bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermo-Structural Analysis of a Micro Gas Turbine Jet- and Recirculation- Stabilized Combustion Chamber
Authors: Cirigliano Daniele , Grimm Felix , Kutne Peter , Aigner Manfred 
Published: January 2021

Abstract
Modern Micro Gas Turbines must be capable to operate at different load points, in order to fulfill the demand of Combined Heat and Power for which they are designed. The combustion chamber structures are therefore subjected to regularly variable thermal loads, yet remaining physically constrained at the rest of the structure. Hence, they experience variable metal temperatures, temperature gradients and thermal stresses which can lead to thermal failure. Typical failure mechanisms in combustion chambers are fatigue and creep. Oxidation can also play an important role.
In the present study, Computational Fluid Dynamics methods are used for validation of flow prediction, combustion and heat transfer of an atmospheric combustion chamber. Convective and radiative heat losses towards the ambient are specifically taken into account, leading to better agreement with experimental data from preceding studies. The comparison is presented in this paper. The real-scale machine-operated combustion chamber is then tested at its nominal high-pressure conditions. In this respect, the hereby validated numerical models are employed to simulate the high-pressure operation. A fully coupled Thermo-Structural analysis is performed in order to account for heat fluxes within the solid materials. By so doing, wall temperature distributions can be obtained.
The results from Fluid Dynamics simulations serve as input for a Finite Elements Analysis, which provides equivalent stress, strain and deformation distributions by using a linear elastic mechanical model. Such distributions highlight the most critical areas, allowing a first estimate of the components’ life according to thermo-mechanical fatigue. The additional influence of Creep and Oxidation is currently under development at DLR Stuttgart and will be presented in subsequent works.
Scalable Heat Transfer Characterization on Film Cooled Geometries Based on Discrete Green’s Functions
Authors: Saavedra Jorge , Athmanathan Venkat , Paniagua Guillermo , Meyer Terrence , Straub Doug , Black James , Ramesh Sridharan 
Published: January 2021

Abstract
The aerothermal characterization of film cooled geometries is traditionally performed at reduced temperature conditions, which then requires a debatable procedure to scale the convective heat transfer performance to engine conditions. This paper describes an alternative engine-scalable approach, based on Discrete Green’s Functions (DGF) to evaluate the convective heat flux along film cooled geometries. The DGF method relies on the determination of a sensitivity matrix that accounts for the convective heat transfer propagation across the different elements in the domain. To characterize a given test article, the surface is discretized in multiple elements that are independently exposed to perturbations in heat flux to retrieve the sensitivity of adjacent elements, exploiting the linearized superposition. The local heat transfer augmentation on each segment of the domain is normalized by the exposed thermal conditions and the given heat input. The resulting DGF matrix becomes independent from the thermal boundary conditions, and the heat flux measurements can be scaled to any conditions given that Reynolds number, Mach number, and temperature ratios are maintained.
The procedure is applied to two different geometries, a cantilever flat plate and a film cooled flat plate with a 30 degree 0.125” cylindrical injection orifice with length-to-diameter ratio of 6. First, a numerical procedure is applied based on conjugate 3D Unsteady Reynolds Averaged Navier Stokes simulations to assess the applicability and accuracy of this approach. Finally, experiments performed on a flat plate geometry are described to validate the method and its applicability. Wall-mounted thermocouples are used to monitor the surface temperature evolution, while a 10 kHz burst-mode laser is used to generate heat flux addition on each of the discretized elements of the DGF sensitivity matrix.
Design Method and Numerical Simulation Analysis of Special-Shaped Centrifugal Impeller: Part I — Design Method
Authors: Lei Jian , Qin GuoLiang 
Published: January 2021

Abstract
This paper presents the design method of the special-shaped centrifugal impeller based on the streamline curvature method. Some conclusions described in this article will be thoroughly analyzed and demonstrated in the second part. The second part mainly involves case analysis and numerical simulation of performance parameters. The design of a centrifugal impeller must yield blades that are aerodynamically efficient, easy to manufacture, mechanically sound, especially low noise during running. The blade shape is generated by specifying surface velocity distributions and consists of straight-line elements that connect points at hub and shroud. The new impeller changed the channel structure from the classic radial outflow to axial outflow and removed the U-shaped diffuser flow passage. At the same time, the anti-noise technology is applied to optimize the flow channel design. The theoretical comparison between the classic centrifugal impeller and the new impeller shows that, in the aspect of energy saving, the flow field distribution of the new impeller is more uniform, gas flow loss is significantly reduced and the compressor efficiency is obviously improved. In addition, due to the noise elimination characteristics of the distributed flow passage, the noise of the new impeller is obvious lower than the traditional centrifugal impeller. But due to the complexity of the flow channel form, the flow resistance of the flow channel will increase, however this resistance increase can be controlled by the flow channel design.
Novel Feature Based Approach for Turbomachinery Design and Analysis
Authors: Kannan Ashwin , Dubasi Krishna Kishor , Nasti Adele , Keskin Akin , Clough Joshua 
Published: January 2021

Abstract
Current turbomachinery design and analysis is a time consuming process, involving multiple teams and multi-disciplinary physics to be considered during the design stages. The geometry definition is a key enabler requiring better, clean and flexible designs at desired level of fidelity for all analyses. In order to achieve this, a fully parametric approach has been developed using a feature library (user defined features – UDFs) in a CAD package together with multiple tools to prepare the geometry for analysis.
The paper will describe the approach towards feature library creation for a whole aero engine application, the relevant steps to prepare the geometry for analysis, and the limitations. The feature library has been used to enable a new aero engine conceptual design from the whole engine aerodynamic gas path definition all the way to the structural design, providing the additional flexibility to perform trade-off studies through design of experiments (DOE). Results will be shown on variation of critical design parameters such as casing thicknesses, flange positions, and number of struts.
The selected example will clearly demonstrate the time-saving and better-quality product achieved compared to the traditional process, and the ability of the engineer to explore the design space better with inter-linked analysis tools through a master geometry definition.
Extensive Validation of HAWT Unsteady Modelling Using BEM and CFD
Authors: Peraro Raffaele , Menegozzo Luca , Dal Monte Andrea , Benini Ernesto 
Published: January 2021

Abstract
The present work aims to present two different approaches to model the unsteady aerodynamics of horizontal-axis wind turbines (HAWTs). A complete and extensive comparison has been established between the results obtained using a low-fidelity calculation tool, as the Blade Element Momentum (BEM), and a high-fidelity technique, as the Computational Fluid Dynamics (CFD). Regarding the first calculation strategy, an accurate revision in polar diagrams calculation and the implementation of yaw and dynamic stall routines have endowed the BEM code to predict the machine performance under unsteady flow conditions. In order to achieve an accurate validation, the proposed BEM solver has been tested on AOC 15/50 and NREL Phase VI wind turbines. Referring to CFD techniques, a three-dimensional unsteady model has been improved to study the aerodynamic behaviour of the machine in case of yawed incoming wind.
30 Years of Dry Low NOx Micromix Combustor Research for Hydrogen-Rich Fuels: An Overview of Past and Present Activities
Authors: Funke Harald H.-W. , Beckman Nils , Keinz Jan , Horikawa Atsushi 
Published: January 2021

Abstract
The paper presents an overview of the past and present of low-emission combustor research with hydrogen-rich fuels at Aachen University of Applied Sciences. In 1990, AcUAS started developing the Dry-Low-NOx Micromix combustion technology. Micromix reduces NOx emissions using jet-in-crossflow mixing of multiple miniaturized fuel jets and combustor air with an inherent safety against flashback. At first, pure hydrogen as fuel was investigated with lab-scale applications. Later, Micromix prototypes were developed for the use in an industrial gas turbine Honeywell/Garrett GTCP-36-300, proving low NOx characteristics during real gas turbine operation, accompanied by the successful definition of safety laws and control system modifications. Further, the Micromix was optimized for the use in annular and can combustors as well as for fuel-flexibility with hydrogen-methane-mixtures and hydrogen-rich syngas qualities by means of extensive experimental and numerical simulations. In 2020, the latest Micromix application will be demonstrated in a commercial 2 MW-class gas turbine can-combustor with full-scale engine operation. The paper discusses the advances in Micromix research over the last three decades.
Operation of SGT-600 (24 MW) DLE Gas Turbine With Over 60 % H2 in Natural Gas
Authors: Magnusson Rikard , Andersson Mats 
Published: January 2021

Abstract
Hydrogen is one of the leading options for storing energy from renewables and surplus electricity. Hydrogen is also a major constituent in various streams in the chemical industry and cannot always be used for better purposes than flaring or heat and power generation.
Siemens has identified the 24MWe SGT-600 3rd generation DLE gas turbine as a candidate for having a high hydrogen capability. The burners for using hydrogen in the SGT-600 have been developed for and by Additive Manufacturing technology. The advantages of this technology have been integrated into the presented design and therefore allowing:
• Rapid prototyping with possibilities for fast turnaround of tests and screening of various concepts
• Manufacturing of complex geometries with smart gas passages, very innovative cooling and mixing concepts
• Small series and minimum waste with reduced cost
• Good repeatability and stability of product quality
Burner development was carried out according to “the standard method within the industry”, meaning CFD-analysis, atmospheric single burner combustion testing followed by pressurized single burner combustion testing and finally a full-scale machine test at the SIEMENS Industrial Turbomachinery AB (SIT) test rig facility in Sweden. The rig is used for full scale testing of gas turbines in the power output range from 15MW to 62MW. It allows testing not only with standard natural gas but also gas mixtures with e.g. hydrogen or nitrogen can be run. The test facility has liquid fuel capability.
During the burner development process, a project including two SGT-600 running on up to 60 volume % hydrogen was awarded to Siemens. This meant that a very definite target for the development was set and the results of these efforts are presented in this paper.
An adapted 3rd gen. DLE burner design proved to be capable of using 100% hydrogen at SGT-600 full load conditions at the single burner high pressure tests giving only 35 ppm NOx@15%O2. This was a major step in the development of a hydrogen burner for the SGT-600.
The following full engine test with the same burner type showed the possibility to run with 60 vol-% H2 at 0–100% load while keeping stable combustion and achieving emissions below 25 ppm NOx@15%O2 in the standard operating range of the SGT-600. At lower loads higher hydrogen contents were tested (95 vol-%) but the flow capacity of the fuel system limited the full exploration of hydrogen capability of the SGT-600 3rd gen. DLE gas turbine.
The 3rd gen. DLE burner is also used in the 33MWe SGT-700 and the 62MWe SGT-800, which will also benefit from the development of the increased SGT-600 hydrogen capability. The results open the possibility of using H2 rich gas more widely in all gas turbine configurations using 3rd gen. DLE burner.
Lessons Learned From Freespans at Pipeline Watercourse Crossings
Authors: Ferris Gerry 
Published: January 2021

Abstract
Over the past 10 years inspections (site visits, boat based surveys or diver surveys) have been completed at nearly 20,000 pipeline watercourse crossings for 20 different pipeline owners. During the last 10 years there have been 721 unique locations where an exposed pipeline was found and at 213 of these locations a freespan was encountered. Only one of the freespans resulted in the failure (loss of product) of the pipeline. This record illustrates what is now become widely accepted, that pipeline exposure does not necessarily lead to pipeline failure. The record adds to this, pipeline freespan does not necessarily lead to failure. This highlights that the relevant question for “water loading caused pipeline failure” is: Does the combination of freespan length and water velocity exceed a combination that would lead to vortex induced vibration or the exceedance of the static load limit of the pipe?
Probabilistic Digital Twins for Transmission Pipelines
Authors: Ayello Francois , Liu Guanlan , Yang Yonghe , Cui Ning 
Published: January 2021

Abstract
Digitalization in the oil and gas industry has led to the formation of digital twins. Digital twins bring closer the physical and virtual world as data is transmitted seamlessly between real time sensors, databases and models. The strength of the digital twin concept is the interconnectivity of data and models. Any model can use any combination of inputs (e.g. operator owned data sets and sensors, third-party databases such as soil composition or weather data, results from other models such as flow assurance, threat modelling or risk modelling). Consequently, the result of one model may become the input of another. This strength is also a weakness, as uncertain (or missing data) will lead to a great source of uncertainty and may lead to wrong results. Worst case scenarios have been used to solve this issue without success. This paper presents a new concept: probabilistic digital twins for pipelines. Probabilistic digital twins do not lose uncertainty as results pass from one model to another, thus providing greater confidence in the final results. This publication reviews the probabilistic digital twin concept and demonstrates how it can be implemented using gas pipeline data from West Pipeline Company, CNPC.
Negligible Crack Growth Thresholds
Authors: Lamborn Lyndon , Nelson Greg , Harter James 
Published: January 2021

Abstract
This paper initiates use of fracture mechanics best practice growth models and tools for pipeline steels with full tri-region da/dN characterization. The utilities associated with establishing negligible crack growth thresholds are demonstrated.
Pipeline operators are often presented with decisions that could be supported with scientifically vetted and situationally accurate stress thresholds for negligible crack growth. The threshold stress-intensity factor, ΔKth, is the value for ΔK where the crack growth rate, da/dN, approaches the minimum threshold crack growth rate. Stress-intensity factors at or below this threshold value result in crack growth small enough for operators to practically ignore it in pipeline integrity assessments. Previously, a ΔKth value of 2.0 MPa*m0.5 had been suggested for general use in API 579[1]. The API 579 value appears conservative when compared to industry experience and established ΔKth for similar steel alloys across all stress ratios.
By establishing an on-shore pipeline specific ΔKth which considers a pipeline-specific da/dN threshold and stress ratio effects, operators are afforded the opportunity to:
• exclude certain pipelines or portions of pipelines from crack growth susceptibility,
• identify features with no life limit,
• adjust load / boundary conditions to preclude growth,
• improve computational efficiency by discarding load cycles below threshold, and,
• more accurately simulate crack growth scenarios
Pipeline crack growth testing has been researched to derive reasonable and prudent negligible ΔKth values through a closer examination of loading scenarios and environments which affect ΔKth. A da/dN threshold for when diminishingly small crack growth rates can be neglected for typical pipeline assets was determined based on observed pressure fluctuation frequencies. Applications and value derived from deployment of ΔKth are illustrated for North American pipeline assets. Environmental and blunting effects on ΔKth for near-neutral pH stress corrosion cracking previously developed are shown for comparison and utility.
Fully established negligible growth thresholds pave the way toward adoption of next-level fracture mechanics best practice models and tools such as AFGROW and NASGRO, and facilitates crack growth simulations and root-cause analysis.
Near Neutral pH Stress Corrosion Crack Growth Model Evaluation: PipeOnline™
Authors: Lamborn Lyndon , Nelson Greg , Stilwell Genevieve 
Published: January 2021

Abstract
The pipeline industry has long sought a unified near-neutral pH stress corrosion cracking (NNpHSCC) growth model, which fully describes salient growth elements. In response to this gap, the Pipeline Research Council International (PRCI) has funded a multi-year research project, partnering with the University of Alberta (Project SCC-2-12). With the project nearing completion, application of the proposed near-neutral pH stress corrosion cracking growth model to two operating pipelines with known populations of stress corrosion crack features is presented.
The remaining life of each crack feature detected by crack in-line inspection tools, under known loading, is calculated for two segments of operating pipelines in North America. The PRCI developed model, referred to as PipeOnline™, is compared to the legacy Enbridge linear growth and Paris Law models.
A calibration technique for correcting the length and depth of the ILI feature calls provided by the in-line inspection vendor is reviewed, which takes into account tool tolerance and corrects length and depth to more closely match field findings. Efficiency improvements gleaned from this calibration technique are illustrated. While this calibration methodology is unique to the pipeline operator, the method is reviewed to allow other operators to readily implement the technique if it is found to be warranted.
The PipeOnline model is tested for the post-calibration dimensions and compared to the legacy growth model. Each of the required inputs is defined, and methods of quantification are shown. Negligible growth thresholds are reviewed, and the truncation of stress cycles below the growth threshold is discussed. The strategy of deployment is shown, along with the proportion of features that are predicted to remain in dormancy.
Methods to account for mean stresses and load application frequency are presented. The resulting PipeOnline re-inspection interval is compared to that predicted by typical existing growth models and then contrasted with excavation results on the asset. Calibration of the governing equation coefficients with rationale for each term is proposed for the pipeline segments examined in the study, and recommendations made for potential implementation for other operators, along with follow-on research.
Slope Movement Inspection Using Axial Strain Data Across Multiple Lines and Repeat Inspections
Authors: ElSeify Mohamed , Cornu Sylvain , Karé Raymond , Fathi Ali , Richmond John 
Published: January 2021

Abstract
Axial strain inspection using the AXISS™ is an established tool in the pipeline operator’s toolbox to assess pipeline geotechnical threats and other strain related events. Consequently, there is a large database of axial strain data for several different pipelines operating in different environments and from multiple inspections at the same geographical locations.
The Cheecham slope, located south east of Fort McMurray, Alberta, is a known geohazard site crossed by six individual pipelines. The lines were constructed between 1999 and 2013 and have a size range of 10” to 36”. Five out of the six lines, 12” to 36”, have been inspected using the axial strain tool. The pipelines inspected cover a range of characteristics including, different vintages, pipe diameters and positions in the ROW. These differences, and the ILI runs provide an insight into the effect of a landslide event on the strain response of these pipelines.
Axial strain measurement of the multiple pipelines in the Cheecham slope’s ROW allows: i) a direct comparison between lines ii) evaluation of the strain profile across the slope iii) assessment of the magnitude of the axial strain in terms of pipe characteristics e.g. pipe vintage and mechanical properties. More importantly, the axial strain data may provide an additional tool to assess the effectiveness of strain mitigation steps carried out over the years.
An increase in the frequency of axial strain ILI runs resulted in additional data being available and more importantly data from run to run inspections spread over months or sometime years. A single run captures the strain at the time of inspection but run to run inspections provide an additional comparative tool to evaluate and monitor pipeline movement. Two out of the five lines inspected have run to run axial strain data. This paper takes the Cheecham slope as a case study to discuss the benefits of run comparison of ILI axial strain data either by comparing strain values of repeated runs for a single line or by the cross comparison of strain responses of different lines in the same ROW. The paper aims to demonstrate how run to run analysis of ILI axial strain data can be implemented as part of geohazard risk management program to asses strain risk profiles of these locations and to assess the effectiveness of strain mitigation programs previously undertaken by operators.