bluuebunny/crossref_metadata_2025 huggingface dataset:
Three distinct mutational mechanisms acting on a single gene underpin the origin of yellow flesh in peach
Authors: Falchi Rachele , Vendramin Elisa , Zanon Laura , Scalabrin Simone , Cipriani Guido , Verde Ignazio , Vizzotto Giannina , Morgante Michele
Published: July 2013

Peach flesh color (white or yellow) is among the most popular commercial criteria for peach classification, and has implications for consumer acceptance and fruit nutritional quality. Despite the increasing interest in improving cultivars of both flesh types, little is known about the genetic basis for the carotenoid content diversity in peach. Here we describe the association between genotypes at a locus encoding the carotenoid cleavage dioxygenase 4 (PpCCD4), localized in pseudomolecule 1 of the Prunus persica reference genome sequence, and the flesh color for 37 peach varieties, including two somatic revertants, and three ancestral relatives of peach, providing definitive evidence that this locus is responsible for flesh color phenotype. We show that yellow peach alleles have arisen from various ancestral haplotypes by at least three independent mutational events involving nucleotide substitutions, small insertions and transposable element insertions, and that these mutations, despite being located within the transcribed portion of the gene, also result in marked differences in transcript levels, presumably as a consequence of differential transcript stability involving nonsense‐mediated mRNA decay. The PpCCD4 gene provides a unique example of a gene for which humans, in their quest to diversify phenotypic appearance and qualitative characteristics of a fruit, have been able to select and exploit multiple mutations resulting from a variety of mechanisms.
Genome‐wide analysis of short interspersed nuclear elements SINES revealed high sequence conservation, gene association and retrotranspositional activity in wheat
Authors: Ben‐David Smadar , Yaakov Beery , Kashkush Khalil
Published: July 2013

Short interspersed nuclear elements (SINEs) are non‐autonomous non‐LTR retroelements that are present in most eukaryotic species. While SINEs have been intensively investigated in humans and other animal systems, they are poorly studied in plants, especially in wheat (Triticum aestivum). We used quantitative PCR of various wheat species to determine the copy number of a wheat SINE family, termed Au SINE, combined with computer‐assisted analyses of the publicly available 454 pyrosequencing database of T. aestivum. In addition, we utilized site‐specific PCR on 57 Au SINE insertions, transposon methylation display and transposon display on newly formed wheat polyploids to assess retrotranspositional activity, epigenetic status and genetic rearrangements in Au SINE, respectively. We retrieved 3706 different insertions of Au SINE from the 454 pyrosequencing database of T. aestivum, and found that most of the elements are inserted in A/T‐rich regions, while approximately 38% of the insertions are associated with transcribed regions, including known wheat genes. We observed typical retrotransposition of Au SINE in the second generation of a newly formed wheat allohexaploid, and massive hypermethylation in CCGG sites surrounding Au SINE in the third generation. Finally, we observed huge differences in the copy numbers in diploid Triticum and Aegilops species, and a significant increase in the copy numbers in natural wheat polyploids, but no significant increase in the copy number of Au SINE in the first four generations for two of three newly formed allopolyploid species used in this study. Our data indicate that SINEs may play a prominent role in the genomic evolution of wheat through stress‐induced activation.
Hypoperfusion and acute traumatic coagulopathy in severely traumatized canine patients
Authors: Abelson Amanda L. , O'Toole Therese E. , Johnston Andrea , Respess Meghan , de Laforcade Armelle M.
Published: July 2013

Objective

To determine the incidence of acute traumatic coagulopathy in dogs suffering severe trauma and to investigate the association of markers of hypoperfusion with coagulation abnormalities.

Design

A prospective observational study performed June, 2009 to February, 2011.

Setting

A university teaching hospital.

Animals

Thirty client‐owned dogs weighing >5 kilograms that were presented to the Tuft's Cummings School of Veterinary Medicine following severe trauma as defined by an animal trauma triage score (ATT) ≥5 and having received no resuscitation with IV fluids or blood products prior to blood sampling.

Interventions

None.

Measurements and Main Results

Prior to resuscitation, data obtained at the time of admission to the emergency service included HCT, platelet count, lactate concentration, pH, base excess, thromboelastrogram (TEG), prothrombin time, activated partial thromboplastin time, fibrinogen level, and protein C activity. Rectal temperature and ATT were recorded for all dogs. Neither HCT nor platelet count was significantly decreased in any of the dogs. Based on G values as measured by TEG, 10/30 dogs (33%) showed evidence of hypercoagulability. Hypocoagulability as determined by prothrombin time, activated partial thromboplastin time, or TEG was not shown in any of the 30 dogs.

Conclusion

Dogs with severe trauma may experience hypercoagulability that is unrelated to fluid resuscitation or transfusion therapy. Future studies are warranted to better characterize coagulation changes in dogs with severe trauma, particularly in relationship to fluid therapies and/or hemorrhage.
Comparison of invasive versus noninvasive blood pressure measurements before and after hemorrhage in anesthetized greyhounds using theSurgivetV9203
Authors: Drynan Eleanor A. , Raisis Anthea L.
Published: July 2013

Objective

To determine the agreement between blood pressure obtained with a noninvasive technique and direct technique using the Surgivet V9203 at varying blood pressure levels created using a canine hemorrhage model.

Design

Experimental study.

Setting

University Teaching Hospital.

Animals

Twenty‐nine greyhounds with an average weight of 30 kg. Approval from the Murdoch University Animal Ethics Committee was obtained (R228609).

Methods

Arterial blood pressure (BP) was measured noninvasively (NIBP) via a cuff placed over the dorsal metatarsal artery and via a catheter in the contralateral dorsal metatarsal artery (IBP). Retrospectively the blood pressure measurements recorded were divided into various BP categories. A total of 84 paired readings were obtained. The data were further analyzed with respect to heart rate [<120/min and >120/min]. Comparison of the measurements was performed using the Bland–Altman method.

Results

For all categories, BP measurements were generally lower when recorded using the oscillometric technique [Systolic (Sys) bias 4.20 kPa (31.54 mm Hg), mean bias 0.52 kPa (3.93 mm Hg), and diastolic bias 1.04 kPa (7.83 mm Hg)]. Mean arterial BP had the least bias and greatest precision in the hypotensive group (bias 0.174 kPa (1.3063 mm Hg), precision 0.79 kPa (5.89 mm Hg)), low BP group (bias 0.62 kPa (4.67mm Hg) and precision 0.89 kPa (6.67mm Hg)) and normotensive group [bias 0.76 kPa (5.71 mm Hg) and precision 1.16 kPa (8.73 mmHg)].

Conclusions

The results demonstrate that the agreement between NIBP measurements and IBP, are within the limits of agreement recommended by the American College of Veterinary Internal Medicine Hypertension Consensus Panel for all pressures except Sys BP. This suggests that mean and diastolic NIBP using the Surgivet V9203 are a clinically acceptable alternative of IBP in hypovolemic hypotensive dogs.
Fatigue Assessment of Aluminum Ship Details by Hotspot Stress Approach
Authors: Tveiten Bård Wathne , Berge Stig , Wang Xiaozhi
Published: July 2013

This paper presents a robust methodology for fatigue assessment of aluminum ship details using a hot-spot stress range approach. A series of fatigue tests of a typical aluminum ship detail was carried out to obtain a design S–N curve. The test detail was analyzed by the finite element method using several modeling techniques and element types. The results from both experimental tests and finite element analysis are discussed. Recommendations on the procedure of fatigue assessment of aluminum ships including S–N curve to be used are also presented.
Thermal Dispersion in Porous Media—A Review on the Experimental Studies for Packed Beds
Authors: Özgümüş Türküler , Mobedi Moghtada , Özkol Ünver , Nakayama Akira
Published: July 2013

Thermal dispersion is an important topic in the convective heat transfer in porous media. In order to determine the heat transfer in a packed bed, the effective thermal conductivity including both stagnant and dispersion thermal conductivities should be known. Several theoretical and experimental studies have been performed on the determination of the effective thermal conductivity. The aim of this study is to review the experimental studies done on the determination of the effective thermal conductivity of the packed beds. In this study, firstly brief information on the definition of the thermal dispersion is presented and then the reported experimental studies on the determination of the effective thermal conductivity are summarized and compared. The reported experimental methods are classified into three groups: (1) heat addition/removal at the lateral boundaries, (2) heat addition at the inlet/outlet boundary, (3) heat addition inside the bed. For each performed study, the experimental details, methods, obtained results, and suggested correlations for the determination of the effective thermal conductivity are presented. The similarities and differences between experimental methods and reported studies are shown by tables. Comparison of the correlations for the effective thermal conductivity is made by using figures and the results of the studies are discussed.
Application of Groebner Basis Methodology to Nonlinear Static Cable Analysis
Authors: Jane Liu Y. , Buchanan George R. , Peddieson John
Published: July 2013

The governing equations for large deflections of cables have a highly nonlinear and coupled nature, which precludes exact analytical solutions except in a few simplified cases. The present study demonstrates the utility of Groebner Basis methodology in facilitating the construction of approximate analytical and semianalytical Galerkin solutions in the geometrically nonlinear analysis of cable statics.
Automatically Transforming Object-Oriented Graph-Based Representations Into Boolean Satisfiability Problems for Computational Design Synthesis
Authors: Münzer Clemens , Helms Bergen , Shea Kristina
Published: July 2013

Ever since computers have been used to support human designers, a variety of representations have been used to encapsulate engineering knowledge. Computational design synthesis (CDS) approaches utilize this knowledge to generate design candidates for a specified task. However, new approaches are required to enable systematic solution space exploration. This paper presents an approach that combines a graph-based object-oriented knowledge representation with first-order logic and Boolean satisfiability. This combination is used as the foundation for a generic automated approach for requirement-driven computational design synthesis. Available design building blocks and a design task defined through a set of requirements are modeled in a graph-based environment and then automatically transferred into a Boolean satisfiability problem and solved, considering a given solution size. The Boolean solution is automatically transferred back to the graph-based domain. The method is validated through two case studies: synthesis of automotive powertrains and chemical process synthesis for ethyl alcohol production. The contribution of the paper is a new method that is able to determine if an engineering task is solvable for a given set of synthesis building blocks and enables systematic solution space exploration.
Improvements to Common Data Reduction and Calibration Methods for Seven Hole Probes
Authors: Crawford James , Birk A. M.
Published: July 2013

The influence of calibration data sorting procedures and the order of polynomial curve fit used to calibrate seven hole pressure probes in subsonic, incompressible flow are discussed. It is shown that the inclusion of fourth order polynomial terms is necessary to properly model the physical response of the probe. It is also shown that the uniformity of probe response error is be significantly affected by polynomial extrapolation near sector boundaries, and that the uniformity can be improved by using some calibration points in multiple sectors.
Developing Statistically Defensible Propulsion System Test and Evaluation Techniques
Authors: Kidman David , Stevens Craig , Moulder Christopher , Kitto William , Brownlow James , Remund Todd
Published: July 2013

Acquisition of military hardware typically proceeds from design, development, production, and finally to operational use and support. Prior to the full-rate production, both developmental and operational test and evaluation (DT&E, OT&E) must occur to ensure that the system meets military requirements. The United States Air Force (USAF) is continually looking for ways to improve its test and evaluation techniques. Since 1997, Air Combat Command (ACC) has been successfully using Design of Experiments (DOE) to construct and analyze operational test efforts. This paper highlights recent efforts to pursue statistically defensible test techniques to aid developmental test efforts.

Defensible testing is a statistical approach similar to DOE by emphasizing the need for better test planning by:

• insistence on understanding the system under test;

• requiring clear and achievable test objectives;

• ensuring system performance is measurable;

• requiring that instrumentation accuracy and uncertainty propagation are well understood;

• and requiring confidence, power, and performance thresholds.

This paper highlights the Air Force Flight Test Center’s (AFFTC) first steps to improve aircraft propulsion system test and evaluation (T&E) through the implementation of statistically defensible test techniques. Background on the AF acquisition process, the Air Force vision for defensible testing, and an aircraft propulsion T&E case study are presented.
A Robust Radial Traverse Temperature Probe for Application to a Gas Turbine HP/IP Stage
Authors: Wilson A. J. W. , Ireland P. T. , Stevenson R. , Thorpe S. J. , Martin D.
Published: July 2013

The requirements to reduce engine fuel burn costs and gaseous emissions combine to ensure that gas turbine engine manufacturers continually seek to increase the peak cycle temperatures of new engine designs. Consequently, high-pressure turbine components must be developed that can withstand increasing gas temperatures, resulting in the continuous introduction of new technologies that allow appropriate service life. Accurate gas path measurements are vital for early understanding of the performance of a new design, although the accurate measurement of fluid temperature in a turbine stage is becoming increasingly difficult. The use of active probe-assembly cooling is important to ensure a sufficiently robust measurement system. Cooling issues may also affect the measurement performance because the component to which the temperature instrumentation is attached is cooled (for example, a guide vane). The use of a radial traverse total temperature device in the turbine section of a large civil aero-engine has previously been reported and the results analysed and compared to expectation. One outcome of ongoing work has been a proposal for a new design of turbine traverse probe with improved total temperature measurement accuracy. The new design directly addresses those uncertainties caused by conduction of heat from the thermocouple junction and into the cooled probe support. Extensive conjugate CFD modelling followed by validation tests in a high temperature free-jet rig confirmed the success of the design in reducing the magnitude of the thermal conduction error. The probe is likely to be used in future tests to improve engine performance validation.
Experimental Study of Blockerless Cascade Thrust Reverser
Authors: Shi Jingwei , Wang Zhanxue , Liu Chunyang , Gong Hao
Published: July 2013

Modern Aero-engine increasingly requires higher propulsive efficiency, lower weight and less fuel consumption, which motivates researchers all over the world to explore novel technology to achieve these goals. Blockerless cascade thrust reverser is one of such innovative technology, using high pressure secondary flow injecting into fan bypass to fulfill reverse thrust instead of traditional blocker door.

The efficiency of thrust reverser is a critical index of the technology, which is a function of aerodynamic and geometric parameters, including fan pressure ratio, secondary injection pressure ratio, injection angle, and injection position. The present study aims to investigate the effects of these parameters on reverse performance through basic demonstration experiments. Firstly, a simple experimental model was designed, which would be conducted on cascade experimental facility. Then, experiments were performed at static conditions, with fixed fluidic injection slot, variable injection angles (30°, 45°, 60°, 90°) at positions of Xj = 38.77mm, 58.77mm, 78.77mm, 98.77mm, 118.77mm, with the scheduled fan pressure ratios (FPR from 1.3 to 1.7) and secondary to ambient pressure ratios (SPR from 2.0 to 6.0). The results indicate that there exits an optimum injection location and injection angle for maximum thrust efficiency, and performance of blockerless cascade thrust reverser varies with diverse fan pressure ratio and secondary injection pressure ratio.
Ethanol and Distillate Blends: A Thermodynamic Approach to Miscibility Issues: Part 3 — Generalization to Other Alcohols (Methanol, Isopropanol and 1-Butanol)
Authors: Privat Romain , Jaubert Jean-Noël , Molière Michel
Published: July 2013

In the framework of a multistep program devoted to the ternary gasoil/alcohol/water system, the authors investigated the miscibility of anhydrous and hydrated ethanol qualities with four classes of industrial gasoil having different compositions and densities. To that end, they considered a pseudo binary system made by the various hydrocarbon species on one hand and the alcohol/water sub-system on another hand. Using the UNIQUAC thermodynamic theory and the Group Contribution approach, the team computed the Minimum Miscibility Temperature (“MMT”) for a series of the gasoil/ethanol/water system having water concentrations in ethanol comprised between 0 and 10%. The TMM is the temperature above which the various components of the system form a sole phase. This work is summarized in two papers already published (Part 1: GT 2010-22126; Part 2: GT2011-45896).

In the continuity of this prior work and considering the potential interest of alternative alcohols as “gasoil extenders”, the team has generalized this approach to selected C1-C4 alcohols: methanol, isopropanol (or 2-propanol) and n-butanol (or 1-butanol). While methanol is an interesting “energy vector” of coal and biomass via the CTL and BTL processes, isopropanol is a widespread commodity produced by the classical petrochemistry and 1-butanol is a promising biofuel candidate of the second, “lingo-cellulosic” generation.

This third part of the project shows that the introduction of these alternative alcohols and their respective interactions with water lead to considerable changes in the liquid-liquid equilibria and important shifts of the MMTs, trends that were difficult to anticipate beforehand.
Co-Firing of Kerosene and Biodiesel With Natural Gas in a Low NOx Radial Swirl Combustor
Authors: Altaher Mohamed A. , Li Hu , Andrews Gordon E.
Published: July 2013

Co-firing of biodiesel with natural gas, using a low NOx gas turbine combustor was investigated and compared with the equivalent natural gas and kerosene co-firing. The work was carried out at atmospheric pressure with 600K air inlet temperature and used an 8 vane radial swirler. Well mixed natural gas combustion was achieved using radially inward gas fuel injection through the wall of the swirler outlet throat. The biofuel was injected centrally using an eight hole radial fuel injector. This central fuel injector location forms a good pilot flame for natural gas low NOx combustion and was the only fuel injection location that biodiesel combustion could be stabilised. This was because central fuel injection was into the hot recirculating gases on the centreline that is a feature of radial swirl lean low NOX combustion. The biodiesel results were compared with equivalent tests for kerosene as the central injection fuel. Co-firing was investigated with a low level of main natural gas combustion that was held constant and the equivalence ratio was increased using the central injection of biodiesel or kerosene. Operation on kerosene with no acoustic problem was demonstrated up to Ø = 0.95. Three natural gas initial equivalence ratios were investigated with co-firing of liquid fuels, Ø = 0.18, 0.22 and 0.34. A key benefit of operating with hotter premixed combustion with natural gas was that the overall Ø at which stable low CO and HC operation could be achieved with biodiesel was extended to leaner overall Ø. The NOx emissions in this co-firing mode were remarkably low for relatively rich overall mixtures, where conventional single fuel main injection on natural gas gave higher NOx emissions.
Evaluation of Combustion Performance of a Coal-Derived Synthetic Jet Fuel
Authors: Lin Yang , Lin Yuzhen , Zhang Chi , Xu Quanhong , Sung Chih-Jen , Liu Guozhu
Published: July 2013

For application to aircraft turbines, the present work experimentally examines the physical and combustion-related properties of an F-T synthetic jet fuel relative to the Chinese standard jet fuel, RP-3. This fuel, derived from coal feedstock, is characterized in terms of its physical properties such as density, flash point, freezing point, surface tension, viscosity, and heating value in accordance with Chinese National Standard Testing Methods. Subsequently, several important characteristics relevant to its use in aircraft turbine engines are investigated using a single cup model combustor rig, including atomization, ignition, blowout, and exhaust emissions experiments are carried out. Preliminary results suggest that the use of coal-derived synthetic jet fuel will not result in adverse effects on the performance of an aircraft turbine combustor relative to conventional aviation kerosene. These initial results support the conclusion that full-scale engine testing is warranted to further investigate the performance of F-T synthetic jet fuels in practical systems, and to determine its ability to act as a “drop-in” replacement for traditional aviation fuel.
Numerical Investigation of Counter-Rotating Open Rotor Noise Emission in Different Flight Conditions
Authors: Busch Eirene Rebecca , Keßler Manuel , Krämer Ewald
Published: July 2013

Noise emission of a 9×7 and 8×8 open rotor configuration in cruise and in take-off conditions is examined by 3D unsteady numerical simulations utilising the chimera method to represent rotor movement. The acoustic analysis has been carried out with a Ffowcs Williams-Hawkings code over one rotor revolution with a resolution of 360 time steps. To ensure covering of all sources while keeping numerical losses low different hull surfaces have been examined. The comparison of two configurations at different flight conditions shows two main noise generating effects: the single rotor emission and emission caused by interaction of the rotors. The single rotor emission can mostly be seen in the rotor plane whereas the interaction can be examined at an angle of 20 to 45 and 135 to 155 degrees to the rotating axis with approximately the same share of total noise in take-off conditions. In cruise conditions the single rotor emission prevails over the interaction. This can be explained by the transonic blade tip speeds during cruise. Due to the reduced tip speeds in take-off interaction noise contributes to the total noise with a higher share than in cruise conditions. The 8×8-configuration shows higher noise emissions by interaction since the rotor-rotor interactions occur simultaneously.
Industrial Gas Turbine Diagnostics Using Fuzzy Logic
Authors: Barbosa Rafael , Ferreira Sandro
Published: July 2013

In this work a fuzzy based fault diagnosis system for an industrial gas turbine engine is presented. The system compares measured parameters and those calculated by a computer model, which sets the new and clean reference of the equipment. A fuzzy system classifies and quantifies the faults, which includes part load operation and takes into consideration the compressor variable geometry, which implies in a modification of the deviation pattern between the reference and the model. A commercial software, the GSP (Gas turbine Simulation Program), has been used for the process simulation. The reference software used is called NGGT (Natural Gas and Gas Turbine). Both were calibrated using a real industrial gas turbine operation data. Two compressor faults were simulated using GSP, the resulting variables were compared with those generated by NGGT. The fuzzy sets of the entry variables and the inference rules implemented in the fuzzy systems are dedicated to each fault. Thus, it is possible to add new faults and correct existing fault patterns without disturbing the other faults implemented. The system was tested for the two implemented faults by generating faulty test cases to several geometries and levels of damage. The results showed the robustness of the system and that it is possible to clearly identify the faults, for the several cases tested.
Influence of Microjet Condition on Characteristics of Supersonic Jet Noise and Flow Field
Authors: Okada Ryuichi , Watanabe Toshinori , Uzawa Seiji , Himeno Takehiro , Oishi Tsutomu
Published: July 2013

Jet noise reduction is essential for environmentally-friendly civil transport. Since jet noise becomes very intense in the case of supersonic aircraft, noise reduction is crucial topic for the realization of next-generation supersonic transport.

In the present study, experimental investigations were performed to clarify the effect of microjet injection on supersonic jet noise and flow field. The experiments were focused on supersonic jet with Mach number up to 1.47, which was generated from a rectangular nozzle with high aspect ratio.

Far-field acoustic measurements were conducted for widely ranged microjet conditions to understand the influence of the condition on characteristics of supersonic jet noise and flow field. For understanding the unsteady behavior of the flow field and the relation with noise reduction, flow field visualization was performed with schlieren technique using a high-speed camera.
Impact of Fuel Flexibility Needs on a Selected GT Performance in IGCC Application
Authors: Majoumerd Mohammad Mansouri , Breuhaus Peter , Smrekar Jure , Assadi Mohsen , Basilicata Carmine , Mazzoni Stefano , Chennaoui Leila , Cerri Giovanni
Published: July 2013

As part of a European Union (EU) funded H2-IGCC project, a baseline IGCC power plant was established; this was presented at the ASME Turbo Expo 2011 (GT2011-45701). The current paper focuses on a detailed investigation of the impact of using various fuels considering different operating conditions on the gas turbine performance, and the identification of technical solutions for the realization of the targeted fuel flexibility.

Using a lumped model, based on real engine data, compressor and turbine maps of the targeted engine were generated and implemented into the detailed GT model made in the commercial heat and mass balance program, IPSEpro. The implementation was done in terms of look-up tables. The impact of fuel change on the gas turbine island has been investigated and reported in this paper. Calculation results show that for the given boundary conditions, the surge margin of the compressor was slightly reduced when natural gas was replaced by hydrogen-rich syngas. The use of cleaned syngas instead of hydrogen-rich syngas resulted in a considerable reduction of the surge margin and elevation of the turbine outlet temperature (TOT) at design point conditions, when keeping the turbine inlet temperature (TIT) and compressor inlet mass flow unchanged. To maintain the TOT and improve the surge margin, when operating the engine with cleaned syngas, a combination of adjustment of variable inlet guide vanes (VIGV) and reduced TIT was considered. A parameter study was carried out to provide better understanding of the current limitations of the engine and to identify possible modifications to improve fuel flexibility.
Numerical Simulation of Propulsion System Integration for Very High Bypass Ratio Engines
Authors: Sibilli Thierry , Savill Mark , Sethi Vishal , MacManus David , Rolt Andrew M.
Published: July 2013

Due to a trend towards Ultra High Bypass Ratio engines, confirmed in projects like NEWAC (New Aero Engine Core Concepts, an European Sixth Frame Work Programme) the corresponding engine/airframe interference is becoming a key aspect in aircraft design. Therefore detailed aerodynamic investigations are required to evaluate the real benefits of these new technologies. The work presented in this paper is to perform these investigations for two typical twin-engine/low-wing transports, using Computational Fluid Dynamics, in order to create a useful integration module for the in-house aircraft/engine performance software TERA2020 (Techno-economic Environmental and Risk Assessment for 2020). The paper presents results for two NEWAC engines: Intercooled Core Long Range (IC L/R) and the Active Core Short Range (AC S/R). The main results show that the engine horizontal positioning can influence mission fuel burn by up to 6.4% for AC S/R and 3.7% for IC L/R respectively.
Thrust Reverser for a Mixed Exhaust High Bypass Ratio Turbofan Engine and its Effect on Aircraft and Engine Performance
Authors: Mahmood Tashfeen , Jackson Anthony , Rizvi Syed H. , Pilidis Pericles , Savill Mark , Sethi Vishal
Published: July 2013

This paper discusses thrust reverser techniques for a mixed exhaust high bypass ratio turbofan engine and its effect on aircraft and engine performance. The turbofan engine chosen for this study was CUTS_TF (Cranfield University Three Spool Turbofan) which is similar to Rolls-Royce TRENT 772 engine and the information available for this engine in the public domain is used for the engine performance analysis along with the Gas Turbine Performance Software, GasTurb 10. The CUTEA (Cranfield University Twin Engine Aircraft) which is similar to the Airbus A330 is used along side with the engine model for the thrust reverser performance calculations. The aim of this research paper is to investigate the effects on mixed exhaust engine performance due to the pivoting door type thrust reverser deployment. The paper looks into the engine off-design performance characteristics and how the engine components get affected when the thrust reverser come into operation. This includes the changes into the operating point of fan, IP compressor, HP compressor, HP turbine, IP turbine, LP turbine and the engine exhaust nozzle. Also, the reverser deployment effect on aircraft, deceleration time and landing distances are discussed.
Application of Endoscopic OH*-Chemiluminescence Measurements at a Full-Scale High-Pressure Gas Turbine Combustion Test Rig
Authors: Witzel Benjamin , Heinze Johannes , Kock Boris F. , Stockhausen Guido , Streb Holger , van Kampen Jaap , Schulz Christof , Willert Chris , Fleing Christian
Published: July 2013

Single burner combustion tests play a key role in the Siemens gas turbine combustion system development process. The main scope of these tests is to assess the performance of combustor design variants in terms emissions or combustion stability at gas turbine relevant operation conditions. Both emissions and combustion stability strongly depend on the flame front and flame position. A pragmatic approach to investigate the flame is to detect the chemiluminescence signal of the combustion intermediate species OH*. Thus, the OH*-chemiluminescence signal was recorded at high-pressure combustion tests to get more insight in the complex interactions between combustor design, operation conditions and combustion performance.

To minimize the impact of the measurement system on the combustion behavior, the optical access to the test rig was realized by using a water-cooled probe with an UV-transparent endoscope. The probe was located in the test rig side-wall, downstream of the burner outlet, viewing towards the burner with a 90° angle relative to the endoscope orientation. The experimental setup was completed by a combination of bandpass filters and an ICCD camera.

During the experiments acoustic pressure oscillations inside the combustion chamber were recorded simultaneously to the chemiluminescence images to allow for phase-sorting of the recorded images during the image post-processing. The post-processed images then were correlated with the pressure oscillations to investigate the relationship of the heat release to the pressure oscillations.

The measurements were carried out during single burner gas turbine combustion tests at realistic gas turbine operation conditions at a scaled pressure of 9 bar.

This paper presents selected test results and discusses how they give new insight in the complex combustion processes at full-scale high-pressure gas turbine combustion tests.
Durability of Oxide/Oxide CMCs in Gas Turbine Combustors
Authors: van Roode Mark , Bhattacharya Arun K.
Published: July 2013

An integrated creep rupture strength degradation and water vapor degradation model for gas turbine oxide-based CMC (Ceramic Matrix Composite) combustor liners was expanded with heat transfer computations to establish maximum TRIT (Turbine Rotor Inlet Temperature) for gas turbines with 10:1 pressure ratio. Recession rates and average CMC operating temperatures were calculated for an existing baseline N720/A (N720/Al2O3) CMC combustor liner system, with and without protective Al2O3 FGI (Friable Graded Insulation) for 30,000-h liner service life.

The potential for increasing TRIT by YAG (Y3Al5O12) substitution for the fiber, matrix and FGI constituents of the CMC system was explored, because of the known superior creep and water vapor degradation resistance of YAG compared to Al2O3.

It was predicted that uncoated N720/A can be used as a combustor liner material up to a TRIT of ∼1200°C, offering no TRIT advantage over a conventional metal + TBC (Thermal Barrier Coating) combustor liner. A similar conclusion was previously reached for a SiC/SiC CMC liner with BSAS-type EBC (Barium Strontium Aluminum Silicate Environmental Barrier Coating). The existing N720/A + Al2O3 FGI combustor liner system can be used at a maximum TRIT of ∼1350°C, a TRIT increase over metal + TBC and uncoated N720/A of ∼150°C. Replacing the Al2O3 with YAG is predicted to increase the maximum allowable TRIT. Substitution of the fiber or matrix in N720/A increases TRIT by ∼100°C.

A YAG FGI improves the TRIT of the 720/A + Al2O3 FGI by ∼50°C, enabling a TRIT of ∼1400°C, similar to that predicted for SiC/SiC CMCs with protective rare earth monosilicate EBCs.
Performance and Techno-Economic Investigation of On-Wing Compressor Wash for a Short-Range Aero Engine
Authors: Giesecke Daniel , Igie Uyioghosa , Pilidis Pericles , Ramsden Kenneth , Lambart Paul
Published: July 2013

The lower atmosphere is known to be relatively more concentrated with airborne pollutant. Short-range aircrafts are particularly more affected due to the altitude they operate, making them more susceptible to compressor fouling degradation. This usually leads to the demand for more fuel that increases the emissions, to make up for the reduction in the thrust. Compressor fouling is therefore a concern for aircraft operators due to increasing fuel cost and emission-based landing fees which impact the direct operating costs of an aircraft.

Highlighting the performance and economic benefits of compressor washing are the key aims of this study. An economic model is developed and the benefit is calculated for different wash intervals, which are based on the usual aircraft checks. The clean and fouled engine performance is simulated, indicating the impact of compressor fouling degradation on the twin-spool engine model. To emphasise the benefit of compressor washing, the degraded engine is compared to its new condition after washing. It was observed that it is impossible to fully recover the performance of a fouled compressor by an on-wing compressor wash.

This study concludes that compressor washing has a significant improvement on engine performance, as well as cost benefit in monetary terms. The results also suggest that compressor washing can reduce the unwanted thrust loss and exhaust gas temperature increase due to fouling, by half. A gross recovery of almost £75,000 per year for a short-range engine is shown to be achievable with a marginal increase of the total washing cost.
Unified Diagnostic Filtering for Turbofan Engine Control Systems Based on Matrix Pencil Observers
Authors: Tan Daoliang , Liu Yue , He Ai , Liu Yun , Kong Xiangxing , Wang Xi
Published: July 2013

Motivated by decoupling the adverse effect of exogenous disturbances on dynamic state filtering, unknown input observers (UIO’s) have received considerable attention in the fault diagnosis domain over the past decades. The model used in the UIO theory, however, does not include any disturbance item in system outputs. This can impair the robustness of diagnostic performance in the face of output disturbances. In this context, a unified filter, intended for both fault detection and isolation (FDI), is presented through the application of matrix pencil decomposition. First of all, a general fault model for the disturbed engine is formulated, with output disturbances considered. Then, this engine model is transformed by means of decomposing a matrix pencil derived from model matrices in a block triangular form. Based on this decomposition, a reduced-order subsystem can be obtained which is not affected by external disturbances. Finally, a single conventional filter with regional pole assignment constraints is designed to detect and isolate faults of an engine control system. Simulation results on one turbofan engine show the advantages of this given method over the UIO and Kalman filter.
Use of Electrical Resistivity and Acoustic Emission to Assess Impact Damage States in Two SiC-Based CMCs
Authors: Morscher Gregory N. , Baker Christopher , Ramasamy Sivakumar , Choi Sung , Faucett Calvin
Published: July 2013

The need to assess damage is essential to accurately predict the degradation of the composite properties such as remaining strength and specimen/component life expectancy. Two methods were used to assess as to their usefulness for damage quantification (acoustic emission) and damage monitoring (electrical resistivity) on two different CMC composites which have undergone impact damage. In particular melt-infiltrated composites with fiber types, SA and ZMI, are examined which were impacted with high velocity projectiles (∼ Mach 1), and tested in tension after high velocity impact. Electrical resistivity was used as both an inspection technique (measured before and after impact testing) as well as a damage monitoring technique in parallel with acoustic emission during tensile testing. The effect of damage was evident from the change in measured electrical resistivity due to impact and during tensile testing. It was also evident from AE activity during tensile testing that crack propagation occurred at relatively low stresses for composites with significant impact damage.
Total Pressure Correction of a Sub-Miniature Five-Hole Probe in Areas of Pressure Gradients
Authors: Town J. , Akturk A. , Camcı C.
Published: July 2013

Five-hole probes, being a dependable and accurate aerodynamic tools, are excellent choices for measuring complex flow fields. However, total pressure gradients can induce measurement errors. The combined effect of the different flow conditions on the ports causes the measured total pressure to be prone to a greater error. This paper proposes a way to correct the total pressure measurement.

The correction is based on the difference between the measured total pressure data of a Kiel probe and a sub-miniature prism-type five-hole probe. By comparing them in a ducted fan related flow field, a line of best fit was constructed. The line of best fit is dependent on the slope of the line in a total pressure versus span and difference in total pressure between the probes at the same location.

A computer program, performs the comparison and creates the correction equation. The equation is subsequently applied to the five-hole probe total pressure measurement, and the other dependent values are adjusted. The validity of the correction is then tested by placing the Kiel probe and the five-hole probe in ducted fans with a variety of different tip clearances.
Comparative Evaluation of CO2-O2 and Air (N2-O2) Gasification of Agricultural Biomass Fuels
Authors: Chen W. , Thanapal S. S. , Annamalai K. , Ansley R. J.
Published: July 2013

Biomass gasification is being considered as one of the most promising technologies for converting biomass into gaseous fuel. Here we present the results of gasification, using an adiabatic fixed bed updraft gasifier with air and carbon dioxide as gasification medium, for redberry juniper (Juniperus pinchotii), one of the woody species that dominate uncultivated lands in the Southern Great Plains, U.S.A., that may have potential for bioenergy utilization. The effect of gasifying the woody fuels with carbon dioxide (oxy fuel gasification) was carried out to study for increased production of carbon monoxide through Boudouard reaction. The effect of three different moisture contents: 5–6%, 11–12%, and 23–24%, on the tar yield was investigated for juniper using air as the gasification medium since the amount of tar in the gas produced impacts the way the gas is utilized for different applications. It was observed that oxy fuel gasification of juniper resulted in increased production of carbon monoxide at higher peak temperatures and hence increased heating value of the resulting gas mixture (6264 kJ/ Nm3 with inerts CO2 and N2, 19750 kJ/Nm3 inert free). It was found that the tar yield was more than 100 g/Nm3 of the gas produced using air as gasification medium for juniper fuels with moisture content between 5–6% and 11–12%. Also, the tar yield increased with the increase of equivalence ratio (ER). At a fixed ER, tar increased with the increasing moisture content. However, when the fuel moisture content reached 23–24%, the tar yield reduced significantly due low gasification temperature which reduced the pyrolysis and other gas phase reaction rates within the gasifier.
Effects of Advanced Engine Technology on Open Rotor Cycle Selection and Performance
Authors: Perullo Christopher A. , Tai Jimmy C. M. , Mavris Dimitri N.
Published: July 2013

Recent increases in fuel prices and increased focus on aviation’s environmental impacts have reignited focus on the open rotor engine concept. This type of architecture was extensively investigated in previous decades but was not pursued through to commercialization due to relatively high noise levels and a sudden, sharp decrease in fuel prices. More recent increases in fuel prices and increased government pressure from taxing carbon-dioxide production mean the open rotor is once again being investigated as a viable concept. Advances in aero-acoustic design tools have allowed industry and academia to re-investigate the open rotor with an increased emphasis on noise reduction while retaining the fuel burn benefits due to the increased propulsive efficiency. Recent research with conceptual level multidisciplinary considerations of the open rotor has been performed [1], but there remains a need for a holistic approach that includes the coupled effects of the engine and airframe on fuel burn, emissions, and noise.

Years of research at Georgia Institute of Technology have led to the development of the Environmental Design Space (EDS) [2]. EDS serves to capture interdependencies at the conceptual design level of fuel burn, emissions, and noise for conventional and advanced engine and airframe architectures. Recently, leveraging NASA Environmentally Responsible Aviation (ERA) modeling efforts, EDS has been updated to include an open rotor model to capture, in an integrated fashion, the effects of an open rotor on conventional airframe designs. Due to the object oriented nature of EDS, the focus has been on designing modular elements that can be updated as research progresses. A power management scheme has also been developed with the future capability to trade between fuel efficiency and noise using the variable pitch propeller system. Since the original GE open rotor test was performed using a military core, there is interest in seeing the effect of modern core-engine technology on the integrated open rotor performance. This research applies the modular EDS open rotor model in an engine cycle study to investigate the sensitivity of thermal efficiency improvements on open rotor performance, including the effects on weight and vehicle performance. The results are that advances in the core cycle are necessary to enable future bypass ratio growth and the trades between core operating temperatures and size become more significant as bypass ratio continues to increase. A general benefit of a 30% reduction in block fuel is seen on a 737–800 sized aircraft.
Establishing Operating Limits in a Commercial Lean Premixed Combustor Operating on Synthesis Gas Pertaining to Flashback and Blowout
Authors: Page David , Shaffer Brendan , McDonell Vincent
Published: July 2013

Operability issues such as flashback and lean blow out are phenomena that must be addressed for successful commercial operation of stationary gas turbines. The present work focuses on flashback and lean blow out of premixed jet flames in a combustor from a commercially available gas turbine operating on synthesis gas compositions. The issue of flashback is exacerbated when operating on fuels with high hydrogen content due to the increased reactivity of hydrogen, thus increasing the propensity for flashback. Operating margins for mixtures of natural gas and carbon monoxide in hydrogen are reported. The results interestingly demonstrate reduced stability for mixtures of H2/NG than for H2/CO. Increasing H2 percentage from 0% to 100% reduced blowout equivalence ratios from Φ = 0.63 to Φ = 0.29 for H2/NG and Φ = 0.42 to Φ = 0.29 for H2/CO. In addition, results obtained for inlet temperatures of 300K and 623K are compared and show an upward shift of the stability limits for higher preheats. Modeling of the experimental data using a perfectly stirred reactor predicts the effect of the addition of H2 to natural gas on the blowout limits. With regards to flashback some key factors that dominate the characteristics are identified and attempts to correlate data are carried out. The results show that lean blowout and flashback occur at the same AFT, regardless of preheat temperatures. AFT at flashback and lean blowout are compared to a more fundamental burner [1] with results indicating reasonable scalability.