• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.99-108
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• 2004

In this paper, a small supersonic wind tunnel is designed and built to study the flow characteristics of a supersonic impulse turbine. The flow is visualized by means of a single pass Schlieren system. The supersonic cascade with 2-dimensional supersonic nozzle was tested over a wide range of pressure ratio. Highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions are observed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.100-105
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• 2005

In this paper, a small supersonic wind tunnel is designed and built to study the flow characteristics of a supersonic impulse turbine cascade. The flow is visualized by means of a single pass Schlieren system. The supersonic cascade with 2-dimensional supersonic nozzle is tested for various gaps between the nozzle and cascade. By the experiment, the flow is visualized and static pressure of the cascade was measured. And highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions, flow characteristics of the supersonic turbine are observed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.61-65
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• 2011

In this paper, the nozzle design with asymmetric configuration using the optimal method is used in order to improve the under- and over-expansion problem of the flow at the supersonic turbine nozzle. For the design of nozzle contour, 8 design variables are selected and the total-to-static efficiency from the nozzle inlet to the wake outlet is considered as the objective function to be maximized. The Fluent6.3 and the iSIGHT-FD program are used for calculation of nozzle flow and design optimization respectively. RBF(Radial Basis Function) method is chosen for approximate optimization algorithm. It is shown that the static efficiency of improved nozzle design increases 1.35% and loss coefficient decreases 19.85% as compared to baseline design.

• 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 Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.93-96
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• 2011

A genetic algorithm (GA) has been employed to optimize the major design variables of the liquid rocket engine. Mass flow rate to the main thrust chamber, mass flow rate to the gas generator and chamber pressure have been selected as design variables. The target engine is the open gas generator cycle using the LO2/RP-1 propellant. The objective function of design optimization is to maximize the specific impulse with condition of energy balance between the pump and the turbine. The properties of the combustion chamber have been obtained from CEA2. Pump & turbine efficiencies and properties of the gas generator have been modeled mathematically from reference data. The result shows 3~4% errors for the specific impulse and 2~6% errors for the pump power of the gas generator cycle compared to references.

• 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.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.2
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• pp.111-117
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• 2012

Oscillating water column is the most widely used ocean energy converting systems all over the world. The operating performance is influenced by the efficiencies of the two converting stages in the OWC chamber-turbine integrated system. In order to consider the effects of the turbine, the orifice model are carried out. The VOF based Numerical Wave Tank (NWT) is utilized to simulate the water column oscillation inside the chamber and the results are compared with corresponding experimental data. This paper reviews the state of the art in interaction among wave elevation inside the chamber and air flow rate in the duct, which are considered the turbine effects. Effects of incident wave conditions and several shape parameters on the operating performance of OWC chamber are investigated numerically. The effects of the impulse turbine on the integrated system and interaction among the wave elevation, pressure and air flow velocities variations are investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.375-383
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• 2005

The present paper describes the first development of a LOX/kerosene type turbopump in Korea. The liquid rocket engine, that the turbopump can be applied to, has a 30-ton(metric) level of vacuum thrust and employs a gas generator cycle. The turbopump consists of two single-stage centrifugal pumps, that is, LOX and kerosene pumps, and one single-stage impulse turbine. Inter-propellant seal(IPS) is located between the LOX pump and the kerosene pump to avoid any interaction between the propellants. A series of component and TPU(Turbopump Unit) test has been completed in the level of simulant propellants and ready for hot firing tests.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.9
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• pp.805-815
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• 2007

In order to build a conceptual design program for a liquid rocket engine system, performance based sub-programs for each core component of the engine system were made. Parts included were the combustion chamber, supersonic nozzle, centrifugal pump, and impulsive turbine. Simple mathematical models based on classical thermodynamic and inviscid theories were adopted with proper tuning by empirical data. In Part I, aiming to validate each sub-program, we examined the results of each program qualitatively, and parametrically investigated the sensitivity due to the change in design parameters.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.4
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• pp.66-72
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• 2005

In this paper, a small supersonic wind tunnel is designed and built to study the flow characteristics of a supersonic impulse turbine cascade. The flow is visualized by means of a single pass Schlieren system. The supersonic cascade with 2-dimensional supersonic nozzle was tested for various blade leading edge shapes and gaps between the nozzle and cascade. Highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions are observed.