bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurements of Combustor Velocity and Turbulence Profiles
Authors: Goebel S. G. , Abuaf N. , Lovett J. A. , Lee C.-P. 
Published: February 2015

The axial and swirl velocity and turbulence profiles downstream of a small-scale combustor were measured using a Laser Doppler Velocimeter. The effects of combustor geometry (nozzle swirl and liner mixing and dilution holes), operating conditions (mass flow and pressure) and combustion were independently examined. For the combustion tests, the combustor exit temperature profiles were also measured with an insertion thermocouple.
The normalized velocity profiles showed no effect of mass flow, pressure or overall velocity on the combustor exit profiles. For the low-swirl fuel nozzle, levels of turbulence were fairly constant without or with combustion. However, with the high-swirl fuel nozzle, the level of swirl decreased as the firing temperature increased (to conserve angular momentum). The effect of swirl reduction could also be seen in the turbulence levels which also decreased. This showed that the mean swirl was generating much of the turbulence. It was also found from testing various combustor geometries that the dilution jets significantly disrupted and thereby reduced the level of swirl exiting from the combustor.
Vibration Prediction and Quality Control of a Centrifugal Impeller
Authors: Hudson Michael , Ballans Geoffrey H. , Georgomanos Soritis 
Published: February 2015

A multi-disciplinary approach was used to investigate and control the vibration of a 1.7MW gas turbine Impeller. Three techniques were used. First, determination of natural frequencies by Spectral Analysis of an impulse on the impeller. Second, Electronic Speckle-pattern Interferometry (ESPI) to assertain the modal shape of each natural frequency. Finally, 3-dimensional finite element analysis (3DFEA) of the whole impeller.
The analyses were synthesized to give an accurate determination of modal shapes and frequencies at test conditions and validate the 3DFEA. Effect of modifications could be predicted with confidence by the 3DFEA.
A single parameter was found which linked dimension to resonant frequency in disc mode vibration. A test was developed which gave a predictive technique for vibration quality control in a production environment.
Computation of Time Linearized Transonic Flow in Oscillating Cascades
Authors: Kahl G. , Klose A. 
Published: February 2015

A method for calculating the quasi-3D unsteady transonic flowfield in oscillating cascades is presented.
The unsteady flow is assumed to be a small, harmonic perturbation of the non-linear steady flow, so that the steady flow problem is decoupled from the unsteady problem. As long as the vibration amplitudes remain moderate, the higher order terms in the governing equations derived under this assumption can be neglected and the describing unsteady flow equations become linear. Thus every frequency component can be calculated separately and the results be obtained by superposition.
For the calculation of the steady state flow, about which the unsteady part is linearized, a finite-volume time-stepping Euler solver is used.
Due to the similarity of the derived time-linear unsteady flow equations and the basic equations for the steady solver, the discretization is almost identical for both solvers. Thus it is possible to use much of the steady code with little modification for the time-linearized unsteady code.
The time-linear unsteady flow equations are solved on a moving grid. This leads to a considerable simplification of the flow tangency boundary condition on the surfaces of the airfoils.
Results obtained for various test cases compare favourably to flat plate theory and time-linearized potential methods as well as to experimental results from the Lausanne standard configurations.
The approach presented is computationally more efficient than nonlinear unsteady Euler time-stepping methods, thus permitting application in the standard design procedure.
Computer Aided Lifetime Evaluation and its Application to Turbines Design and Their Operation
Authors: Kosman G. P. , Chmielniak T. J. , Rusin A. M. 
Published: February 2015

The scope and methodology of the tests of technical condition of heat turbine components are discussed. Particular attention is paid to the problem of computer aided evaluation of the durability of turbine casing, rotor and valves. Components operating at high and variable temperatures are considered. Under such conditions, durability is determined by the creep of the material and by low-cycle fatigue.
The structure and the basic assumptions for the developed system of computer aided turbine components durability evaluation are presented.
As an example of application of the discussed system, selected results of the analysis of the influence of the turbine startup mode on its durability are included. Another example is concerned the evaluation of operation efficiency of thermo-compression bondings in turbines operating under creep conditions.
Application of the LM6000 for Power Generation and Cogeneration
Authors: Casper R. L. 
Published: February 2015

Since its inception in 1989, the LM6000 gas turbine has undergone a series of successful factory tests and several turbines have begun commercial operation. Derived from the CF6-80C2, the LM6000 has been widely accepted for industrial cogeneration and peaking electrical power applications due to its high output power and high simple cycle thermal efficiency. The successful application of GE’s other LM series gas turbines, such as the LM1600, LM2500, and LM5000, for cogeneration use was factored into the development of the LM6000.
This paper provides an update of the LM6000 performance and operating characteristics based upon data recorded in factory tests completed in 1992. In addition, it discusses how the LM6000 can be adapted to meet power generation and cogeneration needs, both today and beyond the year 2000, including conversion to Dry Low NOx combustion technology.
Magnetic Bearing Control of Flexible Shaft Vibrations Based on Multiaccess Velocity-Displacement Feedback
Authors: Petela G. , Botros K. K. 
Published: February 2015

A model of the forced vibrations of a flexible, asymmetric and unbalanced shaft, supported by two magnetic bearings is derived to simulate the effect of different schemes of active control on shaft dynamic behaviour.
Simulation results were compared for several cases of single and multi-access bearing controls, rigid-body-mode only and rigid with flexible mode control, and linear and non-linear bearing responses. It is shown that the multi-access bearing response calculated from the known equation of the stable ROCL (Reduced Order Closed Loop) and based on the direct velocity-displacement feedback, provided the most precise shift in critical frequencies and also reasonable suppression of shaft vibration amplitudes.
The non-linear bearing design was also briefly discussed. The stability analysis showed that stability limits were influenced by more parameters in this case, but no particular advantages were observed in suppression of the vibration amplitudes as compared to the linear case.
Ceramic Stationary Gas Turbine Development
Authors: van Roode Mark , Brentnall William D. , Norton Paul F. , Pytanowski Gregory P. 
Published: February 2015

A program has been initiated under the sponsorship of the Department of Energy (DOE), Office of Industrial Technology, to improve the performance of stationary gas turbines in cogeneration through the selective replacement of metallic hot section parts with uncooled ceramic components. It is envisioned that the successful demonstration of ceramic gas turbine technology, and the systematic incorporation of ceramics in existing and future gas turbines will enable more efficient engine operation, resulting in significant fuel savings, increased output power, and reduced emissions. The program which started in September, 1992, takes an engine of the Solar Centaur family of industrial gas turbines, and modifies the design of the hot section to accept ceramic first stage blades and first stage nozzles, and a ceramic combustor liner. The ceramic materials selected for the blade are silicon nitride, for the nozzle silicon nitride and silicon carbide, and for the combustor liner silicon carbide as well as two continuous fiber reinforced ceramic composites, one with a silicon carbide matrix and another with an oxide matrix.
This paper outlines the approach, conceptual component design, and materials selection for the program.
Flex Cycle Combustor Development and Demonstration
Authors: Harris Mark M. , Marsh David N. , Vos Eduard A. , Durkin Edward 
Published: February 2015

An innovative, “flex-cycle” combustion system has been developed for the Garrett Model 400-1 Integrated Power Unit (IPU), a 425 shp (317 kW) gas turbine engine designed for use on future fighter aircraft. Demonstration of this system required real-time transient operation of the combustor in a full-scale test rig. The transient testing was unique, having been performed with an electronic control which modulated all combustor operating parameters according to programmed engine component maps, drag curves, fuel schedules, and selected ambient test conditions.
The axially-injected annular combustor is capable of engine starts in two seconds, as well as producing 200 shp (149 kW) for emergency use at all altitudes up to 50,000 ft (15.240 m). The combustion system is capable of switching operation from the emergency power stored energy (SE) mode to the normal-air breathing (NAB) auxiliary power mode without loss of engine power. The flex-cycle combustor supplies emergency power in the SE mode with a temperature rise of 2200F (1222C) and in the NAB mode with a temperature rise of 1600F (889C). Specific features which make the above requirements possible include air-assisted simplex airblast fuel atomizers with integral check valves, and effusion-cooled combustor liner walls.
This paper describes the flex-cycle combustion system design, test methods used, and significant test results. Steady-state performance, in both the SE and NAB operating modes, and real-time transient test results are discussed. The transient testing included rapid starts as well as transitions from the SE to NAB operating regimes.
Advanced Transonic Fan Design Procedure Based on a Navier-Stokes Method
Authors: Rhie C. M. , Zacharias R. M. , Hobbs D. E. , Sarathy K. P. , Biederman B. P. , Lejambre C. R. , Spear D. A. 
Published: February 2015

A fan performance analysis method based upon 3D steady Navier-Stokes equations is presented in this paper. Its accuracy is established through extensive code validation effort. Validation data comparisons ranging from a 2D compressor cascade to 3D fans are shown in this paper to highlight the accuracy and reliability of the code. The overall fan design procedure using this code is then presented. Typical results of this design process are shown for a current engine fan design.
This new design method introduces a major improvement over the conventional design methods based on inviscid flow and boundary layer concepts. Using the Navier-Stokes design method, fan designers can confidently refine their designs prior to rig testing. This results in reduced rig testing and cost savings as the bulk of the iteration between design and experimental verification is transferred to an iteration between design and computational verification.
Externally-Fired Combined Cycle Repowering of Existing Steam Plants
Authors: Vandervort Christian L. , Bary Mohammed R. , Stoddard Larry E. , Higgins Steven T. 
Published: February 2015

The Externally-Fired Combined Cycle (EFCC) is an attractive emerging technology for powering high efficiency combined gas and steam turbine cycles with coal or other ash bearing fuels. The key near-term market for the EFCC is likely to be repowering of existing coal fueled power generation units. Repowering with an EFCC system offers utilities the ability to improve efficiency of existing plants by 25 to 60 percent, while doubling generating capacity. Repowering can be accomplished at a capital cost half that of a new facility of similar capacity. Furthermore, the EFCC concept does not require complex chemical processes, and is therefore very compatible with existing utility operating experience.
In the EFCC, the heat input to the gas turbine is supplied indirectly through a ceramic heat exchanger. The heat exchanger, coupled with an atmospheric coal combustor and auxiliary components, replaces the conventional gas turbine combustor. Addition of a steam bottoming plant and exhaust cleanup system completes the combined cycle.
A conceptual design has been developed for EFCC repowering of an existing reference plant which operates with a 48 MW steam turbine at a net plant efficiency of 25 percent. The repowered plant design uses a General Electric LM6000 gas turbine package in the EFCC power island. Topping the existing steam plant with the coal fueled EFCC improves efficiency to nearly 40 percent. The capital cost of this upgrade is 1,090/kW. When combined with the high efficiency, the low cost of coal, and low operation and maintenance costs, the resulting cost of electricity is competitive for base load generation.
Italian Compressor Stations for Gas Storage
Authors: Zampieri Giuliano , Damiani Vanni 
Published: February 2015

In Italy the gas transmission network, more than 23.000 km long, has 21 compressor stations with a total power of 500 MW. Some of the stations are used only for transmission purposes while others can also be used alternately or at the same time to compress gas into storage fields (Fig.1).
Italy has one of Western Europe’s biggest gas reserves in storage fields: in fact the working gas used at the moment is about 12 Gm3 and the gas in place is about 24 Gm3. The total compression capacity is about 90 Mm3/d with discharge pressures of up to 150 bar.
All the stations are remote controlled with no personnel on site. For this, very reliable station control systems are used to control plant, engines and all the station’s auxiliary equipment.
A compressor unit consists of a centrifugal compressor driven by a gas turbine. The heavy duty gas turbines have an output of between 3.7 and 10.4 MW, while the jet derivative turbines have an output of 20.5 MW. The gas compressors have two separate stages (sections) that can be put in series or in parallel according to the required compression ratio and flow.
The special configuration of the stations gas piping is designed to match operating requirements.
Examples of series/parallel configurations of the compressors and of the gas piping are given with an explanation of the pros and cons.
Observations of Wake-Induced Turbulent Spots on an Axial Compressor Blade
Authors: Walker G. J. , Solomon W. J. , Gostelow J. P. 
Published: February 2015

Measurements of transitional flow in regions of strong adverse pressure gradient on an axial compressor stator are reported. The range of observations covers separating laminar flow at transition onset, and reattachment of intermittently turbulent periodically separated shear layers.
Transition was characterised by the regular appearance of turbulent spots in association with the rotor blade wake disturbances. However, the initial breakdown did not coincide with the wake passage as has usually been observed by other workers. The spots rather evolved from the growth of instability wave packets which lagged the wake passage.
Data presented from the compressor blade measurements include: mean and ensemble-average velocities and associated integral parameters; distributions of total, periodic and random disturbance components; typical individual velocity fluctuation records; contours of ensemble-average random disturbance level; and boundary layer intermittency distributions.
Measurements of turbulent intermittency showed a significant fall in this quantity near the wall in the reattaching flow. This has significant implications for the interpretation of transition data from surface film gage observations.
Species Concentrations in a Model Gas Turbine Combustor
Authors: Ghaffarpour M. , Chehroudi B. 
Published: February 2015

To investigate the combustion characteristics of hollow-cone spray flames somewhat similar to those occurring in the primary zone of gas turbine combustion chambers or within oil burners, a swirl-stabilized combustor was designed. The combustor is circular in cross section, with a swirl plate and fuel nozzle axis coinciding with the axes of the combustor. Separate swirl and dilution air flows are distributed into the combustor that pass through honeycomb flow straighteners and screens. A kerosene spray was generated by a simplex atomizer with a nominal initial-spray-angle of 30 degrees. Swirling air with swirl number of 1.5 was produced from a swirl plate. A Phase Doppler Particle Analyzer (PDPA) was used to measure the drop size, mean and rms values of axial drop velocity with and without combustion. Air and fuel flow rates and other conditions were kept identical for reacting and non-reacting cases to investigate effects of combustion alone on the spray. A thermocouple was used to measure the average uncorrected temperature in this turbulent spray flame. A water-cooled stainless-steel gas sampling probe was designed to be used with a gas chromatograph (GC) to measure the gaseous species concentrations in this combustor.
Results for mean axial drop velocity profiles indicate widening of the spray, with slight increase in the magnitudes of the peak drop velocities due to combustion. No measurements of this type are possible inside the hollow-cone spray due to burning of fuel droplets within the flame zone. Root-Mean-Square (RMS) values of drop velocity fluctuations decrease due to combination of increase in gas kinematic viscosity and elimination of small drops at high temperatures. Sauter Mean Diameter (SMD) radial profiles at all axial locations increase with combustion as compared to the no-combustion case due to preferential burning of small drops. At the initial stages of combustion near the atomizer, the gas species concentration changes due to droplet evaporation, decomposition of fuel, reaction, and mixing with extra air. At the end of the visible flame zone, away from the nozzle, no significant amounts of methane and hydrogen have been observed. The gas concentration profiles at this axial position are flat within the burned gas zone. The species concentration profiles measured in the burned gas zone near the nozzle and along the spray centerline axis are similar to those of turbulent gaseous-fuel diffusion flame.
CFD Study of Nozzle Configurations for Ultra High Bypass Engines
Authors: Zimmermann H. , Gumucio R. , Katheder K. , Jula A. 
Published: February 2015

Performance and aerodynamic aspects of ultra-high bypass ratio ducted engines have been investigated with an emphasis on nozzle aerodynamics. The interference with aircraft aerodynamics could not be covered.
Numerical methods were used for aerodynamic investigations of geometrically different aft end configurations for bypass ratios between 12 and 18, this is the optimum range for long missions which will be important for future civil engine applications.
Results are presented for a wide range of operating conditions and effects on engine performance are discussed. The limitations for higher bypass ratios than 12 to 18 do not come from nozzle aerodynamics but from installation effects.
It is shown that using CFD and performance calculations an improved aerodynamic design can be achieved. Based on existing correlations, for thrust and mass-flow, or using aerodynamic tailoring by CFD and including performance investigations, it is possible to increase the thrust coefficient up to 1%.
Experimental Investigations of the Influence of Incoming Wakes on the Losses of a Linear Turbine Cascade
Authors: Ladwig M. , Fottner L. 
Published: February 2015

The objective of this work is to enhance the understanding of the influence of wake induced non-uniform, steady inlet flow conditions on the profile losses of highly-loaded turbines. For different Reynolds numbers wake and profile pressure distribution measurements were carried out on a linear subsonic turbine cascade as well as measurements with a single sensor hot-film probe. The non-uniform inlet flow were simulated with two different cascades of cylindrical bars.
The measurements with various circumferential positions of the incoming wakes relative to the turbine cascade show at low Reynolds numbers a decrease of the losses compared to uniform inlet conditions, because no separation of the suction side boundary layer occurs. With increasing Reynolds numbers the non-uniform inlet flow conditions cause an increase in the losses compared to uniform inlet conditions, due to the forward shift of transition. Generally, the smallest influence of the non-uniform incoming flow can be observed when the wakes enter the cascade inlet plane between the pressure-side of the profiles and the middle of the blade passage. Incoming wakes have the highest influence when they enter the blade passage near to the suction side of the profiles.
The Design and Fabrication of a Small Highly Instrumented Counterrotating Turbine Rig
Authors: Davidson D. P. , Finke A. K. 
Published: February 2015

The paper describes some of the design solutions that were adopted in the realization of a small two shaft, counterrotating turbine rig. The turbine, for a small space engine technology upper stage liquid propellant rocket turbo pump system, was only 100mm tip diameter with a correspondingly small annulus height. Detailed flow measurements were provided by 3 axis actuators at inlet and outlet of the working section. Torque and Power were measured on each shaft using Radio Frequency (R.F.) telemetry torquemeters.
A modular design allowed the rig to be rebuilt rapidly in one and two stage configurations with different blade sets. This enabled the effect of changing turbine configurations to be studied.
Computed Effects of Rim Seal Clearance and Cavity Width on Thermal Distributions
Authors: Ko S. H. , Rhode D. L. , Guo Z. 
Published: February 2015

Axisymmetric solutions of the Reynolds averaged Navier-Stokes equations were obtained for the complete momentum/thermal interaction at the interface between the turbine hot mainstream and rim seal flow regions. Specifically, the 2-D, axisymmetric, fully elliptic form of the equations was solved in order to obtain detailed insight concerning the effect of the rim seal clearance and cavity width on the disk temperature, gap recirculation zone GRZ and rotational drag. The mainstream and purge flow rates, pressures and temperatures were selected to match those of a typical commercial engine. The details of seven generic geometries, consisting of different seal clearance gaps and different cavity widths, for each of several cooling flow rates are analyzed.
Of particular interest is the result that halving the engine nominal axial clearance of the generic rim seal is not sufficient for preventing the appearance of the GRZ. However, reducing this clearance to 25% of the nominal value does prevent its formation, and in that case the coolant flow continues outward along the disk surface through the rim seal region.
In addition, the first-order characteristics of: (a) the heat transport in the rim seal region and (b) the disk temperature rise due to thermal transport via the rim seal (gap) recirculation zone and via disk frictional heating were illuminated. Further, it is concluded that smaller seal clearances are desirable for reducing rotational drag as well as purge flow rates.