bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Thermo-Hydrodynamic Analysis of the Plain Journal Bearing With Centered Circumferential Groove: Numerical Simulation vs. Experiment
Authors: Zhang Guanghui , Yu Shubo , Liu Zhansheng , Xu Kefan , Li Yu 
Published: January 2021

Abstract
In order to increase the reliability of the oil lubricated journal bearing, the thermal characteristics of the plain journal bearing are investigated and optimized. In this paper, the steady state thermo-hydrodynamic analysis of the plain journal bearing with centered circumferential groove is studied by numerical simulation and experiments. The diameter of the journal bearing is 190mm, and the load of the bearing is 6150N, which is operated with the rotating speed of 5560 r/min. The flow characteristics including the temperature distribution in the clearance of the bearing are simulated by ANSYS CFX, where the Walther viscosity temperature relation and the cavitation effect are considered. The test rig for measuring the pressure and temperature distributing in established, which is driven by electrical motor and certain bearing load can be exerted on it. In the experiments, the temperature distribution of the bearing is measured by 10 temperature sensors, which is arranged on three cross sections along the axial direction. The temperature of the lubricating oil is obtained by the sensors on the shell of the bearing, which is installed in the Babbitt metal. In order to obtain the circumferential distribution of the temperature, the sensors locate at different circumferential angles. The influence of geometrical parameters on the temperature distribution is studied, including the bearing clearance, the bearing length and the groove width by numerical simulation and experiment. The bearing clearance ratios of 1.8‰ and 2.5‰ are compared, and as the increment of the bearing clearance ratio, the temperature of the bearing decreased, which is benefit from the flow mass into the bearing increases. For the bearing length increasing from 90mm to 94mm, the maximum temperature decreases about 3K. For the groove width varying from 20mm to 19mm and 18mm, the temperature of the bearing decreases. The comparison of the numerical results and experiments are presented, and they show similar tendency for the temperature distribution, but the difference of temperature values exists. Based on the results from variation of bearing clearance ratio, bearing length and groove width, the optimized parameters of the bearing are proposed by determining the groove width with 18mm, bearing length with 94mm and the bearing clearance ratio with 2.1‰. The thermo-hydrodynamic analysis from the CFD and the experiments for the optimized bearing are carried out. The results indicate that the thermal performance of the bearing is improved. Compared with original design of the bearing, the maximum temperature is reduced by approximately 5K for optimized design of the bearing.
Development and Application of an Internal Heat-Transfer Measurement Technique for Cooled Real Engine Components
Authors: Ali Asif , Cocchi Lorenzo , Picchi Alessio , Facchini Bruno , Cubeda Simone 
Published: January 2021

Abstract
The aim of this work is to present the development and application of a measurement technique that allows to record internal heat transfer features of real components. In order to apply this method, based on similar approaches proposed in previous literature works, the component is initially heated up to a steady temperature, then a thermal transient is induced by injecting cool air in the internal cooling system. During this process, the external temperature evolution is recorded by means of an IR camera. Experimental data are then exploited to run a numerical procedure, based on a series of transient finite-element analyses of the component. In particular, the test duration is divided into an appropriate number of steps and, for each of them, the heat flux on internal surfaces is iteratively updated as to target the measured external temperature distribution. Heat flux and internal temperature data for all the time steps are eventually employed in order to evaluate the convective heat transfer coefficient via linear regression.
This technique has been successfully tested on a cooled high-pressure vane of a Baker Hughes heavy-duty gas turbine, which was realised thanks to the development of a dedicated test rig at the University of Florence, Italy. The obtained results provide sufficiently detailed heat transfer distributions in addition to allowing to appreciate the effect of different coolant mass flow rates. The methodology is also capable of identifying defects, which is demonstrated by inducing controlled faults in the component.
Prediction of Non-Linear Mechanical Behavior With Deep Neural Network: Application on Low Pressure Turbine Disc
Authors: Jin Yuan , Li Weichen , Yang Zheyi , Jung Olivier 
Published: January 2021

Abstract
Thanks to the increase of computational capacity and the diversification of computational means, deep learning techniques have shown great successes in learning representations from data in the past decade. Following this trend, efforts have been made in the literature to apply Deep Neural Network (DNN) as surrogate model. Common practice consists in utilizing a single DNN to predict a certain physical property given input design parameters, and the DNN is trained by corresponding simulation results. However, most of the complex high-fidelity simulations involve nonlinear physical laws, e.g. elasto-plasticity, which cannot be explicitly depicted by the applied single DNN model. In the present work, static mechanical simulation with nonlinear constitutive law is addressed with a novel approach in a deep learning framework. We approximate the displacement and the nonlinear constitutive law by two deep neural networks. The first DNN acts as a prior on the unknown displacement field, while the second network aims at describing the nonlinear strain-stress relationship. The dependence of the strainstress relationship on the strain level is taken into consideration by taking the first order derivative with respect to spatial coordinates of the first DNN as an input of the second network. A new loss model combining the error in displacement field prediction and constitutive law description is proposed to train the two DNNs together. We demonstrate the effectiveness of the proposed framework on a low pressure turbine disc design problem.
Comparative Assessment of Fouling Scenarios in an Axial Flow Compressor
Authors: Templalexis Ioannis , Pachidis Vasilios , Hasani Azamar 
Published: January 2021

Abstract
It is commonly accepted that fouling degrades severely axial compressor performance. Deposits build up throughout the compressor’s operating life, causing a decrease in its delivery pressure, efficiency and flow capacity. Researchers have also concluded that the presence of wet contaminants and/or high air humidity, plus the quality of air filtration systems, have a far greater impact on fouling rates, than engine specific fouling susceptibility factors [1]. The size of airborne particles ingested into the engine is primarily controlled by the presence of a filtration system. On the other hand, the particle deposition rate and the fouling patterns formed on the blade surfaces are greatly affected by the “stickiness” of the blade surfaces which in turn is affected by the moisture level of the incoming air. Compressor geometry, size and operating point would affect far less the rate of contaminants built up on the wetted surfaces and they would affect even less the exact location on compressor walls and blade surfaces.
The current study identifies four basic operating scenarios which refer to the same compressor, in order to put forward a comparative assessment as to how the factors mentioned above, affect the compressor performance through the fouling mechanism. Scenarios were formed out of the possible combinations regarding the presence of a filtration system and the level of humidity. These were: i) Filtered - dry air, ii) Filtered - humid air, iii) Unfiltered - dry air, and iv) Unfiltered - humid air. These scenarios will eventually reproduce four completely different situations regarding the quality of the incoming air and subsequently, four different fouling regimes for the compressor operating downstream. Data to support the impact of each reported incoming air condition on compressor wetted surfaces, are based on experimental findings collected from a thorough literature review. A fixed operating period was set for all cases.
Prescribed requirements of the computational tool selected to build the compressor model were; i) low computational power since several runs had to be performed in order to cover the assumed time period, and ii) ability to introduce the imprint of various fouling patterns on compressor blades, into the performance of the compressor. SOCRATES, an in-house two-dimensional, streamline curvature-based, through-flow computational tool, meets these requirements and it was used for this study. A fully customizable empirical model, recently introduced in the code, takes into account various aspects of fouling such as the surface roughness level, the flow blockage and the altered deviation angle at the exit of the blade row. A coverage factor was introduced which takes into account the location and the extent of fouling onto the blade surfaces.
Development of Web-Based Short Courses on Control, Diagnostics, and Instrumentation
Authors: Aslanidou Ioanna , Zaccaria Valentina , Fentaye Amare D. , Kyprianidis Konstantinos G. 
Published: January 2021

Abstract
As a consequence of globalization and advances in digital tools, synchronous or asynchronous distance courses are becoming an integral part of universities’ educational offers. The design of an online course introduces more challenges compared to a traditional on campus course with face to face lectures. This is true especially for engineering subjects where problem or project-based courses may be preferred to stimulate critical thinking and engage the learners with real-life problems. However, realizing this with distance learning implies that a similar study pace should be kept by the learners involved. This may not be easy, since individual pace is often a motivation for choosing a distance course. Student engagement in group projects, collaborations, and the proper design of examination tasks are only some of the challenges in designing a distance course for an engineering program.
A series of web-based courses on measurement techniques, control, and diagnostics were developed and delivered to groups of learners. Each course comprised short modules covering key points of the subject and aimed at getting learners to understand both the fundamental concepts that they do not typically learn or understand in the respective base courses and to build on that knowledge to reach a more advanced cognitive level.
The experience obtained in the courses on what strategies worked better or worse for the learners is presented in this paper. A comparison between the courses provides an interesting outlook on how the learners reacted to slightly different requirements and incentives in each course. The results from the evaluation of the courses are also used as a base for discussion.
The background and availability of the learners is closely linked to how a course should be designed to optimally fit the learning group, without compromising on the achievement of the learning outcomes. This series of courses is a good example of continuous professional development courses in the field of control, diagnostics, and instrumentation (CDI), and brings with it a number of challenges and opportunities for the development of online courses.
Non-Uniform Source Term Model for Film Cooling With the Internal Cross Flow
Authors: Zhang Zhen , Chen Ziyu , Su Xinrong , Yuan Xin 
Published: January 2021

Abstract
The source term model is an effective way to reduce the calculation consumption in predicting film cooling performance. The aim of this work is to develop a new source term model to consider the non-uniform in-hole flows. The internal cross flow that occurs in air-cooled blades and vanes has been shown to distinctly affect the cooling performance. In this work, the in-hole flow mechanism with the presence of the internal cross flow is studied. A topological model that divides in-hole flows into three parts and several regions is put forward. It is shown that, compared with the parallel ones, the perpendicular internal cross flows dominate the cooling performance. What is more, flows within the cooling hole are not affected by the main flow, especially in the region under a certain plane (named the R plane). This feature makes it possible for a source term model to work under various main flow conditions. Based on these understandings, a non-uniform source term model is established. It models and solves the three-dimensional in-hole flows by a two-dimensional transient solver and describes the effect of the internal cross flow as initial conditions using a vortex model. The result of the transient solver is then transformed into the axial velocity distribution at the R plane and is used as the source term. The prediction of the source term model is compared with full CFD under various VR, VRi and β, showing the ability of this model to predict the effect of the internal cross flow with discrepancy increasing with VR. Accurate modeling of the three-dimensional in-hole flows is the key point in this source term model and needs further development.
Comparison of Radiation and Convection-Based Calibration of Fast-Response Heat Flux Sensors
Authors: Huber Konstantin , Rödiger Tim 
Published: January 2021

Abstract
In this study, the static calibration of different heat flux sensors in radiation- and convection-based procedures are compared. First, three heat flux sensors based on different principles: ALTP (based on the Transverse Seebeck Effect), HFM8E (differential-layer device) and a TG-2000 (circular-foil gage) are calibrated in a laser-based radiation setup and compared to the manufacturers calibration. In a second step, all three heat flux sensors are compared with standard temperature-based, robust heat flux measurement techniques (coaxial thermocouple and slug-calorimeter) within a newly built convection-dominated facility based on stagnation-point measurments of an impinging hot air jet. The obtained results show measurement principle depending divergences indicating that a sensitivity transfer between a radiative calibrated sensor used in a mainly convective environment is not always possible and can lead to significant, systematic errors. By comparing the time signal behavior of temperature based heat flux measurement techniques, benefits for direct heat flux measurement techniques are detected.
Innovative Design, Structural Optimization and Additive Manufacturing of New-Generation Turbine Blades
Authors: Amedei Andrea , Meli Enrico , Rindi Andrea , Romani Benedetta , Pinelli Lorenzo , Vanti Federico , Arnone Andrea , Benvenuti Gianluigi , Fabbrini Marco , Morganti Nicolò 
Published: January 2021

Abstract
The need for high performances is pushing the complexity of mechanical design at very high levels, especially for turbomachinery components.
In this field, structural topology optimization methods together with additive manufacturing techniques for high resistant alloys are considered very promising tools, but their potentialities have not been deeply investigated yet for critical rotating components like new-generation turbine blades.
In this framework, this research work proposes a methodology for the design, the optimization and the additive manufacturing of extremely stressed turbomachinery components like turbine blade-rows. The presented procedure pays particular attention to important aspects of the problems as fluid-structure interactions (forced response and flutter phenomena) and fatigue of materials, going beyond the standard structural optimization approaches found in the literature. The new design strategy enables a substantial reduction of the component mass, limiting the maximum stress and improving the vibrational behaviour of the system in terms of eigenfrequencies, modal shapes and fatigue life.
Furthermore, the numerical procedure shows robustness and efficiency, making the proposed methodology a good tool for rapid design and prototyping, and for reducing the design costs and the time-to-market typical of this kind of mechanical elements.
The procedure has been applied to a low-pressure turbine rotor to improve the aeromechanical behavior while keeping the aerodynamic performance. From the original geometry, mode-shapes, forcing functions (due to rotor/stator interactions) and aerodynamic damping have been numerically evaluated and are used as input data for the following topological optimization. Finally, the optimized geometry has been verified in order to confirm the improved aeromechanical design.
After the structural topology optimization, the final geometries provided by the procedure have been then properly rendered to make them suitable for additive manufacturing. Some prototypes of the new optimized turbine blade have been manufactured from aluminum to be tested mechanically and in terms of fatigue.
Experimental Investigations on the Pressure Fluctuations in the Sealing Gap of Dry Gas Seals With Embedded Pressure Sensors
Authors: Luo Jingjing , Brillert Dieter 
Published: January 2021

Abstract
Dry gas lubricated non-contacting mechanical seals (DGS), most commonly found in centrifugal compressors, prevent the process gas flow into the atmosphere. Especially when high speed is combined with high pressure, DGS is the preferred choice over other sealing alternatives. Even though the non-contacting seal is proved reliable; the ultra-thin gas film can still lead to a host of potential problems due to possible contact.
In order to investigate the flow field in the sealing gap and to facilitate the numerical prediction of the seal performance, a dedicated test facility is developed to carry out the measurement of key parameters in the gas film. Gas in the sealing film varies according to the seal inlet pressure, and the thickness of gas film depends on this fluctuated pressure. In this paper, the test facility, measurement methods and the first results of static pressure measurements in the sealing gap of the DGS obtained in the described test facility are presented. An industry DGS with three-dimensional grooves on the surface of the rotating ring, where experimental investigations take place, is used. The static pressure in the gas film is measured, up to 20 bar and 8,100 rpm, by several high frequency ultraminiature pressure transducers embedded into the stationary ring. The experimental results are discussed and compared with the numerical model programmed in MATLAB [1], the characteristic and magnitude of which have a good agreement with the numerical simulations. It suggests the feasibility of measuring pressure profiles of the standard industry DGS under pressurized dynamic operating conditions without altering the key components of the seal and thereby affecting the seal performance.
Life Prediction Modeling of Combined High-Cycle Fatigue and Creep
Authors: Bouchenot Thomas , Patel Kirtan , Gordon Ali P. , Shinde Sachin 
Published: January 2021

Abstract
Industrial gas turbine blades are subjected to high temperatures and an array of mechanical and dynamic loads, making creep and high-cycle fatigue critical aspects of turbine blade design. The combination of creep and high-cycle fatigue produces a synergistic interaction effect whose explicit consequence to turbine life has been the subject of very little research. This interaction remains unaccounted for by current, decoupled life prediction models, which traditionally incorporate such interactions into conservative design safety factors. Improved lifing models capable of capturing these effects are now needed in order to maintain current reliability standards in next-generation operating conditions.
This research identifies the life-limiting aspect of a combined high-cycle fatigue and creep response in conventionally cast Alloy 247 LC, and captures the interaction of the two loads in a novel life prediction model. The proposed model is created from a comprehensive collection of experimental data obtained using an unconventional two-part test method, where test specimens pre-deformed to a prescribed creep strain are fatigue loaded at an elevated temperature and high frequency until failure. A variety of temperatures, creep strains, and fatigue loading conditions are explored to ensure that the resulting model is applicable to the myriad of potential turbine blade operating conditions. Rigorous metallographic assessments accompanying each test are leveraged to create a microstructurally-informed combined life prediction model.
Quality Key Numbers of Gas Turbine Combined Cycles
Authors: Wettstein Hans E. 
Published: January 2021

Abstract
The most relevant quality key numbers for the largest and most efficient Gas Turbine Combined Cycles (GTCC) are not (only) the data published by the original engine manufacturers OEM’s. Additional numbers are here evaluated with educated guesses based on published data of the latest announcements of the “big four OEM’s” [8]. Such data are of interest for potential customers but also for nailing down the current state-of-the-art for all kind of further cycle studies using turbomachinery components and also as a contemporary history record.
Making educated guesses means thermodynamic 1D simulation based on additional assumptions for pressure losses and other cycle data, which have a limited influence on the (unpublished) target quality numbers, such as:
• Mixed turbine inlet temperature Tmix. This is a key value describing the technology level. It can be derived independently of the (unpublished) TCLA value. It is a quality number for the general cooling design and for the secondary air systems.
• Polytropic efficiency of the compressor blading. This number describes the aerodynamic quality of the compressor blading.
• Polytropic efficiency of the turbine blading. It describes the quality level of both the blading aerodynamics and of the open air cooling design.
• Distribution of the exergy losses within the GT and in the bottoming cycle. The exergy losses describe the remaining opportunities for further improvements in the thermodynamic cycle design. But they also indicate its limits.
However already the determination of the Tmix is tricky. It depends on the analysis method and on the fluid data applied. The polytropic efficiency of the turbine blading and the exergy losses will depend both on the used methods and on the Tmix found. Achieving a trustable result therefore requires a transparent and reproducible method. In case of application of the found results for performance prediction of similar cycles the same method has to be applied in order to avoid mistakes.
In this paper real gas data with consideration of dissociation in equilibrium are used, while the polytropic efficiencies are determined with an incremental method based directly on the classic definitions of Stodola [3] and Dzung [4]. Therefore the still most used method using semi-perfect gas properties and corresponding formulas is bypassed.
In order to keep it as simple as possible the evaluation is limited to base load at ISO ambient condition (15°C, 60% relative humidity, sea level). The fuel is limited to pure methane according to the practice in current catalogue data.
The main focus is on the gas turbine with its components. The steam bottoming cycle is captured with its effect on the overall exergy and energy balance of the GTCC, which identifies exhaust and condensation losses.