An Investigation Into Performance Characteristics of an Axial Flow Fan Using CFD for Electronic Devices

2015 ◽  
Author(s):  
Hafiz M. Hashim ◽  
Baris Dogruoz ◽  
Mehmet Arik ◽  
Murat Parlak
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Volumetric Flow Rate ◽  
Critical Issue ◽  
Data Sets ◽  
Axial Fan ◽  
Flow Rates ◽  
Cad Models ◽  
And Control ◽  
Control Association

Rotating fans are widely utilized in thermal management applications and their accurate characterization has recently become even a more critical issue for thermofluids engineers. The present study investigates the characterization of an axial fan computationally and experimentally. Using the three-dimensional CAD models of the fan, a series of computational fluid dynamics (CFD) simulations were performed to determine the flow and pressure fields produced by the axial mover over a range of flow rates. In order to validate the computational model findings, experiments were conducted to obtain the pressure drop values at different flow rates in an AMCA (Air Movement and Control Association) standard 210-99, 1999 wind tunnel. These data sets were also compared with the fan vendor’s published testing data. A reasonably good agreement was obtained among the data from these three separate sources. Furthermore, an attempt was made to understand the overall fan efficiency as a function of the volumetric flow rate. It was determined that the maximum overall fan efficiency was less than 27% correlating well with the computational results.

A Comparison of Actuator Disc Models for Axial Flow Fans in Large Air-Cooled Heat Exchangers

2016 ◽  
Author(s):  
Michael B. Wilkinson ◽  
Francois G. Louw ◽  
Sybrand J. van der Spuy ◽  
Theodor W. von Backström
Keyword(s):  
Heat Exchangers ◽  
Three Dimensional ◽  
Axial Flow ◽  
Velocity Profiles ◽  
Low Flow ◽  
Disk Model ◽  
Flow Rates ◽  
Fan Performance ◽  
Actuator Disk ◽  
Performance Results

The performance of large mechanical draft air-cooled heat exchangers is directly related to fan performance which is influenced by atmospheric wind conditions, as well as the plant layout. It is often necessary to numerically model the entire system, including fans, under a variety of operating conditions. Full three-dimensional, numerical models of axial flow fans are computationally expensive to solve. Simplified models that accurately predict fan performance at a lesser expense are therefore required. One such simplified model is the actuator disk model (ADM). This model approximates the fan as a disk where the forces generated by the blades are calculated and translated into momentum sources. This model has been proven to give good results near and above the design flow rate of a fan, but not at low flow rates. In order to address this problem two modifications were proposed, namely the extended actuator disk model (EADM) and the reverse engineered empirical actuator disk model (REEADM). The three models are presented and evaluated in this paper using ANSYS FLUENT. The models are simulated at different flow rates representing an axial flow fan test facility. The resulting performance results and velocity fields are compared to each other and to previously simulated three dimensional numerical results, indicating the accuracy of each method. The results show that the REEADM gives the best correlation with experimental performance results at design conditions (ϕ = 0.168) while the EADM gives the best correlation at low flow rates. A comparison of the velocity profiles shows that none of the three models predict the radial velocity distribution at low flow rates correctly, however the correlation improves at flow rates above ϕ = 0.105. In general the upstream velocity profiles, where reversed flow occurs through the fan, are poorly predicted at low flow rates. At the flow rates above ϕ = 0.137 the correlation between the velocity profiles for the simplified modes and the three dimensional results is good.

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

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Francois G. Louw ◽  
Theodore W. von Backström ◽  
Sybrand J. van der Spuy
Keyword(s):  
Heat Exchanger ◽  
Lift Coefficient ◽  
Axial Flow ◽  
Design Flow ◽  
Low Flow ◽  
Axial Fan ◽  
Flow Rates ◽  
Blade Element Theory ◽  
Lift And Drag ◽  
Air Cooled Heat Exchanger

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<5deg). A deviation between these characteristics is observed at higher angles of attack. The blade sectional lift coefficients for αatt>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>5deg.

Forward Blade Sweep Applied to Low-Speed Axial Fan Rotors of Controlled Vortex Design: An Overview

2012 ◽  
Author(s):  
János Vad
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Suction Side ◽  
Loss Reduction ◽  
Axial Fan ◽  
Flow Paths ◽  
Free Vortex ◽  
Low Speed ◽  
Cvd Method ◽  
Circulation Distribution

An overview is given on the research maintained by the author about design aspects of three-dimensional blade passage flow in low-speed axial flow industrial fan rotors, affected by spanwise changing design blade circulation due to controlled vortex design (CVD), blade forward sweep (FSW), and their combination. It was pointed out that, comparing the CVD method to free vortex design, the fluid in the blade suction side boundary layer has increased inclination to migrate radially outward, increasing near-tip blockage and loss. It was concluded that the benefit of FSW, in terms of moderating loss near the tip, can be better utilized for rotors of CVD, in comparison to free vortex design. Compared to free vortex design, FSW applied to blades of CVD was found especially beneficial in loss reduction also away from the endwalls, via shortening the flow paths on the suction side — being anyway elongated by the radially outward flow due to CVD —, and thus, reducing the effect of wall skin friction. The necessity of correcting the swept blades was pointed out for matching with the prescribed CVD circulation distribution.

Design, Construction, and Control of Curves and Surfaces via Deployable Mechanisms

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Vishal Ramadoss ◽  
Dimiter Zlatanov ◽  
Xilun Ding ◽  
Matteo Zoppi ◽  
Shengnan Lyu
Keyword(s):  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Approximation Technique ◽  
Polygonal Approximation ◽  
Curves And Surfaces ◽  
Cad Models ◽  
Sextic Curve ◽  
Aided Design ◽  
And Control

Abstract There has been an increasing interest in design and construction of deployable mechanisms (DMs) with multiple degrees of freedom (DOFs). This paper summarizes a family of deployable mechanisms that approximates a series of curves and surfaces using the polygonal approximation technique. These mechanisms are obtained by linking the two- and three-dimensional deployable units, which are constitutive of Sarrus and scissor linkages. Multiple unit mechanisms with varying sizes are assembled and alter their shape within a different family of parameterized curves and surfaces. A systematic methodology for polygonal approximation method is presented. Quadratic, semi-cubic, cubic, quartic and sextic curve boundaries, and quadric surfaces are approximated and controlled. Computer-aided design (CAD) models and kinematic simulations elucidate the mechanism’s ability to approximate a set of curves and surfaces.

scholarly journals Flow Analysis in a Spiral Inducer Impeller

1993 ◽  
Author(s):  
J. H. G. Howard ◽  
B. R. Hutchinson ◽  
R. B. Broberg
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Axial Flow ◽  
Tip Clearance ◽  
Flow Rates ◽  
Flow Swirl ◽  
Upstream Flow ◽  
Secondary Flow Field

The flow within an axial-flow spiral inducer impeller is complex and three-dimensional. The long but tightly-spiralled passages give rise to secondary flow fields strongly influenced by the blade walls. Flow analysis in such an impeller is carried out by a three-dimensional viscous flow code and compared with previously published LDV measurements. Due to the extreme blade angles of the inducer, an unconventional meshing strategy is required in order to prevent high mesh non-orthogonality. Details of that strategy are provided. Tip clearance modelling was not incorporated in this first stage of investigation. Despite this, the flow analysis reveals the pattern of development of the secondary flow field along the length of the high solidity passage consistent with the LDV data but in much greater detail than was possible with the limited capability of the measurement system. Predicted flow patterns upstream suggest preconditions for the initiation of the observed induction of upstream flow swirl at reduced flow rates.

Ergonomics in Alternative Vehicle Design: Educating Students on the Practical Application of Anthropometric Data

2019 ◽  
Vol 27 (3) ◽  
pp. 24-29
Author(s):  
John Wanberg ◽  
Michael Caston ◽  
Derek Berthold
Keyword(s):  
Three Dimensional ◽  
Human Interaction ◽  
Vehicle Design ◽  
Data Sets ◽  
Anthropometric Data ◽  
Vehicle Interior ◽  
Industry Standard ◽  
Control Interface ◽  
And Control

An instructor taught students to use industry-standard anthropometric data sets by applying them to a long-term, alternative vehicle design project within industrial design courses. Students learned how to verify existing anthropometric data through physical testing using three-dimensional mock-ups to produce a robust, anthropometrically appropriate model that balances multiple design constraints. As a practical exercise, students examined aesthetics and control interface of the vehicle interior focusing on human interaction, optimum comfort, and control within the confined constraints of the aerodynamically optimized vehicle packaging. Ultimately, students gained insights into how to apply ergonomics to new, varied design challenges through these educational tasks.

Application of Deterministic Correlations in the Analysis of Rotor-Stator Interactions in Axial Flow Fans

2012 ◽  
Author(s):  
Mónica Galdo Vega ◽  
María Rodriguez Lastra ◽  
Katia María Argüelles Diaz ◽  
Jesús Manuel Fernández Oro
Keyword(s):  
Reference Frames ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Flow ◽  
Deep Understanding ◽  
Single Stage ◽  
Design Flow ◽  
Flow Conditions ◽  
Axial Fan ◽  
Deterministic Models

Deterministic stresses account for the time-averaged contribution of the periodic unsteadiness in single-stage turbomachinery. An accurate modelling of these stresses allows for the development of steady simulations with full contribution of deterministic unsteady sources. Moreover, introducing both relative and absolute reference frames, the deterministic tensor can be split into a set of correlations which addresses the influence of the stator and rotor non-uniformities separately. As a consequence, a pure unsteady term showing rotor-stator interaction is rediscovered and can be established as an essential indicator of the strength of viscous, non-linear effects in multistage turbomachinery environments. This work provides a comprehensive description of these correlations in the interrow region of a single stage axial flow fan. Two configurations are analyzed here: the upstream stator acting as a non-uniform inflow for the rotor and the complementary stator placed downstream of the rotor for pressure recovery at the exit. To illustrate the driven mechanisms in the tensor, a three-dimensional numerical simulation at the midspan section of a low-speed axial fan is employed in the present investigation. A deep analysis of the interaction between the rows using the deterministic framework is shown as a useful tool to devise deterministic models for steady computations. The commercial code FLUENT is used to resolve the full unsteady 3-D Navier-Stokes equations using LES schemes. Nominal and off-design flow conditions have been considered to observe the relevance of the different deterministic correlations in the establishment of the unsteady sources. The final objective pursues a deep understanding of the correlations behavior under variable flow conditions and different stage configurations. Thus, physical insight will be gained and more efficient and reliable deterministic models could be proposed, available for researchers and experts in the field.

A Study on Surge and Stall under the Interaction of Parallel Axial flow fan in Tunnel

2011 ◽  
Vol 42 (11) ◽  
pp. 9-14 ◽  
Author(s):  
Guo Chun ◽  
Wang Mingnian ◽  
Tang Zhaozhi
Keyword(s):  
Mutual Influence ◽  
Frequency Control ◽  
Axial Flow ◽  
Periodic Oscillation ◽  
Axial Fan ◽  
Axial Flow Fan ◽  
Stress Effects ◽  
Fan Selection ◽  
Power Needs ◽  
And Control

In the ventilation design for tunnels above 10km, an axial flow fan of great power needs to be set in ventilation shafts. There are few provisions on the setting modes and less discussion of parallel axial flow fan mode in the Specifications for Design of Ventilation and Lighting of Highway Tunnels. All of these bring a lot of difficulties about the axial fan selection, layout and control design. There is no specialized research on axial flow fan for tunnels and no studies on surge and stall under the interaction of parallel axial flow fan in tunnel in spite of the more and more application of parallel axial flow fan. So, this paper conducts a study on surge and stall under the interaction of parallel axial flow fan in tunnels. Through the study on the operating principle and analysis of parallel axial flow fan, we can know that the noise will increase suddenly, which will in turn result in fan vibration and running instability once the stall occurs. When a fan surges, the air volume and pressure, the motor current will fluctuate sharply, which brings significantly increased vibration and noise. At the same time, the rotary blade and the shell are subject to considerable stress effects and the fan will possibly suffer from great damage. The surge will occur in the unstable zone of axial fan performance curve. The strong pulsation and periodic oscillation of the air flow will increase the noise, which is a serious damage to the fan. So an axial fan should avoid this zone in running. With two axial flow fans of the same power parallel, the mutual influence is not very great. Therefore this research will focus on the efficiency in the case of two fans with a high and a low power parallel. Stall will occur if the outside pressure is greater than the outlet pressure. Once the stall happens, the noise will increase suddenly, which will in turn result in fan vibration and running instability. When two fans parallel, i.e. when the power ratio of the parallel fans is over 5.3, the possibility of the small fan's stall is high, otherwise it is small. With regard to the running efficiency of parallel axial flow fans and the starting safety, it is better to parallel two fans, and the fans with adjustable movable vanes or frequency control or the ordinary nonadjustable fans can be used.

Forward Blade Sweep Applied to Low-Speed Axial Fan Rotors of Controlled Vortex Design: An Overview

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
János Vad
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Suction Side ◽  
Loss Reduction ◽  
Axial Fan ◽  
Flow Paths ◽  
Free Vortex ◽  
Low Speed ◽  
Cvd Method ◽  
Circulation Distribution

An overview is given on the research maintained by the author about the design aspects of three-dimensional blade passage flow in low-speed axial flow industrial fan rotors, affected by spanwise changing design blade circulation due to controlled vortex design (CVD), blade forward sweep (FSW), and their combination. It was pointed out that, comparing the CVD method to the free vortex design, the fluid in the blade suction side boundary layer has an increased inclination to migrate radially outward, increasing the near-tip blockage and loss. It was concluded that the benefit of FSW, in terms of moderating loss near the tip, can be better utilized for the rotors of the CVD, in comparison to the free vortex design. Compared to the free vortex design, the FSW applied to the blades of the CVD was found to also be especially beneficial in loss reduction away from the endwalls, via shortening the flow paths on the suction side—in any case being elongated by the radially outward flow due to CVD—and thus, reducing the effect of wall skin friction. The necessity of correcting the swept blades was pointed out for matching with the prescribed CVD circulation distribution.

Construction and Control of Surfaces via Deployable Mechanisms With Three Degrees of Freedom

2016 ◽  
Author(s):  
Shengnan Lu ◽  
Vishal Ramadoss ◽  
Dimiter Zlatanov ◽  
Xilun Ding ◽  
Matteo Zoppi
Keyword(s):  
Degrees Of Freedom ◽  
Large Scale ◽  
Three Dimensional ◽  
Large Scale Structures ◽  
Cad Models ◽  
Mechanical Networks ◽  
Scale Structures ◽  
And Control ◽  
Physical Boundary ◽  
Three Degrees Of Freedom

Applications of deployable mechanisms can be found in aeronautic and civil engineering, often in the creation of unfolding large-scale structures with curved surfaces. This paper proposes novel mechanical networks, which are used to approximate three-dimensional surfaces, such as cuboids, ellipsoids, or hyperboloids. Each such deployable structure is assembled from unit Sarrus and scissor linkages of different sizes, has several decoupled degrees of freedom, and can take any shape within a different family of parameterized surfaces. Each degree of freedom controls a separate parameter in the equation describing the physical boundary of the linkage network. The size and placement of the unit linkages and their elements are analyzed and selected for obtaining the expected families of surfaces. CAD models and kinematic simulations demonstrate the abilities of the mechanisms to perform dynamically the desired approximation.

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