bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Evaluation of a Premixed Swirl-Stabilized Gas Burner With a Focus on Mixture Stratification
Authors: Payri Raul , García-Oliver José M. , Martí Gómez-Aldaraví Pedro , Ramírez-Correa Elkin 
Published: August 2024

Abstract
The present work reports an experimental evaluation of the flame stabilization, structure and pollutant emissions for a swirl-stabilized premixed burner at atmospheric conditions. The burner has been designed to accommodate two inlet streams, namely a swirling air and a non-swirling fuel-air mixture, which are fed into a mixing chamber. By modifying the air mass distribution between the swirling and non-swirling streams, the burner can produce different swirl numbers at the chamber, as well as different fuel-air mixture stratification. A central tube acts as a bluff body to help stabilize the flame.
Experimental diagnostics include high speed flame visualization in terms of OH* chemiluminescence, and NOx pollutant at the burner outlet. The study has been carried out using both hydrogen and methane as fuels. A sweep of conditions has been carried out to identify the lean blow-off limit over the burner operational map. Results for methane indicate that the lean blow-off limit is strongly affected by the air distribution between the swirling and non-swirling parts. In contrast, air distribution has a more significant effect on NOx emissions for hydrogen. Different flame shapes are analyzed over the operational map, where strong differences in lift-off, flame width, and reaction zone chemiluminescence have been identified.
Accuracy Analysis of Multi-Plane Unbalance Identification Using Different Model Order Reduction Techniques
Authors: Shehzad Khurram , Ranjan Gyan , Choudhury Tuhin , Nutakor Charles , Sopanen Jussi 
Published: August 2024

Abstract
The estimation of multi-plane unbalance in rotating machinery is a field of active research. To identify the magnitude and phase of residual unbalances from vibration responses, different model-based identification algorithms are being used. However, when the number of measurement planes is limited, model reduction techniques are typically employed in these identification algorithms. While these techniques can reduce the model’s degrees of freedom (DOFs), they may also affect the system’s dynamic behavior. Therefore, it is necessary to examine the accuracy of the prediction of the faults in scenarios where the model is reduced. This study compares various model-based methods for detecting imbalances at multiple planes. It involves implementing different reduction techniques, including Guyan reduction, dynamic reduction, dynamic reduction with gyroscopic effect, and system equivalent reduction expansion process (SEREP). As an example, rotor bearing systems with multiple disks located between bearings and in overhung conditions are considered to ensure the algorithm’s general applicability in industrial applications with various impeller configurations. The vibration responses of the disk locations are taken into account for estimating the unbalances. It is observed that the accuracy of estimation varies greatly with different reduced-order models, particularly in the proximity of resonance and at higher speeds due to the presence of gyroscopic effects in the system. The percentage error in estimating unbalance is compared using different reduction methods across multiple operating speeds. These findings help to determine the appropriate speed range for the applicability of different reduction methods to be used in balancing.
Heat Transfer Enhancement of Wedge-Shaped Channels Using the Interpretable Multi-Objective Generative Design Method
Authors: Kaibin Hu , Shengquan Zhong , Yu Rao , Li Yang 
Published: August 2024

Abstract
Gas turbine blade cooling is crucial for enhancing turbine efficiency and durability. In particular, wedge-shaped channels are commonly used for trailing edge internal cooling. However, conventional cooling channel structures such as pin fins have limitations in achieving uniform heat transfer. To address this issue, a new approach using bionic cooling structures generated through self-organized equation had been proposed. Additionally, a multi-objective Bayesian approach is utilized to optimize the topological parameters, with comprehensive emphases on two specific design objectives: improving heat transfer and reducing pressure loss. Simultaneously, data mining techniques are applied to automatically extract design principles and clarify the enhanced performance characteristics resulting from optimization. Then the study investigates the performance of optimized self-organized structures in comparison to pin-fin structures. Results show that self-organized structures provided better heat transfer performance with lower pressure drop, and more uniform temperature distribution. Specifically, under the same level of pressure loss, the selected self-organized structure increases heat transfer by 35%. Data mining identifies the material orientation and the material generation on the left side region as critical factors in topological structures, significantly influencing pressure loss and overall heat transfer efficiency. This research highlights the potential of self-organized structures as a design methodology for turbine blade cooling.
Using Hydrogen for the Generation of Non-Propulsive Energy in Civil Aviation - Design and Performance of Combined Micro Gas Turbine and Organic Rankine Cycle Systems
Authors: Arenas-Fernández Alejandro , Rodríguez-de Arriba Pablo , Escamilla-Perejón Antonio , González-Almenara Rafael , Sánchez David 
Published: August 2024

Abstract
The interest in using hydrogen for civil aircraft propulsion is well known and has already been explored by the aero industry extensively. In this context, Iron NPE is a 25 M€ project funded by the Government of Spain with the aim to develop an efficient, flexible and compact generator of non-propulsive energy running on hydrogen. Aiming to achieve very high efficiency by exploiting the favourable boundary conditions at flight altitude ambient temperature as low as −65°C), micro combined cycle systems are explored as an alternative to the more standard solution based on PEM fuel cells. These systems deliver a stream of hot gases which is harvested by a bottoming Organic Rankine Cycle system downstream, to further enhance global performance.
This paper presents a preliminary analysis to benchmark the generation of non propulsive energy based on fuel cells, explore the thermodynamic potential of stand-alone of micro gas turbines with small and large recuperators and assess the benefits of sacrificing micro gas turbine performance in order to enhance waste-heat-to-power recovery in a bottoming organic Rankine cycle. Key aspects of the independent systems involved as well as the integrated combined system are assessed. Eventually, it is revealed that the utilisation of combined systems with bottoming ORC units running on either propane or isobutane enable close to 50% conversion efficiency. Moreover, even if the efficiency attained by the system incorporating a bottoming isobutane ORC system is slightly higher, it seems that adopting a subcritical ORC unit running on propane allows for easier and more compact design of components at minimum performance drop.
Predicting NOx Emissions of a Lean Hydrogen Flame Using High and Low Order CFD Models
Authors: Amerighi Matteo , Andreini Antonio , Orsino Stefano , Verma Ishan , Yadav Rakesh , Reichel Thoralf , Tanneberger Tom , Paschereit Oliver 
Published: August 2024

Abstract
Recent efforts in numerical methods to study hydrogen combustion have allowed the development of affordable and reliable strategies that can reproduce the main structure of the flame. Although this objective represents a vital goal of the design process of a new combustor, properly estimating the emission remains an aspect that must be further investigated. In fact, due to the lack of experimental data, few numerical works addressed the evaluation of NOx emissions in hydrogen-fueled rigs. The present work aims to study turbulent combustion and NOx emission formation through different numerical approaches on a laboratory-scale atmospheric rig. The burner consists of a swirl-stabilized, technically premixed hydrogen-air flame, with detailed NOx emissions estimated via an experimental campaign at the Technische Universitat Berlin (TUB). A first estimation is obtained through a high-fidelity simulation performed in order to assess the capability of a computationally expensive strategy to estimate NOx emissions. A species transport simulation adopting a Thickened Flame Model in which NOx chemistry is included in the chemical mechanism is carried out. After that, a cost-efficient method is explored, allowing a quick assessment of the NOx. With this approach, named LES-to-RANS, time average fields are evaluated from an LES species transport simulation with simplified chemistry. In particular, the NOx equations are performed on a frozen RANS framework as a post-processed stage. The capabilities of the model are then tested under two different scenarios: adiabatic and non-adiabatic wall temperature. The computational accuracy of each approach is compared and discussed, with emphasis on computational cost.
Effect of Turbulence Transition Models on the Flow Field of a Centrifugal Compressor Operating in Low Reynolds Number Condition
Authors: Kong Weihan , Wang Baotong , Zheng Xinqian , Ishikawa Yoshihiro , Kanzaka Tadashi 
Published: August 2024

Abstract
Centrifugal compressors are widely employed in various small power systems, such as automotive turbocharger, electric compressor and centrifugal chiller. As a key component of such power systems, the performance of centrifugal compressors plays an important role for the energy conversion efficiency. Numerical approach is widely applied to evaluate the performance of compressors, and accurate simulation of flow behavior is the foundation to study the flow loss mechanism and improve the performance. In the small compressor with low working Reynolds number, the boundary layer transition is an important flow feature, and a reliable turbulence transition model is indispensable to correctly capture the behavior of boundary layer development and transition. Therefore, the capability of turbulence transition model is critical to accurately simulate the flow pattern of the compressors. The motivation of this paper is to establish applicable CFD method which can guide the design of small size centrifugal compressors suffering from low Reynolds number effect. As the first step to realize this target, the effects of various transition models including Standard SST model, γ model, γ-Reθ model and Improved γ model on the flow feature in a centrifugal compressor operating in a low Reynolds number condition are carefully investigated by comparing the overall performance and flow details. Based on the results, the γ-Reθ model shows superior capability to capture the flow pattern and evaluate the performance while operating in a low Reynolds number condition.
Numerical Study of Flow and Heat Transfer Characteristics in Channel With Dumbbell Pin-Fin
Authors: Yan Shuangjie , Liu Jianjun , An Baitao 
Published: August 2024

Abstract
In this paper, numerical simulation was conducted to investigate the flow and heat transfer characteristics in the channel with dumbbell pin-fin, and the channel with circular pin-fin is used as the baseline to evaluate the enhanced heat transfer performance of the dumbbell pin-fin. The dumbbell pin-fin consists of thick segment at both ends and thin segment in the middle. The effect of length and diameter of the thin segment is investigated at Reynolds numbers ranging from 10000 to 40000. Numerical simulation results show that either extending the length or shrinking the diameter of thin segment of the dumbbell pin-fin, can significantly reduce the friction factor with slightly changing the Nusselt number. Dumbbell pin-fins induce relatively small wake, which enhances the heat transfer in the first three rows of the pin-fin channel. The dumbbell pin-fin reduces the stagnation resistance while disturbing the flow, which weakens the turbulence and heat transfer on downstream of the pin-fin channel compared with the baseline pin-fin. The structural parameter Dt/D of the dumbbell pin-fin has a greater impact on the overall thermal performance than the parameter C/H. The dumbbell pin-fin with Dt/D = 0.4, C/H = 0.5 produces the greatest overall thermal performance, which increased by 22.5%,16.8%,16.6% and 12.7% compared with the baseline pin-fin at Reynolds number of 10000, 20000, 30000 and 40000, respectively. The dumbbell pin-fin can be used to reduce the flow resistance of turbine trailing edge channel while ensuring a certain heat transfer.
ASME PTC 10-2022: Concise Update Overview
Authors: Taher Matt 
Published: August 2024

Abstract
ASME PTC 10 is a globally recognized code for performance testing of axial and centrifugal compressors. The ASME PTC 10-2022 has gone through a major revision after 25 years since its previous revision in 1997. Among the major changes in the revised code are (1) the use of real gas relationships instead of the ideal gas model (2) the adoption of a polytropic process throughout the code (3) with new calculation methods for the polytropic work and the polytropic efficiency, (4) an updated definition of the polytropic process based on a constant polytropic efficiency along the polytropic path, (5) an updated range for allowable test machine Reynolds number, (6) a new correction method for the Reynolds number effect (7) new requirements for flow rate corrections based on difference of leakage ratios, (8) multi-point test requirements to verify performance curves, (9) test stabilization for readings and calculated values, (10) updated requirements on test instruments, test data treatment, and methods of measurement, (11) new methods to calculate test total pressure and temperature, (12) updates on casing heat transfer for test power measurements (13) a new chapter on test uncertainty, (14) a new non-mandatory appendix on performance testing of back-to-back compressors, and (15) the addition of metric units.
This paper aims to present a concise overview of the significant technical updates incorporated in the ASME PTC 10-2022 revision as perceived by the chair of its code committee.
The Design of High Temperature Heat Pump Compressor Using the Inverse Design Method
Authors: Zhang Luying , Zhang Jiangnan , Zangeneh Mehrdad 
Published: August 2024

Abstract
High temperature heat pumps (HTHP) have the potential to reduce CO2 emission in multiple industrial processes. It is a key technology for the heat recovery from various sources and will contribute to the decarbonization pathways. The selection of high temperature refrigerant is important to the system performance, cost-effectiveness and environmental-friendly requirement. It also leads to some challenges for the compressor design, which is an area under active development. In this work, a methodology for HTHP centrifugal compressor design is presented. The heat pump cycle analysis and the compressor meanline design are coupled in the initial phase to study the selection of refrigerants and its impact on compressor design. Following this, the impeller was designed using a 3D inverse design method. Automatic optimization was carried out to optimize the impeller performance. The downstream volute was also designed by using a unique inverse design method. Finally, the performance of the compressor stage was verified by computational fluid dynamics simulations. The structural integrity of the compressor was also examined by finite element analysis. The result shows it is important to couple the compressor design with the refrigeration cycle analysis and through the state-of-art compressor design/optimization techniques centrifugal compressor designs can be efficiently generated for HTHP applications.
On the Challenges of Integrating a Rotating Detonation Combustor With an Industrial Gas Turbine and Important Design Considerations for Row-1 Blades
Authors: Rathod Dharmik S. , Meadows Joseph 
Published: August 2024

Abstract
With the ever-growing demand for power generation to support the world economy and electric transportation needs, efficient gas turbine power cycles need to be investigated to match the anticipated high demands of the future. Decarbonization efforts around the world to achieve Net Carbon Zero by 2050 have also brought many new challenges for the development of these systems due to the unique constraints imposed by less carbon-intensive fuels. In this effort to increase the efficiency and performance of such gas turbine power cycles, pressure gain combustion (PGC) has gained significant interest. The potential for an increase in the thermodynamic efficiency over the constant-pressure Brayton Cycle has made detonation combustors, a type of PGC, an attractive alternative to traditional deflagration-type combustors. Since Rotating Detonation Combustors (RDC) can provide a quasi-steady mode of operation when compared to Pulse Detonation Combustors (PDC), research has been triggered to integrate RDC with power-generating gas turbines. However, the presence of subsonic and supersonic flow fields which are generated due to the shock waves that stem from the detonation wave front and the highly non-uniform temperature and velocity profiles may cause a depreciation in the turbine performance.
The current study seeks to investigate the challenges of integrating the RDC with nozzle guide vanes (NGV) of an industrial, can-annular gas turbine and attempts to understand the major contributors that impact efficiency and identify the key areas of optimization that need to be considered for maximizing performance. To match F-class engine conditions, a geometric model of RDC developed by the Air Force Research Laboratory (AFRL) was scaled to achieve the desired flow conditions. The RDC was integrated with the NGVs through a non-optimized straight duct-type geometry with a diffuser cone. 3-Dimensional Numerical analyses were performed to investigate sources of total pressure loss and to understand the unsteady effects of RDC which contribute towards the deterioration of performance. The entropy generation at different regions of interest was calculated to identify the major irreversibilities in the system. Finally, total pressure and temperature distribution along the radial direction at the exit of the transitional duct is presented to understand the various constraints imposed by the RDC when integrating with an Industrial gas turbine engine NGV.
A Novel Thermally Integrated CO2-Carnot Battery Utilizing Cold Thermal Storage
Authors: Shamsi Syed Safeer Mehdi , Barberis Stefano , Burlando Andrea , Maccarini Simone , Traverso Alberto 
Published: August 2024

Abstract
The growing integration of renewable energy sources in the energy grid presents challenges related to intermittency and negative pricing, necessitating large-scale energy storage solutions. Pumped Thermal Energy Storage (PTES) is an innovative system designed to address these issues by storing and delivering substantial energy in the form of heat using thermal heat pump and power cycles respectively. High temperature heat pump development is crucial to the deployment of PTES as it needs to store heat at &gt; 450°C above the ambient temperature to ensure a reasonable round trip efficiency (RTE). Currently however, it is not a technological possibility for heat pump machinery to achieve these temperatures even with integration of freely available heat sources (200°C to 400°C) which can support the heat pump cycle from a RTE standpoint. This study explores a potential layout of TI-PTES system that exploits commercially available equipment by storing heat below the ambient temperature while still being able utilize the freely available heat source (Solar, Waste heat, biomass etc.) to support the overall RTE, in the power cycle instead. The charging phase employs a well-established CO2-refrigeration cycle to accumulate energy below the ambient temperature in a cold thermal storage. While the discharging phase runs a trans-critical CO2 power cycle between the freely available heat source and the cold thermal storage. Overall, offering a practically implementable model for the PTES system with market available components. The study investigates design of this innovative system presenting the relevance of different operating and machine parameters as well as the contribution of freely available heat source in the overall performance. Finally benchmarking the technology with other long duration energy storages.
Performance Evaluation of Different Rotating Detonation Combustor Designs Using Simulations and Experiments
Authors: Raj Piyush , Talukdar Shaon , Meadows Joseph , Agrawal Ajay 
Published: August 2024

Abstract
Rotating Detonation Engines (RDEs) present a potential avenue for enhancing the efficiency of gas turbine combustors through the utilization of a detonation-driven process. However, integrating an RDE with a downstream turbine poses a significant challenge due to the shock-laden and highly unsteady nature of the RDE exit flow, coupled with a high degree of flow periodicity. In contrast, gas turbines are designed to operate with relatively small velocity and temperature fluctuations at the turbine inlet. The objective of the present study is to develop an understanding of how geometric profiling can improve RDE performance and mitigate exhaust flow field unsteadiness. Three RDE designs are analyzed: an annular combustor with a constant cross-sectional area, an annular combustor with a converging nozzle near the exit, and an annular combustor with a rapid to gradual (RTG) area convergence. Three-dimensional unsteady reacting simulations are conducted for each configuration using the same fuel-oxidizer composition and mass flow rate condition. All simulations are validated against experimental measurements, and RDE performance is assessed based on total pressure gain/loss, unsteadiness at the exit of the RDE, and detonation effectiveness. Results show significant performance improvement for both the convergent nozzle and the RTG profile compared to the constant cross-sectional area configuration, and the RTG design performed better than the convergent nozzle design. Therefore, strategically constricting the flow in an RDE can be used to optimize the performance of an RDE and should be considered in future designs.