Average Air Speed Research Articles

Experimental investigation on the separation and cleaning efficiency of pea & lentil split chaffs using cyclone cleaner

Cereal grains like pea & lentil split are the principal component of human diet in Ethiopia. But the separation process is very exhaustive and disturbing for the environment since it is used traditional separation. To design an effective separator machine, experimental testing is carried out in a cyclone with body diameter of 0.25 m to determine the efficiency of pea & lentil split grain-chaff separation and cleaning. The average speed of inlet air used for better separation minimizing grain loss is measured using Mini Digital Anemometer at different speed of fan motor by controlling motor speed controller device. In this test, the average air speed of 10.3 m/s and 9.4 m/s are measured for better separation with separation efficiency of 99.03 % & 99.37 % and cleaning efficiency of 99.02 % & 99.07 % for pea and lentil split chaff separation respectively within 1 % of loss.

Dispersion of artificial tracers in ventilated caves

Artificial CO2 was used as a tracer along ventilated karst conduits to infer airflow and investigate tracer dispersion. In the karst vadose zone, cave ventilation is an efficient mode of transport for heat, gases and aerosols and thus drives the spatial distribution of airborne particles. Modelling this airborne transport requires geometrical and physical parameters of the conduit system, including the cross-sectional areas, the airflow and average air speed, as well as the longitudinal dispersion coefficient which describes the spreading of a solute. Four gauging tests were carried out in one mine (artificial conduit) and two ventilated caves (natural conduits). In this paper, we demonstrate that it is possible to gain reliable airflow rates and geometric information of ventilated karst conduits using CO2 as a tracer. Airflow was gauged along two caves and one mine and compared with punctual measurements made with a hot-wire anemometer. Cross-sectional areas estimated with CO2 tests were compared with those measured in situ. Moreover, breakthrough curve (BTC) analysis displayed an accentuated tailing along the investigated natural conduits due to the presence of dispersive singularities which possibly enable aerosol deposition. The long tailing observed in Milandre and Longeaigue Caves is probably due to cross-section variations. A 1-D advection-dispersion model tested for these sites was unable to fit BTC tailing in natural conduits. In Baulmes artificial conduit, where long tailing is not observed, the dispersion coefficient has been estimated using Chatwin’s method, and compared with the prediction of Taylor’s theory. Despite the regular geometry of Baulmes Mine, Taylor’s correlation significantly underestimates the dispersion coefficient deduced from field data, showing the need for more theoretical work on turbulent dispersion in mines. This paper gives a first insight into air motion and matter dispersion along ventilated karst conduits, preparing for proper aerosol dispersion modelling.

DRONE-BASED CROP TYPE IDENTIFICATION WITH CONVOLUTIONAL NEURAL NETWORKS: AN EVALUATION OF THE PERFORMANCE OF RESNET ARCHITECTURES

Abstract. This study investigates the application of deep learning techniques, specifically ResNet architectures, to automate crop type identification using remotely sensed data collected by a DJI Mavic Air drone. The imagery was captured at an altitude of 30 meters, maintaining an average airspeed of 5 m/s, and ensuring a front and side overlap of 75% and 65%, respectively. The pre-flight planning and image acquisition was facilitated through the Drone Deploy platform, yielding a dataset consisting of 1488 aerial photographs covering the study area. These images possess an average ground sampling distance (GSD) of 22.2 millimetres. The dataset was meticulously labelled with "maize" and employed to train three distinct ResNet architectures, namely ResNet-50, ResNet-101, and ResNet-152. The evaluation of these models was based on accuracy and processing time. Notably, ResNet-50 emerged as the most proficient, achieving an accuracy rate of 82% with a precision score of 0.5 after just two hours of initial training, while ResNet-101 and ResNet-152 architectures achieved 27% and 24% accuracy, respectively. These outcomes underscore the potential of ResNet-50 architecture, even with a limited dataset, as a valuable tool for precise crop-type classification within the precision agriculture domain.

RESEARCH OF THE SIDE VENTILATION SYSTEM IN THE POULTRY HOUSE USING CFD

Maintaining a standardized microclimate in the poultry house is one of the main factors. The quality of the output ultimately depends on the quality indicators of the air parameters. Keeping a bird requires great efforts and technological solutions. In connection with this study, there is an improvement of the microclimate system in the air environment of the poultry house due to the inclusion of exhaust fans on the rear end wall in an unconventional way. Computational Fluid Dynamics (CFD) using ANSYS Fluent is a powerful tool for predicting the microclimate system in the poultry house as an alternative to experimental studies. The CFD model was performed on the Navier-Stokes equations for convective flows. The calculations use the Discrete Ordinates radiation model and the Spalart-Allmaras turbulence model.
 The calculations were made with an air consumption of 21.5 kg/s. The temperature of the outside air is assumed equal to +3 ºС and the thermal radiation parameter is entered. For air removal, Munters EM50 1.5 HP exhaust fans are used in a total number of 4 pcs. Inflow valves Wlotpowietrza 3000-VFG with a total number of 80 pcs., which are placed at a height of 0.21 m from the ceiling (1-8 valves) and 0.81 m for 9-40 valves.
 According to the results of CFD modeling of hydrodynamics and heat and mass exchange processes, it was concluded that changing the angle of the spoiler by 73o allows air to be supplied to the center of the poultry house. The upper air layers near the ceiling and near the side wall have a slightly higher temperature. This is accompanied by radiation from the sun and ranges from +21.5 to +24.5 ℃. Since the bird is a source of heat, and in combination with radiation, the air in the room is partially heated. In the center of the room along the entire height, the temperature reaches +15-16 ℃. At the same time, the pressure drop of the inlet valves is 70 Pa, which allows the exhaust fan to be fully supplied. The air velocity at the inlet of the inflow valves is 11.54 m/s. The average air speed at a height of 0.7 m from the floor level is 0.5 m/s, the temperature is 16.55 ℃.
 Thus, the presented scientific research can be used in the future to develop new ventilation systems for poultry houses.

Effect of ventilation strategy on performance of upper-room ultraviolet germicidal irradiation (UVGI) system in a learning environment

Upper-room ultraviolet germicidal irradiation (UVGI) system is recently in the limelight as a potentially effective method to mitigate the risk of airborne virus infection in indoor environments. However, few studies quantitatively evaluated the relationship between ventilation effectiveness and virus disinfection performance of a UVGI system. The objective of this study is to investigate the effects of ventilation strategy on detailed airflow distributions and UVGI disinfection performance in an occupied classroom. Three-dimensional computational fluid dynamics (CFD) simulations were performed for representative cooling, heating, and ventilation scenarios. The results show that when the ventilation rate is 1.1 h−1 (the minimum ventilation rate based on ASHRAE 62.1), enhancing indoor air circulation with the mixing fan notably improves the UVGI disinfection performance, especially for cooling with displacement ventilation and all-air-heating conditions. However, increasing indoor air mixing yields negligible effect on the disinfection performance for forced-convection cooling condition. The results also reveal that regardless of indoor thermal condition, disinfection effectiveness of a UVGI system increases as ventilation effectiveness is close to unity. Moreover, when the room average air speed is >0.1 m/s, upper-room UVGI system could yield about 90% disinfection effect for the aerosol size of 1 μm–10 μm. The findings of this study imply that upper-room UVGI systems in indoor environments (i.e., classrooms, hospitals) should be designed considering ventilation strategy and occupancy conditions, especially for occupied buildings with insufficient air mixing throughout the space.

Energy consumption performance using natural ventilation in dwelling design and CFD simulation in a hot dry climate: A case study in Sudan

Introduction: Sudan is taking proactive steps towards environmental sustainability, including initiatives to improve energy efficiency and reduce costs in a hot, dry climate. This article assesses the contribution of natural ventilation to heat transfer and temperature conditioning in urban areas in Khartoum, Sudan.Methods: The research methodology used a combination of building modeling with computational fluid dynamics (CFD) integrated with IESV Autodesk software to model natural ventilation and simulate energy consumption by incorporating natural ventilation into home design.Results: The best-case scenario for natural ventilation resulted in a 71.1% yearly energy savings. The design point of internal air speed was approximately 0.7 m/s, the point at which 95% of the indoor areas had an average air speed between 0.43 m/s and 0.9 m/s. The worst-case scenario occurred in the east/west direction, when 80% of the interior had an airflow between 0.05 m/s and 0.01 m/s; near open windows, the airflow was approximately 0.1 m/s.Discussion: This study was the first research in Khartoum on the design of clean and energy-saving sustainable architecture. The architectural design process for energy-efficient living in the urban region of Al-Azhari City was implemented and defined in a city quarter in Khartoum. The results showed that natural ventilation can maintain a comfortable indoor temperature in summer and significantly reduce energy costs. The findings may have implications for the design of sustainable buildings in other hot, dry climates.

Occupant's preferred indoor air speed in hot-humid climate and its influence on thermal comfort

As an energy-efficient and high-comfort indoor environment control method, the rational application of airflow in modern buildings has brought renewed attention, especially in hot and humid areas. Chamber experiments were conducted to examine occupants’ preferred air speed and its effects on thermal comfort in hot-humid climate, and the extended thermal comfort zone limit was obtained. Three temperature levels (26 °C, 29 °C, and 32 °C) and two relative humidity levels (40%–60% and 70%–90%) were set, achieving six experimental conditions. During each condition, thirty-six participants were sequentially exposed to two stages with still air and personal controlled stable mechanical airflow produced by electric fans, each lasting 30 min. Their subjective perceptions were collected repeatedly, and skin temperature was measured continuously. For the six conditions, the average preferred air speeds were estimated to be 0.53 m/s, 0.62 m/s, 1.06 m/s, 1.31 m/s, 1.28 m/s, and 1.48 m/s respectively. The preferred air speed at high humidity (70%–90%) was approximately 0.15 m/s-0.3 m/s higher than that at moderate humidity (40%–60%), and such difference increased with air temperature. Elevated air speeds may be used to offset thermal discomfort, as indicated by a 0.2°C–0.5 °C significant decrease in the mean skin temperature and improvements in subjective perceptions. However, for extremely hot and humid conditions including 29 °C/85%, 32 °C/55%, and 32 °C/85%, the discomfort cannot be completely eliminated. When local control of airflow is provided to occupants, the acceptable operative temperature range could be extended by approximately 1 °C regardless of humidity, compared with that under near still air speed below 0.1 m/s.

A Path Stretching Model for Effective Terminal Airspace Management

This study presents a mathematical model to optimize the total fuel consumption per aircraft for the aircraft landing problem (ALP) using the path stretching (PS) method. The PS model applies vector maneuver (VM), speed reduction (SR), and flight path angle (FPA) change methods for aircraft operation. In addition, two different mixed-integer linear programming models utilizing the point merge system (PMS) are presented to compare the PS model as PMS is a widely used method in ALP. The first PMS model uses the VM to handle arrival traffic and solve aircraft conflicts. The second one implements the VM and the SR techniques. Furthermore, an exact solution algorithm is selected to obtain the optimal solution. The PS model aims to increase the number of continuous descent operations by eliminating the level flights. Two different linear regression equations are generated to calculate the fuel consumption and flight time values in descent operations considering realistic aircraft parameters, FPA, and average airspeed. The results demonstrate that the PS model can reduce the total fuel consumption per aircraft by 8.94% and 3.45% compared to the PMS models.

Aeroscapes and the Sensory Ecology of Olfaction in a Tropical Dry Forest

Aeroscapes—dynamic patterns of air speed and direction—form a critical component of landscape ecology by shaping numerous animal behaviors, including movement, foraging, and social and/or reproductive interactions. Aeroecology is particularly critical for sensory ecology: air is the medium through which many sensory signals and cues propagate, inherently linking sensory perception to variables such as air speed and turbulence. Yet, aeroscapes are seldom explicitly considered in studies of sensory ecology and evolution. A key first step towards this goal is to describe the aeroscapes of habitats. Here, we quantify the variation in air movement in two successional stages (early and late) of a tropical dry forest in Costa Rica. We recorded air speeds every 10 seconds at five different heights simultaneously. Average air speeds and turbulence increased with height above the ground, generally peaked midday, and were higher overall at the early successional forest site. These patterns of lower air speed and turbulence at ground level and overnight have important implications for olfactory foraging niches, as chemotaxis is most reliable when air movement is low and steady. We discuss our results in the context of possible selective pressures and observed variation in the foraging ecology, behaviors, and associated morphologies of resident vertebrates, with a focus on mammals. However, these data also have relevance to researchers studying socioecology, invertebrate biology, plant evolution, community ecology and more. Further investigation into how animals use different forest types, canopy heights and partition activities across different times of day will further inform our understanding of how landscape and sensory ecology are interrelated. Finally, we emphasize the timeliness of monitoring aeroecology as global wind patterns shift with climate change and human disturbance alters forest structure, which may have important downstream consequences for biological conservation.

Impacto del diámetro en la distribución de la presión alrededor de una elipse en un arreglo de barras cilíndricas paralelas para diferentes ángulos de inclinación respecto a un flujo de aire en un canal rectangular

The experimental study of the pressure distribution around an obstacle formed by four cylindrical tubes of three different diameters immersed in a transversal flow and at different inclination angles with respect to the flow was carried out. Air at atmospheric pressure was used with a maximum flow of 0.038 Kg / sec. For each cylinder bore and spacing, the pressure distribution is strongly influenced by the angle of inclination, but only marginally affected by flow (within the working range). Due to the turbulent condition of the air flow, with a Reynolds number in the separation between bars from 1695 to 5100, a very good agreement was obtained between the experimental results and a model based on the average air speed in that space, better than a model based on the curvature of streamlines in the gap.

Influence of room layout on airflow distribution in an industrial fruit store

• A wide distance between stack and wall opposite to fans increased flow uniformity. • Fan position above gaps is more efficient for bin ventilation than that above bin rows. • The distance of vertical gaps had little effect on air speed within the bins. • High storage density with 1 vertical gap in every 2nd row does not reduce airflow in bins. Fruit and vegetables are stored for up to several months in large bin stacks in refrigerated rooms. Gaps between the bins and bin wall openings should allow the circulation of cooling air to remove field and respiration heat from produce. In an industrial apple store, the effects of the stacking array, fan position and number on airflow distribution in vertical gaps and inside plastic bins were investigated using stepwise reduction of fan revolution. At 100% fan power, the average air velocity in vertical gaps between bin rows in the main flow direction increased with reducing total cross section of the gaps. In contrast, the number of vertical gaps between bin rows had little effect on the average air speed between fruit inside the bins, probably due to additional flow paths in the horizontal gaps. The lowest air speed was measured when bins were stacked in one block without vertical gaps and a distance to the side walls of only 10 cm. A stacking arrangement with only one central vertical gap between four bin rows or with a large distance (> 1 m) between the wall opposite to the fans and the bins enhanced flow uniformity. Three fans situated above the vertical gaps was more effective for the ventilation of bins than four fans above the bin rows.

Experimental study of the effect of meteorological parameters on the performance of the solar chimney power plant

The solar chimney power plant (SCPP) is an economical technology for the production of solar electricity. The increase in the production efficiency of this type of installation is depended of the several theoretical and experimental studies. This paper studied the effect of some key parameters such as (ambient temperature, solar radiation), on the performance of the solar chimney power plant. Using the dimensions of our SCPP prototype and also compared by the Manzanares prototype with Ouargla weather conditions. Where the maximum solar radiation and ambient temperatures are 957 W/m2 and 30 ° C at 15h00. Respectively. The measured average air speed is 1.04 m/s, and the electric power value of the prototype is 2.04W. The results show that the solar radiation and the ambient temperature have a direct effect in the SCPP efficiency, and also confirm that the technology of solar chimneys is the best solution to install in the hot and arid areas like Ouargla city.

Detailed measured air speed distribution in four commercial buildings with ceiling fans

The layout of ceiling fans in buildings is challenging because of the need to co-ordinate with other elements in the ceiling space, and because the resulting airflows within the occupied space interact with furniture. This study conducted detailed air speed measurements in four buildings with different room sizes, furniture configurations, ceiling fan types, and ceiling-fan-to-floor-area ratios. We measured air speeds across the occupied spaces at four heights while varying ceiling fan operation modes such as fan rotational speed, operating direction, and the number of operating fans. In total, we collected 207,080 air speed samples at 343 sites under 20 test conditions. This paper presents the magnitude and distribution of air speeds, cooling effects, and their influencing factors. The Airspeed Coverage Index (ACI=Fanairspeed(SF)×Fandiameter(D)Averageareaservedperceilingfan(A)) describes the combined effects of multiple influencing factors on the magnitude of air speed. ACI is employed to predict the average air speed and occupant cooling effect, yielding regression confidences higher than 0.95. When designing a space to a target airspeed or cooling effect, the ACI can help to determine parameters such as fan density required for fan choices. The measured data are compared with predictions from the CBE fan tool that had been developed from laboratory tests under simplified conditions. The comparison displays the blocking effects of the furniture, lowering the average air movement in the space, as well as reducing the air movement at the ankle level while increasing it at higher heights. The blocking effect increases with the density of the furniture. We also visually present fan interactions in which triplets of fans are arranged linearly or diagonally, showing that the diagonal layout of ceiling fans increases average air speed and improves its uniformity.

Environmental Conditions and Gas Concentrations in Deep-Pit Finishing Cattle Facilities: A Descriptive Study

HighlightsTemperature and air movement in the naturally ventilated barns correlated to ambient conditions.Manure N-P-K values related to solids distribution in the manure storage.Ammonia and combined sulfur concentrations increased with closer proximity to the manure surface.Influences of manure properties, airflow conditions, barn design, and management were evident for gas concentrations.Abstract. There is a lack of data to describe the range of environmental and air quality conditions in beef cattle confinement buildings with deep-pit manure storage. The objective of this article is to describe the environmental conditions, manure nutrient concentrations, and aerial gas concentrations for three deep-pit manure storage finishing beef cattle facilities and varying weather conditions. Measurements were collected from three barns finishing beef cattle with deep pits in Minnesota on three sampling days per barn in summer, fall, and spring weather conditions. The air temperatures throughout the barns closely mirrored the ambient temperature conditions, although significantly lower temperatures were sometimes evident at the manure surface or in the inlet opening. However, the manure and floor surfaces had 2°C and 5°C temperature increases over ambient temperatures. Air speeds through the barn openings were generally 40% of the ambient wind speed; at animal level, the average air speed was 1 to 3 m s-1. Manure nutrient distributions were not consistent between the surface and agitated (whole pit) samples, and this was likely due in part to solids distribution in the storage. Total nitrogen levels ranged from 4.5 to 6.7 g L-1, and ammonium-N was 50% to 65% of total N in agitated whole-pit samples. Phosphate and potassium oxide levels ranged from 2.8 to 4.2 g L-1 and from 3.7 to 4.5 g L-1, respectively. Aerial ammonia and combined sulfur concentrations varied by location within a barn, pen, and season. Ammonia and combined sulfur increased with proximity to the manure surface. Higher ammonia and combined sulfur concentrations at manure level and floor level for one of the three barns may have related to water quality and/or feed composition and resulting manure nutrients, in addition to warmer temperatures. At floor level, the greatest average ammonia concentration was 8.5 ppm, and 3.9 ppm at nose level. Maximum combined sulfur levels were a maximum of 270 ppb at floor level in summer conditions in one of the barns, while 52 ppb was the maximum average during spring conditions. Carbon dioxide levels also varied by location within a barn, pen, and season and were related in part to the presence of cattle in the pen. This project is the first to quantify air quality in slatted-floor cattle barns and contributes to a body of knowledge that can be used to develop process-based models for estimating air emissions from cattle facilities. Keywords: Airflow, Ammonia, Beef cattle, Confinement, Hydrogenslfide, Manure characteristics, Temperature.

Study of PLTMH development planning in sasnek village sawiat district, South Sorong Regency West Papua Province

Electricity is needed by the whole society. Sasnek village is one of the villages located in Sawiat District, South Sorong Regency, West Papua Province. Sasnek village is very clear and inhabited around 100KK. This village has not been served by electricity until now. Micro-hydro power plants are small-scale power plants whose capacity presents between 100 W to 100 kW. This study will be used for loading stages with a 12 Volt DC power capacity, because it is one of the most efficient, young and safe ways. Measurement of air discharge, discharged by 2 liters / second from a measurement area of 5 m2 and an average air speed of 00.65 m / d. However, due to the condition of the river water flowing throughout the year in the sense of never dried, then used a correction factor of 0.75. Thus the flow that can be used is equal to 0.65 m3 / d. Based on the analysis of the potential contained in Sasnek PLTMH, it can be calculated Distribution Grid sourced from Sasnek PLTMH is 10 KW.With the careful planning so that the results of its implementation will give a positive impact to be meeting the needs of electricity in the village and surrounding villages sasnek.

Accelerometry predicts muscle ultrastructure and flight capabilities in a wild bird.

Muscle ultrastructure is closely linked with athletic performance in humans and lab animals, and presumably plays an important role in the movement ecology of wild animals. Movement is critical for wild animals to forage, escape predators and reproduce. However, little evidence directly links muscle condition to locomotion in the wild. We used GPS-accelerometers to examine flight behaviour and muscle biopsies to assess muscle ultrastructure in breeding black-legged kittiwakes (Rissa tridactyla). Biopsied kittiwakes showed similar reproductive success and subsequent over-winter survival to non-biopsied kittiwakes, suggesting that our study method did not greatly impact foraging ability. Muscle fibre diameter was negatively associated with wing beat frequency, likely because larger muscle fibres facilitate powered flight. The number of nuclei per fibre was positively associated with average air speed, likely because higher power output needed by faster-flying birds required plasticity for muscle fibre recruitment. These results suggest the potential for flight behaviour to predict muscle ultrastructure.

Windbreak Wall-vegetative Strip System to Reduce Air Emissions from Mechanically-Ventilated Livestock Barns – Part 1: CFD Modeling

The adverse effects of air emissions from animal feeding operations (AFOs) on public health, environment, and quality-of-life have been well-documented. Regulations or lawsuits may force AFOs to reduce their air emissions. Since livestock barn particulate matter (PM) has relatively high particle density and diameter and many gasses adsorb onto PM, its filtration might reduce air emissions. A porous windbreak wall that imposes acceptable backpressure (< 12.5 Pa) and covers the fan could be a promising option. Seventy-two different porous windbreak wall scenarios were modeled to compare their backpressure on the fan as well as average airspeed over the ground. These scenarios were combinations of shape (box, chamfered, curved), size (lengths of 2, 2.5, and 3 fan diameters), presence or absence of an opening (opened and closed), screen porosity (mosquito screen or clean screen, SunBlocker 70% or clogged screen), and fan angle and height. Backpressure and airspeed decreased with increasing windbreak wall length. Generally, the box-shaped windbreak wall had lower backpressure and airspeeds than the other shapes. The increased backpressure with clogged screen even at two fan diameters (2d) was acceptable. The tilted fan commonly used in poultry houses had higher backpressure and airspeed over the ground than the non-tilted fan used in swine houses due to the former’s lower surface area and tilt towards the ground. Overall, taking into account cost considerations and footprint size (for retrofittability), despite its higher airspeed over the ground (vs. larger footprints) and modest reduction in airflow rate, the 2d, open box model seems the most promising option.

Dynamics of body kinematics of freely flying houseflies responding to air turbulence

Abstract From the world's tiny flying bugs to gigantic dobsonflies, inflight locomotion of a flying creature requires complex biomechanical strategies to cope with air turbulence. These unpredictable changes in ambient airflow strength and direction may destabilize body posture and orientation. To record this behaviour in further detail, we scientifically examined how houseflies (Musca domestica) respond to air turbulence. We then, three-dimensionally reconstructed body and wings motion of continuously perturbated houseflies using high-speed videography under laboratory condition. The findings confirmed that houseflies, in general, do not initiate flight when average ambient air speed exceeds ~0.63 ms−1 at approximately ~2% of relative turbulent intensity. This finding contrasts with flies which immediately take-off after being released. During mild turbulent conditions, flies performed take-off but with severe and active modulation of body postures. In addition, the body roll angle fluctuates more severely (18.5-fold increase) compared to yaw (7-fold of increment) and pitch (6.4-fold of increment) during turbulence, highlighting that body roll stability is highly sensitive. This research extends our current knowledge on flies' behaviours during turbulence and how insects achieve their superior flight performance.

Ceiling fans: Predicting indoor air speeds based on full scale laboratory measurements

We measured indoor air speeds generated by ceiling fans in 78 full-scale laboratory tests. The factors were the room size, fan diameter, type, speed, direction (up or down), blade height, and mount distance (i.e. blade to ceiling height). We demonstrated the influence of these factors, showing that the most significant are speed, diameter and direction. With other factors fixed, the average room air speed in the occupied zone increases proportionally with fan air speed and diameter. Blowing fans upwards yields lower but far more uniform air speeds than downwards. We show that for the same fan diameter and airflow, fan type has little effect on the air speed distribution in the region outside the fan blades. We developed several new dimensionless representations and demonstrate that they are appropriate for comparisons over a wide range of fan and room characteristics. Dimensionless linear models predict the lowest, average, and highest air speeds in a room with a median (and 90th percentile) absolute error of 0.03 (0.08), 0.05 (0.13), and 0.12 (0.26) m/s respectively over all 56 downwards tests, representing common applications. These models allow designers to quickly and easily estimate the air speeds they can expect for a given fan and room. We include all measured data and analysis code in this paper.

Air flow and chip removal in minimum quantity lubrication drilling

Abstract Chip removal is a significant problem in high throughput minimum quantity lubrication (MQL) drilling, due to increased feed rates and the lack water-based coolant to flush chips. Chip removal difficulties in MQL drilling may drive the use of increased air pressures at a significant cost and energy penalty. This paper summarizes basic studies of air flow and chip removal for MQL drilling, intended to provide a physical basis for process and tooling design with minimal use of high air pressures. Air flow measurements on drill blanks show that the air flow rate depends primarily on the drill coolant hole diameter and input air pressure. Air speed measurements, made using a novel plate impingement test, show that the average air speed increases with increasing coolant hole diameter, but not with increasing pressure. An energy-based analysis of chip removal shows the effects of drill and process design parameters on chip removal. Trends predicted by this analysis are verified through vertical drilling experiments to measure chip removal efficiency. It is shown that the coolant hole diameter has a large influence on air speed and chip removal efficiency, so that drills with the largest practical coolant hole diameter should be tested before increased air pressure is adopted. It is also shown that increasing the spindle speed improves chip evacuation for helical drills. Recommendations for drilling process design and chip removal testing are also discussed.