades. The flow field is calculated by a Navier-Stokes code, the basic features of which are the use of an upwind flux vector splitting scheme for the convective terms (Advection Upstream Splitting Method), an implicit time integration and the implementation of a mixing length turbulence model.
For the present investigations two experimentally investigated test cases have been selected in which the blades had performed tuned harmonic bending vibrations. The results obtained by the Navier-Stokes code are compared with experimental data, as well as with the results of an Euler method.
The first test case, which is a steam turbine cascade with entirely subsonic flow at nominal operating conditions, is the fourth standard configuration of the “Workshop on Aeroelasticity in Turbomachines”. Here the application of an Euler method already leads to acceptable results for unsteady pressure and damping coefficients and hence this cascade is very appropriate for a first validation of any Navier-Stokes code. The second test case is a highly-loaded gas turbine cascade operating in transonic flow at design and off-design conditions. This case is characterized by a normal shock appearing on the rear part of the blades’s suction surface, and is very sensitive to small changes in flow conditions. When comparing experimental and Euler results, differences are observed in the steady and unsteady pressure coefficients. The computation of this test case with the Navier-Stokes method improves to some extent the agreement between the experiment and numerical simulation.
A Semiclosed Cycle Gas Turbine With Carbon Dioxide-Argon as Working Fluid
Authors: Ulizar Inaki , Pilidis Pericles 
Published: February 2015

This paper describes the performance analysis of a semi closed cycle gas turbine. The working fluid is carbon dioxide and the fuel is low heating value gas synthesised from coal. The objective of the machine is to produce clean electricity with the smallest efficiency penalty.
Firstly the thermodynamic properties of the gases in the cycle were obtained as a function of temperature and pressure. Then two performance simulation codes were developed. These have the ability of simulating different configurations of open, closed and semi-closed cycles. The first code was used for cycle optimisation and the second for off-design studies.
The design and off-design performance of the machine are predicted. The production of clean electricity will be at the expense of a lower efficiency compared with current equipment. Finally, some critical issues for the development of such a gas turbine are identified.
Development of a High Specific Speed Centrifugal Compressor
Authors: Rodgers C. 
Published: February 2015

This paper describes the development of a subscale single stage centrifugal compressor with a dimensionless specific speed (Ns) of 1.8, originally designed for full size appllcatioa as a high volume flow, low pressure ratio, gas booster compressor. The specific stage is noteworthy in that it provides a benchmark representing the performance potential of very high specific speed compressors of which limited information is found in open literature. Stage & component test performance characteristics are presented together with traverse results at the impeller exit. Traverse test results were compared with recent CFD computational predictions, for a exploratory analytical callbration of a very high specific speed impeller geometry.
The tested subscale (0.583) compressor essentially satisfied design performance expectations with an overall stage efficiency of 74% incinding, excessive exit casing losses. It was estimated that stage efficiency could be increased to 81% with exit casing losses halved.
Characterization of Laws of Friction in the Context of Engine Blade Dynamics
Authors: Srinivasan A. V. , McFarland D. Michael 
Published: February 2015

Experience has shown that energy dissipation due to rubbing at interfaces of engine blade shrouds provides damping of bladed disk assemblies. An accurate estimate of such damping has been a subject of study for more than a decade. The most difficult parameter that influences its accurate calculation pertains to an appropriate definition of the laws of friction that relate the rubbing motion with the forces induced.
This paper develops an analysis which leads to a mathematical relationship between the forces of friction damping at a vibrating interface and the corresponding relative motion. The analysis permits calculation of forces at the interface if the displacements are known or vice versa. The equations are cast in terms of relative motion between mating shrouds so that degenerate cases of fully locked and freely slipping can be calculated. Examples are given showing simulation results obtained using discrete structural models. Extension of the analysis to the case of a full assembly is discussed.
Development of a Cobalt Base Superalloy for Heavy Duty Gas Turbine Nozzles
Authors: Sato M. , Kobayashi Y. , Matsuzaki H. , Shimomura K. , Shibata T. , Nakamura S. , Fukui Y. , Wada K. 
Published: February 2015

This paper describes an improvement in creep strength and thermal fatigue and hot corrosion resistance of a cobalt base superalloy developed for the applications of heavy duty gas turbine nozzles. The developed alloy has superior resistance to creep, thermal fatigue and hot corrosion over that of conventional alloys.
The optimization of alloying elements which improve the creep properties and restrain the coarsening of carbides is discussed. A reduction in the volume fraction of eutectic carbides promoted the prevention of fast thermal fatigue cracking and also increased the hot corrosion resistance of the developed alloy.
The mechanical properties were evaluated by general method for gas turbine materials. Thermal fatigue property was examined by introducing cyclic thermal stress into test pieces. During the test, crack propagation of the test pieces was observed. Hot corrosion resistance was evaluated by molten salt corrosion tests. After tests, mass loss of specimens was measured and penetration depth of sulfidized scale was observed. The developed alloy showed good properties which can allow a wide temperature margin for high temperature gas turbine nozzle designing.
The developed alloy can be applicable to other gas turbine hot sections. Application of the developed alloy could realize an increase in gas firing temperature or extension of lifetime for current conditions.
Modular Approach to Off-Design Gas Turbines Simulation: New Prospect for Reheat Applications
Authors: Carcasci Carlo , Facchini Bruno , Marra Riccardo 
Published: February 2015

This paper proposes the application of a modular approach to off-design prediction of multi- and single-shaft gas turbines. The performance effects of some variations of plant configurations are easy to predict. A solution adopted for module matching is shown, and the instability phenomena in some elementary units (i.e. stalling and surge in the compressor) are studied.
The partial load behavior study of aeroderivative gas turbines is presented and performance comparisons are made with a particular heavy-duty advanced application. An analysis example shows some reheat effects in combined power plant applications.
This work enabled the authors to make interesting observations on control techniques and gas-turbine configurations for advanced, combined power-plants. It also shows the wide possibilities of code applications.
Transonic Probe Blockage Effects in a Calibration Wind–Tunnel and Stator Blade Passage
Authors: Truckenmüller Frank , Renner Martin , Stetter Heinz , Hosenfeld Hans–Georg 
Published: February 2015

Probe blockage effects are presented for transonic flow through a calibration wind–tunnel as well as through a guide vane row in a three–stage model turbine.
Accurate experimental data from measurements in a transonic turbine are needed for the verification of CFD results. The accuracy of etatic pressure measurements in transonic turbine stages is severely affected by the pressure probe stem disturbing the surrounding flow–field. These disturbance effects are present during calibration procedures in wind–tunnels, as well as during measurements in–between turbomachinery blade rows. Therefore, the phenomenon associated with this blockage effect must be investigated for both procedures.
The influence of the blockage ratios on the static pressure readings of the four–hole wedge probe during the calibration procedure is investigated for two different wind–tunnels. The aim is to measure the blockage effects on the blade passage flow which are produced by a pneumatic pressure probe immersed in the flow between two adjacent blade rows. In order to measure these effects, two stator blades are instrumented with static pressure taps along the blade chord, as well as along the blade span. During the investigations, the radial and circumferential positions of the probes relative to the blade channel are varied. Pressure probe readings of two four–hole wedge probes with different stem diameters are compared as well as correlated to the static pressure readings of the stator blade pressure taps. The apparent deviations of the different readings are discussed.
Turbulence Amplification With Incidence at the Leading Edge of a Compressor Cascade
Authors: Hobson Garth V. , Wakefield Bryce E. , Roberts William B. 
Published: February 2015

Detailed measurements, with a two-component laser-Doppler velocimeter and a thermal anemometer were made near the suction surface leading edge of Controlled-Diffusion airfoils in cascade. The Reynolds number was near 700,000, Mach number equal to 0.25, and freestream turbulence was at 1.5% ahead of the cascade.
It was found that there was a localized region of high turbulence near the suction surface leading edge at high incidence. This turbulence amplification is thought to be due to the interaction of the free-shear layer with the freestream inlet turbulence. The presence of the local high turbulence affects the development of the short laminar separation bubble that forms very near the suction side leading edge of these blades. Calculations indicate that the local high levels of turbulence can cause rapid transition in the laminar bubble allowing it to reattach as a short “non-burst” type.
The high turbulence, which can reach point values greater than 25% at high incidence, is the reason that leading edge laminar separation bubbles can reattach in the high pressure gradient regions near the leading edge. Two variations for inlet turbulence intensity were measured for this cascade. The first is the variation of maximum inlet turbulence with respect to inlet-flow angle; and the second is the variation of leading edge turbulence with respect to upstream distance from the leading edge of the blades.
Turbomachinery Multistage Simulation by a Finite Element Adaptive Approach
Authors: Sleiman M. , Robichaud M. P. , Peeters M. F. , Tam A. , Habashi W. G. , Fortin M. 
Published: February 2015

This paper presents the application of a three-dimensional Navier-Stokes finite element code (NS3D) in the context of turbomachinery rotor-stator multistage interaction. A mixing-plane approach is used, in which boundary conditions at a common interface plane between adjacent blade rows are iteratively adjusted to yield a flow satisfying the continuity, momentum and energy conservation equations, in an average sense.
To further improve the solutions, a mesh adaptation technique then redistributes the mesh points of the structured grid within each component, according to an a posteriori error estimate based on the Hessian of the local flow solution. This matrix of second derivatives controls both the magnitude and direction of the required mesh movement at each node, which is then implemented using a spring analogy.
The methodology is demonstrated for the second stage compressor of the UTRC large-scale rotating rig at an rpm of 650 and a flow coefficient of 0.51, and for a two-stage compressor of a turboprop engine running at 45,000 rpm. The results compare well to the experimental data and illustrate the potential of the approach.