• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.2
• /
• pp.11-21
• /
• 2005

A three-dimensional parallel Euler flow solver has been developed for the simulation of unsteady rotor-fuselage interaction aerodynamics on unstructured meshes. In order to handle the relative motion between the rotor and the fuselage, the flow field was divided into two zones, a moving zone rotating with the blades and a stationary zone containing the fuselage. A sliding mesh algorithm was developed for the convection of the flow variables across the cutting boundary between the two zones. A quasi-unsteady mesh adaptation technique was adopted to enhance the spatial accuracy of the solution and to better resolve the wake. A low Mach number pre-conditioning method was implemented to relieve the numerical difficulty associated with the low-speed forward flight. Validations were made by simulating the flows around the Georgia Tech configuration and the ROBIN fuselage. It was shown that the present method is efficient and robust for the prediction of complicated unsteady rotor-fuselage aerodynamic interaction phenomena.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.8
• /
• pp.1077-1087
• /
• 2002

The heat (mass) transfer characteristics on the blade surface of a high-turning first-stage turbine rotor for power generation has been investigated by employing the naphthalene sublimation technique. A four-axis profile measurement system is developed successfully for the measurements of local sublimation depth on the curved surface In the leading edge region, there is a good agreement between the present heat (mass) transfer data and the previous result on a turbine blade with a moderate turning angle, but some discrepancies are found in the mid-chord heat (mass) transfer between the two results. The local heat (mass) transfer on the present suction surface is greatly enhanced due to an earlier boundary transition, compared with that on a turbine blade with a moderate turning angle, meanwhile there is only a slight change in the pressure-side heat (mass) transfer between the two different turbine rotors. In general, the heat (mass) transfer augmentation by the endwall vortices is found much higher on the suction surface than on the pressure surface.

• Journal of computational fluids engineering
• /
• v.17 no.2
• /
• pp.1-10
• /
• 2012

This paper presents the numerical simulation results of heat transfer and friction loss for a rotating two-pass duct with the airfoil-guide vanes in the turning region. The Kriging model is used as an optimization technique with Reynolds-averaged Navier-Stokes analysis of flow field and heat transfer with shear stress transport turbulent model. To improve the heat transfer performance, angle and location of the airfoil-guide vanes have been selected as design variables. The optimization problem has been defined as a minimization of the objective function, which is defined as a linear combination of heat transfer related term and friction loss related term with a weight factor. The airfoil-guide vanes in the turning region keep the high level of heat transfer while the friction loss has a low value. By comparing the presence or absence of airfoil-guide vanes, it is shown that the airfoil-guide vanes exhibited the best heat transfer performance to improve the blade cooling except the first passage.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.842-849
• /
• 2011

Open Rotor Engine is one of the several new technologies offering potential solution for the next generation aircraft. The coupling of ultra high bypass ratio and aerodynamically advanced fan blade design allow the open rotor engine to achieve and advantage in fuel consumption. The open rotor engine does have more thrust lapse than the general high bypass turbofan. The open rotor engine performance model was analyzed using a reference data based on the GE36 which was designed and tested data at which time a F404 turbojet was used as the core. The performance model of open rotor engine was verified by referred test data and was evaluated to be properly constructed, through the comparison of recent Next generation turboprop engine performance.

• The KSFM Journal of Fluid Machinery
• /
• v.6 no.3 s.20
• /
• pp.21-27
• /
• 2003

Dispersion of coolant jets in a film cooling flow field is the result of a highly complex interaction between the film cooling jets and the mainstream. In order to investigate the effect of blowing ratios on the film cooling of a turbine blade, cylindrical body model is used. Mainstream Reynolds number based on the cylinder diameter is $7.1{\times}10^4$. The effects of coolant flow rates are studied for blowing ratios of 0.7, 1.0, 1.3 and 1.7, respectively. The temperature distribution of the cylindrical model surface is visualized with infrared thermography (IRT). Results show that the film cooling performance could be significantly improved by the shaped injection holes. For higher blowing ratio, the spanwise-diffused injection holes are better due to the lower momentum flux away from the wall plane at the hole exit.

• 연구논문집
• /
• s.27
• /
• pp.127-139
• /
• 1997

Two-for-one twister is a kind of textile machine and makes special fancy yarn which is twisted two times per one revolution in order to increase tensile strength and wear resis-tance of yarn. Spindle mechanism has to be stable and continuous motion in high speed revolution, and then optimal design is necessary to analyze dynamic characteristics of spindle unit. Spindle unit is consist of blade and rotary disc that are cylindrical body of revolution. For analysis of the dynamic characteristics of spindle unit, transfer matrix method is used and a numerical code SPINDLE also. Torsion and natural bending frequency of the spindle unit are examined. Its displacement mode is studied in function of variable revolutions.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.7
• /
• pp.933-943
• /
• 2001

Using a semi-circled blunt body model, the geometrical effects of injection hole on the turbine blade leading edge film cooling are investigated. The film cooling characteristics of two shaped holes (laterally- and streamwise-diffused holes) and three cylindrical holes with different lateral injection angles, 30°, 45°, 60°, respectively, are compared with those of cylindrical hole with no lateral injection angle experimentally and numerically. Kidney vortices, which decrease the adiabatic film cooling effectiveness, appear on downstream of the cylindrical hole with no lateral injection angle. At downstream of the two shaped holes have better film cooling characteristics than the cylindrical one. Instead of kidney vortices, single vortex appears on downstream of injection holes with lateral injection angle. The adiabatic film cooling effectiveness is symmetrically distributed along the lateral direction downstream of the cylindrical hole with no lateral injection angle. But, at downstream of the cylindrical holes with lateral injection angle, the distribution of adiabatic film cooling effectiveness in the lateral direction shows asymmetric nature and high adiabatic film cooling effectiveness regions are more widely distributed than those of the cylindrical hole with no lateral injection angle. As the blowing ratio increases, also, the effects of hole shapes and injection angles increase.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.6
• /
• pp.827-833
• /
• 2008

In this study, mathematical expressions based upon the conventional BEMT(blade element momentum theory) was applied to basic 100kW wind turbine blade configuration design. Power coefficient and related flow parameters, such as Prandtl's tip loss coefficient, tangential and axial flow induction factors of the wind turbine were analyzed systematically. X-FOIL was used to acquire lift and drag coefficients of the 2-D airfoils and Viterna-Corrigan formula was used o interpolate he aerodynamic characteristics in post-stall region. Also, aerodynamic characteristics, measured in a wind tunnel to calculate he power coefficient was applied. The comparative results such as axial and tangential flow factors, power coefficients were presented in this study. Power coefficient, calculated by in-house code was compared with the GH-Bladed result. The difference of the aerodynamic characteristics caused the difference of the performance characteristics as variation as TSR.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.26 no.3
• /
• pp.384-393
• /
• 2002

The effects of hole expansion angle and the arrangement of nozzles on a film cooling system for a turbine-blade-shaped surface were experimentally investigated. Liquid crystal with flue-temperature correlation and an image processing system were employed to evaluate surface temperature. Distributions of cooling effectiveness were then presented to figure out the change of heat transfer characteristics with different geometric conditions of cooling-holes. It was found thats the averaged cooling efficiency on the suction surface was maximum with 10 degree of the cooling hole expansion angle. It was also shown that the averaged cooling efficiency on the pressure surface and the averaged cooling efficiency for dual array case were not affected by the hole expansion angle.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.14 no.1
• /
• pp.39-47
• /
• 2006

Recent trend in pursuit of high performance and effectiveness for automotive cooling system has changed the application of material for impeller of automotive water pump from metal to high ability engineering resin, which can achieve optimization of design of impeller geometry and realize lightweight high efficiency water pump. Closed type water pump improves hydraulic loss of fluid through the clearance between volute casing and impeller compared with that of the existing open type water pump(Although closed type is heavier than open type for the same size and same material, adoption of plastics can solve the problem.). In the present study, the characteristics of hydraulic performance of closed type water pump were investigated with respect to the angle between shroud and hub of impeller and the shape of discharge port of volute casing. Performance tests were carried out for 4 cases, that is, for 2 impellers and 2 casings. The modification of shape of only discharge port can enhance the hydraulic performance by 10 percent and the pump efficiency by 4-6 percent.