bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods and Apparatus for Real-Time Clearance Assessment Using a Pressure Measurement
Authors: Kim Taehong
Published: October 2022

An aircraft turbine engine is exposed to high temperatures, high pressures, and high speeds, and case structure and rotating parts have different thermal and mechanical expansion and contraction. Most of turbine engines adapts ACC (Active clearance controls) system to manage thermal contraction of casing and control tip clearance automatically during operation. For example, case structure can be cooled and radially contracted by cooling air outside of casing structure and the system is working to minimize the gap and improve turbine performance. However, the current system does not account of blades tip loss progression caused by rub and oxidation. As engine deteriorates on wing, the mismatching error between tip clearance calculation and actual hardware condition is increased and engine efficiency is being worsen.

Real time measurement of tip clearances would be a crucial way to understand tip loss and adjust the gap to maintain turbine efficiency, but current technology of measuring sensors including laser, capacitive, eddy current, and microwave is not applicable for production engines due to technical limitations such as short life, high cost, design complexity, etc. Analytical method using engine parameters is currently being developed, but it has not been validated to apply for accuracy.

This study is to review radial tip clearances and pressure measurement in engine flight test and demonstrate its linear correlation of Pressure Efficiency against clearance changes during test. As a result, it proposes new methods for tip clearances evaluation based on pressure measurement and conversion curves. New methods include one-point, two-points and three-points (or multi-) pressure measurement to assess clearance changes for different operating conditions. The conversion curves would be developed during engines tests on different power levels and be applicable for production engines with low cost, longer life, efficiency improvement and so on.
Technoeconomic Comparison of sCO2 and ORC Systems for Waste Heat Recovery
Authors: Allison Timothy C. , Wilkes Jason C. , Wygant Karl , Pelton Robert
Published: October 2022

Various supercritical carbon dioxide (sCO2) power cycles are an emerging bottoming cycle technology for gas turbine waste heat recovery with potential advantages relative to Organic Rankine Cycle (ORC) systems, including improved performance, compactness, improved economics, nonhazardous working fluids, and faster ramp capabilities. This work compares a waste heat recovery system based on an integrally geared compander in a sCO2 preheat cycle configuration with split recuperator with a recuperated ORC in the literature. The integrally geared system is comprised of an 1800 rpm generator with high-pressure and low-pressure pinions splitting a two-stage compressor and expander. Cycle constraints and design drivers, and optimization of the sCO2 system are described, along with current technology readiness and full-pressure full-temperature opera ting experience of the various components including compressors, expanders, heat exchangers, and other system components. Both cycles are paired with a commercial 15 MW gas turbine, and the resulting system costs, performance, and other attributes are presented. The cycles are compared with an cold-side temperature of 35 °C, showing an ORC system output of 5066 kW and an sCO2 system output of 5660 kW, i.e. an 11.7 % performance benefit for sCO2. Additionally, cost and size requirements and costs for the sCO2 and ORC-based systems are compared, indicating comparable nominal costs for both systems and a potentially lower cost for sCO2 systems, particularly when an indirect heat transfer loop is needed.
Analysis of sCO2 Waste Heat Recovery System for Application in a Cement Plant
Authors: Vesely Ladislav , Macadam Scott , Kapat Jayanta , Subbaraman Ganesan
Published: October 2022

The industrial sector contributes approximately 28% of global CO2 emissions. CO2 emissions from energy-intensive industries can be reduced by converting waste heat into electricity. This represents a low-cost, zero-emissions power generation option with near-term deployment opportunities. One energy-intensive industry is cement production. Two cement plant heat sources are flue gas streams from preheater and clinker cooler, with temperatures of 250–450 °C. Potential energy conversion systems include Organic Rankine (ORC), steam Rankine (SRC), and supercritical CO2 (sCO2) power cycles. ORC/SRCs have been commercially deployed in cement plants. However, sCO2 power cycles offer benefits such as high thermal stability of CO2, higher cycle efficiencies, and compact power generation equipment. The paper is focused on multi-objective optimization of four sCO2 cycle layouts (Recuperated, Re-compression, Partial recuperative, and cascade) and comparison with ORCs/SRCs. The optimization considers waste heat temperatures of > 300°C. The results show that sCO2 power cycles can reach cycle efficiencies up to 30 %, which is higher than corresponding ORCs and almost similar to SRCs. However, cycle efficiency is not the only parameter to evaluate waste heat utilization. More meaningful parameters are the net power and capital costs. Results show higher power outputs from the sCO2 cycle compared to ORCs and SRC.
Optimization of the Traveling Time of Construction Crews to Minimize the Time to Operation of a Wind Farm
Authors: Ferrari Lorenzo , Frate Guido Francesco , Leanza Francesca , Giuliattini Burbui Gian Lorenzo
Published: October 2022

Building a wind farm is a long and critical process. Many operations have to be arranged in sequence to complete and put in operation a wind farm. Typically, a wind farm is located in an exposed site, with a reduced accessibility and a limited interconnections between machines. The number of crews operating in parallel on the plant is a crucial parameter. By increasing the number of teams, the time to operation decreases but the overall commissioning cost increases. The strategy adopted to schedule the building operations can have an impact on this balance. An optimized sequence may keep the time to operation low but still limiting the number of crews involved. In this study, an optimization procedure based on a genetic algorithm was used for the minimization of the construction time of a wind farm of 200 MW selected as a case study. The problem was solved by considering an approach inspired to the Multiple Travelling Salesman Problem. An increasing number of crews was also considered to find the tradeoff between time and cost. The comparison between the results of the optimization process and those of a more traditional approach showed the benefits of an optimized approach to the problem both in terms of time to operation and costs. In particular, in the case study analyzed, a saving of almost 24% of the erection and installation time (around 280k$) was achieved only by optimizing the routes followed by the construction crews.
Experimental and Computational Investigation of an Advanced Casing Treatment in a Single Stage High Speed Compressor
Authors: Maher Nicholas H. , Ross Mark H. , Morris Scott C. , Priebe Stephan , Jothiprasad Giridhar , Allan David , McNulty G. Scott , Macrorie Michael
Published: October 2022

An advanced casing treatment design, in the form of bent-axial slots applied to the casing near the rotor leading edge, was tested in a single stage high speed axial compressor. Compressor performance and stall margin measurements were acquired for both casing treatment and for the smooth wall case at four different corrected speeds. The measurements also included rotor-exit radial traverses of unsteady total pressure. The results indicated an increase in rotor pressure ratio at all operating conditions with the application of the casing treatment. The stall margin also increased at all rotor speeds. Efficiency increases were observed with the casing treatment at design conditions and some off-design conditions.

Numerical simulations of the IGV, rotor, and stator were conducted with and without the casing treatment. These results served to validate the efficacy of the part-wheel Unsteady Reynolds-averaged Navier-Stokes (URANS) simulations to predict the effects of the casing treatment. The simulations also allowed a detailed study of the flow physics related to the interactions between the rotor and casing.
Residual Strength of Turbine Grade Ceramic Matrix Composites After Being Subjected to Solid Particle Erosion at Elevated Temperatures
Authors: Mirza Farhan , Panakarajupally Ragav P. , Morscher Gregory N. , Abdi Frank , Choi Sung
Published: October 2022

A preliminary study towards understanding the effects of elevated temperature hard particle erosion on remaining strength in ceramic matrix composites was initiated. Oxide and non-oxide ceramic matrix composites were subjected to erosion using alumina particles under a combustion environment at 800 and 1200°C. Eroded specimens were observed under optical microscopy capable of 3D depth scanning to understand the extent of erosion damage. The eroded specimens were then subject to room temperature tension test to evaluate the retained properties. The results indicate that erosion rate increases with an increase in particle velocity and temperature. Residual strength tests indicate that specimens impacted at higher velocity and temperature showed lower tensile strength due to increasing crater depth.
Characterization of Properties of Laser Powder Bed Fusion 3D-Printed Inconel 718 for Centrifugal Turbomachinery Applications
Authors: Lea Hannah G. , Wooding Rochelle S. , Kuhr Sam , Rotella John , Córdova José Luis
Published: October 2022

This paper presents the results of a comprehensive effort to characterize the properties of Inconel 718 produced by a form of laser powder bed fusion (LPBF) additive manufacturing (AM) or 3D-printing, subsequently subjected to hot isostatic pressing (HIP) and heat treatment according to standards F3055-14a and AMS 5663, respectively. Material property data, while broadly available for traditional Inconel 718 presentations (e.g. forgings or castings), is currently lacking for the 3D-printed material.

It is expected that while limited in size, the experimental data sets presented provide sufficient information to glean the capability of LPBF Inconel 718. These include: 1) Chemical composition, electron backscatter diffraction (EBSD), and x-ray energy dispersive spectroscopy (XEDS) characterization of 3D-printed material structure; 2) Tensile properties — 0.2% yield stress, ultimate stress, modulus of elasticity, and elongation to failure — based on 108 samples, as functions of temperature and sample print orientation; 3) Creep rupture data including the Larson-Miller parameter, based on 21 samples; and 4) High cycle fatigue data based on 21 samples as a function of temperature.

Results are compared to available standards and/or data for forged, cast, and other AM Inconel 718. A key observation of this study, based on the EBSD results, is that while the material appears to approach full recrystallization following heat treatment, there is a detectable fraction of the material that does not fully recrystallize, resulting in a material with mechanical properties (e.g. yield stress, creep rupture) measurably lower than those of forgings, but higher than those of castings.
Additive Manufacturing of Centrifugal Impellers for Solid Oxide Fuel Cell Anode Offgas Recycle Blowers
Authors: Córdova José Luis
Published: October 2022

A form of laser powder bed fusion (LPBF) 3D printing has been used to manufacture the impellers of anode offgas recycle blowers (AORBs) for solid oxide fuel cell (SOFC) applications. The material selected is Inconel 718, since it can endure the conditions and temperature ranges in which these systems typically operate. This paper presents details of the multiple process trials and the issues resolved to achieve a successful build, demonstrating the feasibility of the method for impeller manufacturing. Also discussed are the potential cost and design flexibility benefits that may be derived from 3D printing methods, particularly during integration of prototype and low count turbomachinery production runs. The paper discusses long-term goals of the project to support the reduction of cost of SOFC power plants by reducing the cost of balance of plant (BOP) subsystems, from design to integration.
Turbulence Characteristic and Loss of Transonic Turbine Tip Leakage Vortex With Endwall Motion Effect
Authors: Zhou Kai , Zhou Chao
Published: October 2022

Tip leakage flow is considered as an essential loss source within unshrouded high-pressure turbines. This work numerically investigated the flow physics associated with the prediction of the tip leakage loss in a transonic turbine cascade at a high Reynolds number. The instantaneous flow pattern predicted by delayed detached eddy simulation (DDES) shows that the dominating frequency of the tip leakage vortex from its initial generation to further downstream development varies slightly. However, with endwall motion, the scraping effect enhances the horseshoe vortex, and suppresses the tip leakage vortex within a smaller corner region. The dominating frequency of the tip leakage vortex varies significantly. After its breakdown, it spreads to a broad range of frequencies with much higher fluctuation velocity. This indicates that the evolution of tip leakage vortex in the endwall motion case is highly unstable, and anisotropic turbulence occurs. The Reynolds stress components are also investigated to show that vortex breakdown and turbulence characteristics. Besides, two typical Reynolds-averaged Navier-Stokes (RANS) models (Sparlat-Allmaras (SA) model and k-ω shear stress transport (SST) model) are applied to compare the ability in the prediction of the vortex patterns. The results show that in the stationary endwall case, the tip leakage loss is insensitive to turbulence model. However, in the endwall motion case, SST model overpredicts the loss while SA model underestimates the loss. Anisotropic turbulence makes the turbulence modeling cause an evident deviation in loss prediction. The loss prediction is relatively insensitive to the turbulence model in the stationary endwall case, while primarily sensitive in endwall motion case.
Negative Centering Forces of Wet-Gas Hole-Pattern Seals at Low Excitation Frequencies
Authors: Zhang Min , Childs Dara W.
Published: October 2022

Zhang and Childs (2021) investigated the behaviors of a hole-pattern seal (hole depth Hd = 1.9 mm) under wet-gas conditions. The hole-pattern seal’s rotordynamic coefficients were strongly frequency-dependent. Direct stiffness K increased as excitation frequency increased and was close to zero at low excitation frequencies. Cross-coupled damping c was negative and could reduce the seal’s net centering force. The net centering force can be represented by effective stiffness Keff. This paper calculates the Keff values of the seal presented by Zhang and Childs (2021) and finds that Keff decreases after adding oil to the air and changes from positive to negative in some cases. This paper also presents the test data for a new hole-pattern seal that has the same geometric dimensions except with a deeper Hd of 2.5 mm. Tests for the new seal are performed at 62.1 bars inlet pressure, 0.5 pressure ratio, three speeds from 10 to 20 krpm, and two inlet liquid volume fractions LVFs (zero and 2%). As Hd increases from 1.9 mm to 2.5 mm, Keff decreases, especially at low excitation frequencies. The new hole-pattern seal shows negative Keff values at low excitation frequencies. The negative Keff of the new hole-pattern seal at low excitation frequencies can lead to large negative centering forces and prevent testing for cases with inlet LVF higher than 2%. Predictions are produced by using San Andrés’s (2011) 2-phase bulk-flow model and compared with experimental results.
Numerical Investigations of Flow Structures in Radial Rim Seal and a Modification of the Orifice Model
Authors: Xue Qichao , Li Xueying , Ren Jing
Published: October 2022

Under the increasing turbine temperature of gas turbine, the thermal bearing capacity of rotor and stator of turbine is increasingly limited, which poses a more severe challenge to the protection means such as rim seal, and requires more detailed estimation of flow and heat transfer of rim seal. One of the most important parameters in the estimation is the sealing efficiency. The Orifice Model is widely used to simplify the prediction of sealing efficiency of various sealing structures. Its advantage is that different structures can be described by the same model. However, further work is needed in the prediction of sealing efficiency for more complex structures or the high radius of the locations such as the interface between the disc cavity and the main flow.

In this paper, steady numerical simulation is carried out for a radial rim seal structure, and the numerical results are verified by the experimental results in the disk cavity. The flow phenomenon and the mechanism of ingress flow near the rim seal structure is further studied. It is found that the ingress flow has axial and circumferential inhomogeneity, According to the tangential velocity, the ingress flow presents two distinct and “antagonistic” fluids respectively. On this basis, this paper proposes a modification to the Orifice Model, which determine whether the flow is egress or ingress by the tangential velocity. In addition, according to this method, the two-dimensional distribution of the egress and ingress at the interface near the main flow can be seen, and it can be fitted with a simple multi-segment linear function.
Effects of Pure Shearing and Rigid-Body Rotation on the Evolution of Tip Leakage Vortex in an Axial Compressor Rotor
Authors: Liu Yangwei , Zhong Weibo , Tang Yumeng
Published: October 2022

Tip leakage vortex (TLV) in an axial compressor has a considerable impact on aerodynamic performance. Hence, deeper insight should be gained into the evolution mechanism of the TLV. In this paper, the tip leakage flow (TLF) field of a low-speed large-scale axial compressor rotor at both design and near stall conditions by delayed detached eddy simulation (DDES) is analyzed. The swirling flow motion of the TLV is decomposed into three components: rigid-body rotation, pure shearing, and compressing-stretching. The effects of these swirling flow components on the evolution of TLV are investigated. Results show that the shearing and rotational motions of TLF at both design and near stall conditions vary because of the difference in leakage flow conditions. At the near stall condition, the TLV is stronger after its formation but breaks down earlier and changes more violently. Furthermore, the shearing effect plays a significant role in the TLF and prevails over the rigid-body rotation except in the core region of the stable vortex. Most of mechanical energy dissipation is caused by pure shearing. The spiraling pattern and orbital compactness of the TLV are investigated by the local trace criterion-based elliptical region (LTER) method. Results show that the main spiraling pattern of the TLV changes regularly as the TLV develops downstream. In addition, the decrease of the spiraling compactness level reflects the TLV breakdown due to the decrease of swirling strength caused by weaker rigid-body rotation and pure shearing. The swirling flow with high compactness caused by strong shearing effects contributes to the energy dissipation significantly.
Sintering Behaviour of 3d Printed 17-4PH Stainless Steel
Authors: Raju Nandhini , Warren Peter , Subramanian Ramesh , Ghosh Ranajay , Fernandez Erik , Raghavan Seetha , Kapat Jayanta
Published: October 2022

The main aim of the research work is to investigate the sintering behavior and its impact on the material properties of 3D printed 17-4PH stainless steel. The samples were manufactured by the Atomic Diffusion Additive Manufacturing technique, the Metal X system. Cooling holes were printed with the sample in different build orientations giving an overview of the printability and accuracy of the atomic diffusion additive manufacturing (ADAM) technique. Samples were processed by washing, thermal de-binding, and sintering to produce a final solid metal part. Pre-sintered parts, after washing, were tested for chemical composition, roughness, particle size analysis, density, Energy Dispersive X-ray spectroscopy, and microstructure analysis using Scanning electron microscopy (SEM) to understand the material properties. Post-sintered samples were tested for the same tests to understand the sintering impact. A unique conceptual approach and statistical analysis are included in this research. To understand the thermal de-binding and sintering kinetics Differential Scanning Calorimetry (DSC) and Dilatometry (DIL) tests were performed. DSC results gave details about the thermal de-binding and binder information. Dilatometry (DIL) results showed shrinkage over the temperature profile, and significant changes in shrinkages were found above 1250 °C. The results gave an overview of the sintering kinetics and sintering impact of 3D printed 17-4PH stainless steel. This helps decide the optimized thermal debinding and sintering profile to achieve high dense material. It should be noted that this is the first-ever study investigating in detail thermal de-binding and sintering kinetics and its impact on the material properties according to the ADAM technique.
Bearing Diagnostics Using Kurtosis Spectral Correlation Based on Cyclic Modulation Spectrum Estimation
Authors: Mauricio Alexandre , Gryllias Konstantinos
Published: October 2022

Bearings are critical machine components, thus monitoring of their health state is a key point in maintenance strategies for cost reduction and avoidance of unexpected breakdowns. Often, bearings’ signals remain masked below other dominant signatures and noise level. A common practice to enhance the signal to noise ratio of the transient signals due to bearing damages, is to filter around the carrier frequency of the transients and envelope the signal. A key issue is the correct detection of the carrier frequency of interest. This paper proposes a novel bi-frequency method, the Kurtosis Spectral Correlation. The method estimates the Spectral Correlation on the Spectral Kurtosis, instead of the classical Short Time Fourier Transform. This results in removal of the 1st order CS phenomena, while retaining the 2nd order CS impulsive signature in the frequency-frequency. The integration of the full band of the Kurtosis Spectral Correlation is proposed to extract the Kurtosis Enhanced Envelope Spectrum, as it provides a simpler bearing diagnostic tool compared to the analysis of the bi-frequency map. The effectiveness of the proposed method is demonstrated on simulated signals, and validated on an experimental drivetrain setup and on a wind turbine dataset.
A Stochastic and Bayesian Inference Toolchain for Uncertainty and Risk Quantification of Rare Autoignition Events in DLE Premixers
Authors: Yousefian Sajjad , Bourque Gilles , Jella Sandeep , Versailles Philippe , Monaghan Rory F. D.
Published: October 2022

Quantification of aleatoric uncertainties due to the inherent variabilities in operating conditions and fuel composition is essential for designing and improving premixers in dry low-emissions (DLE) combustion systems. Advanced stochastic simulation tools require a large number of evaluations in order to perform this type of uncertainty quantification (UQ) analysis. This task is computationally prohibitive using high-fidelity computational fluid dynamic (CFD) approaches such as large eddy simulation (LES). In this paper, we describe a novel and computationally-efficient toolchain for stochastic modelling using minimal input from LES, to perform uncertainty and risk quantification of a DLE system. More specially, high-fidelity LES, chemical reactor network (CRN) model, beta mixture model, Bayesian inference and sequential Monte Carlo (SMC) are integrated into the toolchain. The methodology is applied to a practical premixer of low-emission combustion system with dimethyl ether (DME)/methane-air mixtures to simulate autoignition events at different engine conditions. First, the benchmark premixer is simulated using a set of LESs for a methane/air mixture at elevated pressure and temperature conditions. A partitioning approach is employed to generate a set of deterministic chemical reactor network (CRN) models from LES results. These CRN models are then solved at the volume-average conditions and validated by LES results. A mixture modelling approach using the expectation-method of moment (EMM) is carried out to generate a set of beta mixture models and characterise uncertainties for LES-predicted temperature distributions. These beta mixture models and a normal distribution for DME volume fraction are used to simulate a set of stochastic CRN models. The Bayesian inference approach through Sequential Monte Carlo (SMC) method is then implemented on the results of temperature distributions from stochastic CRN models to simulate the probability of autoignition in the benchmark premixer. The results present a very satisfactory performance for the stochastic toolchain to compute the autoignition propensity for a few events with a particular combination of inlet temperature and DME volume fraction. Characterisation of these rare events is computationally prohibitive in the conventional deterministic methods such as high-fidelity LES.
Improvement of the Semi-Analytical Model of a Tesla Disc Turbine by the Correction of the Velocity Profile
Authors: Rusin Krzysztof , Hasani Malekshah Emad , Wróblewski Włodzimierz , Rulik Sebastian
Published: October 2022

The paper presents the results of investigations concerning a new analytical model of the flow between the two co-rotating discs. In the elaborated model, an emphasis is put on the different approaches to modelling the radial velocity profile. It was confirmed that its shape deviates from traditional parabolic curves, often assumed in the commonly used models, and is more of a “W-shape”, where the maximal velocity is reached at a certain distance from the wall rather than in the middle of the channel. The Buckingham-Π theorem is utilized to determine the factors influencing the radial velocity profile. Seven dimensionless terms were derived that include geometrical features (the channel height, radii), fluid properties (density, dynamic viscosity), thermodynamic parameters (pressure gradient) and kinematic quantities (tangential velocity, rotational speed). Computational fluid dynamics methods were employed to generate the results for various thermodynamic and geometrical conditions which were used as training data for the neural network to recreate the radial velocity profile. Utilizing Matlab software, the neural network was introduced to the popular analytical model of the flow between the rotating discs. The results prove better agreement with the validation data and also make it possible to assume pressure drop in the flow between the discs. The new model may improve the designing methods of the Tesla turbines as it offers higher precision of the performance prediction.
Detuning Optimization of Nonlinear Mistuned Bladed-Disks
Authors: Capiez-Lernout Evangéline , Soize Christian
Published: October 2022

One major industrial challenge is to consider the detuning as a technological means to reduce the dynamical amplifications induced by mistuning. Due to technological evolutions, the nonlinear geometrical effects induced by the large displacements cannot longer be neglected. Recently, methodologies for the robust analysis of detuned/mistuned bladed-disks in presence of geometrical nonlinearities have been developed. A full analysis of the detuning optimization of mistuned bladed-disks with finite displacements is carried out on a 12 bladed-disk finite element model. The paper is based on a computational methodology previously developed by the authors. It insists on the necessity to carefully optimize all the involved numerical parameters to get the nonlinear mistuned response of each considered detuned configuration with an optimal balance between response accuracy and computational costs. We then have to be very careful with the construction of an adapted scalar quantity of interest for defining the detuning optimization problem. Direct computations allowing for all possible detuned configurations to be considered allow for obtaining a full data basis. A meticulous post-processing shows the existence of a few detuned configurations, that inhibits the mistuning amplification effects of the pure mistuned bladed-disk.
Preliminary Analysis of High-Temperature Corrosion of Metallic Alloys With CO2 and CO2-Based Working Mixtures for Power Plants Applications
Authors: Putelli Lorenza , Di Marcoberardino Gioele , Gelfi Marcello , Invernizzi Costante Mario , Iora Paolo Giulio , Manzolini Giampaolo
Published: October 2022

CO2 has been proposed in the past decades as a suitable working fluid in power plants. One way to reduce costs is to use carbon dioxide blends instead. There is a lack of knowledge about the behavior of sCO2 blending in the interaction with commercial alloys at high temperatures, so this aspect must be strictly considered. A preliminary study has been performed considering the oxidation behavior of some Ni-based and Fe-based alloy (i.e., alloy 625, AISI 304, and AISI 316) in different conditions. In each case, the oxidation layer developed on the alloy surface was investigated by scanning electron microscope (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). The analysis was also performed on the cross-section of the sample to evaluate the penetration depth of damage. The results show that the interaction with fluorine-containing compounds is more corrosive than pure CO2. This confirms that although the mixture improves the thermodynamic efficiency of the cycle, their compatibility with materials must be carefully investigated. However, in all the cases studied, in the test conditions, the preliminary analysis doesn’t recommend the use of the tested materials.
A Method to Describe the Alignment Between Renewable Power Supply and Demand in Order to Derive Storage Needs
Authors: Reichert Arnd
Published: October 2022

In times, when power generation exceeds demand or prices are low, excess energy can be stored for later use. The stored energy is used in the opposite case when power consumption exceeds generation.

For an energy system where, renewable energy is targeted to be the main source of power generation on our way to carbon neutrality, it is important to understand how much energy needs to be stored to maximize the direct and domestic utilization of the generated energy and thus, to minimize the amount of imported and exported energy. The needed capacity of an energy storage device depends on how well the renewable power generation and consumption are aligned over time. Hence, a description of the alignment between the power generation of renewable energy sources and the power consumption is key to understand energy storage capacity needs.

In this paper a simple method to describe power consumption / consumption alignment and how to derive storage capacity needs from this description is presented. The method can be applied to existing supply / demand data or to simulation results to reduce the simulation effort. The effects of capacity modifications to a power generation and storage system can be easily analyzed. The method can be widely applied to a single project or to an entire nation-wide energy-system, to analyze time periods from a day to a month or a year.

The application of the method is shown by three examples: The first one is a photovoltaic system with a battery storage of different sizes and over different time periods. The second and third example is the renewable energy system of a whole country. The results of the method and the limits of the application of the method are discussed.
Impact of Inlet Conditions on Performance of a Supercritical CO2 Centrifugal Compressor
Authors: Jiang Xudong , Wang Zhiheng , Xi Guang
Published: October 2022

The centrifugal compressor is one of the core components in a supercritical carbon dioxide (SCO2) Brayton cycle, in which the inlet state is near the critical point of CO2 to reduce the compression work. However, the thermodynamic properties of CO2 change dramatically near the critical point. Therefore, the performance and flow in a SCO2 compressor will be sensitive to the variation of inlet conditions. In this paper, a centrifugal compressor stage designed by the in-house code for a 20MW supercritical CO2 Brayton cycle is numerically investigated with the variation of considered inlet state point. Firstly, to take account of the nonlinear variation of the properties near the critical point, the accuracy of look-up table of CO2 properties is evaluated and implemented into the commercial CFD software. Then, the effect of small change in inlet temperature or pressure near the critical point on the compression process and performance is investigated, and the flow fields in compressor with different inlet states are compared. It is shown that the CFD-predicted compressor performance is highly sensitive to the resolution of look-up table as well as the inlet conditions. Slight increase in inlet temperature or inlet pressure will cause a significant decrease in pressure ratio. The impact of small change of inlet state on the flow structures are mainly concentrated on the first half of impeller blade passage.
From Pressure Time Series Data to Flame Transfer Functions: A Framework for Perfectly-Premixed Swirling Flames
Authors: Ghani Abdulla , Albayrak Alp
Published: October 2022

We present a two-step optimization (TSO) framework, which uses the pressure data of an unstable combustion process to estimate the complex-valued Flame Transfer Function (FTF). From the pressure time series, we obtain the instability frequency and the amplitudes of the pressure fluctuations. The first optimization step is based on an acoustic network model of the combustor: the TSO approach makes use of the pressure data to find a simplified n-τ model, which reproduces the unstable combustion process. This step has already been validated for the Rijke tube, a laminar and a turbulent flame in Ghani et al. J. Eng. Gas Turb. and Power 142 (12) 2020. The major contribution of this work adds a second optimization loop to extend the n-τ model to the complex-valued FTF: the gain and phase obtained by the n-τ model are used to fit a distributed time delay model based on the work of Komarek & Polifke, J. Eng. Gas Turb. and Power 132 (6) 2010. Our proposed method is applied to a turbulent, premixed, swirl-stabilized flame operated at two power ratings (SI30kW and 70kW) and two swirler positions. The model results for the FTFs are compared against experimentally measured FTFs for these four configurations and all agree well. To the best of our knowledge, this is the first attempt to estimate the complex-valued FTF solely based on pressure measurements. Compared to classical methods for FTF determination such as experimental tests or numerical simulations, our TSO approach is fast and accurate. The proposed framework is suitable for perfectly-premixed flames stabilized by a swirling flow field, requires two pressure sensors placed at distinct axial locations and is easy to implement.
Ammonia as an Aircraft Fuel: Thermal Assessment From Airport to Wake
Authors: Otto Marcel , Vesely Ladislav , Kapat Jayanta , Stoia Michael , Applegate Nicholas D. , Natsui Greg
Published: October 2022

Over the past two decades, zero-emission aviation initiatives have focused on using drop-in biofuels and sustainable aviation fuels (SAF) to replace fossil-based jet fuels to achieve near-term reductions in carbon emissions with minimal impacts on the global aircraft fleet and supporting infrastructure. While significant advances have been made in the production of such fuels, scaling up manufacturing capability to provide cost-competitive drop-in fuels has been a challenge.

This paper discusses ammonia as a carrier of electricity-derived, green hydrogen for aviation, with near-zero emission. Ammonia is proposed as both a carrier of hydrogen as fuel and to provide cooling for compressor intercooling and cooled cooling air for NOx elimination and condensation of water vapor in the exhaust to reduce contrail formation. The performance of ammonia with regard to all of these objectives will be evaluated. A detailed analysis of the energetics concerning the flow of ammonia from leaving the airport storage, to the fuel tanks of the aircraft to the wake of the engine will be performed. Conclusions will be drawn on how ammonia compares to Jet A, SAF, and hydrogen in overall performance as aviation fuel.
Investigation of Unsteady Rotor-Stator Interaction and Deterministic Correlation Analysis in a Transonic Compressor Stage
Authors: Liu Yangwei , Wei Xindi , Tang Yumeng
Published: October 2022

Unsteady blade row interaction (UBRI) has a large impact on performance in high speed axial compressors, thus, the influence of UBRI should be accurately predicted in compressor routine design. In this study, the unsteady rotor-stator interaction in a transonic single stage compressor, NASA Stage 35, is studied by steady and unsteady Reynolds-Averaged Navier-Stokes (RANS) methods. Firstly, the UBRI is analyzed. Periodic separation bubbles on stator suction surface induced by the rotor wake are observed. Comparisons between steady and unsteady results show that the radial distribution of flow angle near the hub and tip region of the stator is strongly influenced by UBRI. Secondly, deterministic correlations are analyzed based on the average-passage equation system (APES). The distribution of deterministic stress, the relationship between harmonics and decay rate of deterministic correlations, and the relationship between spatial correlations and deterministic correlations are analyzed. Results show that a strong non-linear interaction caused by the rotor wake and the stator potential field is found in the rotor-stator gap, and it is responsible for the generation of spatial-time correlation. It is found that the decay rate of deterministic correlation is highly related to the corresponding harmonics. The higher order harmonic owns higher decay rate. Then a modified exponential decay model for deterministic correlation based on harmonics is proposed, and shows a better performance. At last, the anisotropy of deterministic correlations is analyzed using Lumley triangle. Results show that the deterministic stress is highly anisotropic in the stator passage, which could be considered in the modeling if using similar strategy of turbulence modeling.
Mapping nonlocal relationships between metadata and network structure with metadata-dependent encoding of random walks
Authors: Bassolas Aleix , Holmgren Anton , Marot Antoine , Rosvall Martin , Nicosia Vincenzo
Published: October 2022

Integrating structural information and metadata, such as gender, social status, or interests, enriches networks and enables a better understanding of the large-scale structure of complex systems. However, existing approaches to augment networks with metadata for community detection only consider immediately adjacent nodes and cannot exploit the nonlocal relationships between metadata and large-scale network structure present in many spatial and social systems. Here, we develop a flow-based community detection framework based on the map equation that integrates network information and metadata of distant nodes and reveals more complex relationships. We analyze social and spatial networks and find that our methodology can detect functional metadata-informed communities distinct from those derived solely from network information or metadata. For example, in a mobility network of London, we identify communities that reflect the heterogeneity of income distribution, and in a European power grid network, we identify communities that capture relationships between geography and energy prices beyond country borders.
Ribosome changes reprogram translation for chemosurvival in G0 leukemic cells
Authors: Datta Chandreyee , Truesdell Samuel S. , Wu Keith Q. , Bukhari Syed I. A. , Ngue Harrison , Buchanan Brienna , Le Tonqueze Olivier , Lee Sooncheol , Kollu Swapna , Granovetter Madeleine A. , Boukhali Myriam , Kreuzer Johannes , Batool Maheen S. , Balaj Leonora , Haas Wilhelm , Vasudevan Shobha
Published: October 2022

Quiescent leukemic cells survive chemotherapy, with translation changes. Our data reveal that FXR1, a protein amplified in several aggressive cancers, is elevated in quiescent and chemo-treated leukemic cells and promotes chemosurvival. This suggests undiscovered roles for this RNA- and ribosome-associated protein in chemosurvival. We find that FXR1 depletion reduces translation, with altered rRNAs, snoRNAs, and ribosomal proteins (RPs). FXR1 regulates factors that promote transcription and processing of ribosomal genes and snoRNAs. Ribosome changes in FXR1-overexpressing cells, including RPLP0/uL10 levels, activate eIF2α kinases. Accordingly, phospho-eIF2α increases, enabling selective translation of survival and immune regulators in FXR1-overexpressing cells. Overriding these genes or phospho-eIF2α with inhibitors reduces chemosurvival. Thus, elevated FXR1 in quiescent or chemo-treated leukemic cells alters ribosomes that trigger stress signals to redirect translation for chemosurvival.
Staphylococcus aureus
skin colonization promotes SLE-like autoimmune inflammation via neutrophil activation and the IL-23/IL-17 axis
Authors: Terui Hitoshi , Yamasaki Kenshi , Wada-Irimada Moyuka , Onodera-Amagai Mayuko , Hatchome Naokazu , Mizuashi Masato , Yamashita Riu , Kawabe Takeshi , Ishii Naoto , Abe Takaaki , Asano Yoshihide , Aiba Setsuya
Published: October 2022

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by inflammation of various organs such as skin, kidneys, bones, and brain and the presence of autoantibodies. Although the cause of SLE is not completely understood, environmental factors, genetic susceptibility, hormone factors, and environmental factors are thought to play essential roles in the pathogenesis of SLE. Among environmental factors, the microbiota are linked to the development of different autoimmune diseases. The microbiota in the nasal cavity and gut are involved in SLE development, but the influence of skin microbiota is still unclear. Here, we demonstrated that epithelial cell–specific IκBζ-deficient (
Nfkbiz
ΔK5
) mice showed spontaneous skin inflammation with increased abundance of
Staphylococcus aureus
on the skin. When
S. aureus
was epicutaneously applied on
Nfkbiz
ΔK5
mice,
Nfkbiz
ΔK5
mice developed SLE-associated autoantibodies, anti-dsDNA antibodies, anti-Sm antibodies, and glomerulonephritis with IgG deposition. Epicutaneous
S. aureus
application significantly increased staphylococcal colonization on the skin of
Nfkbiz
ΔK5
mice with reduced expression of several antimicrobial peptides in the skin. This staphylococcal skin colonization promoted caspase-mediated keratinocyte apoptosis and neutrophil activation, inducing the interleukin-23 (IL-23)/IL-17 immune response by activating dendritic cells and T cells. Furthermore, the subcutaneous administration of anti–IL-23p19 and anti–IL-17A antibodies alleviated the systemic autoimmune response. Together, these findings underscore epithelial-immune cross-talk disturbances caused by skin dysbiosis as an essential mediator inducing autoimmune diseases.
The Ordovician South Mayo Trough, a basin that recorded the passage of a triple junction along the Laurentian margin
Authors: Ryan* Paul D. , Dewey John F.
Published: October 2022

Tectonic models for arc-continent collision can be overly complex where, for example, diachronous sedimentation and deformation along a single plate boundary are attributed to separate tectonic events. Furthermore, continuous sedimentation in a single basin recording a diachronous collision along a plate margin makes it difficult to use classical unconformable relationships to date an orogenic phase. In this chapter, we describe the Ordovician South Mayo Trough of western Ireland, a remarkable example of such a basin. It originated in the late Cambrian–Early Ordovician as a Laurentia-facing oceanic forearc basin to the Lough Nafooey arc. This arc was split by a spreading ridge to form a trench-trench-ridge triple junction at the trench. The basin remained below sea level during Grampian/Taconic arc-continent collision and, following subduction flip, received sediment from an active continental margin. Sedimentation ended during Late Ordovician Mayoian “Andean”-style shortening, broadly coeval with a marked fall in global sea level. These major tectonic events are traced through the nature of the detritus and volcanism in this basin, which is preserved in a mega-syncline. The Grampian orogen is not recorded as a regional unconformity, but as a sudden influx of juvenile metamorphic detritus in a conformable sequence.
Access to HIV healthcare services by farm workers in sub-Saharan Africa (SSA): a systematic review protocol
Authors: Mlangeni Nosimilo , Adetokunboh Olatunji , Lembani Martina , Malotle Molebogeng , Nyasulu Peter
Published: October 2022

Introduction

Sub-Saharan Africa (SSA) region harbours the highest burden of HIV infections in the world. Agricultural work has been reported as one of the occupations with a high prevalence of HIV. Farm workers generally have poor access to health services, which prevents them from receiving proper HIV prevention and care. Furthermore, poor policies and policy implementation, and lack of workplace programmes increases farm workers’ vulnerability to HIV infection. Thus, the aim of this study is to conduct a systematic review to assess HIV prevention and treatment services and national policies governing access to healthcare services by farm workers in SSA.

Methods and analysis

Our systematic review will include studies published from January 1990 to December 2021 within SSA countries. We will use a sensitive search strategy for electronic bibliographic databases and grey literature sources. Databases will include PubMed, CINAHL, Cochrane library, African Index Medicus and Scopus. The main outcomes to be reported will be HIV policy for farmworkers, availability of HIV prevention service(s), availability of treatment and support to farmworkers who are living with HIV, presence of referral structures for farmworkers through the health system and follow-up services for farmworkers who are on antiretroviral therapy. We will synthesise the main characteristics of included studies and use summary measures to describe study characteristics. In a situation where data are not sufficiently homogeneous to perform a quantitative synthesis, we will conduct a narrative synthesis. We will explore themes and relationships between included studies for qualitative data.

Ethics and dissemination

The study will use publicly available data and ethics exemption has been obtained from Human Research Ethics Committees, Faculty of Medicine & Health Sciences, Stellenbosch University. The results of this study will be disseminated through peer-reviewed journals, conference presentations and seminars.

PROSPERO registration number

CRD42021277528.