bluuebunny/crossref_metadata_2025_split huggingface dataset:
Emissions Reduction by Varying the Swirler Airflow Split in Advanced Gas Turbine Combustors
Authors: Micklow Gerald J. , Roychoudhury Subir , Nguyen H. Lee , Cline Michael C. 
Published: March 2015

A rich burn/quick mix/lean burn (RQL) combustor concept for reducing pollutant emissions is currently under investigation at the NASA Lewis Research Center (LeRC). A numerical study was performed to investigate the chemically reactive flow with liquid spray injection for the RQL combustor. The RQL combustor consists of an airblast atomizer fuel injector, a rich burn section, a converging connecting pipe, a quick mix zone, a diverging connecting pipe and a lean combustion zone. For computational efficiency, the combustor was split into two sub systems, i.e. the fuel nozzle/rich burn section and the quick mix/lean burn section.
The current study investigates the effect of varying the mass flow rate split between the swirler passages for an equivalence ratio of 2.0 on fuel distribution, temperature distribution, and emissions for the fuel nozzle/rich burn section of an RQL combustor. The input conditions used in the study were chosen based on tests completed at LeRC. It is seen that optimizing these parameters can substantially improve combustor performance and reduce combustor emissions. The optimal mass flow rate split for reducing NOx emissions based on the numerical study was the same as found by experiment at LeRC.
Second-Law Analysis of a Compressed Air Energy Storage (CAES) System
Authors: Weiner D. , Shnaid I. 
Published: March 2015

Compressed Air Energy Storage (CAES) system consumes excess energy from base load steam power plant, converts it into stored pneumatic energy and then releases it during peak load period through a gas turbine.
A comprehensive analysis of exergy flows, inputs, outputs and losses in the entire (CAES and steam plant) system is carried out. The irreversible losses and the system efficiency are more realistically presented, than according to the conventional first-law analysis.
Various CAES system schemes and cycle characteristics are studied. It is shown that in some cases the overall thermal efficiency is higher in the combined CAES-Steam Plant System, than in an industrial gas turbine.
Vibration of a Rigid Shaft Supported by Radial Ball Bearings With Several Defects
Authors: Franco J. M. , Akturk N. , Gohar R. 
Published: March 2015

In this paper a vibration analysis of a rigid shaft-ball bearing system has been carried out, in order to approximate the nonlinear load-deformation characteristics of the ball/race contacts, an approximation by means of the Taylor series is studied. The response of an imperfect model system in both time and frequency domains is analyzed. Factors affecting the vibration characteristics of the system such as rotating unbalance, the varying diameter of the balls and the surface waviness are investigated. The vibration analysis of the system, including various external excitations, is carried out for each set of conditions and for more than one defect simultaneously.
It is shown that the mathematical model of the total ball load-deflection relationship has a linear part that depends on the initial deflection, a small time dependent component, the load-deflection coefficient; and a number of terms contributing to nonlinearity of the contact stifness.
Numerical Simulation of the Flow Field Around Supersonic Air-Intakes
Authors: Freskos G. , Penanhoat O. 
Published: March 2015

The demand for efficiency in today’s and in future civil aircraft is such that experimental studies alone do not suffice to optimize aircraft aerodynamics. In this context, much effort has been spent in the past decade to develop numerical methods capable of reproducing the phenomena that occur in the engine flow field.
This paper presents some studies in Computational Fluid Dynamics related to supersonic inlets.
Two approaches are considered. First, there is a need for code capable of calculating in a cost-efficient way the entire flow field around a 2D or 3D inlet, e.g. to perform parametric studies. To this effect, a computing method based on grid construction by mesh generator dedicated to inlet shapes and on the discretization of the unsteady Euler equations with an explicit upwind scheme was developed. The treatment of complex geometries led us to adopt a multiblock grid approach. Therefore particular attention was paid to the treatment of the boundary conditions between the different domains.
Secondly, there is a need for code that can capture local phenomena in order to get a better understanding of inlet behaviour (shock/shock, shock/boundary layer interactions, etc.). To this effect a 2D turbulent Navier-Stokes code is used. The 2 equations k-ε turbulence model included in the program seems to be one of the most successful models for calculating flow realistically. Correction of the near-wall influence extends its capability to complex flow configurations, e.g. those with separated zones.
Calculation of Three-Dimensional Boundary Layers on Rotor Blades Using Integral Methods
Authors: Karimipanah M. T. , Olsson E. 
Published: March 2015

The important effects of rotation and compressibility on rotor blade boundary layers are theoretically investigated. The calculations are based on the momentum integral method and results from calculations of a transonic compressor rotor are presented. Influence of rotation is shown by comparing the incompressible rotating flow with the stationary one. Influence of compressibility is shown by comparing the compressible rotating flow with the incompressible rotating one.
Two computer codes for three-dimensional laminar respectively turbulent boundary layers, originally developed by SSPA Maritime Consulting AB, have been further developed by introducing rotation and compressibility terms in the boundary layer equations. The effect of rotation and compressibility on the transition have been studied. The Coriolis and Centrifugal forces which contribute to the development of the boundary layers and influence its behaviour, generate crosswise flow inside the blade boundary layers, the magnitude of which depends upon the angular velocity of the rotor and the rotor geometry.
The calculations show the influence of rotation and compressibility on the boundary layer parameters. Momentum thickness and shape factor increase with increasing rotation and decrease when compressible flow is taken into account. For skin friction such effects has inverse influences. The different boundary layer parameters behave similarly on suction and pressure side with the exception of the cross-flow angle, the cross-wise momentun thickness and the skin friction factor.
The codes use a nearly orthogonal streamline coordinate system, which is fixed to the blade surface and rotates with the blade.
New Advanced Cooling Technology and Material of the 1500°C Class Gas Turbine
Authors: Matsuzaki H. , Shimomura K. , Fukuyama Y. , Araki T. , Ishii J. , Yamamoto M. , Shibuya S. , Okuhara I. 
Published: March 2015

This paper describes the advanced cooling technology and materials (directionally solidified and single-crystal superalloys) which are considered key technological factors when developing the 1500°C class high temperature gas turbine.
Adopting a 1500°C class gas turbine developed on the basis of the new technology, a combined cycle plant is likely to achieve a plant thermal efficiency of more than 55% (LHV).
Ramjet NOx Emission: Use of a 3D CFD Method for the Combustor Design of a Super/Hyper-Sonic Transport Propulsion System
Authors: David E. , Bauddin C. , Schultz J. L. , Ansart D. , Meunier S. 
Published: March 2015

As part of SNECMA participation in developing the ramjet of Large-scale Japanese Project for “SUPER/HYPER-SONIC TRANSPORT PROPULSION SYSTEM”, an injection system of lean premix type has been studied.
This concept based on a low fuel/air ratio combustion allows a high reduction of NOx emission. Fuel and air mixing must be rapid and homogeneous in order to obtain the full potential of this principle.
For that purpose, a numerical study has been carried out to find the optimal mechanism on carburation homogeneity. Results of a parametric study are presented and show influences of various injection and flame holder systems on air/fuel flow distributions.
Numerical simulations have been performed with the 3D CFD ECRIN code. It is commonly used at SNECMA for combustion analysis. The main features of this code are presented and more particularly the combustion and NOx emission modeling. A comparison of calculated NOx emission indexes with experimental results obtained in a tubular combustor conducts to a good agreement between experiments and computations.
Coal-Water Slurry Testing of an Industrial Gas Turbine
Authors: Wenglarz R. A. , Wilkes C. , Bourke R. C. , Mongia H. C. 
Published: March 2015

This paper describes the first test of an industrial gas turbine and low emissions combustion system on coal-water-slurry fuel. The engine and combustion system have been developed over the past five years as part of the Heat Engines program sponsored by the Morgantown Energy Technology Center of the U.S. Department of Energy (DOE). The engine is a modified Allison 501-K industrial gas turbine designed to produce 3.5 MW of electrical power when burning natural gas or distillate fuel. Full load power output increases to approximately 4.9 MW when burning coal-water slurry as a result of additional turbine mass flow rate.
The engine has been modified to accept an external staged combustion system developed specifically for burning coal and low quality ash-bearing fuels. Combustion staging permits the control of NOx from fuel-bound nitrogen while simultaneously controlling CO emissions. Water injection freezes molten ash in the quench zone located between the rich and lean zones. The dry ash is removed from the hot gas stream by two parallel cyclone separators.
This paper describes the engine and combustor system modifications required for running on coal and presents the emissions and turbine performance data from the coal-water slurry testing. Included is a discussion of hot gas path ash deposition and planned future work that will support the commercialization of coal-fired gas turbines.
Rotor Design for Large Industrial Gas Turbines
Authors: Endres W. 
Published: March 2015

The overall designs of rotors for modern large industrial gas turbines are all very similar; however, the manufacturers have widely different internal designs. Building up the discs and drums to form the rotor is achieved either by a number of different mechanical joining techniques or by welding. In addition the rotor materials, the mechanical integrity, proof testing and critical rotor areas are also discussed. The conflicting design requirements, i.e. for supporting the centrifugal loads, protecting the rotor against the hot gases and warming the rotor during a start-up without excessive thermal stress, lead to very different design solutions. Thus in this paper the stresses, low cycle fatigue and the operational behavior of some typical designs are compared.
The investigation was limited to turbines with moderate pressure ratio (<16) and low cooling air temperatures allowing the rotors to be made of high strength ferritic steels.
The result shows a preference for welded designs with discs of constant stress which are free of holes in the center. Strength, low cycle fatigue and safety aspects, as well as operational advantages like avoidance of vibrations and ease of inspection speak for this solution.
However, all three considered designs are presently being used by different manufacturers and meet all requirements for successful operation.
Meridional Flow Calculation Using Advanced CFD Techniques
Authors: Kiousis P. , Chaviaropoulos P. , Papailiuou K. D. 
Published: March 2015

Working experience on traditional Meridional Flow Solvers has revealed difficulties concerning both convergence and accuracy of the solution. These difficulties have been observed for instance in certain industrial applications where steep gradients of flow and/or geometrical quantities are present. Transonic flow conditions can cause extra difficulties. All these difficulties may be circumvented when advanced CFD techniques are utilized.
A computational tool, suitable for the solution of the Meridional Through Flow equations for Turbomachinery applications is presented. Assuming that the flow is compressible and inviscid the governing equations are obtained using a streamfunction formulation for the pitch-averaged flow equations. Viscous corrections have been incorporated in the inviscid model in terms of flow angle deviation and total pressure losses.
Governing equations, are discretized using body fitted finite difference schemes. An artificial density upwinding scheme assures convergence in the transonic region. Particular attention has been paid to the numerical integration procedure which is based on a preconditioned gradient method (GMRES).
Calculation results for low and high-speed turbomachines are presented and discussed.
Study of Pressurized Fluidized Bed Combustion Combined Cycles With Gas Turbine Topping Cycle
Authors: Bohn D. , Dibelius G. H. , Pitt R. U. , Faatz R. , Cerri G. , Salvini C. 
Published: March 2015

Coal based combined cycles for efficient generation of electricity or cogeneration of thermal and mechanical (electrical) power can be realized making use of Pressurized Fluidized Bed Combustion (PFBC). A draw-back with respect to the efficiency, however, is imposed from the combustion system limiting the temperature to some 850°C. This threshold may be overcome by integrating a high pressure, high temperature gas turbine topping cycle into the process. In a first step, the high pressure, high temperature gas turbine is fired by natural gas, and the exhaust gas of the turbine is fed to the PFB combustor as an oxygen carrier. In a future advanced system, the fuel gas may be provided by an integrated coal gasification process.
A basic reference case has been established based on commercially available gas turbine equipment, hot gas filtration systems as actually tested in various pilot installations, and on a conservative steam cycle component technology. With an ISO gas turbine inlet temperature of 1165°C and an overall compression ratio of 16 up to 30, the entire process yields a net efficiency of some 46% (LHV) and an overall power output of some 750 MW with the gaseous fuel making up for some 50% of the overall energy input. Both the efficiency and the power output have been found rather insensitive with respect to a variation of the overall compression ratio. However, for a non-intercooled compression, an increase of the maximum process pressure would allow for the energy input to be shifted towards coal (and to reduce the natural gas input), and in particular for an elevated PFB combustor pressure considered mandatory for compactness as well as for combustion efficiency including emissions.
The numerous calculations for the design, the optimization and the prediction of part-load operation of complex systems are efficiently performed with a semi-implicit method, the results of which have been checked carefully against those of a more conventional sequential approach and found in good agreement.
Past and Future of Industrial Cogeneration in The Netherlands
Authors: Blok Kornelis , Turkenburg Wim C. 
Published: March 2015

Gas turbine based combined heat and power generation (cogeneration) has developed strongly in the Netherlands in the past twenty years and has the potential to do so also in the future. In this paper the effect of government incentives, both in the past and in the future, is explored.
In the years 1968 through 1988 1200 MW of industrial cogeneration capacity was installed, based primarily on gas turbines technology. This brought total cogeneration capacity to 1800 MW. The amount of electricity generated by private companies tripled in the period 1968 through 1988. In 1988 industrial power generation supplied 37 MJe, which is equal to nearly 15% of the total amount of electricity consumed in the Netherlands.
In the period up to 1978 there was hardly any governmental policy directed towards stimulation of industrial cogeneration. From 1978 onwards a number of stimulating measures have been brought into operation. From an analysis of implementation and effects of government incentives we conclude that the investment grants provided by the government had a considerable effect on the profitability of cogeneration investments. To a lesser extent this was also valid for relatively cheap standby power contracts that were provided by the utilities. However, stimulation of cogeneration only occurred as far as it concerned electricity production for owner consumption. The production of electricity which had to be sold to the utility grid has never been profitable enough from the industrial viewpoint, notwithstanding the provided incentives, like improved buy-back tariffs.
The future potential of industrial cogeneration has been calculated using a computer model in which a simulation and economic optimization is carried out individually for each of the 300 largest industrial plants in the Netherlands. Using this computer model it can be calculated that in principle the cogeneration capacity in the Netherlands can still be doubled. The cogeneration capacity that can be expected to be realized without any government incentive is estimated to be less than 400 MW. The application of investment grants up to 40% can at best double this figure. Carbon taxes of up to $150 per tonne C are somewhat more effective. In order to realize a large part of the ultimate potential stronger policy measures are necessary, which could be regulation which forbids the use of large-scale steam raising in conventional boilers. Without the application of such physical regulation not much may be expected of private industrial investments in cogeneration. However, utility initiatives presented recently hold the promise of realizing a large part of the potential of industrial cogeneration in the Netherlands.
A Combined Experimental and Theoretical Study of Flow and Pressure Distributions in a Brush Seal
Authors: Bayley F. J. , Long C. A. 
Published: March 2015

A relatively simple theory is presented which can be used to model the flow and pressure distributions in a brush seal matrix. The model assumes laminar, compressible, isothermal flow and requires knowledge of an empirical constant: the seal porosity value.
Measurements of the mass flowrate together with radial and axial distributions of pressure were taken on a non-rotating experimental rig. These were obtained using a 122 mm bore brush seal with 0.25 mm radial interference.
The experimental data are used to estimate the seal porosity. Measurements of the pressure distributions along the backing ring and under the bristle tips are discussed. Predicted mass flows are compared with those actually measured and there is reasonable agreement considering the limitations of the model.
A High Speed Capacitance Based System for Gauging Turbomachinery Blading Radius During the Tip Grind Process
Authors: Sheard A. G. , Westerman G. C. , Killeen B. , Fitzpatrick M. 
Published: March 2015

During the manufacture and overhaul of gas turbines it is necessary to ensure that all blades in a stage are of an equal and known length to minimise the loss in performance that arises as a consequence of the clearance between rotor tip and engine casing. Modern compressor and turbine blades are generally loose fitting in their root fixings and only adopt their true working position when running.
In this paper, a new technique for measuring the rotor radius over individual blades is described. The measurement technique utilises a capacitance based clearance measurement system which enables rotor radius to be measured over each blade while spinning fast enough to ensure that the blades are centrifugally loaded into their true working position. The measurement technique is described, as is the system utilised to calibrate and reduce output into engineering units. The mechanical design of the “measurement head” is presented and the CNC lathe to which it interfaces described. Finally, the results of an experimental programme, utilising a fully bladed compressor disc undertaken to ascertain system performance, are presented.
An Automated Flow Line for Gas Turbine Blade Repair
Authors: Doll David B. 
Published: March 2015

The expansion of United Airlines into a global airline has brought with it a substantial increase in the requirements for maintenance support. Existing operations for the repair of shrouded turbine blades were not structured to efficiently repair the increasing volume of unserviceable blades generated by the airline.
The methodology of re-engineering the repair process for shrouded turbine blades in order to generate economies of scale is discussed. The design concepts for an integrated flow line with automated material handling and real time decision making are presented. Operation of the line including manual and automated inspection, automated grinding and welding and manual blending is described. Performance of the line is compared to the prior shop environment, and lessons learned in the accomplishment of the project are discussed.
Second-Order Effects of Unsteadiness on the Performance of Turbomachines
Authors: Fritsch Gerd , Giles Michael 
Published: March 2015

A 2D, linearized approach is used to investigate second-order effects of unsteadiness on the time-mean efficiency of turbomachinery. The objective is to quantify unsteady losses with a nonzero time-mean and to examine numerical simulations with respect to the modeling of unsteady flow fields and loss mechanisms. Results of simulations constitute the input to the analytical models employed.
Two unsteady loss mechanisms, one of inviscid and the other of viscous nature, are considered. The unsteady circulation losses, i.e., the transfer of kinetic energy into the unsteady part of the flow field through vorticity shed at the trailing edge of a blade, was first considered by Keller (1935) and later by Kemp and Sears (1956). The vorticity is shed in response to an unsteady blade circulation and determined from Kelvin’s circulation theorem which is valid in compressible homentropic flow. Use of a numerical simulation to obtain circulation amplitudes avoids the limitations of thin-airfoil theory and yields results more realistic for modern turbomachinery. For the unsteady viscous loss mechanism, i.e., the dissipation in an unsteady boundary layer on the blade surface, Lighthill’s high-reduced-frequency limit (1955) is used to obtain the local velocity distribution in the laminar sublayer and the corresponding time-mean unsteady dissipation. The input to the model is the time-harmonics of the pressure gradient along a blade surface obtained from a simulation. A numerical study of the errors introduced by a departure from the high-reduced-frequency limit is presented. Losses from both sources are found to be small.