bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Calculation of Seal Clearance Change in Installation Process of a 1000MW Nuclear Steam Turbine HIP Casing
Authors: Ji Daohui , Mei Ziyue , Jiang Wei , Xiang CaiYan , Xie Danmei , Yue Yanan 
Published: January 2021

Abstract
During installation process, most of 1000MW-class nuclear power steam turbines will undergo certain deformations due to their own big size and heavy weight, which will change seal clearances in the steam passage. The clearance change will affect steam turbine’s efficiency, and may cause rubbing faults and even strong abnormal vibration, affecting the safety of the steam turbine. Moreover, limited by the complex structure and measurement method, it is difficult to measure deformation and seal clearance accurately, so it is necessary to study the change tendency of the clearance in the installation process.
In this paper, a HIP (High and Intermediate Pressure) casing of a 1000MW nuclear steam turbine was taken as the research object, and its 3D geometry model is established based on Pro/E software. By using ANSYS WORKBENCH, we calculated the deformation of the HIP casing during installation with five steps, which are named as: ① lower casing with lower diaphragms, ② step ① + upper diaphragms, ③ step ② + upper casing, ④ step ③ + bolting, and ⑤ replacing the support. Then we analyzed the change of the seal clearance during the installation process by deformation differences of some points under different conditions.
The calculation results show that the maximum deformation of the HIP Casing during the installation process occurs in the middle of casing close to the IP (Intermediate Pressure) casing. The relative change of the clearance during the whole process is 0.6–0.8 mm. The change of seal clearance is largest at the first-stage of IP casing, and it can be 0.8mm during replacement of the support.
Modeling Superposition of Flat Plate Film Cooling Under Complicated Conditions Using Recurrent Neural Networks
Authors: Yang Li , Wang Qi , Rao Yu 
Published: January 2021

Abstract
Film Cooling is an important and widely used technology to protect hot sections of gas turbines. The last decades witnessed a fast growth of research and publications in the field of film cooling. However, except for the correlations for single row film cooling and the Seller correlation for cooling superposition, there were rarely generalized models for film cooling under superposition conditions. Meanwhile, the numerous data obtained for complex hole distributions were not emerged or integrated from different sources, and recent new data had no avenue to contribute to a compatible model. The technical barriers that obstructed the generalization of film cooling models are: a) the lack of a generalizable model; b) the large number of input variables to describe film cooling. The present study aimed at establishing a generalizable model to describe multiple row film cooling under a large parameter space, including hole locations, hole size, hole angles, blowing ratios etc. The method allowed data measured within different streamwise lengths and different surface areas to be integrated in a single model, in the form 1-D sequences. A Long Short Term Memory model was designed to model the local behavior of film cooling. Careful training, testing and validation were conducted to regress the model. The presented results showed that the method was accurate within the CFD data set generated in this study. The presented method could serve as a base model that allowed past and future film cooling research to contribute to a common data base. Meanwhile, the model could also be transferred from simulation data sets to experimental data sets using advanced machine learning algorithms in the future.
Computational and Experimental Studies of Cellular Samples Manufactured Using Additive Methods for Use in Advanced Lightweight Designs of Engine Parts
Authors: Magerramova Liubov , Volkov Michael , Volgin Oleg , Kolos Pavel 
Published: January 2021

Abstract
The use of cellular structures is one way to reduce the weight of engine parts. Cellular structures are used to provide rigidity and strength for parts subject to compression, bending, and shock loads. Failure of the individual elements of a lattice/cell structure does not result in the destruction of the entire part; this stands in contrast to the structure of a conventional homogeneous metal object, in which cracks will continue to increase with increasing load, causing the destruction of the entire part. Lattice/cell structures have relatively high characteristics of rigidity and strength, excellent thermal insulation properties, energy absorption characteristics, and high fatigue resistance. The use of this type of structure in engine part construction opens up new opportunities for advanced aviation applications.
However, the deformation behavior of porous and metallic structures differs significantly from that of conventional homogeneous materials. Samples with cellular and porous structures are themselves designs. Therefore, procedures for strength testing and interpretation of experimental results for cellular and porous structures differ from those for samples derived from homogeneous materials. The criteria for determining the properties of cellular structures include density, stiffness, ability to accumulate energy, etc. These parameters depend on the configuration of the cells, the size of each cell, and the thickness of the connecting elements. Mechanical properties of cellular structures can be established experimentally and confirmed numerically.
Special cellular specimens have been designed for uniaxial tensile, bending, compression, shear, and low-cycle fatigue testing. Several variants of cell structures with relative densities ranging from 13 to 45% were considered. Specifically, the present study examined the stress-strain states of cell structures from brands “CobaltChrome MP1” powder compositions obtained by laser synthesis on an industrial 3D printer Concept Laser M2 Cusing Single Laser 400W.
Numerical simulations of the tests were carried out by the finite element method. Then, the most rational cellular structures in terms of mass and strength were established on the basis of both real and numerical experiments.
Short-Term Optimization of a Combined Cycle Power Plant Integrated With an Inlet Air Conditioning Unit
Authors: Mantilla Weimar , García José , Guédez Rafael , Sorce Alessandro 
Published: January 2021

Abstract
Under new scenarios with high shares of variable renewable electricity, combined cycle gas turbines (CCGT) are required to improve their flexibility, in terms of ramping capabilities and part-load efficiency, to help balance the power system. Simultaneously, liberalization of electricity markets and the complexity of its hourly price dynamics are affecting the CCGT profitability, leading the need for optimizing its operation. Among the different possibilities to enhance the power plant performance, an inlet air conditioning unit (ICU) offers the benefit of power augmentation and “minimum environmental load” (MEL) reduction by controlling the gas turbine inlet temperature using cold thermal energy storage and a heat pump. Consequently, an evaluation of a CCGT integrated with this inlet conditioning unit including a day-ahead optimized operation strategy was developed in this study.
To establish the hourly dispatch of the power plant and the operation mode of the inlet conditioning unit to either cool down or heat up the gas turbine inlet air, a mixed-integer linear optimization (MILP) was formulated using MATLAB, aiming to maximize the operational profit of the plant within a 24-hours horizon. To assess the impact of the proposed unit operating under this dispatch strategy, historical data of electricity and natural gas prices, as well as meteorological data and CO2 emission allowances price, have been used to perform annual simulations of a reference power plant located in Turin, Italy. Furthermore, different equipment capacities and parameters have been investigated to identify trends of the power plant performance. Lastly, a sensitivity analysis on market conditions to test the control strategy response was also considered.
Results indicate that the inlet conditioning unit, together with the dispatch optimization, increases the power plant’s operational profit by achieving a wider operational range, particularly important during peak and off-peak periods. For the specific case study, it is estimated that the net present value of the CCGT integrated with the ICU is 0.5% higher than the power plant without the unit. In terms of technical performance, results show that the unit reduces the minimum environmental load by approximately 1.34% and can increase the net power output by 0.17% annually.
Influence of Key Design Parameters on the Aerodynamic Performance of a Centrifugal Compressor Volute for Turbocharger Applications
Authors: Melani Pier Francesco , Balduzzi Francesco , Bianchini Alessandro , Ferrara Giovanni , Hoffer Pierre-Alain , Montesino Stephane , Brenner Mattia 
Published: January 2021

Abstract
A centrifugal compressor volute should ideally collect the pressurized flow at the diffuser outlet and convey it to the outlet piping as efficiently as possible. The total pressure loss related to the conversion of a radial flow into an axial one, however, is often not negligible, especially for applications where severe dimensional constraints are given, such as in turbochargers applications. Having a reliable tool for the performance prediction of the volute, flexibly adaptable to external constraints, is then pivotal in the design phase of new prototypes.
Within this context, a fully parametric tool has been developed. Based on few geometrical inputs, it allows an automatic generation of both the CAD model of the volute and the numerical setup for the CFD calculation. The shape of the volute cross-section can be fully customized and automatically adapted to the azimuthal distributions of the area and centroid radius given in input by the user. The volute tongue can be also freely modified in terms of shape, azimuthal position and width.
An extensive parametric analysis was then carried out, aimed at investigating the influence of key design parameters needed to define the shape of the volute on the internal fluid dynamics. Particular attention was paid to the tongue modelling strategy and shape, being it the critical feature for the volute flow performance.
As a result, some annotated indications are given to define the first layout of a volute when approaching a new design.
Overall Cooling Effectiveness of Effusion Cooled Can Combustor Liner Under Reacting and Non-Reacting Conditions
Authors: Ahmed Shoaib , Ramakrishnan Kishore Ranganath , Ekkad Srinath , Singh Prashant , Liberatore Federico , Ho Yin-Hsiang 
Published: January 2021

Abstract
Emphasis on lean premixed combustion in modern low NOx combustion chambers limits the availability of air for cooling the combustion liner. Hence the development of optimized liner cooling designs is imperative for effective usage of available coolant. Effusion cooling (also known as full-coverage film cooling) is a common method to cool the combustor liner, which involves uniformly spaced holes distributed throughout the liner curved surface area. This paper presents findings from an experimental study on the characterization of overall cooling effectiveness of an effusion-cooled liner wall, which was representative of a can combustor under heated flow (non-reacting) and lean-combustion (reacting) conditions. The model can-combustor was equipped with an industrial swirler, which subjected the liner walls to engine representative flow and combustion conditions. Inline and staggered arrangement of effusion holes have been studied. These configurations were tested for five different blowing ratios ranging from 0.7 to 4, under both reacting and non-reacting conditions. The experiments were carried out at a constant Reynolds number (based on combustor diameter) of 12,500. Infrared Thermography (IRT) was used to measure the liner outer surface temperature and detailed overall effectiveness values were determined under steady-state conditions. Under non-reacting conditions, the staggered configuration was found to be 9–25% more effective compared to inline configuration. Under reacting conditions, the staggered configuration was be 4–8% more effective compared to inline configuration. It is clear that the coolant-flame interaction for the reacting cases had a significant impact on the liner cooling effectiveness as compared to the non-reacting cases and results in less variation between inline and staggered configurations.
Significance of the Direct Excitation Mechanism for High-Frequency Response of Premixed Flames to Flow Oscillations
Authors: Acharya Vishal , Lieuwen Tim 
Published: January 2021

Abstract
Premixed flames are sensitive to flow disturbances, which can arise from acoustic or vortical fluctuations. For transverse instabilities, it is known that a dominant mechanism for flame response is “injector coupling”, whereby pressure oscillations associated with transverse waves excite axial flow disturbances. These axial flow disturbances then excite heat release oscillations. The objective of this paper is to consider another mechanism — the direct sensitivity of the unsteady heat release to transverse acoustic waves, and to compare its significance relative to the induced axial disturbances, in a linear framework. The rate at which the flame adds energy to the disturbance field is quantified using the Rayleigh criterion and evaluated over a range of control parameters, such as flame length and swirl number. The results show that radial modes induce heat release fluctuations that always add energy to the acoustic field, whereas heat release fluctuations induced by mixed radial-azimuthal modes can add or remove energy. These amplification rates are then compared to the flame response from induced axial fluctuations. For combustor centered flames, these results show that the direct excitation mechanism has negligible amplification rates relative to the induced axial mechanism for radial modes. For transverse modes, the fact that the nozzle is located at a pressure node indicates that negligible induced axial velocity disturbances are excited; as such, the direct mechanism dominates. For flames that are not centered on pressure nodes, the direct mechanism for mixed-modes, dominates for certain nozzle locations and flame angles.
Performance of Darrieus Wind Turbine Using Slotted Blades With Gurney Flap
Authors: Elbaz Ahmed M. R. , Ibrahim Ahmed A. , Mohamed Omar S. , Etman Ahmed K. 
Published: January 2021

Abstract
VAWT such as the Darrieus turbine, could effectively be used in urban spaces. However, the poor self-starting of this type has been considered as a major drawback which limits its application. This also hinders the turbine’s operation at low wind speeds. While the wind energy research community have been lately focusing on augmenting the power coefficient of the Darrieus machines, the enhancement of self-starting capabilities has not attract much attention. In this research, some modifications were applied to the Darrieus type VAWT blades in order to improve its self-starting capability. This entails the application of slotted and Gurney flapped airfoils. The proposed modifications were tested using computational fluid dynamics (CFD) tools. The commercial software ANSYS FLUENT© was used to solve the unsteady Reynolds-averaged Navier–Stokes (URANS) in two dimensions, using two different techniques: the first one is by setting a constant rotational speed for the turbine, and the second one is using the Six Degrees of Freedom (6DOF) solver to calculate the rotational speed during starting due to generated aerodynamic torque on the blades. The proposed airfoil modifications using slot and Gurney flap were applied on Darrieus type VAWT. In a previous study by the authors, the slotted airfoil was shown to enhance the starting torque capabilities, however, the maximum power coefficient decreased, compared to the baseline airfoil turbine. Adding the Gurney flap to the slotted airfoil shows a significant enhancement of the power coefficient throughout the operating range of the turbine. Moreover, the maximum power coefficient of the proposed turbine is also higher than that of the baseline turbine. Further, the self-starting capabilities of the slotted-flapped airfoil turbine has also been remarkably augmented compared to the baseline turbine.
Novel Cyclo-Non-Stationary Indicators for Monitoring of Rotating Machinery Operating Under Speed and Load Varying Conditions
Authors: Mauricio Alexandre , Helm Dustin , Timusk Markus , Antoni Jerome , Gryllias Konstantinos 
Published: January 2021

Abstract
Condition monitoring arises as a valuable industrial process in order to assess the health of rotating machinery, providing early and accurate warning of potential failures and allowing for the planning and effective realization of preventative maintenance actions. Nowadays machinery (gas turbines, wind turbines etc.) manufacturers adopt new business models, providing not only the equipment itself but additionally taking on responsibilities of condition monitoring, by embedding sensors and health monitoring systems within each unit and prompting maintenance actions when necessary. Among others, rolling element bearings are one of the most critical components in rotating machinery. In complex machines the failure indications of an early bearing damage are weak compared to other sources of excitations (e.g. gears, shafts, rotors etc.). Vibration analysis is most widely used and various methods have been proposed, including analysis in the time and frequency domain. In a number of applications, changes in the operating conditions (speed/load) influence the vibration sources and change the frequency and amplitude characteristics of the vibroacoustic signature, making them nonstationary. Under changing environments, where speed and load vary, the assumption of quasi-stationary is not appropriate and as a result a number of time-frequency and time-order representations have been introduced, such as the Short Time Fourier Transform and the Wavelets. Recently an emerging interest has been focused on modelling rotating machinery signals as cyclostationary, which is a particular class of non-stationary stochastic processes. The classical cyclostationary tools, such as the Cyclic Spectral Correlation Density (CSCD) and the Cyclic Modulation Spectrum (CMS), can be used in order to extract interesting information about the cyclic behavior of cyclostationary signals, only under the assumption that the speed of machinery is constant or nearly constant. Global diagnostic indicators have been proposed as a measure of cyclostationarity under steady operating conditions. In order to overcome this limitation a generalization of both SCD and CMS functions have been proposed displaying cyclic Order versus Frequency as well as diagnostic indicators of cyclo-non-stationarity in order to cover the speed varying operating conditions. The scope of this paper is to propose a novel approach for the analysis of cyclo-non-stationary signals based on the generalization of indicators of cyclo-non-stationarity in order to cover the simultaneous and independently varying speed and load operating conditions. The effectiveness of the approach is evaluated on simulated and real signals captured on a dedicated test rig.
The Effects of Specific Heat and Viscosity on Film Cooling Behavior
Authors: Wiese Connor J. , Rutledge James L. 
Published: January 2021

Abstract
For many years, there has been interest in evaluating the effect of density differences between the coolant and the freestream in terms of the cooling effectiveness. Numerous experiments have been conducted with different cooling gases or different temperature gases to evaluate the effect of the density ratio. With little agreement on the best way to scale the density ratio effect, it has become commonplace for some researchers to insist upon matching the density ratio for experimental work.
Unfortunately, the density is not the only property that differs between the various coolant gases used in experiments, and it is certainly not the only property difference between the coolant and the freestream in actual engines. In the present work, we isolate some of these effects through film cooling experiments with carefully selected and conditioned coolant gases at near identical densities but exhibiting other property differences. Most significantly, coolant specific heat varied, but subtle viscosity and thermal conductivity effects were present. Through measurements of the adiabatic effectiveness from a film cooling hole on a leading edge model, we are able to show that the specific heat effect is just as important as the density effect, providing more evidence that effects in prior research attributed to density differences, are actually a combination of density and other property differences.
Generating Laminar Flame Speed Libraries for Autoignition Conditions
Authors: Puduppakkam Karthik V. , Modak Abhijit U. , Wang Cheng , Hodgson Devin , Naik Chitralkumar V. , Meeks Ellen 
Published: January 2021

Abstract
With advanced gas turbine combustor and internal combustion engine designs, autoignition can happen alongside flame propagation. Laminar flame speeds are required to model flame propagation. Determining laminar flame speeds using simulation assumes flames are freely propagating, an assumption that is not valid when autoignition does occur. From a CFD modeling viewpoint however, it is useful to have extrapolated laminar flame-speed values over a wide range of conditions, to allow CFD to operate smoothly and avoid discontinuities while calculating flame-propagation properties. In this work we focus on developing an approach for generating laminar flame-speed libraries under both nonigniting and autoigniting conditions. Following a test of whether autoignition occurs, laminar flame speeds are either modeled or extrapolated. The details of the approach implemented and its validation are explained. We assess the accuracy of the extrapolation employed by calculating relevant coefficients based on flame speeds from nearby operating points. Recommendations are made for the time scales to be used in determining autoignition occurrence. Fuel effects are also explored in this context.