bluuebunny/crossref_metadata_2025 huggingface dataset:
Successful floral‐dipping transformation of post‐anthesis lisianthus (Eustoma grandiflorum) flowers
Authors: Fang Fang , Oliva Moran , Ehi‐Eromosele Sonia , Zaccai Michele , Arazi Tzahi , Oren‐Shamir Michal
Published: August 2018

The adaptation of the Agrobacterium‐mediated floral‐dipping technique is limited, to date, to a small number of plants. In this paper, we present the efficient transformation of one of the leading plants in the cut flower industry, lisianthus (Eustoma grandiflorum). This method is approximately 18 months shorter than the known tissue culture‐based transformation. The Excalibur Pink cultivar and two additional breeding lines, X‐1042 and X‐2541, were transformed using three different marker genes (benzyl alcohol acetyltransferase (BEAT) originating from Clarkia breweri, the feedback‐insensitive bacterial gene AroG*, and the empty pART27 vector expressing a kanamycin‐resistance cassette (nptII)). Genomic transformation was successful in all tested cases with transformation efficiency ranked from 0.2 to 2.9%, which is well in the range of results from Arabidopsis studies. Unlike Arabidopsis, in which floral‐dipping transformation was efficient only at a pre‐anthesis stage before ovary sealing, lisianthus flowers were transformed when dipping occurred 4 days pre‐anthesis or 3−5 days post‐anthesis with 1.5 and 3.7% efficiencies, respectively. Post‐anthesis transformation occurred when the flower ovaries were sealed. Flower dipping of Excalibur Pink flowers with fluorescent Agrobacterium containing a GFP marker gene demonstrated Agrobacterium entrance into the sealed flower ovary through the open stigma and style tube. In this study, we demonstrated floral‐dipping transformation of a commercial plant, lisianthus Excalibur Pink, occurring after sealing of the ovaries, probably via the stigma and wide open style tunnel.
The effect of broadband on European Union trade: A regional spatial approach
Authors: Barbero Javier , Rodriguez‐Crespo Ernesto
Published: August 2018

The positive effect of information and communication technologies (ICT) on trade between countries has been widely studied in the literature, but how ICT impacts regional trade is limited due to the lack of regional trade data. In this paper, we test whether broadband, as a proxy for ICT, increases bilateral trade at the regional level in Europe. We use a novel regional trade database of European Union regions and estimate an origin–destination flow gravity model for 2007 and 2010, accounting for spatial dependence among trade flows. Our results indicate that broadband is positive and significant in explaining trade patterns between European regions during both time periods.
Outcomes associated with transfusion in low‐risk women with obstetric haemorrhage
Authors: Patterson Jillian A. , Nippita Tanya A. , Randall Deborah , Irving David O. , Ford Jane B. ,   for the Obstetric Transfusion Steering Group
Published: August 2018

Background and Objectives

Obstetric haemorrhage is associated with increased blood transfusion, morbidity and health service usage in women. While the use of transfusion in actively bleeding patients is supported, there is little evidence for the use of blood as treatment in the nonbleeding patient following obstetric haemorrhage. Transfusion may expose women to increased morbidity. This study aims to compare outcomes between low‐risk women receiving no or 1–2 units of blood in the context of obstetric haemorrhage.

Materials and Methods

The study population included women giving birth in hospital in New South Wales, Australia, between July 2006 and December 2010, with a diagnosis of obstetric haemorrhage. Women with medical or obstetric conditions making them high risk were excluded, as were women receiving more than 2 units of blood. Data were obtained from linked hospital, birth and blood bank databases. Propensity score matching was used to compare outcomes between transfused and nontransfused women in order to estimate the impact of the transfusion itself on outcomes.

Results

There were 14989 women with obstetric haemorrhage, of whom, 1702 received a transfusion, including 1069 receiving a transfusion of 1–2 units. Women receiving transfusion were more likely to experience severe maternal morbidity (relative risk 7·0, 95% Confidence interval (2·8, 17·8)), be admitted to intensive care (RR 2·1 95% CI(1·2, 3·8)), and have a length of stay >5 days (RR 2·0, 95% CI (1·6, 2·5)).

Conclusions

Small volume transfusion in the context of obstetric haemorrhage among low‐risk women is associated with poorer maternal outcomes and increased healthcare utilisation.
Assessing the applicability of groundwater monitoring data in the modelling of soil water retention characteristics
Authors: Orzepowski Wojciech , Paruch Adam M. , Kowalczyk Tomasz , Pokładek Ryszard , Pulikowski Krzysztof
Published: August 2018

The present work focuses on an assessment of the applicability of groundwater table (GWT) measures in the modelling of soil water retention characteristics (SWRC) using artificial neural network (ANN) methods. Model development, testing, validation and verification were performed using data collected across two decades from soil profiles at full‐scale research objects located in Southwest Poland. A positive effect was observed between the initial GWT position data and the accuracy of soil water reserve estimation. On the other hand, no significant effects were observed following the implementation of GWT fluctuation data over the entire growing season. The ANN tests that used data of either soil water content or GWT position gave analogous results. This revealed that the easily obtained data (temperature, precipitation and GWT position) are the most accurate modelling parameters. These outcomes can be used to simplify modelling input data/parameters/variables in the practical implementation of the proposed SWRC modelling variants.
MODELING THE COSMOS: TRANSFORMATIVE PEDAGOGY IN SCIENCE AND RELIGION
Authors: Hickman Louise
Published: August 2018

This article reflects on the classroom pedagogy promoted by Christopher Southgate and its implications for the science–theology conversation. It highlights several important aspects of Southgate's pedagogy. The use of models of God, humanity, and cosmos emphasize relationality while encouraging the synthesizing of ideas. The promotion of holism in theological reflection is vital for nurturing students to become theologians themselves through the active reevaluation of key doctrines and ideas. An emphasis on ethical considerations reinforces synthesis between theology, science, and ethics, and is vital for perspective transformation. These aspects of Southgate's teaching should be recognized as vital for promoting intellectual independence, partnership, and theological transformation, all of which are essential to good science and theology pedagogy.
DARWIN AND CHRISTIANITY: TRUTH AND MYTH
Authors: Brooke John Hedley
Published: August 2018

In recent years many historical myths about the relations between science and religion have been corrected but not always with sensitivity to different types and functions of “myth.” Correcting caricatures of Darwin's religious views and of the religious reaction to his theory have featured prominently in this myth‐busting. With the appearance in 2017 of A. N. Wilson's depiction of Darwin himself as a “mythmaker,” it is appropriate to reconsider where the myths lie in discourse concerning Darwin and Christianity. Problems with Wilson's account are identified and his provocative demeaning of Darwin is contrasted with an image gleaned from Darwin's friend and colleague George Romanes. The article concludes with a brief reference to the problem of suffering and to the work of Christopher Southgate.
CHRISTOPHER SOUTHGATE'S COMPOUND THEODICY: PARALLEL SEARCHINGS
Authors: Edwards Denis
Published: August 2018

Christopher Southgate proposes that a theological response to the suffering that is built into an evolutionary world requires a compound evolutionary theodicy, made up of four interrelated theological positions. This article proposes a fourfold response to the suffering of nonhuman creation that parallels Southgate's compound theodicy. In its similarities and differences, it is offered in the spirit of a tribute to Christopher Southgate.
BETWEEN KNOWING AND BEING: REFLECTIONS ON BEING TAUGHT SCIENCE AND RELIGION BY PROFESSOR CHRISTOPHER SOUTHGATE
Authors: Gibson Timothy
Published: August 2018

It is a joy to be asked to contribute to this commemorative edition of Zygon, in honor of my friend Christopher Southgate. But a narrowly academic article seems not to fit the brief of writing a reflection on Southgate's teaching of science and religion, as one who has witnessed it, gladly, as both student and colleague. What follows, then, is deliberately reflective in tone, with little in the way of academic references apart from occasional links to Southgate's own work—though, I hope, enough of a strand of argument to justify inclusion in these pages. My argument is simply put: Southgate teaches by not teaching, but by drawing out knowledge from students and thereby empowering their growth. He is an exemplar, a kind man committed to the unfolding of understanding, interested too in forming dispositions in his students that will lead to their flourishing as thinkers and as people.
SOUTHGATE'S COMPOUND ONLY‐WAY EVOLUTIONARY THEODICY: DEEP APPRECIATION AND FURTHER DIRECTIONS
Authors: Russell Robert John
Published: August 2018

Christopher Southgate offers a remarkable evolutionary theodicy that includes six affirmations and arguments; together they form a unique and very persuasive proposal which he terms a “compound evolutionary theodicy.” Here I summarize the arguments and offer critical reflections on them for further development, with an emphasis on the ambiguity in the goodness of creation; the role of thermodynamics in evolutionary biology; the challenge of horrendous evil in nature; and the theological response to theodicy in terms of eschatology, with its own severe challenge from cosmology.
EXTINCTION, NATURAL EVIL, AND THE COSMIC CROSS
Authors: Peters Ted
Published: August 2018

Did the God of the Bible create a Darwinian world in which violence and suffering (disvalue) are the means by which the good (value) is realized? This is Christopher Southgate's insightful and dramatic formulation of the theodicy problem. In addressing this problem, the Exeter theologian rightly invokes the Theology of the Cross in its second manifestation, that is, we learn from the cross of Jesus Christ that God is present to nonhuman as well as human victims of predation and extinction. God co‐suffers with creatures in their despair, abandonment, physical suffering, and death. What I will add with more force than Southgate is this: the Easter resurrection is a prolepsis of the eschatological new creation, and it is God's new creation which retroactively determines past creation. Although this does not eliminate the theodicy question, it lessens its moral sting.
CREATIVE MUTUAL INTERACTION IN ACTION
Authors: Robinson Andrew
Published: August 2018

In this article, I describe a multidisciplinary project at the interface of philosophy, science, and theology. The project is the product of an ongoing collaboration between the author and Christopher Southgate, to whom this special issue of Zygon is dedicated. At the philosophical core of the project is a development of C. S. Peirce's semiotics (theory of signs). The scientific branch of the project involves the application of semiotic theory to the problem of the origin of life, and to questions about human evolution and human distinctiveness. The theological branch of the project involves the articulation of a semiotic approach to the Christian concepts of Incarnation and Trinity, and to the ideas of vestiges of the Trinity in creation and of participation in God's life. The purpose of this paper is to analyze the project in terms of Robert John Russell's model of ‘creative mutual interaction’ between science and theology.
THEODICY: A RESPONSE TO CHRISTOPHER SOUTHGATE
Authors: Hoggard Creegan Nicola
Published: August 2018

This article is a critical and appreciative interaction with Christopher Southgate's theodicy and theology of glory. I critique in particular his rejection of all dualist moves in theodicy. I question why Southgate can ascribe evil to some human actions, many of which are automatic and unconscious, but not to any other level or form of consciousness. I argue that he may rely too heavily on rational scientific categories, which are not sufficient in themselves to carry the weight of key theological concepts. His use of poetry is powerful and suggestive, but in the end, he may not give it enough epistemic weight.
Indian Implied Volatility Index: A Macroeconomic Study
Authors: Chittineni Jyothi
Published: August 2018

The study investigates the dynamic behavior of Indian implied volatility index and its time dependent conditional correlations with selected macroeconomic variables. The volatility of macroeconomic variables is likely to put burden on inflation and also influence the economic decisions as investment vehicles. Thus, the volatility of these variables has become central issue for fund managers and investors. The study uses three macroeconomic variables, oil price, gold price and federal fund rate over the period 2nd March 2009 to 30th June 2018. The Dynamic Regime-Switching model reveals that the Indian Implied volatility index exhibits two regimes high volatility and low volatility states. There exists a high degree of synchronicity between Indian VIX and oil price movement. Oil price has significant impact on India VIX during high volatile state. The result alarms the attention of monetary policy makers. The policy of oil price deregulation has to be carefully monitored.
Perceptions of Audience on Soundpainting Performance
Authors: Coskuner Sonat
Published: August 2018

Today, contemporary music emerges as an experimental phenomenon trapped in the laboratory environment rather than an element of skill. Modern music, where principles such as specialism and rationality are determinative, has become difficult to understand not only for performers who carry it on the stage but also for today's audience. One of the works done in recent years is Soundpainting, which is based on improvisation and allows everyone to do this stage art. Soundpainting is the multidisciplinary live composing sign language for Musicians, Dancers, Actors and Visual Artists. Presently the language comprises more than 1750 gestures that are signed by the Soundpainter to indicate the type of material desired of the performers. The Soundpainter (the composer) standing in front (usually) of the group communicates a series of signs using hand and body gestures indicating specific and/or aleatoric material to be performed by the group. The Soundpainter develops the responses of the performers, molding and shaping them into the composition. In this research, it is aimed to determine the perceptions of the audiences who are listeners in a Soundpainting performance and at the same time performers in Soundpainting performance. The specify of this perception is important in terms of determine the attitude of the listeners fort he first time involved in the Soundpainting performance as well as bringing solutions to the problem of music and alienation from a different point of view.
Gas Turbine Fouling Tests: Review, Critical Analysis, and Particle Impact Behavior Map
Authors: Suman Alessio , Casari Nicola , Fabbri Elettra , Pinelli Michele , di Mare Luca , Montomoli Francesco
Published: August 2018

Fouling affects gas turbine operation, and airborne or fuel contaminants, under certain conditions, become very likely to adhere to surfaces if impact takes place. Particle sticking implies the change in shape in terms of roughness of the impinged surface. The consequences of these deposits could be dramatic: these effects can shut an aircraft engine down or derate a land-based power unit. This occurrence may happen due to the reduction of the compressor flow rate and the turbine capacity, caused by a variation in the HPT nozzle throat area (geometric blockage due to the thickness of the deposited layer and the aerodynamic blockage due to the increased roughness, and in turn boundary layer). Several methods to quantify particle sticking have been proposed in literature so far, and the experimental data used for their validation vary in a wide range of materials and conditions. The experimental analyzes have been supported by (and have given inspiration to) increasingly realistic mathematical models. Experimental tests have been carried out on (i) a full scale gas turbine unit, (ii) wind tunnel testing or hot gas facilities using stationary cascades, able to reproduce the same conditions of gas turbine nozzle operation and finally, (iii) wind tunnel testing or hot gas facilities using a coupon as the target. In this review, the whole variety of experimental tests performed are gathered and classified according to composition, size, temperature, and particle impact velocity. Using particle viscosity and sticking prediction models, over seventy (70) tests are compared with each other and with the model previsions providing a useful starting point for a comprehensive critical analysis. Due to the variety of test conditions, the related results are difficult to be pieced together due to differences in particle material and properties. The historical data of particle deposition obtained over thirty (30) years are classified using particle kinetic energy and the ratio between particle temperature and its softening temperature. Qualitative thresholds for the distinction between particle deposition, surface erosion, and particle break-up, based on particle properties and impact conditions, are identified. The outcome of this paper can be used for further development of sticking models or as a starting point for new insight into the problem.
Influence of Scaling Parameters and Gas Properties on Overall Effectiveness on a Leading Edge Showerhead
Authors: Wiese Connor J. , Bryant Carol E. , Rutledge James L. , Polanka Marc D.
Published: August 2018

Testing new turbine cooling schemes at engine conditions becomes cost prohibitive as gas-path temperatures increase. As a result, turbine components are simulated in a laboratory with a large-scale model that is sized and constructed out of a selected material so that the Biot number is matched between the laboratory and engine conditions. Furthermore, the experimental temperatures are lower, so the surface temperature that the metal component would experience is scaled via the overall cooling effectiveness, ϕ. Properly measuring ϕ requires that the relevant flow physics must be matched, thus the Reynolds numbers is matched—both those of the freestream and the coolant, as well as the other scaling parameters, such as the mass flux, momentum flux, and velocity ratios. However, if the coolant-to-freestream density ratio does not match that of the engine condition, the mass flux, momentum flux, coolant and freestream Reynolds numbers, and coolant-to-freestream velocity ratios cannot be matched simultaneously to the engine condition. Furthermore, the coolant thermal transfer properties are unaccounted for in these parameters, despite their large influence on the resultant overall effectiveness. While much research has focused on the effects of the coolant-to-freestream density ratio, this study examines the influence of other thermodynamic properties, in particular the specific heat, which differ substantially between experimental and engine conditions. This study demonstrates the influence of various coolant properties on the overall effectiveness distribution on a leading edge by selectively matching M, I, and ACR with air, argon, and carbon dioxide coolants.
Development of a RANS Premixed Turbulent Combustion Model Based on the Algebraic Flame Surface Density Concept
Authors: Allauddin Usman , Pfitzner Michael
Published: August 2018

Recently, a fractal-based algebraic flame surface density (FSD) premixed combustion model has been derived and validated in the context of large eddy simulation (LES). The fractal parameters in the model, namely the cut-off scales and the fractal dimension were derived using theoretical models, experimental and direct numerical simulation (DNS) databases. The model showed good performance in predicting the premixed turbulent flame propagation for low to high Reynold numbers (Re) in ambient as well as elevated pressure conditions. Several LES combustion models have a direct counterpart in the Reynolds-averaged Navier–Stokes (RANS) context. In this work, a RANS version of the aforementioned LES subgrid scale FSD combustion model is developed. The performance of the RANS model is compared with that of the original LES model and validated with the experimental data. It is found that the RANS version of the model shows similarly good agreement with the experimental data.
The Effect of Coating Composition and Geometry on Thermal Barrier Coatings Lifetime
Authors: Pint Bruce A. , Lance Michael J. , Allen Haynes J.
Published: August 2018

Several factors are being investigated that affect the performance of thermal barrier coatings (TBC) for use in land-based gas turbines where coatings are mainly thermally sprayed. This study examined high velocity oxygen fuel (HVOF), air plasma-sprayed (APS), and vacuum plasma-sprayed (VPS) MCrAlYHfSi bond coatings with APS YSZ top coatings at 900–1100 °C. For superalloy 247 substrates and VPS coatings tested in 1 h cycles at 1100 °C, removing 0.6 wt %Si had no effect on average lifetime in 1 h cycles at 1100 °C, but adding 0.3%Ti had a negative effect. Rod specimens were coated with APS, HVOF, and HVOF with an outer APS layer bond coating and tested in 100 h cycles in air + 10%H2O at 1100 °C. With an HVOF bond coating, initial results indicate that 12.5 mm diameter rod specimens have much shorter 100 h cycle lifetimes than disk specimens. Much longer lifetimes were obtained when the bond coating had an inner HVOF layer and outer APS layer.
Cooperative Robot Exploration Strategy Using an Efficient Backtracking Method for Multiple Robots
Authors: Kim Jinho , Bonadies Stephanie , Eggleton Charles D. , Gadsden S. Andrew
Published: August 2018

This paper presents a cooperative robot exploration (CRE) strategy that is based on the sensor-based random tree (SRT) star method. The CRE strategy is utilized for a team of mobile robots equipped with range finding sensors. Existing backtracking techniques for frontier-based (FB) exploration involve moving back thorough the previous position where the robot has passed before. However, in some cases, the robot generates inefficient detours to move back to the position that contains frontier areas. In an effort to improve upon movement and energy efficiencies, this paper proposes the use of a hub node that has a frontier arc; thereby, the robots backtrack more directly to hub nodes by using the objective function. Furthermore, each robot cooperatively explores the workspace utilizing the data structure from the entire team of robots, which consists of configuration data and frontier data. Comparative simulations of the proposed algorithm and the existing SRT-star algorithm are implemented and described. The experiment is presented to demonstrate the application of the proposed strategy in real-time. Utilizing the proposed algorithm and exploration strategy, the results indicate that a team of robots can work more efficiently by reducing the distance of exploration and the number of node visited.
Control and Evaluation of a Motorized Attendant Wheelchair With Haptic Interface
Authors: Chuy Oscar Y. , Herrero Jonathan , Al-Selwadi Asma , Mooers Adam
Published: August 2018

Attendant wheelchairs provide a means to transport patients or mobility to people with walking disability. They can be attendant propelled, which are highly maneuverable in confined spaces, but offer no power assistance. Also, they can be electric powered with joystick control interface, which provides power assistance, but not as maneuverable as the attendant propelled wheelchair. With the objective of providing power assistance and having excellent maneuverability, this paper presents a motorized attendant wheelchair with haptic interface. Its control approach is based on virtual/desired dynamics, which is not the true dynamics of the wheelchair, but a mathematical model describing the motion behavior of a desired system. The desired dynamics takes the user's applied force/torque and yields desired velocities of the wheelchair. In the evaluation, tasks in confined spaces that require a lot of maneuvers were given and performed using the motorized wheelchair with haptic and joystick control interfaces. The results in terms of task completion times showed that motorized wheelchair with haptic significantly outperformed the motorized wheelchair with joystick interface. In addition, the performance of the motorized with haptic interface and attendant propelled wheelchairs were evaluated at two different loads. At heavy load, the task completion times of motorized wheelchair with haptic interface were comparable to the attendant propelled wheelchair.
Capability of the Bayesian Forecasting Method to Predict Field Time Series
Authors: Gatta Nicolò , Venturini Mauro , Manservigi Lucrezia , Ceschini Giuseppe Fabio , Bechini Giovanni
Published: August 2018

This paper addresses the challenge of forecasting the future values of gas turbine measureable quantities. The final aim is the simulation of “virtual sensors” capable of producing statistically coherent measurements aimed at replacing anomalous observations discarded from the time series.

Among the different available approaches, the Bayesian Forecasting Method (BFM) adopted in this paper uses the information held by a pool of observations as knowledge base to forecast the values at a future state.

The BFM algorithm is applied in this paper to Siemens field data to assess its prediction capability, by considering two different approaches, i.e. single-step prediction (SSP) and multi-step prediction (MSP). While SSP predicts the next observation by using true data as base of knowledge, MSP uses previously predicted data as base of knowledge to perform the prediction of future time steps.

The results show that BFM single-step average prediction error can be very low, when filtered field data are analyzed. On the contrary, the average prediction error achieved in case of BFM multi-step prediction is remarkably higher. To overcome this issue, the BFM single-step prediction scheme is also applied to clusters of time-wise averaged data. In this manner, an acceptable average prediction error can be achieved by considering clusters composed of 60 observations.
Dynamics of Coherent Structures and Random Turbulence in Pressure Side Film Cooling on a First Stage Turbine Vane
Authors: Ravelli S. , Barigozzi G.
Published: August 2018

This paper is based on a combined experimental and numerical investigation on pressure side film cooling in a high pressure turbine vane. The pressure side cooling geometry exhibits two staggered rows of cylindrical holes and a trailing edge cutback, fed by the same plenum chamber. The investigated conditions refer to low speed (exit isentropic Mach number of Ma2is = 0.2) and low turbulence intensity data. The choice of one only coolant-to-mainstream mass flow ratio equal to MFR = 1.5% was dictated by the hole discharge: on the one side, mainstream injection into the cooling holes and, on the other side, jet liftoff were avoided to get an effective thermal coverage downstream of the holes. Stress-Blended Eddy Simulation (SBES) model has been used to capture the unsteady physics of cooling jet-mainstream interaction downstream of each cooling row and cutback slot. The focus is on SBES capability of developing vortical structures at the interface between coolant and mainstream, as a function of local coolant-to-mainstream velocity ratio, because of their ultimate effect on vane surface temperature. Special attention has been paid to the shape and dynamics of coherent unsteadiness: SBES provided evidence of shear layer Kelvin-Helmholtz instability and hairpin vortices, downstream of cooling holes, with a Strouhal number (St) of 1.3 and 0.3–0.4, respectively. Simulated vortex shedding in the cutback region was characterized by St of 0.32, to be compared against the measured St value of 0.40.
Aerodynamic and Heat Transfer Experimental Investigation of Platform Cooling on a HP Nozzle Vane Cascade
Authors: Barigozzi G. , Mosconi S. , Perdichizzi A. , Abba L. , Vagnoli S.
Published: August 2018

The present paper reports on an experimental investigation carried out at Bergamo University Energy system and turbomachinery laboratory aiming to assess the aerodynamic and heat transfer performance of a high pressure nozzle vane cascade without and with platform cooling. Information collected from solid vane testing was used to design a first platform cooling scheme made of cylindrical holes. The cooling scheme was first aerodynamically tested to quantify its impact on secondary flows and related losses for variable injection condition. Heat transfer performances were then assessed through the measurement of the adiabatic film cooling effectiveness and of the convective heat transfer coefficient. From these data, the Net Heat Flux Reduction (NHFR) parameter was computed to critically assess the cooling scheme. The collected data set is significant for the design process, as it is useful for CFD validation and for the setting up of correlations. In particular, a MFR = 0.7% resulted to be the best injection condition for this geometry, being a compromise between aerodynamic loss augmentation, a good thermal protection inside of the passage and a limited heat load increase to the end wall.
Exergy Loss Considerations in Education for a Turbofan Power Cycle
Authors: Wettstein Hans E.
Published: August 2018

The conversion of heat into mechanical shaft power or electrical energy is still the worldwide most used electric and propulsion energy source. Whether coal, liquid hydrocarbons, natural gas, nuclear or solar heat are used as primary energy source such cycles are continuously improved aiming at better efficiency, at flexible operating conditions or at reducing manufacturing or maintenance cost.

The classic thermal power cycle design uses detailed simulation of the cycle fluid’s changes of state (typically represented by averaged pressure and temperature or specific enthalpy) along the flow paths. Components of such a cycle may be ducts, filters, mixers, compressors, combustors, heat exchangers, nozzles, turbine stages etc.

The notations of exergy and anergy were invented in the nineteen-fifties but they still play an astonishingly silent role in education. Knowing already the Carnot factor a student can understand the second law of thermodynamics by the simple fact that the exergy part of energy can be converted into any other form of energy while the anergy part cannot be converted into any exergy form of energy. The most used approach via the saying “that the state variable entropy can only grow” is for most students a mental detour because they do not understand the tie of energy conversion and entropy.

The exergy loss breakdown of a cycle gives an instructive view to opportunities and challenges. This paper explains methods to calculate a breakdown of the exergy losses with the example of a typical but notional turbofan using commercially confirmed component performance data.

The considerations cover exergy losses by heat exchange, by combustion, by heat loss to ambient, by mixing different fluids, by internal pressure losses, by friction and dissipation in turbomachinery and by the bottoming heat discharge as well as in the propulsive process. Quantified exergy losses for such effects make the limitations of technical improvements visible without going into detailed design work.

The purpose of this paper is to motivate for teaching and using exergy-based considerations especially in the basic performance simulation. Additionally the context is occasion for an extra plea on replacing the colloquial expression “energy consumption” by “exergy consumption”. The reader of this paper should have basic knowledge of thermodynamic cycle performance simulation methods and of turbomachinery.
Influence of Wet Steam on the Five-Stage Steam Turbine Efficiency
Authors: Hoznedl Michal , Kolovratník Michal , Tajč Ladislav , Weiß Andreas P. , Mrózek Lukáš
Published: August 2018

In the paper the behaviour of the five-stage experimental steam turbine 10 MW is described during the expansion transition from superheated steam to wet steam as well as the influence of wet steam on the flow path efficiency. The influence of wet steam occurrence on one to four last stages is given by setting the inlet steam parameters. The wetness of steam behind the last stage is calculated using two methods, first by enthalpy drop with the output measured by water brake and second by an optical probe. The results of both methods are compared. The impact of steam wetness increasing on a decrease in turbine efficiency is observed. In the paper the influence of steam wetness on the individual stage efficiency is also described and wetness loss coefficient is determined. Using the optical probe, assessment of poly-disperse structure of fine droplets is carried out, which is presented here by Sauter mean diameter. A pneumatic probe is used to define the distribution of velocities and pressures along the blade length after the last stage.
Rotordynamic Characterization of a Staggered Labyrinth Seal: Experimental Test Data and Comparison With Predictions
Authors: Cangioli Filippo , Vannini Giuseppe , Pennacchi Paolo , Ciuchicchi Lorenzo , Nettis Leonardo , Chatterton Steven
Published: August 2018

As well known, the stability assessment of turbomachines is strongly related to internal sealing components. For instance, labyrinth seals are widely used in compressors, steam and gas turbines and pumps to control the clearance leakage between rotating and stationary parts, owing to their simplicity, reliability and tolerance to large thermal and pressure variations. Labyrinth seals working principle consists in reducing the leakage by imposing tortuous passages to the fluid that are effective on dissipating the kinetic energy of the fluid from high-pressure regions to low-pressure regions. Conversely, labyrinth seals could lead to dynamics issues. Therefore, an accurate estimation of their dynamic behavior is very important.

In this paper, the experimental results of a long-staggered labyrinth seal will be presented. The results in terms of rotordynamic coefficients and leakage will be discussed as well as the critical assessment of the experimental measurements.

Eventually, the experimental data are compared to numerical results obtained with the new bulk-flow model (BFM) introduced in this paper.
Intentional Mistuning With Predominant Aerodynamic Effects
Authors: Martel Carlos , Sánchez José J.
Published: August 2018

Intentional mistuning is a well known procedure to decrease the uncontrolled vibration amplification effects of the inherent random mistuning and to reduce the sensitivity to it. The idea is to introduce an intentional mistuning pattern that is small but much larger that the existing random mistuning. The frequency of adjacent blades is moved apart by the intentional mistuning, reducing the effect of the blade-to-blade coupling and thus the effect of the random mistuning. The situation considered in this work is more complicated because the main source for the blade damping is the effect of the aerodynamic forces (as it happens in a blisk for a family of blade dominated modes with very similar frequencies). In this case the damping is clearly defined for the tuned traveling waves but not for each blade. The problem is analyzed using the Asymptotic Mistuning Model methodology. A reduced order model is derived that allows us to understand the action mechanism of the intentional mistuning, and gives a simple expression for the estimation of its beneficial effect. The results from the reduced model are compared with those from a finite element model of a more realistic rotor under different forcing conditions.
Developments of a Flow Visualization Borescope and a Two-Phase Flow Probe for Aeroengine Transmission Gears
Authors: Arisawa Hidenori , Shinoda Yuji , Noguchi Yoshiyuki , Goi Tatsuhiko , Banno Takahiko , Akahori Hirofumi
Published: August 2018

In order to reduce oil dynamic power loss in aeroengine gearboxes, visualizations and measurements of the oil-flow are effective. In the research presented in this paper, we developed a flow visualization borescope which can qualitatively visualize oil flow and a two-phase flow probe which can quantitatively measure oil/air ratio and the flow velocity. The flow visualization borescope consists of a 16mm diameter pipe in which an air purge passage for removing oil mist and a borescope are integrated with an illumination laser light and optical lenses, enabling clear high-speed photography. The two-phase probe consists of a 5mm diameter pipe with a 1mm diameter measurement hole and has a pressure adjustment pipe inside the pipe. For a demonstration, a shrouded spur gear with 100 m/s peripheral speed and 20 liters/min oil supply was used. Flow visualization at 30000 frame/sec imaging shows that oil outflow from the shroud opening spreads turbulently over the whole width of the opening. Oil/air ratio and flow velocity measurement by the two-phase flow probe show that there was thin oil-rich layer on the shroud wall and the flow speed was slow compared with the gear peripheral speed. The measurement equipment we developed was easily installed to the gearbox and therefore it is expected to apply to real aeroengine gearboxes.
Numerical Simulations of CO2 Compressors at Near-Critical and Sub-Critical Inlet Conditions
Authors: Hosangadi A. , Weathers T. , Liu Z. , Ahuja V. , Busby J.
Published: August 2018

An advanced real-fluid numerical framework for transcritical CO2 spanning both the supercritical and sub-critical regime near the critical point is presented. The numerical algorithm is specifically designed to faithfully model sharp variations of thermodynamic derivatives near the critical point. Numerical results for compressor performance in the Sandia test loop [1] at near critical inlet conditions have been presented over a range of flow rates from the choke point to the stall line. The analysis identifies the shift in the flow losses from the impeller to the diffuser as the flow rate increases from the stall to choke limit. The simulations have been compared with both the Sandia performance curves as well as raw data from Barber Nichols Inc. (BNI); the results compare well with the raw data and provide good qualitative comparisons with Sandia’s performance curves [1].

The numerical framework has also been extended to sub-critical conditions by solving for separate transport equations for each phase. Methodology for NIST table lookup at sub-critical conditions to identify liquid and vapor properties has been developed. Phase change is triggered when local conditions go sub-critical and do not require the phase to be specified a priori. Calculations at both near critical inlet temperatures as well as a two-phase inlet condition at lower temperatures were modeled. Significant difference in the phase change characteristics at these two conditions have been identified and discussed in the paper.
Large-Eddy Simulation of Buoyancy-Induced Flow in a Sealed Rotating Cavity
Authors: Pitz Diogo B. , Chew John W. , Marxen Olaf
Published: August 2018

Buoyancy-induced flows occur in the rotating cavities of gas turbine internal air systems, and are particularly challenging to model due to their inherent unsteadiness. While the global features of such flows are well documented, detailed analyses of the unsteady structure and turbulent quantities have not been reported. In this work we use a high-order numerical method to perform large-eddy simulation (LES) of buoyancy-induced flow in a sealed rotating cavity with either adiabatic or heated disks. New insight is given into long-standing questions regarding the flow characteristics and nature of the boundary layers. The analyses focus on showing time-averaged quantities, including temperature and velocity fluctuations, as well as on the effect of the centrifugal Rayleigh number on the flow structure. Using velocity and temperature data collected over several revolutions of the system, the shroud and disk boundary layers are analysed in detail. The instantaneous flow structure contains pairs of large, counter-rotating convection rolls, and it is shown that unsteady laminar Ekman boundary layers near the disks are driven by the interior flow structure. The shroud thermal boundary layer scales as approximately Ra−1/3, in agreement with observations for natural convection under gravity.
Assessment of Wall-Modeled LES for Pre-Swirl Cooling Systems
Authors: Kusbeci Mazhar E. , Chew John W.
Published: August 2018

Although conventional Reynolds-averaged Navier-Stokes (RANS) models of turbulence are generally used for predicting the performance of gas turbine pre-swirl systems, these models are known to have shortcomings. Motivated by the need to predict mixing where cooled-cooling air (CCA) and un-cooled cooling air (UCA) streams are introduced in pre-swirl systems, computational fluid dynamics (CFD) modelling capability is reassessed. An initial study focuses on a normal jet in crossflow (JICF), illustrating some of the shortcomings of a popular Reynolds-averaged Navier-Stokes (RANS) model and the possible advantages and disadvantages of wall-modeled large eddy simulation (WMLES). Pre-swirl system studies focus on a previously investigated low radius feed, direct flow configuration for which measurements and CFD solutions are available, and extend this to consider a mixed feed system. The velocities in the near-jet region of the pre-swirl chamber were predicted differently by unsteady RANS (URANS) and WMLES, however no significant differences were observed closer to the receiver holes. Comparing to measurements shows little overall difference between the models, with similar results to earlier studies. Although no measurements are available for a mixed feed system, comparison of predictions from the two models indicates significant sensitivity and uncertainty involved in these predictions.
Off-Design Prediction of Transonic Axial Compressors: Part 1 — Mean-Line Code and Tuning Factors
Authors: Kidikian John , Reggio Marcelo
Published: August 2018

With yearly advances in CFD techniques and methodologies, and the increased capacity and capabilities of computer CPU, GPU, and information storage, CFD has become a powerful design tool. However, despite its vast strengths, a CFD analysis is still based on the sound development of the 1D mean-line analysis methodology.

This paper (part 1 of 2) describes an off-design axial compressor mean-line code, tested in a specialized engineering software for the development and analysis of a whole gas turbine engine, and the various tuning factors used to obtain an off-design performance match. It will be shown that, to obtain a proper match of the off-design performance of single-stage transonic axial compressors, both the rotor and stage pressure ratio, and the rotor temperature ratio are required to be converged upon. To do so, the off-design mean-line analysis requires the incorporation of a set of inlet & exit blockage factors and deviation angles that vary with the compressor performance conditions. This approach differs from the literature-based procedural assumptions (or rule-of-thumb) of fixed inlet and exit blockage factors of approximately “0.98”, and the use of a unique deviation angle based on Carter’s rule.

The results obtained in this paper are then used to develop a generalized off-design mean-line loss modelling methodology (part 2 of 2) capable of predicting the off-design performance of four well documented NASA transonic axial compressors.
Aerodynamic Interaction Between Incoming Vortex and Tip Leakage Flow in a Turbine Cascade
Authors: Zhou Kai , Zhou Chao
Published: August 2018

In turbines, secondary vortices and tip leakage vortices develop and interact with each other. In order to understand the flow physics of vortices interaction, the effects of incoming vortex on the downstream tip leakage flow are investigated in terms of the aerodynamic performance in a turbine cascade. Experimental, numerical and analytical methods are used. In the experiment, a swirl generator was used upstream near the casing to generate the incoming vortex, which interacted with the tip leakage vortex in the turbine cascade. The swirl generator was located at ten different pitchwise locations to simulate the quasi-steady effects. In the numerical study, a Rankine-like vortex was defined at the inlet of the computational domain to simulate the incoming swirling vortex. Incoming vortices with opposite directions were investigated. The vorticity of the positive incoming swirling vortex has a large vector in the same direction as that of the tip leakage vortex. In the case of the positive incoming swirling vortex, the vortex mixes with the tip leakage vortex to form one vortex near the tip as it transports downstream. The vortices interaction reduces the vorticity of the flow near the tip, as well as the loss by making up for the streamwise momentum within the tip leakage vortex core. In contrast, the negative incoming swirling vortex has little effects on the tip leakage vortex and the loss. As the negative incoming swirling vortex transports downstream, it is separated from the tip leakage vortex and forms two vortices. A triple-vortices-interaction kinetic analytical model and one-dimensional mixing model are proposed to explain the mechanism of vortex interaction on the aerodynamic performance.
Compressive Sensing Approach for Aeroengine Fan Noise Mode Detection
Authors: Bu Huanxian , Yu Wenjun , Huang Xun
Published: August 2018

To further simplify the sensor array set-ups and improve the mode detection capability for the aeroengine fan noise test, a new compressive sensing based methodology has been proposed. This paper reports the details of the validated aeroengine fan noise test method and the wind tunnel test results for the validation. The experimental set-up consists of a transition duct to the open jet, a mode synthesizer to generate different modes of characteristic fan noise, and a sensor array to conduct mode detection in the presence of background flow speeds and background noise interference. The main attention is primarily focused on the examination of the associated reconstruction accuracy and probability of success for spinning mode detection. The testing results clearly show the potential capability of the proposed new testing method for aeroengine tests in a practical testing facility.
Thermoacoustic Limit Cycle Predictions of a Pressurised Longitudinal Industrial Gas Turbine Combustor
Authors: Xia Yu , Laera Davide , Morgans Aimee S. , Jones W. P. , Rogerson Jim W.
Published: August 2018

This article presents numerical prediction of a thermoacoustic limit cycle in an industrial gas turbine combustor. The case corresponds to an experimental high pressure test rig equipped with the full-scale Siemens SGT-100 combustor operated at two mean pressure levels of 3 bar and 6 bar. The Flame Transfer Function (FTF) characterising the global unsteady response of the flame to velocity perturbations is obtained for both operating pressures by means of incompressible Large Eddy Simulations (LES). A linear stability analysis is then performed by coupling the FTFs with a wave-based low order thermoacoustic network solver. All the thermoacoustic modes predicted at 3 bar pressure are stable; whereas one of the modes at 6 bar is found to be unstable at a frequency of 231 Hz, which agrees with the experiments. A weakly nonlinear stability analysis is carried out by combining the Flame Describing Function (FDF) predicted by LES with the low order thermoacoustic network solver. The frequency, mode shape and velocity amplitude corresponding to the predicted limit cycle at 209 Hz are used to compute the absolute pressure fluctuation amplitude in the combustor. The numerically reconstructed amplitude is found to be reasonably close to the measured dynamics.