• The KSFM Journal of Fluid Machinery
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• v.13 no.3
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• pp.24-29
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• 2010

Axial fans for an air-conditioning unit are designed to equip the system with an expected flow-rate and low noise level by applying the blade design method of multi-sectioning and local camber generation. In this study, the distributions of chord length, stagger angle, and camber angle are globally and locally determined for the given specific speed, which is considered to be relatively high. The mock-up fans are observed to satisfy the aerodynamic performance and the noise level for the system simultaneously and discussed in terms of local flow patterns related to the emitted noise.

• Journal of computational fluids engineering
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• v.16 no.3
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• pp.75-81
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• 2011

The turbo blowers having large power capacity are generally composed of the variable inlet guide vane, the impeller and the variable diffuser. In the present study, the effect of the stagger angles on the aerodynamic performances has been investigated by CFD methods. The design specifications of the reference model having 400kW power were given as 7.43kg/s of mass flow rate, 1.66 of pressure ratio with 12000rpm of impeller rotating speed. As the first simulation parameter, the diffuser vane angle was varied in the range of ${\pm}$20 degree from the initial-design point. The inlet guide vane angles, as the second one, was changed in the range of ${\pm}$40 degree from the initial-design point. The commercial Navier-Stokes solver, ANSYS-CFX, was applied to solve the three-dimensional unsteady flow fields inside the turbo blower. Through the numerical results, the desirable setting angles were proposed to fit the best performance to the variation of the operating conditions.

• The KSFM Journal of Fluid Machinery
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• v.3 no.2 s.7
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• pp.36-43
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• 2000

This study presents the centrifugal compressor performance for three different vane stagger angles and wall pressure distribution within vaned diffuser channels, and is also discussed about the stability with respect to the compressor components. As the vane stagger angle decreases, the flow rate for the stall onset decreases, and higher pressure can be obtained at the low flow rate region, however, the effective operation range of the compressor decreases because of the blockage effect of the diffuser vane. Low pressure pocket within the vaned diffuser channel moves from the pressure side of leading edge to the suction side as the flow rate decreases. The compressor system stability mainly depends on that of the diffuser.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.652-657
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• 2002

It is addressed that the turbulent broadband sound power from a sirocco fan can be modeled by the trailing edge noise. The trailing edge noise is usually influenced by inflow turbulence, separation and boundary layer on the blade. The design parameters such as solidity(c/s) and stagger angle are specified to predict performance and noise level because the separation and slip velocity are strongly affected by them along with the flow coefficient. This paper reports the effects of the stagger angle upon the trailing edge noise for various trailing edge shapes. It is believed that the serrated trailing edge provides break-up mechanism for organized convecting vortices, thereby reduce the overall noise level.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.396-401
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• 2000

It is addressed that the turbulent broadband sound power from a sirocco fan can be modeled by the trailing edge noise. The trailing edge noise is usually influenced by inflow turbulence, separation, and boundary layer on the blade. The design parameters such as solidity(c/s) and stagger angle are specified to predict performance and noise level because the separation and slip velocity are strongly affected by them along with the flow coefficient. This paper reports the effects of the solidity and the stagger angle upon the trailing edge noise from the circular arc-shaped blade of sirocco fan.

• New & Renewable Energy
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• v.20 no.1
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• pp.116-125
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• 2024

Ultra-low-head is an unexplored classification among the sites in which hydroelectric power can be produced. This is typically owing to the low power output and the economic value of the turbines available in this segment. A turbine capable of operating in an ultra-low-head condition without the need of a dam to produce electricity is developed in this study. A gate structure installed at a shallow water channel acting as a weir generates artificial head for the turbine mounted on the gate to produce power. The turbine and generator are designed to be compact and submersible for an efficient and silent operation. The gate angle is adjustable to operate the turbine at varying flow rates. The turbine is designed and tested using computational fluid dynamics tools prior to manufacturing and experimental studies. A parametric study of the runner blade parameters is conducted to obtain the most efficient blade design with minimal hydraulic losses. These parameters include the runner stagger and runner leading edge flow angles. The selected runner design showed improved hydraulic characteristics of the turbine to operate in an ultra-low-head site with minimal losses.

• The KSFM Journal of Fluid Machinery
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• v.11 no.6
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• pp.7-17
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• 2008

Fan performances are obtained with various tip clearance gaps and stagger angles of the rotor. A tested fan is an axial-type fan of which the casing diameter is 806 mm. Two different rotors are applied to this test. One is designed on the basis of the free vortex method along the radial direction and the other is designed using the forced vortex method. The operating conditions are varied to the ultimate off-design point as well as the deign point. Overall efficiency, total pressure and input power are compared with the tip clearance gaps and different stagger angle. The experimental results show that changing of the stagger angle has minor influence to the performance when the same rotor is applied. When the tip clearance gap is less than 5% of the rotor span, the overall efficiency, total pressure loss and input power reduction are varied linearly with the variation of the tip clearance gaps. On the design point, the overall efficiency is decreased to the rate of 2.8-2.9 to the increasing of the tip clearance, but the changing rate of the overall efficiency is alleviated when the fan operates at off-design points. In particular, this rate is more quickly declined on a fan with the rotor designed using the forced vortex method. The result of the total pressure shows that the pressure reduction rate is a 0.08-0.1 according to the tip clearance, and additionally the input power reduction rate is a 0.045-0.065 at design point.

• Journal of Power System Engineering
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• v.16 no.5
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• pp.55-62
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• 2012

Centrifugal compressors are widely used and each operating condition is different. However, it cannot be manufactured according to the every operating condition. In the this study, performance of compressor was evaluated with various rotational speeds of impeller and various stagger angles of diffuser in order to apply a typical model widely. A centrifugal compressor was designed and manufactured based on the design point. On this machines, an experiment was conducted and the performance was predicted at off-design point. The performance prediction was validated with the experimental result and the numerical result. Although the isentropic efficiency on the prediction was slightly lower than that on the experimental result due to the heat loss in the experiment, the pressure ratio was predicted well and also the predicted results were matched well with the numerical results. When the rotational speed of the impeller and the stagger angle of the diffuser were changed together, the compressor can be worked in the high efficiency region and avoided operating in the stall region.

• 한국전산유체공학회:학술대회논문집
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• 2000.05a
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• pp.73-77
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• 2000

Small-sized fans for cooling electronic components are usually produced by injection molding in unified form including blade and hub. However, in case of middle and large-sized fans, they deal ill various products with varied numbers of blade or stagger angles after designing a single blade by molding or aluminum die casting. At this occasion, it is necessary to study design method for high-performance axial fans can be operated with various numbers of blades or stagger angle using unique blade for specified conditions. Therefore, the goal in this study is developing a optimal design method which improves performance of axial fans within the large range of operating by single blade.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.137-142
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• 2000

The turbulent broadband sound power from a forward curved bladed fan can be modeled by the trailing edge noise. The trailing edge noise is usually influenced by inflow turbulence, separation, and boundary layer on the blade. This paper reports the effects of the solidity (C/s) and the stagger angles upon the trailing edge noise with respect to the trailing edge shapes of circular-arc cambered blade of multi-bladed fan, and discusses the major physical mechanism of reduced noise lot the circular trailing-edged case.