• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.1-11
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• 2004

Numerical analyses on the aerodynamic characteristics of a counter rotating axial flow fan were conducted for the development of an axial type in-line duct fan. The counter rotating fan has a front rotor and a rear rotor which are counter rotating each other. Blade design of the counter rotating fan was done by extension of design method for axial flow fan which consists of rotor and stator blades. Through flow analysis was performed using matrix method which is applied for flow fields prediction of compressors or turbines. Aerodynamic characteristics and characteristic curves of the counter rotating fan were analyzed by expansion of the frequency domain panel method with duct modeling. Pressure losses were higher at leading edge and hub region of rotor blades. Characteristic curve of the counter rotating fan was overpredicted without consideration of viscous effect.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.3
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• pp.268-276
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• 2005

The aim of this paper is to suggest one efficient method for the various requirements of performance during the process designing and producing an impeller. The study considers that the revisions of a pitch angle of an impeller at an axial turbo fan affect an air flow rates and a static pressure rise. The axial turbo fan specified with the 250 Pa maximum static pressure and 1300 CMH fan air flow rates was tested and analyzed by CFD. The Numerical results show that the air flow rates are calculated to 1,175 CMH, 1,223 CMH, 1,270 CMH, 1,340 CMH and 800 CMH in cases that the pitch angles are $44^{\circ},\;49^{\circ},\;54^{\circ},\;59^{\circ},\;and\;64^{\circ}$ respectively. Also the static pressure rises are shown to 108 Pa, 122Pa, 141 Pa, 188 Pa and 63 Pa at the same cases. The air flow rate is increased linearly according to the changes of the pitch angle from $44^{\circ}\;to\;59^{\circ}$ and the maximum air flow rate passing the impeller is increased to $13\%$ over at the case of $59^{\circ}$ pitch angle compared with the reference case of $54^{\circ}$ pitch angle. The static pressure rise is increased linearly according to the changes of the pitch angle from $44^{\circ}\;to\;54^{\circ}$, too. The static pressure rise at the $59^{\circ}$ pitch angle is increased to $33\%$ over compared with the $54^{\circ}$ pitch angle. The result shows that the revisions of pitch angle make the static pressure rise increase widely. However the air flow rates and the static pressure rise at the $64^{\circ}$ pitch angle are suddenly decreased because of over-changed pitch angle.