Analysis Of Airflow Research Articles

Analysis of Airflow in Corridors, Staircases, and Voids using Exhaust Fans

Analysis of Airflow in Corridors, Staircases, and Voids using Exhaust Fans

AIRFLOW ANALYSIS OF HUMAN RESPIRATORY SYSTEM AT DIFFERENT PHYSIOLOGICAL CONDITIONS

In this paper, an attempt has been made to analyze the effect of different physiological conditions i.e., rest, moderate and extremely active on the branch Reynolds number, pressure drop, lost work, alveolar partial O2 pressure, airway resistance and surface tension. From the analysis, it has been observed that local Reynolds number and tracheal pressure drop along with the generations of branch. The alveolar O2 pressure and surface tension decrease with the increased activity level. Work lost due to different major and minor losses in the respiratory tract increases with the increase in activity level. A similar trend was also found for the airway resistance i.e., increases with the increase in activity level. A new parameter, Breathing Work Number (BWN) in respiratory mechanics is introduced. BWN is the ratio of the work of breathing to the sum of work of breathing and work loss, which might find a significant application to denote the respiratory health. From the analysis, it is found that BWN decreases with the increase in activity level.

A GAN-Based Surrogate Model for Instantaneous Urban Wind Flow Prediction

Urban form impacts the airflow patterns in cities and the resulting urban microclimate. This has significant implications for ventilation, overheating, wind chill, and safety concerns such as down drafts from skyscrapers. While Computational Fluid Dynamics (CFD) simulations are the best practice for analyzing urban airflow patterns in design, they are computationally expensive and require a high level of expertise, making them underutilized in the early design process. This paper presents a surrogate model for CFD using a Generative Adversarial Network (GAN) that can process arbitrary building geometries. The model is trained using an automated end-to-end pipeline based on Eddy3D and implemented within the Rhino and Grasshopper environment as an Open Neural Network Exchange (ONNX)-based CFD-GAN predictor. This workflow provides instantaneous simulation feedback within the design software, reduces the risk of user error, and allows for appropriate spatial resolution in early design. The CFD-GAN demonstrates promising accuracy, with a Structural Similarity Index Measure (SSIM) ranging from 75%–97% on a limited training dataset of 564 unique urban geometries. Although the model currently has limitations regarding accuracy in complex urban wake regions, we show that these are likely not of concern for outdoor thermal comfort analyses. While it cannot replace CFD in later design stages, the CFD-GAN facilitates the incorporation of urban airflow analysis in early design with minimal effort and instantaneous performance feedback.

Tri-Rotor Propeller Design Concept, Optimization and Analysis of the Lift Efficiency During Hovering

This study introduces the simulation of a tri-rotor contra-rotating propeller for thrust force and hover lift efficiency during vertical take-off. Vertical take-off or landing is a method used by many aircraft and makes the vehicle more convenient and easier to use. The second rotor revolved in the opposite direction of the first and third rotors. The proposed multi-rotor system has NACA 0012 untwisted and symmetric airfoil and includes three rotors with two blades for each. The airflow analysis was optimized with computational fluid dynamics simulation by using different pitch combinations to achieve the highest hover lift efficiency with sufficient overall thrust value. The critical angle of attack for the chosen airfoil gave the boundary conditions for the pitch of rotors. The results showed us that the most efficient combinations for three rotors work better with an increase of pitch angle from top to bottom so that there is a difference of at least two degrees between propellers. Experiments with angles of attack within the boundary conditions showed that the blade combinations starting from three degrees and increasing values gave positive and adequate results in many cases. In addition, the results showed that a regular increase in the angle of attack does not relate to a regular increment in thrust force.

Possibilities of 3D laser scanning data utilization for numerical analysis of airflow in mining excavations

Underground mining of deposits is strongly dependent on several key processes enabling its safe operation. One of these processes is mine ventilation aimed at supplying an appropriate amount of air with a specific chemical composition, diluting harmful gases generated in technological processes and emitted from the rock mass, and ensuring appropriate climatic conditions at workplaces. For all that mine ventilation has strategic importance and is responsible for 30-40 % of overall mine operation costs. A very important task is to conduct calculations and simulations to determine the airflow in ventilation networks, both existing and planned in the future, along with the progress of the mine operation. In the era of the development of modern technologies, new perspectives for changing the current approach to the design and optimization of ventilation networks are available. Their utilization may contribute to accuracy improvement, which can drive safety increases and process optimization. In this article, the authors evaluate the possibilities of using laser scanning data, collected with LiDAR / Terrestrial Laser Scanner, to generate 3D models of underground structures geometry, and its further utilization to conduct numerical simulations of airflow in mining excavations with Computational Fluid Dynamics. The performed analysis shows that the proposed approach may be a useful instrument for analyzing local airflow phenomena, particularly in complex ventilation networks, where disturbances in air velocity vectors are caused by sudden changes in geometry.

Air Flow Analysis for Protective Clothing Ventilation Elements with and Without Constant Cross-Section Area Opening

Abstract In this paper a ventilation element is designed with the constant cross-sectional area of 3.14 mm2 with the outer ring, to study the efficiency of ventilation at three different inlet air velocities (2, 5 and 8 m/s). There are five different cases analysed in the study, in which four cases are with different coordinate values of outer ring and core while the fifth case is studied with ventilation element without outer ring. The results of all five cases are analysed and compared to see the efficiency of ventilation element design. These ventilation elements are attached at ventilation hole at the inner part of the protective jacket. The attached ventilation element increases mechanical strength of the clothing by covering ventilation hole and restricting direct access of insects to the body. Moreover, ventilation elements permit smooth flow of air inside jacket. The objective is to determine which element’s geometrical configuration results in the minimum flow energy losses in the cell flow channel from the inlet to the outlet, which are represented by the pressure difference. Flow energy losses increase with increasing pressure difference (ΔP), and the body cooling reduces if the flow is weakened or there is of lost energy. SolidWorks Flow Simulation is used to calculate the pressure, temperature, and heat flux for the simplified elliptical model of the human body with a protective jacket. The obtained results are compared and analysed to study the concept of constant cross-sectional area in the design of ventilation elements with and without outer ring. The pressure and temperature difference for each case are calculated for the comparison and the obtained results show that the element design without outer ring provides better overall results and less flow energy loss in the cell flow channel than that of element design with outer ring.

Experimental Exergy Analysis of Air Flow Through Micro Helical Tubes with Novel Geometries under Adiabatic Conditions

Helical microtubes are commonly used in micro-electronic cooling techniques and micro-heat exchangers because of the creation of secondary flows, which leads to greater temperature and velocity gradients. It is of great significance to further improve the overall efficiency of the helical microtubes so as to diminish energy consumption. This experimental work mainly focuses on exergy analysis of air flow through adiabatic helical microtubes with circle, triangle, square, and pentagon geometries with circular cross section. The temperature rises due to viscose dispassion and pressure drops have been measured for all adiabatic helical coils in the laminar flow range. To identify irreversibility of flow, rate of air flow, coil diameter and Dean number are varied to investigate their influences on the entropy generation. Also, the second law of thermodynamics was applied to recognize exergy efficiencies and to determine true magnitudes of exergy losses. Results indicate that entropy generation increases by increasing the flow rate and the coil diameters in all geometries, however, the exergy efficiency decreases. By considering geometry, in constant flow rate and identical coil diameter, the highest entropy generation can be approximately observed in the triangles, squares, pentagons, and circles, respectively. Moreover, the proportions of theoretical exergy losses to actual exergy losses have been computed for all geometries in order to probe the viscous heating effects and it is found that the predicted exergy losses distinguish substantially from measured amounts due to viscose dispassion.

Detailed Analysis of Airflow Generated by High Voltage on a Point-Tube Electrode Geometry

This paper is focused on the research of airflow generating through the use of high-voltage electrohydrodynamic devices. For this purpose, the authors built several electrohydrodynamic airflow generators with one point electrode and one tube electrode of varying dimensions and compared their efficiency in generating the airflow in order to find an optimal design. The character of the flow was also analyzed with the help of particle image velocimetry, and velocity vector maps and velocity profile were acquired. In addition, a possible practical cooling application was proposed and realized with positive results. Lastly, the products present in the generated airflow were tested for ozone and nitrogen oxides, which could have detrimental effects on human health and material integrity. In both cases, the concentration has been found to be below permissible limits.

Experimental and numerical research of backfill cooling based on similarity theory

Based on the similarity theory, this paper conducts a dimensionless analysis of air flow and selects Archimedes number as the similarity criterion number in order to study the cooling effect of mine cold storage backfill under ventilation environment. The similarity experimental platform has been built through collecting actual stope parameters and determining the geometric and velocity scales. The influence of different backfill cooling methods and air supply conditions on the temperature distribution of stope has been studied both by similarity experiment and CFD numerical simulation. Through model verification, it is proved that Archimedes number is suitable as the similarity simulation criterion number in this research and the similarity method is feasible to predict the parameters in prototype. The results show that ventilation alone often fails to meet the specified cooling requirements in deep mine, and cold storage backfill is an effective method to control the temperature in stopes. Compared with the upward backfill method, the downward backfill method is superior in terms of cooling temperature and cooling duration. Because the position of the air supply outlet is close to the top of the stope, the ventilation has a great influence on the cooling effect of the downward backfill, and the excessive wind flow reduces the cooling effect. Furthermore, ventilation accelerates air convection, which makes the flow field in the stope unstable, and leads to horizontal temperature difference in logistic distribution.

Experimental Study of an Industrial Tower-Type Supporting Frame with Facades Subjected to the Stationary Wind Effect

Aerodynamic studies of canceled structures are important for design of buildings, analysis of air flows inside buildings, evaluation of buildings’ effects on air flow patterns of the adjoining area, and optimal choice of enclosing structures. The analysis of wind effects during the design of canceled structures is governed by codes and standards of general purpose. These statutory documents do not regulate the mounting procedure of wind protection screens, nor do they contain the analysis of wind effects on structures with different angles of attack of an incident wind flow. The codes prescribe aeroelastic model testing in special civil engineering wind tunnels during the design of such structures. The purpose of this research project is to analyze wind effects on the force and torque specification of a canceled structure at different wind effect angles accounting for the mounting sequence of wind protection screens. The subject of the article is an experimental aeroelastic study of wind effects on a canceled structure accounting for sequential mounting of wind protection screens on the structure’s facade. The obtained data will allow for the analysis of effects of the wind flow angle on internal forces of the structure, given that a change in its permeability is taken into account. At the initial design stage, experimental modeling of wind effects in a wind tunnel is thereby considered a structure model validation step. The relevance of the paper lies in the need to identify optimum operating conditions of canceled structures, subjected to a wind effect, to ensure safe and comfortable work of people and reliable operation of process equipment installed inside the facility.

Fluid-structure interaction analysis of airflow, structural mechanics and aerosol dynamics in a four-generation acinar model

Elucidating the aerosol dynamics in the pulmonary acinar region is imperative for both health risk assessment and inhalation therapy, especially nowadays with the occurrence of the global COVID-19 pandemic. During respiration, the chest's outward elastic recoil and the lungs' inward elastic recoil lead to a change of transmural pressure, which drives the lungs to expand and contract to inhale and expel airflow and aerosol. In contrast to research using predefined wall motion, we developed a four-generation acinar model and applied an oscillatory pressure on the model outface to generate structure deformation and airflow. With such tools at hand, we performed a computational simulation that addressed both the airflow characteristic, structural mechanics, and aerosol dynamics in the human pulmonary acinar region. Our results showed that there is no recirculating flow in the sac. The structural displacement and stress were found to be positively related to the change of model volume and peaked at the end of inspiration. It was noteworthy that the stress distribution on the acinar wall was significantly heterogeneous, and obvious concentrations of stress were found at the junction of the alveoli and the ducts or the junction of the alveoli and alveoli in the sac. Our result demonstrated the effect of breathing cycles and aerosol diameter on deposition fraction and location of aerosols in the size range of 0.1–5 μm. Multiple respiratory cycles were found necessary for adequate deposition or escape of submicron particles while having a negligible influence on the transport of large particles, which were dominated by gravity. Our study can provide new insights into the further investigation of airflow, structural mechanics, and aerosol dynamics in the acinar depth.

Experimental and numerical analyses of airflow around two cylinders angled to the direction of wind

Experimental and numerical analyses of airflow around two cylinders angled to the direction of wind

Air Quality Improvement in COVID-19 Pandemic: Numerical Study of ventilation system in a classroom

Air quality plays a significant role during the coronavirus pandemic. Air acts as a spreading media as well as a control measure for infection in polluted spaces. Insufficient ventilation around the building may lead to a rise of pollutants carrying the virus. One way to improve ventilation is by increasing the air change rate. This study investigates the air change rate effectiveness in reducing droplets spreading in a classroom. Cases with various layouts of inlet and outlet vents are considered, and the spread of droplets is studied. The airflow analysis shows the impact of the different ventilation layout configurations. The results show that the CFD model simulation indicates an optimum ventilation configuration to decrease the droplet spread. The discrete phase model results also determine the trajectory of droplets spread along the classroom. CFD results show that in the selected configuration, a significant number of droplets are expelled to the outside and reduce their concentration inside the classroom.

Effects of six sigma implementation on occupational health and safety in industrial diesel engine production and maintenance processes

This study researched the results of implementing the Six Sigma approach to occupational health and safety in the Diesel engine industry in Europe. Six Sigma is a robust philosophy used in manufacturing industries to improve production processes, reduce risks, and enhance quality. It also aims to prevent work accidents and create a safer working environment by eliminating process faults. Employers must prioritize employee protection and a healthy working environment, and the Six Sigma methodology offers opportunities to achieve this. The study focused on the accident and injury types and amounts of one of the industrial Diesel engine production and maintenance companies operating worldwide. Occupational accident statistics were used between 2019-2022 as data. The path taken in occupational health and safety with Six Sigma in these three years was examined. In order to be able to decide on changes in health and safety conditions, the company's analysis of air-flows and heat transfer using the exhaust gas temperature in a project aimed at optimizing workplace temperature control is exemplified.

Analysis of Selected Hazards and Working Environment Factors: The Case of a Production Plant in Poland

The analysis of the working environment factors is an extremely broad topic, especially as each enterprise is characterised by a different safety management system and the presence of various risks. Due to the specific nature and profile of manufacturing or service companies, as well as the different working processes, more attention is paid to physical, chemical or psychophysical risks. This paper presents the results of a study on the measurement and analysis of temperature and airflow at a selected workstation and an analysis of the risks involved.

Numerical Analysis of Airflow in a Solar Collector with Zigzag Absorber and Modified Passage Section

Numerical Analysis of Airflow in a Solar Collector with Zigzag Absorber and Modified Passage Section

Thermal performance and airflow analysis of a new type of Double Skin Façade for warm climates: An experimental study

Double Skin Facades (DSF) integrated with shading devices are increasingly implemented in tall buildings to protect the building from excessive solar radiation. However, the potential overheating of DSF in warm climates leads to lower DSF performance in hot seasons. In this study, a new type of DSF named Interstitial Slat-blind DSF (IS-DSF) has been introduced featuring wind-induced ventilation and insulated shading devices. This research aims to highlight the capabilities of the proposed DSF in a warm climate and identify contributing environmental and geometrical factors for overheating risk reduction of IS-DSF. To this end, an experimental study was conducted in a scaled room located in an outdoor environment on summer days in Brisbane, Australia. First, the test room with and without IS-DSF was studied to assess the performance of IS-DSF for controlling indoor temperature. Next, a parametric evaluation was conducted including geometrical variables (cavity width, slat blind angle) and environmental factors (approaching wind speed and direction, air velocity in the cavity and solar radiation). It was found that the most influential factor for controlling the cavity overheating risk is the air velocity inside the cavity while the effect of blind slats angle is negligible. A cavity airflow velocity threshold was estimated beyond which the overheating of the IS-DSF cavity becomes negligible. Correlations were established to predict cavity airflow velocity from approaching wind speed for IS-DSF with different lateral openings. Overall, IS-DSF showed a reduction in surface temperature of the cavity as a potential advantage compared to conventional DSF to reduce the overheating risk of the DSF's cavity in a warm climate. • Addressing the overheating risk of Double Skin Facade (DSF) in warm climates. • IS-DSF is introduced featuring vertical openings and insulated shading devices. • An air velocity threshold for overheating estimation is experimentally identified. • Correlations are established to predict the air velocity in DSF's cavity.

One Bad Apple Can Spoil the Bunch: The Impact of Contamination in the Clinical Laboratory.

Laboratory contamination is a relatively broad, diverse, and often overlooked concern in the clinical laboratory. All clinical specimens have the potential to harbor infectious disease such as HIV and pose a potential risk to laboratory workers. However, the term “laboratory contamination” also encompasses the potential impact of the laboratory on the analysis of a specimen. For example, contamination may be introduced by laboratory staff or from carryover from another specimen. As a result, laboratory contamination may have serious and widespread negative impacts on both diagnostic testing and laboratory staff. With regards to testing, if not identified early, the impacts can extend far beyond an individual patient’s sample, possibly jeopardizing the integrity of a multitude of patient samples and instruments. Despite routine quality control (QC) procedures, the number and types of contamination events in the clinical laboratory are unknown and generally not reported. Further, investigation into the source of contamination can be time and cost intensive, involving methods such as precision studies, instrument service and replacement of parts, airflow analysis, assessing water purification systems, environmental dust sampling, and development of methods for monitoring and cleaning. Measures to decontaminate the laboratory and impacted equipment are both cost and labor intensive. Despite this, there is limited data in the available literature regarding procedures for effective decontamination.

Nasal airflow patterns in a patient with septal deviation and comparison with a healthy nasal cavity using computational fluid dynamics

Background and objective: Causes for nasal airway obstruction (NAO) are many but septum deviation is the most prevalent etiology. A deviated septum affects the airflow dynamics in the human nasal cavity, which in turn affects the physiological functions of the nasal cavity like heating, humidification, and filtration capabilities. The present study investigates and compares the airflow patterns in a healthy nasal cavity to a septal deviated nasal cavity.Methods: Two nasal airway models are considered and compared in this study. One with a septal deviation and the second with a healthy patent nasal cavity. Airflow analysis is carried out by developing the CT scans into 3D models using Materialise MIMICS (Materialise, Ann Arbor, MI), and then using the FLUENT solver of ANSYS 2020R2. The simulations are carried out for airflows ranging in laminar and turbulent flows using the SST k-ω turbulence model. Polyhedral meshes are used and the mesh check using Grid Convergence Index studies is adopted.Results: The pressure and velocity profiles are assessed for a wide range of mass flow rates. The results indicate a turbulent flow pattern for mass flow rates over 15 LPM. The velocity profiles show aberrated flow profiles in a septal deviated nasal cavity where the peak velocity is observed at the mid-nasal region rather than the nasal valve region. There was a 38% to 55% higher nasal resistance in the septal deviated nasal cavity as compared to a normal and healthy nasal cavity. The pressure drop in the septal deviated nasal cavity is higher by 60%–120% when compared to a healthy nasal cavity.Conclusion: The septal deviated nasal cavity greatly affects the nasal airflow distribution resulting in higher velocities in the mid-nasal region, increased pressure drop and higher nasal resistance. Hence the NAO with septal deviation has to be rectified with proper surgical procedures.

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.