• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.6
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• pp.21-29
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• 2008

Performance characteristics on a partially admitted small axial-type turbine are experimentally studied with changing design parameters, such as exit flow angles at the nozzle and solidities at the rotor. The tested turbine consists of a single-stage and its mean radius is 35 mm. In this experiment, three different solidities and four different nozzle flow angles are applied to find the optimal design parameter. For a comparison of the turbine performance, the net specific output powers are evaluated. For a 3.4% partial admission rate, the best performance is obtained when the rotor solidity is at 2.18, which is increased to 74% compared to the solidity at full admission.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.7
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• pp.831-840
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• 1999

In this work, an aerothermodynamic calculation model for cooled axial flow turbine blades with trailing edge ejection is suggested and a mean line performance analysis of a turbine stage with nozzle cooling is carried out. A unique model regarding the interaction between coolant and main gas is proposed, while existing correlations are adopted to predict viscous loss and blade outflow angle. The interactions considered are the heat transfer from main gas to coolant and the temperature and pressure losses by the mixing of two streams due to the trailing edge coolant ejection. For a stator blade without ejection, trailing edge loss calculated by the trailing edge analysis is compared with that calculated by loss correlation. The effect of heat transfer effectiveness of coolant passage on the mixing loss is analyzed. For a model turbine stage with nozzle cooling, parametric analyses are carried out to investigate the effect of main design variables(coolant mass flow ratio, temperature and ejection area) on the stage performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.9
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• pp.898-906
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• 2008

A tested turbine consists of two stages, and an axial-type and a radial-type turbine are applied to the first and second stage, respectively. The mean diameter of the axial-type turbine rotor is 70 mm, and the outer diameter of the radial-type turbine is 68mm at the inlet. In this experiment, an axial-type turbine, two different radial-type turbines, and three different nozzle flow angles are applied to find the optimal design parameters. To compare the turbine performance, the net specific output torque is evaluated. The test results show that the nozzle flow angle on the first stage is a more important parameter than other design parameters for partially admitted small turbines to obtain high operating torque. For a 3.4% partial admission rate, the net specific output torque is increased by 13% with the addition of a radial-type rotor to the second stage when the turbine operates at $75^{\circ}$ nozzle flow angle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.2
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• pp.141-148
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• 2009

Axial-flow compressor is one of the most important parts of gas turbine units with axial turbine and combustor. Therefore, precise prediction of performance is very important for development of new compressor or modification of existing one. Meanline analysis is a simple, fast and powerful method for performance prediction of axial-flow compressors with different geometries. So, Meanline analysis is frequently used in preliminary design stage and performance analysis for given geometry data. Much correlations for meanline analysis have been developed theoretically and experimentally for estimating various types of losses and flow deviation angle for long time. In present study, meanline analysis program was developed to estimate compressor losses, incidence angles, deviation angles, stall and surge conditions with many correlations. Performance prediction of one stage axial compressors is conducted with this meanline analysis program. The comparison between experimental and numerical results show a good agreement. This meanline analysis program can be used for various types of single stage axial-flow compressors with different geometries, as well as multistage axial-flow compressors.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.42-48
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• 2004

Numerical simulation of viscous compressible flow in turbomachinery cascade involves many problems due to the complex geometry of blade but also flow phenomena. In the present study, numerical investigations have been performed to examine the three-dimensional flow characteristics inside the transonic linear turbine cascades using a commercial code, FLUENT. Multi-block H-type grids are applied to the high-turning turbine rotor blades and comparisons with the experimental data and the numerical results have been done. In addition, the effects of turbulence models on the prediction of the endwall flows are analyzed in the sense of the flow compressibility.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.8
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• pp.1173-1182
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• 1998

A throughflow analysis program for axial flow turbines is constructed, which can handle not only the two-dimensional multi-streamline (streamline curvature) method but also the one-dimensional mean line method. Calculations are performed for single stage and multi-stage axial flowturbines. For a wide operating range, the performance and flow field calculated by the present streamline curvature method are close enough to the test data. It is also revealed for the single stage turbine that the present analysis leads to far better correspondence with the experiment than other researchers" throughflow analyses. A special focus is put on the comparison of the results between the streamline curvature analysis and the mean line analysis. It is found that the mean line analysis can not predict the performance for highly off-designed conditions as accurately as the streamline curvature method, which shows the importance of considering the spanwise variation of loss and flow.

• Journal of computational fluids engineering
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• v.8 no.4
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• pp.16-25
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• 2003

The design method for transonic turbine blades has been developed based on Wavier-Stokes equations. The present computing process is done on the four separate steps, i.e., determination of the blade profile, generation of the computational grids, cascade flow simulation and analysis of the computed results in the sense of the aerodynamic performance. The blade shapes are designed using the cubic polynomials under the control of the design parameters. Numerical methods for the flow equations are based on Van-Leer's FVS with an upwind TVD scheme on the finite volume. In the present study, numerical simulation has been done to investigate the effects of the design parameters on the aerodynamic peformance of the axial-flow turbine blades. Applications are made to the VKI transonic rotor blades. Computed results are analyzed with respect to four parameters and compared with the experimental data.

• International Journal of Fluid Machinery and Systems
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• v.9 no.1
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• pp.47-55
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• 2016

The portable hydraulic turbine we previously developed for open channels comprises an axial flow runner with an appended collection device and a diffuser section. The output power of this hydraulic turbine was improved by catching and accelerating an open-channel water flow using the kinetic energy of the water. This study aimed to further improve the performance of the hydraulic turbine. Using numerical analysis, we examined the performances and flow fields of a single runner and a composite body consisting of the runner and collection device by varying the airfoil and number of blades. Consequently, the maximum values of input power coefficient of the Runner D composite body with two blades (which adopts the MEL031 airfoil and alters the blade angle) are equivalent to those of the composite body with two blades (MEL021 airfoil). We found that the Runner D composite body has the highest turbine efficiency and thus the largest power coefficient. Furthermore, the performance of the Runner D composite body calculated from the numerical analysis was verified experimentally in an open-channel water flow test.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.1
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• pp.182-190
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• 2001

The aerodynamics of the Wells turbine has been studied using 3-d, unstructured mesh flow solver for the Reynolds-averaged Navier-Stokes equations. The basic feature of the Wells turbine is that even though the cyclic airflow produces oscillating axial forces on the airfoil blades, the tangential force on the rotor is always in the same direction. Geometry used to define 3-D numerical grid is based upon that of an experimental test rig. The 3-D Wells turbine model, consisting of approximate 220,000 cells is tested of four axial flow rates. In the calculations the angle of attack has been varied between 10˚ and 30˚ of blades, Representative results from each case are presented graphically andy analysed. It is concluded that this technique holds much promise for future development of Wells turbines.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.7 s.94
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• pp.1851-1863
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• 1993

A procedure for the prediction of the off-design performance of a gas turbine engine is proposed. The system performance at off-design speed is predicted by coupling the thermodynamic models of a compressor and a turbine. The off-design performance of a compressor is obtained using the stage-stackimg method, while the Ainlay-Mathieson method is used for a turbine. The procedure is applied to a single-shaft gas turbine and its predictability is found satisfactory. The results also show that the net work output increases with the increase of the turbine inlet temperature, while the thermal efficiency is marginal. The maximum thermal efficiency at design point is obtained between the highest pressure ratio and design pressure ratio.