• Journal of the Korea Convergence Society
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• v.11 no.3
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• pp.195-200
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• 2020

In this study, the flow analyses were performed on the fluid clutch turbine blade shapes of models 1, 2 and 3, with eight turbine blades tilted at 45 °, 40 °, and 35 ° angles on the propulsion shaft, respectively. The larger the angle of inclination on the propulsion shaft, the higher the flow pressure among the flow models after the back of the turbine blades. On the other hand, the smaller the angle of inclination on the propulsion shaft of the turbine wing, the lower the flow rate. It can be seen that the smaller inclination angle of the turbine blade surface on the propulsion shaft, i.e., the wing shape close to perpendicular to the flow of fluid, is more suitable for efficiently connecting and disconnecting the fluid clutch. By applying the flow analysis by type of turbine blade of fluid clutch,the study result at this paper is considered to be favorable as the convergent research material which can apply the aesthetic design.

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

• 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.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.303-308
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• 2001

A rotating blade of steam turbines is designed using blade design system. To minimize the design time. quasi three dimensional flow analysis code is adopted to calculate blade section. The blade section lies on a streamline determined by previous steam turbine design procedures. The blade design system makes a transform of streamline coordinates, (m, r$\theta$), to (m', $\theta$) coordinates and all design procedure except 3 dimensional stack-up is performed in the coordinates. Each designed blade section is stacked-up and whole 3 dimensional blade can be modified by correcting 2D section, repeatly. The full 3D numerial analysis for the one stage including designed rotating blade will be performed later

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.5
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• pp.847-852
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• 2004

The wind turbine blade is the equipment converted wind into electric energy. The effect of the blade has influence of the output power and efficiency of wind turbine. The design of blade is considered of lift-to-drag ratio. structure. a condition of process of manufacture and stable maximum lift coefficient, etc. This study is used the simplified method for design of the aerodynamic blade and aerodynamic analysis used blade element method This Process is programed by delphi-language. The Program has any input values such as tip speed ratio blade length. hub length. a section of shape and max lift-to-drag ratio. The Program displays chord length and twist angle by input value and analyzes performance of the blade.

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.4
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• pp.273-279
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• 2011

Turbulent flow analysis around a wind turbine blade was performed to evaluate the power performance of offshore wind turbine. Fluent package was utilized to solve the Reynolds-averaged Navier-Stokes equations in non-inertial rotating coordinates. The realizable k-$\varepsilon$ model was used for turbulence closure and the grid system combining structured and unstructured grids was generated. In the first, lift and drag forces of 2-D foil section were calculated and compared with existing experimental data for the validation. Then torque and thrust of the wind turbine blade having NACA 4-series sections were calculated with fixed pitch angle and rpm. Tip speed ratio was varied by changing wind speed. In the next, three kinds of end plate were attached at the tip of blade in order to increase the power of the wind turbine. Among them the end plate attached at the suction side of the blade was found to be most effective. Furthermore, performance analysis with tilt angle and rake was also performed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.1
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• pp.1580-1597
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• 1969

1. The field test of our experiment comparing the traditional syckle and the new manually pulled cutter showed that the working efficiency of the manually pulled cutter is about two times higher than that of the syckle. The operator can standerect while using the manually pulled cutter, thus reducing fatigue. Because of the reduction in body fatigue, the operator is able to work more total hours, making the manually pulled harvester three times more efficient than the syckle. 2. The optimum angle for the V-shaped cutter blade varies according to the number of the hiller, but in manufacturing the cutter, the range must be controlled between $35^{\circ}{\sim}45^{\circ}$. 3. The radius of curvature of the V-shaped blade is closely related to the blade angle. The best results were obtained when the radii of curvature were r=32cm with $35^{\circ}$ angle, r=153mm with $45^{\circ}$ angle, and r=220mm with $40^{\circ}$ angle. 4. The hardness distribution test of the blade showed great differences between foreign made and domestic made blades. The heat treatment method must be greatly improved for superior hardness distribution. 5. Although the efficiency of the manually pushed cutter is equal to that of the manually pulled cutter, the manually pushed cutter is not only more expensive to produce but also has a much more complicated structure than the manually pulled cutter. Because of our rural economic conditions, the power harvester which is utilized in foreign countries can not yet be introduced here. Thus, the manually pulled cutter should be popularized in our rural areas until economic conditions will allow us to introduce power harvesters. 6. The use of the manually pulled cutter will make it possible for an operator to harvest an area in only one-third of the time that it would take to harvest the same area with a traditional syckle, and it will make it possible for an operator to earn about 8,000 won for harvesting 10 Jung-bo: such benefits will help in increasing farm income and will contribute to farm modernization.

• Wind and Structures
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• v.33 no.6
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• pp.471-480
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• 2021

This present paper leads to investigation of blade-fluid interactions of cambered blade H-Darrieus rotor having EN0005 airfoil blades using comprehensive Computational Fluid Dynamics (CFD) analysis to understand its performance in low wind streams. For several blade azimuthal angle positions, the effects of three different low wind speeds are studied regarding their influence on the blade-fluid interactions of the EN0005 blade rotor. In the prevailing studies by various researchers, such CFD analysis of H-Darrieus rotors are very less, hence it is needed to improve their steady-state performance in low wind velocities. Such a study is also important to obtain important performance insights of such thin cambered blade rotor in its complete rotational cycle. It has been seen that the vortex generated at the suction side of the EN0005 blade rolls back to its leading edge due to the camber of the blade and thus a peak velocity occurs near to the nose position of this blade at its leading edge, which leads to peak performance of this rotor. Again, in the returning phase of the blade, a secondary recirculating vortex is generated that acts on the pressure side of EN0005 blade rotor that increases the performance of this cambered EN0005 blade rotor in its downstream position as well. Here, the aerodynamic performances have been compared considering Standard k-ε and SST k-ω models to check the better suited turbulence model for the cambered EN0005 blade H-Darrieus rotor in low tip speed ratios.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.2
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• pp.24-31
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• 2001

An axial-type turbine design technology is developed. In order to design one-stage turbine, the preliminary design method is applied, and then design parameters are chosen after analyzing gas properties within the turbine passage using the streamline curvature method. Stator blade is designed using C4 profile, and rotor blade is designed using shape parameters. Stator is manufactured as an integral type and rotor is manufactured to be disassembled from the disc for changing blade incidence angle. The output power from the rotor is measured with various RPM and input power. Experimental results show that the maximum efficiency of turbine rotor is obtained on the design point, and the output power is proportionally decreased with the negative incidence angle even the test turbine is a reaction turbine. The efficiency of turbine rotor is decreased to 5% by $7.5^{\cire}$ negative incidence angle from the designed value.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.2
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• pp.212-224
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• 2018

The characteristics of the relationship between the evolution of propeller trailing vortex wake and skew angle are numerically examined based on four different five-blade David Taylor Model Basin (DTMB) model propellers with different skew angles. Numerical simulations are based on Reynolds-averaged Naviere-Stokes (RANS) equations combined with SST $k-{\omega}$ turbulence model. Results show that the contraction of propeller trailing vortex wake can be restrained by increasing skew angle and loading conditions, and root vortices fade away when the propeller skew angle increases. With the increase of the propeller's skew angle, the deformation of the hub vortex and destabilization of the tip vortices are weakening gradually because the blade-to-blade interaction becomes weaker. The transition trailing vortex wake from stability to instability is restrained when the skew increases. Furthermore, analyses of tip vortice trajectories show that the increasing skew can reduce the difference in trailing vortex wake contraction under different loading conditions.