Characteristics Of Fan Research Articles

제트팬 노즐 형상 변화에 따른 기류 및 전력 사용량 특성비교

Recently, residents living in high-density residential zones have been ever increasing, with floor area ratios growing higher following the industrial development and the enhancement of our living standards. Consequently, there is an insufficient number parking spaces. In order to solve the lack of parking spaces an increasing number of underground parking lots are being constructed. Nowadays, jet fan ventilation systems utilizing the airflow induced by jet fans are being widely used for the ventilation of large areas such as underground parking lots and tunnels. The purpose of this actual study is to present a jet fan that is designed to reduce electric power consumption and carbon dioxide emissions through the enhancement of its performance. The airflow characteristics of a jet fan that is widely used for the ventilation of underground parking lots and large spaces were realized during the experiments performed in this study. In order to enhance the performance of the existing jet fan, alternative cases were fabricated and their airflow characteristics, etc. were measured. In addition, the power consumption for each case was also measured, thereby predicting the correct amount of carbon dioxide (<TEX>$CO_2$</TEX>) emissions. Case 1 (inside guide type) presented as an alternative for the basic case was found to be the most superior type. It was considered to be more effective when reducing the power consumption and carbon dioxide emissions by approximately 30% in comparison to the basic case. It is thought that a better performance than that of an existing jet fan can be realized by simply replacing its nozzle part with a new one.

벽걸이에어컨의 원심홴에 대한 과도진동 규명 및 저감

In this paper, experiment and dynamics simulations were carried out to identify and reduce the out-of-plane vibration that occurs in a centrifugal fan of an air conditioner installed to a wall. In a wall-installed air conditioner, large space between a case and heat exchanger is often required for the fan to avoid the collision with the case and exchanger. This large space hinders the slim design of the air conditioner even if air conditioner market demands a slim air conditioner. In the present study, in order to determine the cause of the vibration in the centrifugal fan, the out-of-plane vibration and the physical properties were investigated, and the dynamic characteristics of the centrifugal fan were obtained by experiments. Based on these experiments, a dynamic simulation model was established to determine the cause of the out-of-plane vibration of the centrifugal fan. It was found that the main factor of out-of-plane vibration in the centrifugal fan is the axial misalignment between the centrifugal fan and the motor shaft.

Increased Efficiency of Thermal Calculations via the Development of a Full ThermohydraulicRadiator Model

This paper describes the development of a thermohydraulic radiator model. The setup of the hydraulic as well as the thermal model is explained. For the thermal calculations, a method to predict the air velocity as a function of fan characteristics and radiator geometry is established. The coupling of both models is explained as well. A large part of this paper has been dedicated to the validation of the radiator model. This shows the power of the new model and gives new insights into radiator-fan cooling.

Energy dissipation in the blade tip region of an axial fan

A study of velocity and pressure fluctuations in the tip clearance flow of an axial fan is presented in this paper. Two different rotor blade tip designs were investigated: the standard one with straight blade tips and the modified one with swept-back tip winglets. Comparison of integral sound parameters indicates a significant noise level reduction for the modified blade tip design. To study the underlying mechanisms of the energy conversion and noise generation, a novel experimental method based on simultaneous measurements of local flow velocity and pressure has also been developed and is presented here. The method is based on the phase space analysis by the use of attractors, which enable more accurate identification and determination of the local flow structures and turbulent flow properties. Specific gap flow energy derived from the pressure and velocity time series was introduced as an additional attractor parameter to assess the flow energy distribution and dissipation within the phase space, and thus determines characteristic sources of the fan acoustic emission. The attractors reveal a more efficient conversion of the pressure to kinetic flow energy in the case of the modified (tip winglet) fan blade design, and also a reduction in emitted noise levels. The findings of the attractor analysis are in a good agreement with integral fan characteristics (efficiency and noise level), while offering a much more accurate and detailed representation of gap flow phenomena.

Vibration Level Improvement of Id Fan in a Cement Plant Based On CFD Study of Incoming Dust Particles Streamline

This paper presents numerical study of aerosol flow inside of the induce draft (ID) fan inlet duct of a cement plant and the field observation of the proposed guide plate implementation as vibration reducer. Since ID fan sucks the flow from the outlet of cyclone separator, that is normally swirling flow, and the geometry of the duct tends to produce unbalance fine particles distribution over the duct cross section, the vibration of ID fan increases periodically due to unbalance built-up of the fine particles over fan blades surface. Numerical result shows that, at the ID fan inlet, the distribution of fine particles is unbalance. The ratio of particles concentration in the gas entering fan side and motor side of the ID fan is 1.4 to 1 which influences on the unbalance deposition of sticky particles over related blades surface. Using proper guide plate installed in the last duct elbow before entering to the fan, the ratio of unbalance fine particles concentration reduces to 1.05 to 1 and is kept up to the fan free side and motor side inlets. The proposed guide plate has also already installed in a cement plant ID fan duct and vibration characteristic was also observed during 4 months after tie-in period. The plant vibration observation shows that its level is practically unchanged and maintained at low level (around 2 mm/s at fan side and 0.5 mm/s at motor side) which is still lower than maximum limit (11 mm/s). This condition reduces significantly vibration level and eliminates practically plant stop due to over vibration of ID fan along last 4 months operation which was normally suffered every 1.5 months before implementation of this study.

Fan-independent air balancing method based on computation model of air duct system

This paper presents a novel fan-independent air balancing method based on computational model of air duct system. The method involves five procedures: 1) model formulation, 2) data acquisition, 3) parameter identification, 4) balancing calculation and 5) adjusting implementation. The duct network model consists of models of components like fans and conduits and assembles them by the conservation laws. Instead of using parametric model with constant parameters, the fan is re-modeled as a variable pressure source. The supply pressure near the fan outlet is measured in addition to the conventional measurements of pressures and airflows at the terminals. A model identification algorithm is designed to estimate both duct model parameters and fan pressure. The optimal damper positions corresponding to the desired airflow distribution are computed by the obtained model. In this way, damper adjusting strategies are generated by the computing results where a novel indicator is introduced to handle variations of fan pressure. The performance of this method is validated in a simulated duct network system with eight terminals. The results show that modeling fan as variable pressure source can achieve balancing accuracy within 2% error. Comparing to the previous method base on parametric fan model, this method has advantages of better accuracy, stronger robustness and higher efficiency under various conditions of fan characteristics and disturbances.

Effect of attack angle on flow characteristic of centrifugal fan

In this paper, numerical simulation is performed for the performance and internal flow of a centrifugal fan with different operating conditions using steady three-dimensional incompressible Navier-Stokes equations coupled with the RNG k-e turbulent model. The performance curves, the contours of static pressure, total pressure, radial velocity, relative streamlines and turbulence intensity at different attack angles are obtained. The distributions of static pressure and velocity on suction surface and pressure surface in the same impeller channel are compared for various attack angles. The research shows that the efficiency of the centrifugal fan is the highest when the attack angle is 8 degree. The main reason is that the vortex flow in the impeller is reduced, and the jet-wake pattern is weakened at the impeller outlet. The pressure difference between pressure side and suction side is smooth and the amplitude of the total pressure fluctuation is low along the circumferential direction. These phenomena may cause the loss reduced for the attack angle of about 8 degree.

Lattice-Boltzmann Method를 이용한 이중구조팬의 공력소음 해석 및 저감

본 연구에서는 이중구조팬의 소음특성을 알아보고 소음저감 방법으로 알려진 톱니형 뒷전(Serrated Trailing Egde)을 적용하여 이중구조팬의 소음을 저감시켰다. 해석에는 Lattice Boltzmann Method(LBM)를 이용한 비정상 전산해석을 수행하였으며 해석의 타당성을 평가하기 위하여 시험을 실시하였다. 이중구조팬은 일반적인 팬처럼 단일의 Blade Passing Frequency(BPF)를 갖는 것이 아니라 내부팬과 외부팬 각각의 BPF가 서로 다른 음역대에서 나타나는 것을 확인 하였다. 톱니형 뒷전을 내부팬에 적용하여 경계층에서의 구속와류와 뒷전에서의 와류흘림이 억제 또는 분산되고 광역소음뿐만 아니라 팬의 토크도 저감되었다. In this study, aeroacoustic characteristics of combined fan are investigated and noise was reduced by applying Serrated Trailing Edge which is known as the method to reduce fan noises. Unsteady CFD (Computational Fluid Dynamics) analysis was carried out using Lattice Boltzmann Method(LBM) to figure out the combined fan's aeroacoustics and experimental results was used to verify simulation results. Results show that different BPFs are generated at the each inner fan and outer fan on the different frequency while Blade Passing Frequency(BPF) of general fans is constant on the entire frequency range. Boundary vortex and vortex shedding are suppressed or dispersed by applying the Serrated Trailing Edge to the inner fan. Furthermore, broadband noise and fan's torque are reduced.

대규모 와 모사에 의한 3차원 소형축류홴의 운전부하에 따른 난류유동 특성치 고찰

This paper handled an investigation on the turbulent flow characteristics of three-dimensional small-size axial fan(SSAF) according to operating loads. Also, it was carried out by unsteady-state, incompressible and three-dimensional large eddy simulation(LES). The downstream flow type of SSAF is changed from axial flow to radial flow around the beginning of stall region at the aerodynamic performance curve. Axial mean velocity component largely grows around blade tip at the operating point of A to D, but transverse and vertical mean velocity components as well as Reynolds shear stresses highly develop around blade tip at the operating point of E to H. On the other hand, the peak value of turbulent kinetic energy developed around blade tip shows the highest at the operating point of E.

Interactions between alluvial fans and axial rivers in Yukon, Canada and Alaska, USA

Abstract In contrast with the archetypal definition of an alluvial fan, this study shows that fans interacting with axial rivers in Yukon and Alaska commonly exhibit asymmetrical morphology in planform. Hypothesis tests relating to the geomorphological characteristics of these alluvial fans were conducted on a dataset of 63 fluvial-dominated fans. A significant relationship existed between fan asymmetry and the direction of axial river flow, which was attributed to two factors supported by examples: (1) axial rivers have a propensity to trim the toes on the up-valley sides of fans; and (2) axial river channels are deflected across the broad valley floors, which allows the profiles on the down-valley sides of fans to be longer than on the up-valley sides. However, an asymmetrical planform morphology does not lead to a significant bias in the spatial distribution of surface streams towards the up-valley sides of fans, which typically have shorter profiles from apex to boundary. If the asymmetry in fan morphology is preserved in the sedimentary record, then the interpretation of fan deposits that developed in broad valleys and that interacted with axial rivers would be improved by understanding this modern analogue.

Alluvial and fluvial fans on Saturn's moon Titan reveal processes, materials and regional geology

Abstract Fans, landforms that record the storage and transport of sediment from uplands to depositional basins, are found on Saturn's moon Titan, a body of significantly different process rates and material compositions from Earth. Images obtained by the Cassini spacecraft's synthetic aperture radar reveal morphologies, roughness, textural patterns and other properties consistent with fan analogues on Earth also viewed by synthetic aperture radar. The observed fan characteristics on Titan reveal some regions of high relative relief and others with gentle slopes over hundreds of kilometres, exposing topographic variations and influences on fan formation. There is evidence for a range of particle sizes across proximal to distal fan regions, from c. 2 cm or more to fine-grained, which can provide details on sedimentary processes. Some features are best described as alluvial fans, which implies their proximity to high-relief source areas, while others are more likely to be fluvial fans, drawing from larger catchment areas and frequently characterized by more prolonged runoff events. The presence of fans corroborates the vast liquid storage capacity of the atmosphere and the resultant episodic behaviour. Fans join the growing list of landforms on Titan derived from atmospheric and fluvial processes similar to those on Earth, strengthening comparisons between these two planetary bodies.

Optimization of an open-cathode polymer electrolyte fuel cells stack utilizing Taguchi method

The design of open-cathode polymer electrolyte fuel cells (PEFC) stacks with forced-convection requires a careful consideration on the geometrical and operating conditions as well as the operating characteristic of PEFC stacks and fan used. This paper evaluates the effect of key geometrical and operating parameters on the stack characteristic and their interactions to the thermal, water and gas managements as well as stack performance. A validated three dimensional model for open-cathode PEFC stack with fan and immediate ambient were solved to evaluate the effect of studied parameters on the stack performance. In tandem, an L27 orthogonal array (OA) of Taguchi matrix of six factors and three level designs to determine the optimum combination of parameters as well as their interactions for high, medium and low voltage operation. The result indicates that fuel cell length plays important role on determining the fuel cell performance in term of system characteristic, current density and net power. Optimum combination of design and operating parameters were obtained with the objective function of maximizing net power generated by stack by taking into account the parasitic loads.

Experimental determination of tunnel ventilation axial ducted fan performance

To investigate traffic tunnel ventilation flows, a scaled model of a traffic tunnel with longitudinal ventilation system based on ducted fans is used. Flows in tunnels are influenced by tunnel geometry, fan characteristics, ventilation operation scenario, vehicle traffic, atmospheric factors, etc. To analyze flow fields of tunnels in detail, knowledge of tunnel jet-fan properties and turbulent flow characteristics at the fan exit are required, and can be used as input data for CFD boundary conditions of tunnel flow computation. For this purpose experimental measurements were done using the hot wire anemometry technique. The obtained results, trough ensemble-averaged and time averaged profiles of all velocity components, turbulence intensity, turbulent kinetic energy, integral flow length scales, available Reynolds stresses, Turbulent kinetic energy production rates and the fan thrust performance, are presented. These data allow us to analyze in more detail the influence of fan flow on energy and pollutant removal efficiencies of the tunnel ventilation and to evaluate accuracy of CFD studies on fan improvements.

Performance of low-pressure fans operating with hot air

Performance characteristics of fans are generally provided for the normal temperature and pressure conditions (tI = 20?C, pI = 101.325 kPa, ? I = 1.2 kg/m3). Very often, fans operate in different air conditions, occasionally at different air temperatures. In these cases, equations obtained by the law of similarity are usually used for recalculation of the fan operating parameters. Increasing the inlet air temperature causes a decrease in the characteristic of Reynolds number, and may lead to efficiency lowering of the fan. There are also some empirical formulas for recalculation of fan efficiency, when operating at different air temperatures. In this paper, the common way for obtaining fan performance for different operating conditions (air temperature changing) is presented. The results, obtained by recalculation of fan parameters using a law of similarity, are compared to numerical simulation results of the axial-flow fan operating with different air temperatures. These results are compared with results obtained by some recommended empirical formulas, as well. This paperwork is limited to low-pressure and mid-pressure fans, which represents the majority of all fans used in practice, for different purposes.

대단면국내석회석광산용저풍압국부선풍기개발연구

At present, local limestone mines with large opening employ auxiliary fans for workplace ventilation which have been used in coal mines with much smaller airways. Considering the low static pressure loss in the large-opening mines, high pressure auxiliary fans face serious economical limitations mainly due to their excessive capacity. The optimal fan selected for the ventilation in large-opening working places should supply air quantity enough for maintaining safe environment and keep its operating cost as low as possible. This study focuses on the development of a low pressure auxiliary fan designed to have smaller range of the static head but to have more potential for higher ventilation and energy efficiency. The flow characteristics of high and low pressure auxiliary fans were theoretical as well as experimentally investigated to assess the ventilation efficiency in term of environmental and economical aspects. Moreover, the low pressure fan was tested in two limestone mine sites with small and large cross-sectional areas for evaluating its ventilation efficiency. Results from this study can be applied to improve the economy and efficiency of auxiliary fan for ensuring better air quality and work environment management.

Аппроксимация аэродинамических характеристик вентиляторов местного проветривания при многоцелевом моделировании их работы

Аппроксимация аэродинамических характеристик вентиляторов местного проветривания при многоцелевом моделировании их работы

Statistical Characteristics and Frequency Spectrum Analysis of Fan Induced Airflow Compared with Natural Winds

Electric fans used for cooling or local ventilation are common household appliances around the world, especially in developing countries. They offer many advantages such as low cost and energy savings, as well as easy implementation. However, the airflow from fans is often considered to be less comfortable than the sensations produced by natural winds. In order to avoid the draught induced by fans, and to investigate dynamic airflow characteristics of household fans, an anemometer was utilized to measure the corresponding time series of the air velocity. Statistical parameters, wavelet transforms and power spectrum exponents of air velocity signals from different types of fans were analyzed.The results show that the standard deviation of actual, natural wind velocity profiles is slightly greater than that of mechanically produced wind. More importantly, we found that statistical parameters involving mean air velocity, standard deviation, skewness and kurtosis are insufficient to indicate completely, all the characteristics of mechanical wind. Power spectrum density exponent (ß) also shows the frequency characteristics of airflow. Finally, based on the comparison of ß with a variety of fans, it was found that inducing surrounding air can enhance ß, and reduce the draught.

Potential changes in transportation patterns of New York Islanders fans due to stadium relocation

In 2015 the New York Islanders, a professional men’s ice hockey team in the National Hockey League, will relocate to an arena with more transportation options for fans. The team currently plays at Nassau Coliseum in Uniondale, Long Island, NY, with limited public transportation access. They will move 23 miles west to the Barclays Center, an arena in the heart of Brooklyn, NY, with many public transportation options. This study examined fan characteristics which may influence their likelihood of attending Islanders games at the Barclays Center, including familiarity with public transportation, frequency of game attendance, and demographic factors. An online survey of Islanders fans captured fans’ transportation behaviors when traveling to Islanders games at Nassau Coliseum and their projected frequency of attendance after the move, among other variables. Binary and ordered logistic regression models tested the significance of fan characteristics on the likelihood they attended a pre-season Islanders game held at the Barclays Center in September, 2013, and on how frequently respondents reported they will attend future games in Brooklyn. For both models, fans who use regional rail every workday, compared to those who do not, were significantly more likely to have attended the pre-season game and to report they will attend future games. Transit-use variables performed stronger in models than variables representing fans’ work locations. The results exemplify the importance of familiarity with public transportation options when making mode choice decisions, bolstering the importance of transportation demand management strategies when opening new or relocating existing large event venues.

Optimization of Design Parameters for an Open-cathode Polymer Electrolyte Fuel Cells Stack Utilizing Taguchi Method

Abstract The design of open-cathode polymer electrolyte fuel cells (PEFC) stacks with forced-convection requires a careful consideration on the geometrical and operating conditions as well as the characteristic of PEFC stacks and fan used. The operating point should be located at the intersection point between the fan and the stack characteristic curve. This paper evaluates the effect of key parameters and operating conditions on the system characteristic and stack performance of forced convection PEFC by utilizing computational fluid dynamic approach and Taguchi statistical method. A validated three dimensional open-cathode PEFC stack model with fan and immediate ambient were employed together with an L 27 orthogonal array (OA) of Taguchi matrix of six factors and three level designs to determine the optimum combination of parameters as well as their interactions. The result indicates that fuel cell length plays important role on determining the fuel cell performance in term of current density and net power. Optimum combination of design and operating parameters were obtained with the objective function of maximizing net power generated by stack by taking into account the parasitic loads.

Lift and Drag Characteristics of an Air-Cooled Heat Exchanger Axial Flow Fan

Actuator-disk models (ADMs) use blade element theory to numerically simulate the flow field induced by axial fans. These models give a fair approximation at near design flow rates, but are of poor accuracy at low flow rates. Therefore, the lift/drag (LD) characteristics of two-dimensional (2D) sections along the span of an air-cooled heat exchanger (ACHE) axial fan are numerically investigated, with the future prospect of improving ADMs at these flow conditions. It is found that the blade sectional LD characteristics are similar in shape, but offset from the 2D LD characteristics of the reference airfoil (NASA LS 413 profile) at small angles of attack (αatt&lt;5deg). A deviation between these characteristics is observed at higher angles of attack. The blade sectional lift coefficients for αatt&gt;5deg always remain lower compared to the maximum lift coefficient of the reference airfoil. Conversely, the blade sectional drag coefficients are always higher compared to that of the reference airfoil for αatt&gt;5deg.