bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cutaneous iridophoroma in a Green iguana ‬‬‬‬‬‬‬‬‬‬‬‬‬(Iguana iguana)‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬‬
Authors: Rousselet Estelle , De Mello Souza Carlos H. , Wellehan James F.X. , Epperson Ember D. , Dark Michael J. , Wamsley Heather L. 
Published: August 2017

AbstractAn 11‐year‐old intact male Green iguana (Iguana iguana) was referred for treatment of a probable iridophoroma based on previous cytopathology. A periocular mass was present near the right medial canthus. Computed tomography did not show any sign of metastasis. Clinicopathologic abnormalities included lymphopenia and hyperproteinemia. Cytologic and histologic evaluations of the mass were consistent with iridophoroma. Complete surgical excision of the mass was not possible without removal of the orbit due to local tissue involvement. Recovery and suture removal were unremarkable. Adjunctive radiation therapy was recommended, but not performed. A year later, the surgical site had healed well. To our knowledge, this is the first reported chromatophoroma cytopathology in a Green iguana. Chromatophoromas should be included in the differential diagnoses of pigmented skin tumors in reptiles. Early surgical excision is useful to limit local tissue destruction and metastatic potential.
Research on Active Control Strategy of Gas Turbine Secondary Air System in Different Ambient Temperature Conditions
Authors: Ji Jingjin , Huang Danping , Sun Bo , Peng Shuhong , Pan Chengxiong 
Published: August 2017

Conventional gas turbine secondary air system in early stage typically uses a fixed throttle unit between supply side which is compressor bleeding point and demand side which is turbine blade. The cooling air mass flow strongly depends on the extraction pressure characteristics of compressor. Optimal amount of cooling air is supplied only in design point in this way. The cooling air mass flow would be either too much or too less in off design condition.
Recently, heavy duty gas turbine manufacturers introduced an active control method for secondary air system. The main strategy is to adjust the cooling air valve set point as a function of gas turbine load percentage in order to adjust cooling air pressure ratio and cooling air mass flow as well. With this active control strategy, cooling mass flow is separated from compressor extraction pressure characteristics, and it can provide a better way to deal with combustion contaminant issues. But it is still a problem that there is no dependence relationship between cooling air valve set point and operating ambient temperature in that strategy. That is to say, the cooling air pressure ratio is constant while varying ambient temperature at base load.
In order to quantitatively analyze this phenomena, a 1-dimensional integrated gas turbine thermodynamic analysis method is first applied to obtain the extraction pressure characteristics of compressor for all bleeding points. In the meantime, the optimal cooling air mass flow for turbine blades in different operating conditions is evaluated by a 0-dimensional heat transfer assessment method. A 1-dimensional fluid network analysis method is then employed to calculate the cooling air mass flow variation characteristics for 2 typical throttle configurations between compressor bleeding points and turbine blades, the first one is setting a fixed throttle unit, and the second one is setting constant cooling air pressure ratio by a cooling air control valve. Quantitative calculation results show that the cooling air supply will not always meet the optimal requirements at different ambient temperature conditions with neither of the 2 configurations.
This paper further optimized the active control strategy. With the optimized strategy, cooling air supply not only no longer depends on extraction characteristics of compressor, but also could be actively adjusted according to the optimal requirements of turbine blades at different ambient temperature conditions. Performance evaluation results show that the optimized active control strategy could enhance the overall efficiency without exceeding maximum allowable metal temperature of turbine blades.
Analysis of the Effect of Multi-Row and Multi-Passage Aerodynamic Interaction on the Forced Response Variation in a Compressor Configuration: Part 1 — Aerodynamic Excitation
Authors: Schoenenborn Harald 
Published: August 2017

The aeroelastic prediction of blade forcing is still a very important topic in turbomachinery design. Usually, the wake from an upstream airfoil and the potential field from a downstream airfoil are considered as the main disturbances. In recent years, it became evident that in addition to those two mechanisms Tyler-Sofrin modes, also called scattered or spinning modes, may have a significant impact on blade forcing.
In Schrape et al. [9] it was found that in multi-row configurations not only the next, but also the next but one blade row is very important as it may create a large circumferential forcing variation which is fixed in the rotating frame of reference.
In the present paper a study of these effects is performed on the basis of a quasi 3D multi-row and multi-passage compressor configuration. For the analysis a harmonic balancing code, which was developed by DLR Cologne, is used for various setups and the results are compared to full-annulus unsteady calculations. It is shown that the effect of the circumferentially different blade excitation is mainly contributed by the Tyler-Sofrin modes and not to blade-to-blade variation in the steady flow field.
The influence of various clocking positions, coupling schemes and number of harmonics onto the forcing is investigated. It is also shown that along a speed-line in the compressor map the blade-to-blade forcing variation may change significantly.
In addition, multi-row flutter calculations are performed, showing the influence of the upstream and downstream blade row onto aerodynamic damping.
The effect of these forcing variations onto random mistuning effects is investigated in the second part of the paper.
Flow Interactions Between Shrouded Power Turbine and Nonaxisymmetric Exhaust Volute for Marine Gas Turbines
Authors: Gao Jie , Lin Feng , Niu Xiying , Zheng Qun , Yue Guoqiang , Fu Weiliang , Wei Ming 
Published: August 2017

The marine gas turbine exhaust volute is an important component that connects a power turbine and an exhaust system, and it is of great importance to the overall performance of the gas turbine. Gases exhausted from the power turbine are expanded and deflected 90 degrees in the exhaust volute, and then discharge radially into the exhaust system. The flows in the power turbine and the nonaxisymmetric exhaust volute are closely coupled and inherently unsteady. The flow interactions between the power turbine and the exhaust volute have a significant influence on the shrouded rotor blade aerodynamic forces. However, the interactions have not been taken into account properly in current power turbine design approaches.
The present study aims to investigate the flow interactions between the last stage of a shrouded power turbine and the nonaxisymmetric exhaust volute with struts. Special attention is given to the coupled aerodynamics and pressure response studies. This work was carried out using coupled computational fluid dynamics (CFD) simulations with the computational domain including a stator vane, 76 shrouded rotor blades, 9 struts and an exhaust volute. Three-dimensional (3D) unsteady and steady Reynolds-averaged Navier-Stokes (RANS) solutions in conjunction with a Spalart-Allmaras turbulence model are utilized to investigate the aerodynamic characteristics of shrouded rotors and an exhaust volute using a commercial CFD software ANSYS Fluent 14.0. The asymmetric flow fields are analyzed in detail; as are the unsteady pressures on the shrouded rotor blade. In addition, the unsteady total pressures at the volute outlet is also analyzed without consideration of the upstream turbine effects.
Results show that the flows in the nonaxisymmetric exhaust volute are inherently unsteady; for the studied turbine-exhaust configuration the nonaxisymmetric back-pressure induced by the downstream volute leads to the local flow varying for each shrouded blade and low frequency fluctuations in the blade force. Detailed results from this investigation are presented and discussed in this paper.
Model Based Prediction of Off-Design Operation Condition NOx Emission From DLE Gas Turbine Combustors
Authors: Lauer Martin , Färber Jens , Reiß Frank , El Masalme Jaman 
Published: August 2017

In this paper a semi-empirical method is presented to predict the NOX emission of a pilot stabilized, technically premixed gas turbine combustor for arbitrary combustor inlet conditions. The method is based on measurement data for a reference operation cycle and ISO ambient condition. A model based correction function is used to account for the change of NOX emission, which results from combustor inlet condition and/or operation cycle deviating from reference data.
The proposed method assumes that a pilot stabilized, technically premixed flame can be simplistically modeled as two separate combustion regimes: An assumed perfectly premixed regime, and an assumed diffusion flame regime. The emission of the combustor is then modeled as a superposition of the emissions from both individual combustion regimes. The emissions from the diffusion flame regime are the dominant contribution, although only a comparably small share of fuel is burnt in this regime.
The emission of the perfectly premixed combustion regime can be modeled as a sole function of flame temperature. On the other hand, the emissions from the diffusion regime are strongly affected by combustor inlet pressure and temperature, which are in turn a function of the gas turbine operation cycle and inlet conditions. To simplify matters, only the change in NOX emission from the diffusion regime, which results from deviation of combustor inlet pressure and/or temperature from values expected for a reference operation cycle and ISO ambient condition, is modeled. NOX emission data for this reference operation cycle is necessary experimental input for the method.
The proposed method can — with minimum experimental input — predict the NOX emission of a pilot stabilized, technically premixed combustor with good accuracy for arbitrary engine operation cycles and inlet conditions. It is aimed at providing reliable NOX emission estimates without the need for time intensive CFD or expensive experimental investigations. Typical applications are the assessment of a gas turbine’s NOX potential for feasibility studies of new operation or engine concepts with a proven combustor design, and for NOX estimates for out-of-experience ambient or site conditions for existing engines.
Verification of Single Digit Emission Performance of a 24 MW Gas Turbine: SGT-600 3rd Generation DLE
Authors: Manrique Carrera Arturo , Geipel Philipp , Larsson Anders , Magnusson Rikard 
Published: August 2017

The SGT-600 3rd generation DLE is a 24 MW industrial gas turbine which was recently upgraded from the SGT-600 2nd generation DLE. The upgraded SGT-600 is an addition to the existing low emissions gas turbine portfolio within Siemens. The objectives of the engine upgrade focused on increasing the lifetime of the components, lowering emissions and improving liquid fuel operation. In order to accomplish these objectives the combustion system was fully replaced, an improved gas fuel distribution was implemented and the first stage of the turbine was replaced. Furthermore, the liquid fuel injection system was enhanced in terms of fuel droplet distribution. Both gas and liquid fuel operation were confirmed in Siemens industrial gas turbine test facility located in Finspong, Sweden.
The upgraded combustion system originates from the SGT-700 gas turbine, a 33MW class engine, which consists of 18 “3rd generation DLE” burners that replaced the original “2nd generation DLE” ones that are normally incorporated in the SGT-600 DLE gas turbines. The first stage of the turbine has also been improved and less air is needed for cooling purposes. Moreover, an additional update on the compressor air bleed control was implemented. The liquid fuel burner hardware was optimized with new fuel injection lances manufactured by electron erosion techniques in order to improve the droplet distribution.
The SGT-600 3rd generation DLE is capable to operate in single digit conditions both in NOx and CO from 100% to 70% load and it is possible to extend single digit operation on NOx down to 50% load. CO emissions are below 80ppm at 50% load which is in compliance with current European regulation. Concerning liquid fuel operation the SGT-600 3rd generation DLE does not use water injection for emission control and is capable to reach below 58ppm NOx at full load while keeping CO below 40ppm down to 75% load.
The present work describes the main modifications performed during the engine upgrade and the results of the performed engine tests. Finally, it should be noted that the SGT-600 3rd generation DLE is an excellent example of the development/upgrade efforts within Siemens AG. The commercialization process of the SGT-600 3rd generation DLE has been initiated and three engines are already in commercial operation up to date, and two units will be installed in the near future.
High Temperature Brush Seal Development
Authors: Kirk Tracey , Bowsher Aaron , Crudgington Peter 
Published: August 2017

The industry bristle material of choice for brush seals has been the cobalt-based alloy Haynes®25 (also known as L605) for over 30 years. Haynes®25 has excellent oxidation resistance and wear properties in brush seal applications up to temperature of 620°C [1148°F]. Above this temperature creep resistance becomes undesirable for brush seal bristles and has lead to alternative sealing solutions to be implemented in these turbine locations. Nickel-based alloys have been explored as an alternative for Haynes®25 but have been shown to gall badly and wear quickly in comparison.
As increases in turbine performance have resulted in an increase in operating temperatures, it has lead to a need to find a bristle material that performs at temperatures above the limitation of Haynes®25. Initial experimental data has been obtained for a new cobalt-based alloy that shows potential for use as a bristle material at temperatures above 620°C [1148°F]. Further experimental results also indicate that the material appears to have better wear characteristics than Haynes®25 and may prove to be a feasible alternative in some cases.
This paper outlines a material selection process for brush seals, along with development of the alloy for use within brush seals and details of the comparative testing carried out at Cross Manufacturing Company.
ASME PTC-10 and Heat Capacity Relations for Polytropic and Isentropic Compression Process of Real Gas
Authors: Taher Matt 
Published: August 2017

ASME PTC-10 (reaffirmed 2009) serves as an internationally recognized standard factory acceptance and field performance testing for centrifugal compressors. It provides a test procedure to determine the thermodynamic performance of centrifugal compressors for gases conforming to ideal gas laws and for real gases. ASME PTC-10 defines ideal gases as those, which fall within the limits of table 3.3. The ratio of heat capacities is one of the parameters used to determine the limits of departure from ideal gas in table 3.3. However, ASME PTC-10 does not clearly define whether to use the ideal gas or a real gas method to calculate the ratio of heat capacities.
The relationship Ĉp – Ĉv = R, is valid for ideal gases, but not real gases. The validity of Ĉp – Ĉv = R is examined across a typical range of pressures and temperatures and a composition applicable to the natural gas industry.
Isentropic processes of ideal gases are accurately described with a simple relationship with the ratio of heat capacities. However, for real gases, that relationship is not valid and a more complex relationship is required for similar accuracy.
Thermodynamic relationships used in calculating isentropic and polytropic exponents are summarized. Limitations for real and ideal gas calculation methods are described. The deviations of real gas isentropic and polytropic volume and temperature exponents from ideal gas calculation methods are presented.
Development of Improvements to “Controlled Flow” Technology for Large Steam Turbines
Authors: Haller B. R. , Singh G. , Millington P. R. , Mund F. C. , Vernon K. 
Published: August 2017

The aim of this paper is to present advances in the blading design for large steam turbines — ‘Controlled Flow’ technology. The purpose of the design is to improve the turbine efficiency in a cost neutral manner, adding value for the customer. Controlled Flow is a 3D design philosophy which passes more flow through the efficient middle sections of the blade, and less flow through the comparatively inefficient regions near the endwalls. It has been used for the Impulse Technology Blading ITB guide blades. The current improvement builds on the previous successful Controlled Flow design but incorporates the following new features:
- Ultra High Lift for the mean section (at significantly reduced axial width)
- Ultra High Back Surface Deflection for the mean section
- forward leading edge sweep.
The new guide delivers the same radial distribution of absolute fluid exit angle to the runner as the previous design.
Confirmatory model turbine tests demonstrated that the new guide delivered a stage efficiency improvement of 0.35%, above an already very high datum level.
The endwall sections of the guide are kept the same which maintains the mechanical strength of the diaphragm (same stress and deflection). Therefore, the new design can easily ‘slot-in’ and replace the previous design.
The following will be described in detail:
- History of the designs/background and design philosophy
- Flow physics
- Stage optimization and performance prediction
- Probabilistic analysis and robustness of the design
- Confirmatory model turbine testing and validation (comparison with design predictions).
Aeroelastic Analysis of NREL Wind Turbine
Authors: Lu Yaozhi , Zhao Fanzhou , Salles Loic , Vahdati Mehdi 
Published: August 2017

The current development of wind turbines is moving toward larger and more flexible units, which can make them prone to fatigue damage induced by aeroelastic vibrations. The estimation of the total life of the composite components in a wind turbine requires the knowledge of both low and high cycle fatigue (LCF and HCF) data. The first aim of this study is to produce a validated numerical model, which can be used for aeroelastic analysis of wind turbines and is capable of estimating the LCF and HCF loads on the blade. The second aim of this work is to use the validated numerical model to assess the effects of extreme environmental conditions (such as high wind speeds) and rotor over-speed on low and high cycle fatigue.
Numerical modelling of this project is carried out using the Computational Fluid Dynamics (CFD) & aeroelasticity code AU3D, which is written at Imperial College and developed over many years with the support from Rolls-Royce. This code has been validated extensively for unsteady aerodynamic and aeroelastic analysis of high-speed flows in gas turbines, yet, has not been used for low-speed flows around wind turbine blades. Therefore, in the first place the capability of this code for predicting steady and unsteady flows over wind turbines is studied. The test case used for this purpose is the Phase VI wind turbine from the National Renewable Energy Laboratory (NREL), which has extensive steady, unsteady and mechanical measured data.
From the aerodynamic viewpoint of this study, AU3D results correlated well with the measured data for both steady and unsteady flow variables, which indicated that the code is capable of calculating the correct flow at low speeds for wind turbines.
The aeroelastic results showed that increase in crosswind and shaft speed would result in an increase of unsteady loading on the blade which could decrease the lifespan of a wind turbine due to HCF. Shaft overspeed leads to significant increase in steady loading which affects the LCF behaviour. Moreover, the introduction of crosswind could result in significant dynamic vibration due to forced response at resonance.
CFD Leakage Predictions of Unworn and Worn Labyrinth Seals With and Without Tooth Axial Offset
Authors: Chougule Hasham H. , Mirzamoghadam Alexander 
Published: August 2017

The objective of this study is to develop a Computational Fluid Dynamics (CFD) based methodology for analyzing and predicting leakage of worn or rub-intended labyrinth seals during operation. The simulations include intended tooth axial offset and numerical modeling of the flow field. The purpose is to predict total leakage through the seal when an axial tooth offset is provided after the intended/unintended rub.
Results indicate that as expected, the leakage for the in-line worn land case (i.e. tooth under rub) is higher compared to unworn. Furthermore, the intended rotor/teeth forward axial offset/shift with respect to the rubbed land reduces the seal leakage. The overall leakage of a rubbed seal with axial tooth offset is observed to be considerably reduced, and it can become even less than a small clearance seal designed not to rub. The reduced leakage during steady state is due to a targeted smaller running gap because of tooth offset under the intended/worn land groove shape, higher blockages, higher turbulence and flow deflection as compared to worn seal model without axial tooth offset.
An Implicit Off-Design Deviation Angle Correlation of Axial Flow Compressor Blade Elements
Authors: Dong-run Wu , Jin-fang Teng , Xiao-qing Qiang , Jin-zhang Feng 
Published: August 2017

This paper applies a new analytical/empirical method to formulate the off-design deviation angle correlation of axial flow compressor blade elements. An implicit function of deviation angle is used to map off-design deviation curves into linear correlations (minimum linear correlation coefficient R = 0.959 in this paper). Solution of the coefficients in the correlation is given through the study of classical theories and statistical analysis of the experimental data. The off-design deviation angle can be calculated numerically. The approach requires only knowledge of the blade element geometry. The comparison among 2 classical correlations and the new correlation proposed in this paper shows the new correlation has minimum error over the entire range of incidence angle while classical correlations show high reliability only in a limited range.
Experimental data in this paper is collected from NASA’s open technical reports. Rotors and stators are studied together. Considering there is significant deviation angle variation along spanwise direction, only data at 50% span is studied, if possible.
The error among experimental data, statistical regressions of the experimental data, and numerical results based on the new correlation is discussed. It has to be noted that the influence of the flow condition other than incidence angle is only being discussed but with less break through.