bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance Comparison of Different Leading Edge Cooling Layouts Considering Inlet Swirl
Authors: Hu Kexin , Zhang Zhen , Su Xinrong , Yuan Xin 
Published: August 2024

Abstract
In modern aero-engine and gas turbine, the interaction between the combustor and the turbine has a significant impact on both aerodynamic and cooling performance of the turbine. Due to the interaction between the combustor and the turbine, non-uniform distributions of temperature and velocity can be observed on the inlet surface of the turbine, which notably affect the performance of turbine blade. The primary research interest of this work is to improve the cooling performance by optimizing the layout of the cooling holes according to the researches on the influence of swirl. First, cooling performance comparison of different inlet swirl is conducted using the measurement based on Pressure-Sensitive-Paint (PSP) technology. The swirl generator with the swirl number 0.778 is used to simulate the non-uniform velocity inlet and the related distance of vane was changed. As the swirl which core has the same circumferential position with the leading edge caused the worst influence to film cooling and made the coverage of film become highly asymmetric, then asymmetric cooling hole layouts, which cooling hole distributions driven by sinusoidal function, were studied by numerical methods and find they can clearly improve the cooling performance on swirl condition. Lastly, based on the experimental results and the analyses, a new layout based on the stagnation line is proposed, which can increase the uniformity of film cooling effectiveness and the performance is verified by PSP experiment. The new layout can increase the area-averaged film cooling effectiveness up to 9.7% under high blowing ratio and reduce the standard deviation of film cooling effectiveness to 24.3% under low blowing ratio. Thus changing the layout of film holes especial the leading edge is an efficient and practical method to improve the cooling performance under swirl condition.
Experimental and Numerical Comparison of Two Turbine Vane Frame Designs
Authors: Krajnc Nicolas , Hafizovic Asim , Wiesinger Lukas , Mangini Francesco , Sterzinger Patrick Zeno , Patinios Marios , Göttlich Emil 
Published: August 2024

Abstract
This paper presents an experimental study supported by numerical simulations of the performance of two turbine vane frames (TVFs) at various purge and TVF inlet swirl conditions representing both on- and off-design operation. The turbine vane frame (TVF) serves as a structural link connecting the last high-pressure turbine stage to the first low-pressure turbine stage, functioning as a vane row for the latter. The two configurations considered share a common fully purged high-pressure turbine stage, followed by distinct TVF and LPT rotor setups. Of the two TVFs considered, TVF1 features a single-splitter, while TVF2 incorporates a twin-splitter architecture.
The experiments took place at Graz University of Technology’s Transonic Test Turbine Facility (TTTF). The steady RANS simulations use 2D inlet boundary conditions derived from measurements and provide additional insights into critical flow phenomena.
The dataset includes purge derivatives with three purge flow rates (PFR) of 0%, 50%, and 200%, the aero design point (ADP) with 100% PFR, and one swirl derivative with positive incidence for each case.
Both configurations exhibit unique flow phenomena, leading to distinct ‘regions of sensitivity’ for each duct design. Due to the positive incidence and low aspect ratio strut design, TVF1 demonstrates a pronounced UPV that affects almost the entire span at the duct exit. Additionally, the UPV is found to be enhanced by the radial pressure gradient imposed by the duct’s second bend.
In contrast, TVF2 experiences a region of low momentum flow at the hub, due to the combination of axial diffusion (as a result of area increase) and high flow turning. This low momentum flow region is manifested as a band of very low axial velocity, spread evenly around the circumference between the airfoil trailing edges and the LP-rotor.
Purge variations exert differing impacts on the investigated geometries, with TVF2 showcasing greater robustness to purge derivatives.
Effects of Inlet Total Pressure Distortion on the Performance of a Two-Stage Transonic Fan
Authors: Qiu Jiahui , Zhao Hongliang , Yang Chen , Du Juan , Zhang Min , Qin Yaolong 
Published: August 2024

Abstract
Improving the understanding of the interaction between multistage fan and an inlet total pressure distortion is benefical to design an advanced compression system and stabilizing measures with strong anti-distortion ability. Full-annulus unsteady simulation is applied in a two stage fan to supplement the physic of distorted flow transfer that is difficult to measure in the experiment. The tip flow fields of Rotor 1 with distorted inflow obtained by unsteady computations agree well with experiment. Total temperature distortion generates as flow passes through the first stage. The results obtained by orbit-method show that the position of the second stage of maximum flow separation locates in where the rotor turns out the lowest total pressure region and turns into the highest total temperature region. The application of inlet distortion distinctly alters the blade loading of Rotor 1, while has negligible effect on Rotor 2 loading, resulting in the blade loading of R1 is greater than that of R2 above 75% span. The process of disturbance generation-development-suppression is captured by unsteady simulations, which is consistent with measurement data. The stall inception finally generates at the tip of Rotor 1, and its circumferential position locates in where rotor turns out of distortion. Distinct from previous studies, the total pressure distortion level, with a large enhancement by the first stage, progresses through the fan with a significantly attenuation by the second stage, and so is the total temperature distortion level.
Investigation on the Flow Mechanism and Dynamic Response Performance of Efficient Fluidic Thrust Vectoring Serpentine Nozzle
Authors: Shi Jingwei , Hui ZhongHao , Zhou Li , Wang Zhanxue 
Published: August 2024

Abstract
High maneuverability, wide speed range, and strong stealth are the key technical requirements for the exhaust system of advanced fighters. The main technical manifestation of high maneuverability and wide speed range is thrust vectoring technology, and the main technical manifestation of strong stealth is the serpentine nozzle. The efficient fluidic thrust vectoring (FTV) serpentine nozzle not only has the above advantages, but also has simpler structure, lighter weight, and quicker vector response. There are complex pressure gradients and strong swirl characteristics inside the serpentine nozzle, such that efficient FTV design of the serpentine nozzle faces greater challenges than conventional nozzles. Therefore, it is important to conduct in-depth study on the efficient FTV serpentine nozzle. This paper conducted a numerical investigation on the flow mechanism and dynamic response performance of an efficient FTV serpentine nozzle. Results show that the depth of the secondary injection can be effectively increased by setting an additional auxiliary injection in front of the secondary injection, which results in the increase of the angle of the induced shock wave and a more obvious deflection of the mainstream. For the high pressure ratio, the time of thrust vectoring formation of the efficient FTV serpentine nozzle is about 10ms, in which the sudden rise of the thrust vectoring angle occurs in 1.4ms. After about 12ms, the flow and thrust vectoring angle tend to be stable. The recovery time of the efficient FTV serpentine nozzle does not exceed 10ms, which is about half the time of the thrust vectoring formation. Generally speaking, the dynamic response of the efficient FTV serpentine nozzle can be completed in 20ms, which is faster than that of the conventional mechanical thrust vectoring nozzles, and its thrust vectoring response rate is about 20–50 times that of mechanical ones.
Investigation of the Heat Transfer Performance in a Double-Wall Cooling Configuration Under the Effect of Wall Curvature at Rotating Conditions
Authors: Wang Xianyu , You Ruquan , Li Haiwang 
Published: August 2024

Abstract
This paper presents an experimental investigation of a double-wall model derived from simplified real turbine blades. The study examines the influence of three distinct wall curvatures and rotation on the internal flow patterns and heat transfer characteristics within the double-wall cooling configuration. It elucidates the mechanisms by which wall curvature and rotation effects impact the performance of the double-wall cooling unit. Conducting flow characteristic experiments on three different wall curvature specimens (flat, convex curvature, concave curvature), experiments were carried out under stationary conditions and at different rotational speeds (30rpm, 60rpm, and 120rpm) for each respective condition. The Particle Image Velocimetry (PIV) experimental results reveal that the flow within the cavity of the double-layer wall cooling configuration is characterized by a complex, three-dimensional, multi-vortex flow, primarily dominated by impingement/effusion dynamics. Wall curvature modifies internal flow characteristics by altering the geometry of the impacted surface and the relative shock distance. Notably, this curvature has a substantial impact on mainstream flow rates and key vortex structures. Additionally, rotation induces centrifugal and Coriolis forces, which enhance the heat transfer capabilities of the double-wall cooling mechanism. The flow can reflect heat transfer, and the analysis of the results from the flow characteristic experiments reveals that, compared to the square double-wall structure, the double-wall structure with convex curvature overall exhibits better heat transfer efficiency, while the one with concave curvature shows poorer heat transfer performance. This is primarily due to the influence of wall curvature on the flow in the main flow region inside the cavity, as well as on vortex structures that play a crucial role in heat exchange. At lower rotational speeds, rotation enhances the heat transfer efficiency of the double-wall cooling structure.
Fatigue Crack Growth of Turbine Disc Part Considering Effect of Shotpeen Nonlinear Stress Gradients Using Finite Element Based and Numerical Methods
Authors: Ertekin Şevket , Yılmaz Adem 
Published: August 2024

Abstract
Crack growth in mechanical components is affected by the residual stress gradient around the crack zone. Shot peen is one of the cold working processes used to generate compressive residual stress layer on gas turbine engine parts. The aerospace industry frequently uses shot peening to increase the fatigue life of mechanical components. In this study, mechanical properties of disc part made of nickel-base super alloy material are modified by applying shot peen residual stress parameters. Three-dimensional residual stress modification is transformed to finite element model of the uncracked area. Then, surface semi-elliptical crack introduced in the finite element model on the maximum principal stress orientation on the surface. One of the most recent, adaptive remeshing capabilities are used during simulations by using Ansys SMART. Crack front element division and incremental crack advance in each step of FEM are fine-tuned by different parameter sets. After each simulation step, new crack front is calculated, and finite element model is updated consequently. Then, crack growth is calculated using mixed-mode maximum circumferential stress criterion until the failure. Similar procedure is performed to create a numerical weight function solution by employing empirical formulas. Shot peen effect is converted into the residual stress intensity factor by using weight function method. Yau’s weight function formulation was used to calculate residual stress intensity values with Newman-Raju surface crack solution. This residual stress intensity profile mostly affects the stress distribution in a compressive stress manner causing lower crack growth rates. This yields a variation on SIF around the crack tip zone. At that point, fatigue crack growth is also calculated by numerical solutions. Results are compared with FEM based mixed-mode crack growth and differences in results are highlighted. Applicability of FEM based crack growth method on shot peen application is investigated. The role of the shot peen operations and consequence of surface residual stress during crack growth is emphasized.
Model Order Determination for Modal Parameter Estimation: Application to a Composite Fan Stage
Authors: Jorajuria Corentin , Gibert Claude , Esteves Cécile , Thouverez Fabrice 
Published: August 2024

Abstract
Experimental methods are necessary to quantify structural damping. Among these methods, modal testing of bladed disks are of particular interest because it provides an efficient experimental characterization of these structures which are critical parts of aeronautic turbojet engines. This work presents techniques to determine the optimal order of subspace state-space identification methods for modal parameter estimation of a realistic fan stage. Indeed, the order of the identification model is unknown during modal analysis requiring techniques to determine which model order should be used for parameter estimation. To investigate these techniques, several methods to estimate the optimal model order are reviewed. A specific focus is proposed on the determination of model order through statistical tests as these techniques have the benefits of providing indicators along with a threshold built over hypothesis testing and a probability of rejection. In order to further analyze model order determination techniques, some of these techniques are evaluated by means of a numerical model of a realistic fan stage, hence making possible to assess the performances of estimation methods close to experimental conditions. In particular, estimation in a context of high modal density as well as model order determination through “M-test” are addressed using this model. After assessing the implemented estimation method over the numerical model, this method is applied over experimental data obtained by performing modal tests over a full-scale composite rotating fan in vacuum condition.
Fuel Property Impact on Lean Blow Out for Sustainable Aviation Fuels in Gas Turbine Combustors
Authors: Dasgupta Debolina , Som Sibendu 
Published: August 2024

Abstract
Sustainable Aviation Fuels (SAF) offer a solution for lowering the carbon emissions produced by the aviation sector. However, these fuels have different properties than traditional jet fuels. In order to understand the effects of changes in fuel properties on the behavior of flames, Large-Eddy Simulations of the Referee Rig are performed under stable conditions. The fuel used in these simulations is the average jet fuel, A-2, which serves as the reference fuel. Perturbations are made to the fuel’s density, viscosity, and heat of combustion to determine the impact of each on the behavior of the flame. The combined effects of two or three properties are also analyzed. Changes in density and kinematic viscosity have an impact on secondary atomization and vaporization, which in turn modify flame symmetry and droplet sizes near the flame anchoring region. An increase in heat of combustion leads to an increase in heat release and temperature within the combustor. Overall, a reduction in density, kinematic viscosity, and an increase in heat of combustion increase flame resilience, which results in a reduction in the LBO GER.
The Axial-Throughflow Influence on the Taylor Vortices In Taylor-Couette-Poiseuille System
Authors: Li Siyi , Du Qiang , Xie Yaguang , Liu Guang , Lian Zengyan , Luo Yifu , Xie Lei 
Published: August 2024

Abstract
Integrating axial throughflow into the Taylor-Couette systems enhances the complexity of the Taylor-vortices structure, which is a critical configuration positioned between the high-pressure and low-pressure shafts in aeroengines where there exists a rotational speed difference, referred to as Taylor-Couette-Poiseuille (T-C-P) system. The axial throughflow and temperature difference influence the characteristics of cooling airflow’s resistance and heat transfer, and consequently affects the rotor-stator’s axial/radial clearance, much further, hence, affects the performance and efficiency of the aero-engine. To investigate the impact of axial throughflow on the T-C-P system, we conducted direct numerical simulations (DNS) to analyze the axial-throughflow behavior within the T-C-P system. As the magnitude of axial throughflow increases, the initially uniform distribution of Taylor vortices becomes discontinuous and fragmented. With further enhanced throughflow, the entire Taylor vortices are propelled to downstream with an averaging axial velocity. Eventually, the Taylor vortices are expelled and fully disappeared as the axial throughflow becomes sufficiently large, resembling the flow characteristics of a Poiseuille system. The flow field is predominantly influenced by the rotating inner cylinder at the relatively lower magnitude of axial throughflow’s velocity. As the axial Reynolds number surpasses 100, the system transitions to being dominated by the axial throughflow. Therefore, this evolution highlights the profound influence of axial throughflow on the transition of Taylor vortices and lays the groundwork for subsequent research on the flow control and heat transfer in the T-C-P system.
A Holistic Conceptual Synthesis and Analysis of Fuel Cell System Architectures Using 1D Coupled Thermofluid and Electrochemical Lumped Parameter System Simulation
Authors: Goldenberg Vlad , Conser Ben , Joly Clement , Moroz Leonid 
Published: August 2024

Abstract
In this work, several fuel cell system architectures are described and analyzed. The architecture variability includes uncoupled/coupled cooling and aspirant systems, the inclusion or exclusion of an energy recovery turboexpander on the exhaust, and, for those that include a turboexpander, the inclusion or exclusion of thermal recuperation.
It is recognized a-priori that certain architectures will have specific advantages over others. It is also recognized that there are several performance metrics that may be sought. They include power system efficiency, gravimetric power density, volumetric power density, and specific cost per capacity. The analyses carried out in this work lead to a novel way to minimize the cost of a fuel cell power system. Specifically, knowing that the fuel cell proper represents the highest cost component of a fuel cell based power system, it is shown that one can optimize for maximum “bang for the buck” in a surrogate fashion in a holistic system analysis. The key to being able to achieve this is having a reliable electrochemical analysis model of a cell coupled with an overall system simulation model. Thus, for a variation of parameters, it can be predicted how relative fuel cell stack specific power density changes with parameter variation. The outcome of this paper is a documentation of several integrated fuel cell system architectures with a parametric analysis and resulting performance metrics of each system when independently optimized for efficiency, power density, and fuel cell specific power capacity, showing an improvement of about 15% over a simple baseline.
Implementation of Artificial Intelligence for Aircraft Engine Health Monitoring and Prognostics
Authors: Aditya Aditya , Nikolaidis Theoklis , Manuel Arias Chao , Togni Simone 
Published: August 2024

Abstract
Improving the availability and reliability of aircraft engines is paramount in managing the aircraft fleet’s efficiency. While previous efforts have primarily focused on condition-based monitoring and Remaining Useful Life (RUL) prediction based on physics-based models, this paper introduces a novel approach to Engine Health Monitoring (EHM) using deep learning models. In particular, this work leverages critical engine parameters such as surge margin and exhaust gas temperature margin for interpretable EHM and prognostics. We present three deep learning models, namely, the Multi-Layer Perceptron (MLP), Convolutional Neural Network (CNN), and Long-Short Term Memory (LSTM), optimized for these tasks. The models were trained using synthetic data of 100 CFM 56 5B Turbofan engine-inspired models, simulating various flight cycles at steady-state cruise conditions using TURBOMATCH software (Cranfield University in-house aircraft engine performance simulation tool). The degradation in each engine was based on mass flow capacity and efficiency variation in the fan, compressor, and turbine, which is the effect of fouling, erosion, corrosion, etc. Unlike the existing datasets, this study deployed full factorial degradation of engine components and a wide range of degradation scenarios.
Results demonstrate the competitiveness of the proposed models, as evidenced by low Root Mean Square Error (RMSE) values. The CNN model performs well in health monitoring, achieving an RMSE of 0.0148 health margin prediction. In contrast, the LSTM model proves most effective in predicting Remaining Useful Life, with an RMSE of 53.64 flight cycles. In conclusion, deep CNN and LSTM models showed a promising method for accurate engine condition monitoring and RUL predictions.
3D Temperature Evaluation of the Vane Based on Fluid-Network Method
Authors: Zhang Siyuan , Li Xueying , Ren Jing 
Published: August 2024

Abstract
With the continuous increase of inlet temperature of the gas turbine, the design of turbine cooling structures is facing great challenge. The fluid-network method is widely used in the initial stage of the turbine design due to its advantages of high speed and precision. However, this method is difficult to achieve 3D temperature evaluation of turbines and it fails to meet the demands of engineering specifications.
This research develops a 3D evaluation method for the vane based on the fluid-network method. The method translates cooling structures into topological elements, which directly solves the momentum and energy equations. Correlations summarized from experimental data was combined to obtain the pressure, flow rate, temperature, and heat transfer coefficient distribution of the cooling elements quickly and accurately. This research compared the calculation results of the 3D evaluation method and Computational Fluid Dynamics (CFD) method with design prediction. The results show that the errors of the two methods are at the same level, and the 3D evaluation method has higher computational efficiency. It is proved that the 3D evaluation method can quickly predict the 3D temperature distribution and cooling efficiency of different cooling structure layouts in the initial stage of turbine design. Therefore, this research lays a foundation of the optimizing of cooling structures, which could support the design of the next generation high-performance turbine.