bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical and Experimental Analysis of Secondary Flow in Modern State-of-the-Art Low Pressure Guide Vane Rows
Authors: Lindner Ernst 
Published: February 2015

To enhance the performance of the inlet guide vane and the annular duct of a jet engine, a detailed investigation of annular cascades with two different types of turbine guide vane rows is made. The first one is a leaned guide vane with an aspect ratio of two and a half and a transition duct ahead of the vane. To avoid the losses associated to the decelerating transition duct an alternative vane is designed and investigated with the same inlet and exit conditions. In this case the chord of the vane is increased to the effect that the vane begins immediately at the enterance of the diverging annulus and so a continuously accelerated flow is achieved. To maintain a good performance for this configuration a bowed-type vane with an aspect ratio of one is designed.
The aim of the investigation is to obtain detailed informations on the secondary flow behaviour with particular regard to the development of the total pressure losses and the streamwise vorticity of the vortices inside and behind the blade rows. In the first step a three-dimensional, structured, explicit finite-volume flow-solver with a k–ε turbulence model is validated against the measurements, which were made in cross-sections behind the blades. Having proved that the numerical results are very close to the experimental ones, the secondary flow behaviour inside and behind the blade rows is analysed in the second step. By calculating the streamwise vorticity from the numerical results the formation of horse-shoe vortex, passage-vortex and the trailing edge vortex shed is investigated. The differences of the vortical motion and the formation of the total pressure losses between the two configurations of turbine guide vane rows are discussed.
Research and Development of 300kW Class Ceramic Gas Turbine (Development of the Static Ceramic Components for CGT303)
Authors: Murota Mitsuharu , Ohhashi Issei , Ito Yoshiyuki , Arakawa Sadao 
Published: February 2015

As the result of setting the low pressure ratio at 4.5, sizes of the static ceramic components forming the gas passage in CGT303 have been increased, and establishing reliability of these components was thought to be the most important task. So, the heat-cycle tests were conducted, in advance of the engine operation, and improvements have been made on their material and constructions.
After conducting 600 times of the heat-cycle tests, so far, up to the gas temperature of 1200°C, we have succeeded in the engine operation at the turbine inlet temperature of 1200°C Examples of the problems encountered in the test and of the solutions therefore are introduced in this paper.
Ceramic Gas Turbine Technology Development
Authors: Rettler M. W. , Easley M. L. , Smyth J. R. 
Published: February 2015

Under the U.S. Dept. of Energy/National Aeronautics and Space Administration (DOE/NASA) funded Ceramic Turbine Engine Demonstration Project, formerly the Advanced Turbine Technology Applications Project (ATTAP), AlliedSignal Engines is addressing the remaining critical concerns slowing the commercialization of structural ceramics in gas turbine engines. These issues include demonstration of ceramic component reliability, readiness of ceramic suppliers to support ceramic production needs, and development of ceramic design technologies.
The AlliedSignal/Garrett Model 331-200[CT] Auxiliary Power Unit (APU) is being used as a ceramics test bed engine. The first-stage turbine blades and nozzles were redesigned using ceramic materials, employing the design methods developed during the earlier DOE/NASA-funded Advanced Gas Turbine (AGT) and ATTAP programs. Ceramic engine components have been fabricated and are now being evaluated in laboratory engine testing. The fabrication processes for these components will provide the framework for a demonstration of manufacturing process scale-up to the minimum level for commercial viability. The laboratory engine testing is helping to refine the component designs and focus the development of ceramic component technologies. Extended engine endurance testing and field testing in commercial aircraft is planned to demonstrate ceramic component reliability.
Significant progress has been made during 1994. An engine with ceramic turbine nozzles was successfully operated and engine tests in the laboratory are continuing to gather useful data. An engine equipped with ceramic blades was also tested, but blade fractures occurred, interrupting operation. An extensive investigation has identified possible vibration and contact problems. Investigative evaluation efforts are continuing to identify the problem source and determine go-forward plans for ceramic blade development. Component design technologies have progressed in the areas of modeling particle impact pulverization, development of a ceramic hot corrosion environmental life model, and methods for evaluating ceramic contact damage. The planned ceramic manufacturing scale-up was initiated with two ceramics vendors, Norton Advanced Ceramics (East Granby, CT) and AlliedSignal Ceramic Components (Torrance, CA). The scaleup demonstration program is emphasizing improvement of ceramic processing yields and increased production rates.
Work summarized in this paper was funded by the U.S. Dept. of Energy (DOE) Office of Transportation Technologies, as part of the Turbine Engine Technologies Program, and administered by the NASA Lewis Research Center, Cleveland, OH under Contract No. DEN3-335.
Simple Design Methods for the Prediction of Radial Static Pressure Distributions in a Rotor-Stator Cavity With Radial Inflow
Authors: Hart Kenneth J. , Turner Alan B. 
Published: February 2015

Research has been conducted into the effects of component geometry and air bleed flow on the radial variation of static pressure and core tangential velocity in a rotor-stator cavity of the type often found behind the impeller of a gas turbine engine centrifugal compressor.
A CFD code, validated by rig test data for a wide range of rotor-stator axial gaps and throughflows, has been used to generate pressure and velocity data for typical gas turbine operating conditions.
This data has been arranged as a series of simple design curves which relate the rotational speed of the core of fluid between rotor and stator boundary layers, and hence the static pressure distribution, to primary cavity geometry, rotational Reynolds number and bleed throughflow with particular attention to radial inflowing bleeds. Details are provided on the use and limitations of these curves.
Predictions using this method have been compared successfully with measured data from engine test and a compressor test rig, modified to facilitate variable quantity and direction of impeller rear face bleed flow, at typical gas turbine operational power conditions.
Data generated by these curves can be used directly in the design process and to validate integral momentum methods which can provide relatively simple computation of rotor-stator cavity pressure and velocity distributions independently or within air system network programs.
This approach is considered to be a cost and time effective addition to the analytical design process especially if validated CFD code, which can accommodate rotational flows consistently and accurately, is not available.
A Probabilistic Method for the Fatigue Life Assessment of Powder Metallurgy Parts of Aircraft Engines
Authors: Krafft R. , Mosset S. 
Published: February 2015

This paper will present a probabilistic approach developed in order to assess the fatigue life of aircraft engine parts (turbine disks) obtained by powder metallurgy technique. First of all, the main issues will be pointed out and the theoretical principles of the method will be described. Then the design implications and the experimental correlation will be emphasised.
The scale effect is a major concern for the fatigue life assessment of a powder metallurgy part. It no longer allows the designer to directly evaluate the life of a massive part from experimental results based on small specimen fatigue tests as it is done in the classical methodology. In order to correctly describe this scale effect, incubation sites (inhomogeneities like ceramic inclusions) must be characterised. The size of these inhomogeneities and their positions in the part appeared to be the most relevant parameters. Hence the methodology developed at Snecma integrates the scale effect scatter through a binomial probability distribution as well as a temperature and stress dependent life evaluation for each inhomogeneity size and position. The life calculation of a part implies an analysis of its whole volume and surface. An iterative process determines the number of cycles corresponding to a global reliability level requirement for the part. The complete methodology is then validated by comparing the calculated initiation distribution with experimental results on small specimens and test disks.
New Technology Trends for Improved IGCC System Performance
Authors: Anand A. K. , Cook C. S. , Corman J. C. , Smith A. R. 
Published: February 2015

The application of gas turbine technology to IGCC systems requires careful consideration of the degree and type of integration used during the system design phase. Although gas turbines provide the primary output and efficiency gains for IGCC systems, as compared with conventional coal fired power generation systems, they are commercially available only in specific size ranges. Therefore, it is up to the IGCC system designer to optimize the IGCC power plant within the required output, efficiency and site conditions by selecting the system configuration carefully, particularly for air separation unit (ASU) integration incorporated with oxygen blown gasification systems.
An IGCC system, based on a generic, entrained flow, oxygen blown gasification system and a GE STAG 109FA combined cycle has been evaluated with varying degrees of ASU integration, two fuel equivalent heating values and two gas turbine firing temperatures to provide net plant output and efficiency results. The data presented illustrate the system flexibility afforded by variation of ASU integration and the potential performance gains available through the continued use of gas turbine advances. Emphasis is place on system design choices which favor either low initial investment cost or low operating cost for a given IGCC system output.
Fuel Spray Characteristics of Gas Turbine Fuel Injectors at Cold Start Conditions
Authors: Koblish Theodore R. , Fox Theodore G. , Patel Subhash G. , Siddiqui Jamil R. 
Published: February 2015

Engine starting at extremes of cold ambient and fuel temperatures are a concern to both military and commercial operators of jet engines, but the military in particular needs the capability to quick start under very cold conditions. The ongoing worldwide conversion to JP8 fuel is compromising this ability for older engines developed for use on wide-cut JP4 fuel. The greatly reduced volatility and increased viscosity of JP8 fuel significantly impacts fuel spray angle and droplet size at start conditions resulting in over-long and aborted starts in cold climates.
A program was carried out by Pratt & Whitney and Textron Fuel Systems to investigate and improve the spray qualities of a dual orifice pressure atomizing fuel injector of a commonly used military jet engine in the start to low power range. The primary fuel injector portion was modified to produce a finer droplet size and wider spray angle. A hybrid design with an aerating secondary was also tested. Droplet diameter and spray angles were measured to −40°F (−40°C) temperatures. Variations in fuel flow rate and fuel type were also investigated. It was found that cold fuel had an adverse effect on spray qualities for the all pressure atomizing nozzles, but the hybrid injector was less affected and produced superior sprays at all conditions on the primary portion. Improvements in the all pressure atomizing design resulted in lesser but still significant benefits.
Model Based Diagnostics and Prognosis System for Rotating Machinery
Authors: Bankert Raymond J. , Singh Vinod K. , Rajiyah Harindra 
Published: February 2015

A PC-based automated mechanical vibration diagnostic and prognosis system for rotating machinery is under development by integrating AI-expert system-based interpretative capabilities with rotor dynamics based modeling and numerical optimization techniques. Presented here are the details involved while generating a rotor dynamic simulator: A turbine-generator is properly modeled using the finite element approach to compute steady-state response. The bearing stiffness and damping properties are computed by numerically solving the Reynold’s equation. An optimizer software has been interfaced with the rotor dynamics code for the solution of nonlinear unconstrained function minimization. A finite element based closed form approach has been adopted to compute the gradients of the objective function. The model is perturbed by the optimizer to match the results with simulated field measurement.
The model based optimization technique has been demonstrated on a 120 mass, 6 bearing rotor system. After optimization, the responses and mass unbalance converge to their goal (field) values. To date, feasibility studies show encouraging results to differentiate between mass unbalance and misalignment for realistic systems using this methodology.
Design, Part Load and Transient Operation of Combined Cycle Plants With Water Flashing
Authors: Dechamps P. J. 
Published: February 2015

The last decade has seen remarkable improvement in gas turbine based power generation technologies, with the increasing use of natural gas-fuelled combined cycle units in various regions of the world. The struggle for efficiency has produced highly complex combined cycle schemes based on heat recovery steam generators with multiple pressure levels and possibly reheat. As ever, the evolution of these schemes is the result of a technico-economic balance between the improvement in performance and the increased costs resulting from a more complex system.
This paper looks from the thermodynamic point of view at some simplified combined cycle schemes based on the concept of water flashing. In such systems, high pressure saturated water is taken off the high pressure drum and flashed into a tank. The vapour phase is expanded as low pressure saturated steam or returned to the heat recovery steam generator for superheating, whilst the liquid phase is recirculated through the economizer.
With only one drum and three or four heat exchangers in the boiler as in single pressure level systems, the plant might have a performance similar to that of a more complex dual pressure level system. Various configurations with flash tanks are studied based on commercially available 150 MW-class E-technology gas turbines and compared with classical multiple pressure level combined cycles. Reheat units are covered, both with flash tanks and as genuine combined cycles for comparison purposes. The design implications for the heat recovery steam generator in terms of heat transfer surfaces are emphasized.
Off-design considerations are also covered for the flash based schemes, as well as transient performances of these schemes, because the simplicity of the flash systems compared to normal combined cycles significantly affects the dynamic behaviour of the plant.
Novel Compressed Air Energy Storage (CAES) Systems Applying Air Expanders
Authors: Shnaid Isaac , Weiner Dan , Brokman Shimshon 
Published: February 2015

In Compressed Air Energy Storage (CAES) systems, off-peak electric energy is consumed by air compressors that charge CAES reservoirs. During peak load hours, air released from the CAES reservoir expands, producing electric power. Two novel CAES systems, improving their reliability and efficiency, are introduced.
The first system is the CAES Plant Integrated with a Gas Turbine (CAESIGT), in which 40 percent of the power output is produced by a standard gas turbine, and 60 percent by an air expander utilizing compressed air that is preheated by the exhaust gases of the gas turbine. For certain initial parameters of the compressed air, its temperature after expansion becomes lower than the ambient temperature. This cold air can be used as a source for refrigeration of the gas turbine inlet air and for other purposes.
In the CAES system of the second type, multistage expansion of compressed air is applied. Reheating air between expander stages is provided either by refrigerated substances, by heat sources from surroundings, or by non fuel heat sources such as the waste heat from industry, solar ponds, etc.
Thermodynamic and economic analyses of the novel CAES systems are carried out.
Gas Turbine Inlet Air Cooling and the Effect on a Westinghouse 501D5 CT
Authors: Kohlenberger Chuck 
Published: February 2015

The temperature of the air entering a gas turbine prime mover has a dramatic effect on its performance, including output, heat rate, and exhaust gas temperature (EGT). These variations are easily observed in actual operation and by reference to generic gas turbine (GT) performance curves. The gross capacity increase of a GT operating at 40F (8C) inlet compared to operation at 102F (70C) is 28%. The gross reduction in heat rate for this 62F (16.7C) differential is 6%, and the exhaust gas temperature is reduced 5%. Since the overall mass flow through the GT is increased through the cooling process, the added energy available in the heat recovery steam generator (HRSG), is increased 8% The significant improvements in GT output and efficiency which can be achieved by maintaining lower inlet air temperatures encourage the manufacturer, systems engineer, owner, and operator of GT facilities to consider seriously the implementation of a gas turbine inlet air cooling (GTIAC) system.
GTIAC systems have proven to produce some very excellent economic paybacks due to increased power output, EG mass flow, and reduced heat rates. Generic gross performance factors are plotted (See Figure 1) against inlet air temperature compared to International Standards Organization (ISO) conditions.
The Influence of Large Scale, High Intensity Turbulence on Vane Aerodynamic Losses, Wake Growth, and the Exit Turbulence Parameters
Authors: Ames Forrest E. , Plesniak Michael W. 
Published: February 2015

An experimental research program was undertaken to examine the influence of large-scale high, intensity turbulence on vane exit losses, wake growth, and exit turbulence characteristics. The experiment was conducted in a four vane linear cascade at an exit Reynolds number of 800, 000 based on chord length and an exit Mach number of 0.27. Exit measurements were made for four inlet turbulence conditions including a low turbulence case (Tu ≈ 1%), a grid-generated turbulence case (Tu ≈ 7.5%), and two levels of large-scale turbulence generated with a mock combustor (Tu ≈ 12% & Tu ≈ 8%).
Exit total pressure surveys were taken at two locations to quantify total pressure losses. The suction surface boundary layer was also traversed to determine losses due boundary layer growth. Losses were also found in the core of the flow for the elevated turbulence cases.
The elevated free stream turbulence was found to have a significant effect on wake growth. Generally, the wakes subjected to elevated free stream turbulence were broader and had smaller peak velocity deficits. Reynolds stress profiles exhibited asymmetry in peak amplitudes about the wake centerline, which are attributable to differences in the evolution of the boundary layers on the pressure and suction surfaces of the vanes.
The overall level of turbulence and dissipation inside the wakes and in the free stream was determined to document the rotor inlet boundary conditions. This is useful information for assessing rotor heat transfer and aerodynamics. Eddy diffusivities and mixing lengths were estimated using X-wire measurements of turbulent shear stress. The free stream turbulence was found to strongly affect eddy diffusivities, and thus wake mixing. At the last measuring position, the average eddy diffusivity in the wake of the high turbulence close combustor configuration (Tu ≈ 12) was three times that of the low turbulence wake.
A Computational Study of Pressure Effects on Pollutants Generation in Gas Turbine Combustors
Authors: Amin E. M. , Andrews G. E. , Pourkashnian M. , Williams A. , Yetter R. A. 
Published: February 2015

A numerical study of the effect of pressure on the formation of NOx and soot in an axisymmetric 30° counter rotating axial swirler lean low NOx gas turbine combustor has been conducted. This has previously been studied experimentally and this CFD investigation was undertaken to explain the higher than expected NOx emissions. The combustion conditions selected for the present study were 300 deg K inlet air, 0.4 overall equivalence ratio, and pressures of 1 and 10 bar.
The numerical model used here involved the solution of time-averaged governing equations using an elliptic flow-field solver. The turbulence was modelled using algebraic stress modelling (ASM), The Thermo-chemical model was based on the laminar flamelet formulation. The conserved scalar/assumed pdf approach was used to model the turbulence chemistry interaction. The study was for two pressure cases at 1 and 10 bar. The turbulence-chemistry interaction is closed by assumption of a Clipped Gaussian function form for the fluctuations in the mixture fraction. The kinetic calculations were done separately from the flowfield solver using an opposed laminar diffusion flame code of SANDIA. The temperature and species profiles were made available to the computations through look-up tables.
The pollutants studied in this work were soot and NO for which three more additional transport equations are required namely; averaged soot mass fraction, averaged soot particle number density, and finally averaged NO mass fraction. Soot oxidation was modelled using molecular oxygen only and a strong influence of pressure was predicted. Pressure was shown to have a major effect on soot formation.
The Development of a Combustion System for a 110 MW CAES Plant
Authors: Hounslow D. R. , Grindley W. , Loughlin R. M. , Daly J. 
Published: February 2015

The use of stored energy systems is receiving increased attention for power generation and Alabama Electric Co-operative (AEC) have installed a 110 MW Compressed Air Energy Storage (CAES) plant at McIntosh, Alabama.
The plant employs tandem high and low pressure fired expanders with the high pressure combustors operating at 44 atm and the low pressure units at 15 atm. Both are designed to operate with natural gas, or on No. 2 fuel oil, as a standby fuel.
This paper describes the development of both the high and low pressure combustors for this unique application, the testing of prototypes at simulated conditions at up to 8 atm using customised test rigs and the definition of a design for application to the plant.
Problems encountered during the first three years of operation are described and the solutions to overcome these are also presented.