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

• The KSFM Journal of Fluid Machinery
• /
• v.11 no.5
• /
• pp.30-36
• /
• 2008

Axial fan without static blades requires the duct as a guidance for unskewed inflows. This work examined the geometric effects of a duct guided the in and out flows through an impeller. The present methodologies are computational predictions with parallel work by experimental validation. Several different positions of a rotor in a duct are proposed for plausible models of a rotor inside a duct. The optimum axial position of an impeller in a duct is found at the #4 model where the impeller lies on the inlet edge of a circular duct. The model shows a wider inlet area. The result of computational prediction is in good agreement with experiment measurement.

• Journal of Power System Engineering
• /
• v.17 no.3
• /
• pp.35-43
• /
• 2013

Generally, the chassis of an indoor RAC is composed of a rear-guider and a stabilizer. The aerodynamic performance of a cross-flow fan is strongly influenced by the various design factors of the chassis of an indoor RAC. The purpose of this paper is to select the optimum design factors through the aerodynamic performance of a cross-flow fan. The design factors are the leading angle of a rear-guider (${\theta}_1$), a stabilizer setup angle(${\theta}_2$), a rear-guider clearance(${\epsilon}_1$), and a stabilizer clearance(${\epsilon}_2$), respectively. As a result, the optimum design factors of an indoor RAC can be presented as a combination of ${\theta}_1=33^{\circ}$, ${\theta}_2=55^{\circ}$, ${\epsilon}_1=6{\sim}8mm$, and ${\epsilon}_2=7mm$ through the analysis of a static pressure coefficient and a static pressure efficiency.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.6
• /
• pp.761-768
• /
• 1999

This paper is studied to find the optimum condition of double-inlet Sirocco fan installed in an indoor PAC for low noise operation by the Taguchi method. The goal of this study is to obtain the best combination of each control factor which results in a desired flowrate of Sirocco fan with minimum variability. In this study, the parameter design of the Taguchi method is adopted for robust design by the dynamic characteristic analysis using orthogonal arrays and S/N ratios. The flowrate measurements are conducted by using a multiple-nozzle-type fan tester according to the orthogonal array L9($3^4$). The results of this study can be summarized as follows ; (i) The optimum condition of control factor is a set of where A is an inner to outer diameter ratio($D_1/D_2$), B is a width to outer diameter ratio($L/D_2$), C is a blade attachment angle(${\theta}$) and D is a number of blade(Z), (ii) The flowrate under the optimum condition satisfies the equation $y=0.0384{\cdot}M$ where M is a signal factor, namely number of revolution. The flowrate performance improves about 7.3% more largely as compared with the current condition, which results in about 35RPM reduction of number of revolution for the target flowrate $18.5m^3/min$, and (iii) The sensitivity analysis shows that the major factors in contribution to flowrate performance are A, B, and D ; the percentage contributions of each control factor are 44.01%(Z), 26.77%($D_1/D_2$) and 20.42%($L/D_2$).

• The Journal of the Acoustical Society of Korea
• /
• v.39 no.6
• /
• pp.515-523
• /
• 2020

This study aims to improve the flow and noise performances of an axial-flow fan for cooling the machine room in a refrigerator by using airfoil-cascade analysis and surface ridge shape. First, the experimental evaluations using a fan performance tester and an anechoic chamber are performed to analyze the flow and noise performances of the existing fan system. Then, the corresponding flow and noise performances are numerically assessed using the Computational Fluid Dynamics (CFD) techniques and the Ffowcs-Williams and Hawkings (FW-H) equation, and the validity of numerical results are confirmed through their comparisons with the experimental results. The analysis for the flow of a cascade of airfoils constructed from the existing fan blades is performed, and the pitch angles for the maximum lift-to-drag ratio are determined. The improved flow performance of the new fan applied with the optimum pitch angles is confirmed. Then, the fan blades with surface ridges on their pressure sides are devised, and the reduction of aerodynamic noise of the ridged fan is numerically confirmed. Finally, the prototype of the final fan model is manufactured, and improvements in the flow and noise performances of the prototype are experimentally confirmed.

• Fire Science and Engineering
• /
• v.23 no.5
• /
• pp.125-132
• /
• 2009

In this study we could contribute to the development of a precise checking tool with which the reliability of the automatic fire detection systems was enhanced and the safety of the people was ensured. In the same way as the domestic technical standard, the portable smoke sensitivity tester, which was developed in this work, could be used to check the capability of the smoke detectors installed in the field. Its heater inside was warmed up to $400^{\circ}C$ in 40 seconds and the paper as a smoke source was burned to produce smoke for the test. With the Photoelectric smoke detector it was possible to measure and control the smoke concentration in a range from 0%/m to 25%/m. With the adjustment of rpm of the fan, it was possible to keep a constant wind velocity in a range from 20cm/sec to 40cm/sec.

• The Journal of the Acoustical Society of Korea
• /
• v.42 no.1
• /
• pp.7-15
• /
• 2023

Recently, as interest in air quality in vehicles increases, the use of fine dust detection sensors for air quality measurement is becoming common. An axial-flow fan is inserted in the fine dust sensor installed in the air conditioning system in the vehicle to prevent dust from sinking directly on the sensor. When the sensor operates, the flow noise caused by the rotation of the axial-flow fan acts as a major noise source of the fine dust sensor. flow noise is recognized as one of the product competitiveness of fine dust sensors. In this study, the noise was gradually reduced at the same flow rate by improving the flow performance of the small axial flow fan. First, a virtual fan performance tester consisting of about 20 million grids was developed to analyze the aerodynamic performance of the target small axial-flow fan. In addition, the flow field was simulated by using compressible Large Eddy Simulation for direct computation of flow noise as well as high-accurate prediction of flow rate. The validity of numerical method are confirmed through the comparison of predicted results with experimental ones. After the effects of pitch angle on flow performance were analyzed using the verified numerical method, the pitch angle was determined to maximize the flow rate. It was found that the flow rate was increased by 8.1 % and noise was reduced by 0.8 dBA when the axial-flow fan with the optimum pitch angle was used.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.1167-1171
• /
• 2008

The flow and thermal performance of the skiving and louver fin type heat sinks for the cooling system of the small LED projector were experimentally evaluated. A small fan tester based on AMCA standards was used to control and measure the air flow rate into the heat sink. Three heat blocks were used to simulate the heat and light sources(red, green and blue) of the small LED projector. We measured the pressure drop, temperatures and input power at the specific air flow rate and discussed those results. As a result, it is found that the louver fin type heat sink has higher pressure drop and lower thermal resistance than the skiving type. From the comparison of the temperature of the heat block between skiving and louver fin type, the louver fin type heat sink was found to be more suitable for cooling the high power heat source than skiving type. The thermal performance of the fan-sink(louver fin type) system was discussed with the picture taken by a thermal video.

• The Journal of the Acoustical Society of Korea
• /
• v.36 no.6
• /
• pp.371-377
• /
• 2017

The performance of an air conditioner is closely related to the cooling performance of a split-type outdoor unit so that, in most of the relevant preceding studies, the independent performance of an axial fan in an outdoor unit has been studied. However, there is a lack of research on the effects of other components in an outdoor units was rarely investigated. Therefore, in this paper, the effects of the fan orifice among other parts on the flow performance of the outdoor unit was numerically investigated. A virtual fan tester consisting of 18 million grids was developed for highly resolved flow simulation. The unsteady RANS (Reynolds-averaged Navier-Stokes) equations are numerically solved by using finite-volume CFD (Computational Fluid Dynamics) techniques. In order to verify the validity of the numerical methods, the predicted P-Q curve of the cooling fan in a full outdoor unit is compared with the measured one. Optimization of orifice shape was carried out for maximum flow performance of the outdoor unit using the validated numerical method.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.2
• /
• pp.117-124
• /
• 2018

This paper describes the localization development of an axial fan for KM-SAM multi-function radar. The multi-function radar, which is constantly affected by the external environment, is a key instrument for detecting and tracking low and medium altitude threat targets. Operating this equipment smoothly requires a fan for controlling the internal temperature and humidity. Presently, all such fans are imported. To solve these problems, localization development research was proposed. The development of localization includes analysis of requirements through review of related technical reports such as original equipment and system equipment specification, prototype design, and verification of design requirement through performance test and environmental test. The study results are described. The blower consisted of an axial fan with guide vanes and the motor was designed to generate a maximum airflow of 970 CFM and a wind pressure of 4.8 IWG. Six prototypes were manufactured for performance evaluation. In addition, for reliable data acquisition, AC power supply, fan performance tester and data acquisition equipment were designed and tested. All prototypes were verified as having design requirements equal to or better than those of imports.