Mixing Region Research Articles

Large eddy simulation on effects of trench geometry on film cooling effectiveness through fan-shaped holes

Modern gas turbines require the use of external film-cooling techniques to effectively cool the turbine blades, which are heated by hot combustion gases. Large eddy simulation (LES) is conducted to numerically evaluate the influences of trench configurations on film-cooling effectiveness and flow-field behavior of a shaped hole. The cooling hole was a laidback fan-shaped hole with a 17.5-degree forward expansion angle located on a flat plate surface with a 30-degree injection angle at a constant blowing ratio of 2.0 and a constant density ratio of 1.5. The computed film-cooling effectiveness was validated with that obtained in the experimental data for the reference case at two blowing ratios. Two geometrical parameters of the trench height and width were selected as design variables, and overall area-averaged film-cooling effectiveness was considered as an objective function. The Latin Hypercube sampling (LHS) method was applied to generate the designed cases and two different optimization algorithms, the response surface methodology (RSM) and the Kriging method, were employed to maximize the objective function. The computational LES results revealed that trenched cases with a larger trench height and a relatively smaller trench width improved cooling performance. The optimal trench configurations based on the RSM and Kriging method, demonstrated improvements in cooling performance by 27% and 25%, respectively, compared to the reference case without a trench slot. The transient analysis also showed that the flow unsteadiness and velocity disturbances near the trench exit at the mixing region were weakened for the cooling holes with the optimal trench cases.

Use of positron emission particle tracking to assess mixing of a graphite-based lithium-ion anode slurry in an Eirich mixer

The mixing of electrode slurries is a key processing step during the manufacturing of lithium-ion batteries, and poor mixing can have a profound effect on final cell electrochemical performance. This is complicated by the evolving non-Newtonian rheology of these slurries. In this study, Positron Emission Particle Tracking (PEPT) is used to determine the fluid dynamics and dispersion of a model graphite-based anode slurry in an Eirich EL1 mixer, equipped with a rotating pan, wall scraper and internal rotor. The main processes studied are the wetting of graphite particles and breakup of large graphite agglomerates. For experiments performed at different internal rotor tip speeds, with fixed outer pan speed, the dispersion dynamics change with the lowest rotor speed (2 m/s) leaving a large channel of poor mixing between the rotor region and the rotating pan, whilst the mixing within the vessel is mainly driven by the rotating pan. At higher mixing speeds (6 and 10 m/s) more of the vessel volume is active and there is no longer a poor mixing region observed, with 10 m/s tip speed producing the highest intensity of dispersion. An increasing mixer effectiveness (average dispersion across the mixing vessel) as well as an increasing dispersion co-efficient (rate of mixing) is also observed, which will be use to inform scale-up criteria.

Numerical study on spray characteristics of liquid jets in supersonic crossflow

The spray characteristics of liquid jets in supersonic crossflow at different injection jet-gas momentum ratios are investigated numerically. The compressible two-phase flow large eddy simulation (LES) method is based on the Eulerian-Lagrangian scheme. The average droplet volume fraction is defined to quantify spray concentration distribution, which can also reflect the oscillation boundary of the spray. The LES predicted the spray boundaries at different injection jet-gas momentum ratios in the central and cross-sectional planes, which agree reasonably well with the experiment. Two sets of counter-rotating vortex pair (CVP) are in the gas-liquid mixing region. As injection momentum ratio q increases, the upper CVP increases. Still, the absolute size of the wall CVP remains almost unchanged, which means that the relative size of the wall CVP to the upper CVP becomes smaller. As q increases, the spray's overall distribution position is generally upward, and the number of droplets entering the near-wall region becomes small. Thus, droplet-wall interactions are weakened. The spray body increases with the increase of q, while the spray foot decreases gradually. In the central plane, the coherent structures near the wall are mainly composed of splashed droplets, and this phenomenon gradually weakens as q increases. Although the increase of q can increase the total droplet mass flow rate, the proportion of the droplet mass flow rate in the near-wall region to the total mass flow rate decreases, and the droplet mass flow rate in the near-wall region decreases.

Effect of ion collision on separation between light and heavy ions in multi-component vacuum arc

In multi-component vacuum arc discharge, light ions and heavy ions usually have different spatial distributions of density and velocity. Previous research has suggested that the difference in spatial distribution of light and heavy ions is due to the mixing effect of cathode spot jet. However, in this work, the ion collision is found to be an important factor leading to the separation of light and heavy ions. In this paper, multi-fluid model is used to study the effect of ion collisions on separation mechanism in multi-component vacuum arc. The simulation results show that, during the jet mixing process, the collisions between different ions will reduce the velocity of light ions, and greatly increase the density and temperature. As a result, the pressure expansion of light ions is significantly enhanced. In addition, the collision between different ions will also increase the size of jet mixing region for light ions, which makes the plasma jet of light ions mixing more fully. These effects make their isotropic expansion dominant, and the ion density at the center is not much different from that at the edge. However for heavy ions, the collision between different ions has little influence on their movement. The pressure is far less than the inertia force, so the density of heavy ion mainly distributes along the convection direction, and the center is greater than the edge. This is the main separation mechanism of ion angular flux. It is also found there are three main factors leading to the separation of light and heavy ions: ion mass, ion density and ion temperature. The separation effect can be enhanced by increasing ion temperature, decreasing ion density and selecting electrode components with significant differences in elemental mass. This paper provides an insight into the mechanism of ion separation in multi-component vacuum arc.

Evolution of high-density submarine turbidity current and its interaction with a pair of parallel suspended pipes

The method of large-eddy simulation (LES) coupled with the density transport equation is employed to simulate the evolution of a gravity-driven high-density turbidity current and its interaction with a pair of parallel suspended pipes. The LES method is validated first using data of a non-Boussinesq lock-exchange experiment and satisfying agreement between LES and experiment is achieved. The simulations reveal that a shear region forms between high- and low-density fluids each moving in opposite directions which lead to the generation of a series of vortices and a substantial mixing region. Close to the bottom boundary, low-density fluid is entrained near the head of the high-density turbidity current, forming a thin water cushion that separates the turbidity current's head from the seabed, the so-called hydroplaning effect, thereby reducing the density of the head and bottom friction. The current study suggests that the effect of hydroplaning phenomena leads to high speed and long distance of the turbidity current. Further, LES simulations of a turbidity current impacting a pair of parallel suspended pipes with different streamwise spacings are performed and impact forces are quantified. The turbulent wake generated by high-density fluid bypassing pipe 1 promotes velocity fluctuations leading to increased impact forces on pipe 2 with increasing streamwise spacing up to 8 times the pipeline diameter (8D). The results suggest that the streamwise spacing between two parallel pipes should be less than 2D to minimize hydrodynamic loads on pipe 2.

The investigation of hydrogen released on the mixed jets with an axisymmetric jet and an asymmetric jet

Hydrogen released from complex multi-pipeline leakage sources can increase the difficulty of predicting the risk region of hydrogen and the probability of explosion accident. To investigate the collision and mixing features of subsonic hydrogen jets released from multi-pipeline leakage sources, an experimental platform for gas visualization and quantitative measurement is constructed. The differences in flow field structure and concentration distribution of vertical axisymmetric hydrogen jet, vertical asymmetric hydrogen jet and mixed hydrogen jets are compared and analyzed. Furthermore, the effects of multiple factors on the jet centerline, concentration decay, hazardous volume and diffusion height of the mixed region are predicted. The numerical simulation results are verified by the experimental data. Results indicate that the asymmetric hydrogen jet causes the mixed region centerline of hydrogen to deviate from the vertical axis under the combined effect of momentum-dominant and buoyancy. With the increase of the volumetric flow rate, the slope of the mixed region centerline initially decreases and then increases, with the smallest slope occurring at a volumetric flow rate of 159 NL/min. Either the increase of the leakage orifice diameter or the decrease of the distance between two leakage orifices can cause the slope of the mixed region centerline to decrease. Among three factors, the leakage orifice diameter has the most obvious effect on the concentration decay. The hydrogen diffusion height gets the highest when the ratio of leakage orifice diameter to pipeline inner diameter is 0.4 among five leakage orifice diameters. The distance between two leakage orifice has no significant influence on the hazardous volume. The investigation provides valuable data to support the prediction of the dangerous range of hydrogen leakage in complex multi-pipeline leakage sources.

Foot and Ankle Forklift Injuries; Diagnosis to Treatment Options, Return to Work and Functional Outcomes

As our tertiary-level trauma center is close to an industrial zone and associated international port, industrial injuries are seen more often than is expected in routine practice. The aim of this study was to present the demographic data, treatment options, and changes in work-life of patients with foot and ankle injuries due to a forklift accident, and to determine the factors affecting the clinical outcome. The study was conducted in our university hospital and included patients who presented with a foot and ankle injury resulting from a forklift accident. Data were collected including age, sex, dominant extremity, history of trauma, presence of fracture, management (surgical or conservative), complications, time of return to work, workforce loss, and the American Orthopaedic Foot and Ankle Society (AOFAS) and Short Form Health Survey (SF-36) scores at the final follow-up examination. Evaluation was made of 132 patients, comprising 113 (85.6%) males and 19 (14.4%) females with a mean age of 32 years (range 16-65 years). The most frequently recorded occupational group was shipyard workers (50%). The most common mechanism of injury was crushing under the forklift wheel (n = 63, 47.7%). The most frequently injured foot region was the forefoot (47%). A total of 90 (68.1%) patients continued to work in the same position on return to work. The lowest mean AOFAS score (73.4) and SF-36 (physical component) score (37.3) were determined in cases with mixed region injuries (p = .0001, p = .0001). The wearing of protective footwear had no effect on the rate of return to work (p = .195), workforce loss (p = .34) and AOFAS score (p = .166). This study is the largest series of patients with foot and ankle injuries related to forklift accidents. Forklift injuries can be treated conservatively or surgically according to the clinical condition of the patient. The main indicators of return to work and functional outcome are which foot region is injured and whether or not the injury causes a fracture.

Canopy-Height and Stand-Age Estimation in Northeast China at Sub-Compartment Level Using Multi-Resource Remote Sensing Data

Stand age is a significant factor when investigating forest resource management. How to obtain age data at a sub-compartment level on a large regional scale conveniently and in real time has become an urgent scientific challenge in forestry research. In this study, we established two strategies for stand-age estimation at sub-compartment and pixel levels, specifically object-based and pixel-based approaches. First, the relationship between canopy height and stand age was established based on field measurement data, which was achieved at the Mao’er Mountain Experimental Forest Farm in 2020 and 2021. The stand age was estimated using the relationship between the canopy height, the stand age, and the canopy-height map, which was generated from multi-resource remote sensing data. The results showed that the validation accuracy of the object-based estimation results of the stand age and the canopy height was better than that of the pixel-based estimation results, with a root mean squared error (RMSE) increase of 40.17% and 33.47%, respectively. Then, the estimated stand age was divided into different age classes and compared with the forest inventory data (FID). As a comparison, the object-based estimation results had better consistency with the FID in the region of the broad-leaved forests and the coniferous forests. In addition, the pixel-based estimation results had better accuracy in the mixed forest regions. This study provided a reference for estimating stand age and met the requirements for stand-age data at the pixel and sub-compartment levels for studies involving different forestry applications.

Numerical analysis on the transom-stern wake with a horizontal plunging jet

The turbulent flow behind a dry-transom stern with a plunging water jet is numerically studied. High-resolution large eddy simulation (LES) is performed to predict the wave-elevation topology and vortex structure in the wake with varying jet height. The theoretical impact position between jet flow and stern wave is proposed. The turbulent wake under the stern-jet configuration can be divided as converging-corner-wave region (CCW), mixing region (MR), transition region (TR) and developed region (DR). High-speed plunging jet speeds up the averaged-axial velocity and enhances the shear effect near the free surface. The upward movement of the rooster tail is suppressed by the parabolic jet flow, and periodical large scale air pockets are clearly observed following the wake angle along the downstream direction. Air pocket vortices and jet vortices are merging in the near wake and forming U-shaped vortex structures. Reducing jet height accelerates the instability of coherent vortex structure and energy dissipation in the developed region. The main contributions in the power spectra density (PSD) spectrum of Turbulent Kinetic Energy appear in the frequency range of 10–20 Hz with the evolution of wake vortices.

Barotropic and baroclinic tides increase primary production on the Northwest European Shelf

High biological productivity and the efficient export of carbon-enriched subsurface waters to the open ocean via the continental shelf pump mechanism make mid-latitude continental shelves like the northwest European shelf (NWES) significant sinks for atmospheric CO2. Tidal forcing, as one of the regionally dominant physical forcing mechanisms, regulates the mixing-stratification status of the water column that acts as a major control for biological productivity on the NWES. Because of the complexity of the shelf system and the spatial heterogeneity of tidal impacts, there still are large knowledge gaps on the role of tides for the magnitude and variability of biological carbon fixation on the NWES. In our study, we utilize the flexible cross-scale modeling capabilities of the novel coupled hydrodynamic–biogeochemical modeling system SCHISM–ECOSMO to quantify the tidal impacts on primary production on the NWES. We assess the impact of both the barotropic tide and the kilometrical-scale internal tide field explicitly resolved in this study by comparing simulated hindcasts with and without tidal forcing. Our results suggest that tidal forcing increases biological productivity on the NWES and that around 16% (14.47 Mt C) of annual mean primary production on the shelf is related to tidal forcing. Vertical mixing of nutrients by the barotropic tide particularly invigorates primary production in tidal frontal regions, whereas resuspension and mixing of particulate organic matter by tides locally hinders primary production in shallow permanently mixed regions. The tidal impact on primary production is generally low in deep central and outer shelf areas except for the southwestern Celtic Sea, where tidal forcing substantially increases annual mean primary production by 25% (1.53 Mt C). Tide-generated vertical mixing of nutrients across the pycnocline, largely attributed to the internal tide field, explains one-fifth of the tidal response of summer NPP in the southwestern Celtic Sea. Our results therefore suggest that the tidal NPP response in the southwestern Celtic Sea is caused by a combination of processes likely including tide-induced lateral on-shelf transport of nutrients. The tidally enhanced turbulent mixing of nutrients fuels new production in the seasonally stratified parts of the NWES, which may impact the air–sea CO2 exchange on the shelf.

Effects of uniaxial stress and temperature on the interfacial tensile strength and stability of Al/NiO nanolaminates: A first-principles study

Nanoenergetic multilayer films have been widely prepared due to their unique advantages in realizing “nanoenergetics-on-a-chip”. Recently, the potential for adjusting the performance of nanothermites without altering their film thickness has attracted much attention, prompting researchers to concentrate on film stress. Here, we employed first-principles tensile tests and ab initio molecular dynamics simulations to investigate the tensile properties, fracture mechanisms, and film stability of two Al/NiO interfaces under pre-stress. An analysis of electron localization function and bond overlap population shows that the weakest locations of the (100)-Top and (111)-Top interface systems are distinctly different, leading to two different fracture mechanisms. When the pre-stress and temperature are coupled, the reactivity of Al/NiO as an energetic material is enhanced. Particularly for (111)-Top, the amorphous, mixed region between the two phases replaces the original coherent interface. With the increase of the pre-stress, the crack evolves ahead of the critical strain, indicating that the coupling effects of the pre-stress and temperature have an important influence on the stability and fracture strength. This work not only reveals the mechanical properties of Al/NiO, but also provides a theoretical guidance for optimizing the structure of energetic nanolaminates.

Prediction of transonic film cooling using the turbulent viscosity correction method

Two-equation turbulence models, such as the k–epsilon (k–ε) and shear stress transport (SST) models, have limited accuracy in calculating film cooling effectiveness. Previous studies have focused on modifying the turbulent Prandtl number from the perspective of thermal diffusion to improve the prediction accuracy of film cooling simulations. However, the flow accuracy of the jet flow is crucial for simulating film cooling. The calculated film cooling effectiveness differs from the experimental results due to deviations in the predicted amount of mixing. This study proposes corrections to the baseline k–ω model developed by Menter. The proposed method modifies the flow field with the mass species conservation equation in the mixing region while maintaining the advantages of the original model in the nonmixing region. The principle of the corrected model is explained through comparison and analysis with the SST model. The corrected model significantly improves the mixing effect of the two fluids. The main principle behind this is that the corrected model more accurately predicts turbulence intensity in the mixing zone of the two fluids. Furthermore, this paper experimentally validates the modified model for an array of film holes with Mach numbers of 0.4 and 1.4. The proposed model shows a 24% improvement in computational accuracy compared to the SST model.

A Computational Examination of Side-by-Side Rotors in Ground Effect

This study investigates the interactional aerodynamics of hovering side-by-side rotors in ground effect. The 5.5-ft diameter, three-bladed fixed-pitched rotors are simulated using computational fluid dynamics at a targeted 5 lb/ft2 disk loading. Simulations are performed using the commercial Navier–Stokes solver, AcuSolve ®, with a delayed detached eddy simulation model. Side-by-side rotors are simulated at two heights above the ground (H/D = 0.5 and H/D = 1), and with two hub–hub separation distances (3R and 2.5R). The performance of side-by-side rotors in ground effect (IGE) is compared to isolated rotors out of ground effect. Between the side-by-side rotors IGE, a highly turbulent mixing region is identified where the wakes of each rotor collide. The flow fountains upwards, as well as exits outwards (along a direction normal to a plane connecting the two rotor hubs) with fountaining between the rotors reaching up to 0.75D above the ground. As blades at H/D = 0.5 traverse the highly turbulent flow, strong vibratory loading is induced and a thrust loss is observed over the outboard sections between the rotors that is large enough to negate any nominal ground effect benefits inboard. Side-by-side rotors at H/D = 0.5 with 2.5R hub–hub spacing produce peak-to-peak thrust oscillations up to 16% of the steady thrust. Rotors placed higher, at H/D = 1 are positioned above the turbulent mixing flow and produce significantly lower vibratory loads. The spacing between rotors at H/D = 0.5 and 3R hub–hub separation allows strong vortical structures to develop between the rotors which move from side to side over multiple revolutions. When the vorticity moves closer to one of the rotors, it produces a greater lift deficit over the outboard region and a stronger vibratory loading. For rotors closer together, at H/D = 0.5 and 2.5R separation, the vortical structures between rotors are constrained to a more concentrated area and show less side-to-side drift.

Влияние биогумуса на основе отходов птицеводства на физико-химические свойства дерново-подзолистых почв и выращиваемых растений

Introduction. The current phase of mass production in the poultry products sector creates large volumes of waste in the form of chicken manure. This waste contributes to the negative environmental impact on the neighboring territories. To address the issue of storing chicken manure, several methods have been developed, of which incomplete combustion and composting with gradual decay are two major ones. The application of both technologies results in the production of fertilizers such as mineral biochar and organic humus. The role of these fertilizers is particularly important for regions that face the challenge of insufficient fertility of the zonal soil type, a concern that is common in some mountainous regions. The goal of the study is to develop a method and analyze the results of its application to successfully solve the problem of excess chicken manure by producing a substance that improves the physicochemical properties of sod-podzolic soils and increases their biological efficiency. Materials and methods. The laboratory facilities of the Ecosystem Research Center at St. Petersburg Mining University were used in this study. The physicochemical properties of soils and plants were analyzed based on a standard method for determining the organic content of soils using gravimetric, thermogravimetric, and optical emission spectrometry methods. Results and discussion. Given the relatively low fertility of sod-podzolic soils, which are common in mixed forest regions, the article proposes a modified version of composting as a priority for processing poultry manure. This method accelerates the biochemical processes of manure decay by using a specially bred subspecies of the earthworm Eisenia fetida. The article provides a detailed description of this method for processing poultry manure, which results in the production of an organic fertilizer. To evaluate the effect of the biofertilizer produced by the proposed method on the physicochemical properties of sod-podzolic soils and the plants grown on them, we conducted an experiment involving the addition of the biofertilizer to the soil, followed by sowing ryegrass and spring onion seeds, followed by an analysis of soil and plant samples. The results of the experiment showed that the presence of the biofertilizer in the soil increases its moisture content, improves moisture retention, and reduces ash content. The addition of the biofertilizer significantly increases the contents of humus, organic carbon, total nitrogen, phosphorus, and potassium, also promoting the removal of heavy metals. The use of the proposed biofertilizer enhances the uptake of carbon, nitrogen, and potassium into plants. The proposed method is adapted to residential area conditions and can be used by agricultural companies in various regions of Russia. A future line of research includes experiments to find the rational biofertilizer application rates for growing more common vegetable and grain crops in soils of different types. Conclusions. The study has developed a comprehensive method for investigating the processes of transfer of organic matter and chemical elements from the proposed biofertilizer into soils and plants. This method includes laboratory tests of the physicochemical properties of soils before and after the experiment and those of fertilizers and plants after the experiment. The results demonstrate that the presence of the biofertilizer in dry sod-podzolic soils increases their fertility and improves the physicochemical properties of both the soils and the plants. Resume. The proposed method is adapted to residential area conditions and can be used by agricultural companies in various regions of Russia. A future line of research includes experiments to find the rational biofertilizer application rates for growing more common vegetable and grain crops in soils of different types.

ON THE POSSIBILITY OF INITIALIZATION OF SYNTHESIS IN SMALL-SIZED INSTALLATIONS WITH QUADRUPOLE MAGNETIC SYSTEMS WITH SPHERICAL СUMULATION OF SHOCK MAGNETIC WAVES IN THE BLANKET CONFIGURATION OF PLASMA DISCRETS

The article presents an overview of models for solving the problem of controlled nuclear fusion, including in small-sized installations, methods and technology for obtaining and forming electronically controlled plasma and ion flows in a magnetic field. The sizes of such an installation in the pilot version are up to 1.5 meters long, due to the grouping of flows by sampling with a frequency of about 1 kHz achievable for materials today, multi-passability in the synthesis chamber, in traps and setting the laws of following with feedback for ion flows in plasma layers in magnetic field systems with the large gradient. The shock wave causes rapid heating of the convection mixing region, triggering a process of constant energy exchange between the heated mixture 11B-9Be and the lithium shell and, passing through the layer 11B-9Be, reaches the geometric center of the magnetic trap, where a small spherical cavity will be maintained, necessary for unlimited spherical cumulation on the cavity. This leads to a rapid increase in temperature and pressure in the area of collapse of the bubble, and makes it possible to increase the temperature to 108 K, which allows the launch of fusion reactions.

Near-surface damage and mixing in Si-Cl2-Ar atomic layer etching processes: Insights from molecular dynamics simulations

Silicon-chlorine-argon (Si-Cl2-Ar) atomic layer etching (ALE) is simulated using classical molecular dynamics (MD). The simulations provide a detailed view into the near-surface region during ALE processing. Bombardment of Ar+ ions creates a mixed amorphous region that significantly differs from the picture of ideal ALE. There is also a significant change in the Si etch yield and the etch product distribution as a function of Ar+ ion fluence. The Si etch yield is the highest at the beginning of the bombardment step but eventually decays to the physical sputtering yield. Atomic Cl and silicon chlorides are major etch products at the start of an ion bombardment step, but quickly decay. Atomic Si yields remain relatively constant as a function of Ar+ ion fluence. A new schematic of Si-Cl2-Ar ALE is presented in order to emphasize the complex behavior observed in MD simulations.

Recovery of dry mixed grass prairie well sites 15 years after reclamation

In the mixed grass prairie region of North America, well sites and their associated infrastructure have many ecological effects, including changes to soil physical, chemical and biological properties, loss of vegetation cover, altered plant species composition and habitat fragmentation. Reclamation of disturbed grassland is a challenge faced by many rangeland and conservation managers. The objective of this research was to examine the effect of time on reclaimed grassland well site soil properties and plant communities in southern Alberta. Seeding with three mixes of different numbers of species and proportions of native wheatgrasses (Triticeae tribe) was compared to natural recovery and undisturbed prairie after 15 years. Chernozemic soil was more similar to undisturbed prairie than Solonetzic soil, where soil chemical properties and plant species composition were less resilient following disturbance in some revegetation treatments. All reclaimed treatments had significantly lower soil organic matter, organic carbon and total nitrogen than undisturbed prairie. Vegetation cover and species richness in reclaimed sites did not usually differ from undisturbed prairie. An increase in the proportion of native wheatgrass cultivars in a seed mix did not result in a community dominated by them. Multivariate analysis showed species compositional differences in seeded and natural recovery relative to undisturbed prairie on Solonetzic soil, with no difference on Chernozemic soil except with the dominant wheatgrass seed mix. Thus recovery may require longer than 15 years for Solonetzic soil and revegetation with a dominant wheatgrass seed mix. Presence of early to late successional species indicated natural recovery could be a potential option for mixed grass prairie well site reclamation.

Experimental and unsteady numerical investigations on cooling characteristics of trailing-edge cutback with effect of upstream film holes

This paper investigates the influence of film cooling characteristics of pressure-side film hole on trailing-edge cutback in the high-pressure vane of gas turbines. This paper employs the Pressure Sensitive Paint (PSP) technique and Particle Image Velocimetry (PIV) technique to obtain the time-averaged adiabatic film cooling effectiveness and details of the mixing region, respectively. Numerical simulations with the DDES turbulence model are also used to predict the flowfields. Two configurations are examined: one with a cutback without pressure-side film holes (Config A) and another with a cutback that includes pressure-side film holes (Config B). This paper investigates eight blowing ratios (Mslot = 0.3–1.2) of slot coolant in cutback for Config A and a suitable blowing ratio (Mhole = 0.4) of film holes for Config B, using both experimental and numerical methods. The results of both experiments and simulations for Config A and B show good agreement and reveal a non-monotonic trend of film cooling effectiveness with increasing blowing ratio. The non-monotonic trend observed in Config A is attributed to an increase in the velocity gradient in the boundary layer on the coolant side with increasing blowing ratio, which leads to a different shedding vortex structure. The results for Config B show that the coolant from the pressure-side film holes changes the mixing structure downstream of the lip by rebuilding the mainstream's shear layer on the mainstream side. Adiabatic film cooling effectiveness increases significantly under low and moderate slot blowing ratios, but non-monotonicity is maintained. The Fast Fourier Transform method is used to investigate the impact of the jet stream, which affects only the area downstream of the film holes, while other regions along the pitch-wise direction are less affected. This paper also attempts to combine the effectiveness empirical correlations of 2D slot and film holes using the superposition model to quantitatively analyze the deterioration of cooling effectiveness resulting from the mixing of coolant and mainstream.

Compact Stars in the vBag Model and Its f-Mode Oscillations

Electromagnetic (EM) observations and gravitational wave (GW) measurements enable us to determine the mass and radius of neutron stars (NSs) and their tidal deformability, respectively. These parameters offer valuable insights into the properties of dense matter in NSs. In this study, the vector-interaction-enhanced bag model (vBag model) is employed to investigate strange and hybrid stars’ properties. The parameters of the vBag model are constrained using multi-messenger observations, revealing that strange stars are incompatible with current observations. In contrast, hybrid stars can exhibit a substantial mixed phase region and a thin hadronic shell. Furthermore, we present the frequencies and damping time of fundamental mode (f-mode) oscillations of hybrid stars and test their universal relations with compactness and tidal deformability. The findings indicate that the presence of mixed phase components leads to larger frequencies and shorter damping time of the f-mode oscillation of hybrid stars, and the softer equation of state (EoS) affects this behavior more significantly. The universal relations of hybrid stars in the vBag model can be described by fourth-order/seventh-order polynomials, which do not break the previous results.

Key Factors in Enhancing Pseudocapacitive Properties of PANI-InOx Hybrid Thin Films Prepared by Sequential Infiltration Synthesis.

Sequential infiltration synthesis (SIS) is an emerging vapor-phase synthetic route for the preparation of organic-inorganic composites. Previously, we investigated the potential of polyaniline (PANI)-InOx composite thin films prepared using SIS for application in electrochemical energy storage. In this study, we investigated the effects of the number of InOx SIS cycles on the chemical and electrochemical properties of PANI-InOx thin films via combined characterization using X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and cyclic voltammetry. The area-specific capacitance values of PANI-InOx samples prepared with 10, 20, 50, and 100 SIS cycles were 1.1, 0.8, 1.4, and 0.96 mF/cm², respectively. Our result shows that the formation of an enlarged PANI-InOx mixed region directly exposed to the electrolyte is key to enhancing the pseudocapacitive properties of the composite films.