Liquid Depth Research Articles

Upgrade constructed wetlands wastewater quality by solar-driven photochemical quaternary treatments in raceway pond reactor at pilot plant scale.

This study explores the potential application of solar photochemical processes (SPPs) for simultaneous disinfection and decontamination of urban wastewater (UWW) when combined with constructed wetlands (CWs). Two SPPs based on the addition of low concentrations of hydrogen peroxide and peroxymonosulfate (PMS) were evaluated. SPPs were carried out at pilot plant scale using low-cost solar open photoreactors (Raceway Pond Reactor (RPR)) under natural sunlight. The performance of the SPPs was analyzed by monitoring naturally occurring bacteria (Escherichia coli, Enterococcus spp. and Salmonella spp.) and Contaminants of Emerging Concern (CECs), such as pharmaceutical products, pesticides, antibiotics and their metabolites, simultaneously. SPP best operating conditions were determined by testing a wide range of oxidant concentrations (0-5.9mM, 0-3.0mM) and liquid depths (5, 10 and 15cm) in the RPR. SPP treatment efficacy was tested on the actual inlet and outlet of the CW system, showing the high influence of their different physicochemical characteristics on the oxidants' performance. H2O2/solar SPP in the actual inlet of the CWs showed slightly higher inactivation kinetics when increasing H2O2 concentration at both water depths (5 and 10cm), while no significant CECs degradation rates were obtained. However, much higher efficacy was obtained with PMS/solar process attaining high bacteria inactivation under dark conditions and 79% CEC degradation at 3.0mM after only 10min of reaction time. SPPs assessment on the outlet of the CWs also showed better efficacy of the PMS as oxidant compared to the H2O2 for the simultaneous CECs removal (95% at 1.0mM of PMS, after only 5min of treatment) and bacteria inactivation (confirming the no-regrown after 24h). SPPs have demonstrated to be a low-cost and eco-sustainable polishing alternative to regenerate CW effluents complying with the actual European regulation on the minimum water quality requirements for reusing treated UWW in agriculture.

Model-based scenario analysis to support the operation of solar photo-Fenton plants.

Model-based tools applied to wastewater management have been identified as an emerging solution to address the associated challenges related to the optimization of the technologies, meeting more restricted water quality standards. Thus, for the first time, the demonstration of the solar photo-Fenton process for microcontaminant removal in the operating environment of a model-based tool is reported. This tool aids in determining the right cost-effective seasonal strategy for a 37-m2 demonstration-scale photoreactor operating in a rural wastewater treatment plant. It was developed using a model tuned adequately with experimental data obtained at lab scale and then validated in the solar photo-Fenton demonstration plant, proving its reliability, and enveloping a robust operation. Imidacloprid removal was the treatment target, and reagent concentrations were 0.1mM for ferric nitrilotriacetate and 0.73mM for hydrogen peroxide. According to the model-based tool, to attain the maximum treatment capacity, the best operating conditions were a liquid depth of 20-cm, and hydraulic residence time of 45 and 60-min in summer and winter, respectively, augmenting the treatment cost by 25% (0.49 €∙m-3 vs. 0.65 €∙m-3). This model-based tool allows the control and optimization of the technology to be improved, while promoting its attractiveness in the market.

Solar Sonophotocatalytic Hydrogen Recovery from Sulphide Wastewater

Sonolysis-assisted photocatalytic hydrogen recovery from sulphide wastewater was conducted using Carbon nanotube (CNT) deposited ZnS/Fe2O3 core-shell particles. The synthesized photocatalyst was characterized for XRD, UV-DRS, SEM, EDX, HRTEM, FTIR, PL and XPS. Effect of catalyst dosage, photolytic volume and sacrificial agent (SO32-) concentrations were conducted for maximum hydrogen production. After optimization studies, it is observed that the maximum amount of hydrogen yield was obtained with 0.2M concentrations of sacrificial agent, 0.05g/L of catalyst dosage and 150mL of liquid depth. The prepared photocatalyst is found to be stable up to 6 cycles. Sonophotocatalysis shows better performance than sonolysis and photocatalysis. 6250 μmol/h is the highest H2 yield recovered from the sulphide containing wastewater collected from the sewage treatment plant.

Effect of liquid flux on wetting behavior in slender trickle bed reactors: A particle-resolved direct numerical simulation study

Slender trickle beds play a crucial role in various industrial processes involving gas-liquid-solid systems. Understanding the wetting characteristics is vital for optimizing their performance and efficiency. In this study, we employ a particle-resolved Computational Fluid Dynamics approach combining the Volume of Fluid (VoF) method for gas-liquid interactions and a second-order implicit Immersed Boundary Method (IBM) for fluid-solid interactions. The particle wettability is modeled by imposing a contact angle boundary condition at the gas-liquid-solid interface. The impact of the liquid flux on the wetting patterns and the rate of liquid penetration depth within the slender trickle bed is studied. The results show two main mechanisms of penetration through the bed: gravitation and inertia driven. The penetration of the liquid in the bed is driven by gravity when the liquid flux is low and the inertia is diminished in the top of the bed. This results in enhanced wetting from the onset of the penetration. If the inertia is high (high liquid flux), the initial liquid penetration is fast and spreading in the bed only occurs after full penetration of the bed.

Analysis of the interfacial evolution characteristics of hollow droplet impact on a liquid pool

The impact dynamics of a hollow droplet on a liquid pool have significant implications across various industrial applications. This study employs numerical simulations to explore the dynamic evolution of the interface during the impact of a hollow droplet on a liquid pool. The investigation focuses on the effects of varying the hollow ratio Dr and liquid pool depth h* while maintaining a constant volume of liquid within the droplet shell. The findings reveal that both the hollow ratio Dr and pool depth h* critically influence the formation of ejecta + lamella, and vortex rings after the impact of a hollow droplet on a liquid pool. The confinement effect of the pool bottom can influence the evolution of the splashing, while the internal air in the hollow droplet can absorb a part of the impact energy during the collision. Specifically, at shallow pool depths, the interface primarily evolves into ejecta + lamella structures, whereas at greater pool depths, vortex ring formation is predominant. Furthermore, an increase in the hollow ratio leads to a reduction in the critical pool depth hc* at which the transition between these interfacial modes occurs. These findings indicate that, in practical applications involving the impact of hollow droplets on liquid pools, sufficient attention should be given to the pool depth. This enhances our understanding of the bottom pressure, droplet impact, and vortex formation, which is of significant relevance to related industrial technologies.

Coupling UVC254 nm-LED/H2O2 and Fenton processes for disinfection and contaminants of emerging concern removal in continuous mode for wastewater reclamation in accordance with EU 2020/741

A novel strategy based on the sequential combination of UVC254 nm-LED/H2O2 and the Fenton process at neutral pH in continuous flow mode for wastewater reclamation has been assessed. The concentration of Escherichia coli (E. coli) reached water class A according to the European Union (EU) Regulation 2020/741 (≤10 CFU/100 mL) and a 87 ± 2 % of the contaminants of emerging concern (CECs) load was removed, complying with the new proposal regarding Urban Wastewater Treatment (Directive COM (2022) 541). To reach these results, initially the municipal wastewater secondary effluent was kept under UVC254 nm-LED/H2O2 process with a hydraulic residence time (HRT) of 5 min, a liquid depth of 5-cm and 1.8 mmol L−1 of H2O2. In the sequence, addition of Fe2+ to the outside of the UVC254 nm-LED reactor was added to acquire the desired concentration of 1.8 mmol L−1 Fe2+ (Fenton process). To obtain the same disinfection and CECs degradation by only UVC254 nm-LED/H2O2 process, 45 min-HRT were necessary. These results show that the coupled processes are the best strategy, given the reduction in HRT (from 45 to 5 min) and total cost (from 1.79 to 0.54 € m−3). In addition, new research on the application at pilot scale will encourage to evaluate the long-term toxicity of the reclaimed wastewater and to identify the main transformation products of the most abundant CECs.

Design and performance evaluation of toroidal TLCDs in bidirectional seismic control of structures using a modified dynamic model

In this study, a modified dynamic model which distinguishes between liquid oscillation and sloshing in vertical columns is derived for toroidal tuned liquid column dampers (TLCDs). In the modified model of toroidal TLCDs, the primary sloshing mode within vertical columns is modeled as mass–spring-dashpot systems, whereas the oscillatory behavior of the liquid is analyzed employing the conventional theory of TLCDs. The accuracy of the modified dynamic model in capturing bidirectional liquid responses is verified by computational fluid dynamics (CFD)-based simulations. A large number of CFD-based simulations are performed to establish a ready-to-use suggested formula for a newly introduced parameter (which is related to the geometric configuration of liquid containers and the initial liquid depth) in the modified model. Subsequently, considering the maximum allowable liquid displacement in vertical columns, an optimized design approach for toroidal TLCDs installed in symmetric and asymmetric structures is illustrated. On the basis of the proposed optimization design method, the bidirectional vibration control effects of toroidal TLCDs are comprehensively analyzed under El Centro, Loma Prieta, Northridge, and Chi–Chi seismic excitations in both the time and frequency domains. The results demonstrate the effectiveness of toroidal TLCDs for bidirectional seismic control of structures.

Droplet impinging on sparse micropillar-arrayed non-wetting surfaces

Wettability of droplets and droplet impinging on sparse micropillar-arrayed polydimethylsiloxane (PDMS) surfaces were experimentally investigated. For droplets wetting on these surfaces, the contact line density model combining stability factor and droplet sagging depth was developed to predict whether the droplets were in the Wenzel or Cassie–Baxter wetting state. It was found that droplets on the sparser micropillar-arrayed PDMS surfaces were in the Wenzel wetting state, indicating that a complete rebound cannot happen for droplets impinging on these surfaces. For the case of droplets impinging on sparse micropillar-arrayed PDMS surfaces, it was found that there existed a range of impact velocity for bouncing droplets on the micropatterned surfaces with a solid fraction of 0.022. To predict the upper limit of impact velocity for bouncing droplets, a theoretical model considering the immersion depth of liquid into the micropillar structure was established to make the prediction, and the lower limit of impact velocity for bouncing droplets can be obtained by balancing kinetic energy with energy barrier due to contact angle hysteresis. In addition, the droplet maximum spreading parameter was fitted and found to follow the scale law of We1/4.

Experimental and numerical study on dynamic response of a photovoltaic support structural platform with a U-shaped tuned liquid column damper

A tuned liquid column damper (TLCD) is widely used in offshore structures as a passive energy dissipation device to reduce the harm of wind, wave, and current loads to the safety of offshore platforms. This investigation explores the dynamic response and interaction mechanism of a photovoltaic support structural platform (SSP) equipped with a TLCD by experimental and numerical analysis. The vibration mitigation performance of the TLCD under varying liquid depth ratios, external excitation frequencies, and amplitudes is systematically evaluated. The experiments focus on assessing the structural dynamic response and wall pressure to determine the vibration reduction efficiency of the TLCD for structures with fundamental frequencies more than 2 Hz. The experimental results indicate that the TLCD can reduce the structural response maximally near the natural frequency (2.52 Hz) of the structure, with vibration reduction effectiveness ranging from 42.0% to 85.1%. Additionally, one develops a two-way fluid-structure interaction (FSI) model to investigate further the impact of hydrodynamic pressure caused by sloshing inside the TLCD on the SSP motion response, which providing a more detailed explanation for the different phenomena observed in the experimental results.

Study on the spray characteristics of transverse jets with elliptical nozzles in supersonic crossflows using the volume of fluid–discrete phase model

The atomization characteristics of liquid jets injected transversely into a supersonic crossflow significantly affect the performance of scramjet engines. Existing research on this topic has mainly focused on circular nozzles, while the influence of nozzle geometry, particularly elliptical nozzles, has received relatively limited attention. Therefore, this study employs a numerical simulation method coupling the volume of fluid and discrete particle model to investigate the breakup and atomization characteristics of transverse liquid jets from elliptical nozzles with different aspect ratios under supersonic crossflow conditions, as well as the total pressure loss. The simulation model is validated against experimental data obtained from a pulse wind tunnel, including measurements of the liquid jet penetration depth and the Sauter mean diameter (SMD). The results indicate that for elliptical nozzles with an aspect ratio (AR) greater than 1, columnar breakup occurs earlier, and the columnar breakup length is shorter compared to circular nozzles. As the AR increases, the jet penetration depth decreases, while the spray expansion angle increases. Furthermore, the SMD of the atomized spray field from the circular nozzle is larger than that from the elliptical nozzles, and the SMD of the spray field is smallest for an elliptical nozzle with AR of 4. Finally, the elliptical nozzles exhibit a higher total pressure recovery coefficient, indicating reduced total pressure loss in the combustion chamber. This reduction in pressure loss is expected to improve the thrust performance of the scramjet engine.

Stock Market Liquidity and Stock Market Performance in Nigeria: Evidence from the Nigerian Exchange Limited

Insufficient liquidity can become a significant obstacle to stock trading and impede the smooth operation and performance of the stock market. This motivated the study to investigate the effect of stock market liquidity on stock market performance in Nigeria. The research design employed was ex post facto, while stratified sampling technique was used to select top 30 actively traded and most liquid companies tagged NGX-30 for this study. Data were sourced secondarily from SEC Statistical Bulletin, CBN Statistical Bulletin and www.investing.com. The Vector Error Correction (VEC) System Equation Regression was employed as the estimation technique. The results revealed that liquidity depth, liquidity breadth, and liquidity immediacy have significant positive effects on stock market performance as shown by ? = 0.2019, 8.5594, 3.3268; p-value = 0.0329, 0.0052, 0.0467 respectively. Also, interest rate, inflation rate and exchange rate have varied significant effects on stock market performance as shown by ? = -0.0023, -1.1738, 0.03432; p-value = 0.0634, 0.0346, 0.0778 respectively. Therefore, the study concluded that stock liquid significantly affects stock market performance. Thus, the study recommended that the Security and Exchange Commission (SEC) should implement policies that encourage the participation of more traders to increase the number of actively traded stocks; support measures that improve the depth of the market by promoting transparency and fairness; improve the infrastructure for trade execution to enhance liquidity immediacy; and develop mechanisms to promptly identify and mitigate market risks.

Metachrony drives effective mucociliary transport via a calcium-dependent mechanism.

The mucociliary transport apparatus is critical for maintaining lung health via the coordinated movement of cilia to clear mucus and particulates. A metachronal wave propagates across the epithelium when cilia on adjacent multiciliated cells beat slightly out of phase along the proximal-distal axis of the airways in alignment with anatomically directed mucociliary clearance. We hypothesized that metachrony optimizes mucociliary transport (MCT) and that disruptions of calcium signaling would abolish metachrony and decrease MCT. We imaged bronchi from human explants and ferret tracheae using micro-optical coherence tomography (µOCT) to evaluate airway surface liquid depth (ASL), periciliary liquid depth (PCL), cilia beat frequency (CBF), MCT, and metachrony in situ. We developed statistical models that included covariates of MCT. Ferret tracheae were treated with BAPTA-AM (chelator of intracellular Ca2+), lanthanum chloride (nonpermeable Ca2+ channel competitive antagonist), and repaglinide (inhibitor of calaxin) to test calcium dependence of metachrony. We demonstrated that metachrony contributes to mucociliary transport of human and ferret airways. MCT was augmented in regions of metachrony compared with nonmetachronous regions by 48.1%, P = 0.0009 or 47.5%, P < 0.0020 in humans and ferrets, respectively. PCL and metachrony were independent contributors to MCT rate in humans; ASL, CBF, and metachrony contribute to ferret MCT rates. Metachrony can be disrupted by interference with calcium signaling including intracellular, mechanosensitive channels, and calaxin. Our results support that the presence of metachrony augments MCT in a calcium-dependent mechanism.NEW & NOTEWORTHY We developed a novel imaging-based analysis to detect coordination of ciliary motion and optimal coordination, a process called metachrony. We found that metachrony is key to the optimization of ciliary-mediated mucus transport in both ferret and human tracheal tissue. This process appears to be regulated through calcium-dependent mechanisms. This study demonstrates the capacity to measure a key feature of ciliary coordination that may be important in genetic and acquired disorders of ciliary function.

A metaheuristic-optimization-based neural network for icing prediction on transmission lines

Ice accretion on overhead transmission line systems is a leading cause of power outages and can lead to substantial economic losses in northern regions. Therefore, accurately and rapidly predicting ice accretion on power lines is crucial for ensuring the safe operation of the power grid. This study introduces a machine learning method for predicting the ice-to-liquid ratio (ILR), an important parameter for assessing ice accretion efficiency. While estimating ILR is vital for operational forecasting, many existing ice accretion models do not include this capability. A feedforward neural network (FFNN) trained with stochastic gradient descent and various metaheuristic optimizers - specifically particle swarm optimization, grey wolf optimizer, whale optimizer, and slime mold optimizer - is employed to forecast hourly ILR. Environmental data required for training and testing the FFNN model were obtained from the Automated Surface Observing System (ASOS). A global sensitivity analysis using the Sobol index, evaluated via the coefficients of a polynomial chaos expansion, was conducted to identify the most influential input parameters. The results indicate that only four input parameters significantly contribute to the variance in the response: precipitation, temperature, dew point temperature, and wind speed. Furthermore, the FFNN model trained with metaheuristic optimizers outperformed the stochastic gradient descent approach. With the predicted ILR, ice accumulation can be easily calculated as the product of ILR and the amount of liquid precipitation depth.

Robust Intelligent Monitoring and Measurement System toward Downhole Dynamic Liquid Level.

Dynamic liquid level monitoring and measurement in oil wells is essential in ensuring the safe and efficient operation of oil extraction machinery and formulating rational extraction policies that enhance the productivity of oilfields. This paper presents an intelligent infrasound-based measurement method for oil wells' dynamic liquid levels; it is designed to address the challenges of conventional measurement methods, including high costs, low precision, low robustness and inadequate real-time performance. Firstly, a novel noise reduction algorithm is introduced to effectively mitigate both periodic and stochastic noise, thereby significantly improving the accuracy of dynamic liquid level detection. Additionally, leveraging the PyQT framework, a software platform for real-time dynamic liquid level monitoring is engineered, capable of generating liquid level profiles, computing the sound velocity and liquid depth and visualizing the monitoring data. To bolster the data storage and analytical capabilities, the system incorporates an around-the-clock unattended monitoring approach, utilizing Internet of Things (IoT) technology to facilitate the transmission of the collected dynamic liquid level data and computed results to the oilfield's central data repository via LoRa and 4G communication modules. Field trials on dynamic liquid level monitoring and measurement in oil wells demonstrate a measurement range of 600 m to 3000 m, with consistent and reliable results, fulfilling the requirements for oil well dynamic liquid level monitoring and measurement. This innovative system offers a new perspective and methodology for the computation and surveillance of dynamic liquid level depths.

Effects of operating parameters on single-stage ultrasonic separation of ethanol from its aqueous solutions

The effects of operating parameters on separation of ethanol from its aqueous solutions using ultrasonic atomization were investigated in a single-stage process. With an experimental setup similar to those used in previous work, we measured the degree of enrichment and the combined molar collection rate of ethanol and water for a single combination of the ultrasound power and frequency at 126 combinations of bulk liquid depth, composition, and temperature; carrier-gas inlet/outlet elevation and flow rate; and collection temperature. Enrichment depends strongly on bulk liquid composition, reaching a maximum at an ethanol mole fraction below 0.1, with the maximum enrichment depending on bulk liquid depth and inlet/outlet elevation. The collection rate depends strongly on inlet/outlet elevation and bulk liquid pool depth, and for high ethanol mole fractions is nearly independent of bulk liquid composition. Enrichment and collection rate increase with increasing bulk liquid temperature and decreasing collection temperature. The fact that increasing the carrier-gas flow rate increases the collection rate and decreases enrichment is interpreted in terms of size-selective transport of drops from the ultrasonically-generated fountain where they are atomized, to the cold trap where they are collected. The results are discussed in terms of operating parameters, transport phenomena (including evaporation and gravitational settling of atomized drops), the ultrasonically-induced fountain, and previously reported drop-size distributions. The duration of the experiments, conducted in batch, was such that the results should be relevant to both batch and continuous-flow operation. The work provides guidance and critical data for process scale-up.

Underwater half-space analysis to oblique 3D seismic waves based on exact free-field response

The seismic behavior of underwater half-space under arbitrary 3D incidence of P- or SV-waves is analyzed by the 2.5D finite/infinite element method. Firstly, the 3D responses of solid and liquid in free field are newly derived exactly, which cover both the sub- and super-critical conditions. Then, the equivalent seismic forces acting on the solid boundary of the 2.5D finite/infinite element method are merely computed from the free-field displacement for given earthquakes. Subsequently, the equation of motions for the underwater half-space under arbitrary 3D incident seismic waves are established in the 2.5D finite/infinite element system, with the key parameters specified. The proposed method was verified against the previous 2D solutions and inversely computed free-field solutions in frequency domain. Major conclusions drawn from the present analysis include: (1) The effects of liquid, concerning enlargement, reduction or disturbance, on the seabed responses become stronger for increasing liquid depth under sub-critical condition; (2) The seabed interior responses are less sensitive to the variation in liquid depth under super-critical condition; and (3) Under the super- and sub-critical conditions, respectively, more attention should be given to the interior response for P-waves and to the seabed surface response for SV-waves.

Effect of pressurant flow rate and ullage conditions on mass transfer and thermal stratification in a partially filled LN2 tank

Experimental and numerical computations have been carried out to investigate the evolution of pressure and temperature in the liquid nitrogen (LN2) tank pressurized with gaseous nitrogen (GN2). A parametric study has been carried out to study the effect of ullage volume and pressurant gas (GN2) flow rate (0.25–2 g/s) and temperature (250–350 K) on the pressure evolution and thermal stratification in the tank during active pressurization from 1 bar to 3 bar. Experiments are conducted in a small range of mass flow rates at a given pressurant gas temperature (302 K). The numerical simulations are validated with the experiments and a parametric study has been performed. It has been observed that pressurization time varies linearly with the liquid depth. Thermally stratified mass in LN2 increases with the decrease in pressurant mass flow rate for a given pressure rise. Numerical simulations revealed that mass condensed during the pressurization is a weak function of ullage depth and temperature but a strong function of the mass flow rate. The pressurant gas requirement follows the correlation of Ludwig and Dreyer (2014) for relatively higher mass flow rates. The pressurant gas temperature has a strong influence on the flow pattern in the ullage. The pressurant gas flows along the wall and reaches the interface without disturbing the bulk vapor. Heat transfer at the interface is dominated by the heat carried by the pressurant than by transfer from the bulk vapor.

Design, fabrication, and evaluation of a novel highly sensitive tuning fork pressure sensor for precise liquid level measurement

This article investigates the under-explored potential of utilizing a thin stainless-steel diaphragm coupled with a quartz tuning fork sensor for liquid depth measurements. The focus is on monitoring molten salt fluid levels in nuclear reactors and concentrated solar power systems. Addressing a literature gap, the research explores cantilever-type configurations of a double-ended quartz tuning fork resonator, with a no-load resonance frequency of 17.37 kHz, on thin stainless-steel diaphragms for fluid depth measurement at room temperature. As the fluid depth increases, hydro-static pressure acting on a 20 μm diaphragm causes deflection, bending a tuning fork. The resulting change in resonance frequency correlates with fluid depth. Experimental setups assess the tuning fork’s sensitivity to strain and bending, revealing strain sensitivity of 7.83 Hz/μ strain (450.78 ppm/μ strain) and bending sensitivity of 0.09 Hz/μm (5.18 ppm/μm). The pressure sensor assembly, tested in a water tank, exhibits a sensitivity of −0.28 Hz/mm (−16.12 ppm/mm) in a single cantilever-type configuration. Despite a limited linear range, it effectively measures water depth changes as small as 0.7 mm. Exploring a double cantilever-type configuration yields a sensitivity of 0.07 Hz/mm (4.03 ppm/mm) with a broader linear range. The article discusses the reasons for opposite sensitivity and highlights the advantages of each configuration. Beyond molten salt level monitoring, the technology’s applications may extend to fluid depth and pressure measurements in industrial and domestic settings.

Research on Dynamics Characteristic of The Filling Liquid Tank

The dynamics characteristic of the rocket tank with liquid propellant in it, which takes the large part of a carrier rocket, make a great influence to the whole rocket. The tank of some model was investigated systematically by the PATRAN finite element software. Firstly, it established a finite element modal of the tank and calculated the modal frequency and shape of the empty or filling tank by the virtual fluid mass and acoustic-structure coupling analysis. Then, it contrasted the veracity and applicability of the two methods and investigated how the liquid depth and density and the middle clapboard’s thickness influenced the immanent frequency of tank. Further, the filled tank’s characteristic of response was researched by the coupled acoustic-structural analysis. Finally, it investigated how the liquid depth and density influenced the filling tank’s characteristic of response. The main conclusions are shown below:1.The result of the filling tank’s modal is approaching to the test.2.Augmenting the density of liquid reduces the modal frequency of tank and increases the pulsant pressure of liquid.3.Raising the depth of liquid reduces the modal frequency of tank and increases the pulsant pressure of liquid.The paper’s achievement and conclusion will help to avoid the coupling between the launch vehicle structure and propulsion system and improve the dynamic stability. It also can provide references for design of the new tank according to the result.

Effect of Marangoni flow during the solidification of a Fe-0.82wt.%C steel alloy

A two-phase Mixture model is proposed to simulate the liquid-solid phase transition of a Fe-0.82wt%C steel alloy under the effect of Marangoni flow. This model simplifies computations by solving a single momentum and enthalpy equation for the mixture phase using a three-dimensional finite volume method. The simulation involves solidifying a rectangular ingot (100 × 10 × 100 mm3) from the cold bottom surface towards the hot-free surface at the top. To facilitate heat exchange with the surrounding environment, a high heat transfer coefficient of h = 600 W/m2/K was applied on the bottom surface to establish an upward solidification direction. However, a lower heat transfer coefficient of 20 W/m2/K was applied on the top free surface, which was considered flat. This study aims to examine the effect of Marangoni flow generated by surface tension on flow and segregation patterns. The results show that the Marangoni flow emerges at the free surface and penetrates into the liquid depth, leading to the formation of hexagonal patterns along the liquid thickness. Upon full solidification, macro-segregation also exhibits hexagonal structures, mirroring the stationary hexagonal shapes generated by Marangoni flow.