bluuebunny/crossref_metadata_2025_split huggingface dataset:
Energy and Economic Optimization of the Design and Operation of Hybrid Energy Plants Under Current and Future Economic Scenarios
Authors: Castorino Giulia Anna Maria , Losi Enzo , Manservigi Lucrezia , Pinelli Michele , Spina Pier Ruggero , Venturini Mauro 
Published: August 2024

Abstract
At present, renewable energy is commonly expected to be the main source to lead the green energy transition with the target of carbon neutrality. Despite the crucial importance of renewable energy sources, several issues still require the integration with traditional technologies.
Therefore, this paper investigates the design and operation of a Hybrid Energy Plant (HEP) in which several energy systems (renewable energy systems: photovoltaic panels, solar thermal collectors, heat pumps; fossil fuel energy systems: combined heat and power systems, gas boilers, absorption and compression chillers; thermal storage systems) interact in order to identify the best combination and management strategy in terms of fossil cumulative energy consumption and costs.
The concurrent optimization of both design and operation is identified by employing two algorithms, i.e., surrogate modeling optimization algorithm and mixed-linear-programming algorithm. Fossil cumulative energy demand (FCED) or total cost (TC) are separately set as the minimization target, by taking into account the variability of natural gas cost, CO2 emission cost, and electricity prices. Four different economic scenarios, which also consider future trends of costs and energy prices, are analyzed. In addition, a clustering procedure is employed to partition the data of energy demand into clusters in such a manner that their representative objects simulate the entire dataset and the computational time is significantly reduced. The Campus of the University of Parma (Italy) is selected as the case study to validate the methodology.
The proposed approach is demonstrated to be a powerful tool, since it identifies the optimal design and operation of the considered HEP in different economic scenarios. In fact, it allows to save up to 53% of FCED and up to 41% of TC. In addition, the leading technologies towards the 2030 scenario are identified, i.e., combined heat and power plant systems, heat pumps and absorption chillers.
Influence of External Heat Transfer on the Thermo-Structural Stress of a Radial Turbine Wheel
Authors: Balduzzi Francesco , Hoffer Pierre-Alain , Mosciaro Luigi , Mattiello Daniele , Rabbolini Silvio , Pini Nicola , Bianchini Alessandro , Ferrara Giovanni 
Published: August 2024

Abstract
Structural simulations are key for designing the wheel of a turbocharger’s turbine. These simulations enable the assessment of components’ durability and performance in demanding conditions such as extreme exhaust gas temperatures, facilitate the development of the cooling strategies that essential for managing excessive heat, and allow enhancing turbocharger efficiency and preventing catastrophic failures in high-temperature environments. External heat transfer plays a crucial role, since the housing temperature can reach values in the order of 103 K and the contribution of convective heat to ambient air is one of the major sources of loss.
The present paper aims to assess the influence of natural or forced convection between the turbine’s housing and the external ambient on the temperature and stress distributions of the turbine’s wheel. The methodology adopted for the analysis is based on a two-step approach. First, a three-dimensional steady-state conjugate heat transfer (CHT) simulation of the entire turbine stage (including volute, outlet duct, and wastegate valve) is performed to evaluate the temperature field on the metal body of the turbine. Then, the temperature distribution of the body is imported as a load for the thermo-structural simulation of the rotor wheel. The numerical setup was validated against experimental measurements of the temperature of the rotor blade. For the evaluation of the structural behavior of the component, the most critical regions in terms of stresses were identified in the backdisc part of the wheel. The results show the variation of the structural response as the external convection is increased from an ideal adiabatic condition to a forced external cooling condition. The impact of the same on the overall performance limits of the turbine are discussed.
Effects of Curvature and Compound Angle on Cooling Performance and Flow Characteristics for a Combustor Liner With Tangential Effusion Cooling Configuration
Authors: Chen Xuanwu , Zeng Qinghua , Li Ziwan , Xie Pengfu , Yao Min 
Published: August 2024

Abstract
Tangential effusion cooling is considered as an efficient and advanced scheme for combustor liner cooling. Extensive research on tangential effusion cooling has been focused on the outer liner. However, the performance of tangential effusion cooling differs between the inner and outer liners due to their different wall curvatures. In this study, the tangential effusion cooling based on the outer liner and inner liner under the different blowing ratio and compound angle has been investigated numerically to evaluate the overall cooling effectiveness, flow characteristics and heat transfer coefficients. The result shows that the effusion cooling based on the outer liner exhibits superior cooling effectiveness, enhanced film coverage, and reduced heat transfer coefficients compared to that based on inner liner. The overall cooling effectiveness for effusion cooling based on outer liner is about 10% higher than that based on inner liner. The coolant jets attached the wall and flowing spiral forward in the outer liner based model, while the cooling film is detached from the wall and mixed with the mainstream in the inner liner based model. The increase of blowing ratio leads to a larger area-averaged heat transfer coefficient but improves convective heat transfer within effusion holes and enhances overall cooling effectiveness of the liner, particularly for outer combustor liner. The large compound angle has a negligible effect on the area-averaged overall cooling effectiveness but increases non-uniformity in overall cooling effectiveness distribution. This provides a reference and database for the cooling design for annular combustor liner with low cooling air consumption.
Investigation of SPS Tungsten-Lithium Heat Pipe for Primary Heat Exchanger Applications
Authors: M. Prasad Abhilash , Torres Elena , Raju Nandhini , Otto Marcel , Vesely Ladislav , Fernandez Erik , Koyn Zachariah , Kapat Jayanta 
Published: August 2024

Abstract
The demand to reduce carbon emissions and establish sustainable sources of clean energy has increased the interest infusion reactors. Fusion reactors are devices that generate enormous amounts of energy. The result of the thermal energy needs to be transported to improve the reliability and safety of the reactor. One of the potential solutions is a heat pipe. Heat pipes are devices that can efficiently transport heat as well as cool the core of the reactor. Also, it helps for power generation by integrating it with power cycles. In this research, an alkali metal heat pipe, and a Super-critical Carbon Dioxide (sCO2) heat exchanger for a closed Brayton cycle is proposed. It starts from the selection of material and alkali metal for higher temperature application is chosen as tungsten and lithium. Spark Plasma Sintering is used to manufacture tungsten lithium heat pipe samples. The design of the heat pipe designated to transport 20–25 KW of energy. in an array configuration it is capable to transport 1–2 MW of energy. With this design analysis, the interface compactness emerges as a great advantage, allowing it to be used in fusion reactors, waste heat recovery for aircraft engines, gas turbines, and thermal management in hypersonic aircraft.
Control of Shroud Leakage Loss and Windage Torque in a Low-Pressure Turbine Stage
Authors: Christodoulou Loizos , Li Zhihui , Ambrose Stephen , Jefferson-Loveday Richard J. , Jackson Richard , Lock Gary , Sangan Carl , Scobie James 
Published: August 2024

Abstract
As new aeroengine architectures move to larger diameter fans and rotors, the associated increase in weight will need to be counterbalanced by lighter, more compact, and more efficient low-pressure turbines (LPT). Efficiency gains in LPTs can be achieved by reducing the losses associated with the shroud leakage flows. Flow control studies on the topic have traditionally focused on reducing the mixing loss, which constitutes a considerable proportion of the total loss. Nonetheless, increasing engine speeds are driving additional gains obtained by also targeting the reduction of windage losses. Developing a flow control solution with the dual objective of reducing over-tip cavity mixing and windage losses has not previously been attempted. This is a challenge due to conflicting flow control requirements and geometric constraints. Reducing windage loss generally requires increasing the swirl-ratio of the leakage flow, while reducing mixing loss requires reducing this ratio to match that of the main gas path. The current work proposes a novel flow control solution to successfully achieve this purpose through the emerging technology of additive manufacturing. The successful flow control concept was developed through numerical simulation, printed using an additive manufacturing process, and validated in a purpose-built rig. Experiments and computations were consistent with a cumulative reduction in cavity windage of 16%. The FCC is estimated to increase the mechanical efficiency of the turbine stage in isolation by 1%.
Overall Cooling Effectiveness of Effusion Cooled and Thermal Barrier Coated Swirl Stabilized Liquid Fueled Combustor Liner in Reacting Flow Conditions With Infrared Thermography
Authors: Tin Ibrahim Edhem , Ural Muhammed Emin , Ozogul Hamdullah 
Published: August 2024

Abstract
Effusion cooling and thermal barrier coating have a crucial ability to cool down modern combustor liners and keep metal temperature below material maximum service temperature. Therefore this method has enabled high combustion temperature, which leads to powerful and more efficient gas turbine engines over the last decades. Effusion cooling method is obtained by arrays of holes settled all over a combustor liner to generate a uniform film layer at the hot gas side. Coupling of effusion cooling and thermal barrier coating provides high cooling effectiveness and low amount of coolant demand.
In this paper, experimental results of an effusion cooled and thermal barrier coated (TBC) combustion liner are presented. The rig was liquid fueled and swirl stabilized, in order to generate engine like reacting conditions. In this study, the overall cooling effectiveness of the liner has been examined under rich fuel conditions in different coolant-to-main air ratios. The combustion liner of a can combustor was laser drilled to provide 25 degrees inclined holes for an effective effusion cooling scheme. Thermal Barrier Coating has been applied equal to 40% off metal thickness of the liner. The effusion cooling scheme has been formed to have dense staggered array with s/d = 9. Infrared Thermography (IRT) was employed to measure the liner metal temperature and overall cooling effectiveness values were identified.
Noise Source Identification for the Unsteady Low Pressure Turbine Flow Fields
Authors: Yan Lanyi , Simoni Daniele , Luan Yigang , Sun Tao , Barsi Dario , Zunino Pietro 
Published: August 2024

Abstract
The paper presents a data processing methodology to identify the noise sources in low pressure turbine stages and their relative importance. Scale adaptive simulation (SAS) has been carried out on a geometry reproducing the midspan blade section of an entire LPT stage. The proper orthogonal decomposition (POD) is applied to data matrices constructed with the velocity and the pressure fields in order to distinctly extract the coherent structures responsible for velocity fluctuations and pressure waves (i.e. POD modes from the corresponding kernel), their temporal evolution and energies. The cross-correlation matrices of the pressure modes and the velocity modes reveal the degree of coupling between pressure and velocity oscillations, thus highlighting the modes linked to the same flow phenomena. The results show that the periodic vortex shedding at the stator trailing edge emits strong pressure waves, and the upstream propagating waves reflect against the adjacent stator suction surface. The POD modes related to the rotor-stator interaction show peak amplitudes at the blade passing frequency and its harmonics and their shapes mimic the potential interaction in the stator domain and the migration of viscous wakes in the rotor domain. The POD modes with lower energy content correspond to the stochastic turbulent structures originated from the turbulent boundary layers as well as those carried by the vane and blade wakes. The biggest noise sources of the current flow fields are identified to be the von Karman vortex street downstream the stator trailing edge and the rotorstator interaction.
The Effect of Air-Water Mixture on the Dynamic Response of a Hydrodynamic Journal Bearing With Inclined Grooves
Authors: Voitus Anthony , Arghir Mihai , Hassini Mohamed-Amine 
Published: August 2024

Abstract
Water lubricated hydrodynamic journal bearings with deep inclined grooves are often used to support radial loads and dampen pump vibrations in nuclear power plants. The inclined grooves increase the pumping effect of the lubricant thus reducing wear and friction during rotor start-up and coast-down. The deep grooves also facilitate the removal of debris without damaging the bearing. The load capacity and the stability of this type of bearing is studied in the present work. A sensitivity study of the impact of the number of grooves on bearing performance underlined the superiority of the journal bearing with two inclined grooves. Moreover, these journal bearings may operate with a mixture of water and air. This compressible two-phase lubricant will modify the load capacity and the stability of the journal bearing. The impact of the ingested volume fraction of air is therefore investigated. A physical model of the homogeneous air-water mixture linking the local air volume fraction with the pressure was used in conjunction with the numerical solution of the compressible Reynolds equation on an unstructured grid. It was found that the air ingestion in the 2-inclined grooves journal bearing decreases the load capacity but improves the stability for mild and low loads.
Preliminary Vibro-Acoustic Investigation of an Oil-Free Centrifugal Compressor
Authors: Krishna Karthik , Mendonca Fagundes Tadeu , Yan Jin , Richman Brenden , Dingman Ryan 
Published: August 2024

Abstract
The demand for HVAC chiller systems in commercial centers is ever-increasing. Chillers with centrifugal compressor units produce high-frequency noise, a significant problem that needs to be addressed. The blade passing frequency is the primary noise source a centrifugal compressor generates. The objective of this paper is to investigate the vibro-acoustic performance of an oil-free two-stage centrifugal compressor with magnetic bearings via numerical modeling. The noise source is obtained using the time-variant pressure data from the unsteady RANS simulation of the aerodynamic parts of the compressor. The unsteady pressure data produced is integrated onto the corresponding solid domain of the compressor, and a harmonic response analysis is carried out to quantify the vibration energy transferred through the compressor system at specific engine orders. Finally, the far-field sound pressure level generated by the compressor is quantified for all engine orders up to 10kHz. Additionally, experimental testing of the centrifugal compressor in a anechoic chamber is carried out to determine the sound pressure level and validate the numerical methodology. Results indicate that numerical findings are in good agreement with the test data, indicating that the developed methodology is capable of accurately predicting the tonal noise in the current application. Furthermore, results show the tonal noise generated is primarily dependent on the number of main blades and splitter blades of the impeller, revealing those components to be the primary source of compressor noise.
Experimental and Analytical Investigation of Labyrinth Seal Packing Ring Behavior in Contact With a Whirling Rotor
Authors: Tsukuda Tomohiko , Iwasaki Yoshifumi , Iwai Shogo , Tashima Tsuguhisa 
Published: August 2024

Abstract
Labyrinth seal packing ring behavior in case of contact with a whirling rotor which simulates the expected rotor vibration in an actual steam turbine was investigated experimentally and analytically. The labyrinth seal packing ring used in this study was designed to be supported to a casing with weak coil springs. The force of the coil springs is set to be slightly larger than the packing ring weight so that it escapes away from the rotor in case of contact with a rotor and the temperature rise of the rotor could be prevented.
Experimental investigation with a seal test rig was conducted with two different types of split structures of the packing ring. The effect of the split structure on the packing ring behavior and the rotor temperature rise in case of contact with a whirling rotor was investigated. The experimental results showed that the temperature rise of the rotor was smaller for the 3-split structure than the 2-split structure in case of contact with a whirling rotor. It also showed the amplitude and the dominant frequency of the vibration of the packing ring segment was different between the 3-split structure and the 2-split structure.
Analytical investigation using motion equations of a rigid body was carried out to understand the packing ring behavior. The difference of the segment behavior between the 2-split structure and the 3-split structure was explained by the solutions obtained from the motion equations. The difference of temperature rise of a rotor between the 2-split structure and the 3-split structure was discussed by simple evaluation of heat generation using the solutions of the equations.
Micro-PIV Investigation of Near-Critical and Liquid CO2 Conditions Inside a T-Channel Setup
Authors: Ghorpade Ritesh , Kim Gihun , Niazi Soroush , Peles Yoav , Vasu Subith 
Published: August 2024

Abstract
Supercritical CO2 (sCO2) has been proposed for a plethora of applications, such as power generation, air conditioning, and thermal management of electronic equipment. In proximity to critical conditions, the thermal and transport properties of the CO2 vary abruptly, promoting a significant heat transfer enhancement. Revealing the heat transfer processes associated with CO2 flows requires measuring fluid temperature, pressure, heat transfer coefficients, velocities, etc. However, fundamental knowledge about the heat transfer processes at near-critical conditions is not fully understood. An advanced optical technique with microparticle image velocimetry (PIV) was applied to measure the velocity flow field of liquid CO2 near critical thermodynamic conditions flowing through a T -channel. The captured flow field of the CO2 was processed using a micro-PIV 2D2C (Two Directional Two Component) cross-correlation method for obtaining the velocity vectors. Silver-coated hollow glass microspheres with a range of diameters of 5 microns to 30 microns were used as a tracer and mixed with CO2 to track the flow patterns. The experimental setup consists of the integrated manifold for CO2 flow, RTD probes for temperature measurements, digital pressure transducers for pressure measurements, and PIV arrangement with laser. The present experimental study is an initial step to fully reveal the velocity distribution of liquid CO2 inside a T-channel in near-critical thermodynamic conditions.
Improving Micro-Mixing Combustion Stability Using Fuel Preheating and Product Recirculation
Authors: Landry-Blais Alexandre , Bellavance Xavier , Dehue Mathilde , Plante Jean-Sébastien , Picard Mathieu 
Published: August 2024

Abstract
Micro-mixing is a promising combustion approach due to its inherent safety against flashback and autoignition, with multiple studies having demonstrated low NOx levels in the order of premixed combustion. Previous work has extended the operating limits of micro-mixing combustion to the design requirements of highly recuperated gas turbines, demonstrating low NOx performance at inlet temperatures of up to ∼1000 K with hydrogen and hydrocarbon-based fuels such as propane, natural gas, and jet fuel. Due to its highly reactive nature, micro-mixing combustion of hydrogen is very stable, but instabilities were observed with hydrocarbon-based fuels when operating near premixed levels of NOx due to their slower reaction rates, indicating that a trade-off exists between NOx emissions and combustion stability. This paper presents the experimental results of a new micro-mixing injector designed to improve combustion stability by 1) increasing the recirculation of combustion products to the flame zone, and 2) preheating the fuel by heat transfer from the combustion products to the injector. Although this configuration is still susceptible to instabilities, their amplitudes are much lower, with levels of &lt; 10 dB compared to ∼20 dB for the standard micro-mixing injector. NOx emissions are similar for both injector configurations, indicating a better trade-off between combustion stability and emissions when operating near the levels of perfectly premixed combustion for the new injector configuration.
Understanding the Flow Field in a Highly Loaded Tandem Compressor Cascade
Authors: Tran Thanh-Son , Babin Cedric , Fontaneto Fabrizio , Coussement Gregory , Verstraete Tom 
Published: August 2024

Abstract
Large flow turning in compressor cascades with single airfoils requires an effective control of the boundary layer growth under the diffusing flow. An alternative approach consists of distributing the loading over two subsequent airfoils, using a so-called tandem blade, to, in some measure, restart the boundary layer before flow separation occurs. It is, however, not always clear whether the benefits of the two-blade setup justify the additional manufacturing complexity. The present work explores the tandem blade concept using a gradient-based optimization method to produce an efficient, highly loaded compressor cascade blade directly. A comparison between two-dimensional single and tandem configurations is first presented to clarify the benefits of one over the other. The geometry is optimized for each concept using a gradient-based optimization technique to improve the pressure loss coefficient at multiple operating points for a given flow-turning constraint. While the optimized single and tandem blade designs have similar performance, the lower solidity of the latter provides a lighter compressor stage for the considered operating range. A three-dimensional tandem compressor cascade based on the two-dimensional study is then optimized to account for secondary flows. The aerodynamic performance and the operating range are assessed and compared, along with a study of the physical phenomena surrounding the tandem configuration. The resulting geometry presents similar non-conventional features observed during the two-dimensional study that exploits the flow mechanism of two-airfoil configurations.