• International Journal of Fluid Machinery and Systems
• /
• v.2 no.4
• /
• pp.449-455
• /
• 2009

A reversible axial flow fan called jet fan has been widely used for longitudinal ventilation in road tunnels to secure a safe and comfortable environment cost-effectively. As shifting the flow direction is usually made by only switching the rotational direction of an electric motor due to heavy duty, rotor blades having identical aerodynamic performance for bidirectional flow should be necessary. However, such aerodynamically desirable blades haven't been developed sufficiently, since most of the related studies have been done from the viewpoint of unidirectional flow. In the present paper, we demonstrate a method to profile the blade section suitable for bidirectional flow, which is validated by studying the aerodynamic performances of rotor blades of a two-stage jet fan experimentally and numerically.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.26 no.2
• /
• pp.67-71
• /
• 2014

In this study, a fan coil unit with an oval-type heat exchanger has been developed. The performance of the present fan coil unit has been investigated, by comparison with the previous fan coil unit with a circular-type heat exchanger. For the fan coil unit with circular- and oval-type heat exchangers, the heat flux and pressure loss through the heat exchangers were measured at standard operating conditions. In addition, the wind speeds exhausted from the fan coil units were compared, for the same fan motor operation. The experimental results show that the average wind speed of the oval-type heat exchanger is 20 percent higher than that of the circular-type heat exchanger. The heat flux in the oval-type heat exchanger is enhanced by 40% or more, over the circular-type heat exchanger.

• Proceedings of the KIEE Conference
• /
• 2004.10a
• /
• pp.120-122
• /
• 2004

In this Paper, high efficiency dual air-gap induction motor with permanent magnet rotor is described. The finite element method is used to design the rotor and magnet. And we presented the analysis, construction, experimental results of prototype single phase induction motor with permanent magnet rotor for air-conditioner fan motor.

• The KSFM Journal of Fluid Machinery
• /
• v.10 no.6
• /
• pp.7-16
• /
• 2007

An axial-type fan which operates at the relative total pressure of 671Pa and static pressure of 560Pa with the flow rate of $416.6m^3/min$ is developed with an optimization technique based on the gradient method. Prior to the optimization of fan blade, a three-dimensional axial-type fan blade is designed based on the free-vortex method along the radial direction. Twelve design variables are applied to the optimization of the rotor blade, and one design variable is selected for optimizing a stator which is located behind of the rotor and is used to support a fan driving motor. The total and static pressure are applied to the restriction condition with the operating flowrate on the design point, and the efficiency is chosen as the response variable to be maximized. Through these procedures, an initial axial-fan blade designed by the free vortex method is modified to increase the efficiency with the satisfaction of the operating condition. The optimized fan is tested to compare the aerodynamic performance with an imported same class fan. The test result shows that the optimized fan operates with the satisfaction of restriction conditions, but the imported fan cannot. From the experimental and numerical test, they show that this optimization method improves the fan efficiency and operating pressures of a fan designed by the classical fan design method.

• KIPE Magazine
• /
• v.8 no.2
• /
• pp.36-42
• /
• 2003

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.4
• /
• pp.812-818
• /
• 2003

This paper presents a developed outside rotor type induction motor for the fan. Nearly all of the induction motors consist of two parts, rotor and stator, and the position of rotor is generally inside of stator. However, the rotor of the developed induction motor is located outside of stator. It is believed that the outside rotor type induction motor is suitable for the fan due to its large inertia, that is, it is considered that the change of air flow rate resulting from input power or load fluctuation is reduced. In this paper, the two tests which are suitable to obtain the electrical parameters of the outside rotor type induction motor were described, then various parameters of outside rotor type induction motor were measured. These are the locked rotor test and no load test. By using these tests, it was possible to determine the parameters which are presented in the steady-state equivalent-circuit of the outside rotor type induction motor. Load test of induction motor was carried out using a dynamometer and the torque-speed curve was obtained. It is believed that the results of this paper can be used for the development of the outside rotor type induction motor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.764-769
• /
• 2004

The DC Motor in a vehicle may cause noise and vibration because of high speed revolution, which can make a driver feel uncomfortable. There have been various studies attempting to solve these problems, focusing mostly on the causes of and ways to reduce noise and vibration. It is suggested that the noise in a DC Motor may be primarily due to interaction between a brush and a commutator. Brush noise, the most common noise in a DC Motor, results from a brush bounced from the surface of the commutator, fluctuation of the friction between the brush and the commutator, and the impact on the brush when passing over slots of the commutator. Based on the noise test, one of the most important design parameters was shown to be the roundness of the commutator. As the DC motor is used, the roundness of the commutator gets bigger with subsequent increase of the level of brush noise and vibration. There must be a threshold in order to prevent the brush noise from getting worse. Using the method of CAE is more efficient than the real test for purposes of looking for various design parameters to maintain the roundness of the commutator. In this study, the design process to reduce the brush noise is presented with the use of a computer model. The design parameters to reduce the brush noise and vibration are proposed by using FEM. The design parameters are used to reduce the noise and vibration of a DC motor and it is verified with the test results on a fan DC motor in a vehicle. This method may be applicable to various DC motors.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.4
• /
• pp.757-764
• /
• 2018

This paper describes the design and implementation of a 1hp class two-phase type BLDC fan motor used in an air conditioning system. The BLDC motor, which is implemented in this study, is not a commutator motor type with excellent lifetime and durability and is driven by two phase power source. The most important target specification of a motor used in an air conditioning system is that it has a high efficiency at the rated operating point. For this purpose, we designed the stator shape of the BLDC motor, the design of the rotor magnet, and the control circuit for driving. The BLDC motor has a structure where the motor part, the control part, and the power part are integrated. The finite element analysis was used to calculate the characteristics of the BLDC motors, and the conformity of the design results was confirmed by fabricating and testing the prototype model.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.10
• /
• pp.1281-1292
• /
• 2001

Experiments were done for the comparison of performance and flow characteristics between a two -stage axial flow fan and a counter-rotating axial flow fan. Each stage of the two -stage axial flow fan used fur the present study has an eight bladed rotor and thirteen slater blades. The front and the rear rotor of the counter - rotating axial flow fan have eight blades each and are driven by coaxial counter ro latins shafts through a gearbox located between the rear rotor and the electric motor. Both of the two axial fan configurations have identical rotor blades and the same operating condition fur the one -to-one comparison of the two. Performance curves of the two configurations were obtained and compared by varying the blade pitch angles and axial gaps between the blade rows. The fan characteristic curves were obtained following the Korean Standard Testing Methods for Turbo Fans and Blowers (KS B 6311). The fa n flow characteristics were measured using a five-hole probe by a non-nulling method. The velocity profiles between the hub and tip of the fans were measured and analyzed at the particular operating condition s of peak efficiency, minimum and maximum pressure coefficients. The peak efficiency of the counter-rotating axial fan was improved about 2% respectively, compared with the two stage axial fan. At the minimum pressure coefficient point of the two stage axial fan, the fan inlet flow patterns show that axial velocity highly decreased in the vicinity of the blade tip region. Also, the reverse flow took place at the blade tip.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.6
• /
• pp.849-859
• /
• 1998

The heat generated in an induction motor is mostly dissipated through the frame. The study on the heat transfer characteristics of a newly manufactured finless TEFC(Totally Enclosed Fan Cooled) induction motor showed/that it had an unsuitable structure in view of the heat transfer. The angle of the cooling air flow was very large and the ribs disturbed the air flow and partially generated the wake region on the frame. In the wake region the temperature was very high. Thus the heat transfer coefficients were lower than those of the frame with fins. Also was investigated the heat transfer characteristics of the motor frame by installing various guide vanes in the fan-side end cap. An optimum heat transfer case was found and the average heat transfer coefficient of the frame was 70% higher and the average coil temperature measured by the resistance method was 9 deg. C lower than that of the frame which had no guide vanes.