Limited Flow Rate Research Articles

Performance of packed and fluidized bed columns for the removal of unconventional oil using modified dolomite

The performance of modified dolomite for removing oil from laboratory synthetic oil-in-water (o/w) emulsions in packed bed (PB) and fluidized bed (FB) modes was investigated. The conditions (i.e., surfactant concentration, mixing stirring rate, and mixing time) at which the emulsion stability was found to be maximum were studied to increase the resistance of the dispersed oil droplets against coalescence. For the most stable emulsions, a series of experiments were performed to investigate the effect of parameters, such as influent oil concentration (400–650 ppm), flow rate (10–26 mL/min), and particle radii (0.08–0.15 cm) on the oil removal efficiency of the modified dolomite in a fixed bed treatment column. The breakthrough experiments were accomplished, and several aspects such as process operating conditions, mass transfer characteristics, and hydraulic characteristics of the columns were determined. Scaling up to 600 cm column with a diameter of 200 cm showed that with the same breakpoint criteria a large increase in the degree of utilization and a large decrease in average concentration in the outlet has been observed. To circumvent the occurrence of coalescence and flow rate limits for a fixed-bed column, a fluidized bed of hydrophobic dolomite was applied. A model was developed to predict the fixed and fluidized bed experimental results based on kinetic and equilibrium batch measurements of the modified dolomite and the stabilized o/w emulsion. The breakthrough curves in fluidized bed adsorbent were different than those obtained from fixed bed adsorbent due to axial mixing occurring in the solid and liquid phase.

Prediction of thermal potentials of multi-panel refrigerant heated radiator based on a mathematical model considering refrigerant flow distribution

The refrigerant-heated radiator (RHR) is an efficient and feasible heating terminal for space heating. In order to improve the efficiency of RHR, a multi-panel RHR was proposed in this paper. To investigate the thermal potentials of the multi-panel RHR, a heat transfer and pressure drop model of the multi-panel RHR was established. To predict the refrigerant flow distribution of the multi-panel RHR effectively, a hydraulic model was established. Combining the hydraulic model with the heat transfer and pressure drop model, a comprehensive mathematical model of the multi-panel RHR was set up. The feasibility and effectiveness of the mathematical model were validated with experimental data. The thermal potential of the multi-panel RHR was investigated with the mathematical model. The results indicated that the ratio of radiation to convection of the multi-panel RHR is 10.2%. Meanwhile, the refrigerant flow rate that makes the outlet refrigerants of all panels in the supercooled region is limited. Once the refrigerant flow rate reaches the limit value, the pressure drop of the RHR will increase rather than the heating capacity. Therefore, the predictions of the limited flow rate of RHR under different condensation temperatures are conducted, and relevant regressions can be extended to the RHR with more panels.

Quantifying Aerosolization of Facial Plastic Surgery Procedures in the COVID-19 Era: Safety and Particle Generation in Craniomaxillofacial Trauma and Rhinoplasty.

Background: COVID-19 poses a potentially significant infectious risk during procedures of the head and neck due to high viral loads in the nasal cavity and nasopharynx. Facial plastic surgery has significant exposure to these areas during craniomaxillofacial trauma procedures and rhinoplasty. Methods: Airborne particulate generation in the 1-10 μm range was quantified with an optical particle sizer in real time during cadaveric-simulated rhinoplasty and facial trauma conditions. Procedures tested included mandibular plate screw drilling, calvarial drilling, nasal bone osteotomy, nasal dorsal rasping, and piezoelectric saw use. Particulate generation was measured both adjacent to the surgical site and at surgeon mouth level (SML). Results: Mandibular plate screw drilling without irrigation generated significant particulate both adjacent to the surgical site and at SML (p < 0.01). Irrigation mitigated particulate generation at SML to nonsignificant levels. Calvarial drilling additionally produced substantial particulate above baseline adjacent to the surgical site (p < 0.01). Standard nasal osteotomies and dorsal rasping did not generate detectable airborne particulate, whereas piezoelectric saw use was associated with significant particulate generation both adjacent to the surgical site (p < 0.001) and at SML (p < 0.01). At SML, smaller particulate represented a significantly higher proportion of total particulate detected. Conclusions: The majority of craniomaxillofacial trauma procedures involve particle generation that may be limited in spread by the use of local irrigation. Most bony work involved in rhinoplasty can be safely performed without a high degree of particle formation. The use of piezoelectric instruments in rhinoplasty should be avoided when concerned for particulate generation.

Oxidizing-gas-based passivation of pyrophoric iron sulfides

Iron sulfides, as a class of common pyrophoric materials, are widely formed and deposited on the internal surface of transportation, storage, and refinery equipment in oil, petrochemical, and chemical industries. To reduce the self-heating risk from iron sulfides, this paper proposes a practicable method for inhibiting pyrophoric iron sulfides. Unlike existing inhibition methods, an oxidative gas mixture with a limited oxygen concentration and flow rate was employed in this study. The limited oxygen concentration and flow rate were determined using the following: (i) a combination of a trial-and-error method with a model developed through an experimental study and (ii) the support vector machine (SVM). In our experiments, the sulfurization and oxidation apparatus described in a previous study was improved, and then, the effects of mass deposition, concentration, and flow rate of oxygen on the self-heating property of pyrophoric iron sulfides were investigated. The results showed that the tendencies of the maximum oxidation temperature of pyrophoric iron sulfide versus the mass per unit area and oxygen concentration exhibited an approximate logistic fit, and for the oxygen flow rate, the tendency followed a log-normal fit. The developed SVM-based model is highly reliability in predicting the maximum oxidation temperature. Accordingly, a set of procedures for suppressing pyrophoric iron sulfide was given and explained by its implementation in a distillation column. Our proposed method was confirmed to be more effective, economic, and cleaner for the inhibition of pyrophoric iron sulfides.

Concentration Gradient Constructions Using Inertial Microfluidics for Studying Tumor Cell-Drug Interactions.

With the continuous development of cancer therapy, conventional animal models have exposed a series of shortcomings such as ethical issues, being time consuming and having an expensive cost. As an alternative method, microfluidic devices have shown advantages in drug screening, which can effectively shorten experimental time, reduce costs, improve efficiency, and achieve a large-scale, high-throughput and accurate analysis. However, most of these microfluidic technologies are established for narrow-range drug-concentration screening based on sensitive but limited flow rates. More simple, easy-to operate and wide-ranging concentration-gradient constructions for studying tumor cell–drug interactions in real-time have remained largely out of reach. Here, we proposed a simple and compact device that can quickly construct efficient and reliable drug-concentration gradients with a wide range of flow rates. The dynamic study of concentration-gradient formation based on successive spiral mixer regulations was investigated systematically and quantitatively. Accurate, stable, and controllable dual drug-concentration gradients were produced to evaluate simultaneously the efficacy of the anticancer drug against two tumor cell lines (human breast adenocarcinoma cells and human cervical carcinoma cells). Results showed that paclitaxel had dose-dependent effects on the two tumor cell lines under the same conditions, respectively. We expect this device to contribute to the development of microfluidic chips as a portable and economical product in terms of the potential of concentration gradient-related biochemical research.

Self-powered microfluidic pump using evaporation from diatom biosilica thin films

In recent years, researchers have successfully applied diatom biosilica to molecular detection platforms including Surface-Enhanced Raman Scattering (SERS) optofluidic sensors that are currently capable of detecting a variety of biological and chemical molecules at concentrations as low as 10−10 M. This study investigates the feasibility of an SERS device that couples the sensing and pumping capabilities of diatom biosilica thin films by determining flow rate limitations and stability. In this paper, we quantify the ability of porous diatom biosilica thin films to continuously pump deionized (DI) water from a reservoir via wicking flow by utilizing the strong capillary forces of the porous film coupled with evaporation. Our microfluidic device is comprised of a narrow horizontal reservoir fixed to a horizontal capillary whose end contacts a diatom biosilica film. Flow rates were controlled by altering the size and/or temperature of the biosilica porous film, determined by tracking the liquid meniscus displacement in the reservoir, and correlated with a modified laminar boundary-layer model. System stability was observed by tracking flow rates over the course of a given experiment, image analysis of the meniscus contacting the film, and a flow duration study. We found that for untreated DI water bubbles begin to form in the capillary tube at temperatures above 40 °C, but degassed water remains stable at temperatures of 90 °C and below. The pumping capabilities of the films ranged from 0.11 to 10.46 µL/min, matched theoretical predictions, demonstrated stable flow trends, and maintained flow for over 48 h.

Pitfalls of anesthetic management with the Impella\xae 5.0 device: a case series

BackgroundImpella® is an antegrade left ventricular assist device with a pump catheter in the left ventricle. We report three cases in which we experienced some pitfalls with circulatory management during Impella placement due to new-onset aortic insufficiency (AI) associated with device placement or the limited maximum flow rate.Case presentationThree patients developed new-onset AI due to Impella placement. In a patient, the total assisted flow rate was relatively low because of his large body size. In the other patients, in whom the Impella device was used in combination with percutaneous cardiopulmonary support or venoarterial extracorporeal membrane oxygenation (ECMELLA), total flow was maintained at a sufficient level.ConclusionsNew-onset of AI after Impella placement and its limited flow rate are considered to be pitfalls in circulatory management. Management with ECMELLA is considered to be effective during the acute phase when patients have decreased cardiac function.

Stable multi-jet behavior of ethanol under an electric field

Electrospray is a mass transfer technology in which charged liquid is broken into fine droplets/particles with ideal monodispersity, easy controllability, and high-deposition . In recent decades, with the rapid development of various micro precision instrument technologies, the research of electrospray has been widely applied to micro/nano-scaled thin film and particle preparation, air purification, micro-combustion, space micro-propulsion, mass spectrometry, and biotechnology. Previous researches mainly focused on the stable cone-jet mode that has the advantages for producing several micron-sized particles or droplets with good stability and monodispersity. However, electrospray in this cone-jet mode has a major disadvantage that restricts the practical application of electrospray. The droplet size in the cone-jet mode increases with an increase of the flow rate, and this means the production of tiny droplets limits the supply flow rate, and this limited flow rate cannot meet the requirements for atomization flow in practical application. Multi-jet is an important operation mode in electrospray, and sub-droplets of comparable size to the sub-droplets produced by cone-jet can be obtained on the basis of multiplication of the single capillary flow. However, multi-jet atomization is very unstable, and it is difficult to attain a stable jet atomization state; therefore, in-depth research on the evolution of its morphology and atomization characteristics is necessary to expand the practical application of electrostatic atomization technology. Based on high-speed photography technology with a high spatial-temporal resolution, the influence of capillary geometry, electrode spacing, liquid supply flow rate, and applied voltage on the multi-jet formation and evolution in electrospray was studied in detail. The electric bond number and the dimensionless flow rate were introduced to describe their action laws on the evolution behavior of the stable jet number, stable atomization range, and jet deviation angle in the stable multi-jet mode. The research results show that the range of the number of stable jets N of multi-jet is from 2 to 10. When 2≤ N N ≤10, the jets are ejected from the outer edge of the capillary orifice to form an edge jet mode, and it is particularly important to note that the occurrence frequency of the stable 5–8 strands is higher than other strands. In the edge mode, as the number of stable jets increases, the range of the electric bond number of the stable multi-jets and the critical minimum electric bond number gradually increases, and a voltage switching phenomenon of stabilizing multi-jet is also presented. As the dimensionless flow rate increases, the maximum value of the electric bond number under each number of stable jets shows a linear growth trend. The maximum value of the electric bond number increases with the increase of the stable jet number under the same flow rate, and a significant increase in the minimum value of the electric bond number is observed. Additionally, as the number of stable jets in the edge mode increases, the overall deviation angle of the jet increases, but the range of variation of the deviation angle of each stable jet number is controlled within 5°±0.3°. Moreover, as the electric bond number increases, the jet deviation angle gets closer to 45°, which indicates that the electric field force dominates the jet deviation as the electric field intensity increases.

Running Limit and Refusal in Rock Fractures Grouting

Absolute refusal is in practice impossible to achieve and is substituted by the minimal flow criterion. Grouting is stopped when the flow rate is less than a predefined quantity known as the flow rate limit. The majority of the grouting models and procedures do not mention how to calculate the flow rate limit if they do not specify empirical values. A parametric relation for the flow rate limit is obtained in this note. It binds the flow rate to the target, effective pressure, fracture opening, mix rheology and borehole. It is a flexible relation from which it is deduced that there is no need to use either the highest injection pressure or a constant pressure to attain the target. The monitored pressure can be used transforming the flow rate limit into a Running Limit. A practical case will illustrate the use of the running limit for a back-analysis of the log data of a grouting stage at La Yesca hydroelectric project. Subsequently, the minimal flow criterion will be inserted in three of the main grouting models RTGC, GIN and ALT, which will require special handling to preserve the specifications of each model.

Effect of Pipe Diameter and Inlet Parameters on Liquid CO2 Flow in Transportation by Pipeline with Large Height Difference

Fire prevention and extinguishing and CO2 sequestration in coal mine gob require continuous transportation of liquid CO2 in pipelines with large height difference (from ground to underground). However, the temperature and pressure variation of liquid CO2 in pipelines with large height difference is still unclear, which hinders the design of a liquid CO2 pipeline transportation system. The influence of pipe diameter and inlet parameters (temperature and pressure) on the variation of temperature and pressure of liquid CO2 along the 1000 m vertical pipeline was studied in this paper. The study found that for each pipeline diameter considered there existed a range of flowrates where safe flow conditions could be ensured, at which no phase transition occurs throughout the length of the pipeline. When the transporting flow is larger than the maximum limit flow, phase transition occurs dramatically, which will lead to a sudden drop in temperature and pressure. When the transporting flow rate is lower than the minimum limit flow rate, phase transition of CO2 occurs slowly along the pipeline. According to the requirement of underground fire prevention and extinguishing for transporting flow rate and the economic cost of the pipeline system, the optimum diameter is 32 mm, and the corresponding safe transporting flow range is 507–13,826 kg/h. In addition, when the inlet pressure is constant, if the inlet temperature is too high, phase transition of CO2 occurs dramatically at the entrance. For a 1000 m vertical pipe with diameter of 32 mm, when the inlet pressure is 14 bar, 16 bar, 18 bar, 20 bar, 22 bar, 24 bar, the corresponding maximum allowable inlet temperatures are −30 °C, −26 °C, −23 °C, −19 °C, −16 °C and −13 °C, respectively. This research has significant guidance for safety transportation scheme of liquid CO2 from coal mine surface to underground.

Packed bed compression visualisation and flow simulation using an erosion-dilation approach

X-ray computed tomography has been demonstrated to be capable of imaging 1 mL (5 mm diameter, 50 mm height) chromatography packed beds under compression, visualising the 3D structure and measuring changes to geometry of the packing. 1 mL pre-packed columns did not exhibit any structural changes at vendor specified flow rate limits, however cellulose beds did compress at higher flow rates that were imaged before, during and after flow. This was used to visualise and quantitate changes to porosity, tortuosity and permeability based on simulation of flow through the packed bed structure using the imaging data. When using a high flow rate it was found that a decrease in porosity could be measured during compression before reverting after flow had ceased, with corresponding changes to tortuosity and permeability also occurring.X-ray CT imaging of packed beds and individual beads exposed to foulant-rich process streams resulted in considerable image quality loss, associated with residual biological material. In order to address this, digital processing using an erosion-dilation method was applied at bead and bed scales to computationally alter the porosity by adding or removing material from the existing surface to calculate the impact upon tortuosity factor. The eroded and dilated bead volumes of agarose, cellulose and ceramic materials were used to simulate diffusivity whilst mimicking internal bead pore constriction and blocking mechanisms.

Анализ основных тенденций инновационного преобразования математической модели потокораспределения в газоснабжающих системах и приобретаемых ими новых свойств

The purpose of the paper is to consider the proposals for the possible account of new properties of gas supply system in a mathematical model of the generalized problem of flow distribution as compared to the traditional formulation; to introduce an arc coefficient considering gas flow value alteration when passing through the arc, increment vector of arc flow rate and lower limits on gas flows in the arcs; to analyze new management conditions (optimization criteria of load flows and establishment of fictitious gas consumption prices allowing to take into account a high priority supply of a certain group of consumers). Network analysis methods are widely used in solving the problems of long-term planning and development of gas supply systems for mathematical modeling of optimal gas flows. The account of new trends of innovative transformation in mathematical models is caused by the modern development of gas supply systems, their renovation and modernization. To solve the problems of gas load flow in gas supply systems the network analysis methods based on the graph theory are used when dealing with the problems of gas supply system operation in various conditions. Based on the traditional problem of flow modeling a generalized solution of load flow is formulated taking into account the new properties of gas supply system. A mathematical formulation is given, its implementation is successively executed in the computational program. The gas flow calculation for the aggregate Unified gas supply system in 2030 is given as an example of the proposed approaches. This calculation takes into account the capacity increments of gas transmission system arcs and the coefficients showing a decrease in the volumes of gas supply for own needs and leakages. To solve the problems of load flows in the optimization of gas supply system development the following innovative improvements have been proposed: arc coefficients taking into account gas flow value alteration when passing through the arc are introduced; increment vectors of arc capacities and gas flow lower limits in the arcs are given, new economic conditions (flow load optimization criteria and fictitious prices on gas consumption) allowing to consider a high priority supply of a certain group of consumers are taken into account.

TRACE code demonstration of thermal stratification in BWR suppression pool

An analytical model was developed to describe thermal stratification in a primary containment vessel (PCV) and transient thermal-hydraulics coupled with a reactor pressure vessel (RPV) using TRACE code version 5.0 patch level 4. Geometries of a dry well (D/W) and a suppression chamber (S/C) were represented by a nodalization of TRACE code to simulate multi-dimensional flow in the PCV. An additive loss coefficient (so called ‘K-factor’) was focused as a sensitivity parameter to limit flow rate in a pool. For the first step, a validation analysis was conducted against a steam discharge experiment of S/C. The TRACE result was in good agreement with the measurement and showed a thermally-stratified temperature distribution in the S/C pool. For the second step, an analysis to simulate the accident at Fukushima Daiichi Unit 3 power plant (1F3) was conducted. It was proved to be able to explain the pressure increase in the PCV at the beginning of accident by demonstrating thermal stratification in the S/C pool. Sensitivity study revealed an optimal K-factor value for a macroscopic viscous drag in a liquid phase fluid to demonstrate thermal stratification in a pool.

Three-dimensional simulation of a new cooling strategy for proton exchange membrane fuel cell stack using a non-isothermal multiphase model

In this study, a new cooling strategy for a proton exchange membrane (PEM) fuel cell stack is investigated using a three-dimensional (3D) multiphase non-isothermal model. The new cooling strategy follows that of the Honda’s Clarity design and further extends to a cooling unit every five cells in stacks. The stack consists of 5 fuel cells sharing the inlet and outlet manifolds for reactant gas flows. Each cell has 7-path serpentine flow fields with a counter-flow configuration arranged for hydrogen and air streams. The coolant flow fields are set at the two sides of the stack and are simplified as the convective heat transfer thermal boundary conditions. This study also compares two thermal boundary conditions, namely limited and infinite coolant flow rates, and their impacts on the distributions of oxygen, liquid water, current density and membrane hydration. The difference of local temperature between these two cooling conditions is as much as 6.9 K in the 5-cell stack, while it is only 1.7 K in a single cell. In addition, the increased vapor concentration at high temperature (and hence water saturation pressure) dilutes the oxygen content in the air flow, reducing local oxygen concentration. The higher temperature in the stack also causes low membrane hydration, and consequently poor cell performance and non-uniform current density distribution, as disclosed by the simulation. The work indicates the new cooling strategy can be optimized by increasing the heat transfer coefficient between the stack and coolant to mitigate local overheating and cell performance reduction.

Flow Induced Vibration (FIV) Research of Oil and Gas Process Piping System

Piping systems in crude oil production facilities tend to handle high pressure and high velocity flowing fluid at certain flow rate limit resulted in generation of turbulence flow. This turbulence can generate high levels of broad band kinetic energy which can propagate through the system. Even though the energy is distributed across a wide frequency range, most of the excitation is concentrated at low frequency (typically below 100 Hz); the lower the frequency, the higher the level of excitation from turbulence. This leads to excitation of the low frequency vibration modes of the pipe work, in many cases causing visible motion of the pipe and, in some cases, the pipe supports, and this phenomenon is called Flow induced vibration (FIV) and if excessive can result in fatigue failure. This objective of the paper is to identify potential sources of FIV on piping by predicting the Likelihood of failure (LOF) and advising on the necessity for system modifications to minimize or eliminate any FIV induced piping or line failure from Flow Induced Turbulence. These are done by conducting a FIV assessment for piping systems in oil production facilities which are potentially affected by vibration due to both process conditions and mechanically induced pipework vibration. Another scope of this paper is to apply the recommendation action required in order to reduce the likelihood of failure by changing pipe diameter and/or wall thickness by looking at the fluid structure interaction (FSI). By changing the outer diameter and the wall thickness of the pipe, the formation of the excitation in flow regime and the presence of the critical flow disturbance will decrease. These changes are able to reduce the formation of FIV thus increasing the lifespan of the piping system

The displacement ventilation patterns in two parallel-connected chambers with a mechanical extraction device

This research studies the mechanical extraction ventilation in two parallel-connected chambers. A buoyancy source is located in one chamber, denoted as the forced room, and there is an extraction device in the other chamber, denoted as the extraction room. Two chambers have their own connecting openings to the ambient in the parallel-connected model. This paper focuses on the displacement ventilation pattern with a mechanical extraction device in the steady state. The flow driving forces include the buoyant and inertia forces in the mechanically ventilated space. The buoyant force results from a buoyancy source, and the inertia force, or suction force, is due to the mechanical extraction device. In this research, two different flow regimes are found in two parallel-connected chambers depending on the control extraction flow rate magnitude, and the upstream forced chamber is found to have a certain maximum flow rate limit in this configuration. When the control extraction flow rate is less than or equal to the limit value, both of the forced and extraction chambers have the same flow rate as the control extraction flow rate and the supply fluid from the exterior only goes through the forced chamber into the interior space. However, when the extraction flow rate is larger than the limit value, the enhancement flow rate of the forced chamber is more than the maximum flow rate limit, and the extraction chamber starts to bring some complementary flow rate from the exterior.

Estilos eruptivos asociados al volcanismo monogenético máfico de la región de Pasto Ventura, Puna Austral, Argentina

One of the most outstanding features of the Southern Puna is the occurrence of a widespread monogenetic mafic volcanism during Neogene-Quaternary. Despite a number of published papers focusing on the petrogenesis of this back-arc volcanism, works aimed on its physical volcanology are scarce. This paper presents the characterization of the monogenetic mafic volcanism in the Pasto Ventura region, located in the southeast edge of the Southern Puna. The results show that in the Pasto Ventura region there is a low density of small-volume eruptive centers aligned with regional tectonic structures and a significant variability in eruptive styles (effusive, strombolian, hawaiian, violent strombolian and phreatomagmatic) and typology of volcanic structures (domes, scoria cones, maars and tuff rings). The first of these features is explained by a limited magma flow rate from the deep source and the use of favorable tectonic structures (oriented obliquely to the regional maximum compression direction) for the ascent of small volumes of magma through the upper crust. The variability of eruptive styles responds to the complex interaction of different endogenous and exogenous factors. The occurrence of effusive or explosive eruptions depends on the differences in magma ascent rates including periods of stagnation in the upper crust, which in turn control the efficiency of degassing and ultimately the occurrence of fragmentation. On the other hand, the more humid local climatic conditions (~150 mm/year), which are related to the geographical position of the Pasto Ventura region in the eastern edge of the Puna, favor the occurrence of phreatomagmatic activity. Phreatomagmatic activity also varies according to the topography, substrate typology and depth at which water-magma interaction occurs.

Characterization of the Mixing Flow Structure of Molten Steel in a Single Snorkel Vacuum Refining Furnace

With the demand of high-quality steel and miniaturization of the special steel production, single snorkel vacuum refining process has been widely concerned in China recently, because of its simple structure and good performance of degassing and decarburization. In this study, a water model experimental system and a three-dimensional mathematical model based on two-fluid multiphase flow model have been built to analyze the refining efficiency limitation of the single snorkel vacuum refining furnace from the flow pattern and gas distribution. The results showed that there is a limited gas flow rate, and beyond this flow rate the gas column deviates to the wall and the redundant bubbles escape from the free surface, which will not further improve the refining efficiency and will lead to the erosion of the snorkel. In this case, the limited flow rate is 900 NL/h. Furthermore, the fluctuation of the free surface and the different structural parameters have significant effects on the flow field in single-snorkel vacuum refining furnace (SSF).

Flow rate limitation in curved open capillary groove channels

This paper is concerned with the forced flow through curved open capillary channels under microgravity conditions. A maximum flow rate in the open capillary channel achieves when the flow rate exceeds a certain value and the free surface collapses leading to the gas ingestion. The gas ingestion is not desired for most of the applications. In order to prevent it and enable an optimal performance, it is vital to understand the influences of the channel geometry parameters and liquid properties on the maximum flow rate. In this paper, the one-dimensional theoretical model successfully applied to the straight open capillary channel is extended to the curved open capillary channel. The result shows that under the same boundary conditions, the maximum flow rate in the curved open channel is smaller than that in the straight open channel. The maximum flow rate decreases with the curvature of open channel increasing. By analysis, the pressure loss and the centrifugal force effect due to the curve motion in a curved path are considered to be the cause of the maximum flow rate difference between the curved channel and the straight channel. It is found that the centrifugal force effects weaken the pressure difference balance ability of the free surface and the pressure loss in the curved open channel is greater than that in the straight open channel. By comparison, the one-dimensional theoretical results agree well with CFD simulations and the average relative error is only 1.51%. Furthermore, the parametric study of flow in the curved open capillary channel depicts that the maximum flow rate increases with the channel curvature or aspect ratio increasing, and decreases with the open channel length, contact angle or Ohnesorge number increasing. This conclusion can be utilized to design the open channel in space liquid management system.

Surface Smoothness Evaluation of Etched and Unaltered Sand Specimens with Mechanical Behavior Assessment

Abstract Particle smoothness refers to the surface texture of a sand particle on a small scale. This parameter may be used in conjunction with roundness (angularity) and sphericity in describing particle shape for engineering purposes. Smoothness is challenging to measure and quantify. This note describes preliminary evaluation approaches used to compare two identically graded sand specimens; one with an unaltered, smooth surface texture, and the other chemically etched to create a rougher surface texture. Visual observation indicated that the unaltered specimens were essentially the same as the etched specimens in terms of macroscale particle shape features (i.e., roundness and sphericity). On the other hand, the particles were significantly different in terms of the surface texture and roughness, as shown by visual techniques using scanning electron microscope and optical microscopy images. A tentative, easy-to-implement, visual particle smoothness scale is offered, designed to complement the roundness and sphericity estimates and measures commonly used to describe particle shape. Next, several simple laboratory index tests are completed on the unaltered and the etched specimens to observe differences in mechanical behavior. Limit density, flow rate, and angle of repose tests are undertaken. The results of the testing indicate measurable differences in the mechanical behavior of the unaltered versus the etched specimens. This further supports the importance of particle surface texture on the mechanical behavior of poorly graded sands. Additional research is underway to more completely quantify the contribution of particle smoothness of sands with respect to the other macroscale particle shape features.