bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Novel SOFC Thermal Management Strategy of SOFC-GT Hybrid System With Anode and Cathode Control Loops
Authors: Chen Jinwei , Li Yuanfu , Zhang Huisheng , Lu Zhenhua 
Published: January 2021

Abstract
The SOFC performance and lifetime highly depend on the operation condition, especially the SOFC operation temperature. The temperature fluctuation causes thermal stress in electrodes and electrolyte ceramics. On the other hand, it also needs to maintain a sufficiently high temperature to enable the efficient transport of oxygen ions across the electrolyte. Therefore, it is necessary to design an effective SOFC temperature management system to guarantee safe and efficient operation. In this paper, a two-side temperature control method is proposed to avoid the temperature difference between anode and cathode. Therefore, the SOFC thermal management system includes two control loops. The anode inlet temperature and cathode inlet temperature are controlled by blowers adjusting the recirculated flow rate. In addition, the control performance of the proposed SOFC thermal management system is compared with one-side temperature control systems. The results show that both anode control loop and cathode control loop are essential to get a better control performance. The SOFC would operate with less efficiency with only anode temperature control. On the other hand, the safety problem would occur with only cathode temperature control. The temperature gradient would be more than the upper limit at a part load condition. Therefore, the SOFC thermal management strategy with anode and cathode temperature control loops is feasible for the SOFC-GT system.
Effect of Ribs on Heat Transfer and Pressure Drop in a U-Bend Channel With Double-Layer, Dome-Shaped Turning Vanes
Authors: Wu Bin , Yang Xing , Liu Zhao , Feng Zhenping 
Published: January 2021

Abstract
In this paper, the combined effects of ribs and double-layer, dome-shaped turning vanes on heat transfer and pressure drop are investigated in an idealized U-bend channel. Five kinds of ribs including transverse ribs, 45° ribs, 135° ribs, V-shaped ribs, and reverse V-shaped ribs combined with one kind of double-layer, dome-shaped turning vanes are applied. Baseline results are compared with the above composite cooling structures. Numerical simulations are performed by solving 3D, steady Reynolds-averaged Navier-Stokes (RANS) equations with k-ω turbulence model. The channel aspect ratio is 1:2 and its hydraulic diameter is 93.13 mm, respectively. Based on the cooling air inlet velocity and the channel inlet hydraulic diameter, the inlet Reynolds numbers are ranging from 100,000 to 440,000. The detailed three-dimensional fluid flow, pressure and heat transfer distributions are presented. Moreover, the thermal performances of the U-bend channel are also evaluated and compared with different cases.
The results revealed that combined with the double-layer, dome-shaped turning vanes, the transverse ribs case has the best thermal performance at the tip wall, and the reverse V-shaped ribs case is the best for the leading wall. The pressure drop of the channel with double-layer, dome-shaped turning vanes without any rib turbulator is the lowest, and that of the channel with inclined ribs is significantly higher than that of the channel with transverse ribs.
The superposition of the secondary flow induced by the ribs and the Dean vortex induced by the 180° sharp turn has a marked impact on the flow and heat transfer in the channel. In the double-layer, dome-shaped turning vanes channel, the mass flow distribution of the coolant also affects the heat transfer on the tip wall of the channel, and the ribs can adjust the mass flow distribution. The helical vortex superposed by the mainstream flow and the secondary flow induced by the ribs represents typical flow phenomenon in ribbed channels. The flow and development of the helical vortex are the main factors affecting the heat transfer on the leading/trailing walls.
Thermal History Coatings: Part I — Influence of Atmospheric Plasma Spray Parameters on Performance
Authors: Araguás-Rodríguez Silvia , Ferran-Marqués Marta , Pilgrim Christopher C. , Kamnis Spyros , Feist Jörg P. , Nicholls John R. 
Published: January 2021

Abstract
Firing temperatures in gas turbines have seen a steady increase over the years to allow for higher engine efficiencies and a decrease in hazardous emission levels. Conversely, these harsh conditions severely challenge the component lifetime, requiring a trade-off during the design process. Thus, it is crucial to understand temperature distribution across the majority of a component surface (&gt;80%) to verify the design and component durability. While a range of temperature measurement techniques are available, these are primarily focused on lower temperatures, exhibit low durability (thermal paints), require line of sight (pyrometers), are destructive (thermal crystals) and only provide point measurements (thermocouples, thermal crystals).
To overcome this challenge, Sensor Coating Systems (SCS) have developed Thermal History Coatings (THCs) to measure temperature profiles in the 900–1600°C range. This new temperature profiling capability records the past maximum exposure temperature in such a way that it can be determined once the component has already cooled down.
THCs are comprised of oxide ceramics deposited via Atmospheric Plasma Spraying (APS) to create a robust coating. APS deposition employs several variable parameters; spray settings such as gun power, gas flow or scan rate can affect the particle exposure and thus, the microstructure of the coating and its temperature sensing performance.
This two-part paper covers the THCs principles and demonstrates their capabilities for high-temperature applications. This first part shows, for the first time, the influence of APS parameters on luminescent measurements due to changes in the material microstructure. Extensive calibration data was used to develop a new model to relate the APS spray parameters to the luminescent properties in the as-deposited condition and consequent performance as a temperature sensor. The powder composition and the power and gas flow used during deposition were found to be the most influential parameters. The model identified the optimum spray parameters and was used to demonstrate THCs can achieve measurements in excess of 1600°C.
Analysis of Ignition Processes at Combustors for Aero Engines at High Altitude Conditions With and Without Effusion Cooling
Authors: Martinos Alexios-Dionysios , Zarzalis Nikolaos , Harth Stefan-Raphael 
Published: January 2021

Abstract
The ability to re-ignite at high altitude after a flameout event is critical for flight safety. One reason that makes the relight process of the engine difficult is the low temperature and pressure, which leads to poor atomization, low degree of evaporation and slow reaction rate of the vaporized fuel. For this research work a rectangular, one sector RQL combustion chamber was utilized for experimental investigations at high altitude conditions. The design of the chamber is modular so that experiments for two configurations, i.e. without and with effusion cooling holes can be conducted. The fuel injection and the ignition system are representative of the ones used in commercial aviation.
The investigations were performed in the frame of the European research project SOPRANO at the ISCAR rig. The ISCAR rig is capable of generating low pressure and temperature conditions for flowing kerosene-air mixtures.
The investigation focuses on the characterization of the ignition process, in terms of probability, minimum fuel to air ratio (FAR) and ignition timing for a successful ignition event. In addition, the unsteady flame kernel generation and propagation were analyzed by high-speed imaging recording.
An in-house image processing code was developed in order to derive quantitative spatial information of the flame and overall trends among ignition sequences for the same or different operating conditions.
In order to achieve comparability between the investigated configurations (liners without and with effusion cooling), the pressure drop across the nozzle and the liners was the same depending on the operating condition. Results show that both pressure and temperature affect the ignition process, with the former being the dominant parameter in the investigated conditions. In both configurations, the minimum FAR increased as long as the conditions in the chamber became more adverse, indicating that at high altitude low-pressure situations, the performance of the airblast atomizer deteriorated causing poor ignition. This is overcome by creating a richer fuel-air mixture in the primary zone. Finally, the air injected through the effusion cooling holes near the spark seems to create favorable conditions for the ignition process.
The Feasibility of an Euler-Lagrange Approach for the Modelling of Wet Steam
Authors: Wittmann Tim , Bode Christoph , Friedrichs Jens 
Published: January 2021

Abstract
This study investigates the applicability of an Euler-Lagrange approach for the calculation of nucleation and condensation of steam flows. Supersonic nozzles are used as generic validation cases, as their high expansion rates replicate the flow conditions in real turbines. Experimental and numerical validation data for these nozzles are provided by the International Wet Steam Modelling Project of Starzmann et al. (2018). In contrast to most participants of that project, an Euler-Lagrange approach is utilized for this study. Therefore, the classical nucleation theory with corrections and different droplet growth laws is incorporated into the Discrete Phase Model of ANSYS Fluent. Suggestions for an efficient implementation are presented. The Euler-Lagrange results show a good agreement with the experimental and numerical validation data. The sensitivities of the Euler-Lagrange approach to modelling parameters are analysed. Finally, an optimal parameter set for the calculation of nucleation and condensation is proposed.
Experimental and Numerical Researches in a Four-Stage Low Speed Research Compressor Facility
Authors: Zhu Mingmin , Qiang Xiaoqing , Ju Zhenzhou , Ma Yuchen , Teng Jinfang 
Published: January 2021

Abstract
The flow fields in rear stages of multi-stage axial compressor is difficult to measure in detail owing to the limited height and space. Thus, low speed research compressor (LSRC) facilities which are modelled from rear stages have been widely used to explore the internal flow fields and improve compressor design. A newly-designed vertical LSRC facility is established and put into used in Shanghai Jiao Tong University. The construction and design features of this LSRC facility are introduced in this paper. A cantilevered stage has been tested in this test rig. Compressor performance, inter-stage parameters distributions and contours are measured at design point and near stall point. Steady single passage simulations for four-stage compressor are carried out to validate numerical methods and further interpret the internal flow fields in test stages.
This vertical LSRC facility consists of inlet guide vane (IGV) and four repeated stages with an external diameter of 1.5 meter and a rotating speed of 900 RPM. The third stage is the mainly tested one, while the first and second stages provide the inlet conditions and the fourth stage provides the outlet conditions. Complete measuring methods and systems are established for this newly-built LRSC facility. The measurements of overall performance and inter-stage flow fields are carried out for test stage with cantilevered stator rows. The simulation for four-stage compressor are also performed for cantilevered configuration. The results of steady single-passage simulation have a similar trend with experimental ones, in terms of overall performance and parameters distributions.
Performance Characteristics of a Centrifugal Compressor With Capacity Control by Variable Diffuser Vanes
Authors: Im Kangsoo , Jeong Jongsik 
Published: January 2021

Abstract
A study of a variable diffuser vane capacity control method was done for the delivery of air into degasser of a SRU (Sulfur Recovery Unit) in a refinery process which requires a wide operating range and high head rise. Rig tests were made with diffuser vanes with various diffuser turning angles to evaluate performance of the compressor with variable diffuser vane. The compressor running on the test rig consisted of inlet bell mouth venturi, unshrouded impeller and vaned diffuser with tip clearance and scroll. To evaluate performance of the impeller and diffuser, static pressure was measured on the shroud side through 30 pressure tabs. The performance characteristics of the compressor stage, such as head coefficient, work coefficient, impeller exit flow condition and diffuser pressure recovery, are evaluated for 3 diffuser vanes and speeds. All performance characteristics are expressed as dimensionless form for each diffuser turning angle and speed. For the stage performance, compressor capacity is reduced as diffuser turning angle increase. For the impeller and diffuser performance, impeller exit flow coefficient is used for impeller exit flow condition and its performance. Based on the rig test, 6 customized single stage compressors with the variable diffuser vane capacity control system for the degasser of SRU were made and shop test were performed on each compressor. It was found that surge of the compressors can be controlled by variable diffuser vane and largely depends on the diffuser geometry.
Effect of Initial Surface Roughness on Water Erosion Resistance of Last Stage Blade Substrate of Steam Turbine
Authors: Li Fang , Wang Shunsen , Di Juan , Feng Zhenping 
Published: January 2021

Abstract
In order to study the effect of initial surface roughness on water droplet erosion resistance of last stage blade substrate of steam turbine, eight 17-4PH samples were grounded and velvet polished by different mesh metallographic sandpaper to establish sample with different initial surface roughness. The water droplet erosion experiments were carried out in the highspeed jet water erosion experiment system, and the mass and micro-morphology of each sample were measured by using precision electronic balance and ultra-depth of field microscope respectively at each experimental stage, and the measurement of water erosion trace width and maximum water erosion depth were also completed at the same time. On the basis of experiments, LS-DYNA was used for numerical simulation to verify the reliability of experimental results again. Results show that the smoother the initial surface of sample, then the smaller the mass loss, the stronger its water erosion resistance. On the contrary, the rougher the initial surface of sample, the more severe the surface irregularity, the more times the water droplets concentrated at the lowest point of pit when water droplets flow laterally after impact is completed, thus accelerating the formation of initial crack and lateral expansion, the poorer the water erosion resistance of sample. At same water erosion time, the smoother the sample surface, the later the complete erosion trace appear, the narrower the water erosion trace width. However, the maximum water erosion depth of sample is not affected by the initial surface roughness. The numerical simulation results are in good agreement with the experimental results.
Influence of Equation-of-States on Supercritical CO2 Combustion
Authors: Manikantachari K. R. V. (Raghu) , Martin Scott M. , Rahman Ramees K. , Velez Carlos , Vasu Subith S. 
Published: January 2021

Abstract
Fossil fuel based direct-fired supercritical CO2 (sCO2) cycles are gaining the attention of industry, academia and government due to their remarkable efficiency and carbon capture at high-source temperatures. Modeling plays an important role in the development of sCO2 combustors because experiments are very expensive at the designed operating conditions of these direct-fired cycles. Inaccurate density estimates are detrimental to the simulation output. Hence, this work focuses on comprehensive evaluation of the influence and applicability various equation-of-states (EOS) which are being used in the supercritical combustion modeling literature. A state-of-the-art supercritical combustion modeling methodology is used to simulate counter-flow supercritical CO2 flames by using various equation-of-states. The results show that, using the corresponding state principle to evaluate compressibility factor is not accurate. Also, van der Waal type EOSs predictions can be as accurate as complex Benedict-Webb-Rubin EOSs; hence van der Waal EOSs are more suitable to simulate sCO2 combustor simulations. Non-ideal effects are significant under the operating conditions considered in this work. The choice of EOS significantly influences the flame structure and heat release rate. Also, assuming the binary interaction parameter as zero is reasonable in sCO2 combustion simulations.
Applying Advanced Ultrasonic In-Line Inspection Technologies to Effectively Manage Hook Cracks
Authors: Wargacki Cory , Forshner Wade , Guajardo Rogelio , Hennig Thomas 
Published: January 2021

Abstract
Axial cracking inspections have become common place on a global level within pipeline operator’s integrity management programs. As technology continues to improve, operators are presented with more accurate assessments of the assets that are in current operation. However as more information is collected more threats are being identified and need to be assessed in a manner that is more applicable to their specific morphology. It is well known that vintage ERW manufacturing techniques can suffer from a wide range of potential threats such as lack of fusion or inclusions within the steel forming hook cracks during the rolling and welding process. Current In-line inspection technologies that are designed to detect, Identify and size cracklike flaws in pipelines are very proficient at doing so. However, due to the physical principals of the Ultrasonic pulse echo technology, deep features approaching, or above pulse echo saturation amplitudes pose challenges in determining accurate depth sizing.
In 2015 a Canadian pipeline operator determined the need to inspect one of their 16” assets for axial crack-like indications. During the analysis of this inspection data set, a number of saturated crack-like indications were reported. Saturated cracklike signals present a challenge to operators as they have to be considered in a conservative manner as 4mm or deeper which in turn leads to difficulties in the prioritization of resources associated with the excavation program.
The operator approached NDT Global in 2017, after the release of NDT Global’s Enhanced sizing depth algorithm to reevaluate the features that were present in the previous crack inspection data set. Working together with the operator, NDT Global applied the Enhanced sizing methodology to all features of significance in the pipeline segment and compared the results to lab measurements and in field NDE measurements.
The outcome of the reanalysis using the most up to date software algorithms utilizing enhanced sizing showed great benefits by increasing the accuracy of the crack depth sizing as NDT Global was now able to report full through wall depth sizing, however there were still some limitations on the ability to accurately size crack-like features as the primary threat is believed to be a result of hook cracks.
As a final step in this program NDT Global was provided sample spools that were cut out of the pipeline segment to perform a pull testing campaign utilizing the newest crack detection technology that was specifically targeted towards accurately sizing tilted and skewed crack like features.
The authors will briefly discuss the pipeline system and inspection campaign and in detail will discuss the benefits of using technology that has been developed to help pipeline operators better understand the threats in their integrity management program.
Pipe Stress and Deflection During an Integrity Dig
Authors: Naderi Ali , Deng Ruoqi , Yu Deli , Kania Richard , Li LePing 
Published: January 2021

Abstract
During a pipeline excavation, additional pipe stress and deflection can be produced due to altered soil support beneath the exposed pipe, which might bring in additional integrity concerns for the pipe under assessment. Classical beam theories and soil-spring modeling are inadequate for the complex pipe-soil interactions and boundary conditions. The objective of the present study was to develop a computational model that can be used to predict pipe stress and deflection during an integrity dig. The pipe-soil interaction was modeled with 3D elements using surface-to-surface contact approximation in ABAQUS. The pipe was assumed to be initially buried, then exposed for 12, 20, 30 and 34 m subsequently to mimic a buried pipeline under step-by-step excavation. The results indicated that the depth of soil support is a dominant factor for the pipe stress and deflection during an integrity excavation, which has not been previously investigated. Significant axial stress and strain in the longitudinal direction were produced by excavation, which may increase the risk of failure for the pipe that is suspected of circumferential defects. Furthermore, nonuniform soil support could cause substantial pipe deflections and stresses that may trigger an integrity dig. The model may be used to estimate the pipe stress and deflection prior to an integrity dig based on the soil conditions.
Full Encirclement Engineered Laminated Steel Sleeve System for Repairs and Augmentation of Pipelines: The Engineering Development, Validation Test Results, and Implications for Mitigation of Both Stress and Strain Dependent Integrity Threats
Authors: Laughlin Shawn , Leewis Keith , Alexander Chris 
Published: January 2021

Abstract
A full encirclement thin layer steel laminated sleeve system has been designed, developed, and optimized for pipeline integrity management applications. Development goals included the elimination of thixotropic concerns as well as the exclusion of the degradation of material properties of composite repairs. Elimination of cyclical fatigue of welded repairs and safety concerns associated with hot work were also considerations. The use of thin layer steel with a modulus matched to base pipe and steel’s homogenous isotropic properties enable axial calculations and evaluation of strain-based concerns. The thin layer steel laminated design results in extremely high fracture toughness and promotes intrinsic mitigation of potential future third party damage. The resulting system has demonstrated the reliable engineering data and analysis required for pipeline repairs and demonstrates applicability for the augmentation of existing pipes without defects.
An Engineering Critical Assessment (ECA) has been completed. This ECA follows the industry’s precedents of ASME B31G and ASME PCC-2 Article 4 type assessments and provides operators with greater functionality. This ECA has been named the Leewis Augmentation Analysis (LAA) and is presented, reviewed, and discussed.
Third party full scale ASME PCC-2 style burst testing has been completed. The results are presented. Highly instrumented tests were also conducted to determine an effective modulus of elasticity of the installed system as well as a determination of any delay in system acceptance of load. As installed, an effective modulus of 14 million psig (96526.60 MP)a with loading in layer 3 of the laminate at only 50 micro strain is reviewed. Long term creep and cyclical fatigue testing of the steel/adhesive laminate is presented and reviewed. 10 million cycles at 50% of ultimate lap shear has been achieved, which exceeds current industry practice by several orders of magnitude. The classic metal loss defect mitigation principle is reviewed and updated in light of these available technical advances. Finally, the implications for mitigation of both stress and strain dependent integrity concerns is discussed.