Morphing of Reversible Axial Fan Blade: A FSI-FEM Study

2021 ◽  
Author(s):  
Valerio F. Barnabei ◽  
Alessio Castorrini ◽  
Alessandro Corsini ◽  
Franco Rispoli
Keyword(s):  
Research Effort ◽  
Elastic Solid ◽  
Navier Stokes ◽  
Design Solution ◽  
Axial Fan ◽  
Navier Stokes Equation ◽  
Linear Elastic ◽  
Axial Fans ◽  
Fan Blade ◽  
Dynamics Simulations

Abstract Reversible axial fans are widely used in industrial and tunnel ventilation systems, and a lot of research effort is spent in the design process of the blades shape and blades profile. The target is to achieve reasonable performances in both flow directions, but those are still below the levels of the corresponding non-reversible geometries. In this paper, an alternative design solution for reversible axial fan is presented by adopting flexible blades instead of the rigid ones. Such design, inspired by the boat sails, could allow the blade to change its shape by passively adapting to the flow field, from a symmetrical blade profile to a not symmetric one, and thus adapting the curvature to the flow condition. In the paper, a series of alternative materials and material distributions are analysed and compared. The analysis is conducted by performing Fluid-Structure Interaction simulations using stabilized Finite Elements formulations for both the fluid and the structure dynamics. Simulations are performed using the in-house built software FEMpar, which implements the Residual Based Variational MultiScale to model the Navier-Stokes equation, the Total Lagrangian formulation for the non-linear elastic solid and the Solid Extension Moving Mesh Technique to move the fluid mesh.

A Ring Silencer Design for Reducing Noise of Axial Fan

2003 ◽  
Vol 03 (03) ◽  
pp. L259-L264
Author(s):  
Jian-Da Wu ◽  
Mingsian R. Bai
Keyword(s):  
Helmholtz Resonator ◽  
Boundary Region ◽  
Acoustic Analogy ◽  
Axial Fan ◽  
Noise Sources ◽  
Fan Noise ◽  
Fluctuating Pressure ◽  
Axial Fans ◽  
Fan Blade ◽  
Broadband Frequency

In this paper, a ring silencer design for reducing the noise of axial fans is presented. The noise sources on axial fans are usually caused by the fluctuating pressure distribution on the surface of fan blade. Most of the sources are near the trailing edge of blades or boundary region of blades. The ideation of proposed design is based on the principle of Helmholtz resonator for reducing the noise around the fan. The electro-acoustic analogy of this design is presented and simply discussed. Experimental measurement is carried out to evaluate the proposed design for reducing the axial fan noise. The result of experiment indicated that the ring silencer achieved 17 dB in blade passing frequency and 10 dB in other broadband frequency of power spectrum level.

Development of Autonomous Design Technique for Axial Fans Using Numerical Optimization

2005 ◽  
Author(s):  
Taku Iwase ◽  
Kazuyuki Sugimura ◽  
Taro Tanno
Keyword(s):  
Numerical Optimization ◽  
Simulated Annealing Algorithm ◽  
Static Pressure ◽  
Pressure Rise ◽  
Navier Stokes ◽  
Axial Fan ◽  
Automatic Program ◽  
Axial Fans ◽  
Computational Fluid Dynamics Cfd ◽  
Annealing Algorithm

We designed an axial fan for servers using computational fluid dynamics (CFD) and numerical optimization. The performance of the fan, namely static pressure rise and efficiency, was calculated using commercial CFD software based on an incompressible Reynolds-averaged Navier-Stokes (RANS) solver. An automatic program developed in-house was used to generate the grids for CFD calculation. Numerical optimization—using a simulated annealing algorithm (SA)—was used for determining the optimized shape of the fan. After optimizing the fan, initial and optimized fan designs were made for experiments using rapid prototyping, and their performances, based on such things as efficiency and noise level, were measured. Results demonstrated that the optimized fan design achieved higher efficiency than the initial design. Multi optimization was also developed for maximizing the fan efficiency and minimizing the casing height. An additional finding was that there was a trade-off between the fan efficiency and casing height.

scholarly journals Shape control and compartmentalization in active colloidal cells

2015 ◽  
Vol 112 (34) ◽  
pp. E4642-E4650 ◽  
Author(s):  
Matthew Spellings ◽  
Michael Engel ◽  
Daphne Klotsa ◽  
Syeda Sabrina ◽  
Aaron M. Drews ◽  
...  
Keyword(s):  
Mirror Symmetry ◽  
Shape Control ◽  
Navier Stokes ◽  
Distributed Energy ◽  
Navier Stokes Equation ◽  
Entire Volume ◽  
Autonomous Machines ◽  
Matter System ◽  
Dynamics Simulations ◽  
Over Time

Small autonomous machines like biological cells or soft robots can convert energy input into control of function and form. It is desired that this behavior emerges spontaneously and can be easily switched over time. For this purpose we introduce an active matter system that is loosely inspired by biology and which we term an active colloidal cell. The active colloidal cell consists of a boundary and a fluid interior, both of which are built from identical rotating spinners whose activity creates convective flows. Similarly to biological cell motility, which is driven by cytoskeletal components spread throughout the entire volume of the cell, active colloidal cells are characterized by highly distributed energy conversion. We demonstrate that we can control the shape of the active colloidal cell and drive compartmentalization by varying the details of the boundary (hard vs. flexible) and the character of the spinners (passive vs. active). We report buckling of the boundary controlled by the pattern of boundary activity, as well as formation of core–shell and inverted Janus phase-separated configurations within the active cell interior. As the cell size is increased, the inverted Janus configuration spontaneously breaks its mirror symmetry. The result is a bubble–crescent configuration, which alternates between two degenerate states over time and exhibits collective migration of the fluid along the boundary. Our results are obtained using microscopic, non–momentum-conserving Langevin dynamics simulations and verified via a phase-field continuum model coupled to a Navier–Stokes equation.

PARTICLE DYNAMICS SIMULATIONS OF THE NAVIER–STOKES FLOW WITH HARD DISKS

2004 ◽  
Vol 15 (10) ◽  
pp. 1413-1424 ◽  
Author(s):  
TATSUYA ISHIWATA ◽  
TERUYOSHI MURAKAMI ◽  
SATOSHI YUKAWA ◽  
NOBUYASU ITO
Keyword(s):  
Equations Of Motion ◽  
Local Equilibrium ◽  
Flow Simulation ◽  
Quantitative Agreement ◽  
Particle Dynamics ◽  
Navier Stokes ◽  
Hard Disks ◽  
Navier Stokes Equation ◽  
Dynamics Simulations ◽  
Energy And Momentum

Flow simulation with a particle dynamics method is studied. The fluid is made of hard particles which obey the Newtonian equations of motion and the collisions between particles are elastic, that is, energy and momentum are conserved. The viscosity appears autonomously together with the local equilibrium state. When a particle collides with a nonslip boundary, a new velocity is given randomly from the thermal distribution if the wall is isothermal, or a random reflection angle is selected if the wall is adiabatic. Shear viscosity is estimated from simulations of plane Poiseuille flow together with the confirmation that the system obeys the Navier–Stokes equation. Flows past a cylinder are also simulated. Depending on the Reynolds number up to 106, flow patterns are properly reproduced, and Kármán vortex shedding is observed. The estimated values of drag coefficient show quantitative agreement with experiments.

Axial Fan Blade Tone Cancellation Using Optimally Tuned Quarter Wavelength Resonators

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Lee Gorny ◽  
Gary H. Koopmann
Keyword(s):  
Sound Field ◽  
Test Facility ◽  
Secondary Source ◽  
Axial Fan ◽  
Ducted Fan ◽  
Quarter Wavelength ◽  
Centrifugal Fans ◽  
Line Theory ◽  
Axial Fans ◽  
Fan Blade

Fan noise challenges noise control engineers in developing products ranging in scale from small ventilation systems to large turbomachines. The dominant noise source in many axial fans is the tonal noise due to rotor/stator interactions at the fundamental blade passing frequency. Flow-excited resonators have been used in the past for minimizing blade tone sound pressure levels (SPLs) generated by centrifugal fans through means of secondary source cancellation. The focus of this research is to extend that cancellation method to axial fans by attaching flow-driven quarter wavelength resonators fitted with optimal mouth perforations around the perimeter of the fan’s shroud. A ducted-fan test facility was developed to measure upstream and downstream noise radiated from a test fan. Resonators were mounted at specific locations around the fan’s shroud to obtain reductions in blade tone SPLs in both flow directions. They were driven into resonance via the unsteady pressure from the passing blades. An analytical model using transmission line theory was developed and validated experimentally to characterize the resonator’s behavior under various flow conditions and mouth geometries. This model was used to predict the resonator’s potential for reducing in-duct blade tones for specific flows and mouth perforation patterns. In a series of experiments to obtain the optimal resonator mouth perforations, it was observed that upstream and downstream SPL attenuations require different placement of the resonator mouth relative to the blade of the fan. With a single tuned resonator it was demonstrated that the fundamental blade tone SPLs can be reduced by as much as 20 dB in either the upstream or the downstream duct but not in both directions simultaneously. This behavior results when combining the resonator’s monopolelike sound field with the dipolelike sound field of the fan’s blades. Further studies are underway to extend the above method to higher pressure fans operating at speeds that generate higher order duct modes.

scholarly journals Strength Analysis of a Ducted Axial Fan Blade

2018 ◽  
Vol 9 (4) ◽  
pp. 85-100
Author(s):  
Marek ROŚKOWICZ ◽  
Ryszard CHACHURSKI ◽  
Sławomir TKACZUK ◽  
Piotr LESZCZYŃSKI ◽  
Maciej MAJCHER ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Numerical Calculations ◽  
Strength Analysis ◽  
Axial Fan ◽  
Optical Scanner ◽  
Geometrical Features ◽  
Simplifying Assumptions ◽  
Axial Fans ◽  
Fan Blade ◽  
And Performance

This paper presents a numerical strength analysis of a ducted axial fan blade. Ducted axial fans are a large group of fluid-flow machines. The analysis was designed to determine the causes of cyclic failures of a ventilation unit. The paper presents a reverse engineering approach to the mapping of the fan blade’s geometrical features. The geometrical features were mapped by triangulation from the scanning images produced by a 3D optical scanner. These were followed by simplifying assumptions on which the numerical calculations were based. The numerical calculations were carried out at the operating rotational speeds of the ducted axial fan’s rotor. The course of the numerical calculations is described, and their results are also presented herein. The results are represented on colour maps of stress distribution for selected structural elements of the fan blade. The stress distribution at a blade cross-section was compared to CT scans of the fractures of failed rotor blade airfoils. Final conclusions were developed which show that the design engineering process of fans should feature optimisation of the fan’s efficiency, including the strength and performance parameters, which should include the service life of the fan.

Numerical Study on the Passive Control of the Aeroelastic Response in Large Axial Fans

2016 ◽  
Author(s):  
A. Castorrini ◽  
A. Corsini ◽  
A. G. Sheard ◽  
F. Rispoli
Keyword(s):  
Passive Control ◽  
Numerical Study ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Axial Fan ◽  
Strongly Coupled ◽  
Dimensional Approximation ◽  
Axial Fans ◽  
Fan Blade ◽  
And Performance

The morphing geometry concept finds interesting applications in load reduction and performance increasing for wings and rotor blades in off-design conditions. Here we report a numerical study on the effect that a passive morphing system (made by an elastic-low stiffness surface) has on the sectional load and flowfield, when it is applied to the trailing edge of an axial fan. We obtain the results extracting the section of the fan blade and test it in the 2D cascade, with and without the elastic device, in different operating conditions. Keeping in mind the two-dimensional approximation, it will be possible to observe how the tested device could reduce the load in off-design and high angle of attack conditions, while the same solution could introduce vibrations in design conditions. All the simulations imply the solution of the fluid-structure interaction between the incompressible, turbulent flow and the elastic structure. This solution is obtained using a finite element based, strongly coupled solver, applied to the periodic 2D domain of the section in the cascade.

Shape Optimisation of Axial Fan Blades Using Genetic Algorithms and a 3D Navier-Stokes Solver

2006 ◽  
Author(s):  
O. Lotfi ◽  
J. A. Teixeira ◽  
P. C. Ivey ◽  
I. R. Kinghorn ◽  
A. G. Sheard
Keyword(s):  
Genetic Algorithm ◽  
Thickness Distribution ◽  
Three Dimensional ◽  
Automated Design ◽  
Navier Stokes ◽  
Shape Optimisation ◽  
Axial Fan ◽  
Optimization Task ◽  
Blade Thickness ◽  
Fan Blade

The paper describes the development of an automated design process which was developed to aerodynamically optimise an industrial fan blade geometry taking account of the predicted three dimensional flow. The optimiser employs a genetic algorithm for global optimisation purposes and is coupled to the academic Navier-Stokes solver MULTIP. The optimization task is accomplished by modifying the blade camber line, lean and sweep while keeping the blade thickness distribution and mass flow rate, constant. A number of different configurations have been studied and the behaviour of genetic algorithm tested. Specific interfaces were developed in order to link the optimization code, the automatic grid generator STAGEN, utilised to define the computational meshes, and the three-dimensional Navier-Stokes solver within an automated design loop. The results obtained show that the genetic algorithm when coupled to a CFD tool is not only capable of achieving an improvement in the designs of existing axial fan blades effectively but also that they achieve these results with a minimum amount of user expertise.

A simple hydromechanical approach for simulating squirt-type flow

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. D335-D344 ◽  
Author(s):  
Beatriz Quintal ◽  
J. Germán Rubino ◽  
Eva Caspari ◽  
Klaus Holliger
Keyword(s):  
Fluid Flow ◽  
Spatial Patterns ◽  
Elastic Solid ◽  
Viscous Friction ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Perfect Agreement ◽  
Type Flow ◽  
The Difference ◽  
Biot’S Equations

The deformations caused by an acoustic wavefield in subsurface rock can induce fluid flow within hydraulically interconnected mesoscopic fractures, from one fracture into the other. The viscous friction associated with this squirt-type fluid flow parallel to the fracture walls results in energy dissipation and velocity dispersion. We have developed a quasi-static hydromechanical approach that is suitable for simulating squirt-type flow in the mesoscopic scale range and microscopic squirt flow. Our approach couples Navier-Stokes equation with Hooke’s law to describe the laminar flow of a viscous compressible fluid in conduits embedded in an elastic solid background. Results from the proposed method were compared with those obtained with Biot’s equations for a model containing interconnected mesoscopic fractures embedded in a background of very low porosity and permeability. Despite significant differences in the flow and dissipation spatial patterns, we have observed an essentially perfect agreement of the attenuation and modulus dispersion characteristics predicted by the two approaches. The difference in the flow and dissipation spatial patterns are associated with the “upscaling” inherent to Biot’s equations and, correspondingly, with differing boundary conditions at the fracture walls. Our results demonstrate that the proposed hydromechanical approach can provide additional insights on the physics of squirt-type flow in the mesoscopic and microscopic scale ranges.

scholarly journals Computational Fluid Dynamics Simulations of Aerodynamic Performance of Low-Pressure Axial Fans With Small Hub-to-Tip Diameter Ratio

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Jie Wang ◽  
Niels P. Kruyt
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulence Model ◽  
Aerodynamic Performance ◽  
Diameter Ratio ◽  
Trailing Edge ◽  
Axial Fans ◽  
Computational Fluid Dynamics Simulations ◽  
Fan Blade ◽  
Dynamics Simulations

Abstract Rotor-only ducted axial fans with small hub-to-tip diameter ratio are widely used in many branches of industry, especially for cooling and ventilation purposes. For such fans, extensive regions of backflow are present downstream of the fan near the hub. Only few computational fluid dynamics (CFD) studies for such fans have been reported in the scientific literature. In order to develop guidelines for obtaining accurate CFD predictions for such fans, validation simulations of a fan with small hub-to-tip diameter ratio have been performed by comparing experimental and computed aerodynamic performance characteristics. These guidelines pay special attention to the trailing edge shape, presence of nonaerodynamically shaped blade sections, tip gap, and employed turbulence model. The results for the fan studied here show that the actual (rounded) trailing edge is necessary; the main blade (without nonaerodynamically shaped blade sections) well represents the aerodynamic performance of the whole fan blade; it is recommended not to take the tip gap into consideration due to the existence of significant flow separation; the use of the Spalart–Allmaras turbulence model is advised for giving better agreement with measurements.

Sign in / Sign up

Export Citation Format

Share Document