• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.39-49
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• 2010

In this paper, a numerical study has been carried out to investigate the influence of jet fan design variables on the performance of a jet fan. In order to achieve an optimum jet fan design and to explain the interactions between the different geometric configurations in the jet fan, three-dimensional computational fluid dynamics and the DOE method have been applied. Several geometric variables, i.e., hub-tip ratio, meridional shape, rotor stagger angle, number of rotor-stator blades and stator geometry, were employed to improve the performance of the jet fan. The objective functions are defined as the exit velocity and total efficiency at the operating condition. Based on the results of computational analyses, the performance of the jet fan was significantly improved. The performance degradations when the jet fan is operated in the reverse direction are also discussed.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.396-401
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• 2004

In this paper, a 1MW HAWT(FIL-1000) rotor blade has been designed by BEMT(Blade Element Momentum Theory) with Prandtl's tip loss. Also, a 3-D flow and performance analysis on the FIL-1000 rotor blade has been carried out by using the 3-D Navier-Stokes commercial solver (CFX-5.7) to provide more efficient design techniques to the large-scale HAWT engineers. The rated power and itsapproaching wind velocity at design point (TSR=7.5) are 1MW and 9.99m/s respectively. The rotor diameter is 54.5m and the rotating speed is 26.28rpm. Airfoils such as FFA W-301, DU91-W-250, DU93-W-210, NACA 63418, NACA 63415 consist of the rotor blade from hub to tip. Recent CFX version, 5.7 was adopted to simulate 3-D flow field and to analyze the performance characteristics of the rotor blade. Entire mesh node number is about 730,000 and it is generated by ICEM-CFD to achieve better mesh quality The predicted maximum power occurringat the design tip speed ratio is 931.45kW. Approaching to the root, the inflow angle becomes large, which causesthe blade to be stalled in the region. Therefore, k-$\omega$ SST turbulence model was used to predict the quantitative flow information more accurately. Application of commercial CFD code to optimum blade design and performance analysis was proved to be more effective environment to HAWT blade designers.

• The KSFM Journal of Fluid Machinery
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• v.10 no.3 s.42
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• pp.17-24
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• 2007

This paper presents the design procedure of a vertical wind turbine named jet-wheel-turbo turbine and the numerical and experimental verifications. The design parameters such as the rotor inlet angle, the diameter-to-hub ratio, the inlet guide outlet angle and the solidity were optimized to maximize the energy transfer, and to further increase the turbine efficiency by applying the side guide vane and the side opening to the rotor. The maximum power coefficient of 0.59, which is much higher than the ever-designed three-bladed horizontal turbines, was experimentally obtained when the optimal inlet- and side-guide vanes were installed and both sides of the rotor were 80% opened. The maximum power coefficients occur at the tip speed ratio ranging between 0.6 and 0.7. This vertical-axis turbine model can be applied to the large-scale power generation system with the speed and torque control algorithm for the specified wind characteristics.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.1
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• pp.33-41
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• 2014

In a supersonic turbine, A rotor overlap technique reduced the chance of chocking in the rotor passage, and made the design pressure ratio satisfied. However, the technique also made additional losses, like a pumping loss, expansion loss, etc. Therefore, an approximate optimization technique was appled to find the optimal shape of overlap which maximizes the improvement of the turbine performance. The design variables were shape factors of a rotor overlap. An optimal design for rotor overlap reduces leakage mass flow rate at tip clearance by about 50% and increases about 4% of total-static efficiency compared with the base model. It was found that the most effective design variable is the tip overlap and that the hub overlap size is the lowest.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.8
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• pp.763-771
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• 2011

An optimization procedure for the design of a ventilation axial-flow fan is presented in this paper. Flow analyses of the preliminary fan are performed by solving three-dimensional Reynolds-averaged Navier-Stokes equations via a finite-volume solver with the shear-stress transport turbulence model as a turbulence closure. Three variables, the hub-to-tip ratio and the stagger angles at the mid and tip spans, are selected for the optimization. The Latin-hypercube sampling method as a design-of-experiments technique is used to generate twenty-five design points within the design space. and the weighted average surrogate models, WTA1, WTA2, and WTA3, are applied for find optimal designs. The results show that the efficiency is considerably enhanced.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.4
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• pp.25-31
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• 2013

A blisk with rotor shroud is usually adopted in LRE turbine to maximize its performance. However it experiences the severe thermal load and resulting damage during engine stating and stop. Shroud splitting is devised to relieve the thermal stress on the turbine rotor. Structural analysis confirmed the reduction of plastic strain at the blade hub and tip. However, split gap at the rotor shroud entails additional tip leakage and results performance degradation. In order to assess the effect of shroud split on the turbine performance, tests have been performed for various settings of shroud split. For the maximum number of shroud splitting, measured efficiency reduction ratio was 2.65% to the value of original shape rotor.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3050-3055
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• 2007

A wind turbine is one of the most popular energy conversion systems to generate electricity from the natural renewable energy source and an axial-flow type wind turbine is the most popular system for the electricity generation in the wind farm nowadays. In this study, a cross-flow type turbine has been studied for the application of wind turbine for electricity generation. The target capacity of electric power generation of the model wind turbine developing on the project is 12 volts, 130A/H (about 1.56kW). The important design parameters of the model turbine impeller are the inlet and exit angle of the turbine blade, number of blade, hub/tip ratio and the exit flow angle of the casing. In this study, the radial equilibrium theorem was used to decide the inlet and exit angle of the impller blade and CFD technique was used to have the performance analysis of the designed model power turbine to find out the optimum geometry of the CPT impeller and casing. The designed CPT with 24 impeller blades at ${\alpha}=82^{\circ}$, ${\beta}=40^{\circ}$ of turbine blade angle was estimated to generate 284.6 N.m of indicated torque and 2.14kW of indicated power.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.325-330
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• 2011

A rotor overlap technique was adapted to improve the performance of a axial turbine. The technique secured sufficient flow passage by additional height at the rotor tip and hub. especially in a supersonic turbine, the technique reduced the chance of chocking in the rotor passage, and made to be satisfied the design pressure ratio. However, the technique also made additional losses, like a pumping loss, expansion loss, etc. Therefore, a optimization technique was appled to maximize the improvement of the turbine performance. An approximate optimization method was used for the investigation to secure the computational efficiency. The design variables was shape factors of a rotor overlap. Results indicated that a significant improvement in turbine performance can be achieved through the optimization of the rotor overlap.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.275-278
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• 2006

A steam turbine is one of propulsion systems of a LNG carrier, which consists of high pressure (HP) and low pressure (LP) turbines. In order to obtain high power, each one has the form of a multi-stage turbine. Especially, the first stage of a HP turbine is Curtis stage and uses partial admission considering the turbine efficiency. The performance of a HP turbine can be predicted by a mean-line analysis method, because the relatively large value of hub-tip ratio makes the three-dimensional losses small. In this study, a performance analysis method is developed for a multi-stage HP turbine using Chen's loss model developed for the transonic steam turbines. To consider the feature of partial admission, different partial admission models are reviewed, This analysis method can be used in partial load conditions as well as full load condition. The calculation results are also compared with the CFD results about some simple cases to check the accuracy of the program. Performance of two HP turbine models are calculated, and the calculation results are compared with the designed data. The comparison shows the qualitative performance analysis result.

• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.58-63
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• 2012

This paper presents a numerical study on the performance improvement of axial-flow pump with guide vanes. Design optimization for guide vanes in an axial-flow pump has been studied through the implementation of a commercial CFD code and DOE (design of experiments). We also discussed how to improve the performance of the axial-flow pump by designing the guide vanes. Geometric design variables were defined by the meridional plane and vane plane development of guide vanes. The effect of hub tip ratio analyzed the meridional plane of guide vanes. The importance of the geometric design variables was analyzed using $2^k$ factorial designs. The objective functions for guide vane geometric variables were defined as the total efficiency and the total head at the design flow rate. From the $2^k$ factorial design results, the important design variables were found and the performance was increased in comparison with the base design model.