• Journal of Aerospace System Engineering
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• v.11 no.1
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• pp.8-13
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• 2017

This study was performed to evaluate the turbine performance of a turbopump in the third stage engine of the Korea Space Launch Vehicle-II. The turbine is a supersonic impulse type with a single rotor. One nozzle is for starting and four remaining nozzles are for steady operation. A similarity test was carried out in the high air test facilities at the Korea Aerospace Research Institute. Test results showed that turbine efficiency changed much more from rotational speed variations than by pressure ratio variations. These results showed characteristics similar to other supersonic impulse turbines.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.149-152
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• 2010

It was investigated that effect of the supersonic impulse turbine rotor leading edge thickness which was the part of 75 ton open cycle liquid rocket engine turbopump. The test for turbine was performed that the rotor thickness to pitch ratio was 1.9 and 1.4 to 30 ton turbine. As a result of test, the rotor with lower thickness(1.4) had 1.5% efficiency gain to the higher thickness(1.9) and the pressure ratio with maximum efficiency was increased to the nozzle full expansion point.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.387-392
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• 2006

A small supersonic wind tunnel was designed and built to study the flow characteristics of a supersonic impulse turbine cascade. Experiments are performed to find flow characteristics of supersonic turbine with the cascade positions and to find factor of expansion loss. The supersonic cascade with a 2-dimensional supersonic nozzle was tested with the cascade positions. Firstly, the flow was visualized by Z-type Schlieren system. Finally, highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions, flow characteristics of the supersonic turbine were observed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.297-301
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• 2007

The blades of supersonic turbines with low aspect ratio are usually designed to have the same cross sectional shape in radial direction. The profile diameter definition of turbines may lead to produce unintended flow passage area variations resulting performance degradation. In this paper, the effects of profile diameter definition on the supersonic impulse turbine performance have been investigated. Computational results of three different profile diameters are compared. It has been found that flow passage area variation can be achieved according to designer's intention when blade profile is defined at rotor tip diameter. Furthermore, the turbine blade profile defined at rotor tip showed better performance than the others.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.361-366
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• 2006

A small supersonic wind tunnel was designed and built to study the flow characteristics of a supersonic impulse turbine cascade. The supersonic cascade with a 2-dimensional supersonic nozzle was tested for the leading edge chamfer angle $(\gamma)$ of the supersonic turbine that is the one of the turbine design parameter. Firstly, the flow was visualized by a single pass Schlieren system. Next, total and static pressure of the cascade were measured by a pressure scanning system. Finally, highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions, flow characteristics of the supersonic turbine were observed.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.1
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• pp.19-28
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• 2011

As a preview study, present research analysed the performance characteristics of a velocity compound supersonic impulse turbine with the rotor overlaps before adapting the overlap has the best turbine performance. This research was conducted for the turbine with square cross-section nozzles instead of axisymmetric nozzles and wrap around nozzles. Through 3-dimensional flow analysis for the turbine by a commercial flow analysis package, tip overlap case was more effective to improve the turbine performance than case hub overlap, and overlap case applied the hub and tip of the rotor had the largest improvement for the turbine performance in the cases. In case of overlap for the 2nd stage rotor, improvement of the turbine performance was not visibly large. Because, generated power in the 2nd stage is 22~23% of whole generated turbine power.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.136-142
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• 2007

A small supersonic wind tunnel was designed and built to study the flow characteristics of a supersonic impulse turbine cascade. The supersonic cascade with a 2-dimensional supersonic nozzle was tested for the axial gap ratio (${\delta}$) of the supersonic turbine that is the one of the turbine design parameter. Firstly, the flow was visualized by a single pass Schlieren system. Next, total and static pressure of the cascade were measured by a pressure scanning system. Highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions, flow characteristics of the supersonic turbine were observed.

• International Journal of Aeronautical and Space Sciences
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• v.16 no.4
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• pp.571-580
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• 2015

In this paper, a computational study was conducted in order to investigate the rotor blade sweep effect on the aerodynamics of a small axial supersonic impulse turbine stage. For this purpose, three-dimensional unsteady RANS simulations have been performed with three different rotor blade sweep angles ($-15^{\circ}$, $0^{\circ}$, $+15^{\circ}$) and the results were compared with each other. Both NTG (No tip gap) and WTG (With tip gap) models were applied to examine the effect on tip leakage flow. As a result of the simulation, the positive sweep model ($+15^{\circ}$) showed better performance in relative flow angle, Mach number distribution, entropy rise, and tip leakage mass flow rate compared with no sweep model. With the blade static pressure distribution result, the positive sweep model showed that hub and tip loading was increased and midspan loading was reduced compared with no sweep model while the negative sweep model ($-15^{\circ}$) showed the opposite result. The positive sweep model also showed a good aerodynamic performance around the hub region compared with other models. Overall, the positive sweep angle enhanced the turbine efficiency.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.382-386
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• 2006

Three dimensional numerical analysis of the supersonic turbines with different rotor tip clearances was conducted to analyze the effect of the tip gap clearance variations on the turbine performance. The result showed that the turbine performance deteriorates and the tip leakage increases by the effect of the rotor tip clearance and the tip leakage affects turbine performance degradation dominantly.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.561-565
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• 2009

The performance of supersonic impulse turbine was investigated experimentally. Experiment was performed with the compressed air instead of the high temperature burned gas because of the limitation of test facility and danger. As a result of the experiment with the compressed air, the performance in the real gas(burned gas) was predicted by the similarity method. The nozzle area of prototype turbine was calculated based on the real gas. So, it is difficult to satisfy the similarity conditions completely. Two similarity conditions were set and the design point for real gas was existed between two similarity conditions. And, the new turbine test model with calculated nozzle area based on the compressed air was tested. Therefore, similarity point of the new turbine test model was also existed between above two similarity points. It means that the design point for real gas was similar to the test point with the new turbine model.