• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.1-12
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• 2018

The streamline curvature method is essentially used for the design procedure of multi-stage axial turbines. Moreover, by using this method, it is possible to consider the turbine loss characteristics for real operating conditions at an early design stage. However, there is not enough relevant research in South Korea to support this. In the present study, the streamline curvature method and the empirical equation for calculating the mixing loss are employed to predict the performance of a multi-stage axial turbine with leakage flows. The proposed method is applied to the prediction of the performance of a five-stage axial turbine with leakage flows, as used for an industrial gas turbine of 86 MW in South Korea. The calculation result is compared with 3D CFD data, and the advantages and limitations of the streamline curvature method are described.

• 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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.70-77
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• 1986

Turbulent mixing field with recirculating flow which is formed by injecting gaseous fuel on the main air stream is solved numerically by a finite difference method. The turbulence model for obtaining transport properties was k-.epsilon. model, which was obtained from turbulent kinetic energy and its dissipation rate. Considering the effects of streamline curvature, modified k-.epsilon model was used. Generally, Modified k-.epsilon. model makes better predictions than standard model, and from this result, it is recognized that standard model has deficiency when applied to turbulent recirculating flows, and that modified k-.epsilon. model takes into account of streamline curvature effects properly. Meanwhile, A more study will be necessary to find the reason why large differences between predicted and experimental turbulent kinetic energy exist.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.1
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• pp.87-96
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• 1989

Flows through impellers of centrifugal compressors are calculated by a streamline curvature method. A method for the exit boundary condition is suggested in the present paper. Flow angles are assumed to be deviated from the blade angle parabolically. The maximum deviation is adjusted for the whole angular momentum to balance with the empirically estimated value by using Stanitz' slip-factor. The present method is verified to reasonably simulate flows through the impeller, when the 3-dimensionality of the flow is not strong. It is also shown that the method can be applied for the design of the splitter in the impeller.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2001.04a
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• pp.59-62
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• 2001

An axial-type turbine design technology is developed. In order to design one-stage turbine, preliminary design method is applied, and then design parameters are chosen after analyzing the 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. The output power is measured with various RPM and input power. The experimental result shows that the output power is proportionally decreased with the negative incidence angle.

• 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.

• The KSFM Journal of Fluid Machinery
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• v.7 no.2 s.23
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• pp.7-13
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• 2004

In an attempt to solve multiobjective optimization problems, weighted sum method is most widely used for the advantage that a designer can consider the relative significance of each object functions by weight values but it can be highly sensitive to weight vector and occasionally yield a deviated optimum from the relative weighting values designer designated because the multiobjective function has the form of simple sum of the product of the weighting values and the object functions in traditional approach. To search the design solution agree well to the designer's weighting values, we proposed new multiobjective function which was the functional of each normalized objective functions and considered to find the design solution comparing the distance between the characteristic line and the ideal optimum. In this study, proposed multiobjective function was applied to design high efficiency and low noise axial flow fan and the result shows this approach is effective for the case that the quality of the design can be highly affected by the designer's subjectiveness represented as weighting values in multiobjective design optimization process.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1591-1602
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• 1998

Simple spanwise distribution models of deviation angle and pressure loss coefficient due to the tip leakage flow are formulated for use in association with the streamline curvature method as a flow analysis. Combining these new models with the previous deviation and loss models due to secondary flow, a robust streamline curvature method is established for flow analysis of single-stage, subsonic axial turbines with wide ranges of turning angle, aspect ratio and blading type. At the exit from rotor rows, the flow variables are mixed radially according to a spanwise transport equation. The proposed streamline curvature method is tested against a forced vortex type turbine as well as a free vortex type one. The results show that the spanwise variations of flow angle, axial velocity and loss coefficients at rotor exit are predicted with good accuracy, being comparable to a steady three-dimensional Navier-Stokes analysis. This simple and fast flow analysis is found to be very useful for the turbine design at the initial design phase.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.397-403
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• 2003

In an attempt to solve multiobjective optimization problems, weighted sum method is most widely used for the advantage that a designer can consider the relative significance of each object functions by weight values but it can be highly sensitive to weight vector and occasionally yield a deviated optimum from the relative weighting values designer designated because the multiobjective function has the form of simple sum of the product of the weighting values and the object functions in traditional approach. To search the design solution well agree to the designer's weighting values, we proposed new multiobjective function which is the functional of each normalized objective functions and considered to find the design solution comparing the distance between the characteristic line and the ideal optimum. In this study, proposed multiobjective function was applied to design high efficiency and low noise axial flow fan and the result shows this approach will be effective for the case that the qualify of the design can be highly affected by the designer's subjectiveness represented as weighting values in multiobjective design optimization process.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1158-1174
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• 1988

A numerical technique is developed for the solution of fully developed turbulent recirculating flow in the passage of variable area using the non-orthogonal coordinate transformation. In the numerical analysis, primitive pressure-velocity finite difference equations were solved by SIMPLER algorithm with 2-equation turbulence model and algebraic stress model (ASM). QUICK scheme on the differencing of convective terms which is free from the inaccuracies of numerical diffusion has been applied to the variable grids and the results compared with those from HYBRID scheme. In order to test the effect of streamline curvatures on turbulent diffusion Lee and Choi streamline curvature correction model which has been obtained by modifying the Leschziner and Rodi's model is testes. The ASM was also employed and the results are compared to those from another turbulence model. The results show that difference of convective differencing schemes and turbulence models give significant differences in the prediction of velocity fields in the expansion region and outlet region of the combustor, however show little differences in the parallel flow region.