• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.30-35
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• 2010

The aerodynamic performance of axial flow fans for outdoor unit of air-conditioner is investigated by numerical and experimental approaches in this study. The pressure drop and volumetric flow rate are compared each other in several different conditions and fan speeds. It is shown that the predicted fan performances are quite well matched with the experimental results. It is also shown that the curvature of the fan arc and hub height have significant influences on the flow distribution after hub. By the results of this study, it can be suggested that several ways to improve the aerodynamic performance of the axial flow fan can be found using the numerical analysis.

• The KSFM Journal of Fluid Machinery
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• v.13 no.2
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• pp.48-53
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• 2010

A computerized design system of axial fan is developed for constructing 3-D blade geometry and predicting both aerodynamic performance and noise. The aerodynamic blading design of fan is conducted by blade angle distribution, camber line determination, airfoil thickness distribution and blade element stacking along spanwise distance. The internal flow and the aerodynamic performance of designed fan are predicted by the through-flow modeling technique with flow deviation and pressure loss correlations. Based on the predicted internal flow field and performance data, fan noise is predicted by two models for discrete frequency and broadband noise sources. The present predictions of the flow distribution, the performance and the noise level of actual fans are well agreed with measurement results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.7
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• pp.674-679
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• 2000

The Sirocco fan performance and its three-dimensional flow characteristics were numerically predicted by STAR-CD software. Turbulent flow computations were performed using approximately 500,000 mesh points, and the performance results of two computational methods, transient analysis and quasi-static analysis were compared with experimental data. At present, our attention was focused on localizing the three-dimensional flow characteristics of the Sirocco fin, especially the structure of the secondary flow in the scroll and the through-flow characteristics of the Sirocco fan blades. Also, for an optimization, the scroll passage was tilted with 10 degrees to change the flow characteristics and improve the performance of the Sirocco fan.

• Journal of Mechanical Science and Technology
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• v.15 no.12
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• pp.1728-1738
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• 2001

Measurements have been made in an automotive HVAC b1ower for two different centrifugal fans. This work is directed at improving the performance of a conventional forward-curved centrifugal fan for a given small blower casing. Mean velocities and pressure have been measured using a miniature five-hole probe and a pressure scanning unit connected to an online data acquisition system. First, we obtained the fan performance versus flow rates showing a significant attenuation of unstable nature achieved with the new fan rotor in the surging operation range. Second, aerodynamic characterizations were carried out by investigating the velocity and pressure fields in the casing flow passage for different fan operating conditions. The measurements stowed that performance coefficients are strongly influenced by flow characteristics at the throat region. The main flow features ware common in both fans, but improved performance is achieved with tole new fan rotor, particularly in lower flow rate legions. Based on the measured results, design improvements were carried out in an acceptable operation range, which gave considerable insight into what features of flow behavior ware most important.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.1
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• pp.75-84
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• 2000

Performance and flow characteristics of a small forward swept propeller fan for home refrigerators are studied experimentally. An unusual discontinuity is observed in the performance curve of the fan. Mean flow fields measured with as-hole Pitot probe reveal that the flow is axial at the high flow rate and radial at the low flow rate. The flow structure changes abruptly across the discontinuity. Unsteady flow measurements with a set of hot-wire probes indicate that near the discontinuity a single-cell stall rotates at 40% speed of the fan speed, while away from the discontinuity the flow shows periodic variation corresponding to the blade passage frequency. Phase-lock averaged flow fields measured with a triple-sensor hot-wire probe show that there appears radially inward flow over the pressure side of the blade and the outward passage flow over the tip.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1586-1594
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• 1997

Performance characteristics of a small propeller fan are numerically investigated solving the continuity and Reynolds-averaged Navier-Stokes equations. The Reynolds stresses for turbulent transport are modelled using a k-.epsilon. turbulence model. The present numerical procedure is constructed using the Finite Volume Method with the SIMPLE algorithms. The performance parameters obtained from the calculations are compared with the measured values for the various flow rates. A performance test of the fan shows different characteristics between a radial type at small flow rates and an axial type at large flow rates. Comparisons between the predictions and the measurements show that the predicted results are in good agreement with the measured values and reasonably reproduce the sharp variations of the power and head coefficient around a flow coefficient .PHI.=0.3. These comparisons indicate that the present numerical method is capable of resolving the performance characteristics with reasonable accuracy. At low flow rates, it is found that the flow enters the fan in an axial direction and is discharged radially outward at the tip which happens in the centrifugal fan. The centrifugal effect makes a significant difference in the characteristics of a fan at the low and high values of flow coefficient.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.37-42
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• 2001

A computerized axial flow fan design system is developed with the capabilities for predicting the aerodynamic performance and the noise characteristics of fan. In the present study, the basic fan blading design is made by combining vortex distribution scheme with camber line design, airfoil selection, blade thickness distribution and stacking of blade elements. With the designed fan blade geometry, the through-flow field and the performance of fan are analyzed by using the streamline curvature computing scheme with spanwise total pressure loss and flow deviation models. Fan noise is assumed to be generated due to the pressure fluctuation induced by wake vortices of fan blades and to radiate as dipole distribution. The vortex-induced fluctuating pressure on blade surface is calculated by combining thin airfoil theory and the predicted flow field data. The predicted performances, sound pressure level and noise directivity patterns of fan by the present method are favorably compared with the test data of actual fans. Furthermore, the present method is shown to be very useful in designing the blade geometry of new fan and optimizing design variables of the fan to achieve higher efficiency and lower noise level.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.2076-2082
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• 2003

A cross-flow fan is widely used on many industrial fields: mining industry, automobile and home appliances, etc. The design point of the cross-flow fan is generally based on the region within low static pressure and high flow rate. It relatively makes high dynamic pressure at low speed because a working fluid passes through an impeller blade twice. However, it has low static pressure efficiency between 30% and 40% because of relative high impact loss. Recently, in the air-conditioning systems, the operating behaviors at the off-design points are highly regarded to broaden the application area for various air-cooling loads. Especially, at the lower flow rate, there exists a rapid pressure head reduction, a noise increase and an irregular flow field against a rearguider as a scroll of centrifugal fan. Numerical analyses are carried out for investigating the flow characteristics in a cross-flow fan including the impeller, the rearguider and the stabilizer. Especially, various types of rearguiders are estimated by numerical and experimental methods to insure the stable operation in the region of lower flow rate. Numerical domains are discretized by hexahedral cells. Three-dimensional, unsteady governing equations are solved using FVM, PISO algorithm, sliding grid system and standard ${\kappa}-{\varepsilon}$ turbulence model. ASHRAE standard fan tester is also used to estimate the performance of the modeled crossflow fan.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.541-547
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• 2000

Experiments were done for the comparison of performance and flow characteristics between a two stage axial flow fan and a counter-rotating axial flow fm. The fan performance curves were obtained by the Korean Standard Testing Methods for Turbo Fans and Blowers (KS B 6311). The fan flow characteristics were measured using a five-hole probe by the non-nulling method. Each stage of the two stage axial flow fan used for the present study has an eight bladed rotor and thirteen stator blades. The front and the rear rotor of the counter-rotating axial flow fan have eight blades each and are driven by coaxial counter rotating shafts through a gear box located between the rear rotor and the electric motor. Both of the two axial fan configurations use identical rotor blades and the same operating conditions for the one-to-one comparison of the two. Performance characteristics of the two configurations were obtained and compared by varying the blade setting angles and axial gaps between the blade rows. The passage flow fields between the hub and tip of the fans were measured and analyzed for the particular operating conditions of peak efficiency, minimum and maximum pressure coefficients.

• Korean Journal of Computational Design and Engineering
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• v.3 no.3
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• pp.201-209
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• 1998

To develop timely an optimal fan, a design system and a new manufacturing process used step by step have to be integrated. A small sized optimal fan for refrigerators, that was the goal on this project, was developed by the following principal processes. All processes are technologically linked in many directions: The existing fan was measured through reverse engineering. The measured data was used for the basic source of 3D design. The performance tests were carried and used as the data for the evaluation of the existing fan. Flow analysis by FANS-3D/sup [1]/ was performed at the given information (pressure drop and flow rate) to find out the configuration of optimal fan design. The flow patterns were investigated to measure the performance of fan through numerical experiment. The grid point data obtained by the above analysis turned into 3D high efficiency fan model by using CATIA. The product was manufactured by RP process (SLS, SLA) and tested the characteristic curves of the developed fan to compare with the existing fan. The modification of fan design were all examined to see any change in performance and checked to find any deficiency in assembling the fan into a duct. After the plastics flow analysis of the injection molding cycle to ensure acceptable quality fan, an optimal mold was processed by using tool-path for the newly designed fan.