Characteristics Of Fan Research Articles

Performance Characteristics of Small-Sized Cooling Fan with High Pressure and High Flow Rate

Performance Characteristics of Small-Sized Cooling Fan with High Pressure and High Flow Rate

Heat Transfer and Flow Characteristics of a Centrifugal Fan with Heat Exchanger Function

Heat Transfer and Flow Characteristics of a Centrifugal Fan with Heat Exchanger Function

Research on Cooling Tower Fan Energy Saving Control System Based on PLC and Inverter Technology

In order to improve the effective utilization of the cooling tower fan industrial circulating water system, and to achieve the purpose of energy saving, the paper developed a closed loop cooling tower fan is jointly controlled by the PLC and inverter energy-saving control system. With the theoretical energy-saving fan characteristics analysis, PLC is used as a controller. Combined with inverter technology, remote real-time communication is carried out via RS485 bus with the host computer, and centralized monitoring to operating status of many sets of fans is realized. Production Practice has proved that under the premise of ensuring the water temperature standards, the inverter deceleration of the cooling tower fan makes significant energy savings effect.

Tectonic controls on the morphometry of alluvial fans around Danehkhoshk anticline, Zagros, Iran

Alluvial fans are important landforms where their morphology and morphometry reflect changes in tectonic, climate, base level, and drainage basin characteristics. Along the margins of tectonically active mountain ranges like the Zagros Mountains, alluvial fans are generally assumed to act as useful landforms for identifying the level of tectonic activity. The purpose of this paper is to evaluate the relationship between active tectonics and morphometric characteristics of alluvial fans around Danehkhoshk anticline in the Simply Folded Belt of Zagros. Morphometric characteristics of alluvial fans, such as area (FA), slope (SF) length of base (BF), width/length ratio (W/L), radius (R), sweep angle (SA) and entrenchment (E) as well as valley floor width-to-height ratio (Vf) and strata dips of anticline limbs (DAL), were measured. The study area was sub-divided into eight tectonic zones and then the mean values of the above-mentioned parameters were calculated in each zone. Result reveals that values of SA, BF and E are directly proportional to DAL. The poor relationships between catchment characteristics (slope and area) and fan parameters are probably due to extensive karstic landforms of catchments having complex hydrologic systems and, hence, result in complex catchment/fan relations. The highly entrenched fans with high sweep angles and long bases are characteristic of tectonically active fronts of Danehkhoshk anticline, having V-shaped valleys (higher Vf values), steep triangular facets and more rotated limbs (higher DAL values). Apart from the tectonic control on fan development, the fan head entrenchment and negative accumulation spaces on most alluvial fans can be attributed to decreased sediment load and discharge the drier the present-day climate regime.

LES에 의한 PAC용 시로코홴의 3차원 전산유동해석

The computational flow analysis using LES technique was carried out to investigate the flow characteristics of a sirocco fan under the maximum flowrate condition. The commercial SC/Tetra software was used for this unsteady and three-dimensional numerical analysis. In consequence, because a flow is unstable within the range of about 50% of a housing depth from a bellmouth around the cutoff region, the passing flow through the blade cascade occurred on the X-Y plane is a slow or a reverse with approaching to the housing inlet. Also, the secondary flow shows on the radial plane of a housing, and its vortex center exists within about 33% of a housing depth from a bellmouth except the cutoff region. Moreover, the flow occurring on the exit plane of a sirocco fan shows a complex secondary flow.

The Korean Wave (Hallyu) in East Asia: A Comparison of Chinese, Japanese, and Taiwanese Audiences Who Watch Korean TV Dramas

The major purpose of this study is to find out what factors are responsible for Hallyu, the flow and popularity of Korean popular cultural products in East Asia, and which direction Hallyu is heading for. To do this, recent structural and institutional changes in the region are examined and the 2008 EASS data analyzed. Opening up of the cultural market and development of the mass media industry, especially television, laid the ground for Hallyu in East Asia. The 2008 EASS data reveal that social proximity and two demographic variables are common factors for the rise of Hallyu in East Asia, but globalization and modernity variables had no effect on Hallyu. Females are more attracted to Korean TV dramas than males, but typical Hallyu fans are youngest in China, followed by Taiwan, and Japan the oldest. Besides these characteristics of Hallyu fans, the quality of Korean cultural products is an important factor in their success abroad. Since the second decade of the new millennium, Hallyu evolves into a new, or second, stage in which its contents, strategy, and media change considerably. Hallyu, representing a case of alternative globalization, signals a new phase in the recent history of globalization.

Contouring the nozzles producing a uniform supersonic flow or a thrust maximum in the presence of a curvilinear sonic line

Within the framework of the ideal, i.e., inviscid and non-heat conducting, gas model we consider the problem of designing the supersonic section of a two-dimensional or axisymmetric nozzle realizing a uniform supersonic flow limitingly similar with a sonic flow when the choked flow involves a curvilinear sonic line. Emphasis is placed on nozzles with abruptly or steeply converging subsonic sections and a strongly curved sonic line formed by the C−-characteristics of the expansion fan with the focus at the lower bend point of the vertical section of the subsonic contour. In the two-dimensional case, the least possible greater-than-unity Mach number Mem at the nozzle exit corresponds to the flow in which the first intersection of the C+-characteristics originated at the closing C−-characteristic of the expansion fan falls on the unknown contour of its supersonic part. For a uniform flow with Me 1 ensures a limitingly rapid flow acceleration and forms the initial region of the supersonic generator of a maximum-thrust nozzle. For this reason, in the case of a curvilinear sonic line the supersonic generators of these nozzles have two, rather than one, bends, which, however, is interesting only for the theory. At least, in the calculated examples the thrusts of the nozzles with one and two bends differ only by a hundredth or even thousandth fractions of per cent.

The early-middle Miocene submarine fan system in the Pearl River Mouth Basin, South China Sea

Based on a large amount of seismic, drilling and core data, the characteristics of the early-middle Miocene submarine fans in the Baiyun Sag, northern South China Sea are investigated. By analyzing the sedimentary processes of submarine fans in SQ21 (SQ21 refers to the 3rd-order sequence with its bottom boundary 21 Ma), a sedimentary model of the sand-rich fans is established and the main factors controlling fan deposition are detailed. The results indicate that from early to middle Miocene the Pearl River Mouth Basin developed seven 3rd-order sequences in all, with each lowstand systems tract (LST) of the sequence corresponding to submarine fans. However, only the fans in SQ13.8 and SQ21 are sand-rich fans, the others being mud-rich fans. The cores reveal that the submarine fans in the Pearl River Mouth Basin developed five lithofacies: (1) mud clast-bearing sandstone, interpreted as channel deposits; (2) typical turbidite sandstones, also interpreted as channel deposits; (3) thin-bedded sandstone and mudstone, interpreted as channel-levee complex deposits; (4) massive sandstones, interpreted as lobe deposits; (5) massive mudstone, interpreted as hemipelagic mud. The sand-rich submarine fans in the Pearl River Mouth Basin mainly developed in LST, and in LST reverse faults were active, which led to the formation of accommodation on the shelf. Different from the theory of classic sequence stratigraphy, the accommodation on the shelf captures terrigenous debris transported by the Pearl River, and the uplift at the edge of shelf serves as a “Linear Source” for the deep water area instead of the Pearl River. Therefore, the fans mainly derived from the eroded debris from the uplift. Factors controlling fan deposition include the basin’s tectonic framework, the evolution of the slope break, relative sea-level changes as well as the evolution of the fault system, and the fans are formed under the combination of the above factors.

An Experimental and Numerical Study on Wake Vortex Noise of a Low Speed Propeller Fan

In order to clarify the relationship between the aerodynamic noise and the flow regime around the rotating blade of a propeller fan operated at the maximum efficiency point and the off-design point, the characteristics of fans with different solidity impellers were analyzed experimentally. At the off-design point, the broadband noise of the high solidity fan was much larger than that of the low solidity fan because the relative velocity increased according to the solidity and the noise sources increased because of the number of blades. In the case of the low solidity fan, the broadband noise due to wake vortex shedding was generated at the off-design point in the low flow rate domain and the maximum efficiency point because the relative flow around the blade separated easily.

The Mechanical Impact of Aerodynamic Stall on Tunnel Ventilation Fans

This paper describes work aimed at establishing the ability of a tunnel ventilation fan to operate without risk of mechanical failure in the event of aerodynamic stall. The research establishes the aerodynamic characteristics of a typical tunnel ventilation fan when operated in both stable and stalled aerodynamic conditions, with and without an anti-stall stabilisation ring, with and without a “nonstalling” blade angle and at full, half, and one quarter design speed. It also measures the fan’s peak stress, thus facilitating an analysis of the implications of the experimental results for mechanical design methodology. The paper concludes by presenting three different strategies for tunnel ventilation fan selection in applications where the selected fan will most likely stall. The first strategy selects a fan with a low-blade angle that is nonstalling. The second strategy selects a fan with a high-pressure developing capability. The third strategy selects a fan with a fitted stabilisation ring. Tunnel ventilation system designers each have their favoured fan selection strategy. However, all three strategies can produce system designs within which a tunnel ventilation fan performs reliably in-service. The paper considers the advantages and disadvantages of each selection strategy and considered the strengths and weaknesses of each.

Low-pressure reversible axial fan with straight profile blades and relatively high efficiency

The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.

Unsteady Flow Field and Noise Characteristics of a Small Axial Flow Fan Used in Narrow Space

Unsteady Flow Field and Noise Characteristics of a Small Axial Flow Fan Used in Narrow Space

Low-pressure reversible axial fan designed with different specific work of elementary stages

Low-pressure axial fan impellers designed according to the principle of equal specific work of all elementary stages have blades whose profile near the fan hub is under a significantly larger inclination angle than at the impeller periphery. In order to minimize the spatial curvature of the fan blades and the fan hub length, impeller blades of low-pressure axial fans can be designed with different specific work of elementary stages, so that the specific work of elementary stages is smaller at the hub than at the periphery. This paper presents the operating characteristics of a low-pressure reversible axial fan with straight blade profiles, designed with different specific work of elementary stages. The fan was tested on a standard test rig, with air intake loading on the suction side of the fan.

Low-Loss-Spray-Application - The Scientific Basis

Summary Limited time frames caused by infection threat and weather demand for efficient pesticide application techniques in modern integrated and organic fruit farming. This demand is best complied by low volume spraying, since it minimizes traveling time and number of fillings per spray treatment, but also minimizes the probability of a contamination of the operator with concentrated pesticides. To obtain good spray deposition, low volume spray application demands small droplets which offer numerous benefits, but also carry a high drift potential. This feature threatened the technique, because no method for spray drift reduction has been available in order to make use of reduced buffer zones to water courses and non-target areas. A new method based on cross flow characteristics of the sprayer fan, canopy adapted forward speed and fan speed and a mixed set of hollow cone nozzles and air induction nozzles resulted in an approx. 85% reduction of particle drift deposits, so that the method has been registered in the official German list of drift reducing devices in the 75% drift reduction class. Besides drift reduction a canopy adapted fan speed also results in an enormous reduction of fuel consumption and noise emission as further environmental benefits of small droplets. An assessment of the influence of a canopy adapted forward speed and fan speed on spray deposit, relative spray cover age and droplet deposit density revealed a significant increase of the application efficiency, rising with decreasing canopy width and compensating a reduction of water volume and dose rate from canopy related dosing models. Testing a tower sprayer in orchards for use with reduced fan speed unexpectedly showed an unusable vertical air distribution. Alarmed by this finding, a subsequent testing of various fan types on a test bench disclosed a very unsatisfying vertical air distribution of many fan types and even within a production series the air distribution differed enormously. Especially an uneven horizontal reach of the air stream over working height is a major obstacle for a successful use of canopy adapted fan speed with all its benefits. Since a uniform vertical air distribution is the basic re quirement for a highly efficient and environmentally safer spray application not only in terms of the potential to reduce pesticide consumption, but also for reducing fuel consumption and noise emissions, testing and adjusting fans of orchard sprayers on a test bench is urgently needed. Because of the importance of the topic, three fruit growers associations in Austria, Italy and Germany together initiated the development of a new test bench to measure vertical air distribution of orchard sprayers.

Analysis on Characteristics of Heavy Vehicle Electrical Cooling Fan with CFD and Motor Test Results

Heavy vehicle cooling fan is seen as one of the main means of vehicular fuel efficiency reduction. This is becoming a major factor in city noise, and the necessity of electromagnetic technical development is very great. CFD method could replace experiment for development of heavy vehicle cooling fan, but it cannot be applicable to some of real design stage because of limitation that rotating speed must be set as boundary condition. In this article, we developed a new algorithm in which we are able to determine both static pressure and rotating speed through setting up the only voltage as a boundary condition with motor performance test results

The Optimal Operation of Thermal Power Plant Auxiliaries Based on Mixed Integer Programming

Optimizing the operation of thermal power plant auxiliaries can effectively reduce the power consumption rate and improve production efficiency. This paper establishes the optimal operation model for variable-speed pumps and fans, which are the main auxiliaries in thermal power plant. The model is based on the operating characteristics of pumps and fans and considers parallel and series operation. The object is to minimize the power of auxiliaries; the constraints contain the requirements of system flow or head, speed limits, flow limits, power limits and pipeline performance. Because of the complexity of the model, the pumps and fans operating performance curves are transferred to piece-wise linear curves at first, then a new 0-1 variable is introduces to characterize the choice of a different Q-P curve at a different speed. The model has been converted to mixed integer linear programming problem and uses commercial modeling tools to solve. The case is to verify the effectiveness of this method.

Numerical Simulation and Experiment Research on Aerodynamic Characteristics of a Multi-Blade Centrifugal Fan

The full flow field model of a widely used multi-blade centrifugal fan was built, and unstructured grids were used to discrete the computational domain. The moving reference frame is adopted to transfer data between the interfaces of the rotating field and the stationary field. Pressure boundary conditions are specified to the inlet and the outlet. The SIMPLE algorithm in conjunction with the RNG k-ε turbulent model was used to solve the three-dimensional Navier-Stokes equations. The steady and unsteady numerical simulations of the inner flow in the fan at different working conditions were presented using the CFD method. The numerical simulation results were validated by contrasting to the experiment results. The results displayed the characteristics of the velocity field, pressure field, pressure fluctuation at two monitoring points in the centrifugal fan. The results can provide basis for optimizing the fan design and the internal flow, and have important value of engineering applications in the increase of the overall performance in operation.

Internal Flow Characteristics of a Variable Pitch Axial Fan Under Abnormal Installation Angles of a Single Blade

Internal Flow Characteristics of a Variable Pitch Axial Fan Under Abnormal Installation Angles of a Single Blade

Similarity Theory Design of Centrifugal Fan’s Impeller

At present a set of wholly mature design methods of impeller theory based on existential experiences do not exist, because of the complexity of internal flow characteristics of centrifugal fan. Therfore it will undoubtedly provide helps for the improving of existing mehtods to fully master the existed successful experience. Based on statistical datas, some new methods used to determine the main geometric parameters of centrifugal fan’s impeller was proposed in this paper.The paper analyzes the internal relations between a large number of existing aerodynamic sketches and performance parameters of centrifugal fans by means of statistical method and finds regularity, so provides help for simplifing calculation procedures and improving the reliability of impeller design.

Prediction of aerodynamic noise in a ring fan based on wake characteristics

A ring fan is a propeller fan that applies an axial-flow impeller with a ring-shaped shroud on the blade tip side. In this study, the entire flow field of the ring fan is simulated using computational fluid dynamics (CFD); the accuracy of the CFD is verified through a comparison with the aerodynamic characteristics of a propeller fan of current model. Moreover, the aerodynamic noise generated by the fan is predicted on the basis of the wake characteristics. The aerodynamic characteristic of the ring fan based on CFD can represent qualitatively the variation in the measured value. The main flow domain of the ring fan is formed at the tip side of the blade because blade tip vortex is not formed at that location. Therefore, the relative velocity of the ring fan is increased by the circumferential velocity. The sound pressure levels of the ring fan within the frequency band of less than 200 Hz are larger than that of the propeller fan. In the analysis of the wake characteristics, it revealed that Karman vortex shedding occurred in the main flow domain in the frequency domain lower than 200 Hz; the aerodynamic noise of the ring fan in the vortex shedding frequency enlarges due to increase in the relative velocity and the velocity fluctuation.