A Simple Method for the Selection of Axial Fan Blade Profiles

1978 ◽  
Vol 192 (1) ◽  
pp. 269-275 ◽  
Author(s):  
N. Hay ◽  
R. Metcalfe ◽  
J. A. Reizes
Keyword(s):  
Design Method ◽  
Axial Flow ◽  
Operating Conditions ◽  
Angle Of Incidence ◽  
Axial Fan ◽  
Simple Method ◽  
Camber Angle ◽  
Fan Blade ◽  
Existing Data ◽  
Selection Of

Existing data on aerofoil sections suitable for axial flow fans are replotted on axes of angle of incidence against camber angle. The carpet plots so obtained permit the best operating conditions for each type of aerofoil to be immediately identified and thus the most suitable section can be easily selected for a given specification. A design method based on the use of these carpet plots is proposed and illustrated with a numerical example.

Parmeterization of the Total Pressure Distribution Along a Low-Pressure Axial Fan Blade According to the Design Requirements

2008 ◽  
Author(s):  
Maria Pascu ◽  
Philipp Epple ◽  
Antonio Delgado ◽  
Franz Durst
Keyword(s):  
Total Pressure ◽  
Design Method ◽  
Flow Characteristics ◽  
Axial Flow ◽  
Critical Parameters ◽  
Design Strategies ◽  
Axial Fan ◽  
Absolute Increase ◽  
Overall Performance ◽  
Fan Blade

In the field of axial flow turbomachines, the two–dimensional cascade model is often used experimentally or numerically to investigate fundamental flow characteristics and overall performance of the impeller. The core of the present work is a design method for axial fan cascades aiming to derive inversely the optimum blade shape based on the requirements of the impeller and not using any predefined airfoil profiles. While most design strategies based on the airfoil theory assume constant total pressure at all streamlines, i.e. free–vortex flow, this paper investigates the possibility of varying the total pressure along the blade and based on that, an analytical expression of the outlet blade angle is determined. When computing the blade profile at specified radius, critical parameters reflecting on the flow characteristics are observed and adjusted, i.e. sufficient lift and controlled deceleration of the flow on the contour so that the resulting profile is derived for minimum losses. The validation of this design strategy is given by the numerical results obtained when employed as an optimization tool for an industrial fan: 10–20% absolute increase in the efficiency of the optimized impeller.

scholarly journals Analytical and numerical investigation of the optimum pressure distribution along a low-pressure axial fan blade

2008 ◽  
Vol 223 (3) ◽  
pp. 643-657 ◽  
Author(s):  
M Pascu ◽  
M Miclea ◽  
P Epple ◽  
A Delgado ◽  
F Durst
Keyword(s):  
Total Pressure ◽  
Design Method ◽  
Flow Characteristics ◽  
Axial Flow ◽  
Critical Parameters ◽  
Design Strategies ◽  
Axial Fan ◽  
Optimum Pressure ◽  
Absolute Increase ◽  
Fan Blade

In the field of axial flow turbomachines, the two-dimensional cascade model is often used experimentally or numerically to investigate fundamental flow characteristics and overall performance of the impeller. The core of the present work is a design method for axial fan cascades aiming to derive inversely the optimum blade shape based on the requirements of the impeller and not using any predefined aerofoil profiles. While most design strategies based on the aerofoil theory assume constant total pressure at all streamlines, i.e. free-vortex flow, this paper investigates the possibility of varying the total pressure along the blade and based on that, an analytical expression of the outlet blade angle is determined. When computing the blade profile at a specified radius, critical parameters reflecting on the flow characteristics are observed and adjusted (i.e. sufficient lift and controlled deceleration of the flow on the contour) so that the resulting profile is derived for minimum losses. The validation of this design strategy is given by the numerical results obtained when employed as an optimization tool for an industrial fan: 10–20 per cent absolute increase in the static efficiency of the optimized impeller.

scholarly journals Measurement and Prediction of Tip Leakage Losses in an Axial-Flow Transonic Turbine

1997 ◽  
Author(s):  
M. Wehner ◽  
J. Bütikofer ◽  
C-W. Hustad ◽  
A. Bölcs
Keyword(s):  
Flow Analysis ◽  
Axial Flow ◽  
Suction Side ◽  
Angle Of Incidence ◽  
Simple Method ◽  
Flow Angle ◽  
Tip Leakage ◽  
Gap Height ◽  
Exit Mach Number ◽  
Annular Cascade

This paper presents a simple method for predicting tip leakage losses in transonic axial-flow turbines. The method is based upon experimental work conducted on a flat plate at 5° incidence and with isentropic exit Mach number of 1.26. The tip gap height was varied from zero up to 15% of chord. Measurements were made (using Laser-2-Focus) of velocity vectors around the tip gap region. These revealed a strong shear layer emerging from the gap onto the suction side of the plate. The relative angle between the leakage flow and the freestream was identified as a key parameter determining the subsequent mixing and overall loss generation. The proposed model applies two-dimensional potential flow analysis to estimate the flow angle as a function of tip gap height and the angle of incidence. Subsequently, comparisons were made with experimental results obtained in an annular cascade on the outer profile of the last-stage blade of a steam turbine. The predicted tip leakage losses compare favourably with the measured values.

scholarly journals Preliminary Design Guidelines for Considering the Vibration and Noise of Low-Speed Axial Fans Due to Profile Vortex Shedding

2022 ◽  
Vol 7 (1) ◽  
pp. 2
Author(s):  
Gábor Daku ◽  
János Vad
Keyword(s):  
Vortex Shedding ◽  
Design Method ◽  
Axial Flow ◽  
Design Guidelines ◽  
Worst Case ◽  
Low Speed ◽  
Increased Risk ◽  
Axial Fans ◽  
Fan Blade ◽  
Set Up

This paper presents a critical overview on worst-case design scenarios for which low-speed axial flow fans may exhibit an increased risk of blade resonance due to profile vortex shedding. To set up a design example, a circular-arc-cambered plate of 8% relative curvature is investigated in twofold approaches of blade mechanics and aerodynamics. For these purposes, the frequency of the first bending mode of a plate of arbitrary circular camber is expressed by modeling the fan blade as a cantilever beam. Furthermore, an iterative blade design method is developed for checking the risky scenarios for which spanwise and spatially coherent shed vortices, stimulating pronounced vibration and noise, may occur. Coupling these two approaches, cases for vortex-induced blade resonance are set up. Opposing this basis, design guidelines are elaborated upon for avoiding such resonance. Based on the approach presented herein, guidelines are also developed for moderating the annoyance due to the vortex shedding noise.

Experimental Study of the Effect of Serrations on Axial Flow Fan Blade Trailing Edge

2016 ◽  
Author(s):  
Dhyanjyoti Deb Nath ◽  
K. Viswanath ◽  
Ankit Bhai Patel
Keyword(s):  
Axial Velocity ◽  
Pressure Sensors ◽  
Tangential Velocity ◽  
Axial Flow ◽  
Experimental Investigations ◽  
Spanwise Direction ◽  
Axial Fan ◽  
Trailing Edge ◽  
Trailing Edges ◽  
Fan Blade

Rotor wakes shed from a compressor rotor impinge on downstream blades and is a major source of rotor-stator interaction noise and much research has been dedicated on wake attenuation. Serrated trailing edges is one such wake attenuation technique where the vortices produced at the serrated trailing edges enhance mixing and create a more uniform flow at stator inlet. The present paper investigates the effect of serrations on the trailing edge of a forced vortex axial fan blade. Experimental investigations were carried out at rotor outlet using pneumatic probes and fast response pressure sensors. It is found that total and static pressures reduce in serrated blades due to reduced turning and hence reduced work input. The absolute tangential velocity wake deficit decreases in serration valleys and improvement in axial velocity wake deficit is also found. Improvements as large as 19% and 18% decrease in absolute tangential velocity and axial velocity wake deficit are found at certain radii. The spanwise shape of the wake is altered by the serrations and a wake pattern undulating in the spanwise direction is observed. These are expected to bring down the circumferential variation of the velocity and its phase before entering the next row of blades and bring down the tonal noise.

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.

Experimental Investigation of the Effect of Reynolds Number on the Efficiency of Single-Stage Axial Fans

2018 ◽  
Author(s):  
Massimo Masi ◽  
Stefano Castegnaro ◽  
Andrea Lazzaretto
Keyword(s):  
Reynolds Number ◽  
Axial Flow ◽  
Operating Conditions ◽  
Single Stage ◽  
Axial Fan ◽  
Low Speed ◽  
Surface Finishes ◽  
Axial Fans ◽  
The Many ◽  
Testing Standards

Uncertainties surrounding the influence of Reynolds number on the performance of air handling turbomachines are as old as the study of turbomachinery fluid dynamics. In particular, all low-speed turbomachines and most axial-flow fans feature Reynolds numbers that are often lower than the critical value, above which the literature states a limited dependency of blades cascade aerodynamics on Reynolds number. Testing standards already account for this well-known issue, which arises mainly in the case of geometrically similar fans of different size and/or operating conditions. On the other hand, one of the main practical issues in the design of low-speed machines is the disagreement among the most authoritative sources on the value of the critical Reynolds number for axial fans. The many definitions of Reynolds number, which are suited to either fan design purposes or fan performance assessment, introduce additional problems, as the corresponding values may differ by orders of magnitude depending on the chosen definition. A less debated issue deals with the effect of Reynolds number on global performance and efficiency parameters for different axial-flow fan configurations. This paper reports pressure and efficiency data measured at several rotational speeds of four axial fans that feature different configurations, hub-to-tip ratios, sizes and surface finishes. In particular, the tests consider two 315mm and one 630mm tube-axial fans, and one 800mm vane-axial fan with preswirler blading. Data on two vane-axial fans with straightener, and one preswirler-rotor-stator stage, available in the literature, widen the discussion on the Reynolds number effect on the entire category of single-stage axial fans.

A Simple Method of Arriving at Control Structures for Multivariable Systems

1972 ◽  
Vol 5 (7) ◽  
pp. 284-287 ◽  
Author(s):  
F. P. Stainthorp
Keyword(s):  
Control Systems ◽  
Design Method ◽  
Multivariable Control ◽  
Multivariable Systems ◽  
Simple Method ◽  
Control Structures ◽  
Multivariable Control Systems ◽  
Relative Gain Array ◽  
Detailed Evaluation ◽  
Selection Of

Some properties of Bristol's “relative gain array” are discussed and it is shown that these lead to the selection of simple structures for multivariable control systems. A design method based on this approach helps the design engineer rapidly to select suitable structures for detailed evaluation.

scholarly journals Numerical Analysis of Erosion Caused by Biomimetic Axial Fan Blade

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Jun-Qiu Zhang ◽  
Zhi-Wu Han ◽  
Hui-Na Cao ◽  
Wei Yin ◽  
Shi-Chao Niu ◽  
...  
Keyword(s):  
Numerical Study ◽  
Axial Flow ◽  
Erosive Wear ◽  
Impact Angle ◽  
Continuous Phase ◽  
Solid Particles ◽  
Discrete Phase Model ◽  
Axial Fan ◽  
Wide Range ◽  
Fan Blade

Damage caused by erosion has been reported in several industries for a wide range of situations. In the present work, a new method is presented to improve the erosion resistance of machine components by biomimetic method. A numerical investigation of solid particle erosion in the standard and biomimetic configuration blade of axial fan is presented. The analysis consists in the application of the discrete phase model, for modeling the solid particles flow, and the Eulerian conservation equations to the continuous phase. The numerical study employs computational fluid dynamics (CFD) software, based on a finite volume method. User-defined function was used to define wear equation. Gas/solid flow axial fan was simulated to calculate the erosion rate of the particles on the fan blades and comparatively analyzed the erosive wear of the smooth surface, the groove-shaped, and convex hull-shaped biomimetic surface axial flow fan blade. The results show that the groove-shaped biomimetic blade antierosion ability is better than that of the other two fan blades. Thoroughly analyze of antierosion mechanism of the biomimetic blade from many factors including the flow velocity contours and flow path lines, impact velocity, impact angle, particle trajectories, and the number of collisions.

Sign in / Sign up

Export Citation Format

Share Document