Original Fan Research Articles

Optimizing Bionic Blades for Multi-blade Centrifugal Fans: Asymmetric Thickness Inspired by Carangiform Fish

Multi-blade centrifugal fans find wide application across various fields, with their internal airflow exhibiting complex turbulent behavior in three dimensions. Historically, blade optimization relied on constant thickness airfoils, limiting the effectiveness of optimization efforts. However, marine organisms have developed airfoil structures with highly efficient drag reduction, offering a novel approach to optimizing multi-blade centrifugal fans. This study proposes an airfoil optimization design method utilizing variable-thickness airfoils to maintain consistent pressure surface leading-edge parameters. By integrating the Non-dominated Sorting Genetic Algorithm II with biomimetic optimization design, performance improvements are achieved. The study constructs an asymmetric bionic blade using a Bezier curve to fit the mean camber line of the blade. Experimental testing validates the optimized fan's performance, demonstrating the effectiveness of the proposed design approach in reducing the unsteady interaction between the impeller and the volute tongue. This reduction significantly diminishes sound pressure fluctuations on the blade surface. Notably, at the maximum volume flow rate, the optimized fan featuring the asymmetric bionic blade exhibits a remarkable enhancement, with a 10.5% increase in volume flow rate and a notable 1.7 dB reduction in noise compared to the original fan configuration.

Bionic microstructure design of cross flow fan for high aerodynamic and low noise performances

In this paper, a novel approach was introduced for cross flow fan design by incorporating bionic microstructures on the blade surface. Two types of bionic microstructures, riblet and convex hull, were constructed and studied to achieve high aerodynamic efficiency and low noise design. Numerical simulations were conducted to understand the influence of bionic microstructures on the fan’s aerodynamic and acoustic performance, and the impact of design parameters on these performances was investigated. After printing the bionic microstructure fan samples, the experimental tests were carried out. The flow field and sound field data of the fans with bionic microstructures and the original fan were compared. The results demonstrated that both riblet and convex hull microstructures effectively improved the fan’s aerodynamic performance by reducing turbulent kinetic energy on the blade surface. Additionally, the microstructures inhibited boundary layer separation on the suction surface of adjacent blades, which contributed to reducing vortex noise. However, the pressure gradient formed near the convex hull and the edge of the small-diameter riblet resulted in deterioration in the noise of the corresponding fan. By optimizing the diameter and spacing of the riblet microstructure, the best noise reduction performance was achieved for the riblet fan. The optimized fan showed a 5.3% increase in maximum air volume flow rate and a 2.4 dB(A) reduction in noise. Overall, the cross flow fan design method based on bionic microstructures has valuable application potential in improving the aerodynamic and acoustic performance of various rotating machinery.

Effect of impeller structure on aerodynamic performance and noise reduction of a small multi-blade centrifugal fan

In this study, the numerical simulation and orthogonal test are combined to study the effects of blade outlet angle, blade inlet angle, and blade number on the centrifugal fan flow characteristics, stress distribution, and noise control. The experimental tests were carried out to confirm the accuracy of the computational model. The computational fluid dynamics (CFD) technology was used to establish 16 groups of impeller models and derive the optimal parameter combination form. The results show that the blade inlet angle and outlet angle have more significant effects on efficiency and flow rate of fans. Among different optimize structures, the A8 fan with an inlet angle of 60°, an outlet angle of 180°, and a blade number of 45, has the best aerodynamic performance, with a 17.4% increase in flow rate, a 3.3% increase in efficiency, a 7.6% reduction in noise and a 23.0% reduction in impeller stress, compared to the original fan. Reasonable adjustment of the inlet and outlet angles greatly improves fluid distribution and suppresses flow separation. Furthermore, the noise can be reduced by lessening the disturbance between the volute tongue and wake flow, so the flow state gets greatly improved at the volute tongue region.

The Fan Design Optimization for Totally Enclosed Type Induction Motor with Experimentally Verified CFD-Based MOGA Simulations

The energy efficient electric motors save energy thus reduce operating costs. Since there are several losses affecting the motor efficiency, fan design plays an important role to minimize these losses. This study examines the effects of the design parameters of a radial bladed fan on the motor efficiency in a 132 frame with a power of 7.5 kW. The parametric analysis was carried out with the computational fluid dynamics method, and the results were used for the multiobjective genetic algorithm (MOGA) optimization study with the highest efficiency and the lowest motor body temperature objectives. The hub height, hub radius, distance to body cover, blade rising angle, fan cover entrance distance, blade edge angle, blade center radius, blade edge radius, blade end radius, and center edge distance were selected as optimization parameters. 151 simulations were performed. The results showed that the most important parameter for fan efficiency is the hub height which is the parameter that determines the height of the fan impeller diameter. According to the results, the optimum fan design increased the efficiency by 8% compared to the original fan and reduced the winding temperature by 8 °C. The optimized fan design was manufactured and tested against imulation data. This study contributes to sustainable development goals by improving motor efficiency that reduces the cost, designing of new components, and cooling the fan effectively that reduces the amount of copper used.

An innovative noise reduction blower fan housing design used in electronics cooling

Electronic devices are equipped with blower fans as a means of removing the heat that accumulates in them. This type of fan operates smartly by increasing the speed of the impeller as the electronic devices become overloaded. When the speed of the motor increases, it creates unwanted noise that may be harmful to the ears of the user. Therefore, it is imperative to reduce this noise while maintaining the same dimensions of the fans. The purpose of this work is to demonstrate how critical measurements can be used to improve the design of blower fan housings. By making a change in the housing of the fan, this study proposes an innovative solution to the noise problem associated with heat radiation fans. A punch has been added to the new housing of notebook system, which may be located on either the upper or lower sides. A punch should be located at the air inlet on the fan's air outlet side, between 0 and 90°. Moreover, a punch should have a height ranging from 0.3 to 1 ​mm and a circle size ranging from one eighth to one fourth. Additionally, the details of noise measurement are presented. The results of the study showed that the noise reduction was enhanced by more than 2 ​dB(A) which can either result in a performance enhancement by increasing the flow rate to reach the same flow rate as the original fan or in a decrease in human discomfort by lowering the noise level. The work has been patented under patent numbers TWM624190U, and CN216554487U.

Cobra Kai Never Dies! Generational seriality and revived legacies of The Karate Kid

AbstractThis article investigates the hallmarks of generational seriality—the term coined by Matt Hills—using Cobra Kai, and its predecessor, The Karate Kid trilogy, as case studies. It combines textual analysis of overarching themes of these texts, such as the portrayal of white masculinity, and aligned conceptualizations of class, with the examination of televisual nostalgia. It draws on existing scholarship on TV returns and revivals, exploring how Cobra Kai enters a dialogue with the fans of the franchise, and how that dialogue is articulated. While building upon the iconography familiar to The Karate Kid fans, Cobra Kai contains a great degree of self‐reflexivity, with dialogue or entire plot lines that parody regressive gender politics of the 1980s. The series brings together the generic conventions of the teen film and ample opportunities for nostalgia in its original fan base; thus, it significantly expands its appeal to two distinctive demographics.

Investigation on the comparison analysis of the characteristics between the Forward and Backward curved fan system and the Improvement on flow/noise performances by optimizing blade angles in clothes dryers

Recently, the needs for clothes dryers are rapidly increasing due to the consumer's interest in convenience for time reducing and cleanliness like dust. The drying performance of these clothes dryers is greatly affected by the fan system. The fan system affects the flow performance and is related to drying time of clothes dryer. Also, the aerodynamic noise generated by the fan system in the dryer has a great influence on the overall noise of the machine. Because of these reasons, many manufacturers are conducting researches on improving the performance of the fan system in the dryers. The purpose of this study is to improve the flow & noise performance of a fan system in clothes dryer using CFD (Computational Fluid Dynamics) and acoustic analogy based on FW-H (Ffowcs-Williams and Hawkings) equation. The numerical analysis on the flow characteristics of the fan system is conducted by ANSYS FLUENT. The 3-dimesnsional incompressible RANS (Reynolds Averaged Navier-Stokes) equation is adopted as the governing equation and the SST k-ω model is used for turbulent model. The integral surface for FW-H equation to analyze the acoustic field is composed of the closed surfaces including the scroll. This study investigates more suitable fan for a dryer system by comparing the flow characteristics of a backward curved fan, already adopted to a dryer, with a new forward curved fan which has same diameter. To improve the flow performance, the blade angles have been tuned by the design optimization which is the response surface method for geometric parameters. As a result, the dryer with the forward curved fan, which had optimal blade angles, reduced the rotating speed with the same volume flow rate as the original fan. And finally it showed the much reduced noise level compared to the original fan when the dryer ran.

Non-axisymmetric design and flow field analysis of boundary layer ingesting fans

The inlet distortion problem exists in a boundary layer ingesting propulsion system, and the distortion position is almost stable, which seriously affects the fan performance and stability margin (SM). To effectively improve the distortion resistance of the fan, three non-axisymmetric stator (NAS) schemes are designed according to the parameter distribution law of the distorted flow field in front of the stator under the design conditions in this study, which are based on the solidity matching method of the optimization of the stator inlet geometric angle, chord length, and pitch. The impact of the NAS on the fan performance and the distorted flow field parameters under distorted conditions are numerically studied. The results indicate that NAS can effectively enhance the SM of the fan. Among the three NAS designs, the third one demonstrates a remarkable increase of 74.91% in SM compared to the original fan. The NAS design can promote the fluid re-distribution in the distortion zone, make the aerodynamic parameters more uniform, and thus improve the flow state in the distortion zone. Among the three NAS schemes that are adopted in this research, the NAS design based on the pitch optimization method has the best effect. This design can effectively improve the stator flow field structure, thus significantly improving the SM and the aerodynamic performance of the fan under distortion conditions.

Numerical and experimental studies to increase the HVAC fan performance for electrical vehicles – Part 2

A more efficient impeller was developed to replace the HVAC fan from an electrified vehicle in order to lower his energy consumption. This will lead ultimately to an increase of the electrified vehicle range. Three different impellers were designed having the following modifications than the original HVAC fan: a different angle of attack for the blades, changed blade radius, modified blade length, different positioning of the blades, different number of blades. First study consisted in the testing of all three HVAC impellers using the numerical simulation method. In the second part of this study, the most promising new impeller, given the numerical results, was 3D printed and installed in a new casing, specially built for this study. Then the performance of the impeller it was experimentally tested, and the results were compared with the original fan experimental result from a previous study. The main conclusion is that the old impeller is around 240% less efficient than the new impeller and only by changing one simple component in the electrified vehicle design (HVAC fan in this case), the range of the car can grow with approximately 3.84km for each fully charged battery.

Towards a Manumissive Black Fantastic in Fandom, Fantasy, and Literature for Young People, or: A Case for the Black Hermione

This article proposes a method for studying and engaging in a Black melancholic practice of YA SFF (science fiction and fantasy) fandom. In 2015, a minor fan discourse on ‘the Black Hermione’ rose to public prominence when the Black actress Noma Dumezweni was cast to play Hermione Granger in J.K. Rowling’s new <em>Harry Potter</em> stage play. I argue that the ensuing discourse evidences a fannish desire for authorial sanction that is underrecognized in the field of fandom scholarship. Race and melancholy both inflect experiences of fandom, but fandom studies historically lacks frameworks for considering either. Rowling’s public espousal of a trans-exclusive gender politic since 2019 has made it particularly urgent to address the disappointments and unrealized desires that inform fans’ relations with cultural creators. Though obscured in Rowling’s partial embrace of the Black Hermione, I argue that this 2015 episode stands as an important first boundary case between the scope of Rowling’s imagination and fans’ desires to fit within it. Adapting Ebony Elizabeth Thomas’ framework to name a ‘manumissive black fantastic’, I explore a method for observing modes of fan engagement steeped in racial grief and, coextensively, a method for engaging in racial grief through fandom. By way of demonstration, this article concludes with a short work of original fan fiction.

Aerodynamic performance improvement and noise control for the multi-blade centrifugal fan by using bio-inspired blades

Inspired by the swimming characteristics of carps in the C-shaped starting posture, the bionic design of the blade is developed to improve the aerodynamic performance, reduce noise and conserve energy of multi-blade centrifugal fans. By adopting the reverse engineering method, the bionic equal-thickness blades (BETBs) inspired by the C-shaped starting mid-arc of carp are designed and optimized. Based on the comparison between numerical and experimental results of the aerodynamic performance of fan, the optimal bionic equal-thickness blade (O-BETB) is obtained. When the O-BETEs are applied to the original fan, the flow rate is increased by 6.8% and the noise is reduced by 0.5 dB(A). Further, the reconstructed geometric profile of fish body is coupled into the O-BETB to improve the aerodynamic performance of the fan. The results show that the flow rate with the coupled bionic blades (CBB) is increased by 8.3%, while the noise is reduced by 1.1 dB(A), and the power and efficiency are also optimized. The internal flow field, sound field and acoustic characteristics are analyzed to reveal the generation mechanism of aerodynamic noise. The aerodynamic noise of the fan is mainly concentrated in the low and middle frequency range, and its propagation process has obvious dipole characteristics. Meanwhile, because the profile of CBB is more in line with the flow characteristics in the fan, the separation vortex and secondary-flow vortex in the impeller channel and the unsteady interaction between the blade wake-flow and the volute are significantly suppressed, which is also the main reason for the CBB to reduce the noise.

Sedimentary architecture of the undeformed Lower Miocene Görendağı Submarine Fan deposits from Neo-Tethys Ocean (Eastern Anatolia-Turkey): Tectonic control on preservation of fan morphology

Submarine fan deposits which constitute the remnants of Neo-Tethys are widely observed throughout the Bitlis–Zagros Suture Belt. Most of these deposits are located in the Arabian-Eurasian collision zone and have been intensively deformed due to ongoing tectonic activity. In this study, the depositional characteristics and preservation processes of the undeformed, Lower Miocene Görendağı Submarine Fan deposits, associated with this zone, are studied with respect to their sedimentological and structural features. These deposits display feeder or distributary channels, overbank, and lobe sediments and classical Bouma Ta–d divisions. They are subdivided into inner, middle, and outer fan, according to sedimentological and morphological properties. Sand-rich submarine fan deposits have 39 m thickness and approximately 2 km of lateral extension.The submarine fan body is bounded to the north and the south by two reverse faults, namely the Özyurt and Göktepe faults. These faults formed an accommodation space where the fan was deposited and also caused the deepening of the basin. The position and activity of these oppositely inclined reverse faults, which form a triangular zone, are the main reason for preservation of the original fan morphology in the Görendağı Submarine Fan. Our results indicate that the Görendağı Submarine Fan represents one of the last sequences deposited before the closure of the southern branch of the Neo-Tethys Ocean and also the most well-preserved.

Noise reduction of automobile cooling fan based on bio-inspired design

This study aims to minimize the noise generated by automobile cooling fans. Fan blade structures with ridged surfaces based on bio-inspired principles are 3D printed and used to replace the conventional fan blades. The effect of the bio-inspired ridge structures on the noise reduction of the cooling fan is demonstrated by orthogonal experiments in a semi-anechoic chamber. Experimental results show that with an increase in the rotational speed, the effect of the surface textures on the acoustic performance of the cooling fan becomes more significant. For example, at a fan speed of 1750 r/min, all the bio-inspired blade designs reduce noise compared with the original fan and, in particular, the sound pressure level is reduced by 3.83 dB(A) for the design with a ridge width of 4 mm and a ridge pitch of 15 mm. Through variance analysis of the measured noise, the ridge pitch distance has the most significant impact on noise reduction under low speed conditions whilst, under high speed conditions, the ridge width has the most significant influence. In addition to the experimental studies, computational fluid dynamics (CFD) simulations of the cooling fan are carried out to explain the mechanism of noise reduction for the ridged fan blades. When the fan runs, the horseshoe vortexes generated by the ridge structures disturb the flow of the boundary layer, reduce the influence of the fluid flow on the boundary layer, and delay the transition of the fan blade laminar flow to turbulence. It is also seen that there is a reduction of the intensity of the fan blade trailing edge vortices and the scale of the secondary vortices, thereby achieving the overall aim of noise reduction. This research has significance in the noise reduction design of automobile cooling fans.

Multiparameter and Multiobjective Optimization Design Based on Orthogonal Method for Mixed Flow Fan

Optimization design of an impeller is critical for the energy performance of a fan. This paper takes the promotion of fan efficiency and pressure rise as the optimization objectives to carry out multiparameter and multiobjective optimization research. Firstly, an experimental test bench is built to measure the energy performance of the original fan and verify the accuracy of the numerical method. Then, the hub outlet angle of impeller β1, the impeller outlet angle increment Δβ1, the wrap angle φ, the hub outlet angle of diffuser β2, and the diffuser outlet angle increment Δβ2 are set as the optimal parameters to conduct orthogonal optimal design. The results show that the efficiency of the optimal fan increases by 11.71%, and the pressure rise increases by 50.15%. The pressure and velocity distributions in an optimal fan are uniform, the internal flow separation is weakened, and the influence of tip leakage flow is reduced, which makes for the improvement of energy performance for the fan.

Effect of Gurney Flap on Performance and Aeroacoustics of Variable-Pitch Axial Fans

For a variable-pitch axial fan with guide vanes, the effect of three series of Gurney flaps (GFs) configured at the trailing edge of blades on the performance and dynamics is numerically investigated; and the aerodynamic noise is predicted. Simulated results show that GFs increase the total pressure rise of the fan; the higher the GF height, the more notable the lifting capacity. The working point of the highest efficiency moves toward the large flow rate. GF0.5-100 extends the high-efficiency scope and increases efficiency by an average of 2.09%; and GF2-50R raises efficiency by an average of 1.12%. After implementing a GF, the dynamics in the impeller distinctly. Compared with the original fan, a secondary tip leakage vortex generated at the blade tip aggravates the leakage loss; a pair of shedding vortices generated in the downstream of the trailing edge promotes the pressure difference between the suction and pressure surfaces. The prediction with the large-eddy simulation method indicates that GFs heighten the aerodynamic noise of the fan, and GF0.5-100 and GF2-50R increase the sound pressure level by 12 and 13 dB, respectively. Although the GF0.5-100 and GF2-50R are preferred choices for such axial fans, some necessary measures should be taken to reduce the acoustic noise in practical applications.

Effect of blade tip grooving on the performance of an axial fan at different tip clearances in the absence and presence of inlet guide vanes

This research aims at the numerical study of the blade tip grooving effect on the performance of a ducted axial fan at different tip clearances in the absence and presence of inlet guide vanes. To do this, significant parameters of the fan (i.e. pressure and torque coefficients as well as fan efficiency) comprising single- and double-grooved tips are evaluated and compared with those of the original fan. Validation of the considered numerical model is performed through comparison of the numerical findings with experimental results of a single-stage ducted fan, which comprises a set of 37 guide vane and 24-blade rotor rotating at the speed of 3600 r/min. Results reveal that grooving the blade tip causes the fan parameters to increase and higher fan parameters could be attained adopting single-grooved tip. It is shown that employing grooved blades causes the sensitivity of fan parameters to the change in the tip clearance to diminish. Results exhibit that the impact of grooving the blade on the reduction of sensitivity of fan parameters to the change in the tip clearance for the single-grooved tip in the absence of guide vanes is more remarkable than the other cases and in this case, as the tip clearance increases from the lower to the upper considered value, the decreased percentages in pressure coefficient, torque coefficient, and fan efficiency are 29.8%, 8.9%, and 22.8%, respectively. Numerical findings show that the influence of grooving the blade on the fan parameters in the presence of guide vanes is lower than that without guide vanes and in the presence of guide vanes, the highest average increase percentages in pressure coefficient, torque coefficient, and fan efficiency relative to those of the original fan, which is observed in the single grooved tip, are 3.1%, 1.4%, and 1.7%, respectively.

Повышение эффективности промышленных вентиляторов при работе на нерасчетных режимах

This paper’s aim is enhancement of efficiency for fans adjusting by turn of rotor blades. A high load axial fan and a fan with decreased rotor’s pitch chord ratio by reduction of blades number were investigated. Have been performed tests of the fan with design characteristics as follows: theoretical head coefficient Ht = 0,3, mass flow rate Ca = 0,4, hub’s relative diameter ν = 0.6, and with blades, graded on the law of permanent circulation. The area of effective adjustment was estimated by the performance factor value η* ≥ 0,8. When changing the stagger angles in a wide range from 26° to 70°, the area of highly economical work was in variation ranges 0,26–0,78 for the mass flow rate Ca , and 0,24–0,5 for the theoretical head coefficient Ht accordingly. Tests of fans with a reduced blades number in the rotor (12 instead of 16 for the original fan) has showed that under the same stagger angles the fan’s high-efficiency operating mode is approximately in the same range of Ca variation at slightly reduced values of theoretical head coefficient. Maximal performance factor has increased on 2.5%. Decreasing the number of rotary blades, simplifying the turning mechanism and reducing the weight are possible in the design of fans with increased values of aerodynamic load coefficients.

Aerodynamic Optimization of a Centrifugal Fan Using Response Surface Methodology

In this paper, the optimization scheme of a centrifugal fan under the constraints of the total pressure difference, efficiency and shaft power was carried out. The blade inlet angle ß1A and the blade outlet angle ß2A of the centrifugal impeller were optimized using the Response Surface Methodology (RSM). Nine optimization cases were presented. The aerodynamic performance and the flow field of the optimized model were carefully compared with the original model. The results show that the total pressure difference and the total-pressure efficiency increase by 5.7% and 4.2% respectively after the optimization. Compared with the original fan, the flow field inside the impeller of the optimized fan has been improved. The flow separation existing around the blade suction surface outlet is suppressed significantly. For fields in the volute, the optimization scheme has reduced the local vortex intensity and weakened the vortex scale. The flow field stability around the volute tongue is also correspondingly improved.

Optimization Design of Agricultural Fans Based on Skewed-Swept Blade Technology

Abstract.With the rapid development of modern agriculture facilities, agricultural fans have been widely used due to their low pressure and large airflow characteristics. However, existing agricultural fans have large flow losses and low energy efficiencies. To increase the airflow and energy efficiency of these fans, optimization designs based on skewed and swept blades were carried out. First, a “DDZ” agricultural fan (a leaf model agricultural fan commonly used in China) was chosen as the archetype fan. Its performance curves and flow field distribution were obtained by performance testing and numerical simulation. Second, the stack lines of the skewed blade and swept blade were designed based on the original blade, 3 skewed blade parameters (skewed angle a, x direction control parameter kx, and y direction control parameter ky), and 3 swept blade design parameters (swept angle ß, z direction control parameter kz, and r direction control parameter kr). Finally, the optimal skewed blade design parameters (a = 16.8°, kx = 1.65, and ky = 0.5) and optimal swept blade design parameters (ß = 10.6°, kz = -0.33, and kr =0.6) were obtained using numerical simulations and orthogonal testing, which is a response surface method. The numerical simulation results showed that the airflow and energy efficiency ratios of the optimal skewed blade fan were increased by 4.3% and 20.5%, and those of the optimal swept blade fan were increased by 4.5% and 15.4%, respectively, in comparison with those of the original fan. The flow fields showed that the optimal skewed blade mainly reduced the radial flow at the blade root and the leakage flow. The optimal swept blade mainly reduced the leakage flow by changing the distribution of the static pressure on the blade surfaces. Keywords: Agricultural fan, Skewed-Swept blade, Numerical simulation, Optimization.

&lt;em&gt;The Simpsons&lt;/em&gt; Do the Nineties

&lt;em&gt;The Simpsons&lt;/em&gt; Do the Nineties