• International Journal of Fluid Machinery and Systems
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• v.5 no.4
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• pp.161-167
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• 2012

Small-sized axial fans are used as air coolers for electric equipment. There is a strong demand for higher power of fans according to the increase of quantity of heat from electric devices. Therefore, higher rotational speed design is conducted, although, it causes the deterioration of the efficiency and the increase of noise. Then, the adoption of contra-rotating rotors for small-sized fans is proposed for the improvement of the performance. In the case of contra-rotating rotors, blade row distance between the front and the rear rotors influences on the performance and the noise. Therefore, it is important to clarify the optimum blade row distance between front and rear rotors. The performance curves of the contra-rotating small-sized axial fan under the condition of different blade row distances are shown and the blade row interaction between the front and the rear rotors are discussed by the numerical results. Furthermore, the optimum blade row distance of the contra-rotating small-sized axial fan is considered.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.36-41
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• 2001

In order to simulate wake of stator and a gas turbine engine's balde row, acryl cylinder and a linear turbine cascade were used respectively in this study. Experimental of heat transfer distributions was done on the passage endwall and blade suction surface. Temperature distributions on the experimental regions were obtained through image processing system by using the cholesteric type liquid crystal which has chain structure of metyl$(CH_3)$. To represent the degree of heat transfer, dimensionless St number was used. The results show that heat transfer on the blade suction surface was increased due to the wake from the cylinder and was decreased as the distance between cylinder row and blade row increases. Because of groth of passage vortex, heat transfer distributions on the trailing edge area showed triangular shape which was little changed with wake. On the other hand, heat transfer on the passage endwall was decreased due to the wake from cylinder. As the distance between cylinder row and blade row increases, heat transfer was more decreased.

• The KSFM Journal of Fluid Machinery
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• v.17 no.3
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• pp.59-64
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• 2014

The kidney vortex is the important factor adversely influencing film cooling effectiveness. In general, double jet film-cooling hole is designed to overcome the kidney vortex by generating anti-kidney vortices. In this study, the film cooling characteristics and the effectiveness of the double jet film cooling hole were numerically investigated with various area ratios of the first($A_1$) and second($A_2$) cooling hole($A_1/A_2$=0.8, 1.0, 1.25) and lateral ejection angle(${\alpha}$ = $30^{\circ}$, $45^{\circ}$, $60^{\circ}$) as the design parameters. The effects of lateral distance between the first and second row holes are investigated. Numerical study was performed by using ANSYS CFX with the shear stress transport(SST) turbulence model. The film cooling effectiveness and temperature distribution were graphically depicted with various flow and geometrical conditions.