High-speed Fan Research Articles

Bipolar Ionization Did Not Reduce Airborne Bacteria in a Lecture Hall.

Ionization treatment of indoor air has attracted attention for its potential to inactivate airborne pathogens and reduce disease transmission, yet its real-world effectiveness remains unverified. We evaluated the impact of an in-duct, bipolar ionization system on airborne particles, including culturable bacteria, in a lecture hall. The ionizer was off with variable fan speed for 1 week, on with variable fan speed for a second week, and on with high and constant fan speed for a third week. We measured ion concentrations and aerosol particle concentrations, and we collected bioaerosol samples for analysis of 16S rRNA gene copies representing total bacteria and colony forming units (CFUs) on Tryptic Soy Agar representing culturable bacteria. There were no significant differences in positive, in-room ion concentrations between any weeks; however, negative, in-room ion concentrations were significantly lower when the ionizer was on with constant fan speed. To account for day-to-day variability in total bacteria concentrations, related to occupancy and other factors, we examined the ratio of CFUs to 16S rRNA gene copies (CFU gc-1) and found no significant differences whether the ionizer was on or off. This result indicates that the ionizer was not effective at reducing levels of culturable airborne bacteria in this study.

Increasing the Power Density of High-Speed Fan Drive Motors

Increasing the Power Density of High-Speed Fan Drive Motors

A CFD Methodology for the Modelling of Animal Thermal Welfare in Hybrid Ventilated Livestock Buildings

Computational fluid dynamics (CFD) may aid the design of barn ventilation systems by simulating indoor cattle thermal welfare. In the literature, CFD models of mechanically and naturally ventilated barns are proposed separately. Hybrid ventilation relies on cross effects between air change mechanisms that cannot be studied using existing models. The objective of this study was to develop a CFD methodology for modelling animal thermal comfort in hybrid ventilated barns. To check the capability of CFD as a design evaluation tool, a real case study (with exhaust blowers) and an alternative roof layout (with ridge gaps) were simulated in summer and winter weather. Typical phenomena of natural and mechanical ventilation were considered: buoyancy, solar radiation, and wind together with high-speed fans and exhaust blowers. Cattle thermal load was determined from a daily animal energy balance, and the assessment of thermal welfare was performed using thermohygrometric indexes. Results highlight that the current ventilation layout ensures adequate thermal welfare on average, despite large nonuniformity between stalls. The predicted intensity of heat stress was successfully compared with experimental measurements of heavy breathing duration. Results show strong interactions between natural and mechanical ventilation, underlining the need for an integrated simulation methodology.

Attenuation of Inlet Distortion Effects on Fans Using Asymmetric Inlet Guide Vanes

Abstract This research proposes and preliminarily analyzes a novel concept to passively reduce the negative impact of deep inlet distortion on the fan of an aero-engine. It consists of placing a row of non-axisymmetric inlet guide vanes (IGVs) just upstream of the fan rotor to induce a spatially varying swirl distribution. The swirl distribution is tailored so as to reduce flow incidence in the distorted flow region and increase it in the undistorted flow region to decrease the fluctuation in aerodynamic force on the fan blades under large inlet distortion that can lead to blade failure, as well as attenuate the negative effect of flow non-uniformity on fan/engine aerodynamic performance. A computational study is carried out on a high-speed (transonic) fan rotor (NASA Rotor 67) from a published distortion study using full-annulus unsteady 3D computational fluid dynamics (CFD) simulations. The asymmetric IGV is designed through a process of manual iterations and CFD simulations to take into account the change in flow redistribution with IGV geometry. The asymmetric IGV design, though not optimized, reduces the aerodynamic force variation amplitude by around two-thirds. Moreover, it allows the fan to recover over half of the loss in total pressure rise due to inlet distortion. The asymmetric IGV is also able to reduce the total pressure distortion at the fan rotor exit. Spanwise analysis indicates that the effectiveness of the asymmetric IGV can be improved on all three metrics if better 3D IGV shaping is performed.

Flow control of a vehicle using reverse flow fan

PurposeThis study aims to achieve optimum flow separation control for a road vehicle using a reverse flow fan on rear side.Design/methodology/approachA full-length reverse flow fan array (fan’s air speed is 50% of the car’s speed) is attached throughout the width of the vehicle at rear edge corner.FindingsThe reverse flow fan array positioned at rear edge of car pushes the airflow against the car’s rear window. It creates the recirculation region and alters the pressure distribution. This reduces the lift coefficient by 150%, which becomes the downforce and reduces the drag coefficient by 22%. As the car speed increases, fan speed should also be increased for effective flow control.Research limitations/implicationsThis active flow control method for 3D Ahmed car body has been studied computationally at low speed (40 m/s).Practical implicationsThis design increases the downforce, thus gives better cornering speed and stability, and decreases the drag which improves fuel efficiency. It can be used for effective flow control of cars (hatchback/sedan). The findings can be applied to the bluff bodies, road vehicles, UAV and helicopter fuselage for flow separation control.Originality/valueThe fan array is attached on car’s rear side, which blows air against the car’s rear window. It alters the pressure distribution and aerodynamics forces favorably. But the existing high-speed fan used in a sports cars sucks the air from bottom and pushes it rearward, which increases both the traction force and drag.

Spiral flow instability between a rotor and a stator in high-speed turbomachinery and its relation to fan noise

Hydrodynamic instabilities in the interstage of turbomachinery and their relation to fan broadband noise are investigated over wide operating conditions. By applying compressible linear stability analysis to the velocity profiles of NASA's high-speed fan rig, source diagnostic test (SDT), three distinct unstable regimes are found: the first mode amplifies disturbances over a wide frequency range including the rotor speed. The second mode rotates much slower and develops inside the outer-wall boundary layer. The third mode spins in the opposite direction. An approach equivalent to dynamic mode decomposition (DMD) successfully extracts these modes from a database of improved delayed detached-eddy simulation (IDDES) solving the SDT geometry at approach and cut-back conditions: the extracted DMD modes generally capture the characteristics of eigenfunctions predicted by the linear stability analysis. At the approach condition, the first two unstable modes seem to interact inside the outer-wall boundary layer, while at the cut-back condition, disturbances associated with the first regime migrate away from the wall. Moreover, outer-wall pressure fluctuations of the IDDES database are Fourier decomposed in the interstage: coherent structures extracted using proper orthogonal decomposition are found to be dominated by duct acoustic modes, and they can be mapped not only to interaction tones but also to broadband noise likely associated with the interaction between disturbances in the rotor wakes and quasi-stationary structures near the outer wall. This interaction noise appears to be radiated to both inlet and exhaust with similar azimuthal-mode distributions; however, the importance relative to other noise sources decreases with the engine speed.

Role of PERK-mediated pathway in the effect of mild hypothermia after cerebral ischaemia/reperfusion.

Hypothermia is an effective method of reducing brain injury caused by a variety of neurological insults. It is aimed to elucidate whether a change in the expression of PERK-mediated pathway proteins is an indicator of the neuroprotective effect of mild hypothermia after cerebral ischaemia/reperfusion. One hundred and ninety-two male C57BL/6 mice were randomly divided into three groups: a sham group, a cerebral normothermic ischaemia/reperfusion (I/R) group and a cerebral hypothermic I/R group. A cerebral ischaemia model was established by ligating the bilateral common carotid artery for 15 min. Mice in the hypothermia group stayed in a cage that was set at 33°C, sprayed with a spray of 70% ethanol, and blown with two high-speed fans. The state of neurons was assessed on micropreparations stained with haematoxylin-eosin and TUNEL. The expressions of GRP78, p-perk, p-eif2α, ATF4 and CHOP were measured by western blot analysis 6, 12, 24 and 72 h after reperfusion. The number of surviving cells was significantly higher in the hypothermia group than in the group without hypothermia (p < .05). The GRP78 expression in the hypothermia group was statistically higher (p < .05) than in the ischaemia/reperfusion group. Optical densities of p-perk, p-eif2α and ATF4 in hippocampus CA1 neurons ischaemia were statistically significantly lower in the hypothermia group than in the ischaemia/reperfusion group (p < .05). The CHOP expression in the hypothermia group was statistically lower (p < .05) than in the ischaemia/reperfusion group. Mild hypothermia for 6 h promoted moderate neuroprotection by mediating the expression of GRP78, p-PERK, p-eIF2α, ATF4 and CHOP.

A Stage Flow Parameter Analytical Model for Transonic Counter-Rotating Compressor and Its Application

This paper proposes a stage flow parameter analytical model for rapid evaluation of a counter-rotating compressor’s performance for design optimization and its application in the design of a transonic counter-rotating fan. In the first part, the velocity diagram method, considering the influence of flow-path geometry variation for enhancing the accuracy, is used to correlate the aerodynamic parameter between the inlet guide vane (IGV), the upstream rotor (R1), and the downstream CR rotor (R2). A profile loss correlation based on Lieblein’s diffusion factor and a shock loss model from a high-speed fan database are incorporated for predicting the rotor efficiency. In the second part, to verify its effectiveness, the analytical model is used for aiding in the aerodynamic design of a transonic CR fan for indicating the optimized combination of design parameters for good efficiency and a high pressure ratio. According to the analytical model and the simulation results, the final selected samples have higher efficiency, with a moderate pressure ratio (0.949/2.67, 0.890/2.99, and 0.841/2.99 for R = 0.1, 0.5, and 0.9, respectively). Finally, the aerodynamic characteristics of the designed transonic CR fan at a relative rotating speed of N = 1.05~0.8 are calculated by using the CFD software Numeca. Simulations indicate that the designed transonic CR fan has a pressure ratio of 2.76, with an efficiency of 0.8405 at the design point, and the efficiency is maintained above 0.821 with a stall margin of 13.3% for N=1.0. The maximum pressure ratio of this CR fan reaches 3.08 and 3.36 for N = 1.0 and 1.05, respectively. If used to provide thrust, calculations indicate that the thrust of this transonic CR fan is 71.8, 65.9, and 35.8 kN for N = 1.05, 1.0, and 0.8 at the near-choke point for the sea-level condition.

Features of Noise Emission from High-Capacity Mechanical-Draft Cooling Towers

The article analyzes the features of noise emission from high-capacity mechanical-draft cooling towers. Dry cooling towers equipped high-speed fans of the FANS and AVG types, and wet cooling towers equipped with low-speed fans of the VG-104 type are considered. To analyze the noise impact produced by mechanical-draft cooling towers, a thermal power plant mathematical model was developed in the Acoustics Computerized Workplace computer program, and acoustic calculations were carried out. In performing acoustic calculations, a change in the power plant output from 116 to 464 MW was considered. The sound level (SL) and sound pressure level (SPL) dependences are constructed for different power plant outputs in using various types of mechanical-draft cooling towers, and the noise emission features from the used fans are analyzed. It has been found that in the case of using high-speed fans, the maximum values by which the sound levels exceed their standardized value can make 9–20 dBA depending on the power plant output. In the case of using low-speed fans, no excess of sanitary standards is observed at the design points over the entire power variation range. It has been shown that mechanical-draft cooling towers equipped with high-speed fans are noisier than those equipped with fans driven by low-speed motors (by 21-27 dBA depending on the plant power and type of the high-speed fan used). Matters of tiered noise emission from high-speed fans are considered. Maps with a height of 100 m with noise level isolines have been constructed, and the tiers of the considered cooling towers with the largest contribution of noise to the design points have been determined.

Analysis of bridge type and bridgeless cuk converter fed motor drives for improved power quality

ABSTRACT In the modern power electronic environment, application of low power, small size and high speed drives is achieving more prominence. In domestic appliances such as power tools, high speed fans, high power blowers etc., electric motors with high performance are attaining huge acceptance. The conventional variable speed drives employed diode bridge rectifier (DBR) and DC-to-DC converter-based methodologies, which hampered the supply by introducing current harmonics and conduction losses. This made these topologies unacceptable as per the standards set by the global power electronic authorities. Although there have been large number of developments in motors and control strategies, the risk and complexity of such drives become bottlenecks in implementation. In this paper, the conventional DBR-based DC-to-DC converter-fed drives are compared and analysed with a bridgeless dc-dc converter and a voltage source inverter-fed motor drive. Due to the low power, high-speed application of Brush Less DC (BLDC) motor, the same is selected for the aforesaid drive scheme. It is envisaged to ascertain that the combination of the same will help achieve almost near Unity Power Factor (UPF) and more efficient control compared to the conventional speed control topologies.

Flexible drought deciduousness in a neotropical understory herb.

PremiseAdaptive divergence across environmental gradients is a key driver of speciation. Precipitation seasonality gradients are common in the tropics, yet drought adaptation is nearly unexplored in neotropical understory herbs. Here, we examined two recently diverged neotropical spiral gingers, one adapted to seasonal drought and one reliant on perennial water, to uncover the basis of drought adaptation.MethodsWe combined ecophysiological trait measurements in the field and greenhouse with experimental and observational assessments of real‐time drought response to determine how Costus villosissimus (Costaceae) differs from C. allenii to achieve drought adaptation.ResultsWe found that drought‐adapted C. villosissimus has several characteristics indicating flexible dehydration avoidance via semi‐drought‐deciduousness and a fast economic strategy. Although the two species do not differ in water‐use efficiency, C. villosissimus has a more rapid growth rate, lower leaf mass per area, lower stem density, higher leaf nitrogen, and a strong trend of greater light‐saturated photosynthetic rates. These fast economic strategy traits align with both field‐based observations and experimental dry‐down results. During drought, C. villosissimus displays facultative drought‐deciduousness, losing lower leaves during the dry season and rapidly growing new leaves in the wet season.ConclusionsWe revealed a drought adaptation strategy that has not, to our knowledge, previously been documented in tropical herbs. This divergent drought adaptation evolved recently and is an important component of reproductive isolation between C. villosissimus and C. allenii, indicating that adaptive shifts to survive seasonal drought may be an underappreciated axis of neotropical understory plant diversification.

Numerical study of a liquid-piston compressor system for hydrogen applications

The use of a liquid-piston system for hydrogen compression is investigated in this paper by means of a computational fluid dynamics (CFD) analysis. In the specific context of hydrogen-driven vehicles, high-pressure storage tanks are key to provide substantial range. The present study focuses on the intermediary compression stage of a compression-storage-dispensing (CSD) station, bringing hydrogen gas from 15 bar to 450 bar, i.e., for a pressure ratio of 30. Until now the liquid-piston technology has not been investigated for hydrogen gas compression at very high pressure, which is the purpose of this study. Simulations of the compressible two-phase flow problem are performed with a volume-of-fluid (VOF) framework using a real gas model for the gaseous phase to account for compressibility effects at large pressure ratios. A particular attention is paid to the numerical model formulation and to the treatment of the thermal boundary conditions. Results are reported using both time-resolved instantaneous bulk thermodynamic variables and global integrated quantities. Different compression scenarios are investigated, which highlights the compromise between compression efficiency and power density. To achieve the targeted pressure ratio at a power density of approximately 540 kW/m3, the compression energy cost reaches 1.67 kWh/kg. Finally the paper proposes an innovative solution to minimise cost and achieve quasi-isothermal compression, based on internal forced convection. For a similar power density, a high-speed fan in the top part of the compression chamber (modelled as a volumetric momentum source of 2500 N/m3) increases heat transfer and leads to a 25-% reduction in compression consumption.

ANALISIS PENGARUH PEMBERIAN PENGATUR TEGANGAN BLOWER PADA KOMPOR TERHADAP EFISIENSI PEMBAKARAN

A biomass stove is one of the alternative tools made from bio pellet as a substitute for LPG gas stove (Liquefied Petroleum Gas). Biomass stoves are currently less known by the public due to their traditional use and lack of socialization of biomass fuels. Starting from the problem, biomass stoves currently need further development in order to be used in daily life. Therefore, it is necessary to develop the biomass stove by adding a 12-volt lithium-ion battery as the main power source and a circuit dimmer as a fan speed regulator. The treatment variable in this study is to provide variations in fan speed. Variations used are low, medium, and high fan speeds. The main fuel of the biomass stove is a wood grain bio pellet with the weight of each bio pellet used per treatment as much as 300 grams. The method used in this study used a one-way ANOVA that produced a difference in variation had no real differences and had a noticeable effect on the rate of combustion, the temperature of the fire, and the length of time the water was boiled.

Assessing Mitigation Strategies to Reduce Potential Exposures to Indoor Particle Release Events

Airborne transmission is a major concern for many infectious pathogens, including the novel coronavirus. Ventilation is the principal engineering method used to control airborne health hazards in buildings. Understanding potential air pollution hazards are a particular concern for highly populated indoor environments, such as workplaces and classrooms. This study discusses the results of ventilation testing in a university classroom which contains two fan coil units as the primary HVAC system. A particle nebulizer was used to release aerosol particles into the air, and multiple particulate measuring devices were placed strategically around the room to measure the particle concentration over time. An exponential particle decay rate is determined from the data and converted to a particle concentration half-life, which ranged from over 60 minutes down to under 10 minutes. We then assess how quickly the particles were removed by ventilation systems with varying conditions, including the addition of both high- and low-cost portable mitigation devices into the classroom. Our results indicate that a low-cost unit, made of a simple box fan with a MERV13 filter taped to it, may perform as well at removing particles from a room as a high-cost HEPA filter unit, owing to a tradeoff between filtration efficiency and the number of air changes per hour. As is observed in numerous other studies, the particle concentration half-life in each classroom setup decreases as the mechanical air changes per hour increases from about 1.3 to 9.3. These results are used to evaluate the potential personal exposure risk associated with various classroom ventilation setups. Our results indicate that, when compared to running the fan coil units on low fan speed, operating on a high fan speed reduces potential exposure by 22% and using a portable HEPA filter in the room reduces potential exposure by 66%.

Comparison of Techniques for the Estimation of Flow Parameters of Fan Inflow Turbulence from Noisy Hot-Wire Data

Turbulence parameters, in particular integral length scale (ILS) and turbulence intensity (Tu), are key input parameters for various applications in aerodynamics and aeroacoustics. The estimation of these parameters is typically performed using data obtained via hot-wire measurements. On the one hand, hot-wire measurements are affected by external disturbances resulting in increased measurement noise. On the other hand, commonly applied turbulence parameter estimators lack in robustness. If not addressed correctly, both issues may impede the accuracy of the turbulence parameter estimation. In this article, a procedure consisting of several signal processing steps is presented to filter non-turbulence related disturbances from the unsteady velocity data. The signal processing techniques comprise time- and frequency-domain approaches. For the turbulence parameter estimation, two different models of the turbulence spectra—the von Kármán model and the Bullen model—are fitted to match the spectrum of the measured data. The results of several parameter estimation techniques are compared. Computational Fluid Dynamics (CFD) data are used to validate the estimation techniques and also to assess the influence of the variation in window size on the estimated parameters. Additionally, hot-wire data from a high-speed fan rig are analyzed. ILS and Tu are assessed at several radial positions for two fan speeds. It is found that most techniques yield similar values for ILS and Tu. The comparison of the fitted spectra with the spectra of the measured data shows a good agreement in most cases provided that a sufficiently fine frequency resolution is applied. The ratio of ILS and Tu of the velocity components in longitudinal and transverse direction allows the assessment of flow-isotropy. Results indicate that the turbulence is anisotropic for the investigated flow fields.

ОПТИМИЗАЦИЯ ПАРАМЕТРОВ ВЕНТИЛЯТОРНЫХ УСТАНОВОК АППАРАТОВ ВОЗДУШНОГО ОХЛАЖДЕНИЯ ГАЗА

Purpose of the study. Optimization of the parameters of high speed fan units of air coolers, the combination of which achieves the highest economic efficiency of fan units and, accordingly, the most rational range of specific speed values for the modes of maximum efficiency of fan units in combination with the relative diameter of the sleeve. Development of a mathematical model for determining the local values of the parameters of the efficiency of highspeed fan installations. Sustainable development of territories with active subsoil use is closely related to solving the problems of improving industrial safety and the efficiency of cooling the compressed gas at compressor stations of main gas pipelines, which actualizes the problem of mathematical modeling of energy conversion processes in the impellers of fan units of gas air coolers (AVO) to increase the competitiveness of the oil and gas complex RF in the context of globalization. Research methods. To optimize and determine the limiting combination of calculated parameters, the mathematical method of searching for the area of local maxima of a multiparameter problem in this part was performed in two stages: a mathematical model was built for determining the local values of the parameters that ensure the highest efficiency of fan installations with high speed; the most rational limiting combination of design parameters was determined, at which the highest economic efficiency of fan installations is achieved. Research results. The possibility of increasing the economic efficiency of axial fan units of high speed, made according to aerodynamic schemes with one impeller for gas air cooling devices, has been established. Using the mathematical analysis of the basic laws of axial turbomachines, equations for the efficiency of a fan unit and a fan are obtained, depending on the specific speed. Formulas are obtained for the maximum values of the efficiency of the fan and the fan unit of various specific speed depending on the coefficient of the consumpconsumption speed and on the relative diameter of the impeller sleeve. A method is proposed for constructing aerodynamic schemes of axial fan units for air-cooled gas coolers of the "K" type with maximum maximum values of efficiency for given values of specific speed, relative diameter of the impeller sleeve, aerodynamic quality of the impeller profiles, coefficient of aerodynamic resistance of the flow path of the coefficient of flow velocity. The possibility of creating a fan installation with a speed of ny ≥ 400 with an efficiency of at least ηy=0,86. Application area. Enterprises of the oil and gas complex of the Russian Federation for cooling compressed gas using AVO compressor stations of main gas pipelines.

Increase of energy efficiency ratio of a direct evaporative cooler by dynamic behavior with energy and exergy analysis

The present research is about increasing the energy efficiency ratio (EER) in current direct evaporative coolers (DEC) in Iran. Increasing the cooling load and reducing the electrical energy consumption simultaneously (increasing the energy efficiency ratio (EER)) in DEC are the main goals of manufacturers and consumers of this device. When the circulation water pump runs continuously (static state), the circulation water rate is about 1.89 to 2.90 times of the amounts recommended in the reasonable standards. In order to adjust the circulation water rate to the recommended amount by standards, the present study has utilized repetitive cyclic scheduling programs to reduce the circulation rate to the optimal amount, (by turning the circulation pump on and off by dynamic pattern operation). In other words, the circulation pump stays on only for a certain period of a working cycle, and then the pump stays off for the rest of it. The cooling load and EER were measured based on ASHRAE 133 (2015). The results indicated that the cooling load in the dynamic state increased by 5.03 and 6.18 percent compared to the static state at low and high fan speeds, respectively. Moreover, in comparison with the static state, the amount of electrical energy consumed (kW-hr) in the dynamic state decreased by 8.8 and 4.2 percent at low and high fan speeds, respectively. Finally, the coefficient of performance (COP or EER) of the DEC in the dynamic state is increased by 15.16 and 10.78 in comparison with the static state at low and high fan speeds, respectively.

Influence of ceiling fan induced non-uniform thermal environment on thermal comfort and spatial adaptation in living room seat layout

Ceiling fans are common in Indian residences as airflow is important for thermal comfort. Ceiling fans are generally located in the centre of room for good distribution of airflow though airflow is limited to a small area and air velocity is reduced with increasing distance from the fan. Occupants spatially adapt while deciding seating layout considering various functional factors including thermal comfort. This study evaluates the effect of ceiling fan induced non uniform airflow on thermal comfort conditions in four living room seating layouts. The thermal environment was monitored in a living room and ceiling fan induced airflow was measured to study the distribution of airflow in four selected furniture layouts. The thermal environment in seats varied widely due to non-uniform distribution of airflow in the space. Thermal sensations in 12 seating positions of 4 different layouts were analyzed using Tropical Summer Index (TSI) and Predicted Mean Vote (PMV). Thermal comfort conditions in different seats improved at higher fan speeds in all layouts. TSI and PMV based thermal sensations varied from ‘Too hot’ to ‘Slightly Cool’ between warm summer and cool winter tropical seasons. The number of seats with ‘Too Hot’ thermal sensation were reduced at higher fan speed. Overall, seats farther from the fan experience relatively hotter thermal sensation in summer months and are not affected by fan speeds. The study emphasizes the relevance of moveable furniture and role of spatial adaptive behavior in room layout design, where required airflow for thermal comfort is not available within the space.

Iot Based Home Appliance Control System Using Proteus Simulation Software and Blynk Server

Digital Technology has become an integral part of our lives today. Here IoT comes across as a technology which transforms the way we perceive our surroundings. IoT is considered to be a network of interconnected physical objects/things around us that communicate with each other over the Internet. These days, the need for efficient controlling of appliances to minimize power wastage is important as fossils and non-renewable sources of energy are plummeting. So, a smart home system has been developed to monitor and control home appliances remotely from anywhere. This has been executed on a virtual simulator namely Proteus where the hardware circuitry has been designed. Blynk app has been used to send the user’s command to the circuit through the local cloud server connected with Arduino and Bluetooth module. The basic home appliances like fan, light and room heater which cause unnecessary wastage of power due to turning on of lights during day time or high-speed fans in winter season can be avoided in this way. At the same time the ability to control our everyday appliances over the internet using IoT makes our lives easier, comfortable and tech savvy. Such a system can be used in a wide range of applications such as home automation, smart agriculture, smart industry.

Method of effective circulation control of high speed fans impellors

Research relevance. The high-level competitiveness of Russian oil and gas sector enterprises in the global economic space is impossible to reach without accelerating the restructuring of existing air-cooling apparatuses and developing new ones. It should be carried out with regard to modern technology introduction and advanced achievements in mining. The cost of gas cooling during its transportation via main gas pipelines in the cost structure reaches 22%. Besides, annual energy wastage on compressed gas cooling by fan installations is commensurate with the cost of the air cooling devices. It is essential to develop active means of air conditioning units control in order to improve their efficiency and aerodynamic adaptability that affect the competitiveness of oil and gas enterprises. ISSN 0536-1028 «Известия вузов. Горный журнал», № 4, 2021 99 Research aim is to develop a mathematical model for fan unit parameters active control. Research methods are based on the experimentally proven hypothesis about the dependence between the control flow rate on the impeller blades and the position of the rear critical points of the blades. Research results. A method was developed based on conformal transformations, the theory of residues, singular equations, and hydrodynamic analogy. The dependence between the position of the profiles critical points and flow circulation was obtained. The dependence of the aerodynamic adaptability of the fan units in air conditioning devices on effective critical point position and the energy characteristics of the impeller blades flow controlling source has been established. A patent was obtained for the fan unit impeller with active circulation control from air flow sources from the fan casing. High efficiency of the developed circulation control method for increasing the operational efficiency and aerodynamic adaptability of air-cooled fan units has been proved. An aerodynamic scheme of ОV 121TN was developed. A fan unit OGM VU2.7-1.8K4 with aerodynamic adaptability increased by 34% was created.