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.

Computational Modeling of Low-Pressure Fan Flows

2000 ◽  
Author(s):  
Siddharth Thakur ◽  
Wanlai Lin ◽  
Jeffrey Wright ◽  
Wei Shyy ◽  
Ron Lievens
Keyword(s):  
Pressure Rise ◽  
Low Pressure ◽  
Flow Fields ◽  
Numerical Dissipation ◽  
Computational Tool ◽  
Axial Fan ◽  
Static Efficiency ◽  
Blade Shape ◽  
Axial Fans ◽  
Mass Flow Rates

A CFD-based computational tool is used to analyze flows in axial fans. Computed results for an axial fan flow field for one particular blade shape are presented; certain global quantities such as the mass-averaged pressure rise and the static efficiency available from test data for different mass flow rates are used to evaluate the trends predicted by the CFD results. The characteristic feature of the fan flow fields presented here is a very low pressure rise; due care is exercised to ensure that grid dependence and numerical dissipation do not smear out the key features of the computed flow fields.

Numerical Flow Analysis in a Subsonic Vaned Radial Diffuser With Leading Edge Redesign

1999 ◽  
Vol 121 (1) ◽  
pp. 119-126 ◽  
Author(s):  
E. Casartelli ◽  
A. P. Saxer ◽  
G. Gyarmathy
Keyword(s):  
Static Pressure ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Leading Edge ◽  
Inverse Design ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Characteristic Lines ◽  
Design Software

The flow field in a subsonic vaned radial diffuser of a single-stage centrifugal compressor is numerically investigated using a three-dimensional Navier–Stokes solver (TASCflow) and a two-dimensional analysis and inverse-design software package (MISES). The vane geometry is modified in the leading edge area (two-dimensional blade shaping) using MISES, without changing the diffuser throughflow characteristics. An analysis of the two-dimensional and three-dimensional effects of two redesigns on the flow in each of the diffuser subcomponents is performed in terms of static pressure recovery, total pressure loss production, and secondary flow reduction. The computed characteristic lines are compared with measurements, which confirm the improvement obtained by the leading edge redesign in terms of increased pressure rise and operating range.

An Analysis of the Loss Mechanisms in Low-Speed Axial Fans Using Scaling Arguments and Their Effects on a Proposed New Definition of Efficiency

2006 ◽  
Author(s):  
Douglas R. Neal
Keyword(s):  
Energy Equation ◽  
Pressure Rise ◽  
Axial Fan ◽  
Low Speed ◽  
Static Efficiency ◽  
Axial Fans ◽  
Integral Energy ◽  
Definition Of ◽  
Scaling Arguments ◽  
Ventilation Fan

Low-speed axial fans are used extensively for ventilation purposes in industrial and commercial buildings. In agricultural applications, such as a greenhouse, the ventilation is critical, since entire crops can be damaged or destroyed if a clean air supply is not maintained. The cost-marginal nature of these businesses demand that operating costs be kept to a minimum, hence there is a strong motivation to develop higher efficiency ventilation fans. An analysis of a low-speed axial fan has been developed using a control volume-based energy balance. The specific fan is an axial ventilation fan that is commonly found on agricultural facilities such as green-houses or livestock buildings. These fans induce an airflow from a large building into the open atmosphere at very low (or often effectively zero) system restriction or pressure rise. The definition for static efficiency, which is commonly used by the axial fan community, is examined and its implications are discussed. Since static efficiency yields a zero-percent efficient fan at a zero pressure rise operating condition, the ventilation fan industry has developed an alternate definition of efficiency. This alternate definition of efficiency, along with other proposed definitions, are described and their limitations are discussed. A new definition of efficiency is introduced and its basis in the integral energy equation is identified. The primary loss mechanisms of low-speed axial turbomachinery are discussed and scaling arguments are developed and used in the integral energy equation analysis. The results of this analysis yield an expanded expression of efficiency in which the loss mechanism terms can be empirically determined. When analyzed with values for a particular fan system, these results can further be used as the basis for an optimization study of that fan system.

scholarly journals Numerical Modeling and Optimization of an Air Handling Unit

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 68
Author(s):  
José Lopes ◽  
João Silva ◽  
Senhorinha Teixeira ◽  
José Teixeira
Keyword(s):  
Static Pressure ◽  
Pressure Rise ◽  
Solution Concept ◽  
Axial Component ◽  
Air Handling Unit ◽  
Control Units ◽  
Air Handling Units ◽  
Additional Improvement ◽  
Computational Fluid Dynamics Cfd ◽  
Air Conditioning Systems

Concerns about the efficiency of Heating, Ventilating, and Air Conditioning systems, including Air Handling Units (AHUs), started in the last century due to the energy crisis. Thenceforth, important improvements on the AHUs performance have emerged. Among the various improvements, the control of the AHUs and the redesign of the fans are the most important ones. Although, with increasingly demanding energy efficiency requirements, other constructive solutions must be investigated. Therefore, the objective of this work is to investigate, using a computational fluid dynamics (CFD) tool, the fluid flow inside an AHU and to analyze different constructive solutions in order to improve the AHU performance. The numerical model provided a reasonable agreement with the experimental results in terms of air flow rate, despite the assumed simplifications. Regarding the constructive solution concept, the CFD results for the two different flow control units (FCUs) showed improvements in terms of fan static pressure rise. Under real conditions, improvements of 15.1% when compared with the case without the FCU were obtained. Nevertheless, it was concluded that the axial component of the air velocity, at the fan exit, can have a determinant impact on the FCU viability. Finally, an improved FCU geometry, with a new body shape, which resulted in an additional improvement of 6.1% in the fan static pressure rise.

Flow Analysis in a Pump Diffuser—Part 2: Validation and Limitations of CFD for Diffuser Flows

1997 ◽  
Vol 119 (4) ◽  
pp. 978-984 ◽  
Author(s):  
F. A. Muggli ◽  
K. Eisele ◽  
M. V. Casey ◽  
J. Gu¨lich ◽  
A. Schachenmann
Keyword(s):  
Turbulence Model ◽  
Flow Separation ◽  
Static Pressure ◽  
Flow Analysis ◽  
Measurement Data ◽  
Pressure Rise ◽  
Pressure Recovery ◽  
Navier Stokes ◽  
Vaned Diffuser ◽  
Highly Loaded

This paper describes an investigation into the use of CFD for highly loaded pump diffuser flows. A reliable commercial Navier-Stokes code with the standard k-ε turbulence model was used for this work. Calculations of a simple planar two-dimensional diffuser demonstrate the ability of the k-ε model to predict the measured effects of blockage and area ratio on the diffuser static pressure recovery at low loading levels. At high loading levels with flow separation the k-ε model underestimates the blockage caused by the recirculation in the flow separation region and overestimates the pressure recovery in the diffuser. Three steady-state calculations of a highly loaded vaned diffuser of a medium specific speed pump have been carried out using different inlet boundary conditions to represent the pump outlet flow. These are compared to LDA measurement data of the flow field and demonstrate that although the Navier-Stokes code with the standard k-ε turbulence model is able to predict the presence of separation in the flow, it is not yet able to accurately predict the static pressure rise of this highly loaded pump diffuser beyond the flow separation point.

A Numerical Investigation of the Unsteady Flow in Centrifugal Stages

2000 ◽  
Author(s):  
Martin Peeters ◽  
Mohamad Sleiman
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Centrifugal Stage ◽  
Plane Analysis ◽  
Important Interaction ◽  
Computational Fluid Dynamics Cfd ◽  
Effective Use ◽  
Stage Analysis ◽  
Vane Diffuser

Computational Fluid Dynamics (CFD) has matured to the point where it can now be used effectively in impeller and diffuser design. The effective use of CFD for a complete centrifugal stage, however, still remains a challenge. The interaction between an impeller and its diffuser is not well understood and the level of modelling required to explain it is not really known. The goal of this paper is to present some results that can aid in this understanding. A numerical scheme is outlined that is capable of both steady and unsteady stage analysis. Results are presented for a stage consisting of an impeller and pipe diffuser using steady mixing plane analysis. Furthermore, unsteady results for a centrifugal stage consisting of an impeller and a vane diffuser are presented and compared to isolated steady analyses of each component. The results indicate that centrifugal stage performance is not well predicted using steady analysis. Differences in both the diffuser static pressure rise and the impeller pressure ratio are significant and it may be concluded that steady analysis is too unreliable for centrifugal stage predictions. Unsteady results also captured an important interaction phenomenon observed experimentally.

scholarly journals Numerical Flow Analysis in a Subsonic Vaned Radial Diffuser With Leading Edge Redesign

1997 ◽  
Author(s):  
E. Casartelli ◽  
A. P. Saxer ◽  
G. Gyarmathy
Keyword(s):  
Static Pressure ◽  
Flow Analysis ◽  
Pressure Rise ◽  
Leading Edge ◽  
Inverse Design ◽  
Navier Stokes ◽  
Characteristic Lines ◽  
3D Effects ◽  
Design Software ◽  
2D And 3D

The flow field in a subsonic vaned radial diffuser of a single stage centrifugal compressor is numerically investigated using a 3D Navier-Stokes solver (TASCflow) and a 2D analysis & inverse-design software package (MISES). The vane geometry is modified in the leading edge area (2D blade shaping) using MISES, without changing the diffuser throughflow characteristics. An analysis of the 2D and 3D effects of two redesigns on the flow in each of the diffuser subcomponents is performed in terms of static pressure recovery, total pressure loss production and secondary flow reduction. The computed characteristic lines are compared with measurements, which confirm the improvement obtained by the leading edge redesign in terms of increased pressure rise and operating range.

Blade Sweep for Low-Speed Axial Fans

1989 ◽  
Author(s):  
Terry Wright ◽  
William E. Simmons
Keyword(s):  
Volume Flow Rate ◽  
Pressure Rise ◽  
Design Procedure ◽  
Acoustic Properties ◽  
Excess Noise ◽  
Axial Fan ◽  
Low Speed ◽  
Axial Fans ◽  
Computer Codes ◽  
Selection Of

The available literature on aerodynamic and acoustic properties of axial fans with swept blades is presented and discussed with particular emphasis on noise mechanisms and the influence of high-intensity inlet turbulence on “excess” noise. The acoustic theory of Kerschen and Envia for swept cascades is applied to the problem of axial fan design. These results are compared to available data and a provisional model for specifying sweep angles is presented. The aerodynamic performance theory for swept-bladed rotors of Smith and Yeh is adapted for use in designing low speed axial fans. Three prototype fans were designed using the resultant computer codes. One is a baseline fan with blade stacking lines radially oriented, and two are fans having swept blades of increasingly greater forward sweep. Aerodynamic testing shows that performance of the fans lie within a band width of about ± two percent of volume flow rate and pressure rise predictions in the region of design performance, effectively validating the design procedure for selection of the blading parameters. Noise testing of the fans was carried out and the results show an average noise reduction for the swept-bladed fans of about 7 dBA overall, and a reduction of pure tone noise at blade-pass frequency of about 10 dB compared to the zero-sweep baseline model in close agreement with the theory of Kerschen and Envia.

scholarly journals Three-Dimensional Navier-Stokes Analysis and Redesign of an Imbedded Bellmouth Nozzle in a Turbine Cascade Inlet Section

1994 ◽  
Author(s):  
P. W. Giel ◽  
J. R. Sirbaugh ◽  
I. Lopez ◽  
G. J. Van Fossen
Keyword(s):  
Static Pressure ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Inlet Section ◽  
Turbine Cascade ◽  
Blade Cascade ◽  
Inlet Geometry ◽  
Computational Fluid Dynamics Cfd ◽  
Transonic Turbine

Experimental measurements in the inlet of a transonic turbine blade cascade showed unacceptable pitchwise flow non-uniformity. A three-dimensional, Navier-Stokes computational fluid dynamics (CFD) analysis of the imbedded bellmouth inlet in the facility was performed to identify and eliminate the source of the flow non-uniformity. The blockage and acceleration effects of the blades were accounted for by specifying a periodic static pressure exit condition interpolated from a separate three-dimensional Navier-Stokes CFD solution of flow around a single blade in an infinite cascade. Calculations of the original inlet geometry showed total pressure loss regions consistent in strength and location to experimental measurements. The results indicate that the distortions were caused by a pair of streamwise vortices that originated as a result of the interaction of the flow with the imbedded bellmouth. Computations were performed for an inlet geometry which eliminated the imbedded bellmouth by bridging the region between it and the upstream wall. This analysis indicated that eliminating the imbedded bellmouth nozzle also eliminates the pair of vortices, resulting in a flow with much greater pitchwise uniformity. Measurements taken with an installed redesigned inlet verify that the flow non-uniformity has indeed been eliminated.

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