Performance Of Axial Fan Research Articles

Active Air Injection Control to Enhance Performance of Hollow-bladed Axial Fan: A Numerical Study

Nowadays, axial fans participate in the most important areas of industry and research, including aviation, navy, wind tunnels, cooling towers, and even automobiles. Thus, more emphasis has been placed on improving their aerodynamic performances. It is important to notice that the parameters involved in designing a fan are mainly concerned with aeraulic power, torque and efficiency. This study investigates the utilization of flow control techniques to improve performances of an axial fan equipped with hollow blades, shroud, and hub. These features grant the fan crucial characteristics, namely, its lightweight and facilitate the blowing action by taking advantage on its hollow parts. The fan's performance is evaluated using a steady RANS numerical model with a k-ω SST turbulence closure, which was validated with experimental data. An active control air blowing through a slot was introduced with various positions and dimensions. The results demonstrate a significant improvement in the fan's performance, with an up to 56% increase in aeraulic power gain, accompanied by changes in the overall flow topology, noticed by closely analyzing the flow structure near the tip clearance.

Numerical investigation of aerodynamic performance of an axial fan blade equipped with vortex generators

Delay in the onset of static stall via passive vortex generators (VGs) results in more efficient equipment. Nevertheless, most studies of VGs are conducted on wind turbine blades rather than other turbomachinery devices like axial fan blades. This study is feasibility research to see whether the aerodynamic performance of axial fan blades improves in the presence of VGs. Therefore, the VGs' effect of a static blade with an elliptical profile having a maximum thickness of 8% chord length and without a twist angle is investigated. Fully resolved RANS (Reynolds-averaged Navier–Stokes) simulation with the shear stress transport k–ω turbulence model at Re = 1 × 105 is used to discover the blade flow characteristics with VGs for two types of fan, eight and twelve blades. It is shown that, in both fans, not only can implementing VGs improve the aerodynamic performance of the blade effectively but also the separation phenomenon is delayed. Furthermore, it is concluded that installing VGs performed better in the 8-blade fan, with up to a 3° separation delay, a 9.88% increase in the maximum lift coefficient, and a 48.15% decrease in the maximum drag coefficient with respect to the clean blade. Analyzing the aerodynamic performance of real axial fans considering rotary blades with twist angles equipped with VGs will be feasible in future research.

Experimental and numerical investigation on conjugate performance of fan and heat exchanger of helicopter oil cooling system

• The overall performance of axial fan was studied with two flowrate adjusting modes. • HEs with different fin structures and flow lengths were designed and fabricated. • Coupling performances of fan and different HEs were studied experimentally. • The flow field of oil cooling system at different air flow rate was simulated. • The performance curves obtained by two modes form a hysteresis region. In this article, a combined experimental and numerical study has been performed to investigate the operating performance of axial fan and oil cooling system. A test rig was established, and six types of plate-fin heat exchangers (HEs) with offset strip and rectangular fins and three different flow lengths of 30 mm, 60 mm and 90 mm at side were designed and manufactured. The performance of an axial fan with front guide vane was experimentally studied by two different adjusting modes: gradually increasing and decreasing air flow rate. The conjugate performances of the axial fan and different HEs were discussed in detail. Moreover, a three-dimensional (3D) model was developed to investigate the flow distribution of the system including fan and 30 mm offset strip fins HE at different flow rates. The results show that: (1) the total pressure performance curve of the axial fan under two adjusting modes could form a hysteresis region near the stall boundary. In the hysteresis region, the fan performance curves showed significant difference under both adjusting modes; (2) when the offset strip fins HE with large flow resistance is considered, the system could have two theoretical working points in the hysteresis region. For the case of HE with 90 mm offset strip fins, the flow rates of the system at two theoretical working points were 25.1 m 3 /min and 34.2 m 3 /min, and the heat transfer capacity of the HE were 23.1 kW and 27.5 kW, respectively. In the current experiment, it was found that the system operated at the point with smaller flow rate; (3) when the HE flow resistance exceeded a certain value, the boundary layer separation of the airflow could occur at the rotor blade. The separation had a small effect on the inlet airflow due to its turbulence kinetic energy was low and basically the same at each blade passage. Therefore, the system did not surge or stall at small flow rate.

Effect Stress and Vibration Analysis at NACA Airfoil towards Axial Fan Blade Performance

Axial fans are widely applied in the industrial sector. Axial fans are used for ventilation systems and other cooling systems. The blade design of the axial fan requires an airfoil study. Unfortunately, there are not many articles that discuss in detail about airfoils, especially on noise and vibration that can have an impact on axial fan performance using computational fluid methods or software. This study performs axial fan analysis using computational methods with ANSYS Fluent, Static Structural, Modal and Harmonic Response software to obtain the values of stress, vibration and fluid flow. The experimental design used is using NACA 1412, 4142, and 6412 airfoils on the tip with variations in angles of 60, 74, and 80. While on the hub uses NACA 9312, 9412, and 9512 airfoils with angle variations of 20, 30, and 60 and simulated to find the value of vibration and stress analysis. The 3D axial fan design is imported into the ANSYS Fluent, Static Structural, Modal and Harmonic Response software. The simulation results using Ansys Fluent, shows the pressure contour with a maximum value of 198.424 Pa and Velocity streamline with a maximum value of 28.8669 m/s. the results of the Ansys Static Structural simulation show that the average total deformation is 9.9275e-008 m. The simulation results using Ansys Modal, show that there is a natural frequency of 287.8 Hz and the simulation results of Ansys Harmonic Response obtained an average total deformation of 5.0809e-012 m and the equivalent stress value with a maximum value of σ y, max = 0.20186 Pa.

Effects of some settings of rotational-molding process on the aeromechanical performance of an axial fan.

The study purposes to establish the influence of some settings of the conventional rotational-molding process on the aeromechanical performance of a hollow-blade axial fan. It is recognized that the surface state quality, the material characteristics and the blades design have an effect on the performances of the turbomachines. The use of conventional rotational-molding is an innovative method well suited for achieved hollow-blade fans, reduced cost and relatively easy manufactured. In the present work the material employed represents one grade of linear low-density polyethylene (LLDPE-3200 natural, supplied by “C4-Polymers Company”). The variables of the process studied attend the initial mass of polyethylene powder, the oven temperature and the heating time. For comparisons, a fan of similar geometry machined in an aluminium block serves additionally as a reference. The results show an optimal choice of the settings of the manufacturing process is necessary to achieve the desired aeromechanical performances for this fan.

Analysis of the Axial Fan Performance Mounted on a 4.5kW Aviation Motor

Integrating an axial flow fan with the rotor is a sufficient cooling method for high-speed and high power density motors. Different from the axial fan design work under ideal intake condition, i.e. the intake flow of the fan is axial and uniform, the flow in actual engineering is more complex, which means the flow characteristics of an integrated fan are changed and disturbed. It leads to a performance penalty of the fan, and in some conditions it makes the fan stall, so it is important to get a knowledge of the flow characteristics and the performance of the integrated fan. A certain 4.5kW aviation motor with integrated axial fan is taken as the research object. Firstly, the motor-fan coupling simulation model and ideal axial intake simulation model are established, in which the mass flow rates are same, then calculation is conducted. Secondly, the simulation results are analyzed and compared, focusing on the performance of the axial fan, especially the static pressure rise, and the conclusion is obtained that the static pressure rise in ideal axial intake situation is higher than that in coupling situation. Furthermore, the reasons for the characteristics change are explored, finding that the increase of flow turbulence due to the more complex wind road structure is the main cause for these changes. This paper investigates the flow characteristics and axial fan performance mounted a whole motor, making a contribution to better understand the changes in fan performance under motor-fan coupling situation.

Influence of a micro-perforated duct absorber on sound emission and performance of axial fans

In this article we investigate the influence of varying flow conditions on the acoustic behaviour of a micro-perforated panel absorber (MPA), applied in the vicinity of an axial fan. The predesign of the MPA was conducted by using the Finite Element Method (FE) in combination with porous material modelling approaches. Experimental results of emitted sound spectra and fan characteristic of different fan blade geometries, positioning of the fan to the absorber, as well as changes in turbulent intensity are presented. The studies showed that the investigated MPA duct reduces the overall sound pressure level emitted by the fan by up to 16 dB while maintaining the same efficiency and pressure build-up. From an acoustic and aerodynamic point of view, it was more efficient if the fan operate downstream of the MPA instead of within the MPA. This arrangement increased the efficiency and avoided high-frequency sound generation, which is caused by the flow through the MPA. The results show that the function of the MPA can be used for different fan geometries and that inlet turbulence improves the properties of the absorber.

Prediction of Aerodynamic Performance of Axial Fan with Leading Edge Serration using Computation Fluid Dynamics

Axial fans are found to be one of the major sources of the noise in modern devices such as PCs, HVAC systems, turbo engines and etc. Lot of researches were going on for decades to reduce this unwanted noise. Researchers have found that application of leading-edge serrations will lead to reduction of noise from the bio-inspired study on the wings of barn-owl. This project involves in the study of effect of Aerodynamic performance of axial fan in terms of pressure drop and aerodynamic efficiency using commercial CFD tool ANSYS FLUENT. Analysis have been carried out for a base model without serration and same model with serrations for various flow rates. The results are validated with the experimental results obtained by Krömer et al [1] and found to be in reasonably good agreement.

Numerical investigation of blade tip with different groove effect and its dynamic analysis of axial flow fan

In turbomachinery field, axial flow fan is the most important component of the rotatory system as it increases the pressure rise and improves fan characteristic. The performance of axial fan with different grooved blade tips simulated using commercial solver. This effect of the various grooved blade on total pressure ratio, noise characteristic, stress deformation, analysis of dynamic characteristics as well as flow distribution are investigated.

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.

Road Tunnel Axial Fan Performance In Situ Test: Taking Qinling Zhongnan Mountain Highway Tunnel as an Example

Axial fans play a pivotal role in the road tunnel ventilation system. Qualified performance of the axial fan is important for both safety and air quality maintenance reasons. Axial fans performance in situ test of Qinling Zhongnan Mountain highway tunnel, the second longest road tunnel in the world, is presented in this research. Performance test items and the qualification criterion, as well as a general framework for the road tunnel axial fan assessment, are recommended. Log-Tchebycheff method is suggested to confirm the location for the measuring lines and points. The precision of the log-Tchebycheff method in air flow rate measuring is verified by comparing with the biharmonic spline interpolation fitting result. The research shows that the log-Tchebycheff method has high precision and good efficiency in the air flow rate measurement of the road tunnel air duct. What is more, the biharmonic spline interpolation fitting method can be applied to obtain a more accurate result. The number of interpolation points of the biharmonic spline interpolation fitting method should be bigger than 2000 to provide quality results.

A Numerical Investigation into the Effect of Blade Trailing-Edge Thickness on the Performance of Axial Fans

This paper presents the results of a numerical investigation into the effect of blade trailing-edge thickness and shape on the performance of a rotor ring model of axial fan. The numerical simulations carried out under this investigation provided the performance characteristics of efficiency, working medium power, and total pressure increase in the function of the volumetric flow rate of the rotor ring. The investigated blade trailing-edge thickness values were 1 mm, 2 mm, and 3 mm. The models for the simulation series were developed with rounded and sharp blade trailing edges, for all thickness values thereof. The rounded trailing blade edges were modelled in the form of an arc over which the conditions of tangency with the upper and lower contours of the airfoil were imposed. The blades of the modelled blade fan were designed with the NACA 65-810 airfoil. To verify the applied turbulence model and mesh settings, experimental tests of the model rotor ring were performed on an axial fan test bed. The obtained experimental data was compared with numerical results. The results showed a significant impact of the thickness and shape of the blade trailing edge on the performance characteristics of axial fans.

Axial Fan Performance under the Influence of a Uniform Ambient Flow Field

In their application to air-cooled condensers, axial fans are often subject to the detrimental influence of ambient flow fields at their inlet or outlet. While effects have been investigated mostly under perpendicular cross-flow conditions on fans operating as part of an array in their target design point, this study aims at examining the integral influence of uniform ambient flow fields on a single axial fan over a wide operating range. For this purpose, a wind tunnel fan test rig has been designed and assessed. Multiple angles between uniform ambient flow field and fan axis are examined in their integral influence on the characteristic curve of two distinct industrial axial fans with varying inlet modifications. Increasingly with the fan flow rate, perpendicular inlet cross-flow was found to always have a detrimental influence on fan performance. The straight bladed fan reacted less sensitively than the forward skewed fan, and the adverse cross-flow influence could be reduced with an inlet guard grille and with short conical shroud extensions. Cross-flow at the fan outlet showed potential static fan pressure increases at low flow rates.

Experimental Investigation on Design Enhancement of Axial Fan Using Fixed Guide Vane

Airflow passes through the rotating blade in an axial flow fan will experience a helical flow pattern. This swirling effect leads the system to experience swirl energy losses or pressure drop yet reducing the total efficiency of the fan system. A robust tool to encounter this air spin past the blade is by introducing guide vane to the system. Owing to its importance, a new approach in designing outlet guide vane design for a commercial usage 1250mm diameter axial fan with a 30° pitch angle impeller has been introduced in this paper. A single line metal of proper curvature guide vane design technique has been adopted for this study. By choosing fan total efficiency as a target variable to be improved, the total and static pressure on the design point were set to be constraints. Therefore, the guide vane design was done based on the improvement target on the static pressure in system. The research shows that, with the improvement in static pressure by 29.63% through guide vane installation, the total fan efficiency is increased by 5.12%, thus reduces the fan power by 5.32%. Good agreement were found, that when the fan total efficiency increases, the power consumption of the fan is reduced. Therefore, this new approach of guide vane design can be applied to improve axial fan performance.

Investigation acoustic effect of the convexity-preserving axial flow fan based on Bezier function

The axial flow fan is the major component of air-conditioning outside units, and the noise reduction has always been the main object of the fan researches in the past decades. Many previous researches have concentrated on the noise reduction of the axial flow fan by changing the tip clearance and blade shape of the trailing edge (TE). In this article, a local convexity-preserving structure at leading edge (LE) has been proposed, which is implemented through retrofit design of the original fan blade based on Bezier function method. The effect on the aerodynamic noise of the convexity-preserving of the improved fan B is investigated. To this purpose, the unsteady flow field in the fan is predicted by solving the incompressible Reynolds-averaged Navier–Stokes (RANS) equations with the SST-SAS turbulence model. The result shows that the convexity-preserving structure is beneficial for the noise reduction without decreasing the axial fan performance. Moreover, the noise frequency spectrograms in the far field and sound pressure of 1/3 octave are given by experiment. The noise-reduction effect of improved fan B is verified by comparing the sound pressure lever (SPL) at different frequency bands.

Effect of Different Airfoils on Performance of Axial Fan

Airfoil has great influence on the performance of axial fan. In order to study performance of axial fan. Four kinds of airfoils have been applied to optimize the impeller of axial fan. The 3D internal flows of the axial fan under different operating conditions were simulated based on a steady numerical method in ANSYS CFX 14.5. The results show that the curve of total pressure of the fan with LS airfoil blades is slightly steeper, and that of the fan with CLARK-Y(C=11.7%) (C is the blade thickness ratio) airfoil blades is relatively flat. The total pressure of the axial fan with CLARK-Y(C=11.7%) blades is highest among others. While achieving the highest efficiency in all the operating conditions except the lowest flow rate. Moreover, the blades loading of the CLARK-Y(C=11.7%) airfoil blades fan is entirely more uniform than that in others. The turbulent kinetic energy distribution on the leading edge of blades shows that the axial fan with CLARK-Y(C=11.7%) airfoil blades fan can improve the turbulent kinetic energy effectively.

Influence of Dihedral Stacking on The Performance of An Axial Fan

This paper presents the effect of positive dihedral (lean) on the aerodynamic performance of a low speed axial fan. The blade profiles of the reference (base) fan are stacked on a radial line at the centre of gravity of each profile. The stacking line of the fan with the dihedral, along which the blade profiles are shifted in the direction perpendicular to the chordline, makes an angle of 45 in the radial direction. The performances of the both fans are investigated by means of ANSYS CFX commercial CFD software and are validated by experiments. Both of the computational and the experimental results show that positive dihedral removes the unstable operation region of the fan. Moreover, the total pressure rise and the total-to-total efficiency are increased at low flowrates. The detailed investigation shows that the induced radial velocity in the outward direction may be the reason of the positive effect of the dihedral at low flowrates. As a result, dihedral stacking extends the stable working range of the fan by removing the unstable region.

SOUND SPECTRUM MEASUREMENTS IN DUCTED AXIAL FAN UNDER STABLE CONDITION AT FREQUENCY RANGE 6000 TO 6600 HZ

Performance of axial fan is found to reduce drastically when instability is encountered during its operation. Performance of an axial fan is severely impaired by many factors mostly related to system instabilities due to rotating stall and surge phenomenon experienced during its operation. The present work involves measuring the sound spectrum measurements in ducted axial fan under stable condition at frequency range from 6000 to 6600 Hz. Objective of the experiment is to measure the frequency domain signal and study the sound Characteristics in ducted axial fan by using spectrum analyser. Different types of FFT signals have been measured under stable condition for the frequency range of 6000 Hz to 6600 Hz with respect to rotor speed and different graphs are plotted for ducted axial fan.

Experimental and Numerical Investigation onto 1250mm Axial Fan

Numerical simulation is of interest for most fan designers to optimize the fan designs. Computational fluid dynamic (CFD) has become an essential tool in almost every branch of fluid dynamics and one of the major tools for fan designs. As the fan designers relying on the numerical simulation, the accuracy of tools such as CFD in predicting the performance has become a subject of interest. This paper validates the CFD modeling of an axial fan design against experimental result. The experimental rig and test procedure are developed with reference to “AMCA standard 210”. The analysis is conducted on 1250mm diameter axial fan with two different blade pitch angle 30° and 40°. Prior to encounter the swirling effect and deflection of velocity vector due to rotor blade, a stator blade with the same profile as rotor blade is used as the outlet guide vanes in opposite direction. The computational model is created according to the experimental condition and applied realistic boundary conditions. The model is simulated using commercial CFD package, ANSYS FLUENT. The results obtained are compared against experimental data (AMCA standard 210) over wide range of flow rate. Provided the modeling strategy is chosen appropriately with correct configuration of mesh density and turbulent model then, the results correlates closely with experimental data. This is shown in this investigation. The guide vane incidence angle determination is also done in this paper for 30° and 40° blade pitch angle. The outcome of this paper would provide confidence for designers in numerical simulation for predicting performance of axial fan. In addition, numerical simulation creates a platform for systems to be optimized with a lower cost and high efficiency outcomes.

Rotor-Stator Distance Effect onto Axial Fan Performance Improvement

Past researches have studied the stator blade guide vane angle implementation respective to the rotor blade angle. And outlet guide vane is recommended to encounter the air swirl problem occurs in the axial flow fan compared to inlet guide vane. This paper presents an investigation on the distance between rotor-stator for an outlet guide vane with fixed stator angle. Two specimens were studied: 30° rotor and 34° stator, and 40° rotor and 44° stator. The stator angle was obtained from previous study, which is the optimized angle for the presented stator blade profile. The distance of 50mm and 500mm between rotor and stator is investigated in this study. This would be the constraint length of motor spacing between rotor and stator. This investigation is to explore the possibility of positioning the guide vane after the motor as a separate fixture to reduce manufacturing and assembly cost of guide vane. To investigate the flow structure and to analyze qualitatively commercial CFD package, FLUENT is exploited. The computational model was validated against experimental data. The experimental analysis is done in reference to AMCA 210-07 standard test procedure and the data presented for rotor without stator guide vane model. The performance curve of the axial fan was plotted to compare the effect of the guide vane distance between rotor and stator. The efficiency curve also obtained from measured power input to motor. The results shows the 50mm-distanced stator perform better than the 500mm-distanced stator. This is because the high swirling of flow from the rotor is well-corrected by the 50mm stator compared to the 500mm stator.