• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.8
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• pp.2707-2720
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• 1996

The aerodynamic design of the two-stages of centrifugal compressors in an 1.2MW industrial gas turbine is completed with the application of numerical analyses. The final shape of an intake, the axial guide vanes and a return channel is determined using several interactions between design and two-dimensional turbulent flow analysis, focused on the minimum loss of internal flows. The one-dimensional turbulent flow analysis, focused on the minimum loss of internal flows. The one-dimensional design and prediction of aerodynamic performances for the compressors are performed by two different methods; one is a method with conventional loss models, and the other a method with the two-zone model. The combination methods of the Betzier curves generate three-dimensional geometric shapes of impeller blades which are to be checked with a careful change of aerodynamic blade loadings. The impeller design is finally completed by the applications of three-dimensional compressible turbulent flow solvers, and the effect of minor change of design of the second-stage channel diffuser is also studied. All the aerodynamic design results are soon to the verified by component performance tests of prototype centrifugal compressors.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.444-447
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• 2009

The optimum design and the performance analysis software called POSEIDON for the HAWT (Horizontal Axis Wind Turbine) was developed by use of BEMT. The Prandtl's tip loss theory was adopted to consider the blade tip loss. The aerodynamic characteristics of NACA 63415 airfoils were predicted via X-FOIL and the post stall characteristics were estimated by the Viterna's equations. All the predicted aerodynamic characteristics are fairly well agreed with the Velux wind tunnel test results. The rated power of the testing rotor is 5kW at design conditions. The power, estimated by use of predicted lift and drag coefficient via X-FOIL becomes a little higher than experimental one.

• Journal of Power System Engineering
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• v.3 no.3
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• pp.54-59
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• 1999

The purpose of the present study was to develop the numerical method for predicting the on-design and off-design performance of multistage axial-flow compressors. The aerodynamic properties in blade rows were analyzed by incorporating the streamline curvature method as a quasi 3D analysis with the imperical modeling of exit flow angle and loss coefficients. The present calculation procedure has been tested by applying to 5-stage compressors and good agreement with experiments has been found. The detail analysis of aerodynamic performances has been done on the compression part of the bench-scaled gas turbine engines. The predicted performance map at the variable speedline and flow rates could be used as a guide of the engine operation.

• Journal of computational fluids engineering
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• v.18 no.1
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• pp.91-97
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• 2013

In the present study, the effects of contaminant accumulation and surface roughness on the aerodynamic performance of wind turbine blade sections were numerically investigated by using a flow solver based on unstructured meshes. The turbulent flow over the rough surface was modeled by a modified ${\kappa}-{\omega}$ SST turbulence model. The calculations were made for the NREL S809 airfoil with varying contaminant sizes and positions at several angles of attack. It was found that as the contaminant size increases, the degradation of the airfoil performance becomes more significant, and this trend is further amplified near the stall condition. When the contaminant is located at the upper surface near the leading edge, the loss in the aerodynamic performance of the blade section becomes more critical. It was also found that the surface roughness leads to a significant reduction of lift, in addition to increased drag.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.61.2-61.2
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• 2011

The spanwise aerodynamic loads of the wind turbine blade are investigated numerically. The blade shape such as twist and chord length along the blade span is obtained from the procedure of aerodynamically optimal design. The rated tip speed ratio and the rated wind velocity are set to 7 and 12m/s respectively. The BEM method is applied to obtain both the aerodynamic performance of the wind turbine (Fig.1) and the spanwise aerodynamic loads along the blade span including Prandtl's tip loss factor. The maximum running power coefficient is occurred around 90% radial position from hub (Fig.2). The distributed aerodynamic loads along the blade span can be used for structure analysis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.9
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• pp.1255-1266
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• 1998

Effects of a length-to-diameter ratio, L/D, on the three-dimensional flow and aerodynamic loss within an injection hole, which is normally oriented to the mainflow, have been investigated by using a straight five-hole probe. The length-to-diameter ratio of the injection hole is varied to be 0.5 and 2.0 for blowing ratios of 0.5, 1.0 and 2.0. Regardless of the blowing ratio, flows within the hole and at the jet exit are strongly affected by the length-to-diameter ratio. In the case of L/D=0.5, the inside flow is considerably influenced by the mainflow, and the exit flow variation is found to be the greatest. The aerodynamic loss in this case is usually attributed to jet -mainflow interactions. In the case of L/D=2.0, the flow separation and reattachment in the inlet region are completely separated from the complicated exit flow, and the aerodynamic-loss production is mainly due to the inlet flow separation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.399-406
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• 2014

Three-dimensional flow and aerodynamic loss in the tip-leakage flow region of a turbine blade equipped with both a pressure-side winglet and a suction-side squealer have been measured for the tip gap-to-span ratio of h/s = 1.36%. The suction-side squealer has a fixed height-to-span ratio of $h_s/s$ = 3.75% and the pressure-side winglet has width-to-pitch ratios of w/p = 2.64%, 5.28%, 7.92% and 10.55%. The results are compared with those for a plane tip and for a cavity squealer tip of $h_{ps}/s$ = 3.75%. The present tip delivers lower loss in the passage vortex region but higher loss in the tip-leakage vortex region, compared to the plane tip. With increasing w/p, its mass-averaged loss tends to be reduced. Regardless of w/p, the present tip provides lower loss than the plane tip but higher loss than the cavity squealer tip.

• The KSFM Journal of Fluid Machinery
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• v.2 no.4 s.5
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• pp.57-64
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• 1999

The prediction method of the performance and aerodynamic noise from a sirocco fan was developed and compared with measured data. To predict the performance of the sirocco fan, the well-known slip coefficients and various loss models were tested and applied to forward curved sirocco impellers. Using loss models proposed for both impeller and casing, the predicted performance characteristics were in good agreement with measured ones by an ANSI test plenum. Various scaling models for aerodynamic noise from the sirocco fan were evaluated and tested against measured power levels in terms of flow coefficient. It was shown that the turbulent broadband sound power from the sirocco fan can be modeled successfully by trailing edge noise.

• 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.

• The KSFM Journal of Fluid Machinery
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• v.13 no.2
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• pp.59-64
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• 2010

A design method of Sirocco fan is developed for constructing 3-D impeller and scroll geometries, and for predicting both the aerodynamic performance and the noise characteristics of the designed fan. The aerodynamic blading design of fan is conducted by blade angle, camber line determinations and airfoil thickness distribution, and then the scroll geometry of fan is designed by using logarithmic spiral. The aerodynamic performance of designed fan is predicted by the meanline analysis with flow blockage, slip and pressure loss correlations. Based on the predicted performance data, fan noise is predicted by two models for cutoff frequency and broadband noise sources. The present predictions for the performance and the noise level of actual fans are well agreed with measurement results.