bluuebunny/crossref_metadata_2025_split huggingface dataset:
Data-Driven Generative Model Aimed to Create Synthetic Data for the Long-Term Forecast of Gas Turbine Operation
Authors: Losi Enzo , Manservigi Lucrezia , Spina Pier Ruggero , Venturini Mauro 
Published: August 2024

Abstract
The prediction of gas turbine (GT) future health state plays a strategic role in the current energy sector. However, in the case of limited historical data, e.g., a new installation, training an accurate prognostic model may be challenging.
To this aim, this paper develops a Generative Adversarial Network (GAN) model aimed to generate synthetic data that can be used for data augmentation. The GAN model includes two neural networks, i.e., a generator and a discriminator. The generator aims to generate synthetic data that mimic the pattern of real data. The discriminator is a binary classification network. During the training process, the generator is optimized to fool the discriminator in distinguishing between real and synthetic data.
The real data employed in this paper were taken from the literature and gathered from three GTs. Data refer to two quantities, i.e., corrected power output and compressor efficiency, which are tracked during several years.
Three different analyses are presented to validate the reliability of the synthetic dataset. First, a visual comparison of real and synthetic data is performed. Then, two metrics are employed to quantitively evaluate the similarity between real and synthetic data distributions. Finally, a digital twin (DT) model is trained by only using synthetic data and then it is employed for the prediction of real data.
The results prove the high reliability of the synthetic data, which can be thus exploited to train a DT model suitable for prognostic purposes. In fact, the prediction error of the DT model on the real data is lower than 2.5% even in the case of long-term prediction.
Numerical Investigation of the Heat Transfer and Discharge Coefficient of the Narrow Double Wall Cooling
Authors: Xu Qingzong , Du Qiang , Wang Pei , Xu Guangyao , Liu Haoyang , Li Hongye 
Published: August 2024

Abstract
A numerical investigation was conducted to explore the heat transfer and discharge characteristics of a narrow double wall cooling configuration. The narrow double wall cooling configuration comprises a row of impingement holes and a row of film holes. Two impingement distances, Z/D = 1 and Z/D = 2, were studied, along with six impingement Reynolds numbers ranging from 5000 to 30000. In addition, the layout of the impingement hole and the film hole was also investigated. The study employed the RANS method with the SST k-ω turbulence model. In addition to investigating heat transfer on the impingement target wall, the heat transfer on the side wall and the impingement wall was also examined to assess heat flux distribution within the system. The results indicate that impingement distance rarely affects heat transfer on the target wall in the context of narrow double wall cooling. When the impingement distance is increased from Z/D = 1 to Z/D = 2, there is a noticeable rise in heat transfer on the side wall and the impingement wall, leading to a higher total heat flux within the impingement channel. Results indicate that reversing the positions of the impingement and film holes has negligible effect on the target wall heat transfer. Furthermore, the overall discharge coefficient, considering both the impingement hole and the film hole, remains comparable for the three schemes studied. The reverse impingement film cooling decreases the discharge coefficient of the film hole due to the large flow separation at the hole inlet.
Impact of the Blade Fillet Radius on the Aerodynamic Performance of an Unshrouded Centrifugal Compressor
Authors: Hoang Duc Huy Marco , Châtel Arnaud , Verstraete Tom 
Published: August 2024

Abstract
Fillets are often neglected in the flow analysis of centrifugal compressors due to the assumption of having little influence on the flow field and the difficulties related to the grid generation. Existing studies have shown an impact on efficiency, pressure ratio and choke margin by including fillets in the flow simulation. The goal of the present work is to investigate the impact of the fillet radius on the aerodynamic performance in an unshrouded centrifugal compressor. A parametric study on the blade hub fillet radius is conducted using the “RadiVer” test geometry and steady state CFD analysis. By using common methods for grid generation of turbomachinery blade passages, which are stacking the surface grids for each blade section, 3D features, such as fillets, cannot be meshed properly. Therefore, a new topology for 3D multi-block structured grid generation of radial impeller blades including hub fillets is proposed. Transfinite interpolation is used to create the initial grid and elliptic smoothing is applied afterwards for removing grid folding and improving grid quality.
From the results of the flow simulations an improvement of the compressor performance with larger fillet radius is observed. Modifying the fillet radius mainly influences the flow downstream of the blade trailing edge. Even though the impeller efficiency decreases as the fillet size gets larger, due to the increased tip leakage flow, the diffuser performance improves, leading to an overall increase of the compressor efficiency. The improvement of the diffuser performance is attributed to the lower static pressure at the trailing edge as the fillet radius increases. The lower static pressure allows the flow to get sucked out from the backwards facing step and to distribute over the whole span of the diffuser. On the one hand, this leads to increased mixing losses. On the other hand, the entrapment of the flow at the backwards facing step can be avoided in that way, which overall leads to a reduced total pressure loss in the diffuser.
Enhanced Adiabatic Film Cooling Effectiveness by Varying Compound Angle
Authors: Pyo Yeongmin , Broumand Mohsen , Son Juchan , Richer Patrick , Jodoin Bertrand , Hong Zekai 
Published: August 2024

Abstract
Effusion cooling is the state-of-the-art cooling technology for gas turbines. However, the compound angle of effusion cooling holes is commonly set as a fixed value in prior studies. In particular, the compound angle is mostly set to zero in practice by assuming that highly directional miniature effusion cooling jets are aligned with the main flow. A recent study from our group has examined the directional effects of effusion cooling on adiabatic film cooling effectiveness (AFE) subjecting to a swirling main flow. It was found that a large compound angle initially facilitates a quick build-up of cooling film and the optimal compound angle reduced to smaller values downstream where the cooling film is further developed. The current study exploits the recent findings in the directional effects of effusion cooling by proposing novel effusion cooling designs with varying compound angles of cooling holes which are optimized for improving AFE along the main flow direction. In the present study, AFE was experimentally determined using Pressure Sensitive Paint (PSP) through invoking the heat/mass transfer analogy. A new effusion cooling design was evaluated by setting the compound angles of effusion cooling holes to three discrete values of 90, 60, and 30 degrees at three successive regions along the direction of the main flow. 2D AFE maps resulting from the proposed design were compared with those of conventional effusion cooling designs with fixed compound angles under identical conditions. It was found that the new effusion cooling design featuring varying compound angles produces a more uniform cooling film coverage and a small enhancement to AFE comparing to the conventional effusion cooling designs.
Few Common Observations From a Vibration Test Data
Authors: Kumar Avinash , Iyappan Praveen , Kumbham Krishna Mohan 
Published: August 2024

Abstract
Typical vibration test data, especially from transient vibration tests, contains several observations with reference to test data measurement quality and physics of response. In this paper, few common observations are highlighted. These observations are obtained from both shock type test and steady state vibration test. First observation — In case of shock type loading, accelerometer data is usually found to have multiple local drifts in the signal. It is understood that presence of these multiple drifts doesn’t necessarily mean that the data is corrupted, but data can still be very reliable if drifts are removed. Second observation — In a system with significant rubs during dynamic test, it is commonly observed that vibration response contains frequencies of multiple orders of fundamental excitation frequency. Vibration at multiple orders is localized to the rubbing zone and dies away as we move far from the rubbing zone. Third observation — During shock testing, accelerometers contain large acceleration at higher frequencies, while strain gauge data doesn’t usually show significant strain at higher frequencies. Higher acceleration at higher frequencies leads to smaller displacement which then leads to lower loading into the system. Fourth observation — In case of base excitation tests, in which input signal is multi-tonal, high frequency tones gets attenuated through the compliant mounting and doesn’t show as an output on mounted device. These observations are described in detail in this paper.
Effect of the Upstream Shroud Purge Flow on the Cooling Performances of Turbine Blade Tip
Authors: Xue Zhenzhen , Li Haiwang , Tao Zhi , Zhou Zhiyu , Meng Long , Xie Gang 
Published: August 2024

Abstract
Researches on the turbine blade tip cooling mainly focus on the arrangement of the film holes in the blade tip and the shroud. In fact, the purge flow located upstream of the turbine blade leading edge also influences the cooling of the turbine blade tip region. In present study, the effects of purge flow on the cooling performance and flow field around the blade tip were investigated by numerical simulation using 3-D steady RANS approach with the k-ω turbulence model. The first-stage high-pressure turbine blade of GE-E3 was employed in present work. Three parameters of the purge flow were investigated, which were the inlet angle of the purge flow (30°, 60° and 90°), the relative position between the leading edge of the blade and the purge flow (10 %, 25 % and 40 % of the vane-blade distance), and the mass flow rate of the coolant (1 %, 1.5 % and 2 % of the main flow rate). The results indicate that the presence of the shroud purge flow has a significant influence on the film cooling of blade tip. As the inlet angle increases, higher vertical velocity reduces the lift-off of cooling jet, leading to worse tip cooling performance. However as the distance increases, the cooling performance improves. As the coolant flow rate increases, the cooling performance gets better.
Possibilities of Applying Machine Learning Techniques for Probabilistic Analysis in a Turbine Blade-Disk Interface
Authors: Emmrich Elmira , Islam Md Tarekul , Voigt Matthias , Bruder Lukas , von Lautz Julian , Mailach Ronald 
Published: August 2024

Abstract
The design of the blade-disk interface in a jet engine is crucial, as the stresses on both disk and blade directly affect the engine’s service life and potentially lead to catastrophic failure. In particular, any variation in design parameters can have a significant impact on the life of the components. While finite element (FE) analysis is commonly used to analyze the effects of each variation on the geometry separately, surrogate models can be a much more efficient alternative to explore these effects and thus the design space, as long as they can describe the system behavior well.
This paper addresses the challenge of surrogate modeling a high-dimensional parameterized FE model of a turbine blade-disk interface using deep neural networks (DNNs) to describe the system behavior. Sampling methods as a part of Monte Carlo simulation (MCS), are used for training to evaluate the efficiency of using DNNs.
In applications such as FE analysis, where interactions between neighboring nodes are essential, DNNs are advantageous due to their ability to account for these interactions and to process a large amount of data simultaneously and for all nodes in an FE model, so that there is only one DNN model for the entire FE model. They can adapt to different mesh topologies, eliminating the need for topologically identical positions, unlike conventional approaches such as node-based least squares. This advantage of DNNs is demonstrated in this work by a comparative analysis of geometry variation due to manufacturing tolerances and its impact on stress values using an in-house probabilistic tool MetamodelGUI. With this tool, the FE results of an MCS can be visualized in a much easier and faster way and the components can be preliminary designed using surrogate models. In addition, the ability of using DNNs to perform sensitivity analyses is evaluated. Furthermore, the robustness of DNN models for describing the system behavior is discussed, as well as the feasibility of using this method for robust optimization and failure probability estimation.
Effusion Cooling Characteristics of Effusion-Cooled Combustor Liners With Different Hole Configurations Under Swirl Impact
Authors: Xiang Lu , Yuliang Jia , Yongbin Ji , Bing Ge , Shusheng Zang 
Published: August 2024

Abstract
The conjugate cooling characteristics of effusion-cooled n-shaped holes, were compared with the combustor widely used cooling air pressure drop (ΔPcool) ranging from 0.08% to 1.90%. All plates were covered by a thermal barrier coating. The cooling effectiveness distribution correlates closely to the swirl impact. In specific, there appear two low-effectiveness regions due to the swirl impact. The area of the regions for the cylindrical holes account for 37.52% to 13.77% of the plate as the cooling air pressure drop increases, and the fan-shaped and laidback fan-shaped holes have gradually smaller area. The lowest effectiveness for the cylindrical holes is 27.5% to 14.3% lower than the average, and for the fan-shaped and laidback fan-shaped holes the value increases, meaning greater disuniformity of cooling effectiveness. In terms of the cooling performance, the laidback fan-shaped holes are the best, 0.05 higher than the worst cylindrical holes in cooling effectiveness. The points that are lowest in cooling effectiveness, migrate along the center line of the regions forward as the pressure drop increases and downstream as the hole outlet expands since the increasing of outlet velocity of cooling holes is significant for the resistance of swirl impact.
An Aerodynamic Investigation of a High-Pressure Turbine Using Rotor Casing Static Pressure Measurements at Engine Representative Conditions With Different Tip Designs, Tip Gaps and Inlet Temperature Profiles
Authors: Singh Deepanshu , Beard Paul F. , Cardwell David , Staelens Vianney , Bahulekar Pratik , Stokes Mark , Bather Simon , Chana Kam S. 
Published: August 2024

Abstract
A rotating High-Pressure (HP) turbine, in modern aircraft engines, is subjected to high cyclic thermal and mechanical loads. Shroudless turbines experience high heat loads on the rotor tip and casing, which makes them one of the life-limiting components for an engine. If the rotor tip starts to erode, then the tip clearance increases which increases the over-tip leakage flow, resulting in reduced stage efficiency and ultimately, the engine lifetime. Since the 1970s, extensive research has been undertaken to understand the over-tip leakage flow, and develop mitigation strategies such as novel tip designs, to minimize the losses and heat load. However, the majority of the present findings are based on linear cascade or low-speed rotational studies, due to the high cost of the experiments and difficulty in instrumentation at engine conditions. Recent studies (mostly numerical) have shown the importance of testing at engine representative conditions, specifically targeting the transonic tip flow in a high-speed rotational environment, which is essential for an accurate understanding.
The Oxford Turbine Research Facility (OTRF) is a highspeed rotating transient test facility that allows unsteady aerodynamics and heat transfer measurements, at engine representative conditions. This paper presents an experimental investigation, of the HP turbine rotor casing aerodynamics, performed in the OTRF. Steady and unsteady casing static pressure measurements were acquired, using pneumatic lines and high-frequency response (∼100 kHz) Kulite pressure transducers respectively. The single-stage HP turbine consisted of cooled vanes (featuring film and trailing edge slot cooling), and uncooled rotor blades. Three different tip designs (two squealers and one flat) were tested, at two tip gaps, and with two inlet temperature profiles that included a spatially uniform total temperature profile and an engine representative HP turbine inlet total temperature profile. In parallel, a numerical investigation of the experimental test cases is presented using unsteady Computational Fluid Dynamics (CFD) predictions. The experimental results from this study provide a unique dataset to validate numerical models.
Advancing Airfoil Design: A Physics-Inspired Neural Network Model
Authors: Unlusoy Can , Maier Bill , Al Handawi Khalil , Varghese Mathew Tittu , Srinivasan Ravichandra , Salz Mathieu , Kokkolaras Michael 
Published: August 2024

Abstract
Turbomachines are an integral part of the energy and industrial landscapes, and improvements to their efficiency benefit the environment, profitability of operation, and in turn, society at large. Therefore, the application of advanced methods for rapid design and development of high-performance turbomachinery components is of significant interest. In the past decade, the use of optimization methods has made inroads in improving turbomachinery aerodynamics. Recent advances in machine learning (ML) methods have the potential to augment design systems by providing the ability to explore larger design spaces and generate high-quality initial designs. Physics Informed Neural Networks (PINNs), based on the Navier-Stokes equations, are used to incorporate physical laws into the design process. This approach leverages the power of deep learning while ensuring that the designs conform to fundamental principles of fluid dynamics. The use of Physics Informed Neural Networks (PINNs) not only accelerates the design process by reducing the need for extensive simulations but also improves the accuracy of the designs by ensuring physical consistency as opposed to designs made using Generative Artificial Intelligence (AI) models. However, combining PINNs with Generative AI for airfoil optimization could provide a fruitful avenue in improving compressor blade designs.
Heat Transfer Enhancement for Gas Turbine Blade Internal Cooling With Lattice Structured Rib
Authors: Kim Sangmin , Park Yong Gap , Yoon Sang Youl , Ha Man Yeong , Min June Kee 
Published: August 2024

Abstract
A higher turbine inlet temperature is crucial for enhancing efficiency in gas turbines. However, this increase can reduce the lifetime of turbine blades due to thermal deformation in the solid material. To address this challenge, this study numerically explores the use of lattice-structured ribs within the internal cooling channels of gas turbine blades to improve heat transfer performance. Conjugate heat transfer analysis evaluates the effectiveness of these ribs. The methodology’s accuracy was affirmed by comparing the results with those of a channel featuring fully-filled ribs under thermal performance factor tests. A constant temperature boundary condition was applied to the channel’s bottom wall in the middle section. The k-ω and SST turbulence models were utilized for their precise prediction of flow separation near wall regions. The results indicate that the flow through the lattice structure mixes with bypass flow downstream, significantly enhancing heat transfer compared to the fully-filled rib model. This enhancement is attributed to the combined effects of flow mixing and increased surface area.
Scaling Heat Transfer and Pressure Losses of Novel Additively Manufactured Rib Designs
Authors: Corbett Thomas M. , Thole Karen A. 
Published: August 2024

Abstract
Rib turbulators are a key cooling feature that enable increased heat transfer on the interior of gas turbine components. As metal additive manufacturing becomes available for developing turbine parts, it is becoming increasingly important to understand how the surface roughness intrinsic to this manufacturing method impacts the performance of rib turbulators. To explore what impact roughness has on rib turbulator performance, several relevant scale test coupons were manufactured on two different additive machines out of IN718. Additionally, several coupons were built at large scales to effectively reduce the relative roughness size impacts and determine scale effects. A range of different wavy broken rib designs, varying both rib wavelength and orientation within a channel were evaluated. Coupon geometry and surface roughness were characterized using both computed tomography scans and optical profilometry. Variations between the print methods were found to have limited impact on the surface roughness, but significant impact on the accuracy to meet the design intent with rib heights varying by 30%. Following characterization, coupons were flow tested and it was found that the ribs that more regularly disturbed the flow as a function of their geometry most significantly enhanced heat transfer and pressure drop. The performance index of the broken wavy ribs was similar to other advanced rib designs, such as broken or V shaped ribs, but augmentations to heat transfer and pressure drop were generally lower. The rib performance was compared as a function of relative roughness, and it was found that increases in relative roughness resulted in increased friction factor and heat transfer, especially at higher Reynolds numbers.