Air Suction Research Articles

GAS DYNAMIC ANALYSIS OF THE SINTER CHARGE IGNITION PROCESS

To increase the productivity of sintering machines, sinter quality and economy of the gaseous fuel, it is necessary to ensure the optimal mode of external heating of sintering charge layer. The effect of sintering machine vacuum chamber throttling under the ignition hearth on the gas-dynamic mode of charge ignition and sintering, including the quality of sinter, sintering machine productivity, gas consumption for the charge ignition and the possibility to control and manage the charge humidity were considered. It is shown, that throttling of the first vacuum chambers allows reduction in the fuel consumption, charge shrinkage, amount of air suction into the ignition hearth and gas-discharge duct of the sintering machine and improvement of the sinter quality. The effects of air rarefaction on charge layer surface temperature and sinter quality are provided. The structural variants of vacuum chamber throttling implemented in practice are presented; two of them operate at sintering machines at Bhilai Iron and Steel Works, India. It is shown that throttling of the first vacuum chambers located under ignition hearth is effective for charge ignition and sintering processes in all cases and should be obligatory during the sinter production.

Resection of posterior fossa tumors in the semi-sitting position in children younger than 4 years of age

PurposeThe semi-sitting position for resection of posterior fossa tumors is a matter of ongoing debate. Here we report about our experience with this approach in children younger than 4 years of age.MethodsWe retrospectively analyzed data of children younger than 4 years of age operated on in our institution in the semi-sitting position over a 15-year period. Patients were intraoperatively monitored for venous air embolism (VAE) by transthoracic Doppler (TTD) or transesophageal echocardiography (TEE). The severity of VAE was classified according to the Tübingen grading scale. Intraoperative incidents of VAE were recorded and the patients’ course was followed postoperatively with a special focus on possible complications.ResultsTwenty-four children (18 boys, 6 girls) were operated on in the semi-sitting position (26 operations). Mean age was 2.2 years (± 1.0), range between 0.4 and 3.9 years. External ventricular drains were inserted in 18 children with hydrocephalus preoperatively. VAE was detected in 6 instances during surgery (6/26 (23.1%)). In 3 patients with grade 1 VAE, no additional treatment was necessary. In one patient with grade 2 VAE, intracardiac air suction via the central venous catheter was performed, and in two patients with grade 4 VAE, additional cathecholamine-infusion was administered. No major intraoperative complications occurred. Postoperative CT images showed pneumocephalus in all children. In two children, small asymptomatic impression skull fractures at the site of the Mayfield pin occurred. Revision surgery was necessary in one child with a suboccipital CSF fistula.ConclusionThe semi-sitting position for resection of tumors in the posterior fossa in children younger than 4 years of age can be safely performed in experienced centers taking special caution to detect and treat potential complications in an interdisciplinary setting.

Development of a Novel Biomimetic Mechanical Hand Based on Physical Characteristics of Apples

For the purpose of minimizing the damage to apples during the operation of an apple-picking robot, improving the stability of an apple-harvesting mechanical hand and reducing the use and operation cost of the robot, a novel biomimetic apple mechanical hand based on negative pressure air suction is purposely designed based on the physical characteristics of apples by imitating octopus predation. The mechanical hand has four suction cups evenly distributed in the hand, which produce concave deformation under negative vacuum pressure to fit the apple surface and adsorb the apple; the fruit stalk is separated by wrist rotation and dragging in a compound way to complete the picking operation. This paper firstly determines the key parameters of the mechanical hand based on the characteristics of silicone material and the three growth postures of apples, tries to make a physical prototype of the mechanical hand and conducts relevant performance tests on the picking platform built in the laboratory to explore the best combination of parameters and further optimize the manipulator. The results show that the success rate of the biomimetic nondestructive apple picker with the best combination of parameters is 100%, 76% and 68% for three different apple-growth postures and the operation is smooth, reliable, safe and non-invasive.

UJI PEFORMA RANCANG BANGUN PORTABLE VACUUM GRAIN CONVEYOR TIPE CENTRIFUGAL FAN

Portable vacuum grain conveyor (PVGC) work as transporting grain materials such as grain, wheat, sorghum, corn and its kind using air media. The advantages of this machine are that it can move material quickly, the material does not fall in the transportation process, it can move from the bottom to the top or vice versa, it does not require a feed hopper, and the machine can move places. How the PVGC machine works by utilizing the suction and thrust of a vacuum blower. The seed material is sucked in by the input hose and then into the cyclone to separate the air and seed material. Air from the cyclone enters the vacuum blower through the input hole and is blown into the output line to push the material falling from the cyclone through the rotary airlock. Seed material out through the output hose is directed to the desired place. Performance testing of the PVGC engine includes noise, the air suction speed of the input hose and the thrust speed of the output hose, the engine capacity, and thermal testing. The highest noise test results in the electric vacuum blower motor was 95.5 dBA ±1, the air suction speed at the input hose was 38 m/s ±3, the air thrust speed at the output hose was 44 m/s ±2, the capacity of the PVGC machine could transport IR64 of grain type with weighing 88 kg/minute. The hottest component was in the vacuum blower with a temperature of 52.50C.

High-Resolution Surface Replication of Living Organisms using Air-Through-Precursor Suction-Augmented Replica Molding.

Replica molding is widely used to reproduce the surface microstructures that provide living organisms with distinct and useful functions. However, the existing methods are limited by the low resolution resulting from the air trapped in the structures during precursor solution loading. This study investigated replica molding with an air-through-precursor suction (APS) process, which used a degassed polydimethylsiloxane substrate to remove the trapped air through the precursor solution. The liquid loading times arecharacterized using a model template, and air suction that isup to 36 times faster can be achieved using the APS process relative to a conventional method. Using APS replica molding, biocompatible replicates from human fingerprints and gecko skin arefabricated using only a 3min precursor solution loading step. Owing to the enhanced and reproducible resolution from APS replica molding, for the first time, the structural changes in the foot of a living gecko at the microscale can be observed when standing on a horizontal or vertical surface.

Design of an Air Suction Wheel-Hole Single Seed Drill for a Wheat Plot Dibbler

Focusing on the problems of the poor filling ability and stability of the mechanical wheat seeder and the complicated structure of the pneumatic seeder, a special air suction wheel-hole single seed drill for remote controlled self-propelled single seed dibbler in wheat plots was designed in this paper. According to the agronomic requirements of precision seeding in wheat plots, the seeding wheel radius was set at 180 mm 16 suction holes. Using the discrete element simulation software EDEM to analyze the seed disturbance effect of different parameter designs, the thickness of seed suction ring was 16 mm, the height of seed suction mouth was 4.5 mm, and the diameter of seed suction cam was 12 mm. Through hydrodynamic simulation, the phase angle of the negative pressure chamber was 280 degrees, positive pressure chamber was 22 degrees, phase angle of the unpressurized interval zone was 20 degrees, thickness of the negative pressure chamber was 24.5 mm, diameter of transition pipe was 17.5 mm and length of the transition pipe was 14.5 mm. Based on the above design parameters, the samples were then processed and benchtop experiments carried out. The results showed that under the best operating parameters, the re-suction index was 0.82%, the leakage index was 6.67%, and the qualified index was 92.41%, which met the design requirements. This study could provide a reference for the design of single-seed dibbling technology in wheat plots.

Air circulation study inside and outside of urban buses induced by the opening of windows.

In this work, the external and internal airflow analysis in an urban bus is carried out through computational fluid dynamics. The research addresses the study of the internal flow to estimate the air change rate caused by the opening of windows. Two cases are considered: fully opening and partially opening the windows, and three bus speeds of 20, 40, and 60 km/h are assessed. The quantification of the air flow rate through the windows clearly displays that air enters through the rear windows and exits the bus through the front windows. This effect is explained by the pressure distribution in the outer of the bus, which causes the suction of the indoor air. At low bus speeds, the incoming air flow rate increases linearly with the speed, but the improvement is lower for high speeds. The theoretical air change time at 20 km/h is around 25.7 s, which is 9 times lower than expected by using HVAC systems. On the other hand, the estimation of the real air renewal time by solving a concentration shows that 40 s are needed to exchange 85% of the internal air of the bus. The research also assesses the effect of different levels of occupation inside the bus. Results are conclusive to recommend the circulation with full or partial window opening configurations in order to reduce the risk of airborne disease transmission.

Design of an Acoustic Synthetic Jet Actuator for Flow Control

Synthetic jet technology is widely adopted in active flow control. An actuator with an oscillating diaphragm is a commonly used excitation device for synthetic jet generation. However, it has a disadvantage wherein the volume at the cross-section of the cavity varies unevenly when the diaphragm vibrates, which makes it difficult to use multiple jets corresponding to one diaphragm. In this paper, an acoustic synthetic jet actuator that can generate multiple jets with one diaphragm was designed. The diaphragm vibrated in a cylindrical cavity, transferring air to another constant-volume square cavity through pipes. The square cavity was covered with a multiple-orifice plate for the expulsion and suction of the ambient air. Through this means, the implementation of multiple jets corresponding to one diaphragm was achieved. The multiple jets are called distributed synthetic jets in this paper. Governing parameters that determined the performance of the distributed synthetic jets were given by theoretical derivation. It was found that, under specific geometry conditions, the governing parameters were mainly the frequency and voltage of the input signal to the actuator. Then, the velocity characteristics of the distributed synthetic jets were measured by using a constant-temperature anemometer and the parameter space was determined. The results showed that it was practicable to apply the acoustic actuator to turbulent boundary layer flow control.

Numerical simulation of heat transfer and hydraulic losses of air-cooled exhaust-shaft apparatuses

The article presents the numerical simulation results on heat transfer and hydraulic losses of air-cooled exhaust-shaft apparatuses. Studies were made on air-cooled apparatuses in which four-row bundles of staggered finned tubes were placed. Numerical simulation used a gas dynamic solver Ansys Fluent. Menter’s shear stress transport κ-ω model was invited to close the Reynolds equations. The obtained numerical results allowed us to visualize air flow in the bundle and the exhaust shaft, as well as to establish an inhomogeneous distribution of velocities and temperatures. We found that the temperature distribution in the flow passing through the exhaust shaft depends on the height of the exhaust shaft. We also established that at small shaft heights in the wake behind a bundle because of the wake oscillatory motion, the dynamic and temperature inhomogeneous distributions take place, resulting in the cold air suction through the shaft from the environment. With an increase in the shaft height, the inhomogeneous temperature distribution moves upstream the air flow in the shaft and the inhomogeneous temperature distribution attenuates. We can say that maximum heat transfer at the same hydraulic losses is achieved when mounting a shaft with a height of H > 1.16 m. The results obtained can be used for the modernization of existing air-cooled apparatus, as well as for the design of new devices with an exhaust shaft.

Observational Analysis of Stationary C.I. Engine Output and Emission Evaluation for Variance of Induction Pressure Aspects

In the current environment, improved engine performance, reduced fuel consumption and reduced emissions are important goals for automotive manufacturers. To understand the factors involved in the compartment assemblies in Compression Ignition (C I) engines it is crucial to concentrate on such goals. Pressure rating, fuel atomization, fuel pressure, fuel quality, air pressure rating, air temperature, pressure and other design components such as piston, Air induction system, and assembly chamber and more to work. It is evident from the literature review and research work carried out to date that the airing system is best method of promoting C I operation of the engine. The design of the Air suction system could be achieved in this way that it takes into account the objectives of entire system. Effective air suction system improvement needs least energy utilization and most extreme use of air intake pressure for decrease in poisonous productions at outlet of C I engines. Furthermore, powerful use of fuel vitality. In present work, air suction arrangement, exclusively less air inlet pressure during suction stroke of four stroke cycle engine concern is topic of explicit enthusiasm for plan. Advancement of air induction system with air induction pressure regulator, flow distribution, action is studied and useful information is developed through proper intake manifold arrangement for better fuel efficiency.

Numerical simulation of propulsive aerodynamic profiles

The problem of creating high-lift propulsive aerodynamic is considered. A method was developed for constructing an aerodynamic profile by solving the inverse problem of aerodynamics. The dependence of the lifting force of this profile on the volume of air sucked from its upper surface and from the angle of attack is studied. The profile under study was developed on the basis of the well-known Griffin/Goldschmid profile with air suction at the upper critical point. Three aerodynamic profiles have been developed. The first profile has a flat lower surface to obtain the ground effect. The second profile is similar to the first but has a slit nozzle near the trailing edge. The third profile is similar to the second but has a non-flat bottom surface and increased thickness. The solution of the inverse problem of aerodynamics was used to construct aerodynamic profiles within the model of an ideal gas. The pressure distribution on the upper part of the profile, its construction height and the range of angles of attack are from 0° to 16°, as well as the degree of rarefaction up to 0.5 atm in the gap through which the air was taken were set. For the second and third profiles, the ratio of the amount of air ejected through the nozzle to the amount of air taken from the upper surface of the profile was set. This ratio ranged from 50 % to 200 %. Numerical calculations were performed for each variant using the Spalart-Allmaras turbulence models and the Transition Shear Stress Transport (SST) and Langtry model. The parameters of the turbulence models were adjusted according to known reference data. The Reynolds number was in the range of 1.5·105–1.5·106. The profiles have a high lift coefficient Cy = 3–3.4 which is achieved when creating a vacuum in the air intake of 0.5 atm. Cy depends on the angle of attack almost linearly up to the maximum values. The greater the air flow through the slot nozzle, the greater is the Cy at a vacuum in the air intake of 0.5 atm. Significance for practical application. The developed profiles have a large thickness and create traction. These profiles are convenient to use in aircraft with large internal volumes, for example, those running on hydrogen fuel.

A Young Man With Epigastric Abdominal Pain

A Young Man With Epigastric Abdominal Pain

Cooling Characteristic of an Infrared Suppression Device With Single Perforated Funnel: A Computational Fluid Dynamics Approach

Abstract An infrared suppression (IRS) device is integral to any gas turbine used in naval and cargo ships. Estimating an IRS device’s cooling characteristics is essential to start the maintenance operation. Thus, this article presents a computational investigation of the cooling characteristics of an infrared suppression device with a single cylindrical funnel with or without circular perforations. All simulations have been carried out in a steady and laminar environment. The numerical procedure adopted in this work has been validated with the existing correlations and achieved satisfactory agreement. The effect of the Rayleigh number and the length-to-diameter ratio of the funnel have been varied within the practical range to observe their effects on the averaged Nusselt number, heat transfer rate, mass suction rate, velocity fields, and thermal plumes. Moreover, the cooling performance has been compared for funnels without and with circular perforations. It is observed that the average Nu and the heat transfer rate increase with an increase in the Ra. Conversely, the average Nu first increases and then reduces with an increase in L/D. On the contrary, the heat transfer rate decreases monotonically with an increase in the L/D. The suction of fresh air into the funnel increases with Ra, whereas it reduces with an increase in L/D. The perforated funnels have better heat dissipation capacity than the unperforated ones.

The influence of ventilation parameters on dust pollution in a tunnel's environment using the CFD method

A shield tunneling boring machine produces a large amount of dust during the excavation process. However, the existing ventilation and dust control techniques can only control part of the dust created. If the dust is not controlled effectively, it can pollute a tunnel's working environment and have a serious impact on the health of construction workers. In this paper, the numerical simulation method is combined with field measurements to study the dust pollution diffusion law in a tunnel under different air suction volumes and where the suction ports are located at different distances from the cutter face. First, the diffusion law of dust pollution is simulated for different air suction volumes in a tunnel. Subsequently, the optimal air suction volume is used to further study the dust pollution in a tunnel under different suction port positions, and it is found that it is possible to control the dust created in a construction tunnel completely. The research results are then applied to the actual production process of construction tunnels, where the field measurements confirm that the diffusion of dust pollution is controlled completely during this process.

Comparison of dewaterability enhancement for river sediment by adding water transmitting channels in three dewatering procedures

The efficiencies of pressure filtration using air pressure (Air-P), suction (Suct-F), and filter pressing (Plate-P) were compared with and without the addition of water transmitting channels (WTCs). From the sediment, with initial water content of 60 ± 0.2 wt% and thickness of 5 cm, dry mud cakes with final water contents of 45.2 ± 0.1 wt%, 43.7 ± 0.1 wt% and 36.2 ± 0.4 wt% were obtained using Air-P, Suct-F and Plate-P respectively with 9 WTCs. The dewatering capacity increased by 100%, 200% and 100% compared to without WTCs. Layer water content analysis of the mud-cake after dewatering indicates that the WTCs added to the Air-P and Plate-P processes mainly enable filtration of free water from the upper layer, whereas the water in the middle and upper layer are sucked and filtered out through the WTCs during the Suct-F process. The water content of the upper layer decreased by 3.3%, 7.3% and 5.2% compared to without WTCs.

Analysis and Experiment on the Seed Metering Mechanism of Multi-Grain Cluster Air Suction Type Rice (Oryza sativa L.) Hill Direct Seed Metering Device

This paper aims to solve the problem of high reseeding rates and mis-seeding rates in the rice multi-grain hole direct seeding process. A multi grain cluster air suction type rice hill direct seed metering device was developed, and its seeding mechanism was analyzed. Based on CFD-DEM coupling simulation and bench tests, this study explored and optimized the performance of the seed metering device, and carried out the seeding adaptability test. The simulation results were as follows: when the negative pressure was −5 kPa, the static pressure, dynamic pressure and velocity of the flow field reached the maximum. When the negative pressure was −4 kPa, the qualification index was 89.62%, the reseeding index was 4.36%, and the mis-seeding index was 6.02%. The results of the orthogonal rotation combination test of three factors and five levels showed that when the rotation speed, negative pressure and the length of stirring brush were 20.70 rpm, −4.0 kPa and 10.50 mm respectively, the seed metering performance was the best, the qualification index was 90.85%, the reseeding index was 4.41% and the mis-seeding index was 4.74%. The seed metering device had strong adaptability to the sowing of different rice varieties, and met the agronomic requirements of direct seeding and seeding in rice holes.

MODELING OF THE PROCESS OF PRIMARY AIR SUCTION IN A HOUSEHOLD GAS BURNER ON BIOGAS FUEL

Statement of the problem. The process of suction of primary air into the housing of a gas burner device for domestic use during the combustion of gas fuel with different methane content in the composition is considered. It is necessary to develop a computer model of the movement of the gas-air mixture for a gas with a methane content of 50 to 90 % vol., with varying the height of the primary air regulator H from 0 to 19.25 mm and determine the concentration of O2 in the gas-air mixture at the outlet of the openings of the gas burner device, based on the results obtained, determine the rational dimensions of the primary air supply regulator. Results. The results of computer simulation of primary air suction by a flow of combustible gas inside the gas burner housing when using combustible gas with different methane content in the composition using the Ansys Fluent software package are presented. 3D modeling of the design of a gas burner equipped with a primary air supply regulator has been performed. The process under study was carried out by varying the methane content in the composition of the gas used and the height of the primary air regulator. The dependences of the oxygen content in the composition of the formed gas-air mixture on the composition of the combustible gas were determined, which made it possible to obtain the required dimensions of the primary air regulator.Conclusions. As a result of computer modeling, it was found that with a decrease in the methane content in the composition of the combustible gas, it is necessary to use a primary air regulator with a higher height H, which will ensure the suction of a smaller amount of primary air to ensure complete combustion of the combustible gas of the adopted composition.

Air Breathing and Suction Feeding Kinematics in the West African Lungfish, Protopterus annectens.

Research on the water-to-land transition tends to focus on the locomotor changes necessary for terrestriality. However, the evolution from water breathing to air breathing was also a necessary precursor to the invasion of land. Air is approximately 1000 times less dense and 50 times less viscous, and contains hundreds of times more oxygen than water. However, unlike the transition to terrestrial locomotion, breathing air does not require body weight support, so the evolution of air breathing may have necessitated smaller changes to morphology and function. We used X-ray reconstruction of moving morphology to compare the cranial kinematics of aquatic buccal pumping, such as that seen in suction feeding, with the aerial buccal pumping required for lung ventilation in the West African lungfish (Protopterus annectens). During buccal pumping behaviors, the cranial bones and associated soft tissues act as valves and pumps, and the sequence of their motions controls the pattern of fluid flow. Both behaviors are characterized by an anterior-to-posterior wave of expansion and an anterior-to-posterior wave of compression. We found that the pectoral girdle and cranial rib rotate consistently during air breathing and suction feeding, and that the muscle between them shortens during buccal expansion. Overall, we conclude that the major cranial bones maintain the same basic functions (i.e., acting as valves or pumps, or transmitting power) across aquatic and aerial buccal pumping. The cranial morphology that enables aquatic buccal pumping is well suited to perform air breathing and accommodates the physical differences between air and water.

Investigation of the Characteristics of Airfoils with Air Suction from the Upper Surface and a Given Pressure Distribution

Investigation of the Characteristics of Airfoils with Air Suction from the Upper Surface and a Given Pressure Distribution

Thermodynamics Analysis and Pilot Study of Reusing Medium and High Alloy Steel Scrap Using Induction Melting and Electroslag Remelting Process

The annual cumulative quantity of high and medium alloy steel scrap has exceeded 10 million tons. Using the traditional smelting process involving electric arc refining in a smelting furnace for these scraps causes high percentages of alloy losses, which decreases the value of the alloy steel scrap and poses environmental threats. Existing studies have rarely focused on separate smelting of the scrap and oxidation behaviors of the alloying elements. Therefore, this study proposes an induction melting and electroslag remelting scheme to process the scrap. Based on this scheme, the effects of the temperature, oxygen content, and element contents on the recovery percentages of the alloying elements were investigated using pilot experiment and thermodynamic analysis. The experimental results showed that the alloying elements (tungsten, chromium, nickel, molybdenum, and vanadium) exhibited recovery percentages of 97.36%, 94.62%, 97.63%, 95.09%, and 89.49%, respectively; furthermore, the impurity content did not increase during smelting. The thermodynamic analysis indicated that an increase in carbon content improved the oxidation resistance of the alloying elements except for nickel, whereas the increases in the contents of oxygen and alloying elements increase their oxidation. Steam partial pressure and air suction dramatically increase the concentrations of nitrogen, hydrogen and oxygen. This scheme is an alternative for smelting medium and high alloy steel scrap, and the thermodynamic analysis provides a theoretical understanding of the oxidation behaviors of the alloying elements in the steel scrap and the control of impurity.