bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Dilution and Effusion Flows in Generating Variable Inlet Profiles for a High-Pressure Turbine
Authors: Schaeffer Chad B. , Barringer Michael D. , Lynch Stephen P. , Thole Karen A. 
Published: August 2024

Abstract
The elevated flow temperatures and pressures exiting gas turbine combustors affect the efficiency and durability of the high-pressure turbine stage. Understanding the effects that result from the upstream dilution and effusion flow interaction in creating the combustor exit profiles are important to advancing gas turbines. Understanding how common combustor features, such as dilution jets and effusion cooling, interact based on computational predictions guided the design of a non-reacting profile simulator capable of producing a wide range of non-uniform temperature profiles representative of those entering high-pressure turbines. The mechanical design of a new simulator device, which will be experimentally tested in the future, is presented in this paper along with computational predictions of flow and thermal fields. The simulator was designed for modular installation into the Steady Thermal Aero Research Turbine (START), which is a continuous-duration, steady-state turbine facility that houses a single-stage test turbine. Features of the simulator included interchangeable liner panels with multiple rows of dilution jets and wall effusion cooling to study various hole diameters and patterns. The dilution jets generate elevated turbulence intensities and tailor the temperature profiles in the radial and circumferential directions. The air mass flow distribution and source flow temperatures are independently controlled. To aid in the simulator design, computational fluid dynamics (CFD) simulations using Reynolds-averaged Navier Stokes modeling were conducted with a two-level Design of Experiments (DOE) approach to determine a number of engine-representative target profiles with temperature shapes that are mid-radius peaked, outer-diameter peaked, inner-diameter peaked, and uniform. A sensitivity analysis of the CFD DOE results determined which factors significantly affected the profile shape so that the target profiles could be produced. The analysis indicated the main contributor to the temperature profile shape at near-wall vane radial span locations of 0–15% and 85–100% was the injection temperature of the effusion flow. The main contributor at radial span locations of 15–40% and 60–85% was the injection temperature of the third-row dilution jets, and at the mid-radius location of 40–60% vane radial span, the main contributor was the diameter of the first-row dilution holes.
Teaching Aero-Engine Performance: From Analytics to Hands-on Exercises Using Gas Turbine Performance Software
Authors: Jeschke Peter , Koschel Wolfgang , Klumpp Christian , Weintraub Daniel 
Published: August 2024

Abstract
In this paper, we present an approach for teaching turbojet engine performance that combines mathematical analysis with the use of gas turbine performance software to provide students with a comprehensive and in-depth understanding of engine performance and how it is affected by design parameter choices.
In the first part, we present the derivation of a universally valid analytical model for turbojet engine cycle design, which is the basis of the aircraft propulsion courses at RWTH Aachen University. The analytical model allows for the calculation of specific thrust as well as thermal and propulsive efficiencies as a function of pressure ratios and burner exit temperature. These are all expressed as differentiable functions. Their mathematical extremes form a basis for examining the intricate relationships in turbojet engine design.
In the second part, we move from theory to practice. We utilize the GasTurb software for gas turbine performance analysis, computing turbojet engine cycles for a wide range of cycle design parameters, including pressure ratios and burner exit temperatures. The analytically derived trends are validated and errors introduced by simplifications are assessed. Differences between the analytical approach and software-based performance simulations of real engines, like temperature-dependent gas properties and secondary air systems, are emphasized and discussed, thus providing a bridge to real-world applications.
In summary, this paper describes a two-step approach to teaching turbojet engine design using analytics and gas turbine performance software. Each approach alone can be used to enrich and extend existing engine performance courses. Combining the approaches has significant benefits, improving understanding and inspiring students to pursue further research in the field of jet engines.
Temperature Field Measurements in Swirl Spray Flames Using Two-Line Planar Laser Induced Fluorescence Thermometry
Authors: Tao Chao , Zhang Chi , An Qiang , Xue Xin 
Published: August 2024

Abstract
This paper investigates the temperature fields in a centrally staged swirl spray combustor using two-line OH planar laser induced fluorescence (PLIF) thermometry at elevated inlet pressures and temperatures up to 0.62 MPa and 650 K. The pilot and main stages of the combustor were supplied with RP-3 kerosene. OH radicals were excited using the Q1(5) and Q1(14) transitions within the A2Σ←X2Π (1, 0) band. Two laser excitation systems were operated simultaneously, where the two beams were spatially combined and separated by a small interval in time. The PLIF signals excited at the two wavelengths were captured by two identical sets of imaging system. The calibration coefficient needed for quantitative conversion from fluorescence ratio to temperature was determined based on results from independent coherent anti-Stokes Raman scattering (CARS) measurements. To enhance the quality of instantaneous temperature fields, a joint threshold mask was developed to remove the noise and weak signals in the raw PLIF images. The high temperature zones in the temperature field were then obtained. In both instantaneous and mean temperature fields, the pilot and main stage flames were identified. In addition, the radial position of the pilot flame showed marked variations at a nominally fixed condition. By extracting the radial profiles, a consistency between the peaks of PLIF intensity and temperature was found, suggesting that PLIF images could be a qualitative substitute for the high temperature zones in the temperature fields of these complex swirl spray flames. This study demonstrates the feasibility of temperature field measurements using two-line OH PLIF in aero-engine model combustors.
Numerical Analysis of Jet Impingement Heat Transfer for Gas Turbine Rotor Blades
Authors: Pagnoni Filippo , Archambaud Damien , Gonzalez-Martino Ignacio , Bonnal Benoît 
Published: August 2024

Abstract
Jet impingement is widely adopted for turbine blade cooling due to the higher heat transfer rate compared to conventional forced convection solutions. Although RANS turbulence modeling is suitable for industrial scale applications, it lacks of accuracy when dealing with jet impingement heat transfer. The present study aims at comparing the aerodynamics and heat transfer of a leading edge cooling cavity for rotating turbine blade applications. The cooling cavity consists of a single array of jets impinging on a leading edge channel provided with three arrays of cooling holes. Different CFD approaches are proposed: RANS/URANS simulations and high-fidelity VLES simulations based on Lattice Boltzmann Methods (LBM). In all cases, commercial CFD solvers are used: ANSYS Fluent and SIMULIA PowerFLOW®, respectively. Despite similar averaged simulation results, substantial local differences emerge when comparing the different models against each other. With the LBM approach, the normalized Nusselt evolution is flattened with respect to RANS simulations. The latter provides higher amplitude fluctuations in both the radial and span-wise directions. The results indicate that unsteady approach is more reliable in capturing jet flow behavior within the cavity and heat transfer performance at the leading edge wall, under the effects of rotation.
Emissions Comparison of 100% SAF With Bio-Aromatics and Conventional (Fossil) Jet Fuel
Authors: Jarin Jean-Baptiste , Champion-Réaud Jean-Louis , Sallinen Reetu , Steenwinkel Edgar 
Published: August 2024

Abstract
It is recognized that Sustainable Aviation Fuels (SAF) will play a significant role in the decarbonization of air mobility and various pathways and feedstocks are considered for their production. This may lead to differences in chemical and physical properties when compared to conventional, fossil, aviation fuel (CAF). SAF available today are blended with CAF and after blending they are compliant with the Jet Fuel norm (ASTM1655). But the goal of achieving 100% SAF could be problematic, as the absence of aromatics, one of the characteristics of SAF produced today, could lead to leaks in the seal. Adding renewable aromatics (Synthesized Aromatic Kerosene, or SAK) to the SAF is therefore seen as an opportunity to reach 100% SAF without impacting the aircraft and airport’s fuel infrastructures, potentially enabling a faster decarbonization of the sector. In this study, we have compared the emissions of a 100% SAF which contains 9% of SAK issued from the biomass (SAF-SPK/A) with a CAF.
Performance and behavior: The tests did not identify any performance differences between the two fuels, including turbine reactivity and equipment degradation. This was later confirmed by Bell Helicopter during an experimental test flight campaign. Emissions: the lower CO2 impact is mainly due to the life cycle analysis of the SAF, but the test also showed reduced CO2 emissions during the combustion. While NO and NOx were found equivalent, significant reduction in CO and soot (Smoke Number, SN) were measured: −20 to −50% depending on the mass fuel flow. These improvements could be explained by the lower content of aromatics as well as the nature of these aromatics and this will be further investigated in future studies.
IndRNN-Based Data-Driven Modeling Integrated With Physical Knowledge for Engine Performance Monitoring
Authors: Xiao Dasheng , Xiao Hong , Wang Zhanxue 
Published: August 2024

Abstract
Monitoring the whole performance status of aircraft engines is of paramount importance for ensuring flight safety, control system and prognostic health management. This work introduced an aircraft engine deep learning model that integrated with engine physical knowledge. Firstly, component networks were established for each engine component (e.g., fan, turbine, nozzle) using the independently recurrent neural network (IndRNN), self-attention mechanism, and residual network. Subsequently, based on the physical spatial alignment of engine components, the data transfer between component networks was determined to establish the whole engine model. Case studies were conducted on exhaust gas temperature (EGT) prediction for two civil aircraft engines and thrust prediction for another two turbofan engines. When processing the actual engine running data, the data augmentation method was invested to address the issue of non-uniform distribution of engine working states in the training data. Compared with three pure data-driven models based on IndRNN, recurrent neural network and long short-term memory, the model introduced in this work demonstrated superior precision in both steady states and transient states. Specifically, the achieved mean absolute relative error (MARE) was 0.54% for EGT prediction and 0.41% for thrust prediction. When adjusting the time steps, the introduced model showed steadier predictions with minimal MARE fluctuation compared to the three pure data-driven models, enhancing overall predictive stability.
Numerical-Experimental Comparison of the Performance of a Mixed-Flow Fan Designed for Electric Vehicles
Authors: Aldi Nicola , Pinelli Michele , Piovan Mattia , Suman Alessio , Zanini Nicola , Mollica Enrico , Menichini Filippo 
Published: August 2024

Abstract
Due to the ecological-green transition, Battery Electric Vehicles (BEV) will replace the Internal Combustion Engine (ICE) ones, since they are less pollutant in terms of carbon and noise emissions. Inside a BEV one of the major sources of noise, especially during battery charging, is related to the cooling system, which is composed of one or two axial fans and the heat exchangers. This work aims to investigate the possibility of reducing the noise emission, and increasing the efficiency of the cooling system, using a mixed-flow fan rather than an axial-flow one. In fact, it can supply comparable performances when compared to an axial fan but with quite lower rotational speed, i.e. with lower noise and reduced friction losses. In the first phase of the present work, the mixed-flow fan has been designed with a design procedure based on the available literature, starting from the inputs received from the customer, i.e. geometrical constraints, pressure rise, and power consumption. After this preliminary design process, detailed CFD simulations have been performed in order to validate the assumptions made. Thereafter the initial fan geometry has been modified to take into account the manufacturability constraints, related to the plastic injection molding process, and the fan geometry has been optimized and finalized. Different numerical approaches have been investigated to evaluate the influence of the numerical setup on the results. Finally, the optimized geometry has been prototyped and tested in a standard airflow test bench in order to assess the real performance of the mixed-flow fan and to identify the most suitable numerical approach that should be used to simulate this kind of turbomachine.
Flutter Parameter Study on a Complex Inlet Swirl Distortion Generator
Authors: Hefner Cole , Guillot Stephen , Gillespie John , Hayden Andrew , Lowe Todd , Untaroiu Alexandrina 
Published: August 2024

Abstract
StreamVane devices consist of a custom designed complex vane pack that is used to produce inlet swirl distortion for fan tests, compressor tests, and ground testing of jet engines. Due to being placed upstream of these expensive test rigs, their structural integrity is very important. Since very little research has been conducted on flutter of complex vane packs like StreamVanes, this work focused on examining flutter of one of these models in more detail as well as studying the effects of various parameters on the critical flutter speed and frequency of these devices. For this study, a quad swirl StreamVane that was previously experimentally found to flutter was further analyzed using unsteady CFD with periodic mesh deformation based off the mode shape. This showed the flow in the passage between the fluttering vanes switching between a choked state and a subsonic state as the vanes moved together and apart from each other. This initial quad swirl model was then used as the basis for a series of small-scale flutter tests. These tests examined multiple parameters including chord length, vane thickness, blockage effects, and turning angle variation. To further analyze any potential causes of the excitation, oil flow visualization was conducted and found to show some leading-edge separation and minor corner separation but no pattern to indicate these flow features are responsible for the unsteady loading driving flutter. The results in this paper provide insight into the flutter behavior of these complex vane packs.
The Onset of Low Reynolds Number Separation in High-Lift High-Work LPT Passages
Authors: Marks Christopher R. , Fletcher Nathan , Donovan Molly , Clark John P. 
Published: August 2024

Abstract
Low Reynolds number conditions occur over portions of the operating envelope in the low-pressure turbine section of aircraft engines, leading to a reduction in efficiency due to laminar boundary layer separation. The resulting “Reynolds-lapse” can greatly influence the performance of high-lift high-work low-pressure turbine blades. While the mid-span Reynolds-lapse phenomena has attracted much attention in the literature, the focus of the current paper is on the evolution of separation across the blade span. Extensive experimental measurements were obtained in a low-speed linear cascade arrangement of low-pressure turbine research profiles. Two different high-lift (Zw = 1.78 and Zw = 1.88) high-work profiles were considered. Multiple planes of high-speed particle image velocimetry were acquired to study the development of separation across the span as flow conditions were varied through the Reynolds-lapse curve. In the case of the Zw = 1.78 airfoil, the suction surface boundary layer separation bubble size increases steadily and monotonically as Re is decreased to the lowest Reynolds number measured, Re = 15k. However, the Zw = 1.88 profile experiences a rapid onset of un-reattaching separation at the knee in the curve. A unique four camera composite velocimetry measurement of the suction surface flow was used to capture the progression in separation across the span. A difference in the onset of separation between the two blade profiles was observed. In one case, the separated flow region progressed from the endwall toward the mid-span; and in the other blade set, it progressed from the mid-span toward the endwall. The findings provide a new and deeper understanding of the separation development across the passage of high-lift high-work turbine blades at low Reynolds number.
Assessing the Environmental Impact of Aircraft / Engine Integration With Respect to Contrails
Authors: Ramsay Joseph , Tristanto Indi , Shahpar Shahrokh , John Alistair 
Published: August 2024

Abstract
In recent years, the radiative forcing of aircraft contrails and aircraft-induced contrail cirrus have been highlighted as a serious short-term climate impact of the aviation industry. Greater understanding of factors influencing contrail properties are required if routes to mitigation are to be explored. In the current work, a parametric turbofan powered aircraft model has been created to study the impact that aircraft design, in particular the interaction between the jet and wingtip vortex, can have on ice crystal formation, growth, and dynamics within a contrail. To investigate this, a contrail microphysics module has been developed and integrated within Rolls-Royce in-house Hydra CFD code. Three-dimensional Reynolds-Averaged Navier-Stokes simulations are conducted over the jet and early vortex regime, covering an area which is often simplified in most contrail modelling approaches. It is found that the position of the engine along the wing of an aircraft can impact the formation of the wingtip vortex, altering the contrail properties and distribution downstream of the aircraft. The effect of multi-engine architecture is also assessed and shown to influence the magnitude of exhaust entrainment into the vortex.
The Investigation of Inlet Condition Effect on the Surge Recovery Process of a S-CO2 Radial Compressor
Authors: Kim Gihyeon , Lee Jeong Ik 
Published: August 2024

Abstract
The supercritical carbon dioxide (S-CO2) Brayton cycle is a power conversion cycle that utilizes supercritical carbon dioxide as the working fluid. One of the main characteristics is that the compressor operates with inlet conditions close to the critical point. However, approximating the S-CO2 compressor as an ideal gas turbomachinery model is limited by the rapid change in fluid properties near the critical point. Additionally, unlike most air Brayton cycles, the S-CO2 Brayton cycle is designed as a closed loop. To study the surge recovery process of the S-CO2 compressor, this study utilized an integral test loop with a turbo-alternator-compressor equipped with active magnetic bearings. Surge recovery performance tests were conducted at various speeds to investigate the effects near the critical point. Surge recovery performance was observed by reducing the compressor mass flow rate to induce a surge and then restoring the flow rate. The compressor instability was classified into surge and stall on the basis of speed, and the change of compressor inlet conditions affected the surge recovery performance of the S-CO2 compressor. The experimental results propose modifying the Greitzer B parameter as a means of estimating surge and stall in S-CO2 compressors.
Aero-Engine Remaining Useful Life Prediction via Physics-Informed Self-Attention Encoder
Authors: Zhang Xuanwu , Lou Jiayue , Zhang Jifa , Zheng Yao , Xia Yifan 
Published: August 2024

Abstract
Prediction of aero-engine remaining useful life (RUL) is crucial for the aeronautic industrial. In recent years, the deep learning enhanced methods for the aero-engine RUL prediction has attracted more and more attention by the community. However, how to correctly process information, extract features and carry out feature fusion from cluttered sensors is still a challenging problem. In this paper, a hybrid framework containing a method of data reduction and feature extraction based on physics-informed self-attention encoder (PISAE) is proposed to predict the RUL of aero-engines. The self-attention mechanism is used to process the data. In the part of feature extraction, the encoder-decoder architecture is applied to reduce the data dimensions and extract the features. In the encoder section, data features are embedded in vectors of low dimensions. Then, a neural network based on the self-attention mechanism is constructed to make predictions of the RUL. Physical information is embedded into the training process. The proposed framework is experimentally evaluated on the Commercial Modular Aeronautical Propulsion System Simulation (C-MAPSS) dataset. Results show that the framework can effectively improve the prediction accuracy of the remaining service life by information processing and feature extraction. In addition, the proposed framework improves the interpretability in the process of data processing and feature extraction, and has high applicability in predictive maintenance.
A Data-Driven Method for Predicting the Overall Performance of a Three-Rotor Dual-Variable Cycle Engine
Authors: Yuan Qiyu , Qiu Tian , Qu Guixian , Liu Peng , Liu Chuankai , Ding Shuiting 
Published: August 2024

Abstract
In order to meet the high maneuverability and long-range design requirements of the new generation of aeroengines, variable cycle engines (VCEs) with variable geometry characteristics and multiple mode adjustments have become a mainstream research direction. A three-rotor dual-variable cycle engine (TDCE) configuration with both turbofan and turbojet modes is proposed for the 0–30 km, 0–5 Ma flight envelope. Based on an integrated aeroengine simulation platform (IASP), a comprehensive performance model of the variable cycle engine is established, and the engine characteristics under four modes, low-subsonic mode (M-Lsub), middle-supersonic mode (M-Msup), high-supersonic mode (M-Hsup), and top-supersonic mode (M-Tsup) are analyzed with various adjustment features. For this configuration, a surrogate model for predicting overall performance deviations is established using a radial basis function neural network to quantify the impact of design performance deviations of rotating components on the overall engine performance parameters. neural network. The overall engine prediction model based on the Radial Basis Function (RBF) neural network approach shows high accuracy with an R-squared value exceeding 0.85, according to the experimental results. This indicates that the model fits the test set well and allows for a rapid evaluation of the effect of component design on overall performance. The outcomes of the investigation can provide technical assistance in the design of the TDCE configuration and enhance the effectiveness of the collaborative design procedure for advanced aeroengines.