• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.3
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• pp.411-418
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• 2000

By calculating the location and size of the relative eddy formed in the rotating impellers with the logarithmic spiral vanes, a new simple but accurate slip factor is analytically derived. The proposed slip factor depends on only one parameter that is a function of the number of vanes and the vane exit angle. Predicted slip factor for various cases are compared with those estimated by a number of previous slip factors as well as a recent theoretical calculation by Visser et al. ( JFM, Vol. 268, pp. 107-141, 1994). It is found that the present slip factor yields almost similar results to Wiesner's which has been empirically formulated based on the theoretical calculation of Busemann.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.5
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• pp.9-18
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• 2016

Generally the variable guide vane is used to secure the sufficient operating point in the off-design condition. In this study the inlet guide vane, 1st and 2nd stators in a multi-stage axial compressor are movable to obtain the operating range. So the effects of variable guide vane setting angle on the performance of 2.5 stage axial compressor were investigated at 70 % and 90 % conditions of nominal rotating speed in this paper. The steady-state and unsteady numerical analyses were conducted at each operating condition. The performance map, lost efficiency and flow fields were compared.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.1
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• pp.53-60
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• 2005

The use of pipe-bends brings about non-uniform flows at the exit of them due to the velocity difference between inner and outer flows inside the bend. These phenomena may cause turbopump of satellite launch vehicle to run off-design and reduce its efficiency, and also introduce unstable influx of propellants to engine manifold after passing through a turbopump. In order to improve the uniformity of flow at the bend exit, certain turning vanes are set up in the bend pipe normally. Correspondingly the design is an $90^{\circ}\;and\;45^{\circ}$ bend pipes that incorporate with the maximum three turning vanes. All designs were analyzed with numerical analysis by solving the Navier-Stokes equations in three dimensions in case of each respective fuel and oxidizer. Evaluations of the vaned pipe bends designs were accomplished by the velocity magnitude distributions and the predicted pressure drops. We could find that the more vaned bend pipe and larger angle pipe under consideration effectively, the more uniform velocity magnitude of the bend and pressure losses.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.2
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• pp.34-41
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• 2012

Thrust vector control system is a control device which is mounted on the exit of the nozzle to generate pitch, yaw and roll directional force by deflecting flow direction of the supersonic jet from the nozzle. Thermal and aerodynamic loads are acting on the surface of jet vane when it is exposed to the jet flow. Axial thrust loss and side thrust loss are affected by shock patterns and interactions between jet-vanes which varies with jet-vane geometry and turning angle. In this research, the performance estimation using the numerical simulation analysis of the nozzle is given and the investigation of the flow visualization and aerodynamic performance with the enforced power to the vane is taken.

• Journal of Hydrogen and New Energy
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• v.31 no.4
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• pp.395-403
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• 2020

In this paper, the performance characteristics of the impeller and volute in the 2 vane pump were investigated using response surface method (RSM) with commercial computation fluid dynamics (CFD) code. Design variables were defined with the impeller blade angle and volute area distribution. The objective functions were defined as the total head, total efficiency and solid material size of the 2 vane pump. The design optimization of the design variables was determined using the RSM. The numerical results for the reference and optimum models were compared and discussed in this work.

• The KSFM Journal of Fluid Machinery
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• v.14 no.1
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• pp.66-76
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• 2011

The heat transfer and pressure loss characteristics of a rotating two-pass channel with a guide vane in the turning region have been studied using three-dimensional Reynolds-averaged Navier-Stokes (RANS) analysis, and the shape of the guide vane has been optimized using surrogate modeling optimization technique. For the optimization, thickness, location and angle of the guide vanes have been selected as design variables. The objective function has been defined as a linear combination of the heat transfer and the friction loss related terms with a weighting factor. Latin hypercube sampling has been applied to determine the design points as design of experiments. A weighted-average surrogate model, PBA has been used as the surrogate model. The guide vane in the turning region does not influence the heat transfer in the first passage upstream of the turning region, but enhances largely the heat transfer in the turning region and the second passage. In an example of the optimization, the objective function has been increased by 13.6%.

• The KSFM Journal of Fluid Machinery
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• v.11 no.5
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• pp.44-49
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• 2008

As the alternative energy, renewable energy should have been developing by many techniques, in order to substitute the fossil fuel which will be disappeared in the near future. One of the small hydropower generator, main concept of tubular turbine is based on using the different water pressure levels in pipe lines, energy which was initially wasted by using a reducing valve at the end of the pipeline, is collected by turbine in the hydro power generator. A propeller shaped hydro turbine has been used in order to use this renewable pressure energy in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the guide vane opening angle are examined in detail. First, it ensures the reliance of CFD by that of compared with experiment data. After all, the results of performance characteristics of the CFD and experiment show to confirm the data that power, head and efficiency of less than 4%, 2% and 5% respectively. Moreover influences of pressure, tangential and axial velocity distributions on turbine performance are investigated.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2839-2844
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• 2007

Micro hydraulic power generation of which the output is less or equal to a 100kW is attracting considerable attention. This is because of its small, simple, renewable, and abundant energy resources. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Moreover influences of pressure and velocity distributions with the variations of runner vane angle on turbine performance are investigated by using a commercial CFD code.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.7
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• pp.1044-1050
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• 2008

Most of developed countries, the consumption of fossil fuels has been serious problems that cause serious environment pollution like acid rain, global warming. Also, we have faced that limitation fossil fuels will be exhausted. Currently, small hydropower attracts attention because of its small, clean, renewable, and abundant energy resources to develop. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Tubular-turbine among small hydraulic power generation can be used at low-head. The purpose of this study is to research turbine's efficiency due to runner vane angle using CFD analysis.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.4
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• pp.347-354
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• 2001

SCR (Selective Catalytic Reduction) process is presently considered as one of the most effective techniques for removing nitric oxides from exhaust gases. In this study, based on the conceptually designed SCR reactor of 500 MW coal fired power plant. a reduced scale (1/20) SCR reactor model was made to analyze the flow pattern in front of catalyst layer according to the guide vane's design factors such as the number, interval, and angle of vanes. The results of the test were compared to those numerical simulation in order to assure the reliability of two methods. On the basis of our study. the critical Reynolds number (2.0$\times$ 10$^{5}$ ) was proposed for ensuring the similarity between the reduced scale model and the prototype of SCR reactor. Optimum design parameters of guide vanes were determined as follows, 4 vanes, the first vane angle of 93$^{\circ}$, and the vane intervals of 0.85 S/n, 1.05 S/n, 1.1 S/n, 1.0S/n, 1.0S/n (S: the distance of duct, n: the number of guide vanes). The excellent agreement between the results of the numerical simulation and the reduced scale model provides the validation of two methods for prediction of flow through SCR reactor.