Type Of Air Flow Research Articles

Density and Small Disturbance Equation-Based Simulation of Designed Bipalne Airfoil Under Supersonic Flow

For inviscid airflows, the small disturbance equation (SDE), as a condensed form of the full potential equation, is an effective approach for characterising the behaviour of this type of airflow in the presence of thin obstacles in its path. Density-based solutions (DBS) are frequently used by ANSYS to model the airflow behavior under the same environment. Through the impact of shock interference between the target wings, special Bussemann-type supersonic biplane designs can be effective in restricting sonic booms and wave drags in particular supersonic conditions. The modeling investigations of the shock oscillations produced between the wings are quite rare, nevertheless. Therefore, in order to replicate the behavior of the airflow over the target wing in supersonic settings and to compare the results more closely to reality, the Small Disturbance Equation (SDE) and the Density Based Solution (DBS) will be employed as efficient simulation tools in this study. The SDE results are vulnerable to inaccuracies because of the constraints of the simulation settings, whereas the DBS results are more accurate when compared to the exact simulation results. Overall, the DBS simulation results and the legit results are consistent, indicating that the inviscid airflow hypothesis is a feasible option for modelling the effectiveness of shock oscillations between wings. The SDE approach, which is implemented in Python and is a condensed version of the en-tire potential equation, offers a lot of space for development as it only does simulations in terms of velocity in this article and ignores the pressure and density elements.

Subject experiment on personal air-conditioning airflow using a vortex ring

A personal air conditioning system using vortex rings, which are characterized by their linearity and low diffusivity, is developed in this study. The authors have clarified the characteristics of the vortex ring airflow by LES (unsteady CFD) and full‐scale experiments. However, the airflow type and worker's comfort using vortex rings as an air conditioning system has not been clarified yet. As a result of the subject experiments, it became clear that air conditioning with vortex rings cooled the subjects better than conventional air conditioning and improved their sense of comfort with respect to the airflow. In addition, it was found that airflow to the neck was more effective since the subjects were less likely to feel the airflow at the top of the head due to the resistance of the hair on the head. The effectiveness of the vortex ring as a personal air conditioning system was clarified, enabling relaxation of the room temperature setting. The comfortability of the airflow sensation provided by the vortex ring was also examined when further airflow was given.

A study of airflow patterns among patients attending a hospital set up in Manipur

Background: Clinicians and surgeons often require instant knowledge of the lung function of their patients during the course of their management though they rely on the symptoms most of the time. Yet unexpected, abnormal respiratory airflow patterns are found in various diseases which affect the management whereas many respiratory complaints used to turn out to be normal. Respiratory symptoms often but not always correlate with airflow abnormality, thus making office spirometry an important tool for addressing these problems. Aims and Objectives: An evaluation of the profile of airflow patterns observed among patients attending regional institute of medical sciences (RIMS) hospital, Manipur, is carried out. Materials and Methods: The spirometry test performances of total 221 patients (120 males and 101 females) aged between 11 and 80 years sent from outpatient and wards of different departments of our hospital (RIMS Imphal, Manipur) were done after taking informed consents. The period of test performance was from June 2016 to November 2018 on all working days in the department of physiology. For this, a computerized spirometer (Helios model no. 401) was used. Results: 176 (79.6% of the total studied) patients presented with symptoms of respiratory diseases and after spirometry test, 121 (54.7% of the total) were having different patterns of abnormal airflow. About 60% of 111 patients complaining only of breathlessness are found to have normal lung function. Among 13 patients with a common disease such as chronic obstructive pulmonary disease, unexpectedly 2 cases of restrictive type of airflow and another 2 patients with normal airflow were found. Conclusion: Awareness of such altered and unexpected occurrence in lung spirometry epidemiology would be informative to the physicians in disease management.

Development of the airflow type photovoltaic system with solar shading effect

The number of zero energy buildings (ZEBs) with photovoltaic panels is on the increase. However, in high-rise building which has low ratio of roof area to total floor area, power consumption of the building exceeds electric-generating capacity of photovoltaic panels. For that reason, it is necessary to increase the solar panel area by installing photovoltaic panels on the wall or window. The purpose of this study is to develop the airflow type photovoltaic system with solar shading effect. First, we develop the external louver integrated with the photovoltaic panel which can generate power, recover heat from the panel, and block sunlight into the room. The external louver has holes at the top and bottom to cause natural convection inside the louver which cools the photovoltaic panel and improves the power generation efficiency of the panel. In addition, by taking warm air through the louvers into the room, the heating load of the building will be also reduced. Then, to verify the system, outdoor actual measurement was performed and compared with the non-airflow type photovoltaic system. As the result, ventilation rate through the louver was approximately 4.53 m3/h, and power generation efficiency of the airflow type photovoltaic system was increased 1.70 times than the non-airflow type one.

Forming and breaking the ceiling of inlet gas velocity regarding to separation efficiency of cyclone

The maximum-efficiency inlet velocity (MEIV) is a ceiling of inlet gas velocity that defines separation efficiency during cyclone design and operation. Experiment and computational fluid dynamics (CFD) simulation exhibited that an apex cone at the dust outlet can break the ceiling and improve the separation efficiency. The phenomenon is closely related to the effect of excessive high inlet gas velocity on the back-mixing escape of fine particles, which is the final result of back mixing, entrainment by the rapid upward airflow, and secondary separation of the inner vortex. In the center of the inner vortex, the airflow rotates slowly and moves rapidly upward. This elevator type of airflow delivers re-entrained particles to the vortex finder. A higher inlet gas velocity accelerates the elevator, causing more entrained particles to escape. This explains the decrease in efficiency at an excessively high inlet gas velocity. When an apex cone is installed at the dust outlet, the back-mixing is significantly weakened because the vortex core is bounded to the center of separator, while the transport effect of rapid upward airflow is weakened by the decrease in axial velocity in the center. Therefore, particle escape is weakened even at excessive high inlet gas velocities. Instead, the centrifugal effect is enhanced because of increased tangential velocity of the gas and particles. Consequently, the ceiling of inlet gas velocity is broken.

Smart composite using fibre optic sensors for fluid flow characterization and temperature measurement

The paper presents the results obtained in simulation of how air flow type over a wing surface, laminar or turbid, is detected using a Distributed Feedback Fibre Laser (DFB-FL) sensor or a Long Period Grating Fibre Sensor (LPGFS). A comparison of the two sensors is made. The air flow type over a wing surface is important for improving the “green flight” to a large as possible extent. The “green flight” with a reduced fuel consumption is assured by laminar air flow. The DFB-FL or LPGFS constitutes the feedback loop of the aircraft automatization having the optimisation of wing “attack angle” as a main parameter. The DFB-FL or LPGFS can be used for simultaneous system temperature measurements. The simulation results are compared with experimental ones and a good agreement between the two kinds of data being observed.

Optimal energy management for air cooled server fans using Deep Reinforcement Learning control method

The current study proposed the Deep Reinforcement Learning (DRL) AI control algorithm for energy-saving optimization in 1U air-cooled server mockup for different configurations and scenarios. The proposed algorithm can handle the server's complex thermal environment, including number of heat sources and their locations, type of heat sink, airflow, fan and bypass airflow. Based on the analysis and test results, it is found that controlling a single fan individually and the fans in different zones can offer the reduction of fan energy by 39–47% compared with the controlling all fans collectively. After the modification in observation characteristics, the fan usage rate was reduced by 45% compared with the single fan control model. Further, five different control models were developed and tested with experiments for different function variables and reward functions on three server configurations with different algorithmic settings for energy saving optimizations. The heat source of the three server configurations was close to the upper limit temperature and maintained stably by saving about 12% to 50% fan energy consumption. The algorithm can judge the system status and successfully provide real-time decision-making action thereby the energy consumption of the fan is significantly reduced.

Reverse hybrid jig separation efficiency estimation of floating plastics using apparent specific gravity and concentration criterion.

We developed a technique called the reverse hybrid jig, an advanced physical separation technique that combines the principles of jig and flotation to separate floating plastics. This technique is a promising green technology that is more economical and environmentally friendly compared with the conventional flotation. Although the applicability of this technique to separate PP/PE have been reported, the index to illustrate the possibility of separation for the reverse hybrid jig is still not available. In this study, a reverse apparent concentration criterion (CC RA ) is proposed to estimate reverse hybrid jig separation efficiency. This modified concentration criterion can be calculated using the specific gravity (SG) of particle with attached bubbles called the apparent specific gravity (SG A ). To determine the volume of attached bubbles on plastic surfaces under water pulsation, a laser-assisted apparatus was used under various conditions, including plastic type, air flow rate, dosage, and type of wetting agent. The results of attached bubble volume measurements were used to calculate the SG A and CC RA . The estimated values were then compared with the results of reverse hybrid jig separation. It was found that higher CC RA resulted in better separation efficiency. In addition, an empirical linear equation for estimating the reverse hybrid jig separation efficiency is proposed.

A Thunderstorm Gale Forecast Method Based on the Objective Classification and Continuous Probability

Potential prediction is an important research content of thunderstorm gale weather forecast, and it is still a challenge because the environmental field of thunderstorm gale presents different characteristics under different weather conditions. Using the 12-year thunderstorm gale data of Hubei province in central China and the reanalysis data of National Center for Environmental Prediction (NCEP), this study analyzed the percentile distribution of environmental physical quantities of thunderstorm gale, and the continuous probability method was adopted to establish the probability forecast models of thunderstorm gale in four different types of weather situation, which are in the rear of trough type, in front of trough type, in the periphery of the western Pacific subtropical high type and easterly airflow type. Finally, probability prediction was realized by objective classification criterion in operation. The results show that the method based on objective classification and continuous probability can significantly improve the probability of thunderstorm gale detection, and also reduce the missing alarm rate of thunderstorm gale. Moreover, the quantitative test of 16 weather processes under four types of weather situations also shows that the continuous probability method has a higher probability of detection than the bisection method, and significantly reduces the missing alarm of extreme wind by the bisection method.

The Positive and Negative Synergistic Airflow-Type Jujube Fruit Harvester (P-N JH)

Low operation efficiency and poor working performance are the main reasons that restrict the application of pneumatic date pickers. In this study, it is proposed to use positive pressure air flow blowing and negative pressure air flow suction to pick jujube fruit and to use inertia air flow to remove impurities and design a positive and negative collaborative air flow type date fruit harvester (P-N JH). The second-order regression model of test factors and response indexes was established by using the central composite design method, and the operating performance of P-N JH was evaluated and comprehensively optimized, and the optimal combination of operating parameters was obtained: positive pressure wind speed, negative pressure wind speed, and travel speed were 16.8 m·s−1, 34.0 m·s−1, and 1.5 m·s−1, respectively. In addition, the verification test results show that the pickup rate, impurity rate, damage rate, and operating efficiency are 97.21%, 2.15%, 1.08%, and 2170 kg/h, respectively. The operating performance of P-N JH not only meets the requirements of jujube picking but also significantly improves the operating efficiency compared with the traditional air-suction jujube harvester. This study can provide theoretical and technical reference for the harvesting of air-suctioned dates; it also provides a new way of thinking for jujube fruit picking.

Kinerja bom kalorimeter sebagai alat ukur nilai kalor bahan bakar

The calorific value contained in the fuel is one of the benchmarks for the quality of the fuel. To test the calorific value of fuel, a test device such as a bomb calorimeter is needed. The performance of the calorimeter bomb is influenced by the heat absorbed by the water media and the heat wasted into the environment and the heat from the combustion that occurs in the combustion chamber (reactor). Combustion in a bomb calorimeter is affected by the rate of air flow used. The wasted heat to the environment can be minimized by using an insulator on the outer wall of the calorimeter bomb. The purpose of this study was to determine the effect of air flow rate and type of insulator on combustion temperature, heat transfer and accuracy of bomb calorimeter test results. The method used in this research is experimental research by making and testing bomb calorimeters using variations in the air flow rate in the combustion process, namely 40 m/s, 50 m/s and 60 m/s and the types of insulators are air and Fiber glass wool. From the results of the research that has been done, it can be concluded that the air flow rate and the type of insulator affect the combustion temperature, heat transfer and accuracy of the bomb calorimeter. The maximum combustion temperature is 480 °C to 490 °C, heat transfer is 77.7 watts and the highest bomb calorimeter accuracy is 98% obtained at variations in air flow rate of 60 m/s and Fiber glass wool insulator.

Differential Pressure Changes of a High Airflow–Type HEPA Filter During Solvent Fire in Reprocessing Facilities

A clogging behavior of a high-efficiency particulate air (HEPA) filter has been investigated for solvent fire accidents to provide valuable data for establishing a risk assessment method for reprocessing facilities in Japan. In this study, the burning rates of 30% tri-butyl phosphate (TBP)/dodecane and dodecane solvents and the differential pressure ΔP change of a high airflow–type HEPA filter applied in ventilation systems of reprocessing facilities in Japan were measured in the solvent burning. It was confirmed that the dodecane in the 30% TBP/dodecane mixed solvent burned mainly at the early stage of the burning of the mixed solvent and that the TBP burned mainly at the late stage of the burning of the mixed solvent. In addition, the burning rate of dodecane in the early stage and the rate of the TBP in the late stage were estimated, respectively. As a result, the former rate was almost the same as the burning rate of burning only the dodecane without TBP. Furthermore, the rapid increase of the ΔP of the HEPA filter was observed at the late stage of burning the mixed solvent. The increase of the release ratio of the airborne particles of unburned solvent (i.e., TBP and/or degradation products of TBP) and inorganic phosphorus (i.e., P2O5) was considered to contribute to the rapid increase. The empirical formulas for representing the relationship between the mass of the loading airborne particles onto the HEPA filter and the ΔP of the HEPA filter, except for the region of the rapid increase of the ΔP, under the mixed-solvent burning could be induced.

Deposition patterns around buildings at the beach: Effects of building spacing and orientation

Airflow at the beach creates sand deposition patterns around buildings. To assess how initial deposition patterns depend on the orientation of a building relative to the wind direction and on the spacing between buildings, a series of one-day field experiments was conducted with cuboid scale models, in which 34 configurations were tested. Scale models placed further apart than 2 to 3 times the building width created deposition patterns that were similar to those for stand-alone buildings, where downwind deposition tails were the sum of the individual buildings' effects where these overlapped. For smaller spacings, between 0.5 and 2 times the building width, deposition patterns fundamentally differed from those for individual buildings, indicating a different type of airflow developed between the buildings. This created more complex depositional patterns that depended on the gap width. Rotation of an individual building relative to the wind direction induced an asymmetry in the downwind deposition patterns. A new rule of thumb quantitatively relates the asymmetry in the length of the deposition tails behind a building to the angle of the wind relative to the building and the length:width ratio of the building.

Effect of environmental and behavioural factors on microbiological air quality of operating rooms

Introduction: An operating theatre (OT) is a very complex setup, which presents numerous challenges for both patients and health care providers. A safe OT environment decreases the susceptibility of patients to postoperative infections. Therefore, a study was conducted to determine microbiological air quality for establishing baseline values and to assess concurrently the effect of environment and behavioural factors in 46 OTs of a tertiary care hospital. Materials & Methods: The OTs were divided into two groups based on the type of air flow: laminar diffuser (Group I) or conventional diffuser (Group II). Two hundred and thirty-eight samples were collected with an active technique using a sieve impactor, sampling at 100 L/minute. Statistical analysis was conducted using Statistical Package for Social Sciences (SPSS) Version 20 (IBM Corp., Armonk, NY). Results: In Group I OTs with the laminar diffuser, bacterial and fungal values during the lean period for environmental and behavioural factors were 47.78 colony forming units (CFM)/m3 and 0.24 CFU/m3, respectively. The bacterial and fungal values during the surgical period were 98.01 CFU/m3 and 0.40 CFU/m3, respectively. The same values for Group II OTs with the conventional diffuser were 52.83 CFU/m3 and 0.39 CFU/m3 during the lean period, and 80.06 CFU/m3 and 0.40 CFU/m3 during the surgical period. Discussion: Both environmental and behavioural factors – temperature, humidity, percentage of fresh air in circulation, door type, controlled entry, minimal door opening and proper OT attire – were seen to contribute concurrently to maintaining air quality in operating units.

Air drag coefficient of textile-covered elastic cylinders – preliminary aerodynamic studies

This paper presents preliminary experimental results on the influence on the aerodynamic drag of a cylinder from the cylinder type (i.e., rigid or soft) and its textile surface. Both a rigid cylinder and a soft-body cylinder, with a gelatin layer, each with five different textile surfaces were measured in the wind tunnel using force measurement technology. The drag coefficient was determined for several Reynolds numbers. The study shows that the elasticity of a cylinder has a significant influence on the drag force and the airflow type. However, the influence of the soft-body cylinder depends on the respective fabric. With the given measurements, no exact statements can yet be made to quantify the influence. This influence must be studied independently and in conjunction with the textile surface in order to gain understanding of the overall system of airflow, textile and elastic body.

Thermal analysis of solar air collectors designed in different types with different flow rates using aluminum cans

ABSTRACT In this study, an air solar collector (SAC) was compared in three different ways (flat plate, serial connection, and parallel connection) using aluminum Coke cans according to the conditions of the region. Experiments were conducted at an air speed of 3 m/s to 6.5 m/s. Data were compared with each other according to two different air flow rates with three different flow forms. As a result of the experiments, the highest temperature difference in the measurements made at 3 m/s air speed was 68°C in the Parallel Collector and 56°C of the serial collector at 6.5 m/s air speed was observed. According to the results, when the system was operated at 3 m/s, it was seen that parallel collector provided good results, and when it was operated at 6,5 m/s, it was seen that serial collector yielded good results. At the end of this study, it is possible to conclude that choosing the proper air flow type can be applicable in terms of energy efficiency in order to increase the efficiency of the collector. Abbreviations: Td: Outside temperature (oC); Tg: Collector inlet temperature (oC); Tç: Collector outlet temperature (oC); IT: The amount of radiation incident on the collector surface (W/m2); η: Collector efficiency (%); V: Air speed (m/s); ṁ: Mass flow rate of air passing through the collector (kg/s); W: The total power consumed for the heating system (W); Wfan: Fan power (W); Ød: Outdoor relative humidity (%); Øi: Indoor relative humidity (%); Qu: Usable energy from the collector (W); Cp: Specific heat of air at constant pressure (kJ/kgoC); ρ: Density of air (kg/m3); Ak: Collector area (m2); Aç: Collector outlet cross section of air (m2); MW/m2: Per square meter MegaWatt; W/m2: Per square meter Watt; W/mK: Watt/meter Kelvin; SAC: Solar Air Collector; CFD: Computational Fluid Dynamics; SAH: Solar Air Heater; d: Outside; g: inlet; ç: outlet; i: Indoor; u: Usable; k: Collector.

Performance Analysis of a Small-Sized Screw Cooling Tower

In this Article describes analysis of efficiency, i.e. analysis of coefficient of thermal - and mass transfer, which carried out thanks to increase of time of phases interaction in developed cooling tower with a spiral air flow. There is given a description of the construction of effective the small-size cooling tower with the spiral type airflow. The main difference of the cooling tower of the existing constructions of that the sprinkler, made of layers of cylindrical polymer cellular pipes, laid on screw line, alignment to the current of the screw type airflow. The small-size cooling tower operates as following: the water, heated at technological process from the closed loop of system is brought to water distribution system. It is distributed evenly on all square of the sprinkler laid on the screw, in which take place a heat and mass transfer of the water and air spiral type flow, which is create by the fan. There is a swirling of the gas phase the tangential feed of the cooling air flow in the bottom of the cylindrical small-size cooling tower, and it can be described by two elements of speed: rotational and translational. Such action allows to intensify a heat and mass transfer processes.

Drag induced aerodynamic braking for racing motorcycles

Winglets are small aerodynamic structures attached to the front fairing of a racing motorcycle to increase traction. It increases the control of the rider and maneuverability while accelerating as it reduces the event of front wheel lift. This paper discusses the speed of the motorcycle and braking force given by the rider. Based on the inputs it would change the orientation of the winglet which would produce a drag force on the bike and increases the rate of deceleration. CFD simulation is performed by STARCCM + software with unstructured polyhedral mesh and AKN k-ε turbulence model is used on the winglet surface with different orientations (0 and 90 degree) to find the type of airflow that creates optimum drag and maximum pressure, in which winglet can withstand without being damaged. The procedural way of numerical approach and it results may provide design assistance for the improvement of the aerodynamic winglets for racing motor vehicles.

A comprehensive review of experimental investigation procedures and thermal performance enhancement techniques of solar air heaters

SummaryThis review composition aimed to comprehensively present the experimental investigation procedures and thermal performance augmentation techniques of solar air heaters. Various testing standards such as static and dynamic tests, and performance parameters, such as, thermal, thermo‐hydraulic, and exergy efficiencies, are incorporated to present the experimental investigation procedures. The present review work deals with testing conditions (indoor and outdoor), instrumentation, various parameters of interest with corresponding optimum values, their uncertainty levels together with SAH orientation, air flow type, thermal energy storage devices, duct modifications and heat transfer surfaces using fins, baffles, and ribs employed to enhance the thermal performance. The authors of this review work believed that the current composition constitutes a summary of details to quickly access the information for analyzing the various experimental investigation procedures and heat transfer augmentation techniques along with the optimum values of flow and geometric parameters. Moreover, economical and efficient solar air‐heating systems with low pressure drop and high heat exchange to air are presented and reviewed.

2DOOR REFRIGERATOR NEW PRODUCT DEVELOPMENT ANALYSIS BY USING QFD METHOD: A CASE STUDY REFRIGERATOR PRODUCT IN INDONESIA

This study aims to find out the features of a 2-door refrigerator product that suitable the needs and desires of consumers at this era. The need and ever-growing desire for refrigerator products is not just to condition food or drinks or other goods so that the condition remains fresh or controlled at a certain temperature. The method used is Quality Function Deployment (QFD) by capturing customer voice (VOC). With this method the consumer voice obtained is then translated into product technical requirement in the development of new products. In this study the products studied were 2-door refrigerator products types that were suitable for the needs of consumers with a small number of families with consumer routines activities. The results of the study it was found that, there are 3 big points of the 2-door refrigerator products that consumers want that rapid freezing time, low prices, and low electricity consumption. To achieve this requirement, the fabrication company carries out air flow type modification, efficiency production cost, material usage and use of special components to get efficient energy products.