bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Design of Integrated Thermal Management Systems for eVTOL Aircraft
Authors: Kang Sangkeun , Saias Chana , Roumeliotis Ioannis , Broca Olivier 
Published: September 2023

Abstract
Vertical take-off and landing aircraft equipped with hybrid or fully electric propulsion systems have gained interest for urban air mobility applications. Besides the low energy density of state of art electric systems, their strict operating temperature requirement and low-grade heat highlight the importance of effective thermal management system design. This paper aims to establish a design process for the thermal management system for a parallel hybrid electric tiltrotor and showcase it for a system consisting of direct ram-air cooling cold plate and phase change materials. The cold plate is designed for cruise conditions and used as heat acquisition and cooling system, whereas the phase change materials is used as a heat storage system when ram air is limited. Three sizing conditions are considered comprising the baseline design mission, a certification condition for One Engine Inoperative (OEI) and an off-design mission. The effects of thermal management system integration on overall performance are quantified and discussed. The results indicate that designing the system for the baseline sizing mission results in a 5% increase in fuel burn per payload relative to the equivalent counterpart without thermal management consideration. This penalty increases to 14% when certification requirements are accounted. It is highlighted that tor shorter mission thermal management is the limiting factor for battery utilization, hence the expected benefits are significantly reduced. As electric components technology increases thermal management becomes less sensitive to the sizing conditions.
Experimental and Computational Study on the Impact of Aerodynamic Load Distribution on Aerodynamic Performance of Variable-Speed Turbine Blade
Authors: Fan Du , Zhou Zhihong , Liu Huoxing 
Published: September 2023

Abstract
Improving the adaptability of variable speed turbine blades to incidence angle by optimizing blade aerodynamic load design is one of the effective technical means to realize the efficient operation of variable-speed turbine blades in a wide range of incidence angle and improve the performance of variable speed turbine. In this paper, cascade experiments and numerical simulation study are carried out under a wide range of incidence angles for three variable-speed turbine blades with different aerodynamic load distributions. The results show that, under the positive incidence angle, the sharp increase of loss mainly occurs in the front part of the suction surface, while the loss increase in other areas is not obvious. Under the negative incidence angle, the sharp increase of loss mainly occurs in the middle and rear parts of the pressure surface. Under the extreme negative incident angle, the increase of loss caused by the middle and rear part of the pressure surface accounted for more than 90% of the total loss increment, while the loss caused by the middle part of the suction surface affecting the flow at the rear of the suction surface accounts for less than 10%. The suitable fore-loaded blades design can greatly broaden the working range at negative incidence angle, while aft-loaded blades can slightly reduce the blade loss at positive incidence angle.
Numerical Analysis of Flame Shape Impact on the Performance of Fuel Staging in a Lean-Burn Aeronautical Burner
Authors: Cunha Caldeira Mesquita Léo , Vié Aymeric , Ducruix Sébastien 
Published: September 2023

Abstract
The BIMER combustor is a lab-scale burner investigating fuel staging techniques as a stabilisation strategy for lean premixed prevaporized combustion for aeronautical applications. Two stages compose its injection system: the pilot and the multipoint stages. The staging factor is defined as the ratio of fuel mass flowrate injected through the pilot stage over the total one. As three flame shapes were found experimentally, Large-Eddy Simulations are performed in this study to assess the impact of the flame shape on the combustion regime and stability of the burner. Two operating conditions were explored experimentally (pilot-only and multipoint-dominated) to validate the simulations and compare the three flames. An additional multipoint-only condition is also investigated for the V flame. The burning regimes (premixed and non-premixed) and noise signatures (as a function of fuel staging) were compared to check whether these flames could benefit from the staging strategy. The M and Tulip flame combustion regimes are little affected by fuel staging, remaining mostly premixed and non-premixed, respectively, regardless of fuel staging. In opposition, the V flame changes from being mostly non-premixed to completely premixed, when the injection is changed from pilot-only to multipoint-only. For the same staging evolution, the V flame also emits less noise for the investigated points. These results show that the V flame shape is the only one that allows this burner to benefit from an efficient fuel staging strategy.
Conjugate Heat Transfer and Thermal Stress in an Impingement Cooling Unit for Gas Turbine Vane
Authors: Wang Shanyou , Li Xueying , Ren Jing 
Published: September 2023

Abstract
Impingement cooling is widely used in gas turbines because of its excellent local heat transfer capability, and it plays an important role in the next generation of double-wall cooling technology. However, it induces inhomogeneous temperature fields as well as thermal stress fields. In this paper, the conjugate heat transfer and thermal stress characteristics are investigated for an impingement unit including a single round nozzle and solid plate with uniform heat flux on the heated surface through an experimentally validated numerical approach. The studied operating parameter are Reynolds number (from 10000 to 30000), nozzle-to-plate distance ratio (from 2 to 10), and thickness of solid plate (108 mm and 50 mm). The results show that the Nusselt number distribution along radius may have two maxima at a small impingement distance which is driven by the mismatch of maximum wall shear stress location and maximum near-wall turbulence kinetic energy location. Considering the uneven heat transfer distribution as a boundary condition of solid thermal conduction, thermal conduction would reform the heat flux which makes the uniform heat flux boundary condition on the heated surface into uneven heat flux distribution on the impinged surface. The temperature can be lowered and distributed more evenly by increasing the thermal conductivity of the plate. In contrast, the temperature can be lowered but distributed more unevenly by reducing the thickness of the plate. The flat plate expands into a shape with a thin center and thick edges due to the uneven temperature field. This research illuminates the coupling mechanism between convective heat transfer, solid heat conduction, and thermal stress, which has significance for the prediction of gas turbine vane metal fatigue life.
Structural Assessment of Instrumented Parts for Gas Turbine Flange to Flange
Authors: Satheesh Aparna , Soman Abhimanyu , Santhanagopala Krishnan Babu , Reddy Peddi Mallikarjuna , Manoharan Sambandam 
Published: September 2023

Abstract
Market demands new gas turbines or enhancement of an existing gas turbines to fulfill its demand from time to time. These demands are due to changing environmental regulations, market competition, energy efficiency, technological advancements, change in fuel type. Any new GT product enhancement requires validation to understand capability of subsystem behavior and to gain more confidence on performance improvement. Several instrumentations are required to measure these responses at identified locations from different subsystems in gas turbine during prototype testing. Gas turbine is tested with all these instrumentations with several variations in operating parameters to gather actual responses from gas turbine performance and its subsystem. These instruments require modification in subsystem components to gather data and cable routing to send these data to acquisition system. Pressure probes, thermocouples, strain gages, accelerometers, clearance probes, etc. are placed at the identified locations after necessary modifications in subsystem components. These modified features are validated through appropriate analytical assessments to ensure design robustness ensuring successful test campaign and data acquisition. This paper describes those analytical assessments ensuring design robustness.
Steam Turbine Development for Small Modular Reactors
Authors: Ray Suman 
Published: September 2023

Abstract
Introduction of Small Modular Reactor (SMR) technology is likely to play a significant role in energy transition over the next decades by delivering safe, reliable, and sustainable power when required. There are currently more than ninety different types of SMRs in development employing various fuel and cooling solutions. The nearest to market SMR designs are based on state-of-the-art boiling water reactor (BWR) or pressurized water reactor (PWR) technologies and will generate electrical power using steam turbine generator sets operated using an optimized Rankine cycle.
This paper will provide an insight on developments of new steam turbine modules for various inlet volumetric sizes suitable for the 50 MW to 500 MW power range focused on the major design considerations. Even though the steam expansions for the near to market SMRs vary significantly they all have wet steam expansions. The wetness significantly influences the performance and swallowing capacity of the modules. Like industrial or utility power plant of these sizes, steam turbines for SMRs will operate at full speed i.e., 3000 rpm for 50 Hz grids or 3600 rpm for 60 Hz grids although the smallest SMR may have high speed turbines. While the geometric features could be scaled from large nuclear machines with proven operating experience, nucleation effect and water droplet sizes does not scale in the same proportion and hence the impact of wetness needs special consideration. The design features need to reduce water erosion to the largest extent possible by suitably extracting water and hence improving performance and reliability.
All SMR plants are expected to have significantly shorter lead times to commercial operation than today’s large nuclear plant. This being achieved by modularizing the design, constructing in a factory environment, and consequently reducing the erection time and project cost. To achieve a high degree of construction schedule certainty, standardization of plant design across the different site locations is a strong consideration. Selection of a common steam turbine footprint without compromising performance at different cold end conditions is an important contributing factor.
Investigation on the Unsteady Surge Flow Behavior of an Axial-Centrifugal Compressor
Authors: Li Jiaan , Wen Mengyang , Wang Baotong , Zheng Xinqian 
Published: September 2023

Abstract
Compressor aerodynamic instability, such as surge, has been attracting a broad interest in research because of its severe damage to engine performance and structural integrity. Therefore, the knowledge concerning surge flow mechanism and characteristics plays an essential role in taking effective measures of surge recovery. This paper aims to investigate the surge characteristics and distinct instability evolution process of an axial-centrifugal compressor using URANS simulation. Firstly, the CFD model of a combined compressor consisting of one axial and one centrifugal stage was established and validated by experimental data, then the transient characteristics of the surge were obtained. It was found that when the surge occurs, the reverse flow firstly occurs at the diffuser, and an obvious surge cycle was observed at the outlet of the centrifugal stage. In contrast, the pressure at the outlet of axial stage varied linearly with the mass flow without hysteresis phenomenon. When the reverse flow fully developed, the area with reverse flow showed an S-shaped meridional distribution, and higher reverse flow velocity existed at the regions near rotor hub, stator tip, and impeller tip. As a result, these regions were at risk to the detrimental effects of reverse flow and thus, suffer unsteady aerodynamic forces. Furthermore, a full-annulus model was established to study the development of the flow field during the surge inception process. The results showed that rotating stall was first observed near the axial stator hub, while the flow inside the centrifugal stage, worked normally. It indicated that the strong pressurization effect of the downstream centrifugal stage stabilized the operation of the combined compressor even though the upstream axial stage operated at rotating stall.
Continual Adaptation of Compressor Maps During Operation on Measurement Data For Increased Performance of Model-Based Applications in Turbomachinery
Authors: Lorenzen Finn , Schönig Felix , Grote-Ramm Wolfgang , Oliveira Brito Marcel , Neuberger Heiko , Sobolyev Alexander 
Published: September 2023

Abstract
Higher control engineering concepts, including artificial intelligence and model-based control, are recently becoming more popular in complex industrial applications because they enable a significant increase in efficiency. E.g., a model-based approach can be used to enhance the control and monitoring of several coupled components of a larger turbomachinery train. This requires dynamic models of the components, including all machine characteristics, which may experience a shift in their behavior over the course of their lifetime. Such changes occur due to natural fouling, wear of sub-components or external effects induced by maintenance measures. To overcome this problem, we model machine-characteristic maps with artificial neural networks, which may be used as part of prediction models in a model predictive control unit. If an appropriate data set is available, this allows us to adapt the model to the current behavior of the machine without requiring in-depth knowledge about the underlying physics of this “concept drift”, as it is known in literature. However, the training of neural networks is usually connected with high computational effort while the task needs to be executed in real-time during operation. Furthermore, in real operating conditions, machine sensors can only provide labeled data from the current operating point of the machine, which can be stationary for long operation periods of up to several months. In general, this yields only an unrepresentative data subset of the machine-characteristics, which is not sufficient to retrain the whole model to a new state. To solve these problems, we firstly reduce the model adaptation to a convex optimization problem, which can be efficiently solved in real-time conditions. Secondly, we use a specialized data management system with which we can integrate historical data to supplement the unrepresentative data subset. In this paper we show the application of the outlined method on a compressor map and discuss the advantages and requirements of the method in the context of modeling applications for industrial turbomachinery.
Reacting Flow Prediction of the Low-Swirl Lifted Flame in an Aeronautical Combustor With Angular Air Supply
Authors: Hoffmann Sven , Koch Rainer , Bauer Hans-Jörg 
Published: September 2023

Abstract
The development of lean-burn combustion systems is of paramount importance for reducing the pollutant emissions of future aero engine generations. By tilting the burners of an annular combustor in circumferential direction relative to the rotational axis of the engine, the potential of increased combustion stability is opened up due to an enhanced exhaust gas recirculation between adjacent flames. The innovative gas turbine combustor concept, called the Short Helical Combustor (SHC), allows the main reaction zone to be operated at low equivalence ratios. To exploit the higher stability of the fuel-lean combustion, a low-swirl lifted flame is implemented in the staggered SHC burner arrangement. The objective is to reach ultra-low NOx emissions by complete evaporation and extensive premixing of fuel and air upstream of the lean reaction zone.
In the present work, a modeling approach is developed to investigate the characteristics of the lifted flame in an enclosed single-burner configuration, using the gaseous fuel methane. It is demonstrated that by using the Large Eddy Simulation method, the shape and lift-off height of the flame is adequately reproduced by means of the finite-rate chemistry approach.
For the numerical prediction of the lean lifted flame in the SHC arrangement, the focus is on the interaction of adjacent burners. It is shown that the swirling jet flow is deflected towards the sidewall of the staggered combustor dome, which is attributed to the asymmetrical confinement. Since the stabilization mechanism of the low-swirl flame relies on outer recirculation zones, the upstream transport of hot combustion products back to the flame base is studied by the variation of the combustor confinement ratio. It turns out that increasing the combustor size amplifies the exhaust gas recirculation along the sidewall, and increases the temperature of recirculating burned gases. The present study emphasizes the capability of the proposed lean-burn combustor concept for future aero engine applications.
Impact of Flow Unsteadiness on Turbine Airfoil Heat Transfer via Streaming
Authors: Agarwal Tapish , Jacobi Ian , Cukurel Beni 
Published: September 2023

Abstract
Thermal management of turbine airfoils is a critical design consideration, but the impact of unsteadiness on heat transfer of attached flow regions has received less attention in the literature. When turbine surfaces are subjected to unsteady zero-mean flow fluctuations, either naturally or artificially, the mean velocity around them is modified due to a non-linear interaction of fluctuations, known as streaming. In this numerical study, we examine the effect of streaming on heat transfer and skin friction in a simplified model of the flow over a turbine blade. Both heat transfer and skin friction modifications were found to strongly depend on the amplitude and wave speed of the unsteady flow perturbations. Over a wide range of disturbance parameters, skin friction modification was negligible, but a significant effect on heat transfer due to streaming was identified. Moreover, the impact of favorable pressure gradients, which are typical for turbine airfoils, on the streaming phenomena was also considered, and it was found that flow regions of zero-pressure gradient produced the strongest amplification of heat transfer, although the effect of the pressure gradient varied with Strouhal number. Due to its significant effect on wall heat transfer, the streaming phenomenon should be taken into account during the design and measurement of the thermal properties of unsteady systems.
GT36 First Stage Development Enabling Load and Fuel (H2) Flexibility With Low Emissions
Authors: Pennell Douglas , Tay-Wo-Chong Luis , Smith Richard , Sierra Sanchez Patricia , Ciani Andrea 
Published: September 2023

Abstract
In this paper the multi-burner first stage (MBFS) premix system design of Ansaldo’s GT36 constant pressure sequential combustion system (CPSC) is presented. This first stage generates the required inlet temperature to the sequential burner (a parameter essential to regulate for fuel reactivity and stoichiometry): In addition, the first stage maintains optimal NOx and CO emissions and provides for dynamic stability control within the CPSC.
The 8 slot BEV premix burner is introduced, showing its integration into the MBFS and in the overall layout for the CPSC can system. The BEV and MBFS is the culmination of a 10-year development made in tandem with the GT36 can system. The burner is a successor to mature EV and AEV premix burner technologies established in many other methane-based gas turbines. It operates with all necessary fuel blends of methane and hydrogen and creates the inlet conditions with those fuels for the center-body sequential burner to function optimally as the second stage of the can system. The unique use of fuel stages within the BEV burner itself provides the flexibility to overcome the inherent limitations of premix only systems when running with highly reactive fuels. Full pressure can and GT combustion emissions and dynamic data are presented for various loads and fuel compositions, demonstrating the operation, and allowing for tailored solutions in today’s varying GT environment. The system ensures Ansaldo approaches zero CO2 emissions capability for gas turbines in an increasingly hydrogen dominated market.
Analysis of Combustor-Turbine Interaction by Using Coupled and Decoupled Scale-Resolving Simulations Under Representative Operating Conditions
Authors: Tomasello Stella Grazia , Andreini Antonio , Meloni Roberto , Cubeda Simone , Andrei Luca , Michelassi Vittorio 
Published: September 2023

Abstract
The physical phenomena due to the interaction between the combustor chamber and the first stage nozzle arouse an ever-increasing interest. In fact, a complex and unsteady flow field, characterized by a high level of turbulence and temperature distortions, usually can be found at the interface plane between the two hot gas path components, especially with the implementation of lean-burn combustors that allow the reduction of NOx emissions, but at the cost of requiring highly swirled and turbulent flows to stabilize the flame. Such severe conditions at the inlet of the first stage nozzle can have a potential impact on the performance of the component, resulting in a perturbation of the heat transfer, the aerodynamics and the effectiveness of the cooling system. To highlight the risks and uncertainties associated with carrying out decoupled simulations, scale-resolving simulations have been carried out to guarantee an accurate resolution of most of the flow structures while keeping the computational cost low. Firstly, a fully integrated combustor-nozzle setup, including a realistic turbine nozzle cooling system has been investigated under realistic operating conditions. The results have then been compared with those coming from a SBES decoupled simulation of the first stage nozzle alone. In this case, the prescribed time-varying inlet boundary conditions have been extracted from a SBES of the stand-alone combustor where the nozzle has been replaced with a discharge convergent that preserves the Mach number of the NGV while guaranteeing the same throat area. Moreover, in order to assess the discrepancies between different CFD approaches, the results coming from the correspondent preliminary RANS S1N simulation are here also included, by imposing as inlet boundary conditions two-dimensional maps from the time-averaged solution of the precursor SBES of the stand-alone combustor. Thus, the present work concentrates on the comparison and the analysis of numerical SBES simulations of an integrated combustor-NGV configuration and isolated NGV RANS and SBES simulations to assess the impact of the presence of the combustor under realistic operating conditions and realistic annular geometry.