bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adjoint-Based Aeroelastic Design Optimization Using a Harmonic Balance Method
Authors: Anand Nitish , Rubino Antonio , Colonna Piero , Pini Matteo 
Published: January 2021

Abstract
Turbomachinery blades characterized by highly-loaded, slender profiles and operating under unsteady flow may suffer from aeroelastic shortcomings, like forced response and flutter. One of the ways to mitigate these aeroelastic effects is to redesign the blade profiles, so as to increase aero-damping and decrease aero-forcing. Design optimization based on high-fidelity aeroelastic analysis methods is a formidable task due to the inherent computational cost. This work presents an adjoint-based aeroelastic shape-optimization framework based on reduced order methods for flow analysis and forced response computation. The flow analysis is carried out through a multi-frequency fully-turbulent harmonic balance method, while the forced response is computed by means of the energy method. The capability of the design framework is demonstrated by optimizing two candidate cascades, namely, i) a transonic compressor cascade and, ii) a supersonic impulse turbine rotor operating with toluene as working fluid, initially designed by means of the method of waves. The outcomes of the optimization show significant improvements in terms of forced-response in both cases as a consequence of aero-damping enhancement.
Effect of Suction Side Jet on the Shock Wave Boundary Layer Interaction in Transonic Turbine
Authors: Jian Liu , Wenhua Duan , Liangji Zhang , Weiyang Qiao 
Published: January 2021

Abstract
In this paper, the effect of round jet with inclination angle 135° upstream the throat on the suction surface on shock wave boundary-layer interaction was investigated in a transonic turbine cascade, and the vortical structures near the jet region were analyzed. Owing to locally high concave curvature on the pressure side profile, the double shock wave structure was obtained in the turbine passage near the pressure side trailing edge. The first incident shock does not induce the boundary layer separation. The second strong incident shock transmits from the trailing edge of the pressure side and reaches the suction side of the adjacent blade. Strong interaction between the suction side boundary layer and incident shock wave exists in this region, and the separation bubble appears in the no jet case. The complex shock wave system and corresponding flow characters are analyzed.
Due to the complex vortical structures on the blade suction surface with suction side jet, the pressure distribution on the suction side changes, and the shock wave system in the transonic turbine passage is rearranged, thereby influencing the shock wave boundary layer interaction. The separation onset decays with the suction side jet, and it keeps move downstream with increasing jet velocity. Length of the separation bubble is significantly reduced with suction side jet. However, when the jet velocity is beyond a certain value, the effect of suction side jet will not improve. The complex vortical structures with suction side jet will reenergizing to the low momentum fluid within boundary layer, and the mean velocity profiles in the boundary layer near the shock wave boundary layer interaction religion with suction side jet are more solid than the no jet case, which infers stronger resistance to flow separation. Complicated vortical structures exist near jet region, the Kelvin–Helmholtz instabilities of the shear layer of the jet flow and its coherent structures dominate the unsteadiness of the suction surface. The incident shock wave enhances the pressure fluctuation in the SBLI region, whereas the effect concentrates only on the first harmonic of the K-H instability but not higher frequencies.
Numerical Study of Influence of Rotor Tip Gap Increase due to Age Deterioration in 3-Stage Gas Turbine
Authors: Yonezawa Koichi , Sakamoto Junichi , Sugiyama Kazuyasu , Ohmori Shuichi , Umezawa Shuichi 
Published: January 2021

Abstract
Influences of age-related deterioration on the increase in rotor tip gap width are discussed numerically. In the gas turbine examined in the present study, there are two kinds of geometries around the rotor blade tip. In the first stage, there is clearance between the blade tip and the casing without any seal structures. On the other hand, there is a shroud and seal fin on the rotor blade tip. The blade geometries were measured using a 3-D scanner in a working power plant, and the tip clearances were varied by changing the casing contour. Steady-state CFD simulations were carried out. Tip gap widths were varied by shifting the casing wall. For simplicity, the blade geometries were not changed. The influence of tip clearance was examined by changing the geometries in each stage separately. Boundary conditions were determined using the previously developed hybrid method of heat balance analysis and CFD simulation, which can simulate the operating conditions of a working gas turbine. The results showed that the turbine performance degradation could spread to the following stage. Observation of entropy fields revealed that the increase in the tip leakage flow affected the flow in the following nozzle, and the loss increased.
An Experimental, Aerodynamic Evaluation of Design Choices for a Low-Pressure Compressor Transition Duct
Authors: Walker A. Duncan , Mariah Ian , Hall Chris 
Published: January 2021

Abstract
The S-shaped duct which transfers flow from the low-pressure fan to the engine core of modern large civil turbofans presents a challenging design problem. Aerodynamically it must accommodate a spatially and temporarily non-uniform inlet in conjunction with a complex flow field which will develop under the combined influence of pressure gradients and streamline curvature. It must also allow for the transfer of structural loads and services across the main gas path. This necessitates the use of structural vanes which can compromise aerodynamics, introduce unwanted component interactions and erode performance. Furthermore, this must all be achieved with minimum length/weight and without flow separation. This paper presents a comprehensive aerodynamic evaluation of three options for a low-pressure compressor transition duct containing (i) a long-chord, structural compressor outlet guide vane, (ii) a more aerodynamically optimal but non-structural outlet guide vane in conjunction with a small number of discrete radial load bearing struts and (iii) a fully integrated outlet guide vane and strut design. Evaluation was performed using a fully annular, low-speed test facility incorporating a 1 ½ stage axial compressor and transition duct representative of an engine design. Aerodynamic data were produced from miniature five-hole probe area traverses conducted at several locations with compressor/duct. The data suggest that all the options were viable. However, the aerodynamic vane and discrete struts produced the lowest system loss with the other two options being comparable. The performance of the structural vane was seen to be sensitive to off-design conditions producing a notably increased loss at a low flow coefficient. The more optimized aerodynamic vanes were much less sensitive to off-design conditions whilst the fully integrated design showed only very small changes in loss.
A Shape-Morphing Subsystem for Small Wind Energy Conversion Systems
Authors: Jauregui Juan , Herbert Francisco , Castillo Krystel 
Published: January 2021

Abstract
The purpose of the present document is to describe a design proposal for a flexible blade that can adapt its aerodynamic profile and fulfill the “Shape-Morphing concept.” The design is based on the analysis of the geometrical changes that a specific baseline aerodynamic profile must undergo during the shape-morphing process to another aerodynamic profile. The concept design assumes that the arc length of the aerodynamic profiles remains constant; therefore, the cord length changes from one configuration to the other. The proposed mechanism deforms the baseline profile in a way that it assures a continuous path between the aerodynamic forms. To demonstrate the effectiveness of the proposed mechanism, a flexible blade prototype was constructed and tested while morphing from a NACA 0012-based shape to a NACA 4412-based shape. The experimental results indicate that it is possible to implement a shape-morphing mechanism within small wind turbine blades that is able to accurately modify their geometrical shape and, thus, their aerodynamics, providing a novel alternative for control and operation optimization.
Autoregressive Bayesian Hierarchical Model to Predict Gas Turbine Degradation
Authors: Losi Enzo , Venturini Mauro , Manservigi Lucrezia 
Published: January 2021

Abstract
Gas turbine industry currently implements prognostic and health management systems as a fundamental task to predict the deteriorated characteristics of a gas turbine at future states and in turn plan maintenance actions. Thus, economic losses caused by system breakdowns and unnecessary repair actions can be reduced.
In this work, a data-driven Bayesian Hierarchical Model (BHM) is implemented by means of an innovative autoregressive structure to predict gas turbine progressive deterioration. The novel autoregressive model provides an estimate of the output variable which depends on time and its previous values.
In such a model, lagged values of the output are used as predictor variables. The autoregressive BHM, called ARBHM in this paper, is applied to highly heterogeneous field data taken from the literature, characterized by different degradation rates and referred to the power output of a large-size heavy duty gas turbine.
The ARBHM tested in this paper includes up to a third-order lag and is compared to a BHM that only uses time as the regression variable. The comparison is carried out by performing both single-step prediction and multi-step prediction of power output. The results demonstrate that, in the considered degradation scenarios, the innovative ARBHM is usually preferable to BHM, since prediction errors decrease up to 2.0 % in the best case.
Employing Space-Based Hyperspectral Imagery for Pipeline Leak Prevention, Detection and Compliance
Authors: Weaver R. Peter , Katz Dan , Prabahakar Tushar , Corcoran Katie A. 
Published: January 2021

Abstract
We are now living in what has been described as the Experience Era, where lines between the digital and physical are increasingly blurred. As such, we are just beginning to see how customized access to space will improve asset stewardship in ways that are still evolving, as customization of on-orbit technology pushes the bounds of how we receive and process information.
Specific to oil and gas operators, one technology being launched by microsatellite, hyperspectral imagery (HSI), is poised to enable unparalleled daily global pipeline leak prevention, detection and speciation, intrusion and change detection capabilities. This will replace conventional DOT pipeline patrol for compliance while contributing to our understanding of vapor emissions as regulated by the Environmental Protection Agency. This paper discusses both the evolving space marketplace and the state of the art for HSI, including current examples of hyperspectral findings regarding pipeline and terminal leaks.
Successful deployment of HSI will drive a decrease in the number and magnitude of pipeline leaks using persistent, global, high-resolution data collection, rapid and reliable analysis, and immediate reporting of actionable information.
For decades, satellite HSI technology has offered a promise of remote hydrocarbon detection and other features of interest. It is only now becoming scalable, accessible to, and cost-effective for the pipeline industry, and thus a reality for cost-effective pipeline stewardship.
An Empirical Fracture Control Model for Dense-Phase CO2 Carrying Pipelines
Authors: Michal Guillaume , Østby Erling , Davis Bradley J. , Røneid Sigbjørn , Lu Cheng 
Published: January 2021

Abstract
The control of a running ductile fracture in dense-phase CO2 carrying pipelines requires noticeably better fracture resistance than that typically required for the transport of lean or rich natural gas. The long saturation plateau of the decompression sustains a significant driving force at low fracture velocities.
Since 2012, at least four independent projects published data to better understand the applicability of the Battelle Two-Curve Method for CO2 transportation, provide insight on minimum toughness requirements and margins of safety. Nine full-scale propagation tests were executed across these projects. About 50 pipes had interactions with a running ductile fracture, 33 pipes supported the propagation of the fracture over their entire length, the other 17 pipes stopped the fracture.
The original BTCM is not considered applicable with dense-phase CO2. Despite the actual decompression velocity’s saturation plateau decreasing with velocity, and despite the pressure at the crack tip being typically 8 bar lower than predicted, the model can be significantly non-conservative. Correction factors on toughness and arrest pressure are required.
An empirical model for prediction of the minimum required toughness is proposed. It is supported by the data from the four aforementioned projects. The details and the limitations of the database are presented. The arrest boundary is expressed graphically in the frame commonly used to present the NG18 arrest pressure boundary.
A discussion on the location of the experimental data points relative to the arrest-propagation boundary is given. It supports the definition of three regions of interest: a region of likely propagation, a region of likely arrest, and a transition region between these two, where the boundary resides.
All current standard and recommended practices have seemingly similar gaps with respect to the control of a running ductile fracture. The empirical model brings along a set of recommendations and requirements to consider in the context of dense-phase CO2 applications.
Improved Surface Loading Stress Analysis Method Considering Protection Measures
Authors: Zhang Shenwei , Zhang Ken , Pino Maria , Law Jonathan , Matchim Tammie 
Published: January 2021

Abstract
This paper presents a methodology to evaluate pipe stress induced by surface vehicle loading at uncased road crossings that are protected by mat or bridging. When vehicles cross an existing pipeline, additional circumferential and longitudinal pipe stresses induced by surface vehicle loadings should be comprehensively considered to ensure pipe integrity and safe operation. Surface protection measures are sometimes installed to distribute the surface loading away from pipe centerline and reduce “footprint pressure”. A modified CEPA equation was proposed to calculate the radius of relative stiffness (or effective length) of mat and was validated by comparing with results from continuum FEA. The effective length calculated by the modified equation demonstrates good consistency with the FEA-predicted effective length. An approach was proposed to evaluate the pipe stress with user-defined free span of bridging, which provide flexibility for optimizing bridging protection in the field. A tool was developed to facilitate the assessment of surface loading stress of pipeline with mat or bridging protection.
Case studies were presented to demonstrate the application of the proposed methods and the effect of mat thickness or bridging free span on the reduction of live load stress. The proposed methods will benefit pipeline operators with derived cost-effective protection measures for vehicle crossing while assuring safety of pipeline operation.
Incorporating Inline Inspection Internal Measurement Unit Data Analysis Into Integrity Management Programs
Authors: Dewar Doug 
Published: January 2021

Abstract
Inline Inspection Internal Measurement Unit (ILI IMU) data analysis is a well understood but often under-utilized technology for detecting, defining, assessing and monitoring soil to pipeline interactions. The technology has been successfully used to detect landslide interactions since 1996 [1]. Operators can be provided with a vendor analysis (initial bending strain or run to run movements) and/or processed raw data for either internal or third-party raw data Analysis [2]. Vendor Analysis typically identifies major soil/pipeline interactions but primarily reports dig related settlements [3] and static construction related features. Raw data analysis is typically used to define interactions and provide detailed pipe shapes and deformations within targeted pipeline segments.
An approach for determining ILI IMU analysis/data requirements for individual ILI run segments for any size of pipeline system is presented. Guidelines for analysis are provided for Operators to optimize efforts based on the hazards encountered in individual pipelines or pipeline systems. The process includes feature screening, integrity/geotechnical specialist review and risk control/mitigation measures, if required.
To facilitate the feature screening process, a classification system for ILI IMU features is presented based on their type, activity and source modified from the system presented in [3].
Integrity Validation of Small Diameter-Thin Wall Pipeline Susceptible to Cracking or Crack-Like Indications: A Case Study
Authors: Parsibenehkohal Nima , Ilbagi Arash , Tatarov Alex , Gareau Frank 
Published: January 2021

Abstract
The integrity validation of small diameter, thin wall pipelines can be challenging. In-line inspection tool limitations for diameters below approximately 4.5-inch contribute significantly to this challenge. This paper will describe experiences related to the successful integrity validation of a 3-inch vintage high vapour pressure (propane) pipeline which was susceptible to external cracking as well as crack-like indications at the seam weld (e.g. hook cracks and lack of fusion). This line pipe was manufactured in 1967 with a low frequency electric resistance welding (ERW) process. The major threat was identified to be external corrosion since external metal loss up to 70% of the wall thickness was reported by in-line inspection (ILI). The cut-out samples obtained from integrity digs following the ILI were examined by magnetic particle inspection methods. Some external features on these cut-out samples were reported as cracks. The pipeline licensee involved Skystone to complete an engineering assessment and provide a short-term and long-term integrity plan to validate the integrity of the pipeline for continued service.
The cut-out samples were re-examined. This examination included cross-sectional metallography of the area suspected to contain crack-like indications. No external cracking was identified; however, crack-like indications such as lack of fusion were found on the ERW seam.
A pressure-spike test was designed as an integrity validation technique and completed successfully. This paper reviews the difference between the pressure-spike test and conventional pressure tests, the technical basis for the pressure-spike test, its limitations, and practical considerations that need to be considered. The regulatory recognition of spike testing as well as available recommended practices that refer to this approach will be discussed.
A long-term integrity plan was developed by establishing an interval for the next pressure-spike test using fatigue life estimation.
Influence of Small Volumetric Flaws on the Measurement of Crack Growth and Tearing Resistance in SENT Tests
Authors: Adriano Vitor , Cardon Eleine , De Waele Wim , Hertelé Stijn , Boone Matthieu 
Published: January 2021

Abstract
This study evaluates the influence of volumetric discontinuities on the SENT tearing resistance curve as measured using DCPD and UC techniques. In order to do that, a series of SENT tests was carried out on specimens containing small drilled holes in different locations to simulate the presence of volumetric weld flaws. In addition, porous welds were produced by robotic Gas Metal Arc Welding (GMAW). Welding parameters were fine-tuned in order to obtain specimens with different porosity levels. Afterward, the pores were characterized by means of X-ray Computed Tomography (CT) scans and their position, shape and location were determined. SENT tests were performed in a servo-hydraulic machine using a double clip gauge set up to measure crack opening and DCPD and UC for crack sizing. The results indicated that volumetric discontinuities can influence the accuracy of crack measurement techniques in particular, and the measured resistance curve as a whole.
An Approach to Establishing Manufacturing Process and Vintage of Line Pipe Using In-Situ Nondestructive Examination and Historical Manufacturing Data
Authors: Switzner Nathan , Veloo Peter , Rosenfeld Michael , Rovella Troy , Gibbs Jonathan 
Published: January 2021

Abstract
The October 2019 revisions to US federal rules governing natural gas pipelines require Operators to establish vintage and manufacturing process for line-pipe assets with incomplete records. Vintage and manufacturing process are considerations when establishing populations of pipe for maximum allowable operating pressure (MAOP) reconfirmation, materials verification, and integrity management programs. Additionally, the rule changes establish an allowance to utilize in-situ nondestructive examination (NDE) technologies to verify line-pipe material properties including strength, composition, microstructure, and hardness.
Economic and market demands have driven changes in steelmaking technologies and pipe-forming approaches. Knowledge of the relationships between processing, microstructure and mechanical properties have been fundamental to the evolution of steel line pipe manufacturing. Product specifications and standards for the manufacture and testing of pipe and tube have crystallized this evolution as performance expectations increased. The resulting manufacturing process changes have left a variety of “fingerprints” observable from in-situ materials verification NDE data, when analyzed holistically.
The purpose of this work is to enable operators to begin leveraging these fingerprints to illuminate the vintage and manufacturing process of their line pipe assets using the NDE data. A method is proposed to re-establish line-pipe asset manufacturing and vintage records using historical line pipe manufacturing practices and NDE materials verification data.