bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Comparison of Commercial CFD Codes for Steady-State Internal Flow Simulation of Gasoline Direct Injection
Authors: Sinclair Jarrod , Abanteriba Sylvester
Published: February 2009

A performance comparison of commercial CFD codes used for single-phase steady-state simulation of the internal flow within gasoline direct injection (GDI) nozzles has been undertaken. The CFD software codes used include AVL Fire 7.3, AVL Fire 8.01 and CFX-TASCflow 2.11. This presents a mix of segregated and coupled solver technology. High-pressure multi-hole and swirl injector models were analyzed at constant needle-lift values. The comparison focused on software capability, quality and steadiness of solution, calculation time taken, and the ability to streamline the problem solving methodology. Quantitative experimental results were not considered in the analysis due to the numerical nature of the investigation. It was seen that each CFD code produced similar flow fields and overall mass-flows. Results indicated that the steady-state solvers (Fire 8.01 and TASCflow 2.11) were able to decrease computation time significantly, by factors of 2 to 10 compared with the transient time-marching solver Fire 7.3. Further, TASCflow 2.11 was seen to be most appropriate for steady-state internal flow GDI simulations as it resolved the flow fields much quicker than the other codes due to a coupled solver. The multi-hole injector was seen to exhibit steady behavior using each CFD code, while the swirl injector presented some oscillations in the flow field, particularly for TASCflow 2.11. However, the use of single-phase steady-state solvers were found to be highly useful for engineering development of GDI, as it provides engineers with a quick parametric snapshot of the flow behavior, and can aid in the prediction of fuel spray patterns.
Development of a Second Generation In-Flight Icing Simulation Code (Keynote)
Authors: Habashi Wagdi G. , Beaugendre He´loi¨se , Morency Franc¸ois
Published: February 2009

Two-dimensional and quasi-3D in-flight ice accretion simulation codes have been widely used by the aerospace industry for the last two decades as an aid to the certification process. Such codes predict 2-D sectional ice shapes, which are then manufactured from a light material and attached as disposable profiles on a test aircraft to investigate it for stability and control under icing encounters. Although efficient for calculating ice shapes on simple geometries, current codes encounter major difficulties or simply cannot simulate ice shapes on truly 3D geometries such as nacelles, high-lift wings, engines and systems that combine external and internal flows. Modern Computational Fluid Dynamics (CFD) technologies can overcome many of these difficulties and FENSAP-ICE is such a second generation CFD-based in-flight icing simulation system, bringing to the icing field simulation methods already by the aircraft and turbomachinery industries. It is built in a modular and interlinked fashion to successively solve each of flow, impingement, accretion, heat loads and performance degradation via field models based on the Euler/Navier-Stokes equations for the clean and degraded flow, and new partial differential equations for the other three icing processes. This paper presents the FENSAP-ICE system and shows examples of its use.
F-22/F119 Propulsion System Ground and Flight Test Analysis Using Modeling and Simulation Techniques
Authors: Malloy Donald J. , Webb Allan T. , Kidman David S.
Published: February 2009

This paper describes the teaming strategy between the U. S. Air Force’s two major propulsion test centers, Arnold Engineering Development Center (AEDC) and the Air Force Flight Test Center (AFFTC), to employ new modeling and simulation (M&S) techniques to reduce test cost and cycle time. With the long-term goal of developing joint ground/flight modeling and simulation capabilities, AEDC and AFFTC have teamed to apply these data analysis tools to two major propulsion flight test programs, the F-22 and the Joint Strike Fighter (JSF). The emphasis of this paper is on the development and application of a non-linear aerothermodynamic component-level model that serves as the basis for the model-based analysis and fault identification process. Model-to-data comparisons and model-based fault detection and analysis results for F-22/F119 propulsion ground and flight test are also presented for a variety of flight conditions.
An Engine Research Program Focused on Low Pressure Turbine Aerodynamic Performance
Authors: Castner Raymond , Chiappetta Santo , Wyzykowski John , Adamczyk John
Published: February 2009

A comprehensive test program was performed in the Propulsion Systems Laboratory at the NASA Glenn Research Center, Cleveland Ohio using a highly instrumented Pratt and Whitney Canada PW 545 turbofan engine. A key objective of this program was the development of a high-altitude database on small, high-bypass ratio engine performance and operability. In particular, the program documents the impact of altitude (Reynolds number) on the aero-performance of the low-pressure turbine (fan turbine). A second objective was to assess the ability of a state-of-the-art CFD code to predict the effect of Reynolds number on the efficiency of the low-pressure turbine. CFD simulation performed prior and after the engine tests will be presented and discussed. Key findings are the ability of a state-of-the art CFD code to accurately predict the impact of Reynolds number on the efficiency and flow capacity of the low-pressure turbine. In addition the CFD simulations showed the turbulence intensity exiting the low-pressure turbine to be high (9%). The level is consistent with measurements taken within an engine.
A Test Stand for Dynamic Characterization of Oil-Free Bearings for Modern Gas Turbine Engines
Authors: Swanson Erik E. , Walton James F. , Heshmat Hooshang
Published: February 2009

A multi-purpose rotor-bearing dynamic simulator was designed and fabricated for the purpose of experimentally evaluating and validating performance of advanced oil-free and back-up bearings under realistic dynamic conditions. The rotor-bearing dynamic test rig is capable of operation to 25,000 RPM, has a 54 kg test rotor, is designed to simulate a medium size aero gas turbine engine rotor, and incorporates an electromagnetic loader/shaker capable of applying both static and dynamic loads to the rotating shaft. Testing was completed with the rotor fully supported by magnetic bearings, compliant foil bearings, hybrid foil/magnetic and Zero Clearance Auxiliary Bearings. These tests demonstrated numerous advances in oil-free bearing technology. The first ever achievements include: operation of a rotor with a mass in excess of 50 kg supported solely by foil bearings, operation of hybrid foil/magnetic bearings to high speed, continued operation following simulated magnetic bearing failures for a fully hybrid foil/magnetic bearing support system, and operation of a rotor supported solely by Zero Clearance Auxiliary Bearings. Data from several tests of the bearing systems are presented.
Ejector Pumping Enhancement Through Pulsing Primary Flow
Authors: Vermeulen P. J. , Ramesh V. , Miller D. N. , Yagle P. J. , Bender E. E.
Published: February 2009

Computational Fluid Dynamics analysis for a novel pulsed-ejector showed that the pumping effectiveness (ratio of secondary (entrainment) to primary mass flow rate) was significantly increased relative to the unpulsed ejector, and that this was optimized by pulsing at off-resonance (3250 Hz) to the fundamental (2000 Hz) of the ejector. Testing of a novel model pulsed-ejector confirmed strong response for pulse frequencies less than half of the fundamental frequency of about 746 Hz. Acoustic driver frequency response limitations only allowed testing at less than the experimental fundamental frequency. Specifically pumping effectiveness was increased by up to five times, and even more in suction performance, for only 150 W electrical power at the acoustic driver input. Optimum performance was at a frequency of about 250 Hz, and the acoustic drive produced a small but significant increase in the flow stagnation pressure. The results demonstrate important research potential for the novel pulsed-ejector.
Effects of Flow Control on Forced Response and Performance of a Transonic Compressor
Authors: Bailie S. Todd , Ng Wing F. , Wicks Alfred L. , Copenhaver William W.
Published: February 2009

The main contributor to the high-cycle fatigue of compressor blades is the response to aerodynamic forcing functions generated by an upstream row of stators or inlet guide vanes. Resonant response to engine order excitation at certain rotor speeds is especially damaging. Studies have shown that flow control by trailing edge blowing (TEB) can reduce stator wake strength and the amplitude of the downstream rotor blade vibrations generated by the unsteady stator-rotor interaction. In the present study, the effectiveness of TEB to reduce forced blade vibrations was evaluated in a modern transonic compressor rig. A row of wake generator (WG) vanes with TEB capability was installed upstream of the rotor, which was instrumented with strain gages. Data was collected with and without TEB at various rotor speeds involving resonance crossings. Using 0.8% of the compressor core flow for TEB along the full WG-span, rotor blade strain was reduced by 66% at the first torsional resonance crossing. Substantial reductions were also achieved with only partial span TEB. The results demonstrate the effectiveness of the TEB technique for reducing rotor vibrations in the complex flow environment of a closely-spaced transonic stage row. Moderate increases in stage performance were also measured.
Feedstock Blending of Domestic Fuels in Gasifier/Liquifiers
Authors: Green Alex E. S. , Sankar M. S. , Venkatachalam P.
Published: February 2009

In early studies addressing national energy/environmental (EE) problems we concluded that co-utilization of domestic fuels can significantly reduce national reliance on imported fuels, mitigate NOx, SOx, CO2 and other undesirable emissions and provide valuable waste disposal services. Co-firing of coal and biomass for steam turbine power generation is a near-term co-utilization approach that can make use of existing facilities with relatively minor modifications. However, co-gasification by providing fuel for more efficient combustion turbines and fuel cells and co-liquification to produce transportation fuels have greater long-term EE potential. The development of optimum thermo-chemical co-conversion systems can be fostered by developing a common systematics for the pyrolysis of biomass and coal. Towards this goal we have used the large data bases from ASTM standard ultimate and proximate analyses for all fuels along natures coalification path from biomass to peat, lignite, bituminous and anthracite coal. With this composite data we find systematics in the weight percentages of carbon, hydrogen, total volatiles, fixed carbon and feedstock HHVs vs the weight percentage of oxygen. To meet the need for knowledge of the volatile constituents we have used sparsely available slow pyrolysis data in the literature and our own data to further develop a plausible semi-empirical model (SEM) that relates feedstock and product compositions. We here extend these analytic correlations to lower temperatures with the help of CCTL measurements of yields from the pyrolysis of rice hulls. We have recently applied this SEM to exam the systematic yields of a short list (SL) of products (five gases and five liquids) vs [O], the weight percentage of oxygen in the feedstock. Here anchored to the rice hull data we use our analytical relationships to estimate the yields of a long list (LL) of products including many organic compounds that are known to be slow pyrolysis products of coals and biomass. These relations are put forth as a heuristic challenge to ourselves and to specialists in biomass and coal pyrolysis to obtain more and better data and to seek improved engineering formulas that are needed to advanced co-utilization technology. Then energy debtor nations could utilize all of their available domestic fuels, including opportunity fuels, to mitigate their national EE problems. These preliminary results point to a path towards the development of a co-utilization science and technology for optimizing feedstock blends in many co-firing, co-gasifying or co-liquifying applications.
Co-Gasification Study and Optimisation of Coal, Biomass and Plastics Waste Mixtures
Authors: Andre´ Rui Neto , Pinto Filomena , Franco Carlos , Tavares Celestino , Dias Ma´rio , Gulyurtlu I. , Cabrita I.
Published: February 2009

The continuous grow of world population has led to a substantial increase in energy demand. On the other hand, it has given rise to generating large amounts of wastes, which need to be disposed of without any damage to the environment. Such scenario has led to the idea of studying the application of gasification technology to mixtures of coal and wastes. The results obtained so far are encouraging, as they have shown that it is possible to co-gasify coal mixed with either pine or polyethylene wastes to values up to 40% (w/w) of wastes, being even possible to substitute one waste type by the other, whenever their availability are seasonal affected. However, the presence of PE wastes favoured the release of hydrocarbons, which may be reduced by either an increase in gasification temperature or in air flow.
Investigation of Ammonia Formation During Gasification in an Air Blown Spouted Bed
Authors: Paterson N. , Zhuo Y. , Dugwell D. R. , Kandiyoti R.
Published: February 2009

High NH3 concentrations were measured in the fuel gas produced by a pilot scale, air blown gasifier that was operated by British Coal. A laboratory scale gasifier has subsequently been developed to investigate the reactions that produce these potentially high concentrations. It has been found that in addition to the NH3 formed through pyrolytic processes, the introduction of steam (or H2 produced by its decomposition) increases the amount formed. The latter reaction produced the higher proportion of the total NH3. The effect of the gasifier operating conditions on the amount of NH3 formed has been studied. The main control options to minimise the NH3 formed are using an alternative method of bed temperature control (i.e. avoid the use of steam), operating with higher bed temperatures and operation at lower pressures.
Gasification Tests With Sewage Sludge and Coal/Sewage Sludge Mixtures in a Pilot Scale, Air Blown, Spouted Bed Gasifier
Authors: Paterson N. , Reed G. P. , Dugwell D. R. , Kandiyoti R.
Published: February 2009

A series of tests have been done in a pilot scale air blown gasifier, to assess the performance of sewage sludge pellets and sewage sludge pellet/coal mixtures. The aim has been to compare the performances with that achieved with coal alone and to assess the suitability of the sewage containing fuel as a candidate fuel for the Air Blown Gasification Cycle (ABGC). The co-gasification of sewage sludge with coal raised both the CV of the fuel gas and the fuel conversion compared with values achieved with coal alone. The mixtures were operated under very similar conditions to those needed with coal and no adverse operational problems were encountered. A lower fluidising velocity was needed with the neat pellets to enable a stable bed height to be achieved. However, the conversion of the pellets to gas was very high and the fuel gas CV was higher than that achieved during the co-gasification tests. Overall, the results suggest that sewage based materials are suitable for use in the ABGC and that their use can improve the process performance.
Analysis of Indirectly Fired Gas Turbine for Wet Biomass Fuels Based on Commercial Micro Gas Turbine Data
Authors: Elmegaard Brian , Qvale Bjo̸rn
Published: February 2009

The results of a study of a novel gas turbine configuration is being presented. In this power plant, an Indirectly Fired Gas Turbine (IFGT), is being fueled with very wet biomass. The exhaust gas is being used to dry the biomass, but instead of striving to recover as much as possible of the thermal energy, which has been the practice up to now, the low temperature exhaust gases after having served as drying agent, are lead out into the environment; a simple change of process integration that has a profound effect on the performance. Four different cycles have been studied. These are the Simple IFGT fueled by dry biomass assuming negligible pressure loss in the heat exchanger and the combustion chamber, the IFGT fueled with wet biomass (Wet IFGT) assuming no pressure losses, and finally both the Simple and the Wet IFGT incorporating typical data for pressure losses of commercially available micro turbines. The study shows that the novel configuration, in which an IFGT and a drying unit have been combined, has considerable merit, in that its performance exceeds that of the currently available methods converting wet biomass to electric power by a factor of five. The configuration also has clear advantages with respect to corrosion and to the environmental friendliness and the quantity of the waste products and their usefulness.
Benefiting From the Wide Fuel Capability of Gas Turbines: A Review of Application Opportunities
Authors: Moliere Michel
Published: February 2009

Gas Turbines accept a wide range of alternative fuels in connection with the most diverse economy branches, including industry (coal; oil and gas; refining; petrochemistry; steel and mining activities) and, more recently, agriculture (biofuels). This fuel flexibility enhances the other qualities demonstrated by Gas Turbines among which the prominent ones are: energy effectiveness, operational reliability and emission compliance. Therefore, Gas Turbines using local fuel resources and deployed in simple or combined cycles or in cogeneration plants, enable the concept of cost-effective and environmentally-conscious power projects and can make a valuable contribution to the sustainable, regional development. However, in order to benefit from the fuel flexibility of Gas Turbines, some basic technical considerations are necessary. The paper intends to provide the power community with comprehensive information about alternative GT fuels. It offers a review of the main alternative fuel candidates and sets out the primary technical/engineering considerations that underlie their safe and reliable utilization. Special emphasis is placed on: (i) volatile fuels (naphtha, NLG, condensates); (iii) weak gas fuels from the coal/iron industry (coal-bed; coke-oven, blast furnace gas); (iv) paraffin-rich and hydrogen-rich by-products from refineries (‘fuel gas’; LPG) and (iv) ash-forming oils (residuals; heavy crude’s).
Turbofan Performance Deterioration Tracking Using Non-Linear Models and Optimization Techniques
Authors: Mathioudakis K. , Kamboukos Ph. , Stamatis A.
Published: February 2009

A method of identifying the gradual deterioration in the components of jet engines is presented. It is based on the use of an engine model which has the capability to adapt component condition parameters, so that measured quantities are matched. The main feature of the method is that it gives the possibility to identify performance deviations in a number of parameters larger than the number of measured quantities. This is achieved by optimizing a cost function which incorporates not only measurement matching terms but also terms expressing various constraints resulting from the physical knowledge of the deterioration process. Time series of data representing deterioration scenarios are used to demonstrate the method’s capabilities. The test case considered is a twin spool partially mixed turbofan, representative of present day large civil aero engines. Implementation aspects, related to both the measurement set and the identification algorithms are discussed. An interpretation of the output of the method in function of different parameters entering the diagnostic problem is presented.
Automated Fault Diagnosis for Small Gas Turbine Engines
Authors: Davison Craig R. , Birk A. M.
Published: February 2009

In one possible model of distributed power generation a large number of users will operate individual, gas turbine powered, cogeneration systems. These systems will be small, relatively inexpensive, and installed in locations without ready access to gas turbine maintenance experts. Consequently an automated method to monitor the engine and diagnose its health is required. To remain compatible with the low cost of the power system the diagnostics must also be relatively inexpensive to install and operate. Accordingly a minimum number of extra sensors should be used and the analysis performed by a common personal computer system. The current work automates the diagnosis of component faults by comparing the engine’s operating trends to the trends for known faults. This allows the relative percentage chance of each fault occurring to be determined. The likelihood of each fault is then compared, to determine which component is degrading. The technique can be adapted to compare the engines historic operating trend or a single operating point. In this initial work a computer model was used as a test bed and 5 faults were introduced individually. The technique successfully diagnosed the faulty component using either the operating trend or a single operating point.
Increasing Diagnostic Effectiveness by Inclusion of Fuel Composition and Water Injection Effects
Authors: Mathioudakis K. , Aretakis N. , Tsalavoutas A.
Published: February 2009

The paper presents an analysis of the effect of changing the fuel on the performance of industrial gas turbines and examines the impact of such a change on methods used for engine condition assessment and fault diagnostics. A similar analysis is presented for the effects of water injection in the combustion chamber (which is usually done for reducing NOx emissions). First, the way of incorporating the effect of fuel changes and water injection into a computer model of gas turbine performance is described. The approach employed is based on the change of (a) working fluid properties, (b) turbomachinery components performance. The model is then used to derive parameters indicative of the “health” of a gas turbine and thus diagnose the presence of deterioration or faults. The impact of ignoring the presence of an altered fuel or injected water is shown to be of a magnitude that would render a diagnostic technique that does not incorporate these effects ineffective. On the other hand, employing the appropriate physical modeling makes the diagnostic methods robust and insensitive to such changes, being thus able to provide useful diagnostic information continuously during the use of a gas turbine.
The Use of Expert Systems for Gas Turbine Diagnostics and Maintenance
Authors: Spina P. R. , Torella G. , Venturini M.
Published: February 2009

In the paper, Expert Systems (ESs) developed to support gas turbine engine maintenance and diagnostics are presented. The ESs are applied to turbofans and Auxiliary Power Units and are developed both in procedural (Visual Basic) and declarative (Turbo Prolog) languages. The paper reports some examples of ES utilization, so highlighting high interactivity and user-friendly interface. Moreover, for each ES, the main working features as well as strong and weak points are put into evidence.
Upgrading Engine Test Cells for Improved Troubleshooting and Diagnostics
Authors: Roemer Michael J. , Orsagh Rolf F. , Kacprzynski Gregory J. , Scheid James , Friend Richard , Sotomayer William
Published: February 2009

Upgrading military engine test cells with advanced diagnostic and troubleshooting capabilities will play a critical role in increasing aircraft availability and test cell effectiveness while simultaneously reducing engine operating and maintenance costs. Sophisticated performance and mechanical anomaly detection and fault classification algorithms utilizing thermodynamic, statistical, and empirical engine models are now being implemented as part of a United States Air Force Advanced Test Cell Upgrade Initiative. Under this program, a comprehensive set of real-time and post-test diagnostic software modules, including sensor validation algorithms, performance fault classification techniques and vibration feature analysis are being developed. An automated troubleshooting guide is also being implemented to streamline the troubleshooting process for both inexperienced and experienced technicians. This artificial intelligence based tool enhances the conventional troubleshooting tree architecture by incorporating probability of occurrence statistics to optimize the troubleshooting path. This paper describes the development and implementation of the F404 engine test cell upgrade at the Jacksonville Naval Air Station.
Application of Markov Chains to Identification of Turbine Engine Dynamic Models
Authors: Arkov V. Yu. , Kulikov G. G. , Breikin T. V.
Published: February 2009

The paper addresses the problem of dynamic modelling of gas turbines for condition monitoring purposes. Identification of dynamic models is performed using a novel Markov chain technique. This includes identifiability analysis and model estimation. When identifying the model, experimental data should be sufficiently informative for identification. So far, identifiability analysis is weak formed and workable solutions are still to be developed. A possible technique is proposed based on non-parametric models in the form of controllable Markov chains. The second step in systems identification is the model estimation. At this stage, Markov chains are introduced to provide more functionality and versatility for dynamic modelling of gas turbines. The Markov chain model combines the deterministic and stochastic components of the engine dynamics within a single model, thus providing more exact and adequate description of the real system behaviour and leading to far more accurate health monitoring.
A Model-Based Controller for Commercial Aero Gas Turbines
Authors: Turevskiy Arkadiy , Meisner Richard , Luppold Robert H. , Kern Ronald A. , Fuller James W.
Published: February 2009

This article describes the design and development of a model-based control system for a large commercial aero gas turbine engine. The control system, referred to as the Integrated Margin Management (IMM) control, exploits a real-time engine model (RTEM) to estimate control loop feedback signals, enabling the implementation of nontraditional control modes. These nontraditional control modes include algorithms for controlling, optimizing, and/or trading off margins to key operational limits such as thrust, compressor stability, combustor stability, turbine life, redline limits, and emissions. An overview of the results produced with the IMM controller design illustrates the feasibility of this approach for commercial aero gas turbine applications.
Active Combustion Instability Control With Spinning Valve Actuator
Authors: Barooah Prabir , Anderson Torger J. , Cohen Jeffrey M.
Published: February 2009

Active combustion control has been accomplished in many laboratory and real-world combustion systems by fuel modulation as the control input. The modulation is commonly achieved using reciprocating flow control devices. These demonstrations have been successful because the instabilities have been at relatively low frequencies (∼200 Hz) or the scale of demonstration has been small enough to require very small levels of modulation. A number of real-world instabilities in gas turbine engines involve higher frequencies (200–500 Hz) and attenuation requires the modulation of large fractions of the engine fuel flow rate (hundreds of pounds per hour). A spinning drum valve was built to modulate fuel for these applications. Tests showed that this device provided more than 30% flow modulation up to 800 Hz for liquid fuel flows of greater than 400 lbm/hr. This paper describes the performance of the valve in flow bench tests, open-loop forcing and closed-loop instability control tests. The closed loop tests were done on a single-nozzle combustor rig which exhibited a limit-cycling instability at a frequency of ∼280 Hz with an amplitude of ∼7 psi. It also encounters an instability at 575 Hz under a different set up of the rig, though active control on that instability has not been investigated so far. The test results show that the spinning valve could be effectively used for active instability control, though the control algorithms need to be developed which will deal with or account for actuator phase drift/error.
Thermocouple Probes for Accurate Temperature Measurements in Short Duration Facilities
Authors: Paniagua G. , De´nos R. , Oropesa M.
Published: February 2009

Due to the transient operation of short duration facilities (0.2–1.0s running time), fidelity in temperature reproduction requires both minimum steady-state errors and a frequency response above 20Hz. Even with the smallest thermocouple wire diameter (∼12μm), badly designed probes may suffer from unsteady heat conduction between wires and supports. The resulting error is often much larger than steady errors such as the effect of recovery factor. In this paper, the origins of steady and unsteady measurement errors are described and evaluated. An analytical modeling of the transient convection/conduction problem is presented. A number of probe designs are described and evaluated at different Reynolds number. The dynamic response is tested in a hot jet apparatus that generates temperature steps, with jet velocities up to 150m/s. The influence of the length/diameter ratio, the type of support and the presence of a shield on the dynamic response are addressed. The unsteady behavior of a thermocouple probe can be replicated with a combination of first order systems, which defines the transfer function of the probe. The relevant parameters are found by using an optimization routine that fits the numerical system response to the experimental response. This numerical model can be reversed to perform a frequency compensation of the measured data.
An Optimized Pneumatic Probe for Investigation of Gas Turbine Aerodynamics in Full Scale Gas Turbines
Authors: Warnack Dieter
Published: February 2009

In this paper an optimized probe based on in house experience and literature studies for use in full scale gas turbines for power generation is presented. The main advantages of its design are the insensitivity of the probe head to unsteady wakes of blades, its high strength and suitability for high temperatures. Furthermore it is shown that the calibration function is unambiguous. The second part of the paper deals with correction methods for comparison to numerical methods such as difference in position, mass flow, bending of the probe and blockage effects. The methods are discussed by means of examples.
Considerations for Using 3D Pneumatic Probes in High Speed Axial Compressors
Authors: Coldrick Simon , Ivey Paul , Wells Roger
Published: February 2009

This paper describes preparatory work towards three dimensional flowfield measurements downstream of the rotor in an industrial, multistage, axial compressor, using a pneumatic pressure probe. The probe is of the steady state four hole cobra probe type. The design manufacture and calibration of the probe is described. CFD calculations have been undertaken in order to assess the feasability of using such a probe in the high speed compressor environment where space is limited. This includes effects of mounting the probe in close proximity to the downstream stator blades and whether it is necessary to adjust the calibration data to compensate for these effects.
Innovative Minimally Intrusive Sensor Technology Development for Versatile Affordable Advanced Turbine Engine Combustors
Authors: Goldstein Neil , Arana Carlos A. , Bien Fritz , Lee Jamine , Gruninger John , Anderson Torger , Glasheen W. Michael
Published: February 2009

The feasibility of an innovative minimally intrusive sensor for monitoring the hot gas stream at the turbine inlet in high performance aircraft gas turbine engines was demonstrated. The sensor uses passive fiber-optical probes and a remote readout device to collect and analyze the spatially resolved spectral signature of the hot gas in the combustor/turbine flowpaths. Advanced information processing techniques are used to extract the average temperature, temperature pattern factor, and chemical composition on a sub-second time scale. Temperatures and flame composition were measured in a variety of combustion systems including a high pressure, high temperature combustion cell. Algorithms for real-time temperature measurements were developed and demonstrated. This approach should provide a real-time temperature profile, temperature pattern factor, and chemical species sensing capability for multi-point monitoring of high temperature and high pressure flow at the combustor exit with application as an engine development diagnostic tool, and ultimately, as a real-time active control component for high performance gas turbines.
Observations of Flame Behavior in a Laboratory-Scale Pre-Mixed Natural Gas/Air Gas Turbine Combustor From PLIF Measurements of OH
Authors: Hedman Paul O. , Fletcher Thomas H. , Graham Stewart G. , Timothy G. Wayne , Flores Daniel V. , Haslam Jason K.
Published: February 2009

The objective of this study was to obtain instantaneous planar laser induced fluorescence (PLIF) images of OH in a laboratory-scale, gas-turbine combustor (LSGTC) with a pre-mixed, swirl-stabilized, natural gas flame. Instantaneous PLIF images of OH were obtained at each of four operating conditions (high swirl and medium swirl at fuel equivalence ratios of 0.80 and 0.65). Comparison of the instantaneous images illustrates the stochastic nature of the flame structure. Pixel by pixel statistical analysis of each collection of images allowed both mean and standard deviation images to be generated, and analysis at selected locations has allowed probability density functions to be obtained in various regions of the flame structure. PLIF images of OH, along with visual photographs and video recordings, showed a wide variation in flame structure for the different operating conditions. The variations in flame shapes are primarily a result of the effect of the swirl intensity and fuel equivalence ratio. Changes in the airflow rate over an order of magnitude do not seem to affect the visual flame structure in this experiment. Operation at φ = 0.80 produced the most stable flames with both injectors. The flame with the high swirl injector was more coalesced and closer to the injector than with the medium swirl injector. At φ = 0.65, the flame was quite unstable for both swirl injectors. With the medium swirl injector, the flame would oscillate between two different flame structures, one that was more or less attached to the vortex funnel, and one that was lifted well above the vortex funnel. The MS case at φ = 0.65 was at the very edge of the lean flammability limit, and would on occasion extinguish.
Observations of Flame Behavior in a Laboratory-Scale Pre-Mixed Natural Gas/Air Gas Turbine Combustor From LDA Velocity Measurements
Authors: Hedman Paul O. , Murray Robert L. , Fletcher Thomas H.
Published: February 2009

The objective of this study was to obtain simultaneous axial/radial and axial/tangential velocity measurements in a laboratory-scale, gas-turbine combustor (LSGTC) with a pre-mixed, swirl-stabilized, natural gas flame. Velocity measurements were obtained at each of four operating conditions (high swirl and medium swirl at fuel equivalence ratios of 0.80 and 0.65). Example results of mean and standard deviation axial, radial, and tangential velocities are included in this paper for the high swirl (HS), φ = 0.80 case (most stable flame) and the medium swirl (MS), φ = 0.65 case (least stable case). Additionally, example probably density distributions (PDF) for the axial velocity at the 80 mm axial location are presented for the same two cases.
TINTELL: An Innovative Method for Blade Life Management
Authors: Hunik R. , Rooth R. A.
Published: February 2009

The determination of degradation of first row gas turbine blades during e.g. hot gas path inspections is very important: Misjudgement can cause severe damage in the gas turbine or lead to an unwanted reduction of the operational life of the blades. A novel method, called Tintell (a Dutch acronym for in-situ degradation determination during hot gas path inspections), to improve this determination is developed. The method is designed to be applicable without demounting the casing of the turbine. Only small openings are required for installing measuring equipment. The procedure for applying Tintell consists of three main phases: • selection of blades and critical area on blades, in order to reduce the amount of time required for measurements; • measurements of degradation; • determination of remnant life and prognosis of future degradation. Selection can be realised by temperature measurements (e.g. pyrometry) on the blades during operation, by acceptance tests and/or by strain measurements on all blades. A new optical strain measuring technique is under development for this, applying boroscope holes near the first row of blades and using the cooling holes on the blades as optical markers. The determination of remnant life is realised by comparing the results of the measurements with calculations produced by applying a sophisticated three-dimensional finite element model of the blades (based on ANSYS). With this model a prognosis of the degradation during a next operational period can be calculated. This quantitative information will help the operator of the gas turbine with the decision, whether or not to replace or refurbish blades.
Stressed Oxidation Life for a Carbon Fiber Reinforced Silicon Carbide Matrix Composite
Authors: Calomino Anthony , Verrilli Michael , Thomas David J.
Published: February 2009

Stress-rupture life and residual strength results obtained for a carbon fiber reinforced silicon carbide matrix composite are presented. The material used in this study had a chemical vapor infiltration silicon carbide matrix reinforced by T-300 carbon fibers in a two-dimensional woven cloth, with a plain weave architecture. Tests were conducted in a reduced oxygen environment of 1000 ppm O2/Ar at 1200 °C. The results from two sets of twenty creep rupture tests performed at a fixed stress are presented and discussed. In the first test set, specimens were run to failure. In the second set, rupture testing was interrupted after a fixed time interval and retained strengths were then measured. The results of this study reveal a simple deterministic relationship between the retained strength and residual life of the ceramic composite when exposed to the oxidative environment. Creep life was also observed to increase for specimens with wider tests section widths. Microstructural examination revealed damage mechanisms in the form of fiber oxidation and this points to the need for developing environmental models for predicting life of a component manufactured with this material.
Background Noise Effects on Combustor Stability
Authors: Lieuwen Tim , Banaszuk Andrzej
Published: February 2009

This paper considers the effects of background turbulent fluctuations upon a combustor’s stability boundaries. Inherent turbulent fluctuations act as both additive and parametric (also called multiplicative) excitation sources to acoustic waves in combustors. While additive noise sources exert primarily quantitative effects upon combustor oscillations, parametric noise sources can exert qualitative impacts upon its dynamics; particularly of interest here is their ability to destabilize a “nominally” stable system. The significance of these parametric noise sources increases with increased background noise levels and, thus, may play more of a role in realistic, high Reynolds number systems than experiments on simplified, lab scale combustors might suggest. The objective of this paper is to determine whether and/or when these effects might be significant. The analysis considers the effects of fluctuations in damping rate, frequency and combustion response. It is found that the effects of noisy damping and frequency upon the combustor’s stability limits is quite small, at least for the fluctuation intensities estimated here. The effects of a noisy combustion response, particularly of a fluctuating time delay between flow and heat release perturbations, can be quite significant, however, in some cases for turbulence intensities as low as <(u′/u¯)2>1/2∼5–10%. These results suggest that deterministic stability models calibrated on low turbulence intensity, lab scale combustors may not adequately describe the stability limits of realistic, highly turbulent combustors.
Experimental and Numerical Studies of the Velocity Field of a Triple Annular Swirler
Authors: Li Guoqiang , Gutmark Ephraim J.
Published: February 2009

Modern industrial gas-turbine spray combustors feature multiple swirlers and distributed fuel injection for rapid mixing and stabilization. The present paper is the first of a sequence of papers that aim to study the flow field of such combustors, the related combustion characteristics and their control. The present paper focuses on an experimental investigation of the velocity flow field downstream of a Triple Annular Swirler (TAS) and CFD description of the flow field inside the TAS. Multiple combinations of swirlers of various swirl level and rotational direction were tested in cold flow under atmospheric conditions without a confining combustion chamber. The experiments showed that a Central Toroidal Recirculation Zone (CTRZ) and an annular jet with internal and external shear layers characterize the flow field downstream of TAS. The CTRZ is axisymmetric but the jet contains imprints of the internal flow and has some nonaxisymmetric features. Numerical RANS results confirmed these observations and showed that the asymmetry relates to the effect of the internal swirling vanes on the jet flow.
Design Study of a Lean Premixed Prevaporized Counter Flow Combustor for a Micro Gas Turbine
Authors: Liedtke O. , Schulz A. , Wittig S.
Published: February 2009

The present paper describes a new burner for a micro gas turbine utilizing the lean premixed prevaporized (LPP) combustion. The major objective of the new combustor concept is to achieve low pollutant emissions, in particular carbon monoxide (CO) and nitrogen oxide (NOx). Therefore, a homogeneous air fuel mixture is imperative for a lean combustion. Due to the thermodynamic cycle conditions of the micro gas turbine, the combustion air temperature is too low for an intense evaporation of a liquid fuel droplet spray. The new combustor concept therefore, is based on fuel film evaporation on the hot inner surface of a premix tube. The heat required for fuel film evaporation is transferred from the hot combustion gases, flowing along the outer surface of the tube, through the tube wall. The combustor wall is a multi-layered assembly consisting of a ceramic inner liner, a compliant layer, and the outer metal casing. This design allows almost adiabatic combustion to be established. The design process of the combustor is assisted by comprehensive numerical studies of droplet and fuel film evaporation. The commercial CFD code “CFD-RC” has been utilized to investigate the isothermal flow of the combustor. The vortex flow of the burner, which provides for flame stabilization, is described in detail. First experimental tests have been conducted. Measured pollutant concentrations of the exhaust gases meet international standards and demonstrate the great potential of the new combustor.
Combustion Chamber for a Directly Wood Particle Fired Gas Turbine
Authors: Pelzmann Mario , Haselbacher Hermann
Published: February 2009

Most of the processes using wood fuels in gas turbine applications that are presently being studied are based on gasification of the wood fuel and operating the gas turbine with the product gas. An alternative is running the gas turbine with the hot gas from a wood combustor — the directly wood particle fired gas turbine. This technique offers the possibility to realise efficient and cost effective small scale power generation systems in the low power range (1–2 MWe). For realizing a directly wood particle fired gas turbine, the Institute of Thermal Turbomachines and Powerplants at the Vienna University of Technology developed a two stage combustor. Solid and liquid fuels require relatively long residence times and good mixing with the oxidant to be completely burned. This can be achieved in the primary stage designed as a cyclone combustor/gasifier. In the cyclone chamber, burning fuel particles are suspended, according to their size, caused by centrifugal and drag forces. This cyclone effect of the flow offers the possibility that big particles remain in the cyclone combustor until they have been completely burned. Using a two stage combustor, the combustion process can be divided into two zones: A primary zone for fuel-rich pyrolysed-gasified-combustion and a secondary zone where the gasification products from the primary zone are oxidized with excess air. Staged combustion has the potential to reduce NOx (NO, NO2 and N2O), CO and total hydrocarbons CnHm concentrations in the exhaust. A large series of test runs was carried out with 3 different fuels, numerous fuel feed rates and equivalence ratios in the cyclone combustor resulting in stable operating conditions and almost total carbon burn-out. The main purpose of the test runs was to investigate the effect of air staging and temperature on the emissions of CO, CnHm and NOx.
Impact of Ethane and Propane Variation in Natural Gas on the Performance of a Model Gas Turbine Combustor
Authors: Flores R. M. , McDonell V. G. , Samuelsen G. S.
Published: February 2009

In the area of stationary power generation, there exists a growing interest in understanding the role that gaseous fuel composition plays on the performance of natural gas-fired gas turbine systems. In this study, an atmospherically fired model gas turbine combustor with a fuel flexible fuel/air premixer is employed to investigate the impact of significant amounts of ethane and propane addition into a baseline natural gas fuel supply. The impacts of these various fuel compositions, in terms of the emissions of NOX and CO, and the coupled impact of the degree of fuel/air mixing, are captured explicitly for the present system by means of a statistically oriented testing methodology. These explicit expressions are also compared to emissions maps that encompass and expand beyond the statistically based test matrix to verify the validity of the employed statistical approach.
Advanced Catalytic Pilot for Low NOx Industrial Gas Turbines
Authors: Karim Hasan , Lyle Kent , Etemad Shahrokh , Smith Lance , Pfefferle William , Dutta Partha , Smith Kenneth
Published: February 2009

This paper describes the design and testing of a catalytically-stabilized pilot burner for current and advanced Dry Low NOx (DLN) gas turbine combustors. In this paper, application of the catalytic pilot technology to industrial engines is described using Solar Turbines’ Taurus 70 engine. The objective of the work described is to develop the catalytic pilot technology and document the emission benefits of catalytic pilot technology when compared to higher, NOx producing pilots. The catalytic pilot was designed to replace the existing pilot in the existing DLN injector without major modification to the injector. During high pressure testing, the catalytic pilot showed no incidence of flashback or autoignition while operating over wide range of combustion temperatures. The catalytic reactor lit off at a temperature of approximately 598K (325°C/617°F) and operated at simulated 100% and 50% load conditions without a preburner. At high pressure, the maximum catalyst surface temperature was similar to that observed during atmospheric pressure testing and considerably lower than the surface temperature expected in lean-burn catalytic devices. In single injector rig testing, the integrated assembly of the catalytic pilot and Taurus 70 injector demonstrated NOx and CO emission less than 5 ppm @ 15% O2 for 100% and 50% load conditions along with low acoustics. The results demonstrate that a catalytic pilot burner replacing a diffusion flame or partially-premixed pilot in an otherwise DLN combustor can enable operation at conditions with substantially reduced NOx emissions.