• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.191-196
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• 2005

For the improvement of aerodynamic performance of the turbine blade in a turbopump for the liquid rocket engine, the optimization of turbine profile shape has been studied. The turbine in a turbopump in this study is a partial admission of impulse type, which has twelve nozzles and supersonic inflow. Due to the separated nozzles and supersonic expansion, the flow field becomes complicates and shows oblique shocks and flow separation. To increase the blade power, redesign of the blade shape using CFD and optimization method was attempted. The turbine cascade shape was represented by four design parameters. For optimization, genetic algorithm based upon non-gradient search has been selected as a optimizer. As a result, the final blade has about 4 percent more blade power than the initial shape.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.119-124
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• 2004

In this study, a rotor blade of a Curtis turbine is investigated. Bezier curve is generally used to define the profile of turbine blades. However, this curve gives a feature of global control, which is not proper to a supersonic impulse turbine blade. Thus, a blade design method is developed by using B-spline curve so that local control is possible to obtain an optimized blade section. To design a Curtis turbine blade section systematically, the blade section has been changed by varying three design parameters using central composite design method. Flow analyses have been carried out for the blade sections, and the effects of design parameters are evaluated.

• Journal of computational fluids engineering
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• v.8 no.3
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• pp.1-6
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• 2003

Three-dimensional endwall flow within a linear cascade passage of high performance turbine blade is simulated with a 3-D Wavier-Stokes CFD code (MOSA3D), which is based on body-fitted coordinate system, pressure-correction and finite volume method. the endwall flow characteristics, including the development and generation of horseshoe vortex, passage vortex, etc. are clearly simulated, consistent with the generally known tendency The effects of both turbulence model and convective differencing scheme on the Prediction performance of endwall flow are systematically analyzed in the present paper. The convective scheme is found to have stronger effect than the turbulence modei on the prediction performance of endwall flow. The present simulation result also indicates that the suction leg of the horseshoe vortex continues on the suction side until it reaches the trailing edge.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.143-148
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• 2007

An impulse turbine, which is a main component of a liquid rocket engine, needs to be a small size with light weight and generate large power. Since the impulse turbine is being operated under complicated supersonic conditions, flow analysis and performance prediction largely depend on CFD technique. In order to increase the reliability of the prediction code, however, it often requires an experimental data to compare. In this research a rotating turbine rotor with multiple blades is simulated with a two-dimensional stationary cascade to check the effect of major flow parameters. Mach number is measured at nozzle exit by using a pitot tube and the blade thrust was also measured with a load cell. The measured thrust coefficient and the power are compared well with the designed conditions, which proves the design procedures are properly taken.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1311-1319
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• 1990

For the purpose of preventing the flow undulation in the cascade of steam turbine, the blades are made into a constant expansion rate in static pressure. And the flow in those cascades is transonic or supersonic in the range of 0.7-2.0 in Mach number. As a consequence, an oblique shock wave, known as inner or outer edge shock wave, arises in the flow of cascades. Especially when the steam in cascades is in a state of high wetness, nonequilibrium condensation and condensation shock wave occur, and they give rise to an interference with oblique shock wave. In the present study the case of expansion of moist air through a supersonic nozzle of constant expansion rate, which behaves similar to that of wet steam, was adopted. The effect of nonequilibrium condensation on the oblique shock wave generated by placing the wedge into the supersonic part of the nozzle was investigated. Furthermore, the relationship between nonequilibrium condensation zone and incident point of the oblique shock wave, oblique shock wave angle, the variations of angles of incident and reflected shock waves due to the variation of initial stagnation supersaturation and the relationship between the height of Mach stem and initial stagnation supersaturation are discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.2
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• pp.316-328
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• 1997

There were appreciable progresses on the study of shock wave / boundary layer interaction control in the transonic flow without nonequilibrium condensation. But in general, the actual flows associated with those of the airfoil of high speed flight body, the cascade of steam turbine and so on accompany the nonequilibrium condensation, and under a certain circumstance condensation shock wave occurs. Condensation shock wave / boundary layer interaction control is quite different from that of case without condensation, because the droplets generated by the result of nonequilibrium condensation may clog the holes of the porous wall for passive control and the flow interaction mechanism between the droplets and the porous system is concerned in the flow with nonequilibrium condensation. In these connections, it is necessary to study the condensation shock wave / boundary layer interaction control by passive cavity in the flow accompanying nonequilibrium condensation with condensation shock wave. In the present study, experiments were made on a roof mounted half circular arc in an indraft type supersonic wind tunnel to evaluate the effects of the porosity, the porous wall area and the depth of cavity on the pressure distribution around condensation shock wave. It was found that the porosity of 12% which was larger than the case of without nonequilibrium condensation produced the largest reduction of pressure fluctuations in the vicinity of condensation shock wave. The results also showed that wider porous area, deeper cavity for the same porosity of 12% are more favourable "passive" effect than the cases of its opposite. opposite.